JP2003131515A - Heating device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating device which can ensure high reliability by preventing the deterioration and breakage of a heater, a stay, a film, a pressure roller, etc. SOLUTION: The heating device is provided with: a heating body; the support of this heating body; a heat-resistant fixing film which is in contact with the heating body and slides over the heating body; a pressing member which drives the fixing film and brings a material to be heated in contact with the heating body through the fixing film; a first thermometer which detects the temperature of the heating body; a means to control the current to the heating body on the basis of the temperature detected with the first thermometer; a second thermometer provided in a position different from the position of the first thermometer in the longitudinal direction of the heating body and being in contact with the sliding surface of an unfixed film of the heating body; and a support of the second thermometer. The material to be heated is heated by allowing the fixing film and the material to be heated to pass together through the nip part formed by the heating body and the pressing member. The space between the support of the second thermometer and the support of the heating body at the outside of the longitudinal direction is disposed more outwardly in the longitudinal direction of the heat generating area of the heating body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device and an image forming apparatus such as a copying machine and a laser beam printer having the heating device.

[0002]

2. Description of the Related Art Conventionally, for example, in a heating device for a recording material for fixing an image by heating, a heating roller maintained at a predetermined temperature and a pressure applied to the heating roller via an elastic layer. A heat roller system is widely used in which a recording material as a heated object is nipped and conveyed by a roller and heated. or,
Other than this, various methods and configurations such as a flash heating method, an open heating method, and a hot plate heating method are known and put into practical use.

By the way, recently, in place of the above-mentioned method, a heating body (heater) fixedly supported as shown in FIG.
3, a heat-resistant film (fixing film) 2 that is conveyed while being pressed against the heating body 3, and a pressurizing body that adheres a recording material P as a heated body to the heating body 3 through the film 2 ( A film having a pressure roller 4 and heating and fixing the unfixed image formed and carried on the surface of the recording material by applying the heat of the heating body 3 to the recording material P via the film 2. Heating type heating devices have been devised.

In such a film heating type heating apparatus, since a low heat capacity heating element can be used as a heating element, it is possible to reduce the number of heating elements as compared with a conventional contact heating method such as a heat roller method or a belt heating method. Power and wait time can be shortened (quick start).

[0005]

By the way, in such a film heating type heating device, when a recording material having a width smaller than the maximum size which can be passed (hereinafter referred to as small size paper) is passed, Since heat is not taken by the recording material in the paper passing portion, the temperature becomes higher than that in the paper passing portion (temperature rise in non-paper passing portion).
In particular, when a recording material such as thick paper or envelope with a width smaller than the maximum size (hereinafter referred to as small size thick paper) is fed by double feeding, a large amount of heat is taken by the recording material in the paper passing portion. Moreover, since the temperature control is performed based on the output of the temperature detecting element provided in the paper passing portion, a large amount of electric power is supplied to the heater.

On the other hand, in the non-sheet passing portion, heat is not taken by the recording material, so that the temperature becomes extremely high, and the heater, the heater stay, the fixing film, the pressure roller and the like may be damaged.

In order to prevent the temperature rise of the non-sheet-passing portion, a temperature-sensing element for detecting the temperature rise of the non-sheet-passing portion is provided in the non-sheet-passing portion in addition to the temperature-sensing element for temperature control. Accordingly, a method of controlling so as to reduce the temperature rise of the non-sheet passing portion can be considered. In a conventional film heating type heating device, a chip thermistor is used as a temperature detecting element for temperature control,
A structure in which a chip thermistor is bonded to the non-film sliding surface side of the heater substrate and a conductive pattern for the thermistor is also formed is often used.

However, since the non-sheet passing portion becomes high in temperature, it is difficult to adopt the same structure as the temperature detecting element for detecting the temperature rise of the non-sheet passing portion from the viewpoint of heat resistance of the adhesive. Therefore, as a temperature detecting element configuration for detecting the temperature rise of the non-sheet passing portion, a method of providing a member for supporting the thermistor and bringing the thermistor and the supporting member into contact with the non-film sliding surface side of the heater substrate with a predetermined pressure is considered. (Hereinafter referred to as an external contact type thermistor). With this configuration, it is not necessary to bond the thermistor to the heater substrate, so the problem of heat resistance of the adhesive can be solved.

