JP2001085140A - Heating element, fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating element capable of saving energy by reducing preheating time and power consumption, a fixing device, and an image forming device. SOLUTION: This fixing device (heating device) includes a fixing film (heat resistant film) 103, a heating element 102 and a heating element supporting member 101 for holding them. The heating element 102 of the fixing device has a ceramic substrate 130, and a resistance heating element 132 and a conducting pattern provided on at least one side of the ceramic substrate 130. A heat insulating layer 139 containing hollow spheres is provided on the surface of the ceramic substrate 130 making contact with the heating element supporting member 101.

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 an electrophotographic process, such as a copying machine, a laser printer, a facsimile, and the like, a fixing device provided therein, and a heating element provided in the fixing device.

[0002]

2. Description of the Related Art A conventional image forming apparatus using an electrophotographic process is configured, for example, as shown in FIG.

FIG. 6 is a sectional view of a conventional image forming apparatus. In FIG. 6, reference numeral 1 denotes a photosensitive drum, 2 denotes a charging roller, 3 denotes a laser exposure device, 4 denotes a reflection mirror, 5 denotes a developing sleeve, and 6 denotes a developing sleeve. Is a toner, 7 is a toner container, 8 is a transfer roller, 9 is a recording material as a recording medium, 10 is a cleaning blade, 11 is a waste toner container, 12 is a fixing device, 1
3 is a paper cassette, 14 is a paper feed roller, 15 is a separation pad, and 16 is a high voltage power supply.

[0004] The photosensitive drum 1 rotates in the direction of the arrow shown in the figure, and is uniformly charged by the charging roller 2 supplied with power from the high voltage power supply 16. And the laser exposure device 3
Is reflected by the reflection mirror 4 and irradiates the photosensitive drum 1 to form an electrostatic latent image on the photosensitive drum 1.

The toner container 7 is filled with the toner 6. The photosensitive drum 1 is charged after an appropriate amount of the toner 6 is appropriately charged with the rotation of the developing sleeve 5.
Is supplied above. Then, the toner 6 on the developing sleeve 5 adheres to the electrostatic latent image on the photosensitive drum 1, and the electrostatic latent image is developed and visualized as a toner image.

On the other hand, the paper feed roller 14 feeds the recording materials 9 one by one from the paper cassette 13 at an appropriate timing. Here, the separation pad 15 is arranged in contact with the paper feed roller 14, and its surface friction coefficient, contact angle, and shape are adjusted so that only one recording material 9 is fed for each paper feed. I have.

The visualized toner image on the photosensitive drum 1 is transferred onto a recording material 9 by a transfer roller 8,
The recording material 9 to which the toner image has been transferred is conveyed to the fixing device 12, heated and pressed to fix the toner image, and then discharged outside the apparatus. The transfer residual toner remaining on the photosensitive drum 1 without being transferred is scraped off by the cleaning blade 10 so that the waste toner container 1
1, the photosensitive drum 1 whose surface has been cleaned
Are repeatedly subjected to the next image forming process.

As the fixing device 12, a heating element is constituted by providing a pattern of a resistance heating element on a ceramic substrate, and the heating element generates heat to heat the object to be heated via a thin film. A method using a method is known (see Japanese Patent Application Laid-Open No. 63-313182).

However, in the above-described film heating method, a large twisting force is generated in the endless belt-like film.
As a countermeasure for this, a method of reducing the twisting force of the film by driving the endless film with a sufficient margin and reducing the driving torque has been put to practical use (JP-A-4-44057, JP-A-4-44057). 4-44
No. 077).

FIG. 7 shows an example of such a film fixing device.
Shown in

FIG. 7 is a cross-sectional view of a conventional film fixing device. In FIG. 7, reference numeral 102 denotes a heating element. The heating element 102 has a heating element 108 formed on a ceramic substrate.
A glass layer 109 is coated thereon as a protective layer. A thermistor 1 is provided on the back surface of the heating element 102.
07 is mounted, and the temperature of the heating body 102 is detected by the thermistor 107. And the heating element 10
8 is heated by being supplied with power from a power source (not shown) and generates heat so that the temperature detected by the thermistor 107 becomes constant.
The triac 111 is driven by U110 to control the amount of supplied power.

