EP2938161A1 - Method and household appliance - Google Patents

Abstract

The present invention relates to a method for operating a household appliance 1 and a domestic appliance 1 with at least one heating device 12 for the dielectric heating of material 200 by electromagnetic radiation in at least one treatment space 3. At least one measuring system 4 with at least one processing device 5 is provided. The measuring system 4 is suitable and designed to generate electromagnetic measuring radiation. The measuring system 4 has at least one transmitting device 14 for at least temporarily transmitting electromagnetic measuring radiation into the treatment space 3 and at least one receiving device 24 for at least temporarily receiving the measuring radiation sent into the treatment space 3. The measuring system 4 is suitable and designed to detect at least one characteristic variable for a wave property of the received measuring radiation. The processing device 5 is suitable and designed to determine at least one measure of a spatial power distribution of the radiation that can be supplied by the heating device 12 into the treatment space 3 based on the change in the wave property of the received measurement radiation with respect to the transmitted measurement radiation.

Description

The present invention relates to a method for operating a household appliance and a domestic appliance with at least one heating device for the dielectric heating of material to be treated by electromagnetic radiation in at least one treatment room. In this case, at least one measuring system with at least one processing device is provided.

When using microwave radiation in domestic appliances for heating up the treated material, electromagnetic resonances generally form in the treatment room. The resonances can be described as vibration modes with a spatial distribution of field strength fluctuations with maximum amplitude, so-called bellies, and field strength fluctuations with minimal amplitude, so-called nodes.

The common modes of treatment room and material to be treated essentially correspond to an electromagnetic field distribution whose appearance describes the possible spatial power input into the material to be treated. The microwave power is thus distributed unevenly due to the resonance modes. Thus, for example, there are places in a cooking space where the food to be cooked is located in the area of a knot and is hardly heated, and places where the food to be cooked is in the area of a stomach and thus is heated particularly strongly.

In the prior art, various approaches have become known to make the heating of the food spatially uniform. For example, the food is moved with a turntable through the existing modes. In this case, the resonance modes are changed by the change in position of the food. Another possibility for uniform distribution of radiant power in the cooking chamber offer so-called. Stirrer or impellers. Typically, a Stirrer is an electrically conductive sheet metal part, which is rotated by a motor and is positioned at the transition from the shaft channel to the cooking chamber. The Stirrer influences the wave distribution and thus also the distribution of the modes in the cooking chamber.

As a rule, the known approaches make the heating of the cooking product more uniform, so that an averaging of the power input takes place over time. Either the food to be cooked is moved through the areas of the modes over time or the modes themselves are changed in chronological succession. The problem with such methods, however, is that the actual resonances and field strengths in the treatment room are generally unknown are. This results in a temporal overlay or change of modes, but not all modes occur or must be evenly distributed. This can lead to a performance distribution that is not optimal in terms of uniformity.

It is therefore the object of the present invention to provide a method for operating a household appliance, whereby a more uniform distribution of the radiation power in the treatment room is made possible.

This object is achieved by a method having the features of claim 1 and a domestic appliance having the features of claim 12. Preferred features are the subject of the dependent claims. Further advantages and features will become apparent from the general description of the invention and the description of the embodiments.

The inventive method is suitable for operating a household appliance. At least one heating device is provided for the dielectric heating of material to be treated by electromagnetic radiation in at least one treatment space. At least one measuring system generates at least temporarily electromagnetic measuring radiation. The measuring system sends the measuring radiation at least temporarily with at least one transmitting device in the treatment room. At least temporarily, the measuring radiation sent into the treatment room is received again by at least one receiving device of the measuring system. The measuring system detects at least one characteristic variable for a wave property of the received measuring radiation. At least one measure of a spatial power distribution of the radiation that can be fed from the heating device into the treatment space is determined with at least one processing device on the basis of the change in the wave property of the received measuring radiation with respect to the transmitted measuring radiation.

The method according to the invention has many advantages. A considerable advantage is that a measuring system is provided, with which a measure of a spatial power distribution of the radiation that can be fed from the heating device into the treatment space is determined. As a result, the distribution of the radiation power in the treatment room and in the material to be treated can be determined particularly reliably. On the basis of this measure can be determined, for example, where in the treatment room nodes and bellies occur and how the resonance modes are spatially distributed. Also, a changed distribution of the resonances, for example by introduced treated, can be detected. This information can be used particularly advantageously, for. B. to achieve a very uniform heating of food and to control the heater optimally, since the actual existing modes are taken into account.

The detected by the measuring system size preferably describes a wave property such. As phase, amplitude, frequency, wavelength and / or polarization. Also possible are other common in high-frequency technology or radar magnitudes for the detection of signals. The quantity detected by the measuring system is determined in particular as a function of the frequency and / or as a function of time.

The change of the received measuring radiation in relation to the transmitted measuring radiation is preferably determined by the change of at least one of the at least one variable detected by the measuring system. The change relates in particular to the phase and / or the amplitude of the measuring radiation. However, it is also possible that the change in the received measuring radiation with respect to the transmitted measuring radiation relates to the frequency and / or the wavelength and / or the polarization and / or the angle of rotation or at least one other common size of the high-frequency technology. The change is preferably detected and / or described by at least one scatter parameter or S parameter. In particular, the radiation power absorbed by the material to be treated and / or the corresponding scattering parameter is taken into account as a function of the frequency.

The item to be treated is preferably an object which is introduced into the treatment room essentially for treatment. This can be, for example, an object to be cleaned and / or dried and / or a food or an object to be heated. It is also possible that the material to be treated is also introduced into the treatment room and / or only to determine the spatial power distribution.