However, when the external contact type thermistor is used, a hole for disposing the supporting member of the external contact type thermistor is required in the stay supporting the heater. At this time, if a gap is formed between the stay and the supporting member of the external contact type thermistor in the longitudinal direction of the heating element, the void portion allows heat to escape from the heater substrate to the stay or the supporting member of the external contact type thermistor. There is no heat, so the temperature rises locally. In particular, when the temperature rise in the non-sheet passing portion is large, this local high temperature becomes remarkable, which may cause damage to the heater substrate (heater cracking) due to thermal stress and deterioration / damage of the film / pressure roller. Although this void can be made small in design, it cannot be completely eliminated in consideration of dimensional tolerance.

The present invention has been made in view of the above problems, and its object is to provide a heater stay film
An object of the present invention is to provide a heating device and an image forming apparatus capable of preventing deterioration and damage of a pressure roller and ensuring high reliability.

[0011]

To achieve the above object, the present invention provides a heating body, a support for the heating body, a heat-resistant fixing film that slides in contact with the heating body, and the fixing film. And a first temperature detecting element for detecting the temperature of the heating body, based on a temperature detected by the first temperature detecting element. And an energization control means for controlling energization to the heating element,
A second temperature measuring element in contact with the sliding surface of the non-fixing film of the heating element, which is provided at a position different from the first temperature measuring element in the longitudinal direction of the heating element, and a support for the second temperature measuring element. In the heating device, which has the fixing film and the material to be heated sandwiched and conveyed in a nip portion formed by the heating body and the pressure member, the second material is heated. It is characterized in that a gap on the outer side in the longitudinal direction between the support of the element and the support of the heating element is arranged outside the heat generating region of the heating element in the longitudinal direction.

Further, according to the present invention, in an image forming apparatus having an image forming means for forming an image on a recording material and an image heating means for heating an image on the recording material, the image heating means comprises the heating device. It is characterized by having done.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 5 is a sectional view of a laser beam printer as an image forming apparatus according to the present invention. In FIG. 5, 101 is an organic photosensitive drum as an image carrier, and 102 is a charging member. A charging roller, 103 is a laser exposure device, 104 is a developing sleeve, a developing blade, a developing device including one-component magnetic toner, 105 is a cleaning blade, 106 is a transfer roller, and 107 is a fixing device.

The organic photosensitive drum 101 comprises a charging roller 10
2 is uniformly charged to a negative charge, and the organic photosensitive drum 1 is irradiated with a laser beam from the laser exposure device 103.
An electrostatic latent image is formed at 01. Next, the charged toner in the developing device 104 adheres to the electrostatic latent image on the organic photosensitive drum 101 to form a visible image, which is transferred onto paper on the transfer roller 106 and fixed by the fixing device 107. The cleaning blade 105 removes the toner remaining on the organic photosensitive drum 101.

An image is formed by the action of each unit described above.

FIG. 3 is a schematic configuration diagram of an image heating and fixing device according to the present invention. This device is disclosed in JP-A-4-44075.
No. 44083, 4-204980 to 204984.
This is a so-called tensionless type device disclosed in Japanese Patent Publication No. This tensionless type device uses an endless belt-shaped or cylindrical heat-resistant film,
At least part of the circumference of the film is always tension-free (a state in which no tension is applied), and the film is rotationally driven by the rotational driving force of the pressure member.

2 is an endless heat-resistant film,
The film 2 is fitted onto a stay 1 which is a heat resistant film guide member including a heating body (heater) 3. The inner peripheral length of the endless heat-resistant film 2 and the outer peripheral length of the stay 1 including the heating element 3 are larger than those of the film 2 by, for example, about 3 mm. Has been done.

The stay 1 is made of a highly heat resistant resin such as polyimide, polyamideimide, PEEK, PPS, liquid crystal polymer, or a composite material of these resins and ceramics, metal, glass or the like. In this embodiment mode, a liquid crystal polymer is used.

The heat resistant film 2 has a thickness of 100 μm in order to reduce the heat capacity and improve the quick start property.
m or less, preferably 50 μm or less and 20 μm or more having high heat resistance, single layer film such as PTFE, PFA, FEP or polyimide, polyamide imide, PEEK, PES, P
PTFE, PFA, FE on the outer surface of the film such as PS
A composite layer film coated with P or the like is used.
In this embodiment, the heat-resistant film 2 has a film thickness of about 4
A 0 μm polyimide film coated with PTFE on the outer peripheral surface was used.