Reference numeral 103 denotes an endless fixing film. The fixing film 103 is a cylindrical heat-resistant film having a three-layer structure. The innermost layer is a base layer. This layer is responsible for mechanical properties such as torsional strength and smoothness of the fixing film 103, and is made of polyimide, polyamideimide, PEEK, PES, PPS
And the like. The next layer is a conductive primer layer, which is a conductive layer in which conductive particles such as carbon black are dispersed, and also serves as an adhesive for bonding the third layer and the base layer. The outermost layer is a top layer, and the resistance and thickness of the top layer are optimally set so as not to cause various image defects.

Reference numeral 101 denotes a heating member supporting member for supporting the heating member 102, which is formed of a resin having high heat resistance such as PPS, liquid crystal polymer, etc., and also serves as a guide member for promoting smooth rotation of the fixing film 103. Function. Also, 106
Is a fixing stay made of a metal such as iron or aluminum.
Of the heating element supporting member 101
Plays a role in increasing the rigidity of the

Reference numeral 104 denotes a heating roller, which is constituted by covering a core metal 104a made of aluminum, cast iron, or the like with an elastic body 104b having high heat resistance such as silicon rubber, and the surface of which has a releasability from toner. High PFA, PTFE, F
A film of a fluororesin such as EP is formed.

The pressure roller 104 is used to fix the fixing film 10.
3, the heating member 102 is pressed against the heating member 102, and a fixing nip N is formed at the contact portion. Then, the pressure roller 10
4 is rotated and the fixing film 10 is rotated.
Reference numeral 3 is driven to rotate in the fixing nip portion N.

The recording material P carrying the toner T is conveyed by a transfer roller and a photosensitive drum (not shown) and guided to a fixing nip N by a fixing entrance guide 105. Then, the toner T on the recording material P is pressed and heated on the recording material P at the fixing nip N, and the toner resin is softened so that the toner T adheres to the recording material P and is permanently fixed. .

Since a fixing device employing such a film heating method can use a heating element (heater) having a low heat capacity, the wait time can be reduced (quick start) as compared with the conventional heat roller method. Becomes Further, since the quick start becomes possible, the residual heat at the time of the non-printing operation becomes unnecessary, and the power saving can be achieved comprehensively.

[0018]

However, there has been a demand for further energy savings due to the growing interest in environmental issues in recent years, and even in an electrophotographic printer having a fixing device employing a film heating method, power consumption is low. Is consumed by the fixing device, and the amount of consumption is a problem. For this reason, even in a fixing device employing a film heating method, there is a demand for power saving by further improving thermal efficiency.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a heating element, a fixing device, and an image forming apparatus capable of shortening preheating time, reducing power consumption and realizing energy saving. It is to provide a device.

[0020]

In order to achieve the above object, the invention according to claim 1 is characterized in that the heating element of the heating device provided with a heat resistant film, a heating element and a heating element supporting member for holding the same. A ceramic substrate, comprising a resistance heating element and a conductive pattern provided on at least one surface of the ceramic substrate, and a heat insulating layer containing a hollow sphere provided on a surface of the ceramic substrate in contact with the heating element support member. It is characterized by having done.

According to a second aspect of the present invention, in the first aspect of the present invention, the thickness of the heat insulating layer is 10 μm or more and 500 μm or less.
μm or less.

According to a third aspect of the present invention, in the first or second aspect of the invention, the outer wall of the hollow sphere constituting the heat insulating layer is made of glass.

According to a fourth aspect of the present invention, there is provided a heating apparatus comprising a heat-resistant film, a heating element and a heating element supporting member for holding the heat-resistant film and the heating element, wherein the heating element comprises a ceramic substrate and at least one surface of the ceramic substrate. It has a provided resistance heating element and a conductive pattern, a thermistor is provided by printing on a surface of the ceramic substrate that is in contact with the heating element support member, and at least on a surface of the ceramic substrate that is in contact with the heating element support member, A heat insulating layer containing a hollow sphere is provided in a region including the thermistor.

According to a fifth aspect of the present invention, in the fourth aspect of the invention, the thickness of the heat insulating layer is 10 μm or more and 500 μm or less.
μm or less.

According to a sixth aspect of the present invention, in the fourth or fifth aspect of the invention, the outer wall of the hollow sphere constituting the heat insulating layer is made of glass.

According to a seventh aspect of the present invention, there is provided a fixing device including the heating element according to the first to fifth or sixth aspects.

According to an eighth aspect of the present invention, there is provided an image forming apparatus including the fixing device according to the seventh aspect.