Material to be treated in the sense of this application can also be any object in the treatment room which, in particular, has been introduced into the treatment room together with the object to be treated, in particular as an alternative. As a cooking vessel, a laundry bag or a solvent or the like. It is possible that the spatial power distribution is determined together with the auxiliary material to be treated and / or separately from the auxiliary material to be introduced.

In an advantageous embodiment, it is preferred that the spatial power distribution is determined after the introduction of the material to be treated into the treatment room. This has the advantage that a change in the spatial power distribution caused by the material to be treated is recognized. The determination can also be made repeatedly and / or regularly after the introduction of the material to be treated. Preferably, the spatial power distribution within the material to be treated is determined and taken into account. Particularly preferably, the determination takes place during the treatment process. In this case, the heating device can be set in a sleep mode, in which substantially no radiant power is sent to heat the material to be treated. However, the measuring system and the heating device can also be operated in parallel at least temporarily.

The measure of the spatial power distribution of the radiation to be supplied into the treatment room without material to be treated is preferably determined before the introduction of the material to be treated. This can already be done in the factory. In this case, the measured values can be stored, for example, in a memory device as reference values. It is also possible that the values are recorded when the device is switched on by a user for the treatment of items to be treated or when a specific operating mode and / or a specific program mode is selected. It is also possible that a service mode is activated, in which a determination of the spatial power distribution is performed.

Preferably, the determined power distribution describes at least one mode for the electromagnetic field distribution in the treatment room. The determined power distribution can also describe at least one electromagnetic resonance or cavity resonance of the deliverable radiation in the treatment room. In particular, the mode describes a distribution of field strength fluctuations with maximum amplitude, so-called bellies, and field strength fluctuations with minimal amplitude, so-called nodes. The determined spatial power distribution preferably describes at which position electromagnetic resonance resonances are present in the treatment space and / or such a node or abdomen is located.

This has the advantage that field strength fluctuations in the treatment room or in the material to be treated can be detected and localized. In addition, it can be used to determine frequencies at which the material to be treated can absorb a great deal and / or a particularly low level of electromagnetic radiation power. Thus, the heater can be controlled accordingly to achieve optimum heating of the material to be treated. For example, the expected duration of treatment can be calculated and the heater can be controlled accordingly. The material to be treated can also be aligned according to the distribution of power in the treatment room.

In a further embodiment of the method, the material to be treated is aligned in the treatment space as a function of the determined power distribution by at least one positioning device. The orientation can be changed over time, so that different residence times of the material to be treated in certain field strength zones are possible. It is also possible that the power distribution is determined repeatedly and the alignment is adjusted repeatedly. For example, the material to be treated can be aligned such that essential areas are positioned in nodes and / or bellies of the cavity resonance. It is also possible to change the positioning over time, so that a certain average power supply can be achieved. As a result, the power supply can be made very uniform, z. B. to heat a food gently. The positioning device may comprise at least one motor-driven rotary and / or pivoting device, such as. B. a turntable.

It is also possible that the heating device has at least one adjustable transmission device for the directed introduction of the electromagnetic radiation into the treatment space. In this case, the transmission device is set in particular as a function of the determined power distribution. For example, the transmission device can be set so that a cavity resonance is present in the treatment room, which has nodes or bellies in desired areas of the material to be treated. The transfer device can be adjusted over time in order to expose the material to be treated to different field strengths and to achieve a certain power input over time. The adjustable transmission device comprises z. B. at least one Stirrer or a rotating antenna. The transmission device may also include a transmitting antenna.

The transmission device and / or the positioning device are preferably set by a control device. In this case, the control device is in particular operatively connected to the measuring system and takes into account the determined values.

It is preferred that the power of the electromagnetic radiation sent by the heating device is adjusted as a function of the determined power distribution by at least one control device. In particular, the level of the supplied power and / or the duration of the power supply is set. For example, the average power output is set over a certain period of time. In particular, a clocked power output of the heating device is provided. It is also possible to set a number of heating devices and / or thermal heat sources. The heating device is designed in particular as a microwave heating device.

Preferably, the measuring radiation comprises at least two frequencies differing by at least 100 MHz between 10 megahertz and 1 terahertz. Preferably, a plurality and in particular a plurality of different frequencies are provided. In this case, it is also possible to provide frequencies and / or frequency intervals which adjoin one another and / or overlap at least partially.

The measuring radiation may have a frequency width of at least 10% of the center frequency of the frequency band used. Also possible is a frequency width of at least 10% of the arithmetic mean of lower and upper limit frequency of the frequency band used. A frequency width of at least 20% of the corresponding arithmetic mean value is preferred. In particular, the frequency width comprises at least 250 megahertz and preferably at least 500 megahertz and / or at least one gigahertz and / or at least 5 gigahertz, and more preferably more than 10 gigahertz. Also possible are 20 gigahertz or more.

The frequencies are preferably in a frequency band with a bandwidth that is wider than the ISM band of a conventional Mikrowellengargerätes (about 2.4 GHz - 2.5 GHz). Also possible are several bands. In particular, at least two bands are provided, the center frequencies of which have a spacing of at least one gigahertz and in particular at least five gigahertz and preferably ten or more gigahertz.

Preferably, the spatial power distribution is determined for at least two frequencies. The spatial power distribution can also be determined as a function of the frequency. The power distribution is determined in particular at frequencies which lie in a comparable frequency range as the radiation emitted by the heating device. This has the advantage that, for example, the cavity resonances determined at least approximately correspond to the cavity resonances in the heating mode.

It is possible for the heating device to emit electromagnetic radiation in an at least partially adjustable frequency range. In this case, the frequency range of the heating device can be set as a function of the determined spatial power distribution for at least one frequency by at least one control device. By adjusting the frequency certain resonances cavities can be realized, so that, for example, a particularly uniform heating of the material to be treated is possible.