FIG. 2 is a front view of the heating element 3 and a diagram showing a circuit for controlling energization.

The heating element 3 is an elongated heat-resistant / insulating / heat-conductive substrate 31 having a longitudinal direction perpendicular to the conveying direction a of the heat-resistant film 2 or the recording material P as a heated object. A resistance heating element 32 formed along the longitudinal direction of the substrate at the center of the substrate 31 in the lateral direction, a heat resistant overcoat layer 34 for protecting the surface of the heating element on which the resistance heating element 32 is formed, and resistance heating. It is a heating body having a low heat capacity as a whole, which is composed of the power supply electrodes 21 and 22 at both longitudinal ends of the body 32. The stay 1 is formed by exposing the surface (film sliding surface) of the heating element 3 on which the resistance heating element 32 is formed to face downward.
It is held and fixed on the lower surface side of.

A material such as alumina or aluminum nitride is used for the heating body substrate 31, and in the present embodiment, an alumina substrate having a thickness of 1 mm, a width of 7 mm and a length of 270 mm is used. The resistance heating element 32 is, for example, Ag / Pd.
It is formed by coating an electric resistance material such as (silver palladium), RuO ₂ , Ta ₂ N or the like in a linear or linear shape by screen printing or the like. In the present embodiment, Ag / Pd is thickened by screen printing. It was formed by coating with a thickness of about 10 μm and a width of 1 mm. The power supply electrodes 21 and 22 used Ag / Pd screen-printed pattern layers. Overcoat layer 3
No. 4 used a heat resistant glass layer having a thickness of about 50 μm.

FIG. 2 also shows the contact surface of the heater 3 of the stay 1. In the present embodiment, a chip thermistor is used as the first temperature measuring element 5 and is mounted on the non-film sliding surface of the heater substrate 31. Therefore, the conductive pattern for the first temperature measuring element 5 is also formed on the non-film sliding surface side of the heater substrate 31, but it is omitted in FIG. Then, the second temperature measuring element 6 and the support member 7 of the second temperature measuring element 6 are provided at the end portion in the longitudinal direction. A chip thermistor, a bead thermistor, or the like can be used as the second temperature measuring element 6, and in the present embodiment, a chip thermistor having the same specifications as the first temperature measuring element 5 is used. A and E in FIG. 2 indicate a space between the stay 1 and the support member 7 of the second temperature measuring element 6, and hereinafter, A is described as an outer space and E is described as an inner space. The first temperature measuring element 5 and the second temperature measuring element 6 are the CPU 2
It leads to 4.

In FIG. 3, only the second temperature measuring element 6 and its supporting member 7 are shown, and the first temperature measuring element 5 is omitted.

FIG. 4 is an enlarged view of the second temperature measuring element 6 and the supporting member 7 of the second temperature measuring element 6.

The supporting member 7 includes a heat resistant resin layer 7a and a heat insulating layer 7.
b, and a chip thermistor is provided as the second temperature measuring element 6 below the heat insulating layer 7b. Also, the second
An insulating layer 8 is provided to cover the temperature measuring element 6 and the heat insulating layer 7b. In this embodiment, a liquid crystal polymer is used as the heat resistant resin layer 7a, a ceramic paper is laminated as the heat insulating layer 7b, and a polyimide film is used as the insulating layer 8.

In the heat insulation layer 7b, heat is applied from the heater 3 to the stay 1.
The purpose is to prevent the temperature in the vicinity of the second temperature detecting element 6 from escaping to the inside and lowering. The insulating layer 8 is the CPU 2
4. When the heater 3 is damaged due to failure of the heater 3 due to a failure of the first temperature detecting element 5 or the like, the resistance heating element 32 (AC) and the electrode (DC) of the second temperature detecting element 6 are connected to each other. The purpose is to ensure insulation.

The supporting member 7 of the second temperature measuring element 6 having the above structure is brought into contact with the non-film sliding surface of the heater substrate 31 with a predetermined pressure by means (not shown). In the present embodiment, the first temperature detecting element 5 is provided in an area (hereinafter referred to as the minimum paper passing area) through which the recording material having the minimum width that can be supplied to and used by the fixing device according to the present embodiment passes. , The second temperature measuring element 6
Is provided within an area (hereinafter referred to as the maximum paper passing area) through which the recording material having the maximum width which can be supplied to and used by the fixing device according to the present embodiment passes, and outside the minimum paper passing area. Therefore, when a small size sheet is passed, the position where the second temperature detecting element 6 is installed becomes the non-sheet passing portion.