[0028]

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

<Embodiment 1> Here, a heating element 102 (see FIGS. 1 and 2) according to the present invention will be described in comparison with a conventional heating element 102 'shown in FIG.

First, the structure of a conventional heating element 102 'is shown in FIG.
It will be described based on. FIG. 3A shows a conventional heating element 1.
FIG. 2B is a plan view of the heating element 102 ′, and FIG.

In FIG. 3, 130 'is 6.7 mm wide,
This is a heater substrate having a length of 270 mm.
Reference numeral 30 'is made of a ceramic having good thermal conductivity, such as alumina or aluminum nitride. The surface thereof is in contact with a fixing film (not shown), and the back surface is fixed and supported by a heating member support member (not shown). Then, a recording material (not shown) is conveyed in a direction intersecting the longitudinal direction of the heater substrate 130 '.

Reference numerals 131 ', 134', and 135 'denote conductive electrodes, which are formed by screen-printing a paste-like conductive material in which Ag, Pd, or the like is dispersed on the heater substrate 130' and passing through a firing step. It is formed.

Further, 133 'is a glass coat layer,
The glass coat layer 133 'covers a part of the resistance heating element 132' and the conductive electrode 131 ', and is provided for protecting the surface, improving slidability with the fixing film, and ensuring dielectric strength. The conductive electrode 131 'is an AC electrode serving as a contact point with a connector (not shown), to which a commercial power supply voltage is applied. Reference numeral 134 'denotes a DC electrode, in which a through hole (not shown) called a through hole is formed. The DC electrode 134' is electrically connected to an electrode 135 'on the back surface of the heater substrate 130'. I have. And the electrode 13
5 'is connected to the thermistor 136'.

The thermistor 136 'is a heater temperature detecting element, and the temperature of the heating element 102' is detected by measuring the resistance value of the thermistor 136 'by a CPU (not shown). Is controlled by the wave number control or the phase control so that is constant. Note that the thermistor 136 'is disposed in the paper passage portion of the narrowest recording material that can pass paper.

The resistance heating element 132 'has a width of 1 mm and a length of 220 mm.
Reference numeral 32 ′ denotes a paste-like electric resistor in which a conductive material such as Ag or Pd and a non-conductive material such as glass are dispersed.
It is formed by screen printing 0 'and passing through a baking process.

FIG. 1 shows a heating element 102 according to Embodiment 1 of the present invention.

FIG. 1A shows a heating element 1 according to the present embodiment.
FIG. 2B is a plan view of the heating element 102, and FIG. 2B is a rear view of the heating element 102. In the drawing, 130 is a ceramic substrate having a width of 6.7 mm and a length of 270 mm, 131 is an AC electrode, 133 is a glass coat layer, 134 Denotes a DC electrode, 132 denotes a heating element having a thickness of 10 μm, a width of 1 mm, and a length of 110 mm.
32 are arranged in parallel, and both are electrically connected in series, and the total resistance value is set to 25Ω.

Reference numeral 134 denotes a DC electrode, in which a through hole (not shown) called a through hole is formed. The DC electrode 134 is electrically connected to the electrode 135 on the back surface of the ceramic substrate 130, and 135 is a thermistor 136
Is connected to. Reference numeral 139 denotes a heat insulating layer. The heat insulating layer 139 is a glass layer in which hollow glass spheres are dispersed, and is provided in a region that almost covers the heat generating body 132 on the opposite surface.

Thus, the heating element 102 according to the present invention configured as described above is manufactured as follows.

That is, first, a heating element 132 having a thickness of 10 μm is formed by screen printing on a ceramic substrate 130 mainly composed of alumina or aluminum nitride, and after drying and firing, the conductive electrode 134 on the heating element 132 side and the conductive electrode 134 on the back side are formed. Electrode 135 is similarly formed with a thickness of 10 μm.

Next, the glass coat layer 133 and the heat insulating layer 1
39 is formed with a thickness of 50 μm by screen printing, and then dried and fired. At this time, the heat insulating layer 139 has a pattern in which holes are formed so as not to cover about 2 mm around the area where the thermistor 136 is mounted.

