HK1063709B

HK1063709B - High-frequency heating device

Info

Publication number: HK1063709B
Application number: HK04106403.4A
Authority: HK
Inventors: 吉野浩二; 柏本隆; 涩谷诚; 今井博久; 阿波根明
Original assignee: 松下电器产业株式会社
Priority date: 1994-10-20
Filing date: 1998-02-18
Publication date: 2007-08-10

Description

High-frequency electric wave heating device

This application is a divisional application entitled "high-frequency electric wave heating apparatus" having an application date of 19/10/1995 and an application number of 95195792.9.

Technical Field

The present invention relates to a high-frequency electric wave heating apparatus for heating an object to be heated such as food.

Background

A typical microwave oven as a high-frequency electric wave heating apparatus has conventionally been constructed as shown in fig. 1 to 7.

The microwave oven of fig. 1 is a general structure using a turntable 1. Here, the electromagnetic wave emitted from the magnetron 2 as the electromagnetic wave emitting means is transmitted through the waveguide 3, and becomes a standing wave distribution in the heating chamber 4 determined by the shape of the heating chamber 4 and the position of the opening 5 through which the electromagnetic wave is emitted into the heating chamber 4, and the food 6 generates heat due to the electric field component of the standing wave and the dielectric loss of the food 6. Power absorbed per unit of food P (W/m)³) The intensity E (V/m) and frequency f (Hz) of the applied electric field, and the specific dielectric constant ε r and the dielectric tangent tan δ of food 6 are expressed by formula (1). The heating distribution of the food 6 is substantially defined by the standing wave distribution of the electromagnetic waveIt is determined that the turntable 1 is driven to rotate to make the heating distribution uniform on the concentric circle in order to suppress the unevenness of the heating distribution.

P＝(5/9)ε_r tanδf E²×10^-10〔W/m³〕……(1)

In fig. 1, 19 is a control means, 22 is a motor, 23 is a weight sensor, and 27 is an electric fan.

As other homogenizing means, there are a stirrer system in which electromagnetic waves are stirred by a metal plate rotating at a constant speed in a heating chamber, and a method in which electromagnetic waves are led out from a waveguide 3 and a rotary waveguide (radiation section) 8 having a coupling section 7 and radiated from a radiation port 9, as shown in fig. 2, in other words, a method in which the opening itself is rotated at a constant speed. In this case, the rotary waveguide is provided on the bottom surface of the heating chamber 4, and is rotated at a constant speed by the motor 10, and the entire bottom surface portion of the heating chamber 4 is covered with the cover 11 made of a material capable of passing electromagnetic waves. But the most used commercial products are the turret type products.

Further, the electromagnetic wave generator may be provided with a plurality of openings, and the electromagnetic wave outlet may be switched to achieve uniformity. Fig. 3 shows a type in which two openings 5 are provided in a wall surface of the heating chamber 4 (japanese patent laid-open No. 4-319287).

In addition, there is a magnetron including a plurality of magnetrons and a plurality of waveguides for forming a plurality of openings

High-frequency electric wave heating apparatus (Japanese patent laid-open publication Nos. 61-181093 and 4-345788)

In addition, there is a high-frequency wave heating apparatus including one magnetron for forming a plurality of openings, and having a plurality of waveguides branching from one waveguide in a plurality of directions (Japanese patent laid-open publication No. Sho 61-240029 and Japanese patent laid-open publication No. Hei 1-129793.)

As shown in fig. 4, the end faces 14 of the two sub-ducts 13 are moved at positions facing the plurality of openings 5, and the openings 5 whose electromagnetic waves are apparently easy to go out are switched to achieve a uniform model (japanese patent laid-open No. s 5-74566).

As shown in FIG. 5, the metal part 12 is moved in a single waveguide 3 having a plurality of openings 5 to switch the openings 5 from which electromagnetic waves are easy to escape in the surface view, thereby achieving a uniform model (Japanese patent laid-open Nos. Hei 3-11588 and Hei 5-121160).

As shown in fig. 6 and 7, there is a heating chamber having a plurality of openings 5 in the upper and lower portions thereof, and the number of the openings 5 is changed between the lower portions thereof to make the heating chamber uniform (japanese patent laid-open No. 1-129793).

Further, a model in which the weight, shape, temperature, dielectric constant, and temperature and humidity electric field in the heating chamber of the food 6 are detected by various sensors and feedback control is performed is also put into practical use.

However, in the above-described conventional structure, when the heating chamber is connected to the waveguide and the electromagnetic wave is introduced into the heating chamber, the proper position of the opening portion for making the heating distribution uniform varies depending on the material and shape of the food, and there is a problem that all the food cannot be uniformly heated by one opening portion.

For example, it is generally known that if flat food is heated in an existing microwave oven, there is a significant uneven heating that begins at the edges and remains low in the center.

Further, the position of the opening causes a problem that when the opening is provided near the center of the bottom surface of the heating chamber, the bottom surface of the food is heated, and even heating is possible if the food is a liquid food capable of convection, and the temperature of the bottom surface rises due to light in the case of a solid food incapable of convection. In this case, the heating distribution on the concentric circles can be made uniform by using the turntable, but the radial distribution and the vertical distribution are not improved when viewed from the rotation center regardless of the rotation.

On the other hand, in a device for stirring electromagnetic waves such as a stirrer or a rotary waveguide, since the electric field distribution is changed in accordance with a method of rotating the switching opening, there is an effect of preventing electromagnetic wave concentration to some extent when it is desired to prevent electromagnetic wave concentration as much as possible in thawing treatment or the like. However, since the heating with the same electric field distribution is repeated for every revolution regardless of the food product to be stirred with a certain rotation, complete homogenization is impossible.

Even if there are a plurality of openings, a certain electric field is generated by simply opening the openings at the same time, and it is difficult to uniformize the heating distribution of all the foods, and as a result, there is no great difference in the heating distribution between the microwave oven of fig. 1 and the microwave oven of fig. 3. As a result, a finished state satisfactory to the user cannot be obtained unless the opening portion is diligently replaced to suit various foods.

The apparatus has a plurality of magnetrons and a plurality of waveguides, and switches the waveguides for conducting electromagnetic waves by controlling the oscillation of each magnetron. Therefore, although switching the opening through which the electromagnetic wave exits is effective for uniformizing the heating distribution, the increase in the number of magnetrons raises the price, and the increase in weight makes the transportation inconvenient.

There is also a device in which one waveguide is branched into a plurality of waveguides in a plurality of directions by using one magnetron, but there is a problem that an opening portion through which an electromagnetic wave is easy to go out cannot be completely switched, and an opening portion through which an electromagnetic wave is not intended to go out has a problem that an electromagnetic wave is allowed to go out to some extent. Moreover, the waveguide tube needs a large amount of sheet metal working materials, so that the cost is high, the manufacture is difficult, and the like.

Therefore, as shown in fig. 4, there is a method of moving the end face 14 of the sub-duct 13 at a position facing the plurality of openings 5 to switch the apparent electromagnetic wave to be easily emitted to the openings 5, which has some effect on the uniformization of the heating distribution. However, in consideration of the actual structure, a space occupied by a plurality of sub waveguides 13 and a space of a multiple sealing structure for preventing electromagnetic wave leakage when the end face 14 of the sub waveguide 13 is moved are required. Therefore, the whole microwave oven becomes larger or the effective volume inside the heating chamber becomes smaller than the size of the whole microwave oven. For the user, the larger the whole size, the more difficult the place is to place, and the smaller the effective volume, the less the food can be placed, all the more unsatisfactory. In addition, the microwave oven also has the problems of heavy weight and difficult transportation. Further, the end surface 14 of the sub-duct 13 including the seal structure is moved at a plurality of places, and a considerable amount of electric power may be consumed.

As shown in fig. 5, even if the metal portion is moved in the single waveguide 3 having the plurality of openings 5, there is a problem that the openings 5 through which the electromagnetic wave is easily emitted cannot be completely switched, and the electromagnetic wave is emitted to some extent through the openings 5 through which the electromagnetic wave is not intended to be emitted.

In the configurations of fig. 1, 3, 4, and 5, the opening 5 is present only on the side surface, and the distance from the opening 5 to the food 6 is long.

When the distance from opening 5 to food 6 is long, not only the electromagnetic wave entering food 6 through opening 5 but also the electromagnetic wave emitted from the opening, reflected by the wall surface of heating chamber 4, and entering food 6 increases in proportion. Therefore, in this case, there is a problem that the heating distribution of the food 6 is greatly different depending on the size of the heating chamber 4, the placement position of the food 6, and the shape of the food 6.

For the same reason, there is a problem that the food 6 is always easily heated in the periphery.

In addition, with the configurations of fig. 6 and 7, a more uniform heating distribution than that obtained with the conventional configuration can be obtained. However, since the electromagnetic wave normally comes out from the upper portion, the periphery of the food is easily heated, and there is a problem that the portion between one opening of the lower portion and the adjacent opening of the lower portion cannot be heated.

Here, in the conventional configurations of fig. 1, 3, 4, 5, 6, and 7, it can be said that only the portion having the opening can concentrate electromagnetic waves, and uneven heating may occur.

In the structures of fig. 3, 5 to 7, the distance from the magnetron 2 to the opening 5 is not described.

In general, whether or not the electromagnetic wave easily enters the heating chamber 4 varies depending on the adaptation depending on where the opening 5 is provided in the heating chamber 4, the length of the waveguide, the distance from the magnetron 2 to the opening 5, and the like. In particular, the ease with which the electromagnetic wave can exit the waveguide 3 varies periodically in g/2, where g is the wavelength of the electromagnetic wave in the waveguide. Therefore, in the case of having a plurality of openings, in order to make the electromagnetic wave exit from each opening 5 similarly convenient, there is a problem that the entire adjustment must be performed in accordance with each opening 5.

If the position of the opening is determined only for the purpose of increasing the distribution and the adjustment of the fitting is not performed, the electromagnetic wave is less likely to enter the heating chamber, and the heating efficiency is lowered. Further, there is a problem that prevention measures are taken because electromagnetic waves reflected to the magnetron 2 increase, temperature rises, or noise is generated.

In order to detect the state of food by a sensor and perform feedback adjustment, a sensor for detecting the state of food at the initial stage of heating, the state of change from the initial stage of heating, or the end point of heating, such as a weight sensor, a humidity sensor, a temperature sensor, an electromagnetic field detection sensor, a steam detection sensor, or an alcohol detection sensor, is required. However, none of these sensors has been put into practical use in detecting the heating distribution or performing feedback control to correct uneven heating.

Disclosure of Invention

In order to achieve the above object, a high-frequency electric wave heating apparatus according to the present invention includes: electromagnetic wave emitting means for emitting electromagnetic waves, local heating means capable of heating an arbitrary portion of an object to be heated by the electromagnetic waves emitted by the electromagnetic wave emitting means, and control means for controlling the local heating means.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-frequency electric wave heating apparatus capable of heating an arbitrary portion of an object to be heated, and combining heating of the respective portions to make the entire heating distribution uniform.

It is another object of the present invention to provide a high-frequency electric wave heating apparatus capable of heating an arbitrary portion of an object to be heated and distinguishing a heated portion from an unheated portion.

It is another object of the present invention to provide a high-frequency electric wave heating apparatus which can maintain or improve heating efficiency and has higher reliability.

It is another object of the present invention to provide a high-frequency electric wave heating apparatus capable of automatically heating an arbitrary portion of an object to be heated according to a setting.

The high-frequency heating apparatus of the 1 st aspect of the invention comprises:

a heating chamber accommodating an object to be heated;

an electromagnetic wave emitting device that emits an electromagnetic wave;

a local heating means for concentrating the electromagnetic wave emitted from the electromagnetic wave emitting means on a part of the object;

a control device for controlling the local heating device and the electromagnetic wave emitting device;

characterized in that the control means controls the local heating means to change at least one of the electromagnetic wave emission direction with respect to the object and the object position with respect to the electromagnetic wave emission direction, thereby determining the position of the object concentrated on the electromagnetic wave, and controls the electromagnetic wave emission means to start and stop the emission of the electromagnetic wave, thereby selectively heating a desired portion of the object.

The high-frequency heating apparatus according to the 2 nd aspect of the invention is characterized in that the control means controls the local heating means after controlling the electromagnetic wave emitting means to reduce or eliminate the output.

The high-frequency heating apparatus according to the 3 rd aspect of the invention is characterized in that the control means controls the electromagnetic wave emitting means to increase the output after controlling the local heating means.

The high-frequency heating apparatus according to the 4 th aspect of the invention, further comprising setting means for allowing a user to make a setting, is characterized in that the control means controls the local heating means through the setting means.

The high-frequency heating apparatus according to the 5 th aspect of the invention is characterized in that the setting means has a first operation key for allowing a user to set at least one of a kind of an object to be heated, a heating output size, a heating time, and a heating method, and a second operation key for setting a start of heating, wherein the control means controls the local heating means and the electromagnetic wave emitting means through the first operation key and the second operation key, respectively.

The high-frequency heating apparatus according to the 6 th aspect of the invention is characterized in that the control means controls the local heating means to switch the electromagnetic wave in a direction in which an object to be heated is placed or in a direction in which an object to be heated is not placed.

The high-frequency heating apparatus according to claim 7 of the present invention is characterized in that the control device controls the local heating device to switch heating of a central portion of the bottom surface of the object to be heated or heating of a substantially peripheral portion of the object to be heated.

The high-frequency heating apparatus according to the 8 th aspect of the invention is characterized in that the control means controls the local heating means to switch the portion to be heated of the object in two-dimensional or three-dimensional space.

The high-frequency heating apparatus according to the 9 th aspect of the invention is characterized in that the control means controls the emission direction of the electromagnetic wave along a spiral trajectory by the local heating means.

The high-frequency heating apparatus according to the 10 th aspect of the invention is characterized in that the control means has intermittent control means which intermittently controls the local heating means so as to concentrate the electromagnetic waves at a limited portion.

The high-frequency heating apparatus according to the 11 th aspect of the invention is characterized in that the control means has continuous control means which continuously controls the local heating means so as to uniformly radiate the electromagnetic wave to a large area.

The high-frequency heating apparatus according to the 12 th aspect of the invention is characterized in that the control means has: intermittent control means for intermittently controlling the local heating means so as to concentrate the electromagnetic waves at a limited portion; a continuous control means that continuously controls the local heating means so as to uniformly radiate electromagnetic waves to a large area; and a switching control device that switches between the intermittent control device and the continuous control device.

The high-frequency heating apparatus according to the 13 th aspect of the invention is characterized in that the control means controls the local heating means to a predetermined position at least at the start of heating or the end of heating.

The high-frequency heating apparatus according to the 14 th aspect of the invention is characterized in that the predetermined position is a position suitable for the object to be light in weight or a position suitable for heating for a short time.

The high-frequency heating apparatus according to the 15 th aspect of the invention, further comprising a fan for sending air to the heating chamber, is characterized in that the control means controls the amount of air to be fed into the heating chamber.

Drawings

Fig. 1 is a structural diagram of a conventional high-frequency electric wave heating apparatus.

Fig. 2 is a structural diagram of another conventional high-frequency electric wave heating apparatus.

Fig. 3 is a structural diagram of another conventional high-frequency electric wave heating apparatus.

Fig. 4 is a structural diagram of another conventional high-frequency electric wave heating apparatus.

Fig. 5 is a structural diagram of another conventional high-frequency electric wave heating apparatus.

Fig. 6 is a structural diagram of another conventional high-frequency electric wave heating apparatus.

Fig. 7 is a sectional view of a main portion of the high-frequency electric wave heating apparatus shown in fig. 6.

Fig. 8 is a structural diagram of a high-frequency electric wave heating apparatus according to embodiment 1 of the present invention.

Fig. 9 is a main part configuration diagram of the high-frequency electric wave heating apparatus shown in fig. 8.

Fig. 10 shows a rotary waveguide and a driving unit thereof provided in the high-frequency heating apparatus shown in fig. 8, wherein (a) is a plan view of the rotary waveguide, (b) is a vertical sectional view of the rotary waveguide and the driving unit, and (c) shows a state in which a cam provided in the driving unit is engaged with a switch.

Fig. 11 is a bottom view of the high-frequency electric wave heating apparatus shown in fig. 8.

Fig. 12 shows a heating state of the food contained in the heating chamber of the high-frequency electric wave heating apparatus shown in fig. 8.

Fig. 13 shows the state shown in fig. 12 to a state in which the food and the waveguide are heated when they are rotated.

Fig. 14 is a characteristic diagram showing a food heating distribution when the states shown in fig. 12 and 13 are switched.

Fig. 15 shows a heated state of the food when the emitting port of the rotary waveguide is inclined at 45 ° with respect to the food.

Fig. 16 shows a heating state of the food product when the emitting port of the rotary waveguide is inclined by 45 ° with respect to the food product while stopping the rotation of the food product.

Fig. 17 is a bottom view of the turntable.

Fig. 18 is a cross-sectional view of a heating chamber of a high-frequency electric wave heating apparatus according to embodiment 2 of the present invention.

FIG. 19 shows embodiment 3 of the present invention, wherein (a) is a plan view of a rotary waveguide and (b) is a longitudinal sectional view thereof.

Fig. 20 shows embodiment 4 of the present invention, in which (a) is a plan view of a rotary antenna and (b) is a longitudinal sectional view thereof.

Fig. 21 shows embodiment 5 of the present invention, in which (a) is a plan view of a shielding member having an opening, and (b) is a longitudinal sectional view thereof.

Fig. 22 shows embodiment 6 of the present invention, in which (a) is a vertical sectional view and (b) is a transverse sectional view of a heating chamber of a high-frequency electric wave heating apparatus.

Fig. 23 is a structural diagram of a high-frequency electric wave heating apparatus according to embodiment 7 of the present invention.

Fig. 24 is a front view of an operation panel of the high-frequency electric wave heating apparatus of fig. 23.

Fig. 25 is a cross-sectional view of the high-frequency wave heating apparatus of fig. 23 in which the radiation port of the rotary waveguide is aligned with the center.

Fig. 26 is a cross-sectional view of the high-frequency heating apparatus of fig. 23 in which the radiation port of the rotary waveguide is directed to the wall surface of the heating chamber.

Fig. 27 is a characteristic diagram showing a relationship between a heating time and a food temperature in a conventional high-frequency electric wave heating apparatus.

Fig. 28 is a characteristic diagram showing a relationship between a heating time and a food temperature in the high-frequency electric wave heating apparatus of the present invention.

Fig. 29 is a characteristic diagram showing the switching time in the direction of the radio wave emitting port of the high-frequency radio wave heating apparatus according to the present invention.

Fig. 30 is a characteristic diagram showing a relationship between a heating time and a food temperature in the high-frequency electric wave heating apparatus according to embodiment 8 of the present invention.

Fig. 31 is a temperature characteristic diagram of dielectric loss of water.

Fig. 32 is a characteristic diagram showing a relationship between time and heating output when a frozen food is thawed using a conventional high-frequency electric wave heating apparatus.

Fig. 33 is a characteristic diagram showing switching times of the heating outputs of fig. 32.

Fig. 34 is a characteristic diagram showing a relationship between time and a food temperature when a frozen food is thawed using the high-frequency electric wave heating apparatus of the present invention.

Fig. 35 is a characteristic diagram showing switching times of the heating outputs in fig. 34.

Fig. 36 is a characteristic diagram showing a relationship between time and heating output in fig. 34 and 35.

Fig. 37 is a structural diagram of a high-frequency electric wave heating apparatus according to embodiment 9 of the present invention.

Fig. 38 is a cross-sectional view taken along line a-a' of fig. 37.

Fig. 39 is a characteristic diagram showing a change in the direction of the electromagnetic wave due to the operation of the rotary waveguide in fig. 38.

Fig. 40 is a structural diagram of a high-frequency electric wave heating apparatus according to embodiment 10 of the present invention.

Fig. 41 is a cross-sectional view of a lower portion of a heating chamber of the high-frequency electric wave heating apparatus of fig. 40.

Fig. 42 is a characteristic diagram showing a change in the direction of the electromagnetic wave due to the operation of the rotary waveguide in the configurations of fig. 40 and 41.

Fig. 43 is a longitudinal sectional view of a main part of a high-frequency electric wave heating apparatus according to embodiment 11 of the present invention, showing a state in which a rotary waveguide is lifted.

Fig. 44 shows a state in which the rotary waveguide descends in fig. 43.

Fig. 45 is a structural view of a high-frequency electric wave heating apparatus according to embodiment 12 of the present invention.

Fig. 46 shows two shield plates provided in the high-frequency heating apparatus of fig. 45, where (a) is a plan view of the 1 st shield plate and (b) is a plan view of the 2 nd shield plate.

Fig. 47 is a structural view of a high-frequency electric wave heating apparatus according to embodiment 13 of the present invention.

Fig. 48 is a cross-sectional view taken along line B-B' of fig. 47.

Fig. 49 shows detection positions of infrared detection elements provided in the high-frequency electric wave heating apparatus of fig. 47.

Fig. 50 is a block diagram of the high-frequency electric wave heating apparatus of fig. 17.

Fig. 51 is a characteristic diagram showing a change in the surface temperature of the food and a change in the temperature of a portion other than the food in the high-frequency wave heating apparatus of fig. 17.

Fig. 52 is a block diagram showing a modification of fig. 50.

Fig. 53 is a block diagram of a high-frequency electric wave heating apparatus according to embodiment 14 of the present invention.

Fig. 54 is a structural diagram of a high-frequency electric wave heating apparatus according to embodiment 15 of the present invention.

Fig. 55 is a cross-sectional view taken along line F-F' of fig. 54.

Fig. 56 is a structural diagram of a high-frequency electric wave heating apparatus according to embodiment 16 of the present invention.

FIG. 57 is a sectional view taken along line G-G' of FIG. 56, in which (a) shows a state where the 1 st opening is shielded and (b) shows a state where the 2 nd opening is shielded.

Fig. 58 is a block diagram of a high-frequency electric wave heating apparatus according to embodiment 17 of the present invention.

Fig. 59 is a temperature characteristic diagram for explaining the operation of the contour acquiring means provided in the high-frequency heating apparatus shown in fig. 58. (a) The graph shows the position of the food, (b) the detection position in the X direction, (c) the detection position in the Y direction, and (d) the combination of the detection position in the X direction and the detection position in the Y direction.

Fig. 60 is a block diagram of a high-frequency electric wave heating apparatus according to embodiment 18.

Fig. 61 is a block diagram of a high-frequency electric wave heating apparatus according to embodiment 19.

Fig. 62 is a structural diagram of a high-frequency electric wave heating apparatus according to embodiment 20 of the present invention.

Fig. 63 is a longitudinal sectional view of a main part of a high-frequency electric wave heating apparatus according to embodiment 21 of the present invention, showing a state where a turntable is raised.

Fig. 64 shows a state in which the turn table is lowered in fig. 63.

Fig. 65 is a bottom view of a turntable provided in a high-frequency electric wave heating apparatus according to embodiment 22 of the present invention.

Fig. 66 is a longitudinal sectional view of a main part of a high-frequency electric wave heating apparatus according to embodiment 23 of the present invention.

Fig. 67 is a structural diagram of a high-frequency electric wave heating apparatus according to embodiment 24 of the present invention.

Fig. 68 is a sectional view of a main part of a high-frequency electric wave heating apparatus according to embodiment 25 of the present invention, particularly showing a distribution state of an electric field.

Fig. 69 is a perspective view of a main part of a high-frequency electric wave heating apparatus according to embodiment 26 of the present invention.

Fig. 70 is a main part structural view of a high-frequency electric wave heating apparatus according to embodiment 27 of the present invention, showing a state in which two openings are shielded, (a) is a vertical sectional view thereof, and (b) is a plan view thereof.

Fig. 71 shows a state in which the other opening in fig. 70 is shielded, (a) is a longitudinal sectional view thereof, and (b) is a plan view thereof.

Fig. 72 is a reke (Rieke) diagram showing an operating point of a magnetron of the high-frequency electric wave heating apparatus shown in fig. 70.

Fig. 73 is a characteristic diagram showing a change in the output of the high-frequency radio wave heating apparatus, (a) showing a change in the output of the conventional apparatus, and (b) showing a change in the output of the apparatus of the present invention.

Fig. 74 is a structural view of a high-frequency electric wave heating apparatus according to embodiment 28 of the present invention.

Fig. 75 is a cross-sectional view taken along line P-P' of fig. 74.

Fig. 76 is a sectional view of the high-frequency electric wave heating apparatus according to embodiment 29 of the present invention corresponding to fig. 75.

Fig. 77 is a sectional view of the high-frequency electric wave heating apparatus according to embodiment 30 of the invention corresponding to fig. 75.

Fig. 78 is a characteristic diagram showing heating power of the high frequency electric wave heating apparatus according to the embodiments 28, 29 and 30, and is a Smith chart (Smith chart) showing a load adjustment state viewed from the magnetron.

Fig. 79 is a structural diagram of a high-frequency electric wave heating apparatus according to embodiment 31 of the present invention.

Fig. 80 is a longitudinal sectional view of a main portion of the high-frequency electric wave heating apparatus of fig. 79, showing a state in which a sealing portion is lowered.

Fig. 81 shows a state in which the sealing portion is raised in fig. 80.

Fig. 82 is a perspective view of a main part of a high-frequency electric wave heating apparatus according to embodiment 32 of the present invention.

