JPH1195586A - Heating element, heating/fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-reliable heating element which is capable of preventing the rising of temp. as in the conventional manner, when abnormality occurs and has higher strength normally by providing a dispersion means for dispersing heat in a fixed region where a temperature detecting means exists. SOLUTION: The heating element is provided on the front surface of a ceramic substrate as a heating body and for measuring the temp., a thermistor 16 as a temperature detecting means and a thermistor electrode pattern 32 are provided on the rear surface of the ceramic substrate. The heating body is stuck to a heating body supporting part, in such a manner that the thermistor 16 and a region 34 on the side of the thermistor electrode pattern 32 are fully coated with a high-temperature conduction silicone adhesive as the dispersion means and the thermistor 16 on the opposite side and a region 35 not including the thermistor electrode pattern 32 are fully coated with a silicone adhesive having normal heat conductivity, in the longitudinal direction of the substrate of the heating body. Thus, the short, circuit of the heating element and the thermistor electrode pattern 32, due to the damage of the thermistor 16 and the thermistor electrode pattern 32 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using, for example, an electrophotographic system or an electrostatic recording system.
Regarding a heat fixing device for fixing toner and the like on a recording material,
In particular, it relates to a heating element provided in the heat fixing device.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus provided with a heat fixing device having a heating element of this type, for example, there are a printer, a copying machine, a facsimile and the like using an electrophotographic system. As a method for fixing an unfixed image on a material, a contact heating type heat fixing device having good thermal efficiency and safety is widely known.

In recent years, in particular, from the viewpoint of promoting energy saving, a film heating type fixing method in which heating is performed via a fixing film having a small heat capacity has attracted attention as a method having a high heat transfer efficiency and a quick start-up of the apparatus. Showa 6
JP-A-3-313182, JP-A-2-157784,
-44075-44083, 4-204980-204
No. 984, for example.

As a configuration of a heat fixing device of a film heating type, there are a method of conveying a fixing film between a pressure roller and a tension roller by using a dedicated conveying roller and a driven roller for conveying the fixing film, There is a method of driving the cylindrical fixing film with the conveying force of the pressure roller. The former has the advantage of improving the conveying property of the fixing film, and the latter realizes a low-cost on-demand heat fixing device with a simplified configuration. There are advantages that can be done.

As a specific example, FIG. 16 shows a cross-sectional configuration of a film fixing device driven by a pressure roller.

In FIG. 16, an image formed by an unfixed toner 102 formed on a recording material 101 is pressed between pressure rollers 100 made of heat-resistant rubber and is rotated by the rotation of the pressure roller 100 due to friction. It is conveyed to the nip portion between the cylindrical fixing film 104 that is rotated and conveyed along the heat insulating support member 105 also serving as a member, and is heated via the fixing film 104 (thermistor 106 serving as a temperature detecting element, ceramic substrate 107, heating element) 108) and is fixed as a permanent image 103 by heating and pressurizing by the heating element 108 on the upper side.

The heat insulating support member 105 in the heat fixing device
Has a shape as shown in FIG.

A rib 109 is provided in the upstream area and the downstream area for the purpose of smooth rotation of the fixing film 104 in the film heating system and maintaining the shape of the fixing film.

The heating element supporting portion 110 of the heat insulating supporting member 105 has a shape as shown in FIG. 18, and includes a heating element supporting surface 111, an adhesion point 112, and a counterbore 113.

A heating-substrate ceramic substrate as shown in FIG.
And is bonded to the bonding point 112 with a thermosetting adhesive having good heat conductivity.

The heating element shown in FIG. 19A is provided with a heating element 108 on the heating surface, and a glass layer is formed on the surface thereof for the purpose of withstand voltage and slidability of the fixing film.

The heating element contacts 114 and the thermistor electrode pattern contacts 115 are connected to the printer body.

A thermistor body 106 for measuring the temperature of the ceramic substrate is provided on the rear surface of the substrate in the vicinity of the center of the substrate from the thermistor electrode pattern contact 115 to the thermistor electrode pattern 116 on the back surface of the substrate in FIG.

