JPH1184925A - Heating body, heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely crack the base plate of a heating body at an intended spot when temperature rises excessively and to improve safety by possessing the spot intended to crack the base plate when the temperature rises excessively and providing a base plate reinforcing member at an optional spot other than the intended spot in a heater equipped with a heating element on the base plate. SOLUTION: The heater 10 equipped with the heating element on the base plate 12 has the spot G intended to crack the base plate 12 when the temperature rises excessively and is provided with the base plate reinforcing member at the optional spot other than the spot G. Since a temperature peak is lower at the position of an H-line on the instant heat is generated excessively than at the position of a G-line, thermal stress is less at the position of the H-line than at the position of the G-line. While the refractive intensity of the base plate 12 is increased by a DC conductive pattern 24 and a protective layer 11b, a through-hole 27 exists in the vicinity of the position of the G-line, so that the refractive intensity is relatively made higher at the position of the H-line. Therefore, the base plate is surely cracked at the position of the G-line and the disconnection of a secondary circuit is prevented when the heat is generated excessively suddenly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating member for heating a material to be heated, a heating device provided with the heating member, and an image forming apparatus provided with the heating device as image heating means.

In particular, an image forming apparatus using an appropriate image forming process such as an electrophotographic process or an electrostatic recording process, and an image heating and fixing method in which a toner image (developing agent image) is thermally fixed to a member to be heated in the image forming apparatus. It is suitable for a heating device as a device and a heating element used in the heat fixing device.

[0003]

2. Description of the Related Art Conventionally, a heat roller system has been often used as a heating device in an image forming apparatus such as a copying machine or a printer. In this method, a recording material is fixed to a press nip (fixing nip) between a heating roller (fixing roller) maintained at a predetermined heating temperature by a built-in heat source such as a halogen heater and an elastic pressing roller pressed against the heating roller. And heats and fixes an unfixed image on the surface of the recording material by the heat of the heating roller.

However, in the heating device as the image heating fixing device of the heat roller type, the temperature of the heating roller must be constantly maintained at a high temperature so that an image can be output immediately at any time. In addition, the energy consumption is large, and heat is released into the machine even during standby, causing a problem of temperature rise in the machine. Also, a considerable waiting time is required from when the power is turned on to when the heating roller rises to a predetermined temperature suitable for heating the recording material as the material to be heated.

Recently, a heating apparatus of a film heating type has been proposed and put into practical use. This heating device has a method and configuration in which a material to be heated is closely attached to a heating body via a heat-resistant film, and the heating body and the heat-resistant film are relatively moved to give heat of the heating body to the material to be heated via the heat-resistant film. That is, it can be used as a means for heat-fixing an unfixed toner image as a permanently fixed image on the surface of a recording material carrying the image.

[0006] In such a film heating type heating apparatus, a heating element having a low heat capacity or a thin film having a high temperature rise can be used. Therefore, even if the recording material as the material to be heated is immediately passed, the heating member can be sufficiently heated to a predetermined temperature before the recording material reaches the fixing portion. And has the advantage that the temperature rise in the machine such as an image forming apparatus can be reduced,
It is effective.

FIG. 9A is a schematic cross-sectional view of an essential part of an example of a film heating type heating device (image heating fixing device). FIG. 9B is a partially cutaway plan view of the heating element.

Reference numeral 10 denotes a heating element, which includes a heater substrate 12, resistance heating elements (electric heating elements) patterns 13a and 13b formed on one side of the heater substrate 12, and conductive patterns 23 and 2.
The power supply electrode patterns 21 and 22 and the surface protection layer 11 which covers the resistance heating element patterns 13a and 13b.

The heater substrate 12 has a horizontally long and thin shape whose longitudinal direction is perpendicular to the conveying / moving direction A of the recording material P as a material to be heated, which will be described later. , Length 270mm, width 7mm, thickness 0.
It is a 635 mm ceramic substrate of heat resistance, electrical insulation and low heat capacity such as alumina.