Fig. 83 is a characteristic diagram showing unevenness of heating distribution when the milk is heated in the high-frequency electric wave heating apparatus of fig. 82.

Fig. 84 is a schematic longitudinal sectional view of the high-frequency radio wave heating apparatus under the optimum condition of fig. 83.

Fig. 85 is a characteristic diagram showing the uneven heating distribution when 100 g of sliced beef is thawed and frozen in the radio-frequency heating apparatus of fig. 82.

Fig. 86 is a schematic vertical cross-sectional view of the high-frequency radio wave heating apparatus under the optimum condition of fig. 85.

Fig. 87 is a characteristic diagram showing the uneven heating distribution when 300 g of sliced beef is thawed and frozen in the radio-frequency heating apparatus of fig. 82.

Fig. 88 is a schematic longitudinal sectional view of the high-frequency radio wave heating apparatus under the optimum condition of fig. 87.

Fig. 89 is a flowchart showing a procedure for determining an appropriate opening position and height in the initial state in the configuration of fig. 79 to 82.

Fig. 90 is a schematic view for simulating an electric field inside the high-frequency electric wave heating apparatus.

FIG. 91 is a characteristic diagram of a simulation result when only the 1 st opening is opened, and is a perspective view of a cross section taken along line S-S' in FIG. 90.

FIG. 92 is a characteristic diagram of a simulation result when only the 2 nd opening is opened, and is a perspective view of a cross section taken along line S-S' in FIG. 90.

Fig. 93 is a perspective view of a flat food heated inside the high-frequency electric wave heating apparatus of fig. 90.

FIG. 94 is a characteristic diagram of a simulation result when only the 1 st opening is opened, and is a perspective view of a cross section taken along line U-U' in FIG. 93.

Fig. 95 is a characteristic diagram of a simulation result when only the 2 nd opening is opened, and is a perspective view of a cross section taken along line U-U' in fig. 93.

Fig. 96 is a vertical cross-sectional view of an essential part of the high-frequency electric wave heating apparatus for explaining propagation of an electromagnetic wave in the waveguide.

Fig. 97 is a structural diagram of a high-frequency electric wave heating apparatus according to embodiment 33 of the present invention.

Fig. 98 is a cross-sectional view taken along line V-V' of fig. 97.

Fig. 99 is a cross-sectional view taken along line W-W' of fig. 97.

Fig. 100 is a characteristic diagram showing how an electric field is bent in the high-frequency electric wave heating apparatus shown in fig. 97.

Fig. 101 is a cross-sectional view of a heating chamber for explaining how the electric field is established in a certain high-frequency wave heating apparatus by the influence of the position of an opening on a wall surface.

Fig. 102 is the same as fig. 101 when the position of the opening is changed.

Fig. 103 is the same view as fig. 101 when the position of the opening is changed again.

Fig. 104 is the same view as fig. 101, except that the position of the opening is changed.

Fig. 105 is a characteristic diagram showing the heating efficiency of the high-frequency electric wave heating apparatus according to embodiment 34 of the present invention, and is a Smith chart (Smith chart) showing an adjustment state viewed from the magnetron.

Fig. 106 is a plan view of some trades on a placed tray.

Fig. 107 is a characteristic diagram showing temperature variations at the time of burning and selling of the heating map 106 in the conventional high-frequency electric wave heating apparatus.

Fig. 108 is a characteristic diagram showing temperature variations at the time of burning and selling of the heating map 106 in the high-frequency electric wave heating apparatus of the present invention.

Fig. 109 is a characteristic diagram showing temperature variations at the time of burning and selling of the heating map 106 in another high-frequency electric wave heating apparatus according to the present invention.

Fig. 110 is a cross-sectional view of a high-frequency electric wave heating apparatus according to embodiment 35 of the present invention.

Fig. 111 is a characteristic diagram of a high-frequency electric wave heating apparatus according to embodiment 36 of the present invention, and is a smith chart when the adjustment state of the 1 st opening is deviated.

Fig. 112 is a cross-sectional view of a high-frequency electric wave heating apparatus according to embodiment 37 of the invention.

FIG. 113 is a cross-sectional view taken along line Y-Y' of FIG. 112.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

Electromagnetic waves emitted from a magnetron 2 as a representative electromagnetic wave emitting means are incident into a heating chamber 4 through a waveguide 3 and a power feeding chamber 15, and heat food 6 as an object to be heated in the heating chamber 4. Since the electromagnetic wave in the waveguide 3 locally heats an arbitrary portion of the food 6 by the rotary waveguide 8 as a radiation portion disposed in the feed chamber 15, the waveguide 3 and the rotary waveguide 8 are collectively referred to as local heating means 16. The rotary waveguide 8 has directivity to the emission direction of the electromagnetic wave, and the emission direction of the electromagnetic wave is switched by a rotary method to realize local heating. Therefore, the rotary waveguide 8 is so structured that an electromagnetic wave coupling portion, which is coupled to the waveguide 3 to extract an electromagnetic wave, is called a coupling portion 7, and transits to the waveguide 3 and the feeding chamber 15 (the heating chamber 4 when the feeding chamber is not provided), and further includes an emission port 17 for emitting the extracted electromagnetic wave.

The coupling portion 7 is connected to a motor 18 as a driving means, and is rotatable by the motor 18, so that the rotary waveguide 8 itself is rotationally driven around the coupling portion 7. The control means 19 controls the motor 18 to control the direction of the electromagnetic wave determined by the emission port 17 of the rotary waveguide 8, thereby controlling the local heating.

To heat any portion of the food 6, the food is placed in a pan 21 on a stage 20. The stage 20 is composed of a turntable 1 having a metallic electromagnetic wave shielding part and a glass or plastic plate 21 placed thereon as an electromagnetic wave transmitting part, and is driven as a whole by a motor 22 as stage driving means. At this time, the control unit 19 detects the weight of the food 6 by the weight sensor 23 as a weight detecting means of the food 6 while driving the motor 22, and performs control corresponding to the detected weight (control of the driving time, heating output, estimated heating end time, and the like of the rotary waveguide 8). At this time, the rotation center of the stage 20 is located at the center 24 of the bottom surface of the heating chamber 4, and the heating in the rotation direction is made uniform by a constant rotation, or the heating is stopped and decelerated at a predetermined position to perform local heating. On the other hand, the rotation center of the rotary waveguide 8 is located at a position deviated from the center 24 of the bottom surface of the heating chamber 4. The direction in which the emitting port 17 is directed toward the food 6 can be changed to change the emitting direction of the electromagnetic wave, thereby enabling switching, or heating the center of the food 6, or heating the periphery thereof, in other words, the heating portion in the radial direction of the stage 20 can be changed. So that any position on the stage 20 can be heated in accordance with the rotation of the turntable 1.

Here, the rotation center of the stage 20 is located at the center 24 of the bottom surface of the heating chamber 4, and thus the size of the stage can be made large, and a large food can be placed or more foods can be placed.

The center of the stage 20 is aligned with the rotation center, and the vertical movement of the object-carrying surface during rotation is controlled to perform stable driving, thereby facilitating local heating of the aimed portion. And the vibration of the food 6 is not easily caused and the food is not easily spilled out.

In general microwave ovens, in order to cover the opening through which electromagnetic waves enter, an opening cover made of a low-loss material that does not easily absorb electromagnetic waves is often used to cover the opening from the heating chamber side, but in this embodiment, a cover 25 is provided as a protective means for protecting the local heating means 16 to cover the feeding chamber 15, and there is no unevenness on the bottom surface of the heating chamber.

However, the lid 25 of the present embodiment is slightly different from the existing open lid in details, and is supplemented here.

The existing opening cover often has the condition that a user can not stretch the hand into the opening cover or the opening is dirty. In this embodiment, however, the rotating waveguide must be controlled in accordance with the aim in order to locally heat the food. That is, scattering of the food stuff 6 is prevented from directly hitting the rotary waveguide 8 to be inactive, or the food stuff 6 is accumulated in the vicinity of the waveguide 8 to absorb electromagnetic waves in the same manner, so that the targeted portion cannot be heated. In short, the effect of preventing the local heating by the local heating means 16 from being hindered is obtained.

The control unit 19 monitors a temperature change of the food 6 by means of a temperature sensor 26 as a temperature distribution detection means for detecting the temperature of the food 6, and controls the emission of electromagnetic waves from the magnetron 2, the operation of an electric fan 27 for cooling the magnetron 2, and the operation of various heating elements, in addition to the above control.

In general, when the heating element 28 is used, the temperature in the heating chamber 4 rises to about 300 ℃, and the plate 21 is a glass plate, which has a limited heat resistance temperature and is often replaced with a metal plate. In order to eliminate the trouble of replacing the tray 21 by electromagnetic wave heating or heating element heating, a ceramic tray having a high heat-resistant temperature may be used in both cases.

The temperature sensor 26 detects the temperature of the food 6 from the opening 29 in the wall surface of the heating chamber 4 to detect the heating distribution, and the structure of the temperature sensor 26 itself will be described below. A typical temperature sensor 26 for detecting temperature in a non-contact manner is an infrared sensor for converting infrared energy emitted from the food 6 into an electric signal. The infrared sensor includes a pyroelectric element (pyroelectric element) having a hot junction and a cold junction inside, a pyroelectric type having a chopper, and the like, and any of them can be used in the present invention.

Fig. 9 is a main structure diagram showing a positional relationship between the magnetron 2 and the rotary waveguide 8.

Distance l for allowing electromagnetic wave emitted from antenna 30 of magnetron 2 to reach coupling portion 7 of rotary waveguide 8₁Is an integral multiple of g/2, g being the in-tube wavelength in the waveguide 3. This is because the electromagnetic wave in the waveguide 3 becomes a standing wave whose intensity is periodically repeated, and its wavelength coincides with g. The magnetic field of the antenna 30 of the magnetron 2 is always strong. Accordingly, with the above-described configuration in the dimensional relationship, the coupling portion 7 of the rotary waveguide 8 can be made to be a strong electric field, and the electromagnetic wave in the waveguide 3 can be efficiently guided out of the waveguide 3.

Further, when the distance from the antenna 30 of the magnetron 2 to the end 31 of the waveguide 3 and the distance from the joint 7 to the end 32 of the waveguide 3 are set to be approximately odd times (1 time in the figure) of g/4, a more stable standing wave can be generated in the waveguide.

This is because, when a standing wave is generated, a position at an odd multiple of g/4 from a position where the electric field is strong is supposed to be a position having an end face where the electric field is weak.

Further, in the present embodiment, even if the rotary waveguide rotates, the distance from the antenna 30 of the magnetron 2 to the joint 7 is generally constant, having an effect of generating a stable standing wave.

The electromagnetic wave extracted from the coupling portion is emitted from the coupling portion 7 into the heating chamber through the emission port 17, and the distance l is set to be longer₂Is an element for determining the directivity, and therefore can be appropriately changed as needed. However, if l is made₂The electric field intensity of the emitting port 17 can be made large as an integral multiple of g/2, and the efficiency is extremely high when the food 6 is placed close to the emitting port according to the formula (1).

Furthermore, let l in the figure₃And l₄Satisfy l₃＞＞l₄So as to make the electromagnetic wave easily shoot towards₃One side, and then₅The odd multiple of g/4 makes the electromagnetic wave more easily to emit to l₃One side.

The emission direction of the electromagnetic wave is controlled in such a structure.

Further, since the distance from the antenna 30 of the magnetron 2 to the emission port 17 is always constant, the impedance therebetween is also always constant, and the adjustment state is easily maintained, thereby having an effect of maintaining high heating efficiency.

Fig. 10 is a main structure view of the rotary waveguide 8.

(a) Is a top view, and (b) is a cross-sectional view seen from the side. In (a), with l₀Is the wavelength of electromagnetic wave in vacuum (or air), then₆Is composed of

l₆＞λ₀2 (at 2.45GHz,. lambda.₀A/2 of about 61 mm)，

The electromagnetic wave is reliably emitted. In fact, there is room for l₆And finally taking over 65 mm.

The rotary waveguide is supported at three points by two blocks 33 made of teflon plastic shown in (a) and (b) and a fitting portion 35 provided on a shaft 34 of the motor 18, so that the rotary waveguide can be rotated stably.

The pad 33 has a downward curved surface and is easy to slide. The material of the pad 33 may be any material as long as it can have a supporting effect, is smooth and easy to rotate, and has no conductivity, and if a conductive material is used, it can be realized by taking measures to prevent sparks from occurring between the pad and the bottom 36 (for example, the pad is usually attached to the bottom 36 without a gap).

(c) The figure shows a cam 37 connected to the shaft 34 and a switch 38 as a position detecting means. The rotary waveguide 8 is driven to rotate by the motor 18, and the convex portion 39 of the cam 37 presses the button 40 of the switch 38 once per one rotation of the shaft 34, so that the rotational position can be known from the driving time after the button 40 is pressed, in addition to detecting the emission direction of the electromagnetic wave, the aiming direction can be controlled. The control means 19 determines the rotation time of the motor 18 based on the signal from the switch 38, and controls the emission direction of the electromagnetic wave from the emission port 17. Of course, it is conceivable to use a stepping motor for the rotation control of the motor 18 in order to perform more accurate position control and fine control such as changing the rotation speed.

When the heating is started at a predetermined reference position, or when the heating is terminated, the heating may be controlled to move to the reference position.

If the heating is started, the part to be aimed with high precision can be heated, and if the heating is ended, the procedure of confirming the reference position in the next heating can be omitted, and each effect is achieved.

Fig. 11 is a main part configuration diagram of the high-frequency electric wave heating apparatus of the present embodiment, and is a diagram of the bottom surface of the heating chamber 4 of fig. 8 as viewed from the lower side. The heating elements 28A, 28B, and 28C are disposed in the empty space, so that the power feeding chamber 15 and the weight sensor 23 can coexist.

And for this reason it is preferable to make the shape of the rotary waveguide 8 small. Therefore, the rotary waveguide 8 is preferably small and has high directivity.

Fig. 12 and 13 are sectional views of essential parts of the high-frequency electric wave heating apparatus according to the present embodiment, showing the food 6 viewed from above as a section of fig. 8. In order to show the directivity of the rotary waveguide, the flat rectangular parallelepiped food 6 is rotated together with the plate 21 at a constant speed, the rotary waveguide 8 is stopped as it is at the position of fig. 8, and the result when heating is performed with a constant heating output is the heating part 41 shown in the figure. However, for easy understanding, the portions that are actually hidden from view by the tray 21 are also shown by solid lines. Regarding the orientation (directivity) of the emitting port 17, fig. 12 shows the center of the dish 21, and fig. 13 shows the outward direction rotated 180 degrees compared to fig. 12.

In fig. 12, since the electromagnetic wave 42 is emitted from below, the heating portion 41 appears at a substantially central portion of the food 6.

In fig. 13, since the electromagnetic wave 42 enters the food 6 after being reflected by the wall surface of the heating chamber 4, the heating portion 41 appears at the edge (periphery) of the food 6. In the conventional microwave oven, since the electromagnetic wave is reflected on the wall surface of the heating chamber before entering the food, the result similar to that of fig. 13 is obtained.

Fig. 14 is a structural diagram showing the heating distribution of the food 6, and shows the result of switching the states of fig. 12 and 13 (switching the direction of the emitting port 17 at an appropriate ratio). The heating part 41 is formed at the center and the periphery of the food 6, and it is known that the heating uniformity is considerably improved as compared with the conventional microwave oven. However, in this case, an unheated portion 43 that is not easily heated remains in the intermediate region between the center and the periphery. The method of local heating of this portion is explained below.

Fig. 15 and 16 are sectional views of essential parts of the high-frequency electric wave heating apparatus according to the present embodiment, and are the same as fig. 12 and 13, showing the cross section of fig. 8. As a heating method of heating the unheated portion 43 of the intermediate zone as shown in fig. 14, it is easy to imagine that the direction of the emission port 17 is selected to be a position between the center (0 °) and the outside (180 °), but heating is not performed well in practice if the turntable is rotated at a certain speed. Even if the test is carried out by changing the orientation of the emission port slightly, the periphery is almost heated as long as the center is not heated. For example, in the case where the emission port 17 is 45 °, the results shown in fig. 15 are obtained. The reason for this is that the tray 21 rotates at a constant speed and the heating output is constant. Since the middle area is heated instantaneously even when the food 6 is rotated, and the periphery of the food 6 is heated at the other time, the periphery is heated on average in one cycle. Therefore, it is understood that in order to heat the intermediate region, it is necessary to keep the state in which the intermediate region can be heated and avoid the other state. Fig. 16 shows the result of the state in which the rotation of the tray 21 is stopped and the intermediate region can be heated. The discharge port 17 is set at 45 °, the food 6 is stopped at the position shown in the figure, and one of the unheated portions 43 of fig. 14, which is difficult to heat, is heated. In order to heat the other side of the unheated portion 43, the food 6 may be rotated by 180 ° again. As a result, four operations are required to uniformly heat the entire food 6 by moving the food by 180 ° in fig. 12, 13, and 16. However, even if the rotation of the dish 21 is not completely stopped during the heating, the rotation may be decelerated in the vicinity of a state where the intermediate region can be heated.

The plate 21 may be rotated at a constant rotation speed to increase the heating output in the state where the intermediate region can be heated, compared with the heating output in the other state. In practice, a method of making the heating output in a state capable of heating the middle area to the total power and making the heating output in the other state to 0 or low power is considered.

The rotation of the plate 21 and the control of the heating output can also be carried out in combination.

Further, in order to locally heat an arbitrary position by the above method, it is sufficient to comprehensively control three important members of the rotary waveguide 8, the plate 21, and the magnetron 2.

Fig. 17 is a main part configuration diagram of the high-frequency electric wave heating apparatus of the present embodiment, and shows a configuration of the turntable 1 as viewed from below. The turntable 1 is made of metal and includes wheels 44 and 45, shafts 46 and 47, and a bearing 48 in order to withstand the heat of the heating elements 28A, 28B, and 28C. Further, a distance l in the rotational direction of the perforated portion of the turntable 1₇、l₈Each of the electromagnetic waves has a length of 1/2 or more, and has a structure that electromagnetic waves easily transmit therethrough.

In addition to the directivity of the rotary waveguide 8, it is necessary to heat the center of the bottom surface of the food as shown in fig. 17₈That is, the opening is formed near the center of the bottom surface, and the like l is formed so as to heat the periphery of the food₇That requires a peripheral opening. It is also clear that if the turntable 1 is made of a material that is difficult to absorb electromagnetic waves and that can transmit electromagnetic waves, such as ceramics, it is not necessary to provide an opening.

For this reason, a material that can withstand heating of the lower heating elements 28A, 28B, and 28C is selected, or a heating element (hot air circulation type heating element) that does not increase the temperature of the bottom surface side too high is used instead of the lower heating elements 28A, 28B, and 28C, or some material that transmits electromagnetic waves may be used.

Fig. 18 shows the 2 nd embodiment.

The rotary waveguide 8 is formed at a corner of the heating chamber 4, and there is an effect of increasing the degree of freedom such that the size of the rotary waveguide can be slightly increased.

However, as shown in fig. 18, the driving range of the emission port 17 is only inside the bottom surface of the heating chamber 4. If the driving range is set to the outside of the bottom surface of the heating chamber 4, the high-frequency electric wave heating apparatus becomes large in size and needs to be prevented from leaking out separately. It is to prevent these problems that the above-described structure is adopted.

Fig. 19 is embodiment 3. This is an example in which the same effect is obtained by changing the shape of the rotary waveguide 8, and (a) shows that the end surface of the rotary waveguide 8 is bent in all four directions, and the electromagnetic wave is emitted from the opening 49. The curved ends are rounded to improve the spark prevention effect.

In this case, the electromagnetic wave tends to be emitted directly above the opening 49 as compared with embodiment 1.

The inner space 50 may be considered as a waveguide. Thus, the distance l from the joint 7 to the end face₅And l₉+l₁₀Taking an approximately odd multiple of g/4, respectively, standing waves can be stably generated.

Secondly, if l is taken₉Is about an odd multiple of g/4. Get l₁₀About an integral multiple of g/2, there is an effect of generating a more stable standing wave.

This will be described below with reference to (b). This is a diagram showing an electric field generation pattern at a certain instant. In practice, the inversion is repeated in a period that is the inverse of the frequency. The 1 st solid-line arrow indicates a representative direction of the electric field 51a, and three peaks of standing waves (antinodes of the electric field) are present in the internal space 50. In the 2 nd place, an electric field 51b indicated by solid arrows is generated in the vicinity of the opening, and therefore a strong electric field 51c is formed above the opening 49 so as to sandwich the opening 49.

The above two cases occur simultaneously because the above dimensional relationship is satisfied, and there is an effect that emission of electromagnetic waves from the openings 49 can be achieved without disturbing the standing wave.

Fig. 20 shows embodiment 4, in which a rotary antenna is used instead of a rotary waveguide.

The plate-like object 53 (specifically, iron and stainless steel) having conductivity connected to the joint 7 has directivity, and the same effect is expected.

Fig. 21 shows an example 5 in which the opening closing site is switched.

The plate-like object 54 having conductivity connected to the joint 7 has an opening 55 and the other portions are covered.

Since the opening 55 is provided, directivity is provided, and the same effect can be expected. However, the aimed directivity is not as easy to obtain with the structures of embodiment 4 and embodiment 5 as in embodiments 1 to 3. On the contrary, the structure itself without bending can achieve the effect of simplifying the structure.

Fig. 22 shows the 6 th embodiment.

The stage 20 is constituted by a glass plate 21 and a roller-carrying ring 56, and the plate has a recess 57 and is rotatably supported by the roller-carrying ring 56 in cooperation with a shaft 58 of another member.

(a) The sectional view is shown, and (b) is a main part structure view when the ring with the roller is viewed from above in a plan view.

The roller-carrying ring 56 has a ring 59 and three rollers 60, both of which are formed using a material that is permeable to electromagnetic waves.

Due to the above structure, the electromagnetic wave emitted from the rotary waveguide 8 can enter the food 6 without being affected. Thereby having the effect of easily heating the targeted local area. And a depression (not shown) is formed in the bottom surface of the heating chamber forming the passage to smoothly roll the roller without position deviation.

Fig. 23 to 29 show embodiment 7. First, in fig. 23, the rotary waveguide 8 is projected into the heating chamber 4. In this case, the cover 25 is formed in a box shape to protect the rotary waveguide 8.

This structure has the effect of reducing the size of the lower portion of the heating chamber 4, but also has the problem of reducing the effective volume of the heating chamber 4

In this embodiment, the food 4 is provided with the photo sensors 61 and 62 as shape detecting means, and the shape of the food can be determined based on whether or not the light receiving unit receives the light emitted from the light emitting unit 61.

If the temperature of the food 6 is the same as the temperature of the dish 21, the presence area of the food 6 cannot be instantaneously judged using the temperature sensor 26, but it is possible to determine the presence area of the food 4 before heating using the information of the light sensors 61 and 62 and the weight sensor 23.

Thus, if only the region where the food 4 exists is heated, the portion where the food 4 does not exist is not heated to be wasted, so that the efficiency can be improved.

In this case, the apparatus further includes a setting means 63 which can be input and set by the user.

Although the place to be locally heated may be determined only based on the input content, the direction of the rotary waveguide 8, the rotation of the turntable 1, the output of the magnetron 2, and the like are generally controlled based on the input content and information from the temperature sensor 26, the light sensors 61 and 62, the weight sensor 23, and the like, and the determination by the area determination control means (not shown) in the control means 19.

Fig. 24 is a main part configuration diagram of the high-frequency electric wave heating apparatus of the present embodiment, and shows an operation panel 64 as a setting means 63.

First, in the case of heating milk, after milk is put into the heating chamber 4, the milk key 65 is pressed, and then the start key 66 is pressed. Then, the control means 19 determines that the food 6 is milk based on the signal from the control panel 64, determines the amount, shape, placement position and initial temperature of the milk based on the signals from the weight sensor 23, the light sensors 61 and 62 and the temperature sensor 26, determines the position of the appropriate emitting port 17, calculates how much movement is required from the reference position, drives the motor 18 based on the result, and then the magnetron 2 starts emitting electromagnetic waves.

At this time, when the milk is placed near the emission part, the rotation of the turntable 1 is stopped and the rotary waveguide 8 is moved to heat the milk directly below.

When the milk is placed at a position (for example, on the opposite side of the shaft 67 with respect to the motor 22) where the milk is separated from the emission port 17, it is sufficient to control both the turntable 1 and the rotary waveguide 8 to move in a positional relationship in which the milk can be heated directly below.

On the other hand, when milk is placed in the center of the turn table 1, there is little difference between turning the turn table 1 and stopping it, and it is natural to heat the milk directly below the turn table by directing the electromagnetic wave toward the center with the rotary waveguide 8, as shown in fig. 25.

When several cups of milk are placed, the turntable 1 and the rotary waveguide 8 are both moved to heat the milk directly below the several cups in sequence.

In the case of milk, if the electric field is concentrated on the bottom surface, the result of good distribution can be obtained naturally due to convection, and the matching state is good, so that the heating efficiency is remarkably improved.

Under the condition that the same result is obtained when the turntable moves and stops, the electric power can be saved by stopping the turntable, and the energy-saving effect is achieved.

Once heating has taken place, heating is then carried out using the times determined by the weight sensor 23 and the light sensors 61, 62, or heating is terminated when it is determined from the temperature sensor 26 that the milk has reached a suitable temperature.