Reference numeral 4 denotes a pressure roller as a film outer surface contact drive means for forming a pressure contact nip portion (fixing nip portion) N by sandwiching the film 2 with the heating body 3 and driving the film 2 to rotate. . The film driving roller / pressure roller 4 comprises a cored bar 4a, an elastic layer 4b, and an outermost release layer 4c. The film 2 is sandwiched with a predetermined pressing force by bearing means / urging means (not shown). Are arranged in pressure contact with the surface of the heating element 3. The rotational force acts on the film 2 due to the frictional force between the roller 4 and the outer surface of the film 2 due to the rotational driving of the pressure roller 4. In the present embodiment, the core metal 4
Aluminum was used as a, silicone rubber was used as the elastic layer 4b, and PFA was used as the release layer 4c.

The heating element 3 is heated by the resistance heating element 32 generating heat over the entire length of the resistance heating element 32 by feeding power to the power supply electrodes 21 and 22 at both ends of the resistance heating element 32. The temperature rise is detected by the first temperature detecting element 5, the output of the first temperature detecting element 5 is A / D converted and taken into the CPU 24, and based on this information, the electric power supplied to the resistance heating element 32 by the triac 25 is supplied. The temperature of the heating element 3 is controlled by controlling the phase and the wave number. That is, when the detected temperature of the first temperature detecting element 5 is lower than the predetermined set temperature, the heating element 3
The heating element 3 is kept at a constant temperature during fixing by controlling the energization so that the temperature rises when the temperature is higher than the set temperature. In the present embodiment, the second temperature detecting element 6 is not used for the control for keeping the heating element 3 at a constant temperature.

Then, in the state where the temperature of the heating element 3 rises to a predetermined level and the rotational peripheral speed of the film 2 by the rotation of the pressure roller 4 is stabilized, the film 2 is sandwiched and the heating element 3 is pressed. Pressure contact nip portion N formed with the roller 4
The recording material P as an object to be image-fixed, which is an object to be heated, is introduced between the film 2 and the pressure roller 4 from the image forming portion (transfer portion), and is nipped and conveyed together with the film 2 in the pressure contact nip portion N. As a result, the heat of the heating element 3 is applied to the recording material P via the film 2, and the unfixed visible image (toner image) T on the recording material P is heated and fixed on the surface of the recording material P. Then, the recording material P passing through the pressure nip portion N is separated from the surface of the film 2 and conveyed.

In the present embodiment, the temperature rise of the non-sheet passing portion is monitored by the output of the second temperature measuring element 6 provided in the non-sheet passing portion,
Control is performed to mitigate the temperature rise. As a control for reducing the temperature rise in the non-sheet passing portion, when the second temperature detecting element 6 detects a temperature equal to or higher than a certain threshold value, the throughput is lowered (the paper interval time is lengthened), the fixing temperature is lowered, and the heating member is heated. Control such as stopping the energization of 3 to temporarily suspend the image formation is conceivable. In the present embodiment, when the second temperature detecting element 6 detects a temperature equal to or higher than a predetermined temperature, the paper interval time is set longer than usual to control the throughput. Further, it is also possible to provide two or more threshold temperatures and perform control so as to mitigate the temperature rise in the non-sheet passing portion that differs depending on the threshold temperatures. Furthermore, instead of monitoring the temperature of the non-sheet passing portion, it is also possible to monitor the temperature rising speed of the non-sheet passing portion and execute control to reduce the temperature rise of the non-sheet passing portion when a certain threshold is exceeded. .

When the gaps A and E between the stay 1 and the support member 7 of the second temperature measuring element 6 are in the region where the resistance heating element 32 exists, the gap from the non-film sliding surface of the heater substrate 31 is increased. Support member 7 for stay 1 or second temperature measuring element 6
There is no transfer of heat to, resulting in high temperatures locally. In particular, when small size thick paper is fed by double feeding and the temperature rise in the non-paper feeding portion is large, the temperature becomes extremely high locally, and the heater substrate 31 is damaged (heater cracks) due to thermal stress. 2. The pressure roller 4, the supporting member 7 of the second temperature measuring element 6, and the like may be deteriorated or damaged. As described above, this void can be made small, but it is impossible to completely eliminate it due to dimensional tolerance.

