JP2000243537A - Heating device, heat fixing device, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure heating without generating a flicker even when preheating is performed by providing two heating resistors having different resistance on a board, and connecting them to a different power source input system, and always electrifying one of the heating resistors. SOLUTION: A board 25 is provided with separate two heating resistors 32, 33, and each heating resistor is connected to a different power source input system. One of the heating resistors is formed of a high-resistance heater 32 for preheating, and the other is formed of a heating resistor 33 for heating. A glass layer having excellent heat conductivity is provided on the board 25 provided with the heating resistors 32, 33 so as to hold the breakdown voltage for safety. A heating device using this heater is applied for heating and fixing device. The heating resistor 32 for preheating desirably has a resistance of 40 Ω. The high-resistance heater 32 for preheating of two-piece heating resistors is provided upstream in the recording material carrying direction, and the low- resistance heater 33 for heating is provided downstream thereof at a position capable of being surely housed in a fixing nip.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film heating type heating apparatus for applying heat energy to a material to be heated via a heat-resistant film.

[0002]

2. Description of the Related Art An image heating apparatus in an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, a recording apparatus, or the like, that is, an image forming process means such as electrophotography, electrostatic recording, and magnetic recording. Recording materials (electrofax sheets, electrostatic recording sheets,
Transfer material sheet, print sheet, etc.) directly or indirectly (transfer) formed, and a toner image as an unfixed image corresponding to the target image information is permanently fixed to the recording material surface carrying the image. It is used as a heating device to heat and fix it as an image.

The heating device is not limited to the image heating and fixing device, and heats an image carrier as a material to be heated widely, for example, by heating a recording material carrying an image to improve the surface properties. It can be used as a means / device.

Conventionally, as a method of fixing an unfixed image on a recording material by applying the above-described heating device, a contact heating type fixing device having good thermal efficiency and safety is widely known.
Particularly, in recent years, from the viewpoint of promoting energy saving, a fixing method of a film heating device that heats through a fixing film having a small heat capacity has attracted attention as a method having a high heat transfer efficiency and a rapid rise in temperature. 31318
No. 2, JP-A-2-1577878, JP-A-4-15778
These are proposed in JP-A-44075 to JP-A-4-44083, JP-A-4-204980 to JP-A-4-204498, and the like.

[0005] The fixing device of the film heating system includes a method of conveying the fixing film between the pressure roller while applying tension using a dedicated conveying roller and a driven roller, and a method of adding a cylindrical fixing film. There is a method of driving by the conveying force of the pressure roller. The former has an advantage that the conveyability of the fixing film can be enhanced, and the latter has an advantage that the configuration can be simplified and a low-cost fixing device can be realized.

FIG. 14 is a view of the heater substrate viewed from above, and FIG. 15 is an enlarged cross-sectional view thereof. Two heating elements 22 are provided on the surface of a ceramic substrate 25 as a heating element.
Are provided in parallel, one end of which is connected to a main body computer (not shown) from a heating element contact 23, the other end of which is connected to each other via a connection conductor 28, and the two heating elements 22 are substantially It is configured as one heating resistor. Also,
The heating resistor 22 is provided on a ceramic substrate 25 on which the heating resistor 22 is printed in order to maintain a withstand voltage for safety.
A plurality of glass layers 26 having good heat conductivity are provided.

The printer controls the amount of heat generated by energizing the heat generating resistor 22 by looking at the amount of heat generated. The thermistor 24 is mainly used as a method of checking the heat generation amount. In most cases, the on-demand heat fixing device is provided with a thermistor 24 and a thermistor electrode pattern 27 as temperature detecting means directly on the back surface of the substrate. Then, information obtained by the thermistor 24 is transmitted to a computer on the main body side through a thermistor electrode pattern contact 27.

[0008]

However, the heating and fixing device to which the conventional heating device is applied has the following problems.