The resistance heating element patterns 13a and 13b are made of, for example, an electric resistance material paste (resistance paste) such as silver palladium (Ag / Pb).
It is formed by applying and firing by screen printing or the like substantially in parallel with the length of the ceramic base material in the form of a narrow strip having a width of 1 mm and a width of 1 mm.

Two power supply electrode patterns 21 and 22 are provided side by side on one end side of the ceramic base material 12.

The resistance heating element patterns 13a and 13
b is connected to the two power supply electrode patterns 21 and 22
Are electrically connected to each other via the conductive pattern 23. The other ends of the resistance heating element pattern 13a and the resistance heating element pattern 13b are electrically connected to each other.

The conductive pattern 23 and the two power supply electrode patterns 21 and 22 are both formed by applying a pattern of a conductive material paste such as Ag on the surface of the ceramic base material 12 by screen printing or the like and firing it. .

The heating element 10 is connected to the resistance heating element pattern 1.
Exposure with the surface side on which 3a and 13b are formed facing downward,
The heating element holder (stay) 16 having rigidity and heat insulation properties is held and fixedly arranged.

The heating element 10 has a power supply electrode pattern 21.
22 is fed from a power supply circuit (not shown), and the resistance heating element patterns 13a and 13b are heated over their entire length to increase the temperature. The temperature rise is detected by the temperature detecting element 14, and the temperature detection information is not shown. The power supply to the resistance heating element patterns 13a and 13b is controlled so that the temperature of the heating element 10 is maintained at a predetermined temperature by being fed back to the temperature control circuit.

Reference numeral 15 denotes, for example, a thickness of 30 μm to 100 μm.
A heat-resistant film 17 made of polyimide or the like has a pressing roller 17 as a pressing member for pressing the heat-resistant film 15 against the surface protective layer 11 which is the film sliding surface of the heater 10.

The heat-resistant film 15 is
While being pressed against the heating body 10 by the
The surface of the heating element 10 (surface protection layer 11
Surface) and rotate.

Thus, the resistance heating element patterns 13a and 13b
The heating body 10 is heated to a predetermined temperature by energizing
Further, in a state where the heat-resistant film 15 is slid while being pressed against the heating member 10, a pressure-contact nip portion (fixing nip portion) between the heating member 10 formed with the heat-resistant film 15 interposed therebetween and the pressure roller 17. The recording material P to be image-fixed as a material to be heated is introduced between the heat-resistant film 15 of N and the pressure roller 17, and the fixing nip N is conveyed together with the heat-resistant film 15. The heat from the heating body 10 is applied to the recording material P via the heat-resistant film 15 to heat and fix the unfixed toner image T on the recording material P to the surface of the recording material P. The recording material P that has passed through the fixing nip N is transported separately from the surface of the heat-resistant film 15.

[0019]

However, in this method,
When excessive power is supplied, the temperature of a part of the heating element rises rapidly, causing a large temperature difference inside the ceramic substrate that is the substrate of the heating element, and applying thermal stress exceeding the substrate strength This has caused a problem that the heating element is damaged.

When the main body becomes uncontrollable, the ceramic base may be broken unspecified due to, for example, a triac failure or a defective thermal fuse. Only the energization pattern may be interrupted, and in the case of a temperature control circuit failure, it is erroneously recognized that the heating element has not warmed up yet, and it continues to supply power and overheats, causing smoke and the like from around the fuser. There was a case. In addition, the dielectric strength of the primary AC that promotes heat generation and the withstand voltage of the secondary DC that performs temperature detection cannot be satisfied, and sometimes the secondary circuit may be destroyed by current leaking to the main body.

Accordingly, an object of the present invention is to provide a heating element, a heating apparatus, and an image forming apparatus having improved safety as a configuration capable of surely breaking a heating element substrate at a point intended at an excessive temperature rise.