But it can also be a targeted uneven heating can be achieved, for. B. warmer in the lower area than in an upper area. It can be adjusted over time, different frequencies, for example, over a desired treatment period to get a certain average power input into the material to be treated. The residence time at a certain frequency is described in particular by a weighted sum. The heating device may comprise at least one high-frequency oscillator and / or at least one high-frequency amplifier.

Preferably, based on the determined spatial power distribution at least one frequency is determined at which the material to be treated in the treatment room has a certain power consumption. In particular, the material to be treated has the highest possible power consumption. The emitted frequencies of the heating device are preferably adjusted on the basis of the determined frequency.

It is possible and preferred for the determined power distribution to be matched with at least one reference parameter stored in at least one memory device. there In particular, the power supply to the item to be treated is adjusted as a function of the adjustment. For example, it is set at which cavity resonances in the treatment room power is emitted and / or how long radiation power is emitted in a cavity resonance.

The start of the cavity resonances is done as described above and z. B. by adjusting the positioning or the transmission device or the transmission frequency of the heater. The reference parameters may have been determined, for example, by simulations and / or measurements in advance or work. Regulations can also be stored in the memory device, which specify to the control device how the heating device and / or the positioning device and / or the transmission device are to be set as a function of the determined power distribution.

The domestic appliance according to the invention comprises at least one heating device for the dielectric heating of material to be treated by electromagnetic radiation in at least one treatment space. In this case, at least one measuring system with at least one processing device is provided. The measuring system is suitable and designed to generate electromagnetic measuring radiation. The measuring system has at least one transmitting device for at least temporarily transmitting electromagnetic measuring radiation into the treatment space and at least one receiving device for at least temporarily receiving the measuring radiation transmitted into the treatment space. The measuring system is suitable and designed to detect at least one characteristic variable for a wave property of the received measuring radiation. The processing device is suitable and designed to determine at least one measure of a spatial power distribution of the radiation that can be fed from the heating device into the treatment space based on the change in the wave property of the received measurement radiation with respect to the transmitted measurement radiation.

The domestic appliance according to the invention has many advantages. A significant advantage is that a measuring system is provided for determining the spatial power distribution. With such a measuring system z. B. cavity resonances in the treatment room can be determined, which occur during operation of the heater. With knowledge of the cavity resonances, the material to be treated can then be exposed to specific field strengths, for example. For example, food can be positioned so that it is particularly uniform or targeted unevenly heated.

In particular, at least one positioning device is provided. The positioning device is preferably suitable and designed to align the material to be treated in dependence on the determined power distribution in the treatment room. It is also possible that the heater at least one adjustable transmission device for directed Incorporation of the electromagnetic radiation in the treatment room. In this case, the transmission device is particularly suitable and designed to be set as a function of the determined power distribution by at least one control device. The positioning device and / or the transmission device are preferably designed as described above for the method.

The heating device is in particular suitable and designed to emit electromagnetic radiation power in a frequency range that can be set as a function of the determined power distribution. Preferably, the frequency range is adjustable by at least one control device. The heating device preferably comprises at least one oscillator device for generating radiation power with a specific frequency. Preferably, at least one amplifier device is provided for amplifying the radiation power of the oscillator device.

Preferably, the transmitting device and / or the receiving device are at least partially adapted and adapted to process measuring radiation at least two different frequencies between 10 megahertz and 100 gigahertz in a frequency bandwidth of at least 10% of the center frequency of the frequency band used. Particularly preferably, the transmitting device and / or the receiving device are designed and suitable for transmitting or receiving ultra-wideband signals. The processing device is preferably designed for evaluating ultrabroadbandiger signals.

It is also preferred that the transmitting device is at least partially designed and suitable to emit measuring radiation as at least one pulse at least temporarily and in particular repeatedly. In particular, the pulse duration is shorter than a nanosecond. The pulse duration is preferably in the range of one hundred or less picoseconds.

Particularly preferably, the measuring system comprises at least one ultra-wideband radar device and / or is designed as such. The ultra-wideband radar device is preferably adapted and configured to transmit and receive ultra-wideband signals. In this case, in particular, an ultrashort pulse can be emitted which comprises the widest possible frequency spectrum in accordance with a corresponding Fourier transformation. The frequency width in particular comprises at least 250 megahertz and preferably at least 500 megahertz and / or at least one gigahertz and / or at least 5 gigahertz, and more preferably more than 10 gigahertz. With such an ultra-wideband radar device radar information can be generated and evaluated, so that very well resolved spectral information is obtained. This allows the temperature of the material to be treated be determined accordingly. The individual temperature ranges can also be displayed spatially resolved.

Further advantages and features of the invention will become apparent from the embodiments, which will be explained below with reference to the accompanying figures.

Figur 1

eine stark schematisierte Darstellung eines Hausgeräts in einer perspektivischen Ansicht;

Figur 2

eine stark schematisierte Darstellung eines Hausgeräts mit einem Messsystem in einer geschnittenen Seitenansicht;

Figur 3

ein weiteres Hausgerät mit einem Messsystem in einer geschnittenen Seitenansicht;

Figur 4

ein anderes Hausgerät mit einem Messsystem in einer geschnittenen Seitenansicht;

Figur 5

noch ein weiteres Hausgerät mit einem Messsystem in einer geschnittenen Seitenansicht;

Figur 6

eine weitere Ausgestaltung eines Hausgeräts mit einem Messsystem in einer geschnittenen Seitenansicht; und

Fig. 7

noch eine weitere Ausgestaltung eines Hausgeräts mit einem Messsystem in einer geschnittenen Seitenansicht.

