JP2014178370A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively support large size paper of such a size as enlarged A3 paper in a simple manner without wasting energy and reducing productivity, in a fixing device including a plurality of halogen heaters for supporting various paper sizes.SOLUTION: A fixing belt as a fixing member has a halogen heater 82a having dense light distribution in the central part and a halogen heater 82b having dense light distribution at end parts arranged inside thereof. The fixing belt includes end part heaters 112 for heating the vicinities of the end parts in an axial direction of the fixing belt separately from these halogen heaters. The fixing device energizes the halogen heaters 82a and 82b, and the end part heaters 112 in feeding paper with a width of an enlarged A3 size (329 mm) or a 13-inch size (330 mm).

Description

  The present invention relates to a fixing device for fixing an unfixed image held on a recording medium, a copying machine including the fixing device, a printer, a facsimile, a plotter, and an image forming apparatus including at least one of them. Relates to the device.

In an image forming apparatus using an electrophotographic system, an electrostatic latent image is formed on the surface of a photosensitive drum as an image carrier based on image information, and the electrostatic latent image is developed with toner or the like as a developer. And visualized.
The developed image is transferred onto a recording paper (hereinafter also simply referred to as “paper”) by a transfer device to carry the image, and the toner image is fixed on the recording paper by applying pressure, heat or the like by a fixing device. ing.
As a fixing device, a heat roller method in which a nip portion is formed between rollers arranged opposite to each other, a belt fixing method in which a nip portion is formed between a roller and a belt, and the like are known.
An unfixed toner image is fixed on the recording paper by applying heat and pressure while the recording paper is nipped at the nip and conveyed.

A conventional belt fixing type fixing device will be described with reference to FIG.
A fixing belt 206 is wound around a heating roller 202 having a heater 200 inside and a fixing roller 204 having a rubber layer on the surface layer.
A pressure roller 208 is in contact with the fixing roller 204 via the fixing belt 206, and a nip portion N is formed.
In FIG. 7, reference numeral 210 denotes a tension roller, 212 denotes a spring member for urging the tension roller 210, 214 denotes a separation claw for separating the fixed recording paper S from the fixing belt 206, and 216 denotes a fixing cover. Yes.

Reference numeral 218 denotes a thermistor that detects the temperature of the fixing belt 206 at the heating roller 202.
The fixing temperature is controlled based on the detection information of the thermistor 218.
The recording paper S to which the toner image that has reached the fixing device has been transferred enters the nip portion N between the fixing belt 206 and the pressure roller 208 and is transferred in the process of passing the recording paper S through the nip portion N. The toner image is fixed by heating and pressing.
As the heater 200, a halogen heater is generally used.

In the demand for paper handling capability, there is a growing need for passing papers of various thicknesses and sizes, especially for small size papers with a paper width of around 100 mm, such as postcards and envelopes.
If the conventional fixing device is not equipped with a heating source having a heating width corresponding to the small size paper, the temperature rise in the non-sheet passing portion is large during continuous passage of the small size paper, and the productivity is lowered. I had to deal with it.
If there is a temperature gradient between the central portion and the end portion (non-sheet passing portion) in the sheet width direction, problems such as uneven glossiness occur when the next large size sheet is passed.
In order to solve this problem, for example, it is necessary to allow the fixing belt 206 and the pressure roller 208 to rotate idle in a state where the paper is not passed to make the temperature uniform, during which time productivity is lowered.

When responding without reducing productivity, the induction heating method is generally used, and a magnetic material having a magnetic shunt function at a Curie point of about 150 ° C. to 250 ° C. is used inside the belt member.
However, since the induction heating method has a higher manufacturing cost than the heating method using a halogen heater, a countermeasure for reducing the temperature rise of the non-sheet passing portion by an inexpensive method is required.
Patent Document 1 discloses a technique for improving heating efficiency by using a graphite sheet (a heating element) to provide non-uniform radiation intensity in the circumferential direction.
However, it cannot be an effective measure against the temperature rise in the non-sheet passing portion.
Further, similarly to the induction heating method, the heating source using the graphite sheet is higher in manufacturing cost than the halogen heater.

Since a heating method using a halogen heater can reduce the manufacturing cost, a method of providing a halogen heater corresponding to a small size paper and a halogen heater corresponding to a large size paper is widely adopted as a fixing method.
In the case of small size paper, the halogen heater with a dense light distribution in the center is turned on. Lights with on / off distribution to support various sizes of paper.
Here, referring to the paper size and the frequency of use, most of the normally used paper is up to A3 size, and the A3 size paper is passed in the vertical direction.
Especially for A4 (or Lt) size, which is frequently used, in order to increase productivity, paper is often passed in the horizontal direction.
For this reason, if about 300 mm is secured as the heating width of fixing, almost all cases (99% or more depending on the market model) can be covered.

On the other hand, although the frequency of use for the whole is very small, it is required to support a paper having a size larger than the width of the A3 size such as “A3 Nobi” or “13 inches”.
In the case of a heating method using a halogen heater, a plurality of heaters corresponding to small size paper (A3 size or less) are provided inside a fixing roller having a diameter of about 30 mm, so the number of heaters cannot be increased easily.
For this reason, when dealing with a large size paper such as A3 Nobi, it is necessary to lengthen the halogen heater having a dense end portion light distribution in accordance with the paper size larger than the A3 size width.
As described above, when the frequency of use is considered, heating of about 300 mm width is overwhelmingly large. However, when the halogen heater corresponding to the above large size is used with small size paper, it is heated to around 330 mm width, and the difference consumption Energy is wasted.