[0009] With the recent development of the computer industry, laser beam printers, which are also peripheral equipment, have come to be used in various countries around the world. Opportunities have increased for printing on different types of paper and paper with different surface properties. In addition to the diversification of paper types, the speed of the image forming apparatus itself has been increased, and the amount of instantaneous heat applied from the heater to the recording material has been reduced from the viewpoint of shortening the printing time of the first sheet and securing the fixing property of the first sheet. By increasing it little by little, satisfactory fixability is obtained.

[0010] However, in the various paper types used in various countries as described above or in demand for high speed, simply increasing the instantaneous calorific value does not ensure the fixing property immediately after the apparatus is started. It is difficult, and an image having a poor fixing may appear immediately after the apparatus is started.

Further, in order to increase the speed of on-demand fixing, the paper feeding speed is increased, and in order to obtain satisfactory fixing performance, the resistance of the heating element itself is reduced to increase the supplied electric power. The amount of heat generated must be increased. Alternatively, regardless of whether or not the sheet is not passed, preheating is performed to energize the heating resistor and preheat it to a certain temperature to shorten the time required to reach the target temperature, and the sheet must be passed after the sheet is sufficiently warmed. FIG. 15 shows the results of evaluation of the fixing property when preheating is performed.

The input voltage is 100 V and the transfer speed is 2
The fixing temperature was set to 0 ppm and the control temperature at the time of fixing was set to 200 ° C. As is clear from FIG. 15, it can be seen that the preheating improves the fixing property in accordance with the set temperature.

However, when the temperature of the heating resistor set at a high temperature range exceeding 150 ° C. at the time of fixing operation is controlled at a low temperature of 100 ° C. or less, the ON / OFF of energization is performed.
The timing is very early, and a flicker phenomenon occurs in which electric lamps such as incandescent lamps and fluorescent lamps connected to the same power supply system flicker according to the timing. Therefore, it is difficult to achieve both fixing and preheating using the same heating resistor. Also, 6
If it is 0 degrees or more, flicker does not occur and the fixability is good.
There is a problem in that heat-resistant grease oozes out from the edge of the fixing film.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a heating apparatus capable of securing a heating property without causing a flicker phenomenon even when preheating is performed. .

It is another object of the present invention to provide a heating and fixing device which can reliably perform fixing without being affected by the size of a recording material by applying the heating device.

Another object of the present invention is to provide an image forming apparatus which performs a high quality image forming operation by a smooth fixing operation by applying the heat fixing device.

[0017]

According to the present invention, there is provided a heating apparatus, a heat fixing apparatus, and an image forming apparatus having the following constitution.

(1) A heating apparatus in which a heater is adhered to one surface of a heat-resistant film and a material to be heated is adhered to the other surface, and heat energy of the heater is applied to the material to be heated via the heat-resistant film. The above-mentioned heater is characterized in that two heating resistors having different resistance values are provided on a substrate, each of which is connected to a different power input system, and one of the heating resistors is always energized to perform preheating while the apparatus is on standby. And a heating device.

(2) The heating device according to (1), wherein the heating resistor having a large resistance value among the two heating resistors is a heating resistor for preheating.

(3) Of the two heating resistors, the heating resistor having a higher resistance value is located upstream of the other heating resistor in the paper passing direction. (1) A heating device as described.

(4) The heating device according to (1), wherein each of the two heat generating resistors has a different shape, and has a high heat generating portion and a low heat generating portion in the longitudinal direction.

(5) Of the two heating resistors, one has a length of the heating element that mainly heats the small-sized heated material, and the other has heating portions at both ends to complement the heating element. The heating device according to (1), which is installed.