In the figures show:

FIG. 1

a highly schematic representation of a household appliance in a perspective view;

FIG. 2

a highly schematic representation of a domestic appliance with a measuring system in a sectional side view;

FIG. 3

another household appliance with a measuring system in a sectional side view;

FIG. 4

another home appliance with a measuring system in a sectional side view;

FIG. 5

yet another home appliance with a measuring system in a sectional side view;

FIG. 6

a further embodiment of a domestic appliance with a measuring system in a sectional side view; and

Fig. 7

Yet another embodiment of a household appliance with a measuring system in a sectional side view.

The FIG. 1 shows a domestic appliance 1, which is designed here as a cooking appliance 100. The cooking appliance 100 has a treatment chamber 3 designed as a cooking chamber 13. For the treatment of the material to be treated 200, a treatment device 2 is provided. The treatment device 2 comprises a thermal heating source 103 and a heating device 12.

The heater 12 is provided for the dielectric heating of the material to be treated 200 and formed here as a Mikrowellenheizquelle. The cooking chamber 13 is closed by a door 104. In this case, a safety device, not shown here is provided, which prevents operation of the heater 12 with the door open, so that leakage of microwave radiation is counteracted. For heating the cooking chamber 104 further heating sources, such as a Oberhitzeheizkörper and a lower heat radiator or a Dampfheizquelle or the like may be provided.

The cooking appliance 100 can be operated via an operating device 6. In this case, for example, the temperature in the cooking chamber 13 can be adjusted during the treatment process. Preferably, various other program modes and automatic functions may also be set. Also possible is an operation via a touch-sensitive surface or via a touchscreen or remotely via a computer, a smartphone or the like.

Furthermore, the domestic appliance 1 has a measuring system 4 shown here in highly schematic form. The measuring system 4 is provided for non-contact determination of various characteristic parameters of the material to be treated 200. In this case, the treatment device 2 is controlled as a function of the determined parameters. A parameter may be, for example, the internal temperature of the material to be treated 200. The measuring system 4 can, for. B. also determine the distribution of resonance modes at certain frequencies in the treatment room.

The measuring system 4 comprises a transmitting device 14, a receiving device 24, a processing device 5 and a memory device 7. The transmitting device 14 is suitable and designed to generate electromagnetic measuring radiation and to transmit it to the treatment chamber. In this case, at least part of the measuring radiation interacts with the material 200, which is not shown here, and is reflected by it again. The reflected measuring radiation is received by the receiving device 24.

In this case, at least one characteristic variable for a wave property of the received measuring radiation is detected by the measuring system 4. For example, the amplitude, frequency, phase or polarization or rotation angle is detected as a wave property. The processing device 5 then determines from the change of the wave property of the received measurement radiation with respect to the transmitted measurement radiation the characteristic characteristics of the processed material 200. The respective wave properties of the emitted measurement radiation may be stored as corresponding reference values in the processing device 5 or detected by the measurement system 4 during emission be.

The determined parameters are taken into account in the treatment of the material to be treated 200. In this case, the treatment device 2 is controlled as a function of the determined parameters. Preferably, the treatment device 2 is operatively connected to the measuring system 4. It is possible that further control devices not shown here are provided. For example, the temperature in the interior of the item to be treated 200 can be determined as a parameter. Depending on this temperature, the heating power of the thermal heat source 103 can then be adjusted accordingly.

If the material to be treated 200 is, for example, a roast piece, the heat output of the heating source 103 is regulated so that optimal temperature conditions for cooking the roast piece prevail in the cooking space 13. In the control of the treatment process, taking into account the determined parameters, also predetermined by the user target parameters can be considered. In the example of the roast piece, the user z. B. pretend that he wants a very crispy roast crust. In this case, the temperature of the thermal heating source 103 is up-regulated or switched on a Grillheizquelle when the measuring system 4 detects a temperature inside the roast piece, which corresponds to a Fertiggarpunkt.

In the FIG. 2 a household appliance 1 is shown in a highly schematic, sectional side view. The domestic appliance 1 here is a cooking device 100 with a treatment chamber 3 designed as a cooking chamber 13. The treatment device 2 comprises a thermal heating source 103 whose power is regulated by a control device 42. The control device 42 is also operatively connected to the measuring system 4. The measuring system 4 is designed as a reflectometer device 54, which is designed as a single-lens reflectometer. In this case, the transmitting device 14 and the receiving device 24 are housed together in a reflectometer, which thus also serves as a transmitter and receiver.

The Refleometereinrichtung 54 is also formed here as a broadband radar reflectometer. For this purpose, electromagnetic measuring radiation is generated and transmitted, which is preferably in a frequency band which is at least 10 gigahertz wide. For example, the frequency band here is 15 gigahertz or 20 gigahertz or more wide. In this case, the measuring radiation comprises at least two frequencies and preferably a plurality of frequencies. At least two of the frequencies differ by at least 100 gigahertz or more. Preferably, the measuring radiation may also have a frequency width of 10% or more of the center frequency of the frequency band used.

The measuring radiation is sent by the transmitting device 14 into the treatment space 3. In the treatment room 3, the measuring radiation inter alia interacts with the material to be treated 200 and is reflected by this. The reflected measuring radiation is detected by the receiving device 24. Here, two independent sizes are measured here, z. B. Amount and phase. The processing device 5 determines, based on the detected quantities, the frequency dependence of the ratio of radiation power transmitted into the treatment space 3 to reflected radiation power. The measured variables can be designated, for example, with the scattering parameter S11, as are also known in vector network analyzers.