Here, when the turntable 1 and the rotary waveguide 8 are repeatedly driven and stopped a plurality of times, the impedance seen from the magnetron 2 during driving changes, and therefore the operation may be somewhat unstable. Therefore, when the oscillation of the magnetron 2 is stopped or the output is reduced before the driving, and when the oscillation of the magnetron 2 is performed and the output is increased after the turntable 1 and the rotary waveguide 8 are stopped, the operation state of the magnetron 2 can be stabilized, and the effect of reducing unnecessary radiation noise from the magnetron can be obtained.

When small solid food 6 such as potato is heated, if only electromagnetic waves are let in from below, only the heat is from below because there is no convection. Therefore, as shown in fig. 26, it is also effective to emit electromagnetic waves in a direction where the food 6 is not present, that is, to heat the food by electromagnetic waves reflected by the wall surface of the heating chamber 4 while avoiding local heating.

Next, a case where a plurality of flat foods 6 such as shaomai and pizza are heated will be described.

Fig. 27 is a characteristic diagram of a case where a conventional microwave oven is generally used, in which the horizontal axis represents heating time and the vertical axis represents temperature T of food 6.

The average temperature of the peripheral portion of the food 6 is approximately indicated by Tout, while the average temperature of the central portion is approximately indicated by Tin, and the target average temperature Tref at the end of heating is 80 ℃. Tout rises rapidly as heating begins, while Tin does not rise easily. After t1, Tout reaches Tref and after t2 the saturation temperature (boiling temperature) is reached, and if heating is stopped at this time, the problem occurs that the temperature of Tin is too low. Therefore, the heating is continued until the heating is ended at time T3 in which the Tin is approximately within the allowable range. At this time, the peripheral portion of the food 6 is overheated (Tout is greater than Tref) and the central portion is insufficiently heated (Tin is less than Tref), so that the food is cooked very poorly.

On the other hand, fig. 28 is a characteristic diagram of the present embodiment, and the direction of the emitting port 17 is switched only once in the middle to confirm the effect of the uniform heating. First, at the start of heating, the direction of the emitting port is set to the same direction as in fig. 12 or fig. 25, and the food 6 is heated at the center portion thereof, and at t4, the direction of the emitting port is rotated by 180 ° and switched to the same direction as in fig. 13 or fig. 26. Once heating is started, before t4 is reached, Tin temperature rises fast and Tout rises very slowly, and after t4, the rate of temperature rise is reversed and Tout becomes more likely to rise than Tin. Thus, if the heating is ended at t5, both the peripheral portion and the central portion of the food reach a positive proper overheat state (Tout * Tin * Tref), the effect is very good. In addition, the portion not excessively heated at this time has a small heating loss, and the heating can be terminated in a short time (t5 is less than t 3).

Fig. 29 is a characteristic diagram showing how the switching time of the direction of the radio wave emitting port 17 in fig. 28 is determined. The horizontal axis represents the weight m of the food 6 detected by the weight sensor 23, and the vertical axis represents the time t. Since the heating time optimal for the weight of the food 6 is longer, there is a method of calculating in the control means 19 the switching time t4 of the discharge port 17 as a function of m. Of course, the heating termination time t5 may be determined in the same manner.

There are of course other ways to perform the same handover. As shown in fig. 30 of embodiment 8, the switching time of the emitting port 17 is feedback-controlled by the temperature of the food 6 itself. This is somewhat different from fig. 28 in that the temperature of the food product 6 is monitored in real time by the temperature sensor 26 and the emitting port 17 is switched if Tin reaches Tk (Tk is a value determined in the control means and is a temperature lower than Tref). And thereafter continues to monitor the temperature, and control stops heating at instant t6 when the temperature of the food product 6 actually reaches Tref. The actual measurement of the temperature of the food 6 by the temperature sensor 26 can be said to be more accurate than the method of estimating the weight m.

As described above, it is needless to say that there is no need to limit the switching to one time, and it is preferable that the temperature difference is not easily increased by the switching repeatedly, and if the temperature is actually measured, it is more preferable that the part is locally heated as soon as the place where the temperature is low is found.

In any food 6, in order to constantly achieve uniform heating and eliminate unevenness of heating distribution, information such as the direction of the emitting port, the rotation of the turntable 1, and the time for switching the oscillation and combination of the magnetron 2, which are most suitable for the conditions such as the material, shape, placement position, and temperature of each food 6, may be stored in advance in a microcomputer in the control means 19 as a database. In the present embodiment, by adopting such a method, the input of the operation panel 64 and the outputs of the temperature sensor 26, the weight sensor 23, the light sensors 61 and 62, etc. are compared with the database by the control means 19, and the control capable of obtaining the most appropriate heating can be realized.

Next, FIGS. 31 to 36 show an example of thawing of the food 6 in a frozen state (-20 ℃ C.).

FIG. 31 shows dielectric loss ε of water_rtan δ temperature profile. The horizontal axis represents the temperature T of water, and the vertical axis represents the dielectric loss ε_rtan delta. The dielectric loss of frozen water (ice at 0 ℃ C. or lower) is small, and the dielectric loss of molten water (at 0 ℃ C. or higher) is extremely increased (about 1000 times). On the other hand, as shown in formula (1), the power absorbed per unit volume by electromagnetic waves is proportional to ∈ r tan δ. Therefore, the melted portion is extremely likely to absorb electromagnetic waves, and if the heating is continued in the original state, the temperature difference is further increased as the heating is continued when the thawing is continued. In short, when only a part of water is melted, temperature unevenness inevitably occurs by continuing electromagnetic wave heating with the original heating distribution.

Thus, it is necessary to perform detailed control.

When the user defrosts meat and fish, the user puts the food 6 into the heating chamber 4, presses the defrosting button 68 shown in fig. 24, and then presses the start button 66. Then, the control means 19 determines that the food 6 is frozen food based on the signal from the operation panel 64, determines various states such as the number, shape, placement position, and initial temperature of the frozen food based on the signals from the weight sensor 23 and the optical sensors 61 and 62, determines an appropriate number of rotations of the rotary waveguide 8, drives the motor 18 to rotate, and starts to emit electromagnetic waves from the front and rear magnetrons 2. At this time, the rotary waveguide 8 rotates and the turntable 1 also rotates, so that the electric field is prevented from concentrating on a certain portion as much as possible.

When the temperature unevenness starts to occur as described above, the rotary waveguide 8 is repeatedly controlled so that the position of the emission port 17 is stopped facing the low temperature portion to locally heat the low temperature portion of the food. Here, the control means 19 includes continuous control means for continuous rotation, intermittent control means for intermittent operation, and switching control means for switching the two means in the middle of the operation, and is easy to control.

However, since the temperature of the portion exceeding 0 ℃ rapidly rises once, it may not be sufficient to locally heat the low-temperature portion to make the low-temperature portion uniform.

Therefore, the control of the rotary waveguide 8 in conjunction with the output control of the magnetron is improved, and an example of combination with the output control of the magnetron 2 will be described below.

Fig. 32 and 33 are characteristic diagrams of a conventional microwave oven.

Fig. 32 is a characteristic diagram showing a change in heating output of the magnetron 2 when the frozen food 6 is thawed. The horizontal axis represents time T, and the vertical axis represents output P. The heating is performed at a continuously high output during a time t7 in the initial stage of heating, the output is reduced at t8, the operation is switched to the intermittent heating operation, and finally the ratio of heating to stop heating is changed at t9 to reduce the average output. Simply to slowly reduce the output. The decrease in output slows down the temperature rise due to electromagnetic wave heating, and the rate of temperature rise due to heat conduction inside food 6 and the difference in ambient temperature between food 6 and inside heating chamber 4 increases, thus providing a slight effect of improving temperature unevenness.

Fig. 33 is a characteristic diagram showing how t7, t8, and t9 in fig. 32 are determined. The horizontal axis represents the weight m, and the vertical axis represents the time t. Here, the switching time of the output power is determined only by m regardless of the storage state of the food 6 before heating detected by the weight sensor 23. For example, if the holding temperature before heating is high, a part of the food may be melted and boiled before t 7. And thus should be actually corrected based on the output of the temperature sensor 26. Of course, since the heating under a certain heating distribution is not changed, the elimination of the temperature unevenness is less desirable.

Fig. 34 to 36 are characteristic diagrams of the high-frequency electric wave heating apparatus of the present embodiment.

FIG. 34 shows a state in which the rotational waveguide 8 is rotated at a constant speed by the continuous control means during thawing of the frozen food 6, and stopped at a position where the low-temperature portion can be heated at the discharge port 17 by the switching control means and the intermittent control means in the middle of the processTemperature characteristic diagram of (1). The horizontal axis represents time T, and the vertical axis represents temperature T. First, the rotary waveguide 8 and the turntable 1 are rotated at a constant speed to start heating. Then, the temperature T at the high temperature portion is set to 0 ℃ as the set temperature Tk shown in fig. 30_HITo reach T_HIAt time t10 equal to Tk, heating is stopped, and the emitter port 17 and the turntable 1 are stopped in a state where they can heat the low-temperature portion, or decelerated when they approach this state. Then stopping the emission of electromagnetic waves or greatly reducing the output in the time of ts, and waiting for the temperature T of the low-temperature part_LOWThere is a certain rise, and the output is increased again from t11 to heat.

At this time, the heating portion is changed to the low temperature portion T by the emitting port 17 and the turntable 1_LOWRising quickly, T_HIFollowed by it. Then at T_HI≌T_LOWWhen the value of ≈ Tref is equal to or greater than t12, the heating is terminated. As a result, the temperature averaging effect by the waiting time ts and the effect by the heating distribution switching make the thawing effect excellent and the temperature distribution uniform.

Fig. 35 is a characteristic diagram showing how ts, t11, and t12 in fig. 34 are determined. The horizontal axis represents weight m, and the vertical axis represents time t. Here, ts, t11, and t12 are defined as functions of the weight m of the food 6 detected by the weight sensor 23. Of course, there is a method of determining the output of the temperature sensor 26 while correcting it, and a heating system that makes heating more uniform is considered to be preferable.

Fig. 36 is a characteristic diagram showing a change in heating output of the magnetron 2 when the frozen food 6 shown in fig. 34 and 35 is thawed. The horizontal axis represents time t, and the vertical axis represents output P. The heating is performed at a continuous high power output for a time t10 at the initial stage of heating, and then no output is performed for a time ts, and then a small output is used until the last t12, and the operation is switched to an intermittent operation to lower the average output.

In the present embodiment, the electromagnetic wave heating is stopped, or the rotary waveguide 8 is driven when the output is greatly reduced, so that the radiation is canceled and the temperature rise of the magnetron 2 can be suppressed, as compared with the conventional electromagnetic wave stirring that uses a stirrer and a rotary waveguide and is constantly rotated at a constant speed.

In addition, when the electromagnetic wave radiation from the magnetron 2 is unstable, for example, when the operation of the magnetron 2 is changed from off to on or the rotary waveguide 8 is performing a switching operation, the output of the sensor is not received in order to prevent the influence of the high-frequency electromagnetic wave on the noise of the various sensors, and thus, it is possible to realize a more accurate control.

The local heating section may be controlled by calculation processing in the control means 19 based on setting input set by the user and output of various sensors.

For example, the switching time of the local heating unit may be determined according to a menu, a maximum temperature, a difference between the maximum temperature and the minimum temperature, or a change rate with respect to time.

In addition, in the case of cooking a plurality of kinds of food 6 at the same time, much more consideration is given.

For example, when there are food to be heated and food such as lettuce which is not to be heated, it is necessary to heat only the food to be heated locally.

For this reason, there is a method in which a user sets a region to be heated after determining a place to place. On the other hand, if there is a sensor or the like for detecting the material and cooking content of the food, the determination can be automatically made.

Fig. 37 to 39 show an example 9 in which a stage 20 fixed without a turntable is provided and a rotary waveguide 8 is controlled in 2 dimensions.

The rotary waveguide 8 revolves while rotating by the rotational drive of the motor 18, and has the following configuration. Gear 70 rotating in conjunction with 1 st rotating shaft 69 of motor 18 performs gear transmission to gear 71 at a gear ratio of 1: 1, thereby rotating 2 nd rotating shaft 72 and rotating rotary waveguide 8 at the same rotational speed as motor 18. The gear 73 rotating in conjunction with the 1 st rotating shaft 69 is geared to the gear 75 at a gear ratio of 1: 10 by the gear 74, and the 2 nd rotating shaft 72 rotates around the 1 st rotating shaft 69 to revolve the rotary waveguide 8 at 1/10, which is the rotation speed of the motor 18. Thus, the rotary waveguide 8 rotates 10 times within the time of completing one revolution.

The cam 37 rotating in conjunction with the 1 st rotation shaft 69 is configured to press the switch 38 once per cycle in order to change the direction of the electromagnetic wave 42 and control the heating portion. The number of times the switch 38 is pressed and the position of the emission port 17 can be determined based on the driving time after the switch 38 is pressed, thereby controlling the emission direction of the electromagnetic wave. Of course, in the case of using a stepping motor for the motor 18, the positioning control can be performed accurately in accordance with the number of drive pulses after the switch 38 is pressed. Here, the direction of the electromagnetic wave is set or detected by the cam 37 and the switch 38.

The operation panel 64 includes a 1 st operation button 76 for setting the type of the food 6, the magnitude of the heating output, the heating time, the heating method, and the like by the user, and a 2 nd operation button for starting heating, that is, a start button 66.

The control means 19 starts the motor 18 based on the input of the 1 st operation button 76, controls the rotary waveguide 8 to a proper position based on the output of the switch 38, and then starts the emission of electromagnetic waves upon the magnetron pressing the start button 66. Then, when heating is performed, the electric motor 18 is driven or the emission direction of the electromagnetic wave from the emission port 17 is controlled to eliminate uneven heating or the output of the magnetron 2 is controlled to be changed to heat the food 6 until the heating is completed, as necessary, based on the input contents of the 1 st operation button 76 and the heating distribution information of the food 6 obtained by the temperature sensor 26.

In the present embodiment, the stage 20 on which the food 6 is placed also serves as a protective part for covering the rotary waveguide 8, and is configured by a spacer made of a low-loss dielectric material that does not easily absorb electromagnetic waves.

Fig. 38 is a cross-sectional view taken along line a-a' of fig. 37. On the bottom surface of the heating chamber 4, a notch 77 is provided in which the coupling portion 7 of the rotary waveguide 8 can move, and on the bottom surface of the waveguide 3, a notch 78 is provided in which the 2 nd rotary shaft 72 can move, and the rotation direction of the motor 18 is reversed on one side reaching end surfaces 79 and 80 of the notches. The time for this reversal may be determined by providing a stop or by the number of times the switch 38 is pressed.

Fig. 39 is a characteristic diagram showing how the movement of the rotating waveguide 8 in fig. 38 changes the direction of the electromagnetic wave 42 to be converted into the movement of the point (point)81 of the emission port 17. The bottom surface of the heating chamber 4 is represented by xy coordinates, and the center of the bottom surface of the heating chamber 4 is represented by coordinates (0, 0). For example, if the distance between the 1 st and 2 nd rotation axes 69 and 72, that is, the revolution radius of the rotary waveguide 8 is 70 mm, the distance from the center of the 2 nd rotation axis 72 to the measurement point 81, that is, the rotation radius is 60 mm, and the rotation period is 1/10 which is the revolution period, and the revolution angle is q, the coordinates of the measurement point are expressed by the expressions (2) and (3), and the spiral motion (cycloid) shown in fig. 39 is displayed.

x＝70cosθ+60cos(10θ)……(2)

y＝70sinθ+60sin(10θ)……(3)

As previously mentioned, the motor 18 is intended to be reversed to one of the end faces 79, 80, but is not shown here in a pictorial view.

FIGS. 40 to 42 show a 10 th embodiment and a modification of the 9 th embodiment.

This is a rotary waveguide having a two-stage structure, and the rotation ratio is set by the gear ratio of the gear so that the rotary waveguide rotates while revolving.

The structure will be described below with reference to fig. 40 and fig. 41, which is a main structural view thereof.

The gear 82 rotates (rotates) the gear 83 by the rotation of the motor 18 via the 1 st rotation shaft driving gear 82. Here, the gear 84 is integrally formed with the gear 83, and operates exactly in the same manner as the gear 83. When the gear 84 rotates around the 2 nd rotation shaft 72 together with the gear 83, the gear 84, the gear 83, and the 2 nd rotation shaft 72 rotate (revolve) around the gear 82 due to the action of the gear 85.

Here, a coupling portion 87 of the 1 st rotary waveguide 86 is provided around the 1 st rotation shaft 69, and a coupling portion 89 of the 2 nd rotary waveguide 88 is provided inside the 2 nd rotation shaft 72. Thus, the electromagnetic wave output from the magnetron 2 is transmitted through the waveguide 3, the coupling portion 87, the 1 st rotary waveguide 86, the coupling portion 89, and the 2 nd rotary waveguide 88 in this order. The advantage of this embodiment is that the distance from the magnetron 2 to the joint 87 and the distance from the joint 87 to the joint 89 are both independent of the rotation and always remain constant.

Therefore, the distance that the electromagnetic wave passes through is constant, matching is easy, and heating efficiency is high.

In the present embodiment, a stopper 90 is provided for positioning the waveguide, and the stopper 90 abuts against the gear 84 to determine a reference position.

In the case of using a stepping motor, in order to drive to the target position, it is simple to re-drive after reaching the reference position.

In summary, a sufficient number of pulses are input to drive to the reference position, and then only the number of pulses desired to be driven is input.

1/6, which has a rotation cycle defined as a revolution cycle, can move along the locus shown in FIG. 42 according to the gear ratios.

Fig. 43 and 44 are sectional views of essential parts of a high-frequency electric wave heating apparatus according to embodiment 11 of the present invention. The waveguide 3 has, in a lower portion thereof: a motor 18 having a rotation shaft 91 as a driving portion, a support portion 92, a drive shaft 93, and a mounting member 94. When the rotary shaft 91 rotates, a drive shaft 93 having a rectangular opening vertically fitted to the rotary shaft 91 having a rectangular cross section rotates. At this time, since the drive shaft 93 has the male screw 95 on the outside and the support 92 has the female screw 96 on the inside, it can be raised and lowered in accordance with the change of the rotation direction of the motor. The direction of the electromagnetic wave 42 emitted from the emission port 17 of the rotary waveguide 8 is not only changed in the circumferential direction control direction due to the rotation, but also can control the change of direction in the up-down motion. Fig. 43 shows the ascending state, and fig. 44 shows the descending state.

Here, a combination of rotation and up-and-down movement is shown, but of course, a combination with a turntable or a spiral motion as shown in the above-described embodiments is also possible. Various configurations, two-dimensional or even three-dimensional control are also contemplated.

Next, a 12 th embodiment of the present invention will be described with reference to fig. 45 to 46. FIG. 45 is a sectional view showing the structure of a high-frequency electric wave heating apparatus. And fig. 46 is an enlarged view of a key part of the embodiment.

Embodiment 12 is a structure in which an opening position changing means is provided as a local heating means without using a turntable. In fig. 45, the electromagnetic wave emitted from the magnetron heats the food 6 placed on the plate 21 in the heating chamber 4 through the waveguide 3. An opening for guiding the electromagnetic wave by connecting the waveguide 3 and the heating chamber 4 is defined by the 1 st shielding plate 97 and the 2 nd shielding plate 98. The 1 st shielding plate 97 has a notch 99, the 2 nd shielding plate 98 has a notch 100, and the combination of the notches 99 and 100 constitutes an opening position.

The 1 st shield plate 97 rotates around the shaft 102 due to the rotation of the 1 st stepping motor 101 as the opening position changing means. The 1 st stepping motor 101 rotates the 1 st rotation shaft 103, and the 1 st gear 104 is attached to the 1 st rotation shaft 103, and the 1 st gear 104 also rotates. Gears are formed around the 1 st shielding plate 97, and rotate according to the rotation of the 1 st gear. The 2 nd stepping motor 105 rotates the 2 nd rotation shaft 106, and the 2 nd gear 107 is attached to the 2 nd rotation shaft 106, and the 2 nd gear 107 also rotates. Gears are also formed around the 2 nd shield plate 98, and rotate in accordance with the rotation of the 2 nd gear 107.

Fig. 46 is an enlarged view of the shielding plate, fig. 46(a) is a 1 st shielding plate 97, and fig. 46(b) is a 2 nd shielding plate 98. As shown in fig. 46, in any of the shielding plates, a notch 99 is formed in the radial direction of the 1 st shielding plate 97, and a spiral notch 100 is formed in the 2 nd shielding plate 98 from the center toward the periphery. The two shield plates are vertically arranged and combined to form an opening at an arbitrary position of the circular shield plate. That is, any position of almost all regions in the heating chamber 4 can be used as an opening portion as a radiation position of the electromagnetic wave to perform local heating. The two shielding plates 97 and 98 may be rotated while changing their cycles, and the opening positions may be sequentially moved in the heating chamber 4, thereby uniformly heating the entire food.

The control means 19 drives the two shielding plates 97 and 98 at different periods in the initial stage of starting heating to perform uniform heating control, finds out the low temperature portion in the food 6 based on the temperature distribution detected by the temperature sensor 26, and controls the angles of the two shielding plates 97 and 98 so that the opening portion is positioned below the low temperature portion to perform local heating control. Such control is repeated to eliminate the low temperature portion of the food 6 and to heat the whole food to a uniform temperature.

In the present embodiment, two motors are used to drive two shield plates, but one motor may be used to change the ratio of gears, in which case the drive unit is reduced and reliability is improved. Further, the shielding plate may be linearly moved without being rotated, and the same effect can be obtained by providing a plurality of openings and providing the shielding plates separately.

In the above-described embodiments 1 to 12, the emission port or the opening portion of the electromagnetic wave emission position as the local heating means is provided on the bottom surface of the heating chamber 4, and this has an effect of emitting the electromagnetic wave to the heating chamber from a position as close as possible to the food in order to concentrate the electromagnetic wave on a part of the food to perform local heating. However, the provision of the emission port and the opening portion in the bottom surface of the heating chamber 4 is not a limitation of the present invention, and may be provided in the top surface and the side surface. In the case of being provided on the top surface, the food is moved in the height direction or the top surface is moved in the height direction, and the control effect is great in the state where the food is brought close to the top surface. In the case of the side surface, the food may be moved in the direction of the side surface having the rotary waveguide or moved in the direction of the food to bring the food close to one side surface having the rotary waveguide, or the food having a large height may be locally heated and controlled in the height direction. The distribution can be variably controlled by providing the emitting openings and the openings on two surfaces, or three or more surfaces, such as the bottom surface and the top surface, the bottom surface and the side surface, and this is effective particularly in the case of large food.

As a result, in order to perform local heating, the emitting port should be driven in a state where the opening portion is close to the food.

In the above-described embodiments 1 to 12, if one infrared detection element is driven as the temperature distribution detection means to detect a two-dimensional temperature distribution, there is an effect that the output of the infrared detection element can be easily adjusted at low cost. However, the use of one infrared detection element is not a limitation of the present invention, and for example, a plurality of infrared detection elements may be two-dimensionally arranged to detect a temperature distribution. In this case, the driving unit is omitted, and the reliability is improved, and the temperature distribution can be detected instantaneously. For example, the same effect can be obtained by linearly arranging a plurality of infrared detection elements to detect a temperature distribution on a straight line, detecting a two-dimensional temperature distribution by combining the rotation of a turntable, or driving and oscillating the linearly arranged infrared detection elements to detect a two-dimensional temperature distribution.

Further, although the magnetron and the emitting portion are led out from one waveguide, if a switchable structure in which a plurality of branches are provided with the emitting portion, respectively, is adopted, it is possible to achieve a more detailed local heating effect.

Instead of the waveguide, a coaxial line may be used.

Instead of the magnetron, a semiconductor oscillation element may be used.

Next, a 13 th embodiment of the present invention will be described with reference to fig. 47 to 51. Fig. 47 is a sectional view showing the structure of a high-frequency electric wave heating apparatus according to embodiment 13 of the present invention. Fig. 48 is a diagram showing the detection characteristics of the physical quantity detection means of the embodiment. Fig. 49 is a sectional view of a main part of the physical quantity detecting means of the embodiment. Fig. 50 is a block diagram illustrating a control operation of the embodiment. Fig. 51 is a characteristic diagram showing the temperature change characteristic of this example.

The turntable 1 is rotated at a constant cycle by a motor 22 as a rotating means. The rotation center of the motor 22 is located at approximately the center of the bottom surface of the heating chamber 4, while the rotation center of the motor 18 is located at a position offset from the center of the bottom surface of the heating chamber 4 and approximately in the middle of the center and the peripheral portion of the bottom surface. By this positional relationship, the heating portion in the radial direction of the turntable 1 can be changed by the rotary waveguide 8, and any position on the plate 21 can be heated in accordance with the rotation of the turntable 1.

An opening 29 is provided in the top surface of the heating chamber to secure the optical path of the temperature sensor 26, and a choke structure 108 for preventing electromagnetic waves from leaking to the outside of the heating chamber is formed in the vicinity of the opening 29.