As a safety measure, a weak point such as a through hole 117 is formed so as to penetrate the ceramic substrate in order to escape from a crisis situation such as a fire when an abnormal temperature rise such as thermistor erroneous detection or runaway occurs. Have been.

When the temperature of the substrate reaches an excessive temperature region due to the presence of the through hole 117, the stress generated at the boundary between the portion having the through hole 117 and the portion not having the through hole 117 due to the thermal expansion of the ceramic substrate increases. The breakage starts from the through hole 117 which is a weak point of the above, the heating element 108 formed on the substrate is also disconnected, and the abnormal temperature rise is stopped safely.

However, disconnection of the heating element 108 due to the through hole 117 may cause the thermistor 1 to break in the longitudinal direction of the substrate.
06 and the thermistor electrode pattern 116 side,
Since there is a risk that the heating element 108 connected to the AC circuit and the thermistor electrode pattern 116 connected to the DC circuit may be short-circuited at the end of the broken substrate, the through hole 117 is formed in the longitudinal direction of the thermistor 106 and the thermistor electrode pattern 116 side. It is preferable to provide the heating element contact 114 as far as possible from the heating element contact 114 side.

However, even if it is extremely close to the heating element contact 114, the voltage at the disconnection portion is too high and the generation of sparks due to the contact between the heating elements at the time of disconnection becomes strong, so that a certain interval is required.

[0018]

However, in recent years, with the development of the computer industry, printers as peripheral devices have been exported to countries around the world. Therefore, the number of paper types used in each country is larger than expected, and it has become clear that there are papers with a thickness and surface texture that we cannot imagine.

In particular, when extremely thick paper passes through the heat fixing device, a gap is formed between the pressing roller 100 and the fixing film 104 at both ends of the paper, and a portion where the strength of the ceramic substrate is weak (for example, Through holes)
From there, the heater was sometimes damaged.

At the same time as the variety of paper types is diversified, the speed of the image forming apparatus itself is increased, and from the viewpoint of shortening the printing time of the first sheet and securing the fixing property of the first sheet, the moment when the sheet is put into the heating element. Considering the amount of power and the maximum temperature at startup, etc., if a specially mechanically weakened part is made on the ceramic substrate itself of this heating element,
There have been cases in which damage has occurred during normal use, even when not normal.

The present invention has been made in order to solve the above-mentioned problems of the prior art. It is an object of the present invention to prevent a rise in temperature in the same manner as in the prior art in the event of an abnormality, and to increase reliability in normal times. An object of the present invention is to provide an excellent heating element, a heat fixing device, and an image forming apparatus.

[0022]

According to the present invention, in order to achieve the above object, a heating element which generates heat by energization is provided on a surface of a substrate, and a temperature detecting means for detecting a temperature of the substrate is provided on a back surface of the substrate. In the provided heating element, a dispersing means for dispersing heat in a predetermined area where the temperature detecting means exists is provided.

In a heating element having a heating element which generates heat by energization on the surface of the substrate and a temperature detecting means for detecting the temperature of the substrate on the back surface of the substrate, the substrate is reinforced in a predetermined area where the temperature detecting means exists. Preferably, reinforcing means is provided.

In a heating element having a heating element which generates heat by energization on the surface of the substrate and a temperature detecting means for detecting the temperature of the substrate on the back surface of the substrate, heat is distributed to a predetermined area where the temperature detecting means exists. It is preferable to provide a dispersing means and a reinforcing means for reinforcing the substrate.

It is preferable that the dispersing means adheres the predetermined area of the mounting surface of the heating element supporting portion for supporting the heating element to the heating element with an adhesive having a higher thermal conductivity than the other area.

[0026] It is preferable that the dispersing means is arranged so that the predetermined area is dense and the other area is sparse in the interval between the bonding points on the mounting surface.

[0027] The dispersing means is provided by abutting the heating element and the heating element support portion, and the other area is provided with a notch in which the heating element and the heating element support section do not abut. preferable.