The processing means 5 calculates from the measured, frequency-dependent scattering parameter S11 (as complex numbers, containing two independent measurands) for each Measurement frequency, first, the real part components and the imaginary part components of the complex permittivity epsilon. The complex S11 can be converted into complex epsilon. The permittivity describes the properties of the material in interaction with the measuring radiation for the material 200 to which the measuring radiation was reflected. This interaction is dependent, inter alia, on the temperature of the material 200 to be treated, which can advantageously be used to determine the temperature.

In order to determine the temperature of the material to be treated 200, the real part and the imaginary part of the complex permittivity are computationally viewed by the processing device 5 in a Cole-Cole diagram. As a result, a circular arc with a center point on the axis for the real part is writable. The temperature of the material to be treated 200 results from the circle radius or the position of the circle center on the real part axis.

Subsequently, the values for circle radius or circle center are compared by the processing device 5 with corresponding reference values which are stored in the storage device 7 of the measuring system 4. The reference value is, for example, a value for the radius of the circular arc or the position of the circle center on the real part axis of a known substance at defined temperatures. Also possible are reference values, which have been obtained by measuring defined treatment goods or by appropriate simulations. If, for example, the item to be treated 200 is a food, reference values for water or water-containing objects, based on the typical water content of foods, provide comparable results for the temperature determination.

For the determination of the circle radius or the center of the circle, it is advantageous that the corresponding measuring points for the permittivity are as far as possible on the circle radius. The methods presented here and the household appliances are particularly advantageous because a broadband radar reflectometer or ultra-wideband radars are used. The broadband measuring radiation used in this case allows the corresponding measuring points for the permittivity to be far apart in terms of frequency, so that a corresponding accuracy and reliability of the temperature determination is possible.

Another advantage of the broadband measuring radiation is that correspondingly few measuring points are sufficient for a reliable temperature determination. In the case of broadband measuring radiation, the measuring points on the circle radius are so far removed that a reliable construction of the center of the circle z. B. by secant formation and establishment of the perpendicular bisector is possible. The center of the circle lies at the intersection of the mid-perpendiculars on the secant. The center of the circle can also result from the average of the intersections of all mid-perpendiculars on the secants with the axis for the real part of the permittivity. In this case, the additional information is used that the center point on the real part axis must lie. It is also possible to fit a circle into all existing measuring points for the permittivity or to calculate them approximately. The center or circle radius is then calculated from this circle.

Due to the broadband measuring radiation measuring points can be detected, which are so far apart on the circle radius, that the secants are as long as possible. Such methods have the advantage that it is not necessary to scan the entire frequency band for imaging the semicircle, but only a few measuring points from which the circle can subsequently be calculated. For example, for water to image a complete semicircle at 0 ° C, a frequency band of about 1000 gigahertz is required. However, measurements in such a wide frequency band require a very high technical effort. The previously presented method allows a considerably less expensive temperature determination, since a narrower band with less frequencies to be scanned can be used.

For example, a reliable temperature determination of water or aqueous products 200 by means of measured values from a frequency band of only 10 gigahertz is possible. Depending on the required accuracy and a lower or a higher frequency width are possible. Therefore, the method requires only a correspondingly low technical complexity, so that an application in commercial household appliances is economically possible. Another advantage of viewing in a Cole-Cole diagram is that it is relatively safe to deduce the circle from a comparatively small pitch circle segment because it is known that it is a circle, not an ellipse or even a circle more indefinite function course.

The reflectometer device 54 may also be formed as a two-port or multi-port reflectometer device 54. For this purpose, further transmitting devices 14 or receiving devices 24 can be provided. For example, the principle of transmission measurement is also possible. This can be particularly advantageous in certain geometric conditions in the treatment space 3. In addition to the reflection on the material to be treated 200, the transmission through the material to be treated 200 is also accessible to the measurement. Thus, in addition to the scattering parameters S11, the scattering parameters S12, S21 and S22 can also be determined. For this purpose, two or more reflectometer antennas can be provided. For more than two antennas, a variant is to operate them in pairs and to determine reflection and transmission for each pair.

The domestic appliance 1 shown here can also be designed as an alternative to the reflectometer device 54 with an ultra-wideband radar device 44, as described, for example, in US Pat. B. in the Fig. 3 is described.

It may be necessary for the measurement to be discriminated against other reflections, e.g. B. on the walls of the treatment room. In this case, no continuous wave train is used in the time domain, but only a very short pulse is emitted. This can be done by actually generating a pulse directly or by forming the required pulse by scanning a suitable frequency spectrum according to Fourier transform. In order to take into account only the reflection on the material 200 of interest, the transmitting device 24 is opened only for a specific time window. It is also possible that the processing device 5 only takes into account measurement radiation from a specific time window. The time window preferably comprises only the duration of the reflex of the material to be treated 200. In this case, the receiving device 24 or the processing device 5 is synchronized with the transmitting device 14 for generating the pulse.

Such a method and the household appliance 1 designed for such a method enable a very reliable and non-contact temperature determination of the item to be treated 200. A particular advantage is that the temperature inside an object or item 200 can be measured without contact. With knowledge of the internal temperature or the volume temperature, the treatment process and the treatment device 2 can be influenced in a particularly targeted manner. By way of example, the heating source 103 is controlled such that an optimum temperature for the respective treatment is present in the item to be treated 200. A particular advantage is that the volume temperature usually correlates very closely with the required cooking time of a food. This allows a very reliable control of automatic functions.

The FIG. 3 time a domestic appliance 1 in a highly schematic side view. The domestic appliance 1 is designed here as a cooking appliance 100. The treatment chamber 3 is a cooking chamber 13 and can be heated by a treatment device 2 designed as a thermal heating source 103. The heating source 103 is operatively connected to a control device 42 and can be regulated by this. The measuring system 4 is provided for determining characteristic characteristics of the material to be treated 200 and is designed as an ultra-wideband radar device 44.