Finally, a thermistor 1 is formed using a conductive adhesive.
36 is fixed on the electrode 135 by bonding.
6 is strongly bonded to the ceramic substrate 130 with an insulating heat-resistant adhesive. The glass paste of the heat insulating layer 139 contains 10 parts by weight of glass bubbles S60 manufactured by Sumitomo 3M. Although the thermal conductivity of only the base glass paste after firing is 2 W / mK, when the hollow glass is dispersed, many fine air holes are formed in the glass layer. It can be reduced to 0.7 W / mK. Other examples of such an effect that can be obtained include Karoon manufactured by Nippon Sheet Glass Co., Ltd. and Q-Q manufactured by Asahi Glass Co., Ltd.
There are hollow glass spheres such as CEL. It is also possible to form a heat-insulating layer similarly by mixing and coating a small hollow sphere such as a phenol balloon, an epoxy balloon, and a shirasu balloon with a high heat-resistant resin material such as a polyimide. Since the thermal conductivity of the heat insulating layer increases due to the deformation and the heat insulating effect decreases, a hollow sphere made of glass having high rigidity is preferable.

The diameter of the hollow glass sphere is several μm.
Those having a diameter of several hundred μm and having a small diameter have a relatively small volume ratio of the contained air, and the heat insulation effect is reduced. On the other hand, a film having a large diameter has a high heat insulating effect, but tends to become a non-uniform film due to a large surface unevenness when the film is formed. At least 1 for insulation effect
A film thickness of 0 μm or more is required, and the larger the film thickness, the more effective. However, in order to produce a film with less surface irregularities, a film thickness of 500 μm or less at the maximum is preferable.

FIG. 2 shows a cross section of the fixing device according to the present invention.

In FIG. 2, reference numeral 101 denotes a heating element supporting member, which holds a heating element 102 having the structure shown in FIG. Note that the configuration of the heating element 102 is as shown in FIG. 1, and thus the description thereof will not be repeated, and in FIG. 2, the same elements as those shown in FIG.

As shown, the heating element 102 is a heat insulating layer 13.
9 is supported so as to face the heater supporting member 101 side. In the heating element 102, the heating element 13
When power is supplied to the heating element 2, the heating element 132 generates heat. However, since the ceramic substrate 130 is made of ceramic having good thermal conductivity, the temperature of the ceramic substrate 130 rises while maintaining substantially the same temperature as the heating element 132.

In the conventional heating element 102 'shown in FIG. 3, a metal electrode 13 having good heat conductivity is directly or directly attached to the heating element supporting member.
Since the heater substrate 130 ′ is in contact with the heater 5 ′ through the heater 5 ′, a large amount of heat is transmitted to the heater supporting member, and the temperature of the heater 102 ′ is gradually increased. By providing the heat insulating layer 139 in the body 102, the amount of heat transmitted to the heating body supporting member 101 can be reduced, and the temperature of the heating body 102 can be increased at the same input power. Then, when the temperature of the heating element 102 rises quickly, the target temperature is quickly reached, so that the power can be quickly reduced and the energy consumption can be suppressed.

When the set temperature is maintained, for example, during paper passing, the amount of heat escaping to the heating member supporting member 101 is reduced.
Energy consumption during normal use can be reduced. Specifically, the conventional heating element 102 'shown in FIG. 3 is used for the fixing device shown in FIG.
/ Sec at a temperature of 15 ° C and a humidity of 10%
02 'was started with 400 W of electric power, it took 7 seconds for the heating element temperature to reach 190 ° C. However, when the heating element 102 according to the present embodiment shown in FIG.
The temperature reached 190 ° C. in seconds. Further, when the recording material P is rushed 11 seconds after the start of energization, the average power used until immediately before the recording material P is rushed is 37% in the conventional heating element 102 '.
In the heating element 102 according to the present embodiment, the power can be reduced to 340 W.

Further, the average power consumption during paper passing is 320 W for the conventional heating element 102 ′, and the heating element 1 according to the present embodiment has an average power consumption of 320 W.
02 is 300 W, so that power consumption can be reduced both at startup and during paper passing.

In this embodiment, the case where the heat insulating layer is provided on almost the entire back surface of the heater is described. However, when the heat insulating layer is thicker than the electrode, the electrode is used to reduce the amount of material used. Even if an air layer is provided between the heating body and the heating body support member by scattering the heat insulation layer avoiding the pattern portion, there is a heat insulation effect, but water vapor generated when the recording material passes through is heated. And flows into the gap between the heating element supporting member and dew on the heating element supporting member. Then, when the dew condensation grows, the high temperature substrate and the water droplets come into direct contact with each other to remove heat, so that the heat insulating effect is weakened. Therefore, it is preferable to provide the heat insulating layer concentrated in the paper passing area.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 4A shows a heating element 1 according to the present embodiment.
FIG. 2B is a plan view of the heating element 102, and FIG. 2B is a rear view of the heating element 102. In the figure, reference numeral 130 denotes a ceramic substrate, which is 270 mm long, 0.6 mm thick,
It is made of a material having a thermal conductivity of 30 W / mK or more mainly composed of aluminum nitride having a width of 6.7 mm.