Preferably, the reinforcing means is a coating covering the predetermined area so as to increase strength.

The coating is preferably applied with a high heat conductive member.

Preferably, the high thermal conductive member is made of glass.

Preferably, the high thermal conductive member is made of a conductive resin paint.

Further, in order to achieve the above, in the heat fixing apparatus of the present invention, there is provided a heating member, a fixing film heated by the heating member, and a pressurizing device for pressing the fixing film against the heating member. And fixing an unfixed image on a recording material conveyed between the fixing film and the pressing member.

Further, in order to achieve the above, an image forming apparatus of the present invention is characterized in that it comprises an image forming means for forming an unfixed image on a recording material, and the above-mentioned heat fixing device. I do.

[0034]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the dimensions of the components described in this embodiment,
The material, shape, relative arrangement, and the like are not intended to limit the scope of the present invention only to them unless otherwise specified.

(First Embodiment) In an image forming apparatus according to a first embodiment of the present invention, for example, as shown in FIG. 1, a toner image formed by image forming means is transferred to a recording material, and a heat fixing device is used. 7 and is fixed.

In FIG. 1, reference numeral 1 denotes a photosensitive drum as an image forming means, and a photosensitive material such as OPC, amorphous Se, amorphous Si or the like 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 developing method, a jumping developing method, a two-component developing method, or the like is used, and a combination of image exposure and reversal developing is often used.

The visualized toner image is transferred from the photosensitive drum 1 onto a 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 between 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 from the surface of the photosensitive drum 1 by the cleaning device 6.

FIG. 2 shows the configuration of the heat fixing device 7 according to the first embodiment.

Outside the cored bar 21 is a pressure roller 10 as a pressure member composed of an elastic layer 20 formed by foaming heat resistant rubber such as silicon rubber or fluorine rubber or silicon rubber. A releasable layer 19 of PFA, PTFE, FEP or the like may be formed thereon.

The heating and fixing means 9 comprises the following members. 14 is a fixing film having a small heat capacity,
Heat resistant, thermoplastic polyimide, polyamide, PEEK, PES, PPS, PFA, PTFE, F
It is a fixing film such as EP. Furthermore, in order to prevent offset and ensure the separation property of the recording material, PFA, PT
A heat-resistant resin having good release properties such as FE or FEP is mixed or coated alone.

Thermistor 16, ceramic substrate 1
7. A heating element provided inside the fixing film 14 composed of the heating element 18 heats a nip portion where the toner image on the recording material is melted and fixed.

Reference numeral 15 denotes a heat insulating support member for holding the heating element and preventing heat radiation in a direction opposite to the nip, and is formed of a liquid crystal polymer, a phenol resin, PPS, PEEK, or the like. It has a shape and size that allow it to be turned around in a certain direction.

Further, since the fixing film 14 rotates while rubbing against the internal heating element and the heat insulating support member 15, it is necessary to reduce the frictional resistance between the heating element and the heat insulating support member 15 and the fixing film 14.

For this reason, a small amount of a lubricant such as heat-resistant grease is interposed on the surfaces of the heating element and the heat insulating support member 15. Thus, the fixing film 14 can rotate smoothly.

As described above, the toner sent from the image forming means to the recording material in an unfixed state passes through the nip between the pressure roller 10 of the heating and fixing device 7 and the fixing film 14, thereby causing heat. Is melted and fixed by the compression force. In the case of a pressure roller driving type fixing film fixing device, the conveying force at this time is limited to only the pressure roller 10,
The fixing film 14 itself takes a following shape and moves together with the recording material.

At this time, the heat-resistant grease and the heat-insulating support member 15 play important roles. The heat-resistant grease is used for lubricity between the fixing film 14 and the heat-insulating support member 15, and the heat-insulating support member 15 has a function of preventing heat from the fixing film 14 itself and a function of protecting the shape of the fixing film 14 itself.