The ultra-wideband radar device 44 here has two opposing antennas 440, 441. In this case, an antenna in each case comprises a transmitting device 14, 140 and a receiving device 24, 240. As a result, the antenna 440, 441 work as a transmitter and receiver. The bandwidth of the radar is here preferably greater than 250 megahertz, and preferably greater than 10% of the center frequency of the frequency band used. Particularly preferred is a frequency band which is released for such ultra-wideband applications. A particularly preferred frequency range is, for example, from 100 megahertz to 30 gigahertz or even 100 gigahertz.

The measuring system 4 generates measuring radiation and sends it out to the treatment room 3 and to the material 200 to be treated. In this case, a part of the measuring radiation is reflected by the material to be treated 200 and runs back to the antenna 440, 441, from which the measuring radiation was emitted. Another part of the measuring radiation is transmitted from the material to be treated 200 and transmitted to the opposite antenna 440, 441. Thus, it is possible to detect measurement radiation reflected and transmitted by the item to be treated 200. The measuring system 4 detects at least one characteristic variable for a wave property of the received measuring radiation, such. As the amplitude, frequency, phase or polarization or angle of rotation. Based on the change in the wave property of the received measuring radiation in relation to the transmitted measuring radiation, the characteristic characteristic of the material to be treated 200 is determined. The change relates in particular to the phase and / or the amplitude and / or further characteristic parameters and can be described for example by corresponding scattering parameters.

The processing device 5 calculates the real part and the imaginary part of the complex permittivity from the detected wave properties. In this case, the processing device 5 takes into account the frequency of the transmitted or received measuring radiation so that the complex permittivity or its real part or imaginary part can be determined as a function of the respective frequency or as a function of the frequency. On the basis of the complex permittivity and its frequency dependence, a wide variety of characteristic parameters for the item to be treated 200 can be calculated by the processing unit 5.

For example, the outer contour of the item to be treated 200, the temperature distribution or the moisture distribution in the interior of the item to be treated 200, the material composition, the density distribution and numerous other properties of the item to be treated 200 which can interact with electromagnetic measuring radiation can be represented. In this case, a wide variety of parameters can be spatially resolved or can be determined or represented integrated over the volume of the material 200 to be treated. So z. B. from the integral moisture content in the material to be treated 200 over the treatment time of the moisture loss of the treated 200 and thus z. B. the cooking process can be determined.

The transmission devices 14, 140 of the ultra-wideband radar device 44 are designed here for emitting ultrashort pulses. For example, the duration of the pulses is in the picosecond range. The pulses have correspondingly steep flanks. Thus, in the frequency representation, a correspondingly large bandwidth of typically a few GHz and z. B. 10 or 20 GHz or more. The receiving devices 24, 240 are designed to receive the broadband pulses. In this case, the receiving devices 24, 240 detect only the measuring radiation, which lies within a certain time window. The time window begins in an adjustable time after the transmission of the transmission pulse. Such a time window makes it possible to determine from which spatial area of the treatment space 3 or the material 200 the received measurement signal originates.

The momentum is influenced by the interaction with the item to be treated 200 so that characteristic wave sizes such as the phase or amplitude change. The changes are detected by the measuring system 4 and evaluated by the processing device 5 time-dependent, so that the electrical properties of the material to be treated can be determined in exactly the spatial area from which the received measuring radiation originates. Depending on the frequency bandwidth of the measuring radiation used, the spatial resolution is greater or smaller. If, for example, the spatial resolution is to be less detailed, one can work with a lower frequency bandwidth or the spatial information is averaged.

The FIG. 4 shows a highly schematic representation of another household appliance in a side view. The measuring system here has an ultra-wideband radar device 44, which has pivotable transmitting device 14 and a pivotable receiving device 24. By pivoting, a spatially resolved description of characteristic parameters of the material to be treated 200 is made possible with only one transmitting device 14 and one receiving device 24.

In this case, the receiving device 24 is preferably pivoted in a spacing grid along the material 200 to be treated. In this case, the transmitting device 14 retains its position. At each pivot position of the receiving device 24 measuring radiation is detected over the entire frequency band observed. In this case, the receiving device 24 has a time window for the reception of the measuring radiation reflected and transmitted on the material to be treated, which is preferably passed through once completely. Subsequently, the transmitting device 14 is moved, wherein at this new position, the receiving device 24 is pivoted again along the spacing grid.

It is also possible that a directional characteristic is used, so that the transmitting device 14 is pivoted when the receiving device 24 receives a signal with a corresponding phase shift. The measurement run described above can also be repeated in a desired time grid in order to observe the temporal behavior of the parameter of the material to be treated 200.

The FIG. 5 shows a further embodiment of a measuring system 4 with an ultra-wideband radar device 44. In contrast to that in the FIG. 4 The measuring system presented here is equipped with movable receiving devices 24, 240. The transmitting device 14 is pivotable. During a measuring operation, the transmitting device 14 assumes a specific pivot position while the Receiving devices 24, 240 are moved along the Behandlungsguts 200. Preferably, the receiving devices 24, 240 are moved along a predetermined distance grid. Other combinations of stationary, movable and / or pivotable transmitting devices 14 or receiving devices are also possible.

In the FIG. 6 a household appliance 1 with a measuring system 4 is shown, which allows a determination of the distribution of the radiation power in the treatment room 3. Cavity resonances are determined frequency-dependent, for example. The treatment room is designed as a cooking chamber 13. For heating the cooking chamber 13, the electric heater 12 is provided. The heating device 12 has an oscillator device 52 and an amplifier device 62, which together generate and amplify electromagnetic radiation power for heating the cooking chamber 13. The heater 12 is controlled by a controller 42.