The temperature sensor 26 is explained below. FIG. 48 shows a cross section B-B' of FIG. 47. An opening 29 is provided in the top 109 of the heating chamber and the choke structure is formed by two metal plates 110a and 110 b. 110a is a cylindrical metal member having a large size on the side of the top surface 109 and is tightly joined to the top surface 109, for forming an optical path. 110b are box-shaped metal members having small holes, which are tightly engaged with the top surface 109. The choke structures 110a and 110b allow infrared rays from inside the heating chamber 4 to pass through the small holes 111 to the outside, while electromagnetic waves inside the heating chamber 4 are shielded and hardly leak. In fig. 48, the dimension L is designed to be λ/4, that is, about 30 mm at a frequency of 2.45GHz, and the impedance of the aperture 111 is infinite, so that the shielding effect on the electromagnetic wave is maximized.

In fig. 48, 112, the amount of infrared rays inputted from the pyroelectric infrared detection element, that is, the amount of infrared rays relating to the temperature of the position in the heating chamber 4 as the field of view is outputted. The infrared detection element 112 is fixed inside the fixing member 113, and the lens 114 attached to the fixing member 113 reduces the field of view to detect the temperature in a narrow range. The lens 114 is a fresnel lens and is made of a material that transmits infrared rays. Reference numeral 115 denotes a stepping motor, and the pinion 117 and a chopper (chopper) are driven to rotate by a reference numeral 116 as a 1 st rotation axis.

The shutter (chopper)118 forms a slit and rotates while opening and closing an optical path to the infrared detection element 112. The pinion 117 is in driving engagement with a large gear 119, a 2 nd rotating shaft 120 is attached to the large gear 119, and the 2 nd rotating shaft is rotatably attached via a support portion 121. A printed circuit board 122 is mounted on the 2 nd rotation shaft 120, and an electronic circuit (not shown) such as an amplifier circuit is mounted on the printed circuit board 122 in addition to the infrared detection element 112. These are housed in a metal case 124 having a small hole 123 at a position in the infrared light path, covered with a metal cover 125, and fixed to the choke structure 110 with the metal cover 125.

The stepping motor 115 swings the infrared detection element 112 from near to front to far in fig. 48 in this configuration, and the shutter 118 opens and closes the optical path. The oscillation cycle of the infrared detection element 112 is set to be an integral fraction of the rotation cycle of the motor 22, that is, the rotation cycle of the motor 22 is an integral multiple of the rotation cycle of the infrared detection element 112, and the temperature at the same position can be detected for every rotation of the motor 22.

Fig. 49 shows the detection position of the infrared detection element 112. The detection field of view of the infrared detection element 112 is indicated by a small circle, and the locus of the detection center is indicated by a dotted line. In this example, the temperature detection position 5 is changed unilaterally with the shaking head of the infrared detection element 112. After the oscillating motion and the rotation of the motor 22 are combined, the detection position covers the entire dish 21, and two-dimensional temperature distribution detection can be performed. Since the motor rotates at a cycle that is an integral multiple of the oscillation frequency of the infrared detection element 112, a temperature difference from before the turret rotates once and a temperature change from the start can be detected at each detection position.

Next, the control operation of the control means 19 will be described with reference to fig. 50. The control means 19 controls the motor 18 based on the temperature detected by the temperature distribution detecting means 26, and it is the object discrimination means 126 for discriminating, at each detection position, whether the temperature detected first is the temperature of the food 6 or the temperature of the plate 21 or the wall surface of the heating chamber 4. At the initial stage of heating, it is not known how large the food 6 is, at what position, etc., and therefore, the motor 18 is first controlled by the uniform heating means 127. The uniform heating means 127 rotates the electromagnetic wave in a sufficiently faster period than the rotation period of the motor 22, reciprocates the electromagnetic wave in a half rotation, or performs random driving, etc., and agitates the electromagnetic wave in the heating chamber 4 to uniformly distribute the electromagnetic wave. When the motor 18 is controlled by the uniform heating control means 127, whether or not the food 6 is present is discriminated on the basis of the temperature rise at each detection position.

FIG. 51 shows the surface temperature change of the food 6 and the temperature change of the non-food 6 portion such as the dish 21 when the driving of the motor 18 is controlled by the uniform heating control means 127. The horizontal axis represents the elapsed time from the start of heating, the vertical axis represents the temperature change from the start of heating, the hatched region C represents the temperature change of the non-food 6 portion such as the tray 21, and the hatched region D represents the temperature change of the food 6. Since the plate 21 has a smaller dielectric loss than the food 6, it is difficult to absorb electromagnetic waves and the temperature hardly rises, so that it can be clearly distinguished. The temperature change calculation means 128 stores in advance the temperatures corresponding to the respective detection positions from the 1 st week of heating of the motor 22, for example, and calculates the temperature difference Δ T from the temperature corresponding to the respective detection positions after the time T13 has elapsed. The temperature change comparing means 129 distinguishes that the food 6 is the food 6 when the temperature difference Δ T as the calculation result of the temperature change calculating means 128 is larger than the predetermined value Δ T1, and distinguishes that the dish 21 is the dish 21 when the temperature difference Δ T is smaller than Δ T1.

If the heated object discriminating means 126 can discriminate whether the object at each detection position is the food 6 or the dish 21, the control of the motor 18 can be switched from the uniform heating control means 127 to the local heating control means 131 by the heating mode switching means 130. The local heating control means 131 is used to control the electromagnetic wave concentration position while stopping the motor 18 at an appropriate position. Reference numeral 132 denotes a low temperature portion discrimination means, and the heated object discrimination means 126 discriminates a low temperature portion from the food 6 and the determined detection position. The local heating control means 131 controls the driving of the motor 18 so as to emit electromagnetic waves to the low temperature portion determined by the low temperature portion determination means 132. On the other hand, if the local heating control means 131 controls the electromagnetic wave to be emitted to the low temperature portion of the food 6 to eliminate the low temperature portion of the food 6 and make the whole temperature uniform, the uniform heating control means 127 may be used again to control the motor 18.

The low temperature portion discriminating means 132 stores, as the heating position, the detection position at which the object discriminating means 126 has discriminated that the detection temperature is the lowest among the detection positions of the food 6 in the one-motion oscillating reciprocating motion of the infrared ray detecting element 112. The infrared detection element 112 repeatedly swings the head during one rotation of the motor 22, and the heating positions that reciprocate one at a time are stored. By the rotation of the motor 22, the local heating control means 131 adjusts the angle of the motor 18 toward the stored heating position located in the radial direction above the rotary waveguide (emitting portion) 8, and heats the heating position, that is, the low temperature portion of the food 6. This control is repeated to eliminate the low-temperature portion of the food 6, and the whole food is uniformly heated.

In a simple method for reducing the number of times of driving the motor 18, the detection positions of the infrared detection elements 112 may be arranged on concentric circles, whether the food 6 or the dish 21 is determined on a circumferential basis of each concentric circle, the highest temperature in the circumference where the food can be determined is determined, the lowest circumference where the highest temperature is determined by the low temperature portion determination means 132, and the angle of the motor 18 is adjusted so that the electromagnetic waves are concentrated on the circumference. In this case, the durability of the motor 18 is improved.

The term "uniform" in the uniform heating control means 127 means a meaning expressing a wide-range heating with respect to local heating, and does not mean a meaning conditioned on completely uniform general heating.

The physical quantity detecting means is described as the temperature distribution detecting means in the above-described embodiment 13, but the present invention is not limited thereto. For example, it is also possible to use a solid-state image pickup element called a CCD image sensor that can recognize the shape and color of the food 6. In this case, the control means may control the local heating means according to the color and distribution thereof which change with heating, and for example, in the case where the object to be cooked is meat, the control means may control the local heating means according to the color of the meat from red to white until all the meat turns to light coffee. The control means can also control the local heating means according to the change of the shape, for example, the local heating means is controlled to heat the whole cake because of the change of softness and expansion in the cake making process. The same effect can be obtained by using a plurality of light emitting elements and light receiving elements and recognizing the shape based on the pattern of the light path interruption. Further, if the control pattern of the local heating means is stored in advance in accordance with the shape, the control means can control the local heating means based on the initial shape recognition that the solid-state imaging element, the plurality of light-emitting elements, and the light-receiving element can recognize. Further, if a menu and a control pattern of an optimum local heating means are stored in advance in association with the weight, it is also possible to use a weight sensor as the physical quantity detection means.

In the above description of embodiment 13, the control means is described as a configuration having the uniform heating control means, the local heating control means, and the heating pattern switching means, but the present invention is not limited to this. For example, the case where the uniform heating control means and the heating mode switching means are not provided will be described with reference to fig. 52. Fig. 52 is a block diagram illustrating a heating operation of the high-frequency electric wave heating apparatus. In this case, the means for discriminating the object to be heated at the initial stage of the start of heating distinguishes the food 6 from the plate 21. The temperature change comparing means 129 compares the temperature with a predetermined temperature change determined by the heating elapsed time at every moment, and determines that the temperature change is larger than the predetermined temperature change as the food 6 and smaller as the dish 21. The predetermined temperature change is a function determined by the heating elapsed time, and is indicated by a straight line E in fig. 51. Although a small temperature change of the food 6 at the beginning of heating causes an error in discrimination between the food 6 and the dish 21, the error is corrected as the heating progresses, and therefore, the overall heat distribution is not greatly affected.

Further, there is a method of fixing the motor 18 at a predetermined position in the initial stage of the start of heating. Since the food 6 is usually placed in the center of the heating chamber 4, and the periphery thereof is likely to be heated, and the center portion thereof is not likely to be heated, the food is heated after fixing the direction of the rotary waveguide (emitting portion) 8 as shown in fig. 12 and 25. This method may also miss the optimal heating position early on, but is corrected as the heating progresses, with no large effect on the overall heating profile. Further, the initial fixed position is not provided at the center but provided at the periphery shown in fig. 13 and 26 and other positions, and appropriate heating position control is obtained as heating progresses, and therefore the same effect is obtained.

The 14 th embodiment of the present invention will be explained with reference to fig. 53. Fig. 53 is a block diagram illustrating a control operation of the high-frequency electric wave heating apparatus according to embodiment 14 of the present invention. Further, the same members as those of the embodiment 13 are denoted by the same reference numerals. Reference numeral 133 denotes a menu setting means for setting a cooking menu by a user. The menu setting means 133 includes buttons corresponding to cooking, for example, a heating button 133a, a raw food defrosting button 133b, a milk button 133c, and the like, and the user sets a cooking menu by pressing a certain button. Reference numeral 134 denotes a control mode selection means for selecting a mode according to the cooking menu set by the menu setting means 133, and selecting whether to control the motor 18 by the heating mode switching control means 135 or the heating mode non-switching control means 136. The control operation of the heating mode switching control means 134 is the same as that of the above-described embodiment 13. That is, the motor 18 is controlled by the uniform heating control means 127 at the beginning of the heating start, and the motor 18 is controlled by the local heating control means 131 based on the low temperature portion detected by the low temperature portion determination means 132 after the food 6 and the dish 21 are distinguished by the object to be heated determination means 126. On the other hand, the heating mode non-switching control means 136 controls the motor 18 only by using the local heating control means 131 from the initial stage of heating.

Reheating of cold rice, reheating of cooked or roasted food, and the like are performed while focusing on local heating, and it is sufficient to control the local position to be changed so that a uniform temperature distribution is obtained as a whole. The same applies to the thawing of meat and fish. However, the liquid such as milk is heated intensively at the bottom of the container to generate convection, and the liquid can be heated uniformly in the height direction. Therefore, in general, as shown in fig. 12 and 25, for a food placed in the center of the heating chamber, the motor 18 fixes the position of the rotary waveguide 8 as the emitting portion so that the center portion is locally heated. When the milk container is not placed at the center, the position of the milk container is detected by the heated object discrimination means 34, and the motor 18 may be fixed by setting the position of the rotary waveguide 8 as the emitting unit so that the milk container position passes through the position of the rotary waveguide 8 as the emitting unit. In the case of placing a plurality of food items, if the food items are placed on concentric circles, the position of the concentric circle may be locally heated by fixing the position of the rotary waveguide 8 as the emitting portion by the motor 18. In the case where a plurality of food items are not placed on a concentric circle, the motor 18 may change the direction of the rotary waveguide 8 as the emitting portion each time according to the position of the milk container passing through the vicinity of the rotary waveguide 8 as the emitting portion.

The control action is first that the user presses the button of the setup menu. If the pressed button is the heating button 133a or the defrosting button 133b, the control mode selection means 134 selects the heating mode switching control means 135, starts the heating initial uniform heating control means 127 to control the motor 18, and thereafter the local heating control means 131 controls the motor 18. If the button pressed by the user is a milk button, the control mode selection means 134 selects the heating mode non-switching control means 136. In this case, the local heating control means 131 first controls the motor 18 to fix the position of the rotary waveguide 8 as the emitting portion so that the center of the heating chamber 4 is locally heated. If the heated object discrimination means 126 can determine that the position of the milk container is at the center, that is, the milk container is still heated locally at the center, and if it is determined that the position of the milk container is not at the center or that there are a plurality of milk containers, the motor 18 may be controlled and the position of the emitting portion 8 may be set to heat locally at the center of the detected position of the milk container.

In the case where the milk container is not located at the center, the magnetron may be stopped from radiating during the time when the turntable is rotated to a position away from the emitter 8, so that the electromagnetic wave does not enter the heating chamber 4. In this case, the heating takes time, but the temperature distribution may be better, and there is an effect that energy is not wasted. In addition, hot wine, miso soup, coffee, etc. are also the same as milk, and the same effect can be obtained by adding these contents as a menu to the menu setting means 133 set by the user.

Next, a 15 th embodiment of the present invention will be described with reference to fig. 54 and 55. Fig. 54 is a sectional view showing the structure of a high-frequency electric wave heating apparatus according to embodiment 15 of the present invention. FIG. 55 is a sectional view of a main part of the temperature distribution detecting means of the same embodiment. The same components as those in the above embodiments are denoted by the same reference numerals, and descriptions thereof are omitted.

Embodiment 15 is a structure not using a turntable motor as a rotating means. The electromagnetic wave output from the magnetron 2 is incident into the heating chamber 4 through the waveguide 3 and the feeding chamber 15, and heats the food 6 in the heating chamber 4. A rotary waveguide 8 as a radiating portion is provided in the feeding chamber 15, and the rotary waveguide 8 is rotated by a motor 18 as a waveguide moving means. And 25 is a cover covering the feeding chamber 15. The motor 18 is a stepping motor, and rotationally drives the 1 st rotation shaft 137. A large gear 138 is mounted on the 1 st rotating shaft 137. Reference numeral 139 denotes a ring gear, a groove formed on the inner side of the gear teeth and serving as a bearing of the pinion gear 140, and is fixed to the waveguide 3. The pinion gear 140 is in a gear transmission relationship with the large gear 138 and the ring gear 139, the 2 nd rotation shaft 141 is attached to the pinion gear 140, and the 2 nd rotation shaft 141 is rotatably attached with a groove provided in the rotation gear 139 as a bearing. The 2 nd rotation shaft 141 is attached with a rotation waveguide 8. When the motor 18 is rotated in this configuration, the 2 nd rotation shaft 141 moves around the large gear 138 along the ring gear 139 while repeating rotation. The motor 18 performs the adjustment of the initial position using either the origin detection switch or the stopper, and thereafter gradually accumulates the moving angle from the initial position so that the rotation angle can be known frequently to know both the position and the direction of the rotary waveguide 8.

FIG. 55 is a sectional view of a main part of the temperature distribution detecting means, and shows a section F-F' of FIG. 54. Reference numeral 115 denotes a stepping motor, which swings the infrared detection element from the near side to the deep side of the drawing of fig. 55, and controls the opening and closing of the optical path by the shutter 118. Reference numeral 142 denotes a driving means for driving the entire metal case 124 including the infrared detection element 112, and is constituted by a stepping motor. The stepping motor 142 rotates the rotary shaft 143, and drives the connecting portion 144 attached to the rotary shaft to oscillate the infrared detection element 112 in the left-right direction of fig. 55. Here, the swing period of the stepping motor 142 is driven at a period of an integral multiple which is much slower than the swing period of the stepping motor 115, and the temperature of the same position can be detected every time the stepping motor 142 swings. With this configuration, the temperature of all the regions of the heating chamber 4 can be detected, and a two-dimensional temperature distribution can be detected. Further, since the temperature at the same position can be detected every reciprocation when the stepping motor 142 oscillates the head, the temperature difference from the temperature before one reciprocation and the temperature change from the initial stage can be calculated for each detected position.

The control means 19 rotates the motor 18 at a constant period to perform uniform heating control, and if a food is discriminated, a low temperature portion is found in the discriminated food, and the angle of the motor 18 is controlled so that the rotary waveguide 8 faces the position of the low temperature portion. By repeating this operation, the low-temperature portion of the food 6 can be eliminated, and the whole food can be uniformly heated. In the case of this embodiment, since the food 6 does not rotate, the heavy food can be heated, and the space in the heating chamber 4 can be effectively used. In the above embodiment, the position and direction of the rotary waveguide 8 are controlled by one motor, but this is not a limitation of the present invention, and the direction and position of the rotary waveguide 8 may be controlled by another motor or may be controlled by linear two-axis movement. These methods have a more careful local heating effect.

The following describes the 16 th embodiment of the present invention with reference to FIGS. 56 to 57. Fig. 56 is a sectional view showing the structure of a high-frequency electric wave heating apparatus according to embodiment 16 of the present invention. And FIG. 57 is a sectional view of a main portion of the electromagnetic wave emitting portion of this embodiment. The same components as those in the embodiments 13 to 15 are denoted by the same reference numerals, and the description thereof will be omitted.

Embodiment 16 provides the opening position changing means as the distribution changing means. In fig. 56, the electromagnetic wave emitted from the magnetron 2 heats the food 6 placed on the plate 21 of the heating chamber 4 through the waveguide 3. The opening for connecting waveguide 3 and heating chamber 4 to guide electromagnetic waves is configured such that 1 st opening 145 is located near the center of heating chamber 4, and 2 nd opening 146 is located near the periphery of heating chamber 4 and arranged in the radial direction of rotation of turntable 1. Reference numeral 147 denotes a shield plate, which shields one of the opening 145 and the opening 146, and is configured as a semicircular metal plate and driven by a rotating shaft 148 made of a low loss material that does not easily absorb electromagnetic waves. Reference numeral 18 denotes an opening position changing means, which is constituted by a stepping motor, and drives the rotation shaft 148 to rotate so that the shielding plate 147 shields one of the openings 145 and 146. By changing the position of the electromagnetic wave emitted to the heating chamber 4 in this way, the portion of the food 6 directly above the unshielded opening portion is locally heated in a concentrated manner. While it is also possible to achieve a uniform heating of the food product 6 if the shielding plate is rotated at certain periods.

FIG. 57 shows a section G-G' of FIG. 56. The openings 145 and 146 are rectangular and parallel to the bottom and four sides of the heating chamber 4 which is also rectangular. In fig. 57(a), as in fig. 56, since the 1 st opening 145 is shielded by the shielding plate 147 and the electromagnetic wave is incident on the heating chamber 4 through the 2 nd opening 146, the portion of the food 6 located in the vicinity of the periphery of the heating chamber 4 is locally heated. In contrast, in fig. 57(b), the shielding plate 147 shields the 2 nd opening 146 and the electromagnetic wave is radiated from the 1 st opening 145 into the heating chamber 4, so that the portion of the food 6 located near the center of the heating chamber 4 can be heated locally.

The control means 19 rotates the shielding plate 147 at a constant period in the initial stage to perform uniform heating control, and if the food 6 is discriminated based on the temperature distribution detected by the temperature sensor 26, the low temperature portion of the food 6 is found and stored as the heating position. The position of the shielding plate 147 is switched at every moment to perform optimum local heating in accordance with the rotation of the turntable 1 and the heating positions of the openings 145 and 146 in a certain radial direction, and the repeated operation disappears the low temperature portion of the food 6, thereby uniformly heating the whole food.

In the present embodiment, the simple and compact structure in which the semicircular metal plate is rotated by providing two openings has been described, but these are not limitations of the present invention, and a method of performing finer local heating control by using a plurality of openings may be adopted, or the shielding plate may be moved linearly instead of being rotated. Further, the same effect can be obtained by providing the shielding plates in the plurality of openings.

Next, a 17 th embodiment of the present invention will be described with reference to fig. 58 and 59. Fig. 58 is a block diagram illustrating a control operation. Fig. 59 is a temperature characteristic diagram particularly explaining the operation of the contour determination means. The same components as those in the embodiments 13 to 16 are denoted by the same reference numerals, and the description thereof will be omitted.

In fig. 58, the local heating means 16 is first controlled by the uniform heating control means 127 at the initial stage of heating. If the heated object discriminating means 126 can discriminate the presence or absence of food at each detection position detected by the temperature distribution detecting means 26, the heating pattern switching means 130 controls the local heating means 16 by the uniform heating control means 127, and switches to control the local heating means 16 by the local heating control means 131.

The heated object discrimination means 126 is composed of a temperature change calculation means 128 and a contour discrimination means 149. The temperature change calculating means 128 stores the temperature obtained by the temperature distribution detecting means 26 corresponding to each detection position at the initial stage of the start of heating, and calculates the difference between the temperature corresponding to each detection position and the initial temperature of the same detection position after a predetermined time has elapsed. The contour of the food is determined based on the temperature change Δ T from the initial stage corresponding to each detection position.

In fig. 59(a), the mesh is the detection position of the temperature distribution detection means 26, and the hatched portion is the food 6. The temperature distribution detecting means 26 detects the temperature distribution at the detection position in a matrix shape by a configuration such as two-dimensionally arranging a plurality of infrared detection elements or shaking the elements linearly arranged. In general, the temperature change of the food 6 from the initial stage of starting heating is larger than the temperature change of the place where the food is not present. The X-direction differentiating means 150 calculates the temperature difference between the adjacent detection positions in the X direction where the detection positions are arranged in a matrix, i.e., in the lateral direction in fig. 59. The detected position where the calculation result is larger than a predetermined value is stored. The detection position indicated by the diagonal lines in fig. 59(b) is a detection position larger than the predetermined value stored in the X-direction differentiating means 150. The Y-direction differentiating means 151 calculates the temperature difference between the adjacent detection positions in the Y direction where the detection positions are arranged in a matrix, i.e., in the vertical direction in fig. 59. The detection position where the calculation result is larger than a predetermined value is stored. The detection position indicated by the diagonal lines in fig. 59(c) is a detection position larger than the predetermined value stored in the Y-direction differentiating means 151.

The shaping means 152 calculates the logical sum of the detected position stored by the X-direction differentiating means 150 and the detected position stored by the Y-direction differentiating means 151. That is, the detected position stored in either the X-direction differentiating means 150 or the Y-direction differentiating means 151 is determined as the contour of the food. Since the temperature rise of the food is distributed, there is a position where the temperature difference from the adjacent detection position is large even in the interior of the food, and the maximum periphery of the shaping means 152 is defined as the outline of the food. Further, even if a part of the surrounding contour is interrupted, the contour is connected. The heated object discrimination means 126 discriminates the contour of the food as described above, and the inner side surrounded by the contour is defined as the food.

The low temperature portion discriminating means 132 discriminates the low temperature portion from the food discriminated by the heated object discriminating means 126, and the local heating control means 131 controls the local heating means to emit the electromagnetic wave to the low temperature portion discriminated by the low temperature portion discriminating means 132. Since it is thus determined that the object is emitting electromagnetic waves, the heating efficiency can be improved without wasting energy.

An 18 th embodiment of the present invention will be described with reference to fig. 60. Fig. 60 is a block diagram illustrating a control operation of the high-frequency electric wave heating apparatus according to the present invention. The same components as those in the above-described 13 th to 17 th embodiments are denoted by the same reference numerals, and descriptions thereof are omitted.

The 18 th embodiment is a case where only a part of food is intended to be heated, for example, a case of heating a lunch box of a grand assy, food which should be heated such as rice and food which should be cold-eaten such as raw fish fillet, pickles are put in a container. In this case, the rice, the sliced raw fish, and the pickles may be placed in the container and placed in the heating chamber to heat the rice without separating the rice from the sliced raw fish and the pickles, and this will be described as an example. In fig. 60, reference numeral 153 denotes a heating range setting means for setting a heating range by a user. The heating range setting means 153 is constituted by a setting screen 154 made of liquid crystal, a cross cursor (cursor) button 155, a setting button 156, and a cancel button 157.

The setting screen 154 is used by the user to set which range of the bottom surface of the heating chamber is to be heated. The user first presses the set button 156 to start setting. At this time, the 1 st point 158 is displayed in the upper left corner of the setting screen 154. At this time, the user operates the cursor button 155 to move the 1 st point 158 on the setting screen 154. The cursor button 155 is composed of an up button 155a, a down button 155b, a left button 155c, and a right button 155d, and the 1 st point 158 can be moved to any position in any direction of up, down, left, and right by operating these buttons. The user moves point 1158 to the end of the heating range and presses the set button 156. The position of point 1158 is now fixed and point 2 159 is shown in the same position. The user similarly operates the cursor button 155 to move the 2 nd point 159. At this time, a rectangle 160 having a 1 st dot 158 and a 2 nd dot 159 as diagonal lines is displayed on the setting screen 154. The range indicated by the rectangle is the heating range. The user moves the 2 nd dot 159 to an arbitrary position on the setting screen 154 to set the heating range in the rectangle 160. The set button 156 is pressed again to determine the 2 nd point 159 and the rectangle 160. If the user presses the setting button 156 again in the case where there are a plurality of heating ranges, the 1 st point 158 is displayed on the setting screen 154 again, and the above-described operation is repeated thereafter. Pressing the cancel button 157 in the event of an operation error can cancel the contents of the setting just pressed on the setting button 156.