Reference numeral 132 denotes a thickness of 10 μm and a width of 1.5 m
A heating element 131 having a length of 220 mm and a length of 220 mm is an AC electrode. The AC electrode 131 is a contact point with an AC connector (not shown) and is connected to the heating element 132. Reference numeral 133 denotes a glass coat layer having a thickness of 50 μm. The glass coat layer 133 covers the heating element 132 and a part of the electrode 131, and improves the slidability with a fixing film (not shown) and ensures insulation heat resistance. ing.

As shown in FIG. 4B, a thermistor 140 is provided on the back surface of the ceramic substrate 130 which is in contact with the heating element support member, within the minimum size paper passing area. The thermistor 140 is formed by patterning and sintering a paste material having thermistor characteristics on the ceramic substrate 130 by screen printing. The thermistor 140 is provided with a DC electrode 135,
4 through a through hole (not shown).
It is coupled to the DC power supply electrode 134 on the front side shown in FIG.

Thermistor 140 and DC electrode side power supply electrode 1
35 is covered with a heat insulating layer 139 having a thickness of about 50 μm. When the printing thermistor comes into contact with air, the resistance value changes with the lapse of time, so that a coated glass that blocks contact with air is required. The heat insulating layer 139 is formed by mixing a glass balloon with a glass paste, and has a good affinity between the glass balloon and the glass paste, so that they form a strong protective film.

Further, since the thermistor 140 is thermally cut off from the heating element supporting member, when the temperature of the heating element 132 changes, the delay in the transmission of the temperature is only the heat capacity of the ceramic substrate 130, whereby the response of the thermistor 140 is reduced. Becomes better. Due to this effect, there is a difference between the thermistor temperature and the temperature of the heating element in the related art even when a constant temperature control is performed, and the temperature ripple of the heating element is large. The difference is reduced and the temperature ripple is reduced. As a result, the fixing unevenness in the conveying direction of the recording material is reduced, and the variation in the fixing property is reduced.

Since the fixing temperature is set so that the place having the worst fixability is equal to or higher than a certain criterion, the difference between the place having the worst fixability and the place having the good fixation when the heating element 102 according to the present embodiment is used. And the fixing temperature could be lowered by 5 ° C. Thereby, the conventional heating element 10 shown in FIG.
2 ′, the heating element 102 ′ is heated at 400 ° C. under an environment of a temperature of 15 ° C. and a humidity of 10% at a roller feed speed of 50 mm / sec.
When starting with electric power of W, 320 W of electric power was required on average during paper passing.
With the power of 290 W on average, the same fixing property was obtained. As a result, the change in the temperature of the heating element during constant temperature control is reduced, the temperature control temperature is reduced by 5 ° C., and the amount of heat escaping to the heating element support member 101 is reduced, so that energy consumption can be reduced. became.

<Third Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a partial sectional view of a fixing device according to a third embodiment of the present invention. In FIG. 5, the same elements as those shown in FIG. 4 are denoted by the same reference numerals.

In this embodiment, a heat insulating layer 139 is provided on the surface of the heating element 102 on which the heating element 132 is provided, and this surface is used as a surface in contact with the heating element supporting member 101. The printing thermistor 136 is disposed on a surface that slides on the fixing film 103, and is covered with a glass coat layer 133 having a thickness of 10 μm.

Thus, in the present embodiment, the heating element 132
Is located on the back side of the heating element 102, the heat generated from the heating element 132 is
0, transmitted from the fixing film 103 to the recording material P via the glass coat layer 133 having a thickness of 10 μm. In general, the thermal conductivity of the glass coat layer 133 is about 2 W / mK, and the thermal conductivity of the aluminum nitride substrate 130 is about 200 W / mK.