The measuring system 4 is designed here as an ultra-wideband radar device 44 and has a transmitting device 14, a receiving device 24 and a processing device 5. The measuring system 4 operates substantially similar to that in the FIG. 3 The measuring system 4 shown here determines, based on the change in the wave property of the received measuring radiation with respect to the transmitted measuring radiation, a spatial power distribution of electromagnetic radiation. In this case, the power of the measuring radiation absorbed by the treatment space 3 and / or by the material to be treated 200 is determined as a function of the frequency. The measurement system may also include an ultra-wideband radar device 44 or a reflectometer device 54 as previously described.

Depending on which power of the measuring radiation of a certain frequency arrives at the receiving device 24, the common cavity resonances of the treatment chamber 3 and 200 treated material can be determined for this frequency. The ultra-short pulses emitted as measuring radiation are preferably in the range of picoseconds to nanoseconds or even microseconds. The frequency bandwidths associated with Fourier transformation are in particular in the range of a few 10 MHz to 1 Hz. Advantageously, the pulse duration is chosen so that the reflected measuring radiation in the treatment chamber 3 is not superimposed on the way to the receiving device 24 with the incoming pulse. In particular, the pulse length is selected to be so short that multiple reflections from different regions of the treatment space 3 can be discriminated from reflections at the treatment space 200. Preferably, the time window is set as described above.

Due to the frequency-dependent difference between transmitted and received power of the measuring radiation, cavity resonances appear at certain frequencies. In such Cavity resonances particularly high radiation power is absorbed by the treated 200 and treatment room 3. In this case, it is preferably assumed that the treatment area 3, which is usually metallically lined, exhibits a negligible absorption compared to the material 200 to be treated. The cavity resonances are in particular interpreted as describing the field distribution or the spatial distribution of electromagnetic power supply within the treatment space and in particular within the material to be treated 200.

The cavity resonances therefore decisively determine the temperature distribution in the material to be treated 200. The cavity resonances thus described by the measuring system 4 can essentially also be transferred to the radiation power supplied by the heating device 12 into the treatment space 3. Thus, it can be predicted which cavity resonances will occur with the heater active. Such a measuring method thus has the advantage that the spatial distribution of the radiation powers that can be supplied by the heating device 12 can be described in detail in a treatment space 3 of a given material 200 to be treated. As a result, the power supply to the material 200 can be influenced in a targeted manner, for. B. by Stirrer or orientation of the material 200.

In this case, the complex permittivity for each measurement frequency in the frequency band of the ultra-wideband radar device 44 is preferably determined. Thus, for the material to be treated 200, the absorption, reflection and transmission of electromagnetic radiation power of the respective frequency can be determined.

The domestic appliance 1 shown here also has the advantage that the heating device 12 can be controlled in accordance with the previously determined spatial power distribution. For this purpose, by means of the oscillator device 52 radiation power can be generated at the specific frequency or in a specific frequency range. The oscillator device 52 is operatively connected to the control device 42 and controllable by this. As a result, the frequency of the radiation power emitted by the heating device can be set as a function of the power distribution or the determined cavity resonances determined by the measuring system.

Depending on whether a high or low power supply to the material to be treated 200 is desired, a frequency is chosen for which the item to be treated has previously shown a high or low absorption capacity in the measuring cycle. It is also possible for the heating device 12 to emit radiation power at different frequencies over time so that certain field distributions or cavity resonances can be superimposed in succession over time. With knowledge of the spatial absorption capacity of the material to be treated 200 is also possible, certain areas of the material to be treated 200 a supply high radiation power and administer a correspondingly low radiation power to other areas. For example, food can be heated more in an inner area than in an outer area.

The FIG. 7 shows a trained as a cooking appliance 100 home appliance 1 with a measuring system 4. The measuring system 4 substantially corresponds to the measuring system 4, as shown in the FIG. 6 has been described. The heating device 12 has a transmission device 22 here. The transmission device 22 is connected to the heater 12 via a waveguide device 72. The transmission device 22 is provided here to distribute the electromagnetic radiation power generated by the heater 12 in the treatment room 3. For this purpose, the transmission device 22 may be formed, for example, as a stirrer or impeller or the like. In this case, in particular, metal-conducting metal sheets are provided which are moved by a motor and lead to a deflection of the radiation power emitted into the treatment chamber 3. Thus, depending on the position of the stirrer or the rotary vane different vibration modes or cavity resonances in the treatment chamber 3 are achieved.

The cooking device 100 here also has a positioning device 32. The positioning is designed, for example, as a turntable and serves to position or move the material to be treated 200 in the treatment space 3.

The transmission device 22 is here operatively connected to a control device 42, which in turn is operatively connected to the measuring system 4. As a result, the transmission device 22 can be controlled as a function of the information determined by the measuring system. In this case, the transfer device 22 is preferably aligned so that a desired power supply to the material to be treated 200 is achieved. This z. B. user-set programs or other targets. The change in the cavity resonances in the treatment chamber 3 after changing the position of the transmission device 22 can be monitored by the measuring system 4. For example, the measuring system 4 again transmits the cavity resonances when the transmission device 22 has been changed. It is also possible that the positioning device 32 is set as a function of the cavity resonances determined by the measuring system 4.