If the user operates the heating range as described above, the control means 19 can control the heating range to perform uniform heating. The low temperature portion discriminating means 132 discriminates the low temperature portion from the heating range set by the heating range setting means 153 based on the output signal of the temperature distribution detecting means 26. The local heating control means 131 controls the local heating means 16 to emit electromagnetic waves to the low temperature portion determined by the low temperature portion determination means 132. Therefore, the low temperature portion disappears from the heating range, and the entire heating range can be uniformly heated. Furthermore, the food to be eaten cold can be kept in a low-temperature cooking state without heating the place outside the heating range.

Although the present embodiment describes the case where different foods such as boxed lunch of a great sumptuous fighter are put into the heating chamber at the same time, the control means is simple in structure because it is not necessary to discriminate the food at the initial stage of heating as long as the heating range is set as described above even when a single food is heated. The heating range setting means 153 is constituted by the setting screen 154, the cursor button 155, the setting button 156, and the cancel button 157, but the present invention is not limited to these, and for example, a method using a touch panel or a mouse may be used, and the same effects are obtained. The operation is simplified by setting the heating range in a rectangular shape, but the same effect is obtained by setting a freely selected curve. In addition, if a commodity such as a lunch box of a very popular knight is used, or if a symbol such as a bar code is printed on a packaging bag of the commodity to obtain a heating range, the symbol can be optically read to set the heating range.

Next, a 19 th embodiment of the present invention will be described with reference to fig. 61. Fig. 61 is a block diagram illustrating a control operation of the high-frequency electric wave heating apparatus according to the present invention. The same components as those in the above-described embodiments 13 to 18 are denoted by the same reference numerals for convenience, and descriptions thereof are omitted.

The 19 th embodiment is similar to the 18 th embodiment in that only a part of food is heated, and a case of providing a customer service by heating a box lunch in a shop will be described below. Generally, the kinds of goods for such business are limited, and if the same kind of goods is placed in the same position in the container, the food is placed in the same position. The kinds of the commercial products include, for example, a rice box, a roast rice box, and a salmon box of the sumptus, and in the case of the roast rice box, the positions of the rice and the roast are determined. Thus, the same kind of goods is reheated due to the limited kind. In this case, for example, if the heating ranges of the products are registered in advance in association with the codes, using "1" as a lunch box for a very popular fighter, "2" as a barbecue box and "3" as a salmon box, the heating range of the product selected by the customer can be called up based on the codes, and the operation of setting the heating range can be simplified.

In fig. 61, the heating range setting means 153 includes a number button group 161 from "1" to "10", a registration button 162 as registration means, and a call-out button 163 as registration call-out means. When registering the heating range, the heating range is first set by the cursor button 155 and the setting button 156 in the operation method described in the above-described embodiment 18. Next, the registration button 162 is pressed, and a number button in the number button group 161 is pressed. Then, upon pressing the set button 156, the registration storage means 164 stores the heating range together with the pressed numeric button code. In calling up the heating range, the call-up button 163 is pressed first, and then the numeric button corresponding to the product in the numeric button group 161 is pressed. The stored heating range is displayed on the setting screen 154 in accordance with the number pressed by the registration storage means 164. If no error is considered, the setting button 156 is pressed to indicate confirmation. Once registered, the operation thereafter is simply called out and the heating range can be simply set.

Once heating is started, the control means 19 controls the local heating means 16 to heat the heating range to a uniform temperature, as in the above-described embodiment 18. That is, the low temperature portion discriminating means 132 discriminates the low temperature portion from the heating range set by the heating range setting means 153 based on the signal output from the temperature distribution detecting means 26, and the local heating control means 131 controls the local heating means 16 to emit the electromagnetic wave to the low temperature portion discriminated by the low temperature portion discriminating means 132.

In the present embodiment, the number button group 161, the registration button 162, and the call-out button 163 are used to describe the registration means and the registration call-out means, but the present invention is not limited to this, and for example, a code of an operation program, a number, a letter, or the like may be displayed on the setting screen 154, and the cursor 155 and the setting button 156 may be used as the registration means and the registration call-out means. And the operation can be simplified by printing a code on the commodity packaging bag and optically reading the code without using the number button group.

Fig. 62 is a sectional view of a high-frequency electric wave heating apparatus according to embodiment 20 of the present invention. In the present embodiment, the electromagnetic wave emitted from the magnetron 2 is emitted from the waveguide 3 to the heating chamber 4 through the opening 165, and the turntable 1 on which the food 6 is placed makes a spiral motion, which is an application of embodiment 9 shown in fig. 37. Since the food 6 is positioned and driven by this structure and the direction in which electromagnetic waves are incident on the food 6 is changed according to the position thereof, the cam 37 and the switch 38 can be said to be a position detecting portion that detects the position of the food, which is a representative position switching method for switching the heating portion to heat, for example, the center of the food 6 or the periphery thereof.

Fig. 63 and 64 are sectional views of essential parts of a high-frequency electric wave heating apparatus according to embodiment 21 of the present invention. Unlike fig. 43 and 44, in this embodiment, the position of the food item 6 is subjected to positioning drive, and unlike fig. 62, three-dimensional control is performed not only by two-dimensional change due to rotation of the turntable 1 but also by change due to vertical movement. Fig. 63 shows the ascending state, and fig. 64 shows the descending state.

Here, for simplicity, a combination of rotation and vertical movement is shown as a representative example of the three-dimensional movement, but it is needless to say that a combination with a spiral movement is also possible, and various configurations are also conceivable.

And it is not necessary to limit the number of times of replacement of the heating distribution, and the replacement is always considered to prevent the occurrence of the unevenness of the heating distribution.

Fig. 65 is a main part configuration diagram of a high-frequency electric wave heating apparatus according to embodiment 22 of the present invention, and shows a configuration of the turn table 1 viewed from below. Unlike fig. 7, the turntable 1 is made of a material such as ceramic, which is less likely to absorb electromagnetic waves and has a good performance of transmitting electromagnetic waves, and includes a disc 166 and a rotary bearing 48. The electromagnetic wave easily passes through the gap even if the gap is not present.

In the case of a microwave oven with a grill in which electromagnetic waves enter from below, the turntable 1 serves as a passage for the electromagnetic waves, and the heating element 28 is used, the turntable 1 is designed to have a structure which has high heat resistance and is easily permeable to the electromagnetic waves, as shown in fig. 17 and 65.

Fig. 66 is a sectional view of a main part of a high-frequency electric wave heating apparatus according to embodiment 23 of the present invention, showing a dimensional relationship between the turntable 1 and a central portion 167 of the bottom surface of the heating chamber 4. When the radius of the turntable 1 is R (diameter 2R in fig. 66) and the radius of the protrusion of the central portion 167 of the bottom surface of the heating chamber 4 is R (diameter 2R in fig. 66), 2R > 2R, that is, R > R is given. Therefore, even if water or something is knocked over the turn table 1, water does not leak downward from the heating chamber along the axis of the turn table, and the water stays outside the protrusion 2R of the central portion 167 of the bottom surface of the heating chamber 4, so that the turn table can be cleaned without being detached. Particularly, when the turntable 1 is made of ceramics as shown in fig. 65, the ceramics are generally considered to have low strength, and it is necessary to take measures to prevent damage due to repeated operations such as removal and attachment from the rotating shaft, thereby improving the service life. Therefore, the structure of the embodiment does not need to be disassembled during cleaning, and the service life is prolonged.

Fig. 67 is a sectional view of a high-frequency electric wave heating apparatus according to embodiment 24 of the present invention.

The electromagnetic wave emitted from the magnetron 2 heats the food 6 on the turntable 1 in the heating chamber 4 through the waveguide 3. The electromagnetic wave output from the magnetron 2 is output from the 1 st waveguide 3A, branched to the waveguides 3B and 3C at the branch point 168, and enters the heating chamber 4 through the openings 169A and 169B in the bottom surface of the heating chamber. In this case, the adjacent portions of the walls of the waveguides 3B and 3C are formed by a common metal plate. And the branch point 168 is formed at a place (node) where the electric field in the 1 st waveguide 3A is weak. The 1 st waveguide 3A is projected against the wall surface 170 of the antenna 30 of the magnetron 2 to keep the distance between the antenna 30 and the wall surface 170, and the waveguides 3B and 3C do not have the projection of the antenna 30, so that the distance can be narrowed. Therefore, compared with the 1 st waveguide 3A, the cross-sectional areas of the waveguides 3B and 3C are made smaller, and thus a structure in which a large space is not occupied although a plurality of waveguides are overlapped can be obtained. In the present embodiment, the sectional area of the 1 st waveguide 3A is enlarged by the wall surface 170 in consideration of the waveguides 3B and 3C. Further, the matters that the lengths of the waveguides 3B, 3C are about integral multiples of 1/2 of the in-tube wavelength g from the branch point 168 to the terminal end, and the matters that the width of the branch point 168 is 1/4 of the in-tube wavelength g will be described in detail with reference to fig. 68.

The metallic shielding portion 171 is driven by the driving portion 172, and operates between the openings 169A and 169B when it comes into contact with the projections 173 on the heating chamber 4 and the waveguides 3B and 3C, so as to switch the openings 169A and 169B through which electromagnetic waves are easily transmitted. The sealing portion 174 prevents electromagnetic waves from leaking to the outside of the heating chamber 4 and the waveguide 3 regardless of the position of the shielding portion 171.

The control means 19 controls the emission of electromagnetic waves from the magnetron 2, the operation of the cooling fan 27 of the magnetron 2, the operation of the driving unit 172 of the shielding unit 171, the operation of the motor 22 for rotating the turntable 1, and the operation of the height driving unit 175 for changing the height of the turntable 1, based on detection signals from the temperature sensor 26 for detecting the temperature of the food 6, the weight sensor 23 connected to the turntable 1 for detecting the weight of the food 6, and the optical sensors 61 and 62 for detecting the shape of the food 6. Particularly, when the magnetron 2 does not emit the electromagnetic wave, the shield 171 is controlled to move, and when the heating is completed, the position of the shield 171 and the height of the turntable 1 are controlled, so that the light food 6 can be heated with a good distribution in structure and the heating efficiency can be improved. In any application, when the user puts food and starts heating, a detection unit (for example, a weight sensor) capable of making an error detection is provided in a state where the behavior of the electromagnetic wave immediately after the start of heating is unstable (so-called rising), and the output of the detection unit is controlled not to be received or ignored until the behavior becomes stable. Further, in the case of the food 6 (particularly, a large amount of food or the like), the position of the shielding portion 171 and the height of the turntable 1 are changed a plurality of times during heating, and the heating distribution and the heating efficiency are optimized.

Here, when the driving unit 172 drives and changes the position of the shielding unit 171, the opening from which the electromagnetic wave is easily emitted and the opening from which the electromagnetic wave is not easily emitted can be switched among the plurality of openings 169A and 169B, and the electric field distribution in the heating chamber 4 can be switched. In particular, since the position of the shielding portion 171 can be freely set in accordance with the signal from each detection portion, the electric field distribution state suitable for the heating purpose can be selected. In order to accurately determine the position of the shielding portion 171, the reference point is set at a certain position (not shown in fig. 67), and the position of the shielding portion 171 can be easily managed in accordance with the distance moved from the reference point.

Since the height h of the turntable 1 is changed by the height driver 175, the height of the food 6 is changed, and the heating distribution of the food 6 is changed even with the same electric field distribution. Similarly, if the height of the turntable 6 is adjusted to the optimum height h according to the difference between the signal from each detection unit and the electric field distribution due to the change in the position of the shielding unit 171, a heating distribution more suitable for the heating purpose can be achieved. Similarly to the shielding part 171, the height h of the turntable 1 may be accurately determined by managing the reference point and the movement distance (not shown in fig. 67).

The turntable 1 is usually rotated to heat the food 6 uniformly in the direction of the concentric circles when the food 6 is viewed from the center of rotation, but the rotation or stop (or the speed may be changed) may be freely set by the rotation motor 22. For example, when the heating temperature sensor 26 determines that the temperature unevenness of the food is occurring, the heating distribution may be changed by the shielding portion 171 and the height driving portion 175 to search for a state in which the temperature unevenness can be eliminated, and when such a state is reached, the rotation may be stopped or the speed may be reduced, or the unevenness may be eliminated quickly.

Fig. 68 is a sectional view of a main part of a high-frequency electric wave heating apparatus according to embodiment 25 of the present invention. The electromagnetic wave supplied from the antenna 30 of the magnetron 2 to the waveguide 3A is transmitted to the left and right of fig. 68 while being repeatedly changed, weakened (node 177 of the electric field) or strengthened (antinode 176 of the electric field) for each 1/4 of g of the wavelength in the tube, with the electric field at the antenna 30 being the maximum (antinode 176 of the electric field). At this time, since the left and right end surfaces of the waveguide are designed as nodes of the electric field, the electric field is aligned in the waveguides 3A and 3C, and the antinodes 176 of the electric field overlap the nodes 177 of the electric field. Here, the in-tube wavelength g is determined by the distance I in the depth direction in fig. 68, and therefore the distance J in the height direction₁There is a degree of freedom, and if the distance from the wall surface 170 facing the antenna 3 is too close (less than 5 mm), an abnormal condition such as discharge occurs, so that it is necessary to maintain a certain distance. The branching point 168 is formed as an electric field node 177 in the waveguides 3A and 3C. This is because the branch point 168 is considered as an opening in view of electromagnetic waves, and the electric field 178A is generated to surround the branch point 168, thereby preventing the electric fields in the waveguides 3A and 3C from being disturbed. The electromagnetic wave propagating from the branch point 168 into the waveguide 3B similarly generates an electric field 178B to surround the branch point 168, and propagates to the left and right at the same in-tube wavelength g because the distance I in the depth direction in fig. 68 is the same. Here, the length from the branch point 168 to the right end 179 is 1/2 times g and the length to the left end 180 is 2/2 times g, so that the electric field in the waveguide 3B repeats electrification regularlyAn antinode 176 of the field and a node 177 of the electric field. On the other hand, since there is no protruding portion such as the antenna 30 in the waveguide 3B, the distance J in the height direction is within a range where discharge does not occur between the wall surfaces₂Can be made smaller. Here take J₂＜J₁And/2, reducing the cross-sectional area to less than half. Here, if the width K of the branch point 168 is too large, the electromagnetic waves of the waveguides 3A and 3C are disturbed in the aligned state, and if it is too small, the energy transmitted to the waveguide B is reduced, so that it is slightly smaller than 1/4 of g. Similarly, the opening 169 for transmitting electromagnetic waves into the heating chamber 4 is slightly smaller than 1/4 in g. The waveguides 3A and 3C are brought into close contact with the waveguide 3B, and share the waveguide wall 181.

Fig. 69 is a main part perspective view of a high-frequency electric wave heating apparatus according to embodiment 26 of the present invention. (although the components are actually connected together, they are shown in a dispersed state for the sake of convenience in the drawing.)

Projections 173A and 173B are formed on the heating chamber 4 and the waveguide 3 so as to surround the opening 169 and the opening 169, respectively, and these projections are formed by forming slits in metal and projecting them. (however, the waveguide 3 has the wall surface forming portion 182 and the projection forming portion 183) the projections 173A and 173B project toward each other, and there is a metallic shielding portion 171 which can be driven in a contact state between the two. The electromagnetic wave in the waveguide 3 is transmitted to the heating chamber 4 only when the shielding portion 171 is not located above the opening portion 169. In order to suppress leakage of electromagnetic waves, the waveguide 3 is connected to the heating chamber 4, and shields electromagnetic waves in the M direction particularly by the sealing portion 174. The sealing portion 174 is made of metal having a groove with a depth N, and N is approximately g/4, so that electromagnetic waves do not propagate from the upper surface 184 of the sealing portion 174 to the M side in the figure. In general, the impedance (difficulty index for propagation to the M side) seen from an electromagnetic wave propagating in the M direction changes with N. The impedance value is expressed by Zin j × Z0 × tan (2 pi N/g), and when N is g/4, | Zin | ═ Z0 × tan (pi/2) ∞ (impedance infinity), the electromagnetic wave cannot propagate from the position 184 to the M side. This impedance is considered in the same manner as in the case of a microstrip line (microstrip line) which is preferably used in a device such as a radio wave seal device of a microwave oven, and various other compact embodiments are available (japanese patent laid-open No. 6-13207).

Fig. 70 and 71 are partial structural views of a high-frequency electric wave heating apparatus according to embodiment 27 of the present invention, and show a case where a plurality of openings 169A and 169B are switched by one driving unit 172 and one shielding unit.

Fig. 70 is a view showing a state where the opening 169A is opened and the opening 169B is shielded, fig. 70(a) is a view showing a main sectional structure, and fig. 70(B) is a view showing a structure below the shielding portion 171 of fig. 70(a) from above. The gear-like drive portion 172 rotates to cause the shielding portion 171 to contact the protrusion 173 between the heating chamber 4 and the waveguides 3B and 3C, thereby switching the openings 169A and 169B through which electromagnetic waves are transmitted. In this case, the opening 169A is opened by overlapping the cutout 185 of the shielding member 171, and the opening 169B is shielded by the shielding member 171.

Fig. 71 is a view showing a state where the opening 169A is shielded and the opening 169B is opened, fig. 71(a) is a view showing a main sectional structure, and fig. 71(B) is a view showing a structure below the shielding portion 171 of fig. 71(a) from above. In this case, the opening 169A is shielded by the shielding portion 171, and the opening 169B is opened by being shifted from the shielding portion 171.

Fig. 72 is a characteristic diagram of the high-frequency electric wave heating apparatus of the present embodiment. This is a graph called a leeke (Rieke) diagram showing the operating point of the magnetron, and shows how easily the electromagnetic wave enters the heating chamber 4. The most accessible to electromagnetic waves is region 186, which is less accessible the further out. It is obvious that the heating efficiency is lowered if the electromagnetic wave cannot enter, and the loss caused by the heat generated at the electromagnetic wave emitting portion is increased. Next, a case where the opening 169A is switched to the opening 169B when an electromagnetic wave is emitted will be described as an example. When the opening 169A is opened and the opening 169B is covered, the operating point is set to 187. However, when the opening 169A is gradually shielded, the opening 169B starts to be opened, the operating point starts to move in the arrow direction, and when the opening is opened by just half, the operating point is 188, and when the opening is completely switched, the operating point returns to 187. That is, it means that the entry of electromagnetic waves becomes difficult during the operation of the shielding portion. In this operation, not only the loss of the electromagnetic wave emitting portion described above is increased, but also various problems such as fluctuation of the oscillation frequency and generation of high-frequency noise may occur depending on the case. Therefore, in the present invention, the problem is solved by controlling the electromagnetic wave emitting unit not to emit electromagnetic waves when the shielding unit 171 is operated.

Fig. 73 is a characteristic diagram of the above embodiment of the present invention, in which the horizontal axis represents time t and the vertical axis represents high-frequency wave output P. Usually, the time t is a time period after the electromagnetic wave emitting section starts emitting the electromagnetic wave_STSince the time is unstable, noise such as high-frequency electromagnetic waves is likely to occur. Therefore, when a detection unit with low noise is conventionally used to detect the state of food 6 at the initial stage of heating, as shown in fig. 73(a), t is the time t_MDuring the detection, the electromagnetic wave is not emitted, after the detection is finished, the electromagnetic wave is emitted, and after t_STReach a stable heating state t_F. Thus, since at t_MThe heating efficiency is extremely poor because no heating is carried out in the time. Therefore, in the present invention, as shown in FIG. 73(b), it is assumed that the heating is started by rapidly emitting the electromagnetic wave so as to pass t as quickly as possible_STT to reach stable heating_FState from t_STThe method of detecting the state of food 6 at the initial stage of heating is started after + Δ t (immediately after stabilization). The state of food 6 can be detected with high accuracy without reducing heating efficiency.

Fig. 74 is a sectional view of the high-frequency electric wave heating apparatus according to embodiment 28 of the present invention.

The electromagnetic wave emitted from the magnetron 2 heats the food 6 on the turntable 1 in the heating chamber 4 through the waveguide 3. At this time, the plurality of openings 169 for guiding the electromagnetic waves from the waveguide 3 into the heating chamber 4 are covered with the transparent opening cover 25 made of a low-loss material which does not easily absorb the electromagnetic waves. A metallic stirring blade 189 as a rotating body is provided in the waveguide 3, and is driven to rotate by a stepping motor 190. Since the stirring blade 189 has various operation modes depending on the purpose, the distance moved from the reference point is constantly monitored by the blade position detector 191. The control means 19 controls the emission of electromagnetic waves from the magnetron 2, determines the operation mode of the stirring blade 189, controls the driving of the stepping motor 190, determines the rotation of the turntable, and stops the driving of the control motor 22, based on a signal input from the operation panel 64 by a user's key operation, a signal from the weight sensor 23 or the state sensor 192 including another temperature sensor, and a signal from the blade position sensor 191. The furnace cover 193 has a door 194 that can be opened and closed freely.

Here, the opening of the plurality of openings 169 that easily emits electromagnetic waves and the opening that does not easily emit electromagnetic waves can be switched depending on the position of the stirring blade 189, and the engagement state can be switched at the same time. In particular, the position and rotational movement of the stirring blade 189 can be freely set based on the signal from the operation panel 64 and the signal from the weight sensor 23 or the other state sensor 192, and therefore, the distribution and the matching state suitable for the heating purpose can be selected. Further, since the rotation and stop of the turntable 1 can be freely set, the turntable 1 can be determined or rotated in accordance with the food 6, and the food 6 can be made uniform in the concentric direction as viewed from the center of rotation, or the turntable 1 can be stopped when the food 6 is milk or liquid food, so that a more preferable matching state can be obtained.

FIG. 75 is a view of the cross-section P-P' of FIG. 74.

The waveguide 3 is enlarged in width midway and has stirring blades 189 formed therein. Since the opening cover 25 is transparent, the user can see the movement of the agitating blade 189 through the 5 openings 169.

Fig. 76 and 77 are sectional structural views of the high-frequency electric wave heating apparatus according to the 29 th and 30 th embodiments of the present invention.

Fig. 76 shows a case where the opening 169 is provided only in front of the stirring vane 189, and fig. 77 shows a case where only one opening 169 is provided in front of the stirring vane 189.

The plurality of openings 169 may be formed by providing the openings 169 at a position farther than the stirring blade 189 as viewed from the magnetron 2 depending on the shape of the heating chamber 4, the height of the turntable 1, and the like, and by extending the waveguide 3 not only in one direction but in a plurality of directions when viewed from the magnetron, or by bending the waveguide so as to extend not only on the rear surface of the heating chamber but also on the side surface, the bottom surface, the top surface, or two or three of them. The stirring blade 189 may have a structure of not only 4 blades but also blades having other numbers of blades, and may not be in the form of a blade as a rotating body, and may be in the form of a plate or a rod.

When the user heats the milk, the user presses the milk button 65 and then the start button 66 on the operation panel 64 shown in fig. 24 after putting the milk into the heating chamber 4. The control means 19 determines that the food 6 is milk based on the signal from the operation panel 64, determines various states such as the amount, shape, and temperature of the milk based on the signals from the weight sensor 23 and the state sensors 192, determines an appropriate position of the stirring blade 189, drives the stepping motor 190 based on the signal from the blade position detector 191, and starts the emission of the electromagnetic wave from the magnetron 2 before and after the determination. At this time, the turntable is kept in a stopped state to stabilize the fitting state, and efficient heating is performed. Thereafter, heating is only applied for a time determined by the weight sensor 23 or the condition sensor 192, or heating is stopped when the milk reaches a suitable temperature. The electric field is concentrated on the bottom surface when the milk is heated, and the good heating distribution can be obtained naturally due to convection, and the milk can be heated in a stable and proper matching state, thereby improving the efficiency.

When the user defrosts meat or fish, the user puts the food 6 into the heating chamber 4, presses the defrosting button 68, and then presses the start button 66. Then, the control means 19 determines that the food 6 is frozen food based on the signal from the operation panel 64, determines various states such as the amount, shape, and temperature of the frozen food based on the signals from the weight sensor 23 and the state sensor 192, determines an appropriate number of rotations of the stirring blade 189, drives the stepping motor to rotate, and starts the emission of electromagnetic waves from the magnetron 2 before and after the rotation. At this time, the turntable 1 is rotated simultaneously with the rotation of the stirring blades 189, so that partial concentration of the electric field is avoided as much as possible. Thereafter, only the time determined by the weight sensor 23 or the state sensor 192 is heated, or the heating is terminated when a suitable temperature is reached (thawing completion). In the case of thawing, partial cooking occurs as soon as the electric field is concentrated, and the problem of temperature distribution is large, so that a good heating distribution is obtained even at the sacrifice of some efficiency.