FIG. 3 shows the heat insulating support member 15 of the heat fixing device 7.
It is the figure which looked at from the side. The heat insulating support member 15 is composed of a heating element support portion 24 and guide portions 22 and 23. In particular, the ribs 22 in the guide portions 22 and 23 are for maintaining the shape of the fixing film. There is a rib-to-rib guide 23, which is located between the heating element and the fixing film 14.
Is prevented from becoming uneven due to the heat applied to the ribs 22 coming into contact with the ribs 22.

Further, as shown in FIG. 4, the heating element is in contact with a hatched area 25 in the heating element support portion 24. Also,
Adhesion points 26 are provided for fixing the heating element and the heat insulating support member 15.

It should be noted that the bonding points 26 are not limited to the arrangement shown in FIG.
Various patterns are given.

In this embodiment, the bonding point 26 is shown in FIG.
It is like.

A heating element 18 is provided on the surface of a ceramic substrate 17 as a heating element in FIG.
9 and is connected to the main body, and generates heat when the heating element 18 is energized. The printer controls the calorific value based on the calorific value.

The thermistor 1 is used to check the amount of heat generated.
6 is mainly used. In most cases, the on-demand fixing method uses a chip thermistor of a type that adheres directly to the back surface of the substrate.

In this embodiment, the thermistor 16 and the thermistor electrode pattern 32 as temperature detecting means are provided on the back surface of the ceramic substrate 17 for measuring the temperature. The information obtained by the thermistor 16 is sent to the computer on the main body side through the thermistor electrode pattern contact 30.

There is a possibility that the transmission system or the electric circuit or the like will fail to some extent.

Therefore, as a safety measure, in the present embodiment, a predetermined area on the side of the thermistor 16 as the temperature detecting means and the thermistor electrode pattern 32 in the longitudinal direction of the heater substrate is provided on the heater support 24 shown in FIG. Area 3 as
No. 4 as a dispersing means, high thermal conductive silicone adhesive (manufactured by Toray Dow Corning Silicone Co., Ltd .: SE44)
50, a thermal conductivity of 1.88 w / (m × k)), and an area 35 not including the thermistor 16 and the thermistor electrode pattern 32 on the opposite side is a silicone adhesive having ordinary thermal conductivity (Toray) -Dow Corning Silicone Co., Ltd .: SE1750, thermal conductivity 0.63w /
(M × k)), the thermal discrimination is made clear by bonding the heating element, and the heating element 18 and the thermistor electrode pattern 32 are damaged by the thermistor 16 and the thermistor electrode pattern 32 side. Prevent short circuit.

The effect is measured by a thermoviewer (JEOL Ltd.
TG-5200). As an evaluation method, the heat-insulating support member 15 adhered the heating body by the above-described method, applied 800 W of electric power to the heating body 18, and controlled the temperature to 200 ° C. by the thermistor 16.

FIG. 11 shows the result of measuring the temperature change from the surface of the ceramic substrate 17 with the lapse of time 30 seconds after the power was turned on.

FIG. 11 shows a temperature change a in the area 34 bonded with the high thermal conductive adhesive and a temperature change b in the area 35 bonded with the normal thermal conductive adhesive. It can be seen that there is an opening of about 30 ° C. It can also be seen that the difference narrows over time.

FIG. 12 shows a similar configuration, in which the pressure roller 10 is brought into contact, and the temperature when the recording material 8 is actually passed is set by setting a thermocouple on the back surface of the ceramic substrate 17. Is shown.

The rising curve of the region 34 is c and the region 3
The rising curve of No. 5 is d. From FIG. 12, it can be seen that the rise of the curve c is slower than the rise of the curve d. However, during the actual fixing operation, the temperature difference is reduced, and there is no large difference in the fixability between the region 34 and the region 35. Recognize.