A comparison of the heat transfer path from the heating element 132 as the heat source to the fixing film 103 between the conventional example and the present embodiment shows that the difference between the conventional example and the glass coat layer 133 ′ in the conventional example is four.
In the present embodiment, the thickness is 600 μm for the aluminum nitride substrate 130 with respect to 0 μm. Since the thermal conductivity of aluminum nitride is 100 times that of glass, the thermal resistance of this embodiment is about 1/6 in terms of thermal resistance. That is, the heating element 102 according to the present embodiment has a configuration in which heat is easily transmitted six times as compared with the conventional heating element 102 ′. In such a configuration, it is particularly effective to provide the heat insulating layer 139.

By directly providing the heat-insulating layer 139 having a low thermal conductivity at the portion where the temperature is the highest, the ratio of the amount of heat transmitted to the fixing film 103 to the amount of heat transmitted to the heater supporting member 101 (that is, thermal efficiency) is increased. Can be. Using a heating element in which a hollow sphere is not mixed in the heat insulating layer 139, at a roller feed speed of 50 mm / sec, at a temperature of 15 ° C.
When the heating element was started with 400 W power in an environment of 10% humidity, an average power of 300 W was required during paper passing. However, in the heating element 102 according to the present embodiment, the average power was 2 W.
Reduced to 50W. By directly providing the heat insulating layer 139 having a low thermal conductivity at the portion where the temperature is the highest, the amount of heat escaping to the heater supporting member 101 is reduced, and the amount of heat transmitted to the recording material P is increased, so that the energy consumption can be reduced. It became.

[0064]

As apparent from the above description, according to the present invention, since the heat-insulating layer containing the hollow sphere is provided on the surface of the ceramic substrate of the heating element which is in contact with the heating element supporting member, the preheating time of the heating element is reduced. And energy saving by reducing power consumption.

[Brief description of the drawings]

FIG. 1 is a plan view and a rear view of a heating element according to Embodiment 1 of the present invention.

FIG. 2 is a partial cross-sectional view of a heating element according to Embodiment 1 of the present invention and a fixing device including the same.

FIG. 3 is a plan view and a back view of a conventional heating element.

FIG. 4 is a plan view and a rear view of a heating element according to Embodiment 2 of the present invention.

FIG. 5 is a partial sectional view of a heating element according to Embodiment 3 of the present invention and a fixing device including the same.

FIG. 6 is a sectional view of a conventional image forming apparatus.

FIG. 7 is a sectional view of a conventional fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Heater support member 102 Heater 103 Fixing film (heat-resistant film) 130 Ceramic substrate 131 Electrode 132 Resistance heating element 133 Glass coat layer 134 Electrode 135 Electrode 136 Thermistor 139 Thermal insulation layer 140 Thermistor

Continuation of the front page (72) Inventor Hikaru Nagata 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H033 AA20 AA32 BA05 BA11 BA12 BA26 BA31 BA32 BE03 CA04 CA30 CA44 CA46 3K058 AA02 AA81 AA87 BA18 CA23 CA61 CA93 DA05

Claims (8)

[Claims] 1. A heating device of a heating apparatus comprising a heat-resistant film, a heating element, and a heating element supporting member for holding the heat-resistant film, a ceramic substrate, and a resistor provided on at least one surface of the ceramic substrate. A heating element comprising a heating element and a conductive pattern, wherein a heat insulating layer containing a hollow sphere is provided on a surface of the ceramic substrate in contact with the heating element support member. 2. The heat insulation layer has a thickness of 10 μm or more and 50 μm or more.
The heating element according to claim 1, wherein the heating element has a thickness of 0 µm or less. 3. The heating element according to claim 1, wherein the outer wall of the hollow sphere constituting the heat insulating layer is made of glass. 4. A heating element of a heating device comprising a heat-resistant film, a heating element and a heating element supporting member for holding the heat-resistant film, a ceramic substrate, and a resistor provided on at least one surface of the ceramic substrate. It has a heating element and a conductive pattern, is provided with a thermistor by printing on the surface of the ceramic substrate that is in contact with the heating element support member, and includes at least the thermistor on the surface of the ceramic substrate that is in contact with the heating element support member. A heating element comprising a heat insulating layer containing a hollow sphere provided in a region to be heated. 5. The heat insulation layer has a thickness of 10 μm or more and 50 μm or more.
The heating element according to claim 4, wherein the heating element has a thickness of 0 µm or less. 6. The heating element according to claim 4, wherein the outer wall of the hollow sphere constituting the heat insulating layer is made of glass. 7. A fixing device comprising the heating element according to claim 1. 8. An image forming apparatus comprising the fixing device according to claim 7.