When the cold dish is to be reheated, the start button 66 is pressed after the food 6 is placed in the heating chamber 4. The control means determines that food 6 is reheated based on the signal from operation panel 64, and determines various states such as the amount, shape, and temperature of food 6 based on the signals from weight sensor 23 and state sensor 192. The important thing is to determine whether the food 6 is in a liquid state, a solid state, or an intermediate state between liquid and solid. One of the methods is to rotate the turntable in an initial short time, stop the turntable, vibrate the food 6, and detect and determine a temporal change in vibration occurring at that time. In summary, this is based on the principle that the liquid vibration lasts for a long time and the solid vibration lasts for a short time. Then, the appropriate operation of the stirring blade 189 is determined, and the stepping motor 190 is driven to rotate, thereby starting the emission of the electromagnetic wave from the magnetron 2. On the other hand, when the food 6 is liquid, the turntable is stopped to stabilize the state of engagement, and efficient heating is performed, as in the case of the milk. When the food 6 is solid, the turntable 1 is rotated to uniformize the heating distribution of the concentric circular shape. When the food 6 is in an intermediate state between liquid and solid, the turntable 1 is repeatedly rotated and stopped. Thereafter, only the time determined by the weight sensor 23 or the state sensor 192 is heated, or the heating is stopped when a suitable temperature is reached. In the case of the liquid food 6, even if the turntable 1 is stopped as in the case of the milk, if the electric field is concentrated on the bottom surface, a good distribution can be naturally obtained due to convection, and heating can be performed in a stable and appropriate matching state, thereby improving efficiency.

Fig. 78 is a characteristic diagram showing the heating efficiency of the above example. FIG. 78 shows a load adjustment state viewed from the magnetron 2A smith chart of states. The hatched portion is a high efficiency region 195 (a region where the efficiency of electromagnetic waves entering the heating chamber 4 is the highest). When the rotary table 1 is stopped and the stirring blade 189 is rotated when a certain food 6 is heated, Q is indicated₁～Q₂～Q₃～Q₄～Q₅～Q₆～Q₇～Q₁…. That is, shows a state in which the fitting state changes depending on the position of the stirring vane 189. While the stirring vanes 189 are stopped at Q₆When the turntable 1 is rotated in a position of the characteristic, Q is displayed₆～Q₈～Q₉～Q₁₀～Q₁₁～Q₆…. In short, the fitting state is shown to change with the rotation of the turntable 1.

In conclusion, the fitting state can be changed depending on the positions of the stirring vanes 189 and the turn table 1.

In this case, in order to maximize efficiency, the stirring blade 189 may be stopped at Q while the turntable 1 is stopped₆The location of the feature. Of course, as in the case of thawing the frozen food, it is sometimes necessary to rotate the frozen food for a good distribution in any case, but in the case of the liquid food 6, it is possible to maximize the efficiency by stopping the frozen food in any case. However, since the characteristics of fig. 78 vary depending on the conditions such as the material, shape, placement position, and temperature of the food 6, there are a method of detecting the matching state by the state sensor 192 or the like, and a method of storing the positions of the turntable 1 and the stirring blade 189, which are optimum for the conditions such as the material, shape, placement position, and temperature of each food 6, as a database in the microcomputer in the control means 19. In this way, the control means 19 can perform the most appropriate heating control based on the information from the operation panel 64, the weight sensor 23, the state sensor 192, and the like, and the database.

Fig. 79 is a sectional configuration view of a high-frequency electric wave heating apparatus according to embodiment 31 of the present invention.

The electromagnetic wave emitted from the magnetron 2 heats the food 6 on the turntable 1 in the heating chamber 4 through the waveguide 3. At this time, a plurality of openings 169 for guiding electromagnetic waves from the waveguide 3 to the heating chamber 4 are provided in the bottom surface of the heating chamber 4, the waveguide 3 has a sub-waveguide 196 branched at a position between the openings 169A and 169B, and a sealing portion 197 for moving in the vertical direction in the drawing, a sealing driving portion 198 for driving the sealing portion 197 to move, a transparent opening cover 25 made of a material which is less likely to absorb electromagnetic waves, and the like are formed in the sub-waveguide 196. The control means 19 controls the emission of electromagnetic waves from the magnetron based on a signal from the operation panel 64 inputted by the user through the buttons and a signal from the weight sensor 23 connected to the turntable 1 to detect the weight of the food 6 or the temperature sensor 26 connected to the food 6, or provides a signal to the seal driving section 198 to move the position of the sealing section 197, or provides a signal to the motor 22 for driving the turntable to rotate to control the rotating operation of the turntable 1, or provides a signal to the turntable height driving section 175 to change the height of the turntable 1, or provides a signal to the electric fan driving section 199 for the electric fan 27 for cooling the magnetron 2 and blowing air to the heating chamber 4 to control the rotating operation thereof.

Here, when the position of the sealing portion 197 is changed, the sealing driving portion 198 can switch between an opening through which electromagnetic waves easily come out and an opening through which electromagnetic waves hardly come out of the plurality of openings 169A and 169B, thereby switching the electric field distribution. In particular, since the position of the sealing portion 197 can be freely set based on the signal from the operation panel 64 and the signal from the weight sensor 23 or the temperature sensor 26, an appropriate electric field distribution can be selected for the heating purpose. In order to accurately determine the position of the sealing portion 197 (not shown), the reference point is set at a certain position, and the position management of the sealing portion 197 is easily considered in accordance with the distance from the reference point.

When the height of the turntable 1 is changed by the turntable height driving unit, the heating distribution of the food 6 can be changed even when the electric field distribution is the same because the height of the food 6 is changed. Thus, similarly, if the turntable 1 is adjusted to the most appropriate turntable height in accordance with the signals from the operation panel 64, the weight sensor 23, and the temperature sensor 26, and the difference in the electric field distribution due to the position of the seal portion 197, an appropriate heating distribution corresponding to the purpose of heating can be selected. Similarly to the seal 197 (not shown), the height of the turntable 1 may be accurately determined by a reference point and a movement distance.

The temperature sensor 26 is composed of a temperature sensor 26A for monitoring the food 6 from the top surface and detecting temperatures and temperature changes at a plurality of positions in the horizontal direction, and a temperature sensor 26B for monitoring the food 6 from the side surface and detecting temperatures and temperature changes at a plurality of positions in the vertical direction, and can detect the temperature distribution of the food 6 substantially over the entire surface. Of course, the same thing can obviously be done if there are temperature sensors 26 in two places, even if not in the horizontal and vertical directions.

In addition, the turntable 1 is usually rotated to make the temperature of the food 6 uniform in the concentric direction as viewed from the rotation center, and the rotation or stop (or the speed can be changed) can be freely set by the motor 22 for driving the turntable to rotate. For example, when it is determined by the temperature sensor 26 that temperature unevenness occurs in the food during heating, the heating distribution can be changed by the seal portion 197 and the turntable height driving portion 175 to search for a state in which the temperature unevenness can be eliminated, and when such a state is reached, the rotation is stopped or the speed is reduced to quickly eliminate the unevenness.

The fan 27 for blowing air cools the magnetron and blows air 200 from the air inlet 201 to the heating chamber 4. The air 200 fed into the heating chamber has some heat due to the heating of the magnetron 2, and thus has some heating effect at most when the food 6 is still cold, and has cooling effect when the food 6 reaches a high temperature. In short, air blow 200 averages the ambient temperature of food product 6. Therefore, when the temperature unevenness is large, the rotation speed is increased to increase the air volume, and the uniformity can be further improved. The air blow 200 is discharged as the air discharge 202 to the outside of the heating chamber 4 from the air discharge port 203 after homogenizing the food 6. Therefore, in order to increase the air volume, there are various methods such as increasing the rotation speed, enlarging the opening size of the air inlet 201, and guiding the air flow to easily enter the heating chamber 4.

Fig. 80 to 81 are main part structural views of the high-frequency electric wave heating apparatus according to the same embodiment, and the sub-duct 196 is seen in the sealing part 197 in operation, and the upper openings 169A and 169B are switched.

Fig. 80 shows a state in which the seal 197 is pulled to the lowermost end in the sub-duct 196 by the movement of the drive shaft 204 driven by the seal driving unit 198. The seal 197 has a structure in which the periphery of the conductive member 205 is covered with a spark-preventing insulator 206, and L1 ≡ L2 ≡ g/4 is used to prevent electromagnetic waves from propagating to the seal end face 207 or less in the figure. On the other hand, at this time, the impedance seen from the perspective of the electromagnetic wave (relative to the ease of propagation from the position 208 to the left side of the electromagnetic wave from the right in the figure to the inside of the waveguide 3) changes at the position 208 near the connection portion between the waveguide 3 and the sub-waveguide 196 due to the length of L3. Specifically, the impedance Zin is j × Z0 × tan (2 pi × L3/g), and when L3 is g/4, | Zin | ═ Z0 × tan (pi/2) ∞ (impedance is infinite), the electromagnetic wave cannot propagate from the position 208 to the left.

Fig. 81 shows a state in which the seal driving unit 198 moves the drive shaft 204 and the seal unit 197 is pulled to the uppermost end in the sub-duct 196. In this case, L3 ═ 0, | Zin | ═ Z0 × tan (0) ═ 0 (impedance of 0) is expressed, and the electromagnetic wave easily propagates from the position 208 to the left side.

Accordingly, the opening 169A is apparently opened and closed by the position of the seal 197. The impedance consideration method of fig. 80 to 81 is the same as the method of considering the microstrip transmission line. Other embodiments are also contemplated.

Fig. 82 shows an embodiment 32 of the present invention, in which the sub-waveguides 196 are connected in different directions. In the case of fig. 82, since the width below the bottom surface of the heating chamber is smaller than that of fig. 79 to 81 due to the sub-waveguide, the ratio of the furnace volume is increased compared with the outer shape, and a compact high-frequency electric wave heating apparatus with a small floor space can be realized.

Fig. 83 to 89 are a characteristic diagram, a main structure diagram, and a flowchart of the high-frequency electric wave heating apparatus of the present invention, and show how the heating distribution is made uniform in relation to the position of the opening 169 and the height of the food 6.

Fig. 83 is a characteristic diagram showing the unevenness of heating distribution obtained when 200cc (full cup) milk is used as the food 6 and heating measurement is performed while changing the height h in the case where the electromagnetic wave is transmitted to the heating chamber 4 only through one of the openings 169A and 169B. The horizontal axis represents the number of open openings, and the vertical axis represents the difference between the maximum temperature and the minimum temperature when the temperature is measured at a plurality of positions, and the smaller the numerical value, the smaller the distribution unevenness. The height of h1 was 10 mm, and the height of h2 was 30 mm, preferably, the height of the opening 169A was 10 mm, and the unevenness was 0 ℃. However, when the same measurement is performed in a microwave oven generally sold, the degree of unevenness is considerably improved by the present example at 2 to 15 ℃. This means that it is preferable to concentrate the electric field on the bottom surface of the food 6 when the liquid food 6 is heated. The electromagnetic wave from the opening 169A heats the bottom surface of the food 6, and a good distribution is naturally formed by convection of the food 6 itself. This is because the uneven distribution in fig. 83 using the opening 168B is caused by the temperature rise in the upper portion of the food 6. The electromagnetic wave easily enters the upper portion because the opening is located away from the bottom surface of the food 6.

Fig. 84 is a sectional view of the essential part of the optimal condition opening 196A of fig. 83, which is 10 mm in height.

In the example of the operation panel 64 of fig. 24, the milk button is configured as a dedicated button, and therefore, when the user heats milk, the user presses the milk button 65 after putting milk into the heating chamber 4, and then presses the start button 66. Then, the control means 19 judges that the food 6 is milk based on the signal from the operation panel 64, and while judging various states such as the amount, shape, temperature, etc. of the milk based on the signals from the weight sensor 23 and the temperature sensor 26, the electromagnetic wave is emitted from the opening 169A in the plurality of openings 169, and the electromagnetic wave is controlled to be emitted from the magnetron 2 before and after the height is controlled to 10 mm and the structure is otherwise made appropriate. After which the heating is stopped for a time determined by the weight sensor 23 or the temperature sensor 26, etc., or when the milk temperature is appropriate. Thereby easily achieving a cooking state with a good heating distribution.

Fig. 85 is a characteristic diagram of a case where 100 g of frozen beef chips were used as the food 6 and the thawing treatment was performed. The most preferable conditions are the opening 169A and a height of 30 mm. However, the same measurement was carried out in a commonly available microwave oven, and the degree of unevenness was about 32 to 60 ℃ and was improved by the present example. In this case 100 g sliced beef is a representative shape with a small thickness t and a light weight even in the food product 6.

Fig. 86 is a sectional view of the opening 169A and a main part having a height of 30 mm in the optimum condition of fig. 85.

FIG. 87 is a graph showing characteristics of a food 6 prepared by thawing 300 g of frozen beef chips. The most preferable conditions are 169B for the opening and 10 mm for the height. However, the same measurement was carried out in a commonly available microwave oven, and the unevenness was about 32 to 75 ℃. In this case, the 300 g sliced beef is also a standard-shaped food product having a thickness and a weight which are also common in the food product 6.

FIG. 88 is a sectional view of the essential part of FIG. 87, wherein the most preferred conditions are an opening 169B and a height of 10 mm.

When the user defrosts the frozen meat or fish food, the user presses the defrosting button 68 and then the start button 66 after putting the food 6 into the heating chamber 4 using the operation panel 64 of fig. 24. Then, the control means 19 judges that the food 6 is frozen food based on the signal from the operation panel 64, judges various states such as the amount, shape, temperature, etc. of the frozen food based on the signals from the weight sensor 23 and the temperature sensor 26, and controls the opening 169 and the height h to be appropriate, before and after which the magnetron starts emitting electromagnetic waves. Then, heating is performed for a time determined by the weight sensor 23 or the temperature sensor 26, and the heating is stopped when a suitable temperature is reached (thawing completion).

Also, in the case of automatic cooking without a dedicated button, for example, when re-heating a dish, the start button 66 is pressed after putting the food 6 into the heating chamber 4. Then, the control means 19 determines whether or not the food 6 is reheated based on the signal from the operation panel, and determines various states such as the amount, shape, and temperature of the food 6 based on the signal from the weight sensor 23 or the temperature sensor 26. Wherein it is also judged whether the food product 6 is liquid or solid. In one method, the food 6 is vibrated by rotating the turntable 1 for a short time first and then stopping the rotation, and the change with time of the vibration generated at this time is detected to perform the judgment. In short, the principle is based on the fact that if the liquid is a liquid, the vibration takes a long time, and if the solid is a solid, the vibration disappears in a short time. Then, the opening 169 is controlled to have an appropriate height h, and the magnetron 2 is started to emit electromagnetic waves before and after this, and the turntable 1 is rotated again, so that the heating distribution on the concentric circle is made uniform. Then, heating is performed for a time determined by the weight sensor 23 or the temperature sensor 26, or heating is stopped when a suitable temperature is reached. When the food 6 is liquid, the electric field is concentrated on the bottom surface as in the case of the milk, and a good distribution state can be naturally obtained by convection.

In addition, there is a method of constantly heating the food 6 uniformly and eliminating the unevenness of the heating distribution, in which the optimum opening position 169 and the information of the height h are stored in advance as a database in a microcomputer in the control means for each condition such as the material, shape, placement position, temperature, etc. of the food 6. In this way, the control means 19 compares the outputs of the operation panel 64, the weight sensor 23, the temperature sensor 26, and the like with the database, can perform optimum heating control,

fig. 89 is an example of a flowchart of the configuration of fig. 79 to 82, and shows a procedure for determining the most suitable position and height h of the opening 169. Step 209 represents an initial state, where the height h is 10 mm and the position L3 of the seal 197 is 0. Step 210 is a determination made by the weight sensor 23 as to whether the food item 6 is liquid, has a weight m that is less than m1, or is heavier than m1 and lighter than m2, or is heavier than m 2. In step 211, the seal driving unit 198 starts to move the seal 197 to the proper position L3. Step 212 is a determination, using the temperature sensor 26 or other sensors, of whether the thickness t of the food product 6 is greater than t1, or less than t1 and greater than t2, or less than t 2. Step 213 starts the level of the food product 6 to the appropriate height h by the turntable height drive 175. The opening 169 and the height h are set appropriately according to the material (liquid or not), the weight m, and the thickness t of the food 6 as described above.

Here, although fig. 89 describes a procedure for determining the opening portion 169 and the height h suitable in the initial state, it is needless to say that, as another example, it is also conceivable to feed back a change in the state of the food 6 (particularly, a change in temperature with the progress of heating) and change the position and the height h of the opening portion 169 several times to eliminate the uneven distribution at that time.

It is also described that even if the food 6 is made of the same material, the opening 169 and the placement height h must be switched to obtain the optimum distribution if the weight is different.

In the present invention, after each heating stop, the opening portion was set at 169A and the height h was set at 30 mm in preparation for use in processing a small amount of food 6. This is because the shorter the heating time of the light food, the more the heating time is to be prevented from being prolonged because the heating is started in a state where the heating efficiency is not good, and the heating time is not sufficiently improved until the heating is stopped even if the switching is performed halfway. In contrast, when a large amount of food 6 is processed, the time until the heating is stopped is long, and therefore, there is sufficient time for switching in the middle. In practice, the user first starts the emission of electromagnetic waves by the magnetron and starts the rotation of the turntable 1 when heating the food product 6. Then, during the heating process, various states such as the amount, shape, and temperature of the food 6 are determined based on signals from the temperature sensor 26, the weight sensor 23, and the other state sensors 192 (e.g., the optical sensors 61 and 62). Since the small amount of food 6 is heated in the initial state, when it is determined that a large amount of food is present, the opening 169 and the height h are controlled to be appropriate, and heating is performed for a predetermined time set by the user before and after the determination, or heating is stopped when it is determined that an appropriate temperature is reached by various sensors.

FIGS. 90 to 95 are structural views showing simulation results of an internal electric field of the high-frequency electric wave heating apparatus.

Fig. 90 is a perspective view of a high-frequency electric wave heating apparatus according to an embodiment of the present invention. Electromagnetic waves are excited by the antenna 30 of the magnetron 2.

Fig. 91 and 92 are perspective views each showing an electric field distribution (in the case of no food) of the high-frequency electric wave heating apparatus of fig. 90 at a cross section S-S' and showing electric fields generated in a resonance state by lines of equal electric field intensity. (it is considered that the stronger the electric field (antinode) is at the inner side of the annual ring pattern), this indicates the difference in electric field distribution due to the difference in the position of the opening 169.

Fig. 91 shows a case where only the 1 st opening 169A is opened, and four antinodes of an electric field are generated in the X direction, three antinodes of an electric field are generated in the Y direction, and one antinode of an electric field is generated in the Z direction in the heating chamber 4.

Fig. 92 shows a case where only the 2 nd opening 169B is opened, and five antinodes of the electric field are generated in the X direction, one antinode of the electric field is generated in the Y direction, and one antinode of the electric field is generated in the Z direction in the heating chamber 4.

Fig. 93 is a perspective view of a flat food 6 (shaomai, etc.) heated in the high-frequency electric wave heating apparatus of fig. 90.

FIGS. 94 and 95 are perspective views of a U-U' cross section showing a distribution of dielectric loss in the case where the food of FIG. 93 is placed on the 1 st opening 169A of the high-frequency heating apparatus of FIG. 90 and electromagnetic waves are inputted. The more the slope is, the more the loss is, and the more the temperature is raised.

Fig. 94 shows a case where only the 1 st opening 169A is opened, and shows a case where the bottom center 214 of the food item 6 is heated.

Fig. 95 shows a case where only the 2 nd opening 169B is opened, and shows a case where the end 215 of the food item 6 is heated.

Here, it is explained why the electric field distribution like that shown in fig. 91, 92 is generated.

First, propagation of electromagnetic waves in the waveguide 3 will be described.

Fig. 96 is a sectional view of a main part of the high-frequency electric wave heating apparatus. The magnetron 2, the waveguide 3, the heating chamber 4, and the opening 169 are simply shown. The distance L4 between the antenna 30 of the magnetron 2 and the center 216 of the opening 169 is an odd multiple of g/4, where g represents the wavelength of the electromagnetic wave propagating to the left in the waveguide 3 (in-tube wavelength). This is because the electromagnetic wave propagates to the left of the graph 96 while repeating its intensity depending on the in-pipe wavelength g determined by the shape of the waveguide 3 when propagating through the waveguide 3, and the electric field is inevitably weakened at a position which is an odd multiple of g/4. Here, L4 is g × 9/4. The arrows of the solid line indicate the direction of the strong electric field, and the direction of the electric field (and the magnetic field) is reversed every g/2, and therefore every other time from the antenna 30

The direction of the arrow g/2 is reversed once and the two are repeated back and forth at a frequency of 2.45 GHz. In fig. 96, since the opening 169 of the heating chamber 4 is connected to a place where the electric field (and the magnetic field) is weak, the electric field in the waveguide 3 is not disturbed, and the electric field easily enters the heating chamber 4 with high efficiency. However, in fig. 79, the opening 169A is connected to the heating chamber 4 at a position where the electric field (and the magnetic field) is weak, and the opening 169B is connected to the heating chamber 4 at a position where the electric field (and the magnetic field) is strong. This is because, when the position L3 of the sealing portion 197 is 0, the electromagnetic wave is allowed to smoothly enter the heating chamber from the opening 169A as much as possible, and the electromagnetic wave is prevented from entering the heating chamber 4 from the opening 169B. On the other hand, when the position L3 is g/4, the electromagnetic wave is not propagated to the opening 169A as described above, and the electromagnetic wave inevitably enters the heating chamber 4 only from the opening 169B. Accordingly, changing the position L3 of the seal 197 allows the openings 169A, 169B to be apparently switched.

In the conventional example of fig. 4, the end faces 14 of the two sub waveguides 13 facing the two openings 5 are moved to open and close the two openings 5 independently, but in the present invention, the opening 169A is formed at a place where the electric field is weak, the opening 169B is formed at a place where the electric field is strong, and the sealing part 197 is provided therebetween, so that the openings 169A and 169B can be switched even with only one sealing part.

Here, the definition of the in-tube wavelength g of the wave propagating through the waveguide 3 will be described with reference to fig. 96, where C is the depth of the waveguide 3, D is the thickness, the number of peaks of the intensity of the electromagnetic wave in the depth direction is m, the number of peaks of the intensity of the electromagnetic wave in the thickness direction is n, and the in-tube wavelength g is expressed by the following equation (4) if the wavelength of the electromagnetic wave in vacuum is about 122 mm. In general, m is 1 and n is 0, and g is represented by formula (5). If C is 80 mm and D is 40 mm, g is about 188 mm. (these dimensions are all internal dimensions excluding the thickness of the plate)

g＝/√〔1-²((m/2C)²+(n/2D)²)〕……(4)

g＝/√〔1-²(1/2C)²〕……(5)

The electromagnetic wave resonance in the heating chamber 4 at this time will be described below.

In the case of fig. 96, the electromagnetic wave in the heating chamber 4 is almost resonated, but strong electric fields 217 and 218 (solid arrows) in opposite directions are generated across the opening 169, so that the opening 169 in the heating chamber 4 is stabilized in a resonant state in which the electric field is weakened (nodal). The electromagnetic wave enters the heating chamber 4 most efficiently. (however, the transmission state is different from the transmission state in the waveguide 3 in the resonance state, and the phase of the electric field and the magnetic field is different by 90 °) in the resonance state

The resonance state is determined by the shape of the heating chamber and the position of the opening, and in the case of fig. 91 showing the electric field distribution in the heating chamber 4 at this time, 4 strong electric fields are generated in the X direction of the heating chamber 4, 3 strong electric fields are generated in the Y direction, and 1 strong electric field is generated in the Z direction. This is because the resonance is achieved, and the electromagnetic wave in the heating chamber forms antinodes of an electric field in a standing wave distribution, and the number of antinodes is called a wave mode. In general, when the shape of the heating chamber 4 is expressed in three dimensions and the dimensions in each direction are expressed in x, y, and z, if there are only m, n, and p antinodes of the electric field in each direction, the wave mode is (mn p). In the present embodiment, since the center positions of the depth x and the width y of the bottom surface of the heating chamber 4 are substantially aligned with the center position of the 1 st opening 169A and a strong electric field is generated across the opening 169 (node is formed in the opening 169A), an even-numbered mode (m is an even number) is easily generated in the depth x direction and an odd-numbered mode (n is an odd number) is easily generated in the width y direction, and other modes are not easily generated. Fig. 91 is a wave mode (431), and fig. 92 is a wave mode (511) as can be easily understood.

In conclusion, it can be said that the distribution of the electric field (i.e., the heating distribution) can be changed by the position of the opening portion 169.

For reference, when the food 6 is not present in the heating chamber and the heating chamber 4 is a rectangular parallelepiped, the heating chamber can be considered as a cavity resonator, and the wave mode that may be generated can be obtained from the size of the heating chamber 4 and the position of the opening 169. When the dimensions of the heating chamber 4 are x, y, and z, the wave moduli generated in the respective directions are combinations of m, n, and p satisfying the expression (6). (x, y, z are in millimeters, and m, n, p are integers)

1/λ²＝(m/2x)²+(n/2y)²+(p/2z)² ……(6)

On the other hand, in the case of food 6, the dielectric constant of the food is affected by the wavelength compression, and the like, and as a result, the formula (6) is deviated. However, it has been experimentally found that even with the food 6, the wave mode satisfying the formula (6) tends to be generated in the vicinity of the opening 169 and to be disturbed at a position away from the opening 169. As an example of generating the wave mode (431) at about 122 mm, a size x of 330 mm, y of 300 mm, z of 215 mm, or the like, which substantially satisfies the formula (6), may be selected.