From this, by adhering the back surface of the ceramic substrate 17 to the heat insulating support member 15 as described above,
Even if abnormal temperature rise during runaway occurs, thermistor 16
In addition, the temperature rise in the area 34 on the thermistor electrode pattern 32 side is lower than that in the area 35 having only the heating element pattern due to the high thermal conductive adhesive and the like, and is positive in the area 35 as long as the fixing property of the recording material 8 is not affected. It has a strength enough to break only when the temperature rises abnormally, and it is possible to limit the damage position.

(Second Embodiment) In the second embodiment,
As shown in FIG. 7 (b), a circular projection having a diameter of 5 mm is formed on the heating element mounting surface of the heating element finger support portion 24, and the projection is adhered to the heating element to actively release heat. In a predetermined area where the thermistor 16 and the thermistor electrode pattern 32 are present, the distance between the circular projections is increased as a dispersing means, and the circular projections are sparsely provided in a place where heat is stopped, that is, in an area which is actively damaged during runaway. It is assumed that there is a configuration to arrange them. The description of the same components as those of the first embodiment is omitted.

Therefore, the entire area of the heat insulating support member 15 where the heating element is installed is formed in a counterbore so that heat does not escape at all locations. When this case was observed with a thermoviewer, heating spots and heating spots in the longitudinal direction were hardly observed on the heating surface of the heating body.

In response to this result, circular protrusions are densely arranged as dispersion means on the side (region 36) where the thermistor 16 and the thermistor electrode pattern 32 are located. Conversely, on the side where the thermistor 16 and the thermistor electrode pattern 32 are not installed (region 37), circular projections are sparsely arranged, and especially in places where the temperature is high, no thermal singularity is formed during runaway. Form.

As a result, similar to the first embodiment, it has strength enough to break only when the temperature is abnormally raised, and it is possible to limit the broken position.

In the method of forming the circular projections, a high heat conductive adhesive is used as the adhesive on the side where the thermistor 16 and the thermistor electrode pattern 32 are provided, while the low heat conductive adhesive is used on the side without the thermistor 16 and the like. It is effective to use a conductive adhesive.

Further, when the circular projections are densely and sparsely arranged as described above, the present invention can be applied to a higher-speed image forming apparatus as compared with the method in which heat is taken away from the entire surface on one side as in the first embodiment. However, it is possible to eliminate the difference in fixing property in the longitudinal direction.

(Third Embodiment) In the third embodiment, as shown in FIG. 8, a notch 35 'is formed in a part of the region of the heater support 24 that does not include the thermistor 16 and the thermistor electrode pattern 32. The ceramic substrate 1
7 is characterized in that the escape of heat is reduced as much as possible, all other predetermined areas are adhered to disperse the heat, and the rate of temperature rise at the time of abnormality is increased only in the notch 35 '. The description of the same components as those of the first embodiment is omitted.

In this embodiment, a high heat conductive silicone adhesive (manufactured by Dow Corning Toray Silicone Co., Ltd .: SE44) is used as a dispersing means on the entire surface except for the notch 35 '.
50, and a thermal conductivity of 1.88 w / (m × k)), and the effect is measured by a thermoviewer (JTG-5, JEOL Ltd.).
200).

As an evaluation method, a heating element was adhered to the heating element support 24 by the above-described method, and 8
Turn on the power of 00W and use thermistor 16
When the temperature rise is compared with that in the first embodiment, the temperature at the place where the high thermal conductive adhesive is adhered and the notch 35 ′ are 4 ° when the temperature rises.
There is an opening of about 0 ° C., and the temperature difference narrows over time as in the first embodiment.

For this reason, the heat insulating support member 15 is partially provided with a notch, and the heat of the notch is transferred to the ceramic substrate 1.
7 causes a difference in the temperature difference and the speed of the rise, and as a result, it is broken at the notch 35 'due to abnormal temperature rise during runaway.

As a result, even if an abnormal temperature rise during runaway occurs, it is possible to divide the notch 35 '.
It has strength enough to break only when the temperature is abnormally raised, and it is possible to limit the damage position.

It is more effective to bond the other area where the notch 35 'is not formed with an adhesive having good thermal conductivity as in the first or second embodiment.