With respect to the inner space E, it is possible to control the temperature rise of the non-sheet passing portion by the second temperature detecting element 6, so that the possibility of deterioration and damage is small.

On the other hand, with respect to the outer space A, when the second temperature measuring element 6 serves as a paper passing portion and the outer space A serves as a non-paper passing portion, a small-sized cardboard of a non-standard size is passed. The second temperature measuring element 6 cannot detect the temperature rise in the non-sheet passing portion, and the risk of deterioration and damage arises.

Therefore, in this embodiment, the outer space A is formed.
Are arranged outside the resistance heating element 32 in the longitudinal direction. FIG. 1 shows an enlarged view of the second temperature measuring element 6 and the vicinity of the support member 7 of the second temperature measuring element 6.

As shown in FIG. 1, in the present embodiment, the air gap A from the outer side in the longitudinal direction to the outer side, the resistance heating element 32 end B, the maximum sheet passing area end C, and the second temperature measuring element 6D are arranged in this order. There is.

First, the outer space A is the end B of the resistance heating element 32.
Since it is on the outer side of the above, even when the small size thick paper of the irregular size described above is passed through, there is no local temperature rise in the outer space A portion, and the deterioration / damage can be prevented. Next, the reason that the end B of the resistance heating element 32 is outside the end C of the maximum paper passing area is to secure the fixing property of the end portion of the recording material P.
The reason why the second temperature measuring element 6D is inside the maximum sheet passing area edge C is that the second temperature measuring element 6 does not detect the temperature rise in the non-sheet passing portion of the maximum size sheet. In the present embodiment, when the detected temperature of the second temperature detecting element 6 exceeds a certain threshold value, the throughput is controlled to be reduced, so that the second temperature detecting element 6D is outside the maximum sheet passing area edge C. And the maximum size paper may reduce the throughput. Further, from the viewpoint of accurately detecting the temperature rise in the non-sheet passing portion of the recording material having a narrow width even in small size paper, it is desirable to dispose the second temperature detecting element 6 near the center.

Further, in the present embodiment, the end of the rubber portion of the pressure roller 4 is located outside the outer space A in the longitudinal direction. If the location where the temperature locally rises is outside the end of the rubber portion, heat is not transmitted to the pressure roller 4, so the temperature becomes higher and the risk of damage to the heater 3 increases. In this embodiment, the outer space A is the resistance heating element 32.
Since it is arranged outside the region where the temperature is present, the temperature rise in that part is sufficiently small, but it is more effective to prevent damage to the heater 3 etc. if it is arranged inside the end of the rubber part.

A comparison between the conventional heating device and the heating device according to the present embodiment is shown below.

FIG. 8 shows a second example of the conventional heating device.
FIG. 3 is an enlarged view of the temperature measuring element and its vicinity. In this conventional example, an external contact type thermistor similar to that of the present embodiment is used as the second temperature measuring element. The difference from the present embodiment is that the outer space A ′ is inside the resistance heating element 32 end B and the maximum paper passing area end C in the longitudinal direction, and other than that is exactly the same as the present embodiment. It has a configuration / positional relationship.

A heater cracking test was conducted using both heating devices. In the test, in an environment of a temperature of 5 ° C., small size thick paper (216 g / m ² ) of an indeterminate size is passed so that the position of H in FIG. 8 is the edge of the paper, and then the heating device returns to room temperature. It was done by repeating the cycle of cooling with a fan and passing the paper again. By repeating a cycle in which the temperature of the heater 3 is raised and cooled at once, the thermal stress is intermittently generated in the heater substrate 31, and the heater 3 is easily damaged. When the recording material of the size used in this test is passed, the position of the second temperature measuring element 6D is the sheet passing portion in both the present embodiment and the conventional example.
It is impossible to detect the temperature rise in the non-sheet passing portion, and the outer voids A and A'become the non-sheet passing portion. Here, the outer void A,
The length of A'in the longitudinal direction was about 1 mm. This is the value when the void is the widest due to dimensional tolerance, and is the most severe condition for heater cracking. The test was conducted twice using different heating devices. Table 1 shows the results of the heater cracking test.