(6) The heating device according to any one of (1) to (5) and a material to be heated having an unfixed image are pressed by the heater through the heat-resistant film. And a pressing member for fixing an unfixed image on the material to be heated as a permanent image to the material to be heated by the heat energy of the heater applied through the heat-resistant film to be moved together with the heat-resistant film. A heat fixing device characterized by the above-mentioned. (7) An image forming apparatus comprising: an image forming means for forming and supporting an unfixed image on a material to be heated; and a heat fixing means for heating and fixing the unfixed image formed and supported on the recording material to the recording material. The image forming apparatus according to (1), wherein the heating device according to (6) is used as the heat fixing unit.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a plan view showing a heater of a heating device according to Embodiment 1 of the present invention,
5 are provided with two independent heating resistors 32 and 33, which are respectively connected to different power supply input systems, one of which is a high-resistance heating member 32 for preheating, and the other is a heating resistor 33 for heating. Configuration. In addition, in order to maintain safety withstand voltage, a glass layer having good heat conductivity is provided on the substrate 25 on which the heating resistors 32 and 33 are provided. FIG. 2 is a diagram showing a fixing result when a heating device using this heater is applied to a heat fixing device. The heating resistor 32 for preheating has a resistance value of 40Ω. As shown here, there is almost no difference in the fixability, but the flicker phenomenon is as shown in FIG.

The flicker phenomenon has a standard of Pst (short term flicker value) = 1.0 or less. However, this standard is a European standard of 230 V and 16 A or less. Therefore, in the first embodiment, an incandescent lamp was connected to the same power supply as that of the laser beam printer in which the fixing device to be evaluated was inserted, and the visual confirmation was performed with input of 100 V and 50 Hz, which are common voltages in Japan. Looking at this result, although it is a visual check, the flicker phenomenon is reduced by dividing the single heating element into a single heating element rather than performing the dual role of fixing and preheating, and by using a high resistance heating element for the heating resistor for preheating. It became possible to prevent.

Further, a high-resistance heating element 32 for preheating the divided heating resistors is installed on the upstream side in the recording material conveyance direction, and a low-resistance heating element for heating is conversely placed in the fixing nip on the downstream side. Installed in a position that always fits. This is because, as shown in FIG. 4, when the heating heating element 34 is near the recording material entry point of the fixing nip, the water vapor 36 absorbed by the recording material 35 searches for an escape route outside the fixing nip by the heat, and the paper passing direction. Jumps out to the other side. Then, if the unfixed toner 37 exists at the place where the toner has popped out, it will be blown off and will appear in the image as a tail.

Conversely, if the heating resistor 33 for heating is located in the back of the fixing nip where the recording material is pressed against the heater, the heating is performed after the recording material is completely sandwiched between the fixing nip, so that the water vapor escapes. Even if the recording material escapes in the recording material intrusion direction as described above, the unfixed toner strongly nipped by the fixing nip is not blown away. Therefore, the effect of the tailing was confirmed for the heating resistor 33 provided near the entry of the recording material into the fixing nip and the heating resistor 33 provided at the back of the fixing nip. FIG. 5 shows the result. It is better to install the heating resistor 33 in the downstream area than the heating resistor 32 for preheating.
Advantageous for tailing.

As described above, according to the first embodiment, since the heating resistors 32 and 33 are connected to separate power supply systems, it is possible to perform preheating without causing a flicker phenomenon. The preheating makes it possible to obtain a satisfactory fixing property with respect to an increase in the paper passing speed, and it is possible to prevent the unfixed toner from adhering to the pressure roller and the fixing film and fouling. In addition, of the two heating resistors, a heating resistor having a higher resistance for preheating is provided in an upstream region, and a heating resistor having a lower resistance is provided in a downstream region, thereby causing tailing. Can be difficult
Stable high-speed on-demand heat fixing device
High quality fixing can be performed.

Embodiment 2 FIG. In the first embodiment, the effect of fixing property, flicker and tailing was recognized by providing two heating resistors having different power supply connections and performing preheating. However, if the preheating time is too long, or if the preheating temperature is set higher than 50 degrees, the heat resistant grease may seep out from both ends of the fixing film.

Therefore, in the second embodiment, as shown in FIG. 6, the heating patterns of the two heating resistors of the heating ceramic heater are formed in different shapes, and the heating resistor 38 which mainly preheats the central portion is used. And a heating resistor 39 covering the entire width of the recording material to prevent the heat-resistant grease from seeping out from the end of the fixing film.