[0022]

[Means for Solving the Problems]

[1]: A heater provided with a heating element on a substrate, having a portion intended to crack the substrate at an excessively high temperature, and having a substrate reinforcing member at an arbitrary portion other than the portion. body.

[2]: A heating element in which a heating element is arranged on one side of the substrate such that the center of heat generation is shifted in the width direction with respect to the center of the substrate width within the substrate. A heating element, comprising: a substrate reinforcing member at an arbitrary position other than the above-mentioned position.

[3] The heating element according to claim 1, wherein a heating element is disposed on one side of the substrate and a temperature detecting member is disposed on the other side.

[4]: A place where the substrate is intended to be broken at the time of excessive temperature rise and a temperature detecting member are arranged at different positions, and a substrate reinforcing member is provided on the temperature detecting member side of the place. The heating body according to claim 3, wherein

[5] The heating element according to claim 3 or 4, wherein the electrode of the temperature detecting member is the substrate reinforcing member.

[6]: The heating element is folded back in the longitudinal direction in the substrate, an electrode of the heating element is provided at one end of the substrate in the longitudinal direction, and a portion intended to break the substrate when the temperature is excessively raised is set at the center of the substrate longitudinal direction. The heating element according to any one of claims 1 to 5, wherein the heating element is provided on the electrode side.

[7] The heating element according to claim 6, wherein an electrode of the temperature detecting member is disposed at an end of the substrate opposite to the electrode of the heating element.

[8]: The temperature detecting member has a conductive pattern formed on the substrate and a temperature detecting element connected to the conductive pattern, and the conductive pattern also serves as the substrate reinforcing member. The heating element according to claim 1, wherein the heating element is provided.

[0030]

[9] The heating element according to any one of claims 1 to 8, wherein the substrate is ceramic.

[10] The heating element according to any one of claims 1 to 9, wherein the portion intended to crack the substrate when the temperature is excessively raised is a through hole provided in the substrate. .

[11] The substrate reinforcing member has any one of strength, elasticity, ductility, plasticity, good thermal conductivity, good heat insulation and a combination thereof, which is higher than that of the substrate. 11. The heating element according to any one of 1 to 10.

[12] The heating element according to any one of claims 1 to 11, wherein the substrate reinforcing member is formed to have a width wider than the heating element in the substrate width direction.

[13] The heating according to any one of claims 1 to 12, wherein the substrate reinforcing member is formed to have an arbitrary width from 0.1 mm or more within the width of the substrate. body.

[14] The apparatus according to any one of claims 1 to 13, wherein the substrate reinforcing member is formed to have an arbitrary length from 1.0 mm or more in the longitudinal direction of the ceramic substrate. Heating body.

[15]: The substrate reinforcing member is 1.0 μm
The heating element according to any one of claims 1 to 14, wherein the heating element is formed with an arbitrary thickness.

[16] The substrate reinforcing member may have a plurality of portions on the back surface of the ceramic substrate by using a plurality of types of members having different physical properties. The heating element according to claim 1.

[17] A heating device comprising the heating element according to any one of claims 1 to 16 as a heating element for heating a material to be heated.

[18] A heating device in which a material to be heated is brought into close contact with a heating body through a heat-resistant film, and heat of the heating body is applied to the material to be heated through the heat-resistant film. A heating device comprising the heating element according to any one of 1 to 16.

[19]: A heat nip is formed by sandwiching a heat-resistant film between the heating element and the pressure roller, and a material to be heated is interposed between the heat-resistant film and the pressure roller in the heat nip. Is a heating device that heats the material to be heated by nipping and transporting the heating nip together with the heat-resistant film,
A heating device, wherein the heating element is the heating element according to claim 1.

[20] The apparatus according to claim 17, wherein the material to be heated is a recording medium carrying an unfixed image, and the apparatus is a device for thermally fixing the unfixed image to the recording medium. Heating equipment.