[0044] As shown in Table 1, in the heating device of the conventional example,
Although the heater cracked in the outer space A'in both the second time, the heater cracked did not occur in the heating device according to the present embodiment, and the stay 1, the film 2, the pressure roller 4 and the like were not deteriorated or damaged. There wasn't. In the heating device of the conventional example, since the outer space A ′ is in the region where the resistance heating element 32 exists,
It is considered that the local temperature rise was remarkable and the thermal stress generated in the heater substrate 31 exceeded the breaking stress of the heater substrate 31 and led to the heater cracking. Also in the heating device according to the present embodiment, the temperature of the outside void A is slightly higher than that of its surroundings, but since it is not in the region where the resistance heating element 32 exists, the temperature rise is sufficiently low that heater cracking occurs. No thermal stress is generated.

As described above, by using the heating device and the image forming apparatus according to the present embodiment, the second
Deterioration or damage of the heater, stay, film, pressure roller, etc. due to the gap between the stay and the support member of the second temperature detecting element that may occur when an external contact type thermistor is used as the temperature measuring element of Can be prevented.

Although the present embodiment is a heating device for passing the recording material on the basis of the center, the present invention is also applicable to a heating device for passing the recording material on the basis of the end portion. Further, although one temperature detecting element for detecting the temperature rise in the non-sheet passing portion is provided in the present embodiment, a plurality of temperature detecting elements may be provided at different positions in the longitudinal direction of the heating body.

<Second Embodiment> Next, a second embodiment of the present invention will be described.

In this embodiment, the first temperature detecting element is also an external contact type thermistor. Other configurations of the heating device and the image forming apparatus are similar to those of the first embodiment.

FIG. 6 is a front view of the heating element 3 according to the present embodiment and a diagram showing a circuit for controlling energization. FIG. 6 also shows the contact surface of the heater 3 of the stay 1.

In the present embodiment, the same chip thermistor as the second temperature measuring element 6 of the first embodiment is used as the first temperature measuring element 9, and the supporting member 10 for the first temperature measuring element 9 is used.
Also has the same configuration as the support member 7 of the first embodiment. Therefore, an enlarged view of the first temperature measuring element 9 and its supporting member 10 is the same as FIG. 4 described in the first embodiment. In the present embodiment, the first temperature measuring element 9 and its supporting member 10 are arranged within the minimum sheet passing area.

When the first temperature measuring element 9 is of the external contact type,
Since it is not necessary to form the conductive pattern for the mounting type chip thermistor described in the first embodiment on the heater substrate 31, it is possible to reduce the width of the heater substrate as compared with the case where the conductive pattern is formed. When the width of the heater substrate is narrowed, the distance from the end of the heater substrate 31 to the resistance heating element 32 can be reduced in the heater width direction, and therefore the temperature distribution in the heater width direction becomes closer to uniform. Since the thermal stress decreases as the temperature distribution in the heater width direction becomes closer to uniform, the configuration of the present embodiment is more effective in preventing heater cracking than the configuration of the first embodiment. Of course, if the width of the heater substrate is narrowed, the cost can be reduced and the wait time can be shortened by lowering the heat capacity.

Further, in the case of the present embodiment, when the heater 3 is damaged due to the failure of the CPU 24, the first temperature detecting element 9, etc., the energization control to the heater 3 becomes impossible, the resistance heating element 32 is used.
Insulation between (AC) and the first temperature detecting element 9 (DC) can be reliably ensured. Therefore, as compared with the first embodiment in which the thermistor is mounted on the back surface of the heater substrate, the safety at the time of failure of the heating device and the image forming apparatus is improved.

However, in the structure of the present embodiment, since the insulating layer (polyimide film) is present between the first temperature detecting element 9 and the heater substrate 31, the responsiveness is higher than that of the first embodiment. It gets a little worse.

Support member 1 for stay 1 and first temperature measuring element 9
Regarding the voids with 0 (F, G in FIG. 6), the voids A, E
Although the temperature rises locally like the above, since they are both within the minimum sheet passing area and are not affected by the temperature rise in the non-sheet passing portion, the deterioration or damage of the heater or the like due to them does not occur.

By using the heating device and the image forming apparatus having the above structure, the second device can be used as in the first embodiment.
Prevents deterioration and damage of heaters, stays, films, pressure rollers, etc. due to the gap between the stay and the support member of the second temperature sensing element that may occur when an external contact type thermistor is used as the temperature sensing element can do. Also, CP
The safety at the time of failure of U, the first temperature detecting element, etc. is also improved.