Here, in order to confirm the effect of the preheating, a thermocouple is installed on a heater substrate provided with a heating resistor, and the temperature of the heating resistor 38 for preheating is controlled to 60 ° to the end when the temperature is controlled to 60 degrees. The preheat temperature was measured. FIG. 7 shows the result. The portion where the heating resistor 38 is located is heated to approximately 60 degrees, and the temperature decreases toward the end. However, the temperature at the extreme end is 30 degrees or more (room temperature 20 degrees).
Degree), central centralized preheating is possible. In addition, although this evaluation was continuously performed for about one hour, it was not confirmed that the heat-resistant grease exuded.

Then, when the fixing property was evaluated with this configuration, as shown in FIG. 8, the fixing property was somewhat inferior to that in which the heat-generating low antibody for preheating was installed in the entire longitudinal region. In particular, such a tendency appears at an end portion which becomes lower with respect to the control temperature. However, on the other hand, even if the preheating temperature is set somewhat higher, the fixing property can be covered because the heat-resistant grease hardly exudes from the end. In addition, since the preheating temperature of the central heating element itself can be set higher, it is possible to contribute to the fixing property without worrying about the flicker phenomenon.

Further, it was examined whether the heating resistor 38 in the central portion can improve the temperature rise in the non-sheet passing portion when a small-sized recording material is passed. First, the heating resistor 38 has a length that can cover the width of an envelope that is a small-sized recording material. Therefore, when the effect is confirmed by actually passing the envelope through paper, as shown in FIG. 9, compared with the heating curve 40 in the case of using a normal heating element, the heating was performed by the heating heating resistor 38 in the center. It can be seen that the temperature rise curve 41 in the case is clearly improved.

The temperature was controlled at 200 ° C.
However, when two heating resistors 38 and 39 having the same width are arranged side by side on the ceramic substrate as shown in FIG. 6, the width of the ceramic substrate itself becomes large, and the entire fixing device becomes large.

Therefore, the heating resistor in the center is left as it is, and the other heating resistor covering the entire longitudinal area is formed in a shape as shown in FIG. 10 to complement the heating resistor in the center. In other words, by providing a complementary pattern of the heating resistor 43 at both ends with respect to the pattern of the heating resistor 42 at the center, the entire recording material width can be covered. Here, when the fixing property and the temperature rise in the non-sheet passing portion were confirmed, the fixing property showed almost the same value as in the central concentrated preheat type in FIG. 8, and the temperature rising in the non-sheet passing portion was also the same as in FIG. It was the same.

As described above, according to the second embodiment, the heating resistors connected in different power input systems cover the heating resistor 42 of the central heating pattern and the entire recording material width. Heating resistor 43 with complementary heating pattern
Is used, the fixing property can be satisfied by preheating the heating resistor 42 at a higher set temperature, and a heating and fixing apparatus without a flicker phenomenon can be realized. In addition, when a small-sized recording material such as an envelope is passed through Of the non-sheet passing portion can be eliminated. By using the heating resistor 43 covering the entire recording material width at both ends of the heating resistor 42 at the center,
It is possible to provide a heat fixing device that can reduce the width of the ceramic substrate itself having the heat generating resistor, has almost the same size as the conventional one, and can realize higher speed.

Embodiment 3 FIG. 11 shows the configuration of the heat fixing device 7 to which the heating device of the present invention is applied.
In the figure, reference numeral 10 denotes a pressure roller comprising an elastic layer 20 formed by foaming a heat-resistant rubber such as silicon rubber or fluorine rubber or silicon rubber on the outside of a cored bar 21. PFA, PTFE is provided on the elastic layer 20. , FEP or the like.

Reference numeral 14 denotes a fixing film having a small heat capacity, which is a heat-resistant and thermoplastic polyimide, polyamide, PEEK, PES, PPS, PFA, PTFE,
It is a fixing film such as FEP. Furthermore, in order to prevent offset and ensure the separation property of the recording material, PFA,
A heat-resistant resin such as PTFE and FEP having good release properties is mixed or coated alone. Thermistor 1
6, a heater composed of a heater substrate 17 and a heating element 18 is provided inside the fixing film 14 and heats a nip for melting and fixing a toner image on a recording material.