[21]: An image forming means for forming a developer image on a recording medium, and an image heating means for heating the developer image, wherein the image heating means according to claim 17 to 20. An image forming apparatus, which is the heating apparatus according to any one of the preceding claims.

<Function> By providing the substrate reinforcing member at any place other than the place where the substrate is intended to be broken at the time of excessive temperature rise, the strength of the place where the substrate reinforcing member is provided can be increased, Stress is suppressed, and the heating body substrate can be reliably broken at the intended location at the time of excessive temperature rise.

In particular, a point intended to break the substrate at the time of excessive temperature rise and a temperature detecting member are respectively arranged at different positions on the substrate, and a substrate reinforcing member is provided on the temperature detecting member side of the point. In addition, when the temperature is excessively raised, the heating substrate is prevented from being cracked at the position where the temperature detecting member is formed, thereby improving safety.

[0045]

BEST MODE FOR CARRYING OUT THE INVENTION

<First embodiment> §1. Overall Configuration of Heating Apparatus FIG. 1 shows a schematic configuration model diagram of a film heating type heating apparatus holding a heating body 10 according to the present invention.
The heating device of this embodiment is a pressure roller drive type, and a heating element holder 16 holding the heating element 10 according to the present invention is
The fixing roller is pressed against the pressure roller 17 with a predetermined pressing force via the cylindrical heat-resistant film 15 to form a fixing nip portion N with the heating element 10.

The pressure roller 17 is driven to rotate in the direction of arrow A by driving means (not shown). The pressure roller 17
Roller 17 and heat-resistant film 1 by rotating the
5, a rotational force acts on the heat-resistant film 15 due to the frictional force with the outer surface of the heater 5, and the heat-resistant film 15 rotates around the heater holder 16 holding the heater 10 in the direction of arrow A (the direction of the heater 10). (Width direction).

When the heat-resistant film 15 is rotated by the rotation of the pressure roller 17 and the heating element 10 is heated to a predetermined temperature by energizing the heating element 10, the heat-resistant film 15 in the fixing nip portion N is heated. A recording material P carrying an unfixed toner image T, which is a material to be heated, is inserted between the recording material P and the pressure roller 17 so that heat from the heating body 10 is transferred via the heat-resistant film 15 to the recording material P. The unfixed toner image T is heat-fixed to the surface of the recording material P.
The recording material P that has passed through the fixing nip N is conveyed after being separated from the surface of the heat-resistant film 15 by a curvature.

§2. Heating Body 10 FIG. 2 is a schematic plan view of the surface of the heating body 10 based on the first embodiment, and FIG. 3 is a schematic plan view of the back surface (back surface).

The heating element 10 of the apparatus of the present embodiment has a resistance heating element pattern 13a along the longitudinal direction thereof on the surface of the ceramic substrate 12 and a power supply electrode pattern 21 connected to one end of the heating element pattern 13a. An AC conductive pattern 13c, which is connected to the heating element pattern 13a at the end opposite to the electrode pattern 21 and is folded toward the power supply electrode pattern 21, is formed. The AC conductive pattern 1
3c is connected to a power supply electrode 22 formed on the back surface of the substrate via a through-hole 26 for current supply, and the power supply electrode 21 → the heating element pattern 13a → the AC conductive pattern 13c.
→ The power supply electrode 22 forms a primary circuit. The resistance heating element pattern 13a and the AC conductive pattern 13c are covered with a surface protection layer 11a that is screen-printed with glass paste or the like, dried, and fired in order to maintain a withstand voltage against the outside.