In order to obtain a heating distribution targeted for food 6, it is considered that the opening 169 should be formed in the vicinity of the food 6, and in the present invention, a plurality of openings 169A and 169B causing different electric field distributions are formed in the wall surface of the heating chamber 4 closest to the food 6, that is, the bottom surface of the heating chamber 4.

Fig. 97 is a sectional view of a high-frequency electric wave heating apparatus according to embodiment 33 of the present invention.

In fig. 97, electromagnetic waves from a magnetron 2 heat food 6 placed on a tray 219 in a heating chamber 4 through a waveguide 3. The openings 169C and 169D for connecting the waveguide 3 and the heating chamber 4 to guide the electromagnetic wave are configured such that the 1 st opening 169C is located at the center of the heating chamber 4 and the 2 nd opening 169D is located close to the magnetron 2, and the portion (node) of the electromagnetic wave propagating in the waveguide 3 where the electric field is weak and the portion (node) of the electromagnetic wave distributed as a standing wave in the heating chamber 4 where the electric field is weak are connected to each other. On the other hand, in order to improve the heating efficiency and the heating distribution of food 6, opening shielding part 220 is provided so as to cover openings 169C and 169D, and has a disk-like structure having electromagnetic wave transmitting part 221 made of a low-loss material that does not easily absorb electromagnetic waves and electromagnetic wave shielding part 222 made of a metal material, and is driven to rotate by rotating shaft 223 made of a low-loss material that does not easily absorb electromagnetic waves. The rotary shaft 223 penetrates the heating chamber 4 and the waveguide 3 at a position between the openings 169C and 169D, and is connected to and driven by a motor 224 as a driving unit. In response to this driving, the apparent opening position through which electromagnetic waves can be transmitted from the waveguide 3 into the heating chamber 4 is changed (the 1 st opening 169C and the 2 nd opening 169D are switched), and the electric field distribution is changed. The rotation shaft 223 is also connected to the 1 st gear 225, and the 1 st gear 225 transmits the rotational power to the 2 nd gear 226. The 2 nd gear 226 is connected to the turntable 1, rotates the food 6 to make the concentric directions uniform as viewed from the rotation center, and has a number of teeth different from that of the 1 st gear 225 (the number of teeth of the 2 nd gear 226 is large in the present embodiment) to make the uniform. The shape recognition sensor 227 recognizes the shape of the food 6, and sends a signal to the control means 19, and the control means controls the operations of the magnetron 2, the motor 224, the electric fan 27 for cooling the magnetron 2, and the like based on the signal. In this case, an optimum power supply method (switching mode of the openings 169C and 169D, electromagnetic wave emission mode of the magnetron 2, and the like) is set in advance according to the shape of the food, and switching is performed according to a signal from the shape recognition sensor 227. Further, a cover 225 is used for safety to cover the opening shielding portion 220 and the like, and the turntable 1 is supported by a support portion 228.

FIG. 98 is a view of the cross section V-V' of FIG. 97.

The center of the 1 st opening 169C is provided at the center (center in the vertical direction and center in the horizontal direction) of the bottom surface of the heating chamber 4, and the 2 nd opening 169D is provided at a position closer to the magnetron. The openings 169C and 169D are rectangular and parallel to the four sides of the bottom surface of the heating chamber 4, which is also rectangular.

FIG. 99 is a cross-sectional view W-W' of FIG. 97.

The opening shielding portion 220 covers the openings 169C and 169D, and a semicircular electromagnetic wave shielding portion 222 is provided in the circular electromagnetic wave transmitting portion 221 and driven by the rotation shaft 223. In the case of fig. 99, the electromagnetic wave shielding portion 222 prevents the electromagnetic wave in the waveguide 3 from easily entering the heating chamber 4 through the 1 st opening 169C and easily enters the heating chamber 4 through the 2 nd opening 169D. On the other hand, when the rotation shaft 223 rotates half a turn, the electromagnetic wave in the waveguide 3 is likely to enter the heating chamber 4 through the 1 st opening 169C, and is unlikely to enter through the 2 nd opening. Thus, the opening portions 169C and 169D are apparently switched by the rotation of the opening blocking portion 220.

In the present embodiment, the opening blocking portion 220 and the turntable 1 are both rotated by being driven by one rotation shaft 223. Of course, a structure in which the rotating shafts are provided separately to achieve further uniformity may be adopted. The opening shielding portion 220 is configured to rotate in the heating chamber 4, but may be configured to linearly move in the left-right direction in the waveguide. The motor 224 is most simply configured to rotate at a constant speed by a simple ac motor, but may be further uniformized by fine control using a stepping motor. The 2 nd opening 169D is formed in the bottom surface of the heating chamber 4, but may be formed in another wall surface of the heating chamber 4. The shape recognition sensor 227 performs control based on a signal, but the detection unit may be configured by another detection means.

Fig. 100 is a view showing how the electric field is bent when a flat (thin) food 6 is placed in the center of the heating chamber 4 (i.e., above the 1 st opening 169C). The food 6 generates a strong electric field 231 inside the food, bends a pair of strong electric fields 229 and 230 in opposite directions generated across the opening 169C, and is heated by the electric power P shown in formula (1) due to the strong electric field 231 inside the food and the dielectric constant of the food 6. At this time, the lower portion of the center of the food 6 generates the heat generating portion 232, and the inside of the food 6 is heated without cooking the edge portion. This is the same loss profile as the dielectric loss profile shown in fig. 94. But the center lower portion of the food 6 is overheated and the edge is still cold, which is a problem opposite to that of the existing microwave oven. Thereby switching between the above-described 2 nd opening 169D to achieve uniformity. Empirically, the food 6 becomes hot unless it is an opening in the center of the bottom surface of the heating chamber 4 (immediately below the food). This is because the electric field distribution in the heating chamber 4 is disturbed by the food 6 itself at the opening portion other than the center of the bottom surface, and only the electric field having an orientation covering the edge of the food is generated at a position apart from the opening portion. Even when the opening 169C is located at the center of the bottom surface of the heating chamber 4 (directly below the food), the electric field distribution becomes irregular as the distance from the opening increases, and the stable strong electric fields 229 and 230 are maintained in the vicinity of the opening 169C, so that the interior of the food 6 is heated and is not cooked to the edge. (in fig. 100, only the strong electric field deformation portions 233 are scattered, but in an extreme case, three or two strong electric fields 234 may be provided on the top surface of the heating chamber 4) and the food is usually placed in the center of the heating chamber 4, so that the 1 st opening 169C must be selected in the center of the bottom surface of the heating chamber 4, and it is obvious that the 2 nd opening 169D is freely installed.

Fig. 101 to 104 are cross-sectional views of the heating chamber 4, and how the electric field is generated varies with the position of the opening on the wall surface will be described.

In order to establish a mode satisfying equation (6) with the heating chamber 4 as a cavity resonator, it is preferable to determine the position of the opening as shown in fig. 101 and 103. (but here considered two-dimensional for simplicity of illustration).

FIG. 101 shows that strong electric fields 235 and 236 are generated in opposite directions across the opening 169E to establish (22)Wave mode. Thus, the same is established (even,the wave mode of (a) is easily taken into account.

FIG. 102 shows that strong electric fields 237 and 238 are generated in opposite directions across the opening 169F to establish (23)Wave mode. Thus, the same is established (even, odd, etc.),(odd, even, and,The wave mode of (a) is easily taken into account.

FIG. 103 shows that strong electric fields 239 and 240 are generated in opposite directions across the opening 169G to establish (33)Wave mode. Thus, the same is established (odd, etc.),The wave mode of (a) is easily taken into account.

However, fig. 104 shows that strong electric fields 241 and 242 are intended to be generated in opposite directions across the opening 169H, but the wave mode described in equation (6) is not formed, and the electric field distribution cannot be estimated. This is because the wall surface of the heating chamber 4 is not parallel to the opening 169H.

As described above, according to the present invention, the wall surface of the heating chamber 4 is parallel to the opening 169 to generate a desired electric field.

FIG. 105 is a characteristic diagram showing the heating efficiency of example 34 of the present invention. Fig. 105 is a smith chart showing a reflection state (a fitting state) seen from the magnetron 2, and a hatched portion is a high efficiency region 195 (a region where electromagnetic waves enter the heating chamber 4 with the highest efficiency). In this case, the reflection characteristics in the case where only the 1 st opening 169C and the 2 nd opening 169D are opened are set as 243 and 244, and both are in the high efficiency region 195, and adjustment is made so that the rated output value can be output. So that uniform heating can be performed as described above while improving heating efficiency.

Figure 106 is a plan view of a shoji 245 placed on a tray 219, viewed from above, representing a flat food item. When the microwave oven of the related art shown in fig. 1 is heated, the characteristics shown in fig. 107 are obtained. In fig. 107, the horizontal axis represents the time after the heating was stopped and the vertical axis represents the temperature. The average temperature of 4 trades in the central part 246 (hatched part) of the trades 245 is X₁The average temperature of 12 trades in the peripheral portion 247 (non-hatched portion) of the trade 245 is X₂The surrounding portion 247 is shown to be hotter than the central portion 246. This represents the characteristic of existing microwave ovens that flat food like shaomai is easy to heat at the edges and not easy to heat at the center.

Fig. 108 is a characteristic diagram showing temperature variations when the 16 trades 245 in fig. 106 are heated by the high-frequency electric wave heating apparatus of the present invention. The horizontal axis represents the time after the heating was stopped, and the vertical axis represents the temperature, which is the average temperature X of 4 trades in the central part 246 of the trades 245₁And the average temperature X of the 12 trades in the area 247 surrounding the trades 245₂Substantially the same indicates that heating was performed more uniformly than in fig. 107.

However, if the plurality of openings are adjusted individually, it cannot be said that the result of fig. 108 is always obtained. Although it is good that the 1 st opening 169C and the 2 nd opening 169D tend to heat the central portion 246 and the peripheral portion 47, respectively, the temperature does not rise at exactly the same rate. For example, as in FIG. 109, an average temperature X of the center portion 246 may occur₁Average temperature X of peripheral portion 247₂High (contrary to the existing characteristic diagram 107). This is because the number of trades is 12 in the peripheral portion 247 and 4 in the central portion 246, and even if the same amount of electromagnetic waves enter the heating chamber 4 from the openings 169C and 169D, respectively, the electromagnetic waves may enter the central portionSection 246 heats up quickly. Fig. 110 to 113 show embodiments 35 to 37 of the present invention as a solution for changing the temperature balance between the center temperature and the ambient temperature.

Fig. 110 shows an example in which, as the 35 th embodiment, the opening area of the 1 st opening 169C is made smaller than the opening area of the 2 nd opening 169D to reduce the amount of electromagnetic waves entering the heating chamber 4 from the 1 st opening 169C, unlike the structure of fig. 98. As a result, the increase in the center temperature is suppressed, and the characteristics shown in fig. 109 can be optimized to the characteristics shown in fig. 108.

Fig. 111 shows an example of the 36 th embodiment, which is different from the characteristics shown in fig. 105 and deviates from the reflection state (adjustment state) at the 1 st opening 169C. The characteristic 244 at the 2 nd opening 169D is still maintained in the high efficiency region, and the characteristic 243 at the 1 st opening 169C is deviated as shown in fig. 111. As with the effect of fig. 110, the amount of electromagnetic waves entering the heating chamber 4 from the 1 st opening 169C is reduced (reflection is increased), and the increase in the center temperature is suppressed, so that the characteristic shown in fig. 109 can be optimized to the characteristic shown in fig. 108.

Fig. 112 to 113 show the ratio of the opening time of the openings 169C and 169D changed as example 37. FIG. 113 is a cross-sectional view taken along line Y-Y' of FIG. 112.

In fig. 112, the electromagnetic wave shielding portion 222 has a shielding protrusion 248 and a shielding opening 249, which are different from those in fig. 97. In this case, the 2 nd opening 169D is opened most of the time when the opening shielding part 220 rotates one cycle, the shielding protrusion 248 is positioned on the 2 nd opening 169D, and the 1 st opening 169C is opened only when the shielding opening 249 is positioned on the 1 st opening 169C. As a result, the increase in the center temperature is suppressed, and the increase in the ambient temperature is promoted, so that the characteristics shown in fig. 109 can be optimized to the characteristics shown in fig. 108.

Further, a stepping motor (not shown) is used as the motor 224, and the rotation of the opening blocking portion 220 is not necessarily required, and the time during switching between opening and closing of the openings 169C and 169D is shortened as much as possible in terms of structure. For example, as shown in fig. 105, even if the characteristics 243 and 244 of either of the openings 169C and 169D can be realized, there is a high possibility that the reflection increase efficiency is lowered in the middle stage of switching (for example, in the case where the openings 169C and 169D are each opened by half). Therefore, the opening blocking portion 220 is operated at a high speed only at this time, and the heating efficiency can be prevented from being lowered as much as possible.

In this embodiment, a flat food is taken as an example, and the improvement of the heating efficiency and the uniformization of the heating distribution are described. However, there are various kinds and shapes of food and the influence of the plate must be considered. Therefore, as an example other than this embodiment, there are various optimization methods such as changing the balance of the opening times of the openings 169C and 169D according to the food.

In the embodiment, the local heating is described for heating a relatively small portion such as shaomai and thawing of sliced beef, but the present invention is not limited to this, and an example in which a portion over a wide range is locally heated such as switching between the center and the outside of a single tuna is also conceivable.

As described above, the high-frequency electric wave heating apparatus according to the present invention has the following effects.

Since the local heating means can heat an arbitrary portion of the object, it is possible to make the entire heating distribution uniform, or to clearly distinguish the heated portion from the non-heated portion.

If a protective means for protecting the local heating means is provided between the object to be heated and the local heating means, heating of any part of the object to be heated is not hindered in any case, and therefore, there is no problem that the local heating means cannot be operated due to impact of fragments of the object to be heated or the direction of electromagnetic waves is influenced by absorption of electromagnetic waves by the fragments of the object to be heated, and there is an effect that the local heating is not influenced. Therefore, the target portion can be stably heated locally.

The local heating means is located under the stage, and if the protection means is located between the stage and the local heating means, the local heating means is also protected by the stage. If the local heating means is often located close to the object to be heated, the electromagnetic wave can be directly emitted to the target region of the object to be heated without being reflected by other wall surfaces, and therefore, there is an effect that local heating is more easily performed.

If the object to be heated is placed on the protection means and the local heating means is located under the protection means, the protection means can be used as well as or integrated with the stage, so that the structure can be simplified, the number of parts can be reduced, and the overall size, weight and price can be reduced.

If at least a part of the protective means is a dielectric, the dielectric can protect the local heating means, and the electromagnetic wave from the local heating means can be emitted into the heating chamber through the dielectric, so that the target portion can be easily heated locally.

The local heating means has a waveguide portion for guiding the electromagnetic wave emitted by the electromagnetic wave emitting means and a radiation portion for radiating the electromagnetic wave guided by the waveguide portion into the heating chamber, and the distance through which the electromagnetic wave from the electromagnetic wave emitting means to the radiation portion passes is generally substantially constant. Moreover, the heating efficiency is high, and as a result, the heating time is shortened and energy is saved.

If the distance from the electromagnetic wave emitting means to the radiation part for passing the electromagnetic wave is approximately an integral multiple of g/2 (g is the wavelength of the electromagnetic wave on the path through which the electromagnetic wave passes), the electric field in the radiation part becomes strong, and therefore, the efficiency is extremely high when the object to be heated is placed close to the radiation part.

When an electromagnetic wave coupling part having a radiation part is connected to a driving means, the driving means is controlled to rotate the radiation part around the electromagnetic wave coupling part, and the position of radiation of the electromagnetic wave from the radiation part is changed by the control of the driving means, so that the position of heating the object can be freely changed. Thereby having an effect of easily achieving local heating.

The waveguide section has a waveguide connecting the electromagnetic wave emitting means and the heating chamber, and if the electromagnetic wave coupling section is used as a passage into the waveguide and the heating chamber, the electromagnetic wave coupling section functions as an antenna to efficiently guide the electromagnetic wave in the waveguide to the heating chamber, thereby further improving the heating efficiency.

If the distance from the electromagnetic wave emitting means to the electromagnetic wave coupling portion through which the electromagnetic wave passes is approximately an integral multiple of g/2 (g is the wavelength of the electromagnetic wave on the path through which the electromagnetic wave passes), the electric field becomes strongest at the position of the electromagnetic wave coupling portion when a standing wave is generated on the electromagnetic wave path, and therefore the electromagnetic wave coupling portion has an effect of guiding the electromagnetic wave in the waveguide into the heating chamber with the highest efficiency.

If the radiating portion is located under the object to be heated, since the radiating portion is often located near the object to be heated, the electromagnetic wave can be directly radiated to the target portion of the object to be heated without being reflected by other wall surfaces, and therefore, there is an effect that local heating can be performed more easily.

The heating chamber has a stage on which an object to be heated is placed, and if the center of the stage is located at substantially the center of the heating chamber, the stage can be made large, and the space in the heating chamber can be effectively used. Thus, it is possible to place objects having a large size or to place a large number of objects. As a result, the user can use it conveniently.

If the stage driving means is controlled to rotate the stage with the center of the stage as the rotation center, the vertical movement of the stage during rotation can be suppressed to realize stable driving, and thus, the target heating portion can be easily heated locally. The object to be heated is also less likely to vibrate, and the object is less likely to be knocked over.

If the control of the local heating means is performed in conjunction with the control of the stage driving means, the position of the local heating means can be easily grasped and changed with respect to the object to be heated. Thereby having an effect of more easily heating the target heating position.

If the control of the local heating means and the control of decelerating and stopping the stage driving means are performed simultaneously or sequentially, the state can be maintained for a long time when the local heating means and the stage driving means are in the most suitable positional relationship for the local heating. The local heating of the target heating portion can be performed without fail, and the local heating time can be shortened.

If the driving means is controlled so that the range of driving of the radiation part is inside the bottom surface of the heating chamber, the space required for driving and the space outside the heating chamber can be reduced. And the electromagnetic wave is not easy to leak from the driving range to the outside of the heating chamber, so that a special sealing structure is not needed, and the electromagnetic wave heating device has the effects of miniaturization, light weight and low price of the whole device due to simple structure and few parts.

If the stage has an electromagnetic wave shielding part made of a conductive material and an electromagnetic wave transmitting part near the center, the effect of locally heating the vicinity of the center of the bottom surface of the object to be heated is obtained.

If the direction of the electromagnetic wave from the radiation unit is controlled to be switched between the direction in which the object is heated and the direction in which the object is not heated, the direction can be switched between local heating in which the electromagnetic wave is directly radiated to the object to be heated and heating with the electromagnetic wave reflected by the wall surface of the heating chamber without local heating. Therefore, the electromagnetic wave can be concentrated or not concentrated according to the purpose of use, and the heating distribution can be more freely changed.

If the local heating means is controlled to switch between heating the object at substantially the center of the bottom surface and heating the object at substantially the periphery, there is an effect that the heating distribution of the object can be made uniform by a simple method.

If the local heating means is controlled to switch the heating location of the object to be heated between two-dimensional and three-dimensional spaces, the effect of the heating distribution may be more finely changed.

If there is an intermittent control means for intermittently controlling the local heating means, the heating area of the object to be heated can be intermittently switched, and the electromagnetic wave can be concentrated on a limited portion, so that the heating distribution can be more freely changed.

If there is a continuous control means for continuously controlling the local heating means, the heating site of the object to be heated can be continuously switched, so that local concentration of heating can be avoided, and an effect of uniformly heating a wide area can be obtained.

If there are intermittent control means for intermittently controlling the local heating means, continuous control means for continuously controlling the local heating means, and switching control means for switching the intermittent control means and the continuous control means, it is easy to perform switching in accordance with the purpose.

If the setting means which can be set by the user is provided and the local heating means is controlled by the setting means, the effect of realizing the appropriate local heating according to the setting content can be obtained.

If at least one of a physical quantity of an object to be heated and a variation thereof or a physical quantity indicating a state in a heating chamber or a variation thereof is provided as detection means for detecting a detection quantity, and local heating means is controlled based on the detection quantity of the detection means, there is an effect that appropriate local heating can be carried out according to the state of the object to be heated itself and the state in the heating chamber.

If the local heating means is controlled by the temperature distribution detecting means for detecting the temperature distribution of the object to be heated, the local heating means is controlled based on the actual temperature information, and thus the optimum local heating can be achieved.

If at least one of a shape detecting means for detecting the shape of the object to be heated and a weight detecting means for detecting the weight of the object to be heated is provided, the state of the object to be heated can be roughly determined even without heating. This prevents wasteful heating, and further improves the efficiency of local heating.

If the area determination control means is provided which can determine the area to be heated by at least one of the shape detection means and the weight detection means before and after the start of heating, the area to be heated can be determined regardless of whether the heating is started or not, and therefore, only the area, that is, the object to be heated can be efficiently and locally heated.

If the control of the local heating means and the control of the electromagnetic wave emitting means are performed in conjunction, the electromagnetic wave can be emitted only in a state where a portion to be locally heated can be heated, or the electromagnetic wave can be not emitted in a state where a portion not to be locally heated can be heated, and heating can be more carefully controlled.

If the local heating means is controlled after the electromagnetic wave emitting means is controlled to reduce the output to 0, there is an effect that unnecessary heating is not performed in a portion which is not required to be heated until the local heating means is controlled to stop.

The same effect is obtained if the electromagnetic wave emitting means is controlled to increase the output after the local heating means is controlled.

If the local heating means is controlled by the position detection means for detecting the position of the local heating means, the local heating means can be accurately controlled to the target position, and thus the effect of enabling the local heating to be performed with higher accuracy is obtained.

If the local heating means is controlled to a predetermined position at least at one of the time when heating is started and the time when heating is stopped, the local heating means is controlled to a target position with reference to the predetermined position when heating is performed next time.

Further, if the object to be heated in the heating chamber is discriminated by the object discrimination means, the low temperature portion in the object to be heated is discriminated by the low temperature portion discrimination means, and the distribution changing means is controlled, the food can be appropriately heated without performing unnecessary heating, and the waste of energy can be reduced.

If the low temperature portion discriminating means discriminates the low temperature portion from the heating range set by the heating range setting means and controls the distribution changing means, different kinds of food having different optimum temperatures can be simultaneously heated and cooked at the respective optimum temperatures.

Moreover, if the heating range is recorded in the recording storage means by the recording means and called out by the recording calling means, the operation is simple and convenient, and the user can use the heating range conveniently.

Further, if the heating target position switching unit is controlled to start from the time when at least one of the type of the object to be heated, the magnitude of the electromagnetic wave heating output, the heating start time, and the heating method is input by the 1 st operation button to the time when the heating start is input by the 2 nd operation button, the heating target position switching unit is already in a state where the heating target position can be heated at the time of starting the heating. Thus, the heating is not performed on the portion which is not required to be heated, and the heating is made uniform while suppressing the heating unevenness. Also, since the portion not required to be heated is not heated, the heating time can be shortened, and the waiting time of the user can be reduced. And because the part which does not need to be heated is not heated, the heating efficiency can be improved, and the power consumption is saved. Further, if the heating-site switching unit is controlled before the start of heating, the heating-site switching unit may not be controlled or the number of times of control may be reduced during heating. Therefore, the electric field can be prevented from being disturbed or the reflected wave can be prevented from being increased during the control of the heating portion switching portion, and abnormal heat generation of the electromagnetic wave emitting means can be prevented. Thereby improving the service life of the electromagnetic wave emission means. Similarly, the occurrence of harmonics can be prevented by suppressing the disturbance of the electric field or the increase of the reflected wave. Thus, noise can be suppressed, and malfunction of other parts and external devices in the high-frequency electric wave heating apparatus can be prevented.

If the hot spot can be changed according to the purpose of heating, the heating apparatus can operate in accordance with the demand for uniform heating of the object to be heated to some extent, or can concentrate the heating on a specific spot of the object to be heated. In the case of cooking in a microwave oven as a typical high-frequency electric wave heating apparatus, a single food can be heated without unevenness, or a plurality of kinds of foods can be selectively heated (for example, cooked and fried foods are heated on one dish, and lettuce is not heated).

If the drive section drives the local heating means at a constant cycle immediately after the start of heating and performs drive control for changing the cycle or stopping the cycle during heating, the heating distribution generated immediately after the start of heating and the heating distributions during and after heating can be changed. In particular, since a specific part of the object to be heated can be heated intensively after the heating is performed halfway, the part which is heated late can be heated, and the unevenness of heating occurring before the heating is performed halfway can be compensated to achieve the uniformity, or the part which is to be partially heated can be further heated.

The heating distribution generated immediately after the start of heating and the heating distributions after the middle of heating can be changed if the control unit controls the heating output of the electromagnetic wave emitting means to be a constant value after the start of heating and controls the heating output to be changed or the heating to be stopped depending on the state of the local heating means during the heating. In particular, since a specific part of the object to be heated can be prevented from being heated after the heating is performed, the part being heated can be prevented from being heated, unevenness in heating occurring before the heating is performed can be compensated for, and the heating can be made uniform, or further, only the part not to be heated can be prevented from being heated.