Reference numeral 15 denotes a heat insulating support member for holding a heater and preventing heat radiation in a direction opposite to the nip. The heat insulating support member 15 is formed of a liquid crystal polymer, a phenol resin, PPS, PEEK, or the like. It has a shape and size that can be turned around with ease. Further, since the fixing film 14 rotates while sliding on the internal heater and the heat insulating support member 15, it is necessary to reduce the frictional resistance between the heater and the heat insulating support member 15 and the fixing film 14. For this reason, the heater and the heat insulating support member 15
A small amount of lubricant such as heat-resistant grease is interposed on the surface of. Thus, the fixing film 14 can rotate smoothly.

The fixing member 9 is constituted by the fixing film 14, the heat insulating support member 15, and the heater (constituted by 16, 17, and 18).

FIG. 12 shows the heat insulating support member 1 of the heat fixing device 7.
FIG. 5 is a side view of 5. The heat-insulating support member 15 includes a heating body support portion 29 and a guide portion 31, and in particular, the guide portion 3.
1 is for maintaining the shape of the fixing film, and the guide portion 31 between the ribs 30 is not supported by the heat applied to the fixing film 14 from the heating element due to the contact with the ribs 30. Reduce uniformity.

Next, the operation will be described.

The recording material having an unfixed toner image passes between the pressure roller 10 of the heat fixing device 7 and the fixing nip formed by the fixing film 14, and the heat of the heat generating resistor 22 generated by energization and the pressure roller With the pressing force from 10, the unfixed toner image is melted and fixed on the recording material. The conveying force at this time is limited to only the pressure roller in the case of the heat fixing device 7 of the pressure roller driving type fixing film type, and the fixing film itself takes a driven shape and moves together with the recording material.

Embodiment 4 FIG. 13 is a configuration diagram showing an image forming apparatus to which the heat fixing device of the third embodiment is applied. In FIG. 15, reference numeral 1 denotes a photosensitive drum,
A photosensitive material such as amorphous Se or amorphous Si is formed on a cylindrical substrate such as aluminum or nickel. The photosensitive drum 1 is driven to rotate in the direction of the arrow, and its surface is first uniformly charged by a charging roller 2 as a charging device. Next, ON / OFF according to the image information
Scanning exposure is performed by the laser beam 3 controlled to be OFF, and an electrostatic latent image is formed. This electrostatic latent image is developed and visualized by the developing device 4. As a development method, a jumping development method, a two-component development method, an FEED development method, or the like is used, and a combination of image exposure and reversal development is often used. The visualized toner image is transferred from the photosensitive drum 1 onto the recording material 8 conveyed at a predetermined timing by a transfer roller 5 as a transfer device. At this time, the recording material 8 is nipped and conveyed to the photosensitive drum 1 and the transfer roller 5 with a constant pressing force. The recording material 8 to which the toner image has been transferred is conveyed to the heat fixing device 7 and fixed as a permanent image. On the other hand, the transfer residual toner remaining on the photosensitive drum 1 is removed by the cleaning device 6.
Removed from the surface.

[0046]

As described above, according to the present invention, a heater provided with two heating resistors having different resistance values is used, each of which is connected to a different power supply input system, and the apparatus is in standby mode.
Since one of the heat generating resistors is configured to be pre-heated by being constantly energized, it is possible to preheat to a temperature slightly higher than the room temperature regardless of the installation environment without worrying about the flicker phenomenon.

Further, even if the speed is increased by using one of the two heat generating resistors as a heater dedicated to small size paper such as an envelope, the type of recording material will be further increased in the future. Even if the printing is performed, it is possible to prevent the temperature rise in the non-paper passing area as much as possible, set the throughput without worrying about the temperature rise in the non-paper passing area, and use a recording material with various widths. There are effects such as enabling excellent high-speed heating of the parhand link.

Also, by applying this heating device, excellent fixing properties can be obtained even at the lowest temperature.
There is an effect that it is possible to obtain a heat fixing device capable of preventing the fixing film and the pressure roller from being stained by toner adhesion.