On the other hand, the heating element 10 according to the present embodiment includes a temperature detecting element 14 on its back surface, and DC conductive patterns 24a and 24b connected to the temperature detecting element 14, and the like.
A secondary circuit (temperature detecting means) is provided, and a glass paste or the like is screen-printed on the conductive patterns 24a and 24b to prevent migration by silver ions in the conductive patterns 24a and 24b of the secondary circuit, and dried. And the fired protective layer 11b. The secondary circuit is D
Secondary electrodes 25a and 25b and through holes 25c and 25 having C conductive patterns 24a and 24b formed on the surface side, respectively.
d, and communicates with a temperature control circuit (not shown).

In this embodiment, the DC conductive patterns 24a
24b and the protective layer 11b also serve as a substrate reinforcing member,
The width of the DC conductive pattern 24a is made wider than that of the heating element 13, and the DC conductive pattern 24a and the DC conductive pattern 24b are folded from the upstream side of the heating element 13a in the width direction, that is, in the paper conveyance direction.
It is provided downstream from c. As described above, the conductive patterns 24a, 24a,
By arranging 24b wide in the substrate width direction, heat transfer is accelerated and thermal stress is reduced. Further, the protective layer 11 increases the refraction intensity in this portion.

In this embodiment, the ceramic substrate 12
Has a horizontally long and thin shape whose longitudinal direction is the width direction perpendicular to the conveying / moving direction of the recording material P on the nip side surface. For example, the length is 270 mm, the width is 7 mm, and the thickness is 0.6.
35 mm heat-resistant, electrically insulating, low heat capacity ceramic substrate such as alumina.

The resistive heating element pattern 13a is formed by applying an electric resistance material paste (resistive paste) such as silver palladium (Ag / Pb) .Ta2N into a strip having a thickness of 10 μm and a width of 1 mm along the length of the ceramic substrate surface. It is formed by applying and firing by screen printing or the like substantially in parallel.

Then, the DC conductive patterns 24a, 24b
Is formed by applying a paste of Ag or the like by screen printing and baking. For example, a DC conductive pattern 24b is formed in a narrow band shape of 30 μm in thickness and 4 mm in width along one long side of the substrate surface. In parallel with this, a DC conductive pattern 24a is formed with a thickness of 15 μm and a width of 0.7 mm.

The DC conductive patterns 24a, 24a,
When 24b is used as a substrate reinforcing member, the DC conductive patterns 24a and 24b are formed to have strength, elasticity, ductility,
It may be made of a material having any of plasticity, good thermal conductivity, good heat insulation or a combination thereof, a width of 0.1 mm or more within the width of the substrate, and 1.
It is preferable to form it with a length of 0 mm or more and a thickness of 1.0 μm or more. More preferably, the substrate reinforcing member is formed to have a width of 1.0 mm or more, a length of 1.0 mm or more, and a thickness of 20 μm or more.

When the AC power is supplied between the power supply electrodes 21 and 22, the heating element pattern 13a generates heat,
At this time, the temperature of the heating element is detected by a temperature detecting means, and A is sent to a primary circuit by a temperature control circuit based on the temperature detection information.
The heating element 10 is controlled to a predetermined fixing temperature by adjusting the C power.

FIG. 4 shows a state in which the apparatus of this embodiment operates normally.
FIG. 4 is a schematic diagram illustrating a temperature distribution of a heater substrate at a position indicated by a G line in FIGS. 2 and 3. In the graph in the figure, the horizontal axis represents the position in the width direction of the heating element, and the vertical axis represents the temperature. During normal operation, since the pressure roller 17 and the film 15 are rotating, the heat received by the heating element 10 is transferred to the downstream side. Therefore, the peak of the temperature distribution shifts to the downstream side from the center of the heating element and is located at the substrate center x0 having the highest refraction intensity.

On the other hand, FIG. 5 shows the temperature distribution at the position indicated by the G line at the moment when excessive current flows suddenly due to runaway of the power supply control system in the heater 10 of the heating device and excessive heat is generated. is there. In this case, since the amount of heat instantaneously increases faster than the heat is transferred downstream by the pressure roller 17 and the film 15, the peak of the temperature distribution has a higher temperature α than in the normal operation, and the temperature distribution peaks on the heating element center x1. Located closer to the upstream substrate edge. Therefore, the temperature difference between the temperature peak and the downstream substrate end increases, and the thermal stress increases. When the heating device is started up and the heating device goes out of control with the stop of the pressure roller 17, the temperature distribution has the same tendency.