If electromagnetic waves are introduced into the heating chamber through the feeding chamber and the feeding port switching section is provided in the feeding chamber, the waveguide and the heating chamber are connected to the feeding chamber, and the electromagnetic wave reflection is easily suppressed and matching is easily performed. Further, in the case where the power supply port switching portion does not protrude into the power supply chamber, and particularly, the power supply port switching portion is covered to prevent the hand of the user from touching, the bottom surface of the heating chamber including the cover can be flattened, so that the user can easily clean the inside of the heating chamber. In addition, in the case of the cover of the local heating means, the cover is enough to cover the feeding chamber even if the cover is not sized to cover the entire bottom surface of the heating chamber, so that the cover can be made small and inexpensive.

If the turntable is made of metal or conductive material and a gap having a length of 1/2 or more of the wavelength of the electromagnetic wave exists in the rotation direction, the electromagnetic wave can penetrate up and down through the gap of the turntable. Therefore, the heating portion of the object to be heated can be easily switched.

If the turntable is made of metal or conductive material, the heat resistance is good, and the turntable can be used even in the case where a heating element is provided on the bottom surface of a heating chamber such as a general-purpose microwave oven with a grill function.

If the turntable is made of a material that is transparent to electromagnetic waves, the electromagnetic waves can penetrate through the turntable up and down without being reflected. Therefore, the heating portion of the object to be heated can be easily switched.

If there is an upward projecting inclined portion with a radius of R (R > R) around the rotation center of the turntable with a radius of R on the bottom surface of the heating chamber, when the liquid object to be heated is knocked over on or around the turntable, cleaning and other tasks can be performed without detaching the turntable, and the operation is convenient.

If the local heating means is controlled to heat the center of the object after the start of heating and then heat the periphery, there is an effect of preventing the edge portion of the object from being excessively heated. Thus, there is an effect of suppressing unevenness of heating. When the heating unevenness is small, unnecessary heating can be eliminated, and therefore, excellent heating efficiency and power saving can be achieved, the heating time can be shortened, and the waiting time for the user can be reduced.

If the direction of the electromagnetic wave is directed to the center of the bottom surface of the heating chamber after the start of heating by means of the local heating means, the center of the object to be heated is mainly heated, and then if the direction of the electromagnetic wave is directed to the outside of the bottom surface of the heating chamber, the periphery of the object to be heated is mainly heated, and therefore the degree of heating unevenness can be reduced.

If the power supply port switching unit is driven before partial overheating occurs on the object to be heated by the output of the detection unit for detecting the physical quantity of the object to be heated and the state in the heating chamber, the effect of switching the heating unit and suppressing overheating is obtained.

When thawing an object to be heated in a frozen state, electromagnetic waves are continuously radiated to the object to be heated in a range where the maximum temperature of the object is estimated to be 0 ℃ or lower to heat the object, and when the maximum temperature is estimated to exceed 0 ℃, the radiation of the electromagnetic waves is controlled to be temporarily stopped, whereby the spread of the temperature difference after the maximum temperature exceeds 0 ℃ can be suppressed, and the degree of temperature unevenness can be reduced by heat conduction in the object to be heated during the time of stopping. Therefore, thawing results with less heating unevenness can be provided.

If the local heating means is driven when the emission of electromagnetic waves is stopped or reduced, the electromagnetic waves in the heating chamber are not stirred during the driving. Since the electromagnetic wave emitting means can be used in a stable operating region, there is an effect of suppressing unnecessary radiation and temperature rise of the electromagnetic wave emitting means, and it is possible to make measures against noise and a cooling structure easier.

If the local heating means is constituted by a rotary waveguide, a rotary antenna or a stirrer, the direction of the electromagnetic wave can be easily switched with a simple structure and a driving method. Therefore, the price can be reduced, and the reliability is provided as seen from the past practical results.

If the drive unit for driving the local heating means is constituted by a stepping motor or a combination of a motor and a switch, the position of the local heating means can be accurately and easily controlled, and therefore the direction of the electromagnetic wave can be accurately and easily controlled. Therefore, the heating unit can be switched with a simple and inexpensive configuration and with higher accuracy.

If it is determined that the emission of electromagnetic waves is temporarily stopped based on the output of the detection means, the ratio of the heat conduction inside the object to be heated and the temperature increase due to the temperature difference between the object to be heated and the atmosphere in the heating chamber can be determined based on the state of the object to be heated or the inside of the heating chamber. Therefore, the heating can be appropriately performed to suppress unevenness in thawing of the object to be heated.

If a plurality of waveguides are arranged close to each other, a small amount of material can be formed in a small space. Therefore, the size, weight and price can be reduced.

If the waveguide branches at the node of the electric field, the electromagnetic wave is efficiently transmitted in the branched waveguide, and therefore, the electromagnetic wave can be efficiently transmitted into the heating chamber through the plurality of openings, and therefore, the heating efficiency is excellent. Therefore, the heating time is short, the waiting time of the user can be reduced, the excessive power consumption can be suppressed to the utmost, the energy can be saved, the loss of the electromagnetic wave emitting means can be reduced, and the reliability can be improved.

If the cross-sectional area of the branched waveguide is reduced, the waveguide can be formed with a small amount of material in a small space. Therefore, the size, weight and price can be reduced. Since the length of the branched waveguide is an integral multiple of 1/2 of the in-pipe wavelength g, which is greater than 0, the electromagnetic wave can resonate at the in-pipe wavelength g even in the branched waveguide. Therefore, the electromagnetic wave can be efficiently transmitted into the heating chamber through the plurality of openings, and the heating efficiency is good.

When the width of the branch point between the 1 st waveguide and the branched waveguide is set to 1/4 or less of the in-pipe wavelength g, the electromagnetic wave in the 1 st waveguide in the resonance state is transmitted to the branched waveguide with good efficiency while maintaining the resonance state. Since the electromagnetic wave is efficiently transmitted into the heating chamber through the plurality of openings, the heating efficiency is excellent.

If there are a plurality of openings, the shielding part contacts with the protruding part fixed on at least one of the heating chamber and the waveguide or the protruding part of the conductive member, and shields the openings, the electromagnetic wave can not be transmitted between the shielding part and the protruding part, and the openings are completely shielded. Therefore, the opening through which the electromagnetic wave enters and exits can be accurately switched, and the heating distribution can be freely changed, thereby achieving the optimal heating distribution according to the purpose. So that any food can be uniformly heated. Also, since the leakage of electromagnetic waves from between the shielding portion and the protruding portion is also suppressed, it is safe, and the problem of noise is solved, and it is possible to prevent the influence of the electromagnetic waves on an external device to cause malfunction.

If the sealing portion has a plurality of openings and is formed of a member fixed to at least one of the heating chamber and the waveguide, electromagnetic waves are not transmitted between the shielding portion and the openings, and leakage of electromagnetic waves to the outside is suppressed.

If one shielding part is used as a shielding plate for opening and closing a plurality of openings on the same wall surface, the structure of the shielding part can be simplified and the number of components can be reduced. Thus having the effect of reducing the price. If the shielding part is not moved due to an accident, any opening is always opened, and the electromagnetic wave can be always supplied into the heating chamber. Therefore, the opening is not completely shielded, the electromagnetic wave cannot enter the heating chamber, and the electromagnetic wave emitting means and the waveguide are not easily subjected to abnormal loss and heat generation, and are safe and highly reliable.

If the shielding part is driven by one driving part to shield or open a plurality of openings, the driving part has the advantages of simplified structure, reduced components and easy control. Therefore, the size, weight and price can be reduced.

When the shielding part is operated when the electromagnetic wave emission is stopped, the electric field is not scattered during the operation of the shielding part, and the abnormal loss of the electromagnetic wave emission means and the generation of higher harmonics can be prevented. Therefore, the problem of noise is solved, and the influence of the noise on external instruments can be prevented from causing misoperation.

If the position of the shielding part is set to a position suitable for heating a light object or for heating in a short time at the start of heating or at the stop of heating, a preparatory work for heating a light object or the like in a short time every time heating is started is already done. Therefore, the heating by putting the light-weight object to be heated does not fail. On the other hand, when a large number of objects to be heated are placed, which require a long time for heating, it is completely possible to move the shielding part to an appropriate position after the start of heating. As a result, according to the present invention, when a lightweight object to be heated is placed, an appropriate heating distribution can be given from the initial stage of heating. In addition, when the light-weight object to be heated is put in, the shielding part is not required to be driven to operate, so that the power consumption required for driving the shielding part to move and the loss in the process of the shielding part operation are avoided, the heating efficiency can be improved, and the time is shortened. Further, since the driving unit is controlled so that the position of the object to be heated is set to a position suitable for heating a light object to be heated or for heating for a short time at the time of starting or stopping heating, preparation for heating for a short time such as heating a light object to be heated every time heating is started is already made.

If the output of the detection means is not received or ignored in a short time after the start of heating, the detection means can be accurately detected in a stable state without fear of detection errors due to an unstable state of the electromagnetic wave at the initial stage of heating. Therefore, the control based on the output of the detection means is also accurate, and highly reliable operation can be realized. Similarly, it is not necessary to set the time when the electromagnetic wave is not emitted for the purpose of detecting the initial state of the object by the detection means at a time immediately after the start, and effective heating can be performed from the beginning. Therefore, the waiting time of the user can be shortened.

If the shielding part is operated a plurality of times from the start of heating to the stop of heating based on the output of the detection means, the heating distribution is changed accordingly, and appropriate heating corresponding to the state of the object to be heated can be performed. Therefore, uniform and effective heating can be performed for any object to be heated.

If the drive unit is controlled to change the position of the object a plurality of times during the period from the start of heating to the stop of heating by the detection means, the heating distribution changes accordingly, and thus appropriate heating can be performed in accordance with the state of the object. Therefore, any object to be heated can be uniformly and effectively heated.

If a structure having a driving object such as a rotating object provided in a waveguide and a plurality of openings is adopted, the openings from which electromagnetic waves are likely to be emitted and the openings from which electromagnetic waves are unlikely to be emitted are switched by the rotation of the rotating object, and apparently, various electric fields are switched successively so that the entire object to be heated can be uniformly heated.

If a driving object such as a rotating object is provided in the waveguide, the structure is simple and does not occupy space, and the effective volume of the inside of the heating chamber can be maintained with respect to the size of the entire apparatus.

If the driving object is configured to switch the plurality of operation modes in accordance with the input of the operation button, the heating can be performed while switching the optimal electric field distribution in accordance with the object to be heated and the overall heating program, as compared with the rotation at a constant speed, and thus more uniform heating can be performed.

On the other hand, when the electric field distribution is not required to be switched so well (for example, when a liquid such as milk is uniformly distributed by convection heating on the bottom surface), the rotating body may be stopped at the position where the adjustment is best. In this case, since the object to be heated can be heated efficiently, the heating time is short, and the waiting time for the user can be shortened. And the loss is reduced, and the electric power is saved. Also, the thermal stress on the electromagnetic wave emitting means is reduced, and the reliability is improved.

If the state of the object to be heated and the inside of the heating chamber are detected by the detection means and the rotating object is switched among a plurality of operation modes according to the detected state, the object to be heated can be heated while switching the most appropriate electric field distribution according to the state of the object to be heated, and thus the object can be heated more uniformly.

On the other hand, if the detection means determines that the distribution is not required to be switched as good as the electric field distribution (for example, a liquid such as milk that can be uniformly distributed by convection as long as it is heated on the bottom surface), the rotating body may be stopped at the position that is optimally adjusted thereafter. In this case, since the object to be heated can be heated efficiently, the heating time is short, and the waiting time for the user can be shortened. And also to reduce loss and save power. Also, the thermal stress on the electromagnetic wave emitting means is reduced, and the reliability is improved.

In the case of using frozen food (frozen food thawing), since the rotating object is rotated, the electric field in the heating chamber is constantly changed, and it is possible to prevent the electromagnetic wave from concentrating on a part of the frozen food. It is thus possible to make it less susceptible to global freezing but with only a portion in the thawing-specific distribution of being cooked.

If the object stage for placing food is not rotated by the operation of the operation button when milk or soup is placed, the adjustment state will not be changed by the rotation. In this case, if the adjustment is made, the heating can be performed with high efficiency. And because the rotating power of the rotary table is not needed, the power can be saved. In general, in the case of processing food such as milk or soup, the influence of the rotation or stop of the turntable on the distribution is small, and therefore, the distribution is not uneven.

If the detection means determines that the object to be heated is a liquid, the adjustment state is not changed by the rotation if the stage on which the food is placed is not rotated. In this case, if the adjustment is made, the heating can be performed with high efficiency. And because the rotating power of the rotary table is not needed, the power can be saved.

When electromagnetic waves are introduced into the heating chamber through the plurality of openings, an electric field distribution different for each opening can be generated, and the object to be heated can be heated more uniformly than in the case of one opening.

Further, if the opening is formed in the bottom surface of the heating chamber, it is possible to determine approximately whether or not the object to be heated can be heated strongly in which portion at the opening position, and it is easy to form a desired distribution. Also, if the opening is formed in the bottom surface of the heating chamber, the object to be heated is positioned close to the opening, and the heating efficiency is high. Therefore, the heating time is short, the waiting time of the user can be reduced, the excessive power consumption can be suppressed to the utmost, the energy can be saved, the loss of the electromagnetic wave emitting means can be reduced, and the reliability can be improved.

If the position of the object to be heated in the height direction is changed or the distance between the object to be heated and the conductive member under the bottom surface of the object to be heated is changed, the heating distribution of the object to be heated can be changed even if the electric field distribution in the heating chamber is the same, and the distribution can be freely controlled.

By switching the openings, the openings through which electromagnetic waves are easily emitted are switched among the plurality of openings in accordance with the input of the operation button and the output of the detection unit, so that a heating distribution corresponding to the operation content and the detection content is generated, and the heating distribution of the object to be heated can be made uniform.

When the object to be heated is a liquid by switching the openings, if an electromagnetic wave is emitted from the opening closest to the center of the bottom surface of the object to be heated among the plurality of openings, the center of the bottom surface of the object to be heated can be heated intensively to reach a higher temperature than other portions. In this case, since the object to be heated is a liquid, convection occurs, the temperature is naturally equalized in the vertical direction, and therefore, the upper portion does not overheat, which is a problem unique to the liquid object to be heated, and uniform heating distribution with no temperature difference between the upper and lower portions can be realized.

If the opening closest to the center of the bottom surface of the object is made less likely to emit electromagnetic waves when the height of the object is higher than a certain level or the weight is heavy by switching the openings, scorching and overheating of the lower part due to overheating of the bottom surface, which are problems specific to a large object, can be eliminated, and uniform heating distribution with no temperature difference between the upper and lower parts can be realized.

If the position of the object to be heated in the height direction is changed or the distance between the object to be heated and the member having conductivity under the bottom surface of the object to be heated is changed in accordance with the input of the operation button and the output change of the detection means, the heating distribution can be changed in accordance with the contents of the operation and the detection, and an optimum heating distribution according to the purpose can be obtained.

When the height of the object to be heated is lower than a certain level or the object is light in weight, if the position of the object to be heated in the height direction is increased or the distance between the object to be heated and the conductive member under the bottom surface of the object to be heated is increased, the problem of local concentration of the electric field which is peculiar to a small object to be heated can be solved, and uniform heating distribution can be realized.

If the sealing portion is movable in the sub-waveguide branched from the waveguide between the 1 st opening and the 2 nd opening among the plurality of openings, the opening for apparently easily transmitting the electromagnetic wave from the upper waveguide into the heating chamber can be switched by the movement of the sealing portion, and the heating distribution can be freely changed.

Similarly, the spark and the radio wave leakage do not occur when the opening portion is switched, and therefore, the switch is extremely safe.

If the opening through which electromagnetic waves are likely to enter the heating chamber from the waveguide is switched in accordance with the input of the operation button and the output of the detection unit by the movement of the sealing unit, a heating distribution corresponding to the operation content and the detection content can be generated, and the heating distribution of the object to be heated can be made uniform.

If the temperature and temperature change at a plurality of positions in the vertical direction of the object to be heated are detected by the 1 st temperature sensor and the temperature and temperature change at a plurality of positions in the horizontal direction of the object to be heated are detected by the 2 nd temperature sensor, the temperature distribution of the entire object to be heated can be detected with high accuracy.

If the temperature distribution of the object to be heated is detected by the temperature sensor, the position of the object to be heated in the height direction is changed, or the distance between the object to be heated and the conductive member under the bottom surface of the object to be heated is changed, and the electromagnetic waves are concentrated on a low temperature portion or are not concentrated on a high temperature portion, it is possible to suppress the unevenness of the heating distribution in accordance with the actual temperature of the object to be heated, and to realize extremely uniform heating.

If the temperature distribution of the object to be heated is detected by the temperature sensor, the openings are switched, and the openings from which electromagnetic waves are easily emitted are switched among the plurality of openings, so that the electromagnetic waves are concentrated on a low-temperature portion or not concentrated on a high-temperature portion, the unevenness of the heating distribution can be suppressed according to the actual temperature of the object to be heated, and extremely uniform heating can be realized.

If it is determined from the output of the temperature sensor that the degree of temperature increase in the low-temperature portion of the object to be heated is large or the degree of temperature increase in the high-temperature portion is small, that is, if temperature unevenness can be improved, the rotation of the stage on which the food is placed is stopped or decelerated, so that the heating distribution can be quickly improved, the distribution unevenness can be eliminated, and extremely uniform heating can be realized.

When it is determined from the output of the temperature sensor that the low temperature difference at a plurality of positions of the object exceeds a certain value, if the amount of air introduced into the heating chamber is increased by increasing the number of rotations of the air blower, increasing the air inlet, improving ventilation, or the like, the temperature of the entire periphery is averaged, and the temperature is averaged by the heat conduction in the object during this period, so that the uneven distribution can be eliminated and extremely uniform heating can be realized.

If the heating chamber and the waveguide are connected to each other through a plurality of openings and the 1 st opening is provided in the center of the bottom surface of the heating chamber (the center in the longitudinal direction and the center in the lateral direction), the center of the bottom surface of the object to be heated is heated through the 1 st opening and the edge of the object to be heated is heated through the other openings, so that the entire object can be uniformly heated.

If the structure is adopted such that all sides of the rectangular heating chamber bottom surface are parallel to the sides of the rectangular opening, a strong electric field in the opposite direction can be generated by the electromagnetic wave emitted by the electromagnetic wave emitting means with the opening interposed therebetween, and a target electric field distribution calculated with the heating chamber as a cavity resonator can be generated as a standing wave distribution on the heating chamber bottom surface. Therefore, the object to be heated can be given a desired heating distribution by using the wave mode in the heating chamber (at least in the vicinity of the opening) as a desired wave mode.

If at least one of the plurality of openings is shielded by the opening shielding portion, the distribution of the standing waves generated in the unshielded opening portion can be switched or various standing waves can be mixed, and therefore the heating distribution of the object to be heated can be switched or combined to be averaged.

If a plurality of openings are provided and the adjustment (output of a rated output value) is performed in a case where any of the openings is shielded, the object to be heated can be efficiently heated even if power is supplied to any of the openings. Therefore, the heating time can be shortened, and the waiting time of the user can be shortened. But also power can be saved. And the thermal stress on the electromagnetic wave emission means can be reduced, and the reliability is improved.

If the shielding part is rotated around the rotation axis at a position other than the center of the bottom surface of the heating chamber (the center in the vertical direction and the center in the horizontal direction) to shield the opening, the electric field distribution in the heating chamber can be stirred, and the heating distribution of the object to be heated can be made uniform. Similarly, since the opening can be provided in the center of the bottom surface of the heating chamber, the heating chamber can be switched between a simple configuration and heating and non-heating of the center of the bottom surface of the object to be heated, and thus more uniform heating can be achieved.

If the opening blocking portion rotates at a constant speed to block the opening portion, it can be realized by a driving portion rotating at a constant speed. Therefore, the electric field distribution in the heating chamber can be changed with a simple configuration (a configuration that is inexpensive and easy to manufacture), and the heating distribution of the object to be heated can be made uniform.

If the opening is covered by the disc-shaped opening covering portion, the opening covering portion can be formed without corners. Therefore, the electric field distribution in the heating chamber is changed with a simple structure (a structure that is inexpensive and easy to manufacture), and the heating distribution of the object to be heated can be made uniform. Similarly, since the opening shielding portion has no corner, there is little risk of damaging other members by contact, and the safety performance can be improved.

If the opening blocking portion is composed of an electromagnetic wave transmitting portion made of resin or the like and an electromagnetic wave blocking portion made of metal or the like, the state of transmission and blocking of electromagnetic waves can be changed by changing the position thereof with the driving portion. Therefore, the standing wave distribution in the heating chamber can be switched, various standing waves can be mixed, or the electric field distribution can be stirred, so that the heating distribution of the object to be heated can be made uniform. Similarly, the electromagnetic wave transmitting portion prevents electrical sparks between the opening and the electromagnetic wave shielding portion, thereby improving safety.

In the case where the opening area of the plurality of openings is the smallest at the closest opening area to the center of the bottom surface of the object, the electromagnetic wave coming out from the smallest opening can be made smaller than the electromagnetic wave coming out from the other openings. Therefore, the influence of the openings closest to the bottom surface of the heating chamber and the object to be heated, which have a much larger influence on the distribution than the other openings in the case of the same opening area, can be suppressed, and the influence of the other openings on the distribution can be increased, whereby the heating distribution of the object to be heated can be made more uniform.

If the shield is not provided for the opening other than the opening closest to the center of the bottom surface of the object to be heated (no rated output is provided), the electromagnetic wave emitted at this time can be made smaller than the electromagnetic wave emitted from the other openings. Therefore, the influence of the openings closest to the center of the bottom surface of the object to be heated, which have a larger influence on the distribution than the other openings in the same adjustment state, on the distribution can be suppressed, and the influence of the other openings on the distribution can be increased, so that the heating distribution of the object to be heated can be more uniform.

If the opening blocking section blocks the opening while moving at a speed that is not constant, the opening operation, the time required for the blocking operation, the time required for the opening operation, and the time required for the opening operation and the time required for the blocking operation can be changed for a certain opening. Therefore, the time required for the opening operation and the shielding operation, which are stable and difficult to establish the standing wave distribution without the electromagnetic wave entering the heating chamber, can be shortened, and the time required for the opening operation, which is stable and difficult to establish the standing wave distribution without the electromagnetic wave entering the heating chamber, and the time required for the shielding operation can be prolonged, whereby the object to be heated can be efficiently heated. Therefore, the heating time is shortened, and the waiting time of the user is reduced. The effect of saving electric power is also achieved. Also, the thermal stress of the electromagnetic wave emitting means can be reduced, and the reliability can be increased.

Industrial applicability

As described above, the high-frequency heating apparatus according to the present invention can heat an arbitrary portion of an object to be heated, and can equalize the heating distribution of the entire object to be heated by combining the heating of various portions, and therefore, is suitable for use as a microwave oven for heating and cooking various foods.

Claims

1. A high-frequency heating apparatus includes:

a heating chamber accommodating an object to be heated;

an electromagnetic wave emitting device that emits an electromagnetic wave;

2. The high-frequency heating apparatus according to claim 1, characterized in that said control means controls said local heating means after controlling said electromagnetic wave emitting means to reduce or eliminate the output.

3. The high-frequency heating apparatus according to claim 1, wherein said control means controls said electromagnetic wave emitting means to increase the output after controlling said local heating means.

4. The high-frequency heating apparatus according to claim 1, further comprising setting means for allowing a user to make a setting, characterized in that said control means controls said local heating means through said setting means.

5. The high-frequency heating apparatus according to claim 4, wherein the setting means has a first operation key for allowing a user to set at least one of a kind of an object to be heated, a heating output size, a heating time and a heating method, and a second operation key for setting a heating start, and wherein the control means controls the local heating means and the electromagnetic wave emitting means through the first operation key and the second operation key, respectively.

6. The high-frequency heating apparatus according to claim 1, wherein the control means controls the local heating means to switch the electromagnetic wave in a direction in which an object to be heated is placed or in a direction in which an object to be heated is not placed.

7. The high-frequency heating apparatus according to claim 1, wherein the control device controls the local heating device to switch heating of a central portion of a bottom surface of the object to be heated or heating of a substantially peripheral portion of the object to be heated.

8. The high-frequency heating apparatus according to claim 1, characterized in that the control means controls the local heating means to switch the portion to be heated of the object in two-dimensional or three-dimensional space.

9. The high-frequency heating apparatus according to claim 1, characterized in that said control means controls the emission direction of said electromagnetic wave along a spiral trajectory by said local heating means.

10. The high-frequency heating apparatus according to claim 1, wherein said control means has intermittent control means which intermittently controls said local heating means so as to concentrate the electromagnetic wave at a limited portion.

11. The high-frequency heating apparatus according to claim 1, wherein said control means has continuous control means which continuously controls said local heating means so as to radiate the electromagnetic wave uniformly to a large area.

12. The high-frequency heating apparatus according to claim 1, characterized in that the control means has: intermittent control means for intermittently controlling the local heating means so as to concentrate the electromagnetic waves at a limited portion; a continuous control means that continuously controls the local heating means so as to uniformly radiate electromagnetic waves to a large area; and a switching control device that switches between the intermittent control device and the continuous control device.

13. The high-frequency heating apparatus according to claim 1, wherein the control means controls the local heating means to a predetermined position at least at the start of heating or at the end of heating.

14. The high-frequency heating apparatus according to claim 13, wherein the predetermined position is a position suitable for the object to be lightweight or a position suitable for heating for a short time.

15. The high-frequency heating apparatus according to claim 1, further comprising a fan for supplying air to the heating chamber, wherein said control means controls an amount of air to be introduced into said heating chamber.