By means of the transmission device 22 and / or by the positioning device 32 and its control as a function of the determined power distribution, different resonances in the treatment space 3 can be realized in a timely succession. Thus, various spatial distributions for the input of power into the material to be treated 200 can be realized. The residence times when starting a specific cavity resonance are described in particular by a weighted sum. It is determined how long each resonance is to be approached for an optimal result. It can also be set be how to realize the corresponding cavity resonance, ie z. B. by the positioning device 32 or by a corresponding adjustment of the transmission device 22nd

The desired cavity resonance can also be approached by the heater 12 emits radiant power at a certain frequency, as for example for the cooking appliance 100 in the FIG. 6 has been described. In this case, the information contained in the weighted sum may preferably have been determined in advance by a simulation or also by tests. This information and other previously determined parameters of a power distribution are preferably stored as reference parameters in a memory device of the domestic appliance 1. When selecting a corresponding automatic program or another target by the user, the reference parameters are then adapted to the situation.

LIST OF REFERENCE NUMBERS

1

household appliance

2

treatment facility

3

treatment room

4

measuring system

5

processing device

6

operating device

7

memory device

12

heater

13

oven

14

transmitting device

22

transmission equipment

24

receiver

32

positioning

42

control device

44

Ultra-wideband radar device

52

oscillator means

54

Reflektometereinrichtung

62

amplifier means

72

Waveguide device

100

Cooking appliance

103

heating source

104

door

140

transmitting device

200

treated

240

receiver

440

antenna

441

antenna

Claims (17)

Method for operating a domestic appliance (1) with at least one heating device (12) for the dielectric heating of material to be treated (200) by electromagnetic radiation in at least one treatment space (3),
characterized,
that at least one measuring system (4) temporarily generates at least electromagnetic measuring radiation and transmits at least one transmitting device (14) into the treatment chamber (3) and that at least temporarily by at least one receiving means (24) of the measuring system (4) into the treatment space (3) at least one measure of an at least one processing device (5) based on the change in the wave property of the received measurement radiation with respect to the transmitted measurement radiation spatial power distribution of the heating device (12) in the treatment chamber (3) can be supplied radiation is determined. Method according to the preceding claim, characterized in that the spatial power distribution after the introduction of the material to be treated (200) in the treatment chamber (3) is determined. Method according to one of the preceding claims, characterized in that the determined power distribution describes at least one mode for the electromagnetic field distribution in the treatment space (200) and / or at least one resonance of the deliverable radiation in the treatment space (200). Method according to one of the preceding claims, characterized in that the material to be treated (200) is aligned as a function of the determined power distribution by at least one positioning device (32) in the treatment space (3). Method according to one of the preceding claims, characterized in that the heating device (12) has at least one adjustable transmission device (22) for directed introduction of the electromagnetic radiation into the treatment space (3), wherein the transmission device (22) is set as a function of the determined power distribution , Method according to one of the preceding claims, characterized in that the power of the electromagnetic from the heater (12) sent Radiation in dependence of the determined power distribution by at least one control device (42) is set. Method according to one of the preceding claims, characterized in that the measuring radiation comprises at least two frequencies differing by at least 100 MHz between 10 megahertz and 1 terahertz and / or that the measuring radiation has a frequency width of at least 10% of the center frequency of the frequency band used. Method according to one of the preceding claims, characterized in that the spatial power distribution for at least two frequencies and / or as a function of the frequency is determined. Method according to the preceding claim, characterized in that the heating device (12) emits electromagnetic radiation in an at least partially adjustable frequency range, the frequency range of the heating device being adjusted as a function of the determined spatial power distribution for at least one frequency by at least one control device (42). Method according to the preceding claim, characterized in that based on the determined spatial power distribution at least one frequency is determined at which the material to be treated (200) in the treatment room (3) has a certain and / or the highest possible power consumption. Method according to one of the preceding claims, characterized in that the determined power distribution is compared with at least one stored in at least one memory device (7) reference parameter. Domestic appliance (1) with at least one heating device (12) for the dielectric heating of material to be treated (200) by electromagnetic radiation in at least one treatment space (3),
characterized,
in that at least one measuring system (4) is provided with at least one processing device (5) and that the measuring system (4) is suitable and designed to generate electromagnetic measuring radiation, wherein the measuring system (4) at least one transmitting device (14) for at least temporary transmission Electromagnetic measuring radiation into the treatment room (3) and at least one receiving device (24) for at least temporarily receiving the in the treatment room (3) has transmitted measuring radiation and that the measuring system (4) is suitable and designed to detect at least one characteristic variable for a wave property of the received measuring radiation and in that the processing device (5) is suitable and designed based on the change of the wave property of the received measuring radiation With respect to the transmitted measuring radiation, at least one measure of a spatial power distribution of the radiation that can be supplied by the heating device (12) into the treatment space (3) can be determined. Domestic appliance (1) according to the preceding claim, characterized in that at least one positioning device (32) is provided which is adapted and configured to align the material to be treated (200) in dependence on the determined power distribution in the treatment room (3) and / or that Heating device (12) at least one adjustable transmission device (22) for the directed introduction of the electromagnetic radiation in the treatment chamber (3), wherein the transmission device (22) is suitable and designed, depending on the determined power distribution set by at least one control device (42) to become. Domestic appliance (1) according to one of the preceding claims, characterized in that the heating device (12) is suitable and designed to emit electromagnetic radiation power in a frequency range which can be set as a function of the determined power distribution. Domestic appliance (1) according to one of the preceding claims, characterized in that the transmitting device (14) and / or the receiving device (24) are at least partially designed and suitable for measuring radiation at least two different frequencies between 10 megahertz and 100 gigahertz in a frequency bandwidth of to process at least 10% of the center frequency of the frequency band used. Domestic appliance (1) according to one of the preceding claims, characterized in that the transmitting device (14) is at least partially designed and suitable to emit measuring radiation as at least one pulse with a pulse duration shorter than a nanosecond at least temporarily and in particular repeatedly. Domestic appliance (1) according to one of the preceding claims, characterized in that the measuring system (4) comprises at least one ultra-wideband radar device (44) and / or is designed as such.

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