FIG. 6 shows the temperature distribution at the position indicated by the line H in FIG. 3 at the moment when excessive current flows rapidly due to runaway of the power supply control system and excessive heat is generated. At this time, even at the H-line position, a temperature peak having a higher value β than that in the normal use still exists on the upstream side of the substrate. However, since the DC pattern 24 and the protective layer 11b facilitate heat transfer on the substrate, The temperature from the end to the center is also equalized, and the temperature peak is lower than the G-line position, so that the thermal stress is lower than at the G-line position. Further, while the DC conduction pattern 24 and the protective layer 11b increase the refraction intensity of the substrate 12, the through-hole 27 is provided near the G-line position. Get higher. Therefore, when excessive heat is suddenly generated, it can be surely divided at the G-line position, and disconnection of the secondary circuit can be prevented.

The DC conductive pattern 24 and the protective layer 11b
Is sufficiently smaller than the heat capacity of the entire heating device, and in a steady state such as during normal use, the temperature distribution of the cross section H is as shown in FIG. Therefore, the fixability of the G-line position and the H-line position and the thermal stress do not change.

As described above, according to the present embodiment, it is intended that the fixing property does not become uneven in the longitudinal direction during normal use, and that when excessive heat is generated suddenly, cracking occurs when the temperature rises excessively. Since the thermal stress in the portion where the secondary circuit is formed is smaller than that in the portion where the through hole 27 is formed, and the strength of the substrate is higher, it is difficult to secure the edge surface distance between the primary circuit and the secondary circuit if broken. Prevent breakage of the heating element in the forming part,
The structure was designed so that it could be reliably split at the intended location, and this margin was increased to improve safety.

<Embodiment 2> FIG. 7 is a schematic plan view of a heating element 10 based on this embodiment. In this embodiment,
A dummy electrode 24c of silver paste is screen-printed on the side of the DC conductive pattern on the heater substrate where it is difficult to secure an edge distance between the primary circuit and the secondary circuit when the heater is damaged, and migration is performed in the same manner as in the first embodiment. This is covered with a protective layer 11b as a countermeasure, and the other configuration is substantially the same as that of the first embodiment.

In this embodiment, the DC conductive patterns 24a
24b, the dummy electrode 24c, and the protective layer 11b constitute a substrate reinforcing member. By forming and forming these members, the refraction intensity is increased, the material is hardly damaged, and the thermal conductivity is higher than that of the substrate 12. DC conductive pattern 2
Since the dummy electrodes 4a and 24b and the dummy electrodes 24c are provided over a wide range in the substrate width direction, even when the temperature is rapidly increased, the temperature between the edge and the central portion of the substrate can be quickly equalized, and thermal stress can be reduced. The occurrence of is suppressed.

In this embodiment, the dummy electrode 24c as one element of the substrate reinforcing member is connected to the DC conductive pattern 24a.
It is made of the same material as 24b, and does not require another kind of material. Further, since the dummy electrodes 24c are not connected, they can be provided relatively freely within a required range. Further, since the dummy electrodes 24c can be formed simultaneously with the DC conductive patterns 24a and 24b, the number of manufacturing steps is not increased, and manufacturing is easy. It is.

As described above, according to this embodiment, there is no unevenness in the longitudinal direction of the fixing property during normal use. To prevent body damage and to break at the intended location,
The safety was improved by increasing this margin.