Although the present embodiment is a heating device for passing the recording material on the basis of the center, the present invention is also applicable to a heating device for passing the recording material on the basis of the end portion. Further, although one temperature detecting element for detecting the temperature rise in the non-sheet passing portion is provided in the present embodiment, a plurality of temperature detecting elements may be provided at different positions in the longitudinal direction of the heating body.

[0057]

As is apparent from the above description, according to the present invention, there is a possibility that the stay and the second temperature sensing element may be supported when an external contact type thermistor is used as the second temperature sensing element. It is possible to prevent deterioration and damage of the heater, stay, film, pressure roller, etc. due to the gap between the members, and it is possible to improve the reliability of the heating device and the image forming apparatus.

[Brief description of drawings]

FIG. 1 is an enlarged view of a vicinity of a second temperature measuring element and its supporting member of a heating device according to a first embodiment of the present invention.

FIG. 2 is a front view of a heating body of the heating device according to the first embodiment of the present invention and a diagram showing a circuit for controlling energization.

FIG. 3 is a schematic configuration diagram of a heating device (film heating type image heating and fixing device) according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a second temperature measuring element and its supporting member of the heating device according to the first embodiment of the present invention.

FIG. 5 is a schematic sectional view of an image forming apparatus (laser beam printer) according to the present invention.

FIG. 6 is a front view of a heating body of a heating device according to a second embodiment of the present invention and a diagram showing a circuit for controlling energization.

FIG. 7 is a schematic configuration diagram of a conventional heating device (film heating type image heating and fixing device).

FIG. 8 is an enlarged view of the vicinity of a second temperature measuring element and its supporting member in an example of a conventional heating device.

[Explanation of symbols]

1 stay 2 fixing film 3 heater (heating body) 4 Pressure roller (Pressure body) 4a core metal 4b elastic layer 4c Release layer 5 First temperature measuring element 6 Second temperature measuring element 7 Second temperature measuring element support member 7a Heat resistant resin layer 7b heat insulation layer 8 insulating layers 9 First temperature measuring element 10 First temperature measuring element support member 24 CPU 25 triacs 26 AC power supply 31 substrate 32 resistance heating element 34 Overcoat layer N Nip part P recording material T toner

Claims (6)

[Claims] 1. A heating body, a support for the heating body, a heat-resistant fixing film that comes into contact with and slides on the heating body, and a heating material that drives the fixing film and heats a material to be heated through the fixing film. A pressurizing member brought into close contact with the body, a first temperature detecting element for detecting the temperature of the heating body, and an energization control means for controlling energization of the heating body based on the temperature detected by the first temperature detecting element,
A second temperature measuring element in contact with the sliding surface of the non-fixing film of the heating element, which is provided at a position different from the first temperature measuring element in the longitudinal direction of the heating element, and a support for the second temperature measuring element. A heating device that heats a material to be heated by sandwiching and transporting the fixing film and the material to be heated together with a nip portion formed by the heating body and the pressing member, wherein the second temperature measurement A heating device, characterized in that a gap on the outer side in the longitudinal direction between the support of the element and the support of the heating element is arranged outside the heat generating region of the heating element in the longitudinal direction. 2. The heating device according to claim 1, wherein the region through which the material to be heated having the maximum usable width passes is located inside the heating region of the heating body in the longitudinal direction. 3. The first temperature measuring element is provided in a region through which a usable minimum-width heated material passes, and the second temperature measuring element is provided outside a minimum-width-enabled heated material pass region. The heating device according to claim 1 or 2, wherein the heating device is provided in a region through which a material to be heated having a maximum usable width passes. 4. The second temperature measuring element and its support are
From the non-fixing film sliding surface of the heating element to the insulation layer, temperature sensor,
The heating device according to claim 1, wherein a heat insulating layer and a heat resistant resin layer are formed in this order. 5. The heating apparatus according to claim 1, wherein the control is changed according to the temperature detected by the second temperature detecting element. 6. An image forming apparatus having an image forming means for forming an image on a recording material and an image heating means for heating an image on the recording material, wherein the image heating means is any one of claims 1 to 5. An image forming apparatus comprising the above described heating device.