(Fourth Embodiment) In the fourth embodiment,
As a reinforcing means, a method is adopted in which a high heat conductive member is applied to the non-heating surface of the heating body to improve the strength of the heating body itself in a predetermined area, thereby identifying a damaged portion of the heating body during runaway. The description of the same components as those of the first embodiment is omitted.

When the heating element alone is energized to control the temperature, the heating element itself pulsates and swings in the same manner as the control ON / OFF. When the input power is gradually increased, the pulsating strength also gradually increases, and the heating element is damaged with a certain amount of power. The location of the damage was damaged from various places.

Therefore, in this embodiment, as shown in FIG. 9, the effect was confirmed by coating glass 38 as a reinforcing means on the back surface of the heating element.

As a result, breakage certainly occurred at the coated portion, but the frequency was very low, and the effect was sufficiently obtained even with glass. Further, as a reinforcing means, coating was performed with a conductive resin paint having good thermal conductivity. In the case of coating with this conductive resin paint, once-coating or double-coating had little effect, and the coated portion was damaged at the same rate as the uncoated one.

However, as the amount of application is increased in three coats, four coats, and five coats, cracking in the applied area is reduced in proportion to the applied amount. In order to find the same effect as the glass coat, it was necessary to apply the conductive resin material four times or more. FIG. 13 shows the above results.

Then, a runaway test was performed by actually adhering to the heat insulating support member 15. The heat-insulating support member 15 in this case uses a conventional circular shaped bonding point arranged at equal intervals so that the difference from the conventional product is clarified, and the coating was performed using glass this time. .

As a result, only a small number (three out of 20) of the coatings was damaged in the coating application area, and most of them were damaged in the non-application area.

However, if the breakage occurs near the heating element contact 29 in this installation test, the impact sound at the time of damage is quite loud, and even if it is incorporated in an actual machine, the impact sound cannot be prevented.

Therefore, as a result of this examination, if the area where the impact sound at the time of damage is not a problem is an area 15 mm or more away from the end of the heating element as shown in FIG. Then, the heating element 15 mm from the end of the ceramic substrate 17 on the heating element contact 29 side shown in FIG.
Was coated with glass in the same manner as the thermistor 16 and the thermistor electrode pattern 32 side (application region 39).

As a result, there was no impact sound at the time of breakage, and breakage could be caused in the non-coating area in the same manner as in the first embodiment or the second embodiment.

From this, by applying the coating, the substrate strength of the application area itself can be increased and a difference in strength can be generated from the non-application area, thereby having a strength enough to break only at abnormal temperature rise. The damage position can be limited.

(Fifth Embodiment) In the fifth embodiment,
As a reinforcing means, the range of the high heat conductive material applied to the non-heating surface of the heating body is further expanded than that of the fourth embodiment, and conversely, the non-application area is narrowed to within 10 mm, and only this area is broken. The description of the same components as those of the first embodiment is omitted.

As shown in FIG. 10, the back surface of the heating body is coated with glass so as to cover the thermistor 16 and the thermistor electrode pattern 32 in the same manner as in the fourth embodiment (application area 40). Then, the application area is expanded from the center of the substrate to the vicinity of the center of the non-application area in the fourth embodiment (application area 4).
0 ′) Also, the application area 39 on the side of the heating element contact 29 is expanded to the vicinity of the center of the non-application area in the fourth embodiment, similarly to the thermistor 16 and the thermistor electrode pattern 32 side ( Application area 39 ').

In this case, the two application areas 39 'and the application area 40 are prevented from being connected to each other, the gap is narrowed from 60 mm, and the narrowest range in which breakage occurs in this area is confirmed. Although the breakage occurred in the non-applied area, if the area was reduced to 40 mm or less, the area would be damaged in the applied area, and the breakage position could not be controlled.

This is because the application area occupies the majority in the longitudinal direction of the substrate, and it is difficult to form a thermal singular point.