In the above-described embodiment, the portion intended to be broken at the time of excessive temperature rise has a configuration in which a through hole is provided. However, the present invention is not limited to this. A fragile portion may be formed at a required position.
In addition, a member (holder 1) for holding a substrate, not only a fragile portion.
6) is provided with a projection or the like, and the substrate is deformed by thermal expansion (for example, if the substrate is formed with the center of the heating element and the center of the substrate displaced like the heating element 10, the difference in the amount of thermal expansion between both ends in the substrate width direction) The substrate may be configured to hold the heating element such that the substrate abuts on the projections or the like when the substrate is bent, thereby breaking the substrate at the abutting position of the projections or the like when the temperature rises excessively. <Example of Image Forming Apparatus> FIG. 8 is a schematic configuration diagram of an example of the image forming apparatus. The image forming apparatus of this embodiment is a copying machine or a printer using a transfer type electrophotographic process.

Reference numeral 41 denotes a rotating drum type electrophotographic photosensitive member, which is rotated at a predetermined process speed (peripheral speed) in a clockwise direction indicated by an arrow.

Reference numeral 42 denotes a contact charging roller as a photosensitive member charging means. A predetermined charging bias is applied to the contact charging roller 42. The surface of the rotating photosensitive member 41 is uniformly charged to a predetermined polarity and potential by the charging roller 42. You.

Exposure L of the target image information is performed on the charged processing surface of the rotating photoreceptor 41 by an image information exposure unit (not shown) such as a slit image exposure unit of a document image and a laser beam scanning exposure unit. Thus, an electrostatic latent image corresponding to the target image information is formed on the surface of the rotating photoconductor 41.

Then, a developing agent (toner) is applied to the latent image forming surface by the developing device 43 to visualize the latent image (toner image).

The toner image is transferred between the rotating photoreceptor 41 and the transfer roller 44 disposed opposite thereto (transfer section) as a recording material conveyed at a predetermined timing from a paper supply section (not shown). Is transferred to the transfer material P.

The transfer material P that has received the transfer of the toner image after passing through the transfer section is separated from the surface of the rotating photoreceptor 41, is conveyed to the image heating device R, which is the above-described film heating type heating device, and is undecided. The toner image is subjected to a heat fixing process, and is output as a copy or a print.

On the other hand, the surface of the rotary photoreceptor 41 after the transfer of the toner image to the transfer material P is cleaned by the cleaning device 45 to remove residual deposits such as untransferred toner, and is repeatedly provided for image formation.

[0074]

As described above, according to the present invention,
It is possible to provide a heating element, a heating device, and an image forming apparatus having a configuration in which a heating element substrate can be reliably split at a position intended at an excessive temperature rise.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a heating device according to a first embodiment of the present invention.

FIG. 2 is a plan model view of the surface of a heating body according to the first embodiment.

FIG. 3 is a schematic plan view of the back surface of the heating body according to the first embodiment.

FIG. 4 is a temperature distribution diagram at a position of a heating element G line during normal driving.

FIG. 5 is a temperature distribution diagram at a position of a heating body G line at the time of excessive temperature rise.

FIG. 6 is a temperature distribution diagram at a position of a heating body H line at the time of excessive temperature rise.

FIG. 7 is a plan view of a heating element according to the second embodiment.

FIG. 8 is a schematic configuration diagram of an image forming apparatus of the present invention.

FIG. 9 is a schematic configuration diagram of a conventional heating device.

[Explanation of symbols]

 Reference Signs List 10 heating element 11a, 11b protective layer 12 heating element substrate 13a, 13b resistance heating element 13c folded conductive pattern of resistance heating element 14 temperature sensing element 15 heat resistant film 16 heating element holder 17 pressure roller 21, 22 power supply electrode pattern 24a, 24b DC conductive pattern 25a, 25b Secondary electrode 25c, 25d, 26 Through-hole for conduction 27 Through-hole

Claims (21)