Further, by applying this heat fixing device, there is an effect that an image forming device capable of forming a high quality image by a smooth fixing operation can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a heater including a divided high-resistance heating element and a low-resistance heating element connected to another power supply system according to Embodiment 1 of the present invention.

FIG. 2 is a graph showing a relationship between preheating and fixability of a heater using a single heating resistor and a heater using a divided heating resistor.

FIG. 3 is a diagram illustrating a flicker phenomenon level with respect to a preheating temperature of a heater using a single heating resistor and a divided heating resistor.

FIG. 4 is a schematic diagram showing a tailing generation mechanism.

FIG. 5 is an explanatory diagram showing a difference in trailing occurrence at an installation position of a divided heating resistor connected to another power supply system.

FIG. 6 is a schematic diagram of a heater provided with a central concentrated preheat heating resistor according to Embodiment 2 of the present invention.

FIG. 7 is a graph showing the preheating temperature over the entire length of the heater including the central concentrated preheating heating resistor during preheating.

FIG. 8 is a graph showing a relationship between a set preheating temperature and a fixing property of a heater having a central concentrated preheating resistor.

FIG. 9 is a graph showing a non-sheet-passing portion temperature rise when a small-size recording material is passed by a heater including a central-portion preheating heating resistor according to Embodiment 2 of the present invention.

FIG. 10 is a schematic diagram showing a relationship between a central concentrated preheating heating resistor according to a second embodiment of the present invention and a complementary heating resistor arranged to complement the heating resistor.

FIG. 11 is a cross-sectional configuration diagram illustrating a configuration of a heat fixing device according to Embodiment 3 of the present invention.

FIG. 12 is a side view of a heat insulating support member according to Embodiment 3 of the present invention.

FIG. 13 is a schematic configuration diagram illustrating an image forming apparatus according to Embodiment 4 of the present invention.

FIG. 14 is a schematic view showing a heater of the heat fixing device.

FIG. 15 is an enlarged cross-sectional view of a heater.

FIG. 16 is a diagram showing evaluation results of fixability when preheating is performed using the heater of FIG.

[Explanation of symbols]

Reference Signs List 10 pressure roller (pressure member), 11 recording material, 14 fixing film, 15 heat insulating support member, 16 thermistor
(Fixing member), 17 heater substrate (fixing member), 18 heating resistor (fixing member), 22, 23, 38, 39 heating resistor.

Claims (7)

[Claims] 1. A heating device for adhering a heater to one surface of a heat-resistant film and a material to be heated to the other surface, and applying heat energy of the heater to the material to be heated via the heat-resistant film. The above-mentioned heater is characterized in that two heating resistors having different resistance values are provided on a substrate, each is connected to a different power input system, and one of the heating resistors is always energized during standby of the device to perform preheating. Heating equipment. 2. The heating device according to claim 1, wherein a heating resistor having a large resistance value among the two heating resistors is used as a heating resistor for preheating. 3. The heating resistor having a larger resistance value among the two heating resistors is located upstream of the other heating resistor in the paper passing direction. Heating equipment. 4. The heating apparatus according to claim 1, wherein each of the two heat generating resistors has a different shape, and has a high heat generating portion and a low heat generating portion in a longitudinal direction. 5. One of the two heating resistors has a length such that the heating member mainly heats the small-sized heated material,
2. The heating device according to claim 1, wherein heat generating portions are provided at both ends to complement the other. 6. The heating device according to claim 1, wherein a material to be heated having an unfixed image is pressed by the heater through the heat-resistant film. A pressurizing member for moving the unfixed image on the material to be heated as a permanent image on the material to be heated by the heat energy of the heater applied through the heat-resistant film to be moved together with the film. Characteristic heat fixing device. 7. An image forming apparatus comprising: an image forming means for forming and supporting an unfixed image on a material to be heated; and a heat fixing means for heating and fixing the unfixed image formed and supported on the recording material to the recording material. 7. An image forming apparatus, wherein said heat fixing means is the heat fixing device according to claim 6.