Therefore, the heat insulating support member 15 provided with the dispersing means used in the second embodiment is continuously used for 40 m.
m, a runaway test was attempted. As a result, as shown in FIG. 15, the thinnest non-applied area was 5 mm for surely breaking the non-applied area.

An experiment was also conducted to determine whether or not damage would occur from the uncoated area by moving the uncoated area 41 left and right. As a result, in a region where the counterbore of the heat insulating support member 15 is not provided with the circular protrusion, if it is about 20 mm or more from each of the protrusions at both ends, it has strength enough to be broken only at abnormal temperature rise during runaway, The damage position can be limited.

[0094]

According to the present invention, a dispersing means for dispersing heat is provided in a predetermined region of a substrate where a temperature detecting means is present, and a weak point such that a heating element is damaged during a normal operation is not provided on the substrate.
At the time of abnormal temperature rise, it is possible to limit the position and breakage in a predetermined area where the temperature detecting means exists, in accordance with safety standards, as in the conventional case, without breaking. Therefore, it is possible to limit the broken position at the time of abnormal temperature rise, and it is possible to provide a heating member having strength and excellent reliability at normal times.

Further, since the reinforcing means for reinforcing the substrate is provided in the predetermined area, it is possible to limit the position so as not to be damaged in the predetermined area and to break it by the thermal expansion by reinforcing the predetermined area, thereby increasing the strength. Can have.

Since the dispersing means and the reinforcing means are provided, the difference in strength between the predetermined area and the area to be damaged can be made clearer.

Since the area to be damaged on the mounting surface of the heater supporting portion to be bonded to the heater is bonded with an adhesive having a high thermal conductivity, the heat of the heater can be dispersed.

[0098] Since the predetermined area is densely provided in the predetermined area, the heat of the heating body can be dispersed.

Since the heating element and the heating element support are in contact with each other in the predetermined area, the heat of the heating element can be dispersed to the heating element support.

Since the reinforcing means is a coating covering a predetermined area, it is possible to limit a position where the substrate is damaged without forming a weak point on the substrate.

Since the coating is performed by applying a high heat conductive member to a predetermined area, the strength of the predetermined area can be increased.

Since the high thermal conductive member is made of glass, the strength of a predetermined region can be increased.

Since the high thermal conductive member is made of a conductive resin paint, the strength of a predetermined area can be increased.

Further, a heat fixing device of the present invention includes the above-mentioned heating element, a fixing film heated by the heating element, and a pressing member for pressing the fixing film against the heating element. Since the unfixed image on the recording material conveyed between the pressure member is fixed, the heating element is damaged by limiting the position when the temperature of the heating element abnormally rises, and can have higher strength during normal operation. .

Further, the image forming apparatus of the present invention has an image forming means for forming an unfixed image on a recording material and the above-mentioned heat fixing device, and fixes the unfixed image on the recording material. In addition, it is possible to prevent abnormal temperature rise and to improve the strength and reliability.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional configuration diagram illustrating a heat fixing device according to the first embodiment of the present invention.

FIG. 3 is a side view showing a heat insulating support member according to the first embodiment of the present invention.

FIG. 4A is a plan view showing a heating body support, and FIG. 4B is a cross-sectional view showing a heating body support.

FIG. 5 is a diagram showing a heating body surface according to the first embodiment of the present invention.

FIG. 6A is a diagram showing a heating element back surface according to the first embodiment of the present invention, and FIG. 6B is a drawing showing a heating element support portion according to the first embodiment of the present invention. FIG.

FIG. 7A is a diagram showing a heating element back surface according to a second embodiment of the present invention, and FIG. 7B is a drawing showing a heating element support portion according to the second embodiment of the present invention. FIG.

FIG. 8A is a view showing a heating element back surface according to a third embodiment of the present invention, and FIG. 8B is a drawing showing a heating element support portion according to the third embodiment of the present invention. FIG.

FIG. 9 is a view showing a heating body rear surface according to a fourth embodiment of the present invention.