[Claims] 1. A heater having a heating element on a substrate, wherein the heater has a portion intended to break the substrate when the temperature is excessively increased, and a substrate reinforcing member is provided at an arbitrary portion other than the portion. Heating body. 2. A heating element in which a heating element is arranged on one side of a substrate so that a heat generation center is shifted in a width direction with respect to a substrate width center in the substrate. And a substrate reinforcing member at an arbitrary location other than the above location. 3. The heating element according to claim 1, wherein a heating element is disposed on one side of the substrate, and a temperature detecting member is disposed on the other side. 4. A temperature sensor according to claim 1, wherein a portion intended to crack the substrate when the temperature is excessively elevated and a temperature detecting member are arranged at different positions, and a substrate reinforcing member is provided on the temperature detecting member side of the portion. Item 4. A heating element according to Item 3. 5. The heating element according to claim 3, wherein the electrode of the temperature detecting member is the substrate reinforcing member. 6. A heating element or a conductive path connected to the heating element is folded back in the longitudinal direction of the substrate, an electrode of the heating element is provided at one end of the substrate in the longitudinal direction, and the substrate is broken at the time of the excessive temperature rise. The heating element according to any one of claims 1 to 5, wherein the portion is provided on the electrode side from the longitudinal center of the substrate. 7. The heating element according to claim 6, wherein an electrode of the temperature detecting member is disposed at an end of the substrate opposite to the electrode of the heating element. 8. The temperature detecting member has a conductive pattern formed on the substrate and a temperature detecting element connected to the conductive pattern, and the conductive pattern also serves as the substrate reinforcing member. The heating element according to claim 1, wherein: 9. The heating element according to claim 1, wherein the substrate is made of ceramic. 10. The heating element according to claim 1, wherein a portion intended to crack the substrate when the temperature is excessively raised is a through hole provided in the substrate. 11. The substrate reinforcing member has strength equal to or higher than that of a substrate.
The heating element according to any one of claims 1 to 10, wherein the heating element has any one of elasticity, ductility, plasticity, good thermal conductivity, and good thermal insulation or a combination thereof. 12. The heating element according to claim 1, wherein the substrate reinforcing member is formed to have a width wider than a heating element in a substrate width direction. 13. The heating element according to claim 1, wherein the substrate reinforcing member is formed to have an arbitrary width from 0.1 mm or more within the width of the substrate. 14. The heating element according to claim 1, wherein the substrate reinforcing member is formed to have an arbitrary length from 1.0 mm or more in a longitudinal direction of the ceramic substrate. . 15. The heating element according to claim 1, wherein the substrate reinforcing member is formed to have an arbitrary thickness from 1.0 μm or more. 16. The ceramic substrate as claimed in claim 1, wherein the substrate reinforcing member has a plurality of portions on the back surface of the ceramic substrate by using a plurality of kinds of members having different physical properties. Or a heating element according to claim 1. 17. A heating device comprising the heating element according to claim 1 as a heating element for heating a material to be heated. 18. A heating apparatus for bringing a material to be heated into close contact with a heating body via a heat-resistant film and applying heat of the heating body to the material to be heated via the heat-resistant film. A heating device comprising the heating element according to any one of Claims 16 to 16. 19. A heating nip portion is formed by sandwiching a heat-resistant film between a heating element and a pressure roller, and a material to be heated is introduced between the heat-resistant film and the pressure roller in the heating nip portion. It is a heating device for heat-treating the material to be heated by sandwiching and transporting the heating nip portion together with the heat-resistant film, wherein the heating element is the heating element according to any one of claims 1 to 16. Heating equipment. 20. The heating apparatus according to claim 17, wherein the material to be heated is a recording medium carrying an unfixed image, and the apparatus is a device for thermally fixing the unfixed image to the recording medium. apparatus. 21. An image forming means for forming a developer image on a recording medium, and an image heating means for heat-treating the developer image, wherein the image heating means is one of the above-mentioned claims 17 to 20. 1
An image forming apparatus, wherein the image forming apparatus is the heating apparatus described in the above section.