FIG. 10A is a view showing a heating element back surface according to a fifth embodiment of the present invention, and FIG. 10B is a drawing showing a heating element support portion according to the fifth embodiment of the present invention. FIG.

FIG. 11 shows regions 34 and 35 on the surface of the heating element.
FIG. 5 is a diagram showing a temperature change of FIG.

FIG. 12 shows a region 34 and a region 35 on the back surface of the heating element.
FIG. 5 is a diagram showing a temperature change of FIG.

FIG. 13 is a diagram showing the number of times of application of a conductive resin and the number of times of breakage.

FIG. 14 is a diagram showing an application range from an end of a heating element and an impact sound at breakage.

FIG. 15 is a diagram illustrating a width of an uncoated area and damage in the uncoated area.

FIG. 16 is a cross-sectional configuration diagram illustrating a heat fixing device according to the related art.

FIG. 17 is a side view showing a heat insulating support member according to the related art.

FIG. 18A is a plan view showing a heating body support according to the related art, and FIG. 18B is a cross-sectional view showing a heating body support according to the related art.

FIG. 19 (a) is a diagram showing a heating element surface according to the related art, and FIG. 19 (b) is a diagram showing a heating element back surface according to the related art.

[Explanation of symbols]

REFERENCE SIGNS LIST 7 heating fixing device 8 recording material 10 pressure roller 14 fixing film 15 heat insulating support member 16 thermistor 17 ceramic substrate 18 heating element 24 heating element support section 29 heating element contact 30 thermistor electrode pattern contact 32 thermistor electrode pattern 34 thermistor and thermistor electrode pattern Side area 35 Area not containing the other side thermistor and thermistor electrode pattern 35 'Notch 36 Area on the side of the thermistor and thermistor electrode pattern 37 Area not containing the other side thermistor and thermistor electrode pattern 38 Coating area 39 Coating area 40 Coating area 41 Non-coating area

Claims (12)

[Claims] 1. A heating element comprising: a heating element which generates heat by energization on a surface of a substrate; and a temperature detecting means for detecting a temperature of the substrate on a back surface of the substrate, wherein heat is applied to a predetermined area where the temperature detecting means exists. A heating element comprising a dispersing means for dispersing. 2. A heating element comprising: a heating element that generates heat by energization on a surface of a substrate; and a temperature detection unit for detecting a temperature of the substrate on a back surface of the substrate. A heating element comprising a reinforcing means for reinforcing. 3. A heating element comprising a heating element which generates heat by energization on the surface of the substrate and a temperature detecting means for detecting the temperature of the substrate on the back surface of the substrate, wherein heat is applied to a predetermined area where the temperature detecting means is present. A heating element comprising a dispersing means for dispersing and a reinforcing means for reinforcing a substrate. 4. The dispersing means is characterized in that the predetermined area of the mounting surface of the heating element supporting portion that supports the heating element and the heating element is attached with an adhesive having a higher thermal conductivity than the other area. The heating element according to claim 1 or 3, wherein 5. The dispersing means according to claim 1, wherein the predetermined area is densely provided, and the other area is sparsely provided, with an interval between the bonding points on the mounting surface. Heating body. 6. The dispersing means is provided by abutting the heating element and the heating element support, and the other area is provided with a notch in which the heating element and the heating element support are not in contact. The heating element according to claim 1 or 3, wherein: 7. The heating element according to claim 2, wherein the reinforcing means is a coating covering the predetermined area so as to increase strength. 8. The heating element according to claim 7, wherein the coating applies a highly heat conductive member. 9. The heating element according to claim 8, wherein the high thermal conductive member is made of glass. 10. The heating element according to claim 8, wherein the high thermal conductive member is made of a conductive resin paint. 11. A heating member according to claim 1, comprising: a fixing film heated by the heating member; and a pressing member for pressing the fixing film against the heating member. A heat fixing device for fixing an unfixed image on a recording material conveyed between a fixing film and a pressure member. 12. An image forming apparatus comprising: an image forming means for forming an unfixed image on a recording material; and the heat fixing device according to claim 11.