Furthermore, the temperature rises in the vicinity of the end of 330 mm width when the A3 size or A4 size paper is passed, and it is necessary to reduce productivity or to provide a fan in order to cool the temperature.
Further, when a reflecting plate is provided to increase the heating efficiency, there has been a problem that the temperature corresponding to the heater end portion abnormally increases.

  The present invention was devised in view of such a situation, and in a fixing device including a plurality of halogen heaters for accommodating various paper sizes, without consuming simple and wasteful energy, and The main purpose is to be able to cope with large-size paper such as A3 Nobi efficiently without reducing productivity.

  In order to achieve the above object, the present invention includes a fixing member, a fixing counter member that forms a nip portion that sandwiches and conveys a recording medium between the fixing member, and a heating source that heats the fixing member. The fixing device has an end heating source for heating the vicinity of both ends of the fixing member.

  According to the present invention, it is possible to realize a fixing device that can cope with a large size paper such as A3 Nobi efficiently without consuming unnecessary energy with a simple configuration and without reducing productivity.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic sectional view of a fixing device. FIG. 4 is a perspective view showing a support configuration of a fixing belt in the fixing device. It is a top view which shows the positional relationship of the heating area | region of the halogen heater which heats a fixing belt, and an edge part heater. FIG. 6 is a schematic configuration diagram of a fixing device according to a second embodiment. FIG. 9 is a schematic configuration diagram of a fixing device according to a third embodiment. It is a schematic block diagram of a conventional belt fixing type fixing device.

Embodiments of the present invention will be described below with reference to the drawings.
1 to 4 show a first embodiment.
First, the outline of the configuration of the image forming apparatus according to the present embodiment will be described with reference to FIG.
This image forming apparatus is a tandem type color printer in which image forming units for forming a plurality of color images are juxtaposed along the moving direction of the intermediate transfer belt.

The image forming apparatus 100 includes an image carrier that can form an image as an image corresponding to each color separated into yellow, cyan, magenta, and black.
The image carriers for the respective colors are arranged side by side as photosensitive drums 20Y, 20C, 20M, and 20Bk.

The visible toner images formed on the photosensitive drums 20Y, 20C, 20M, and 20Bk are superimposed on the intermediate transfer belt 11 as an intermediate transfer member that can move in the direction of the arrow A1 while facing the photosensitive drums. In addition, primary transfer is performed.
Thereafter, the sheet S as a recording medium is collectively transferred by the secondary transfer process.
Around each photosensitive drum 20, an apparatus for image forming processing is arranged according to the rotation of the photosensitive drum.

The photosensitive drum 20Bk that forms a black image will be described as a representative.
A charging device 30Bk, a developing device 40Bk, a primary transfer roller 12Bk, and a cleaning device 50Bk that perform image forming processing along the rotation direction of the photosensitive drum 20Bk are arranged.
An optical writing device 8 is used for writing performed after charging.

In the superimposing transfer to the intermediate transfer belt 11, the visible image formed on each photosensitive drum 20 is transferred to the same position on the intermediate transfer belt 11 while the intermediate transfer belt 11 moves in the A1 direction. To be made.
The primary transfer is performed by shifting the timing from the upstream side toward the downstream side in the A1 direction by applying a voltage from a primary transfer roller disposed opposite to each photosensitive drum with the intermediate transfer belt 11 interposed therebetween. .
The photosensitive drums 20Y, 20C, 20M, and 20Bk are arranged in this color order from the upstream side in the A1 direction.
Each of the photosensitive drums 20Y, 20C, 20M, and 20Bk is provided in an image station for forming yellow, cyan, magenta, and black images, respectively.

The image forming apparatus 100 is disposed so as to face four image stations that perform image forming processing for each color and above each photosensitive drum 20, and includes an intermediate transfer belt 11 and primary transfer rollers 12Y, 12C, 12M, And an intermediate transfer belt unit 10 having 12 Bk.
Further, the image forming apparatus 100 includes a secondary transfer roller 5 as a secondary transfer member that is disposed to face the intermediate transfer belt 11 and rotates along with the intermediate transfer belt 11.
Further, the image forming apparatus 100 includes an intermediate transfer belt cleaning device 13 that is disposed to face the intermediate transfer belt 11 and cleans the upper surface of the intermediate transfer belt 11.
In addition, the image forming apparatus 100 includes an optical writing device 8 serving as an exposure unit that is disposed below the four image stations.

The optical writing device 8 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygon mirror as a deflecting means, and the like.
The optical writing device 8 emits writing light Lb corresponding to each color to each photosensitive drum 20 to form an electrostatic latent image on each photosensitive drum 20.
In FIG. 1, for the sake of convenience, the writing light is labeled only for the black image station, but the same applies to the other image stations.

Below the image forming apparatus 100, a sheet feeding device 61 is provided as a sheet feeding cassette on which sheets S transported between the photosensitive drums 20 and the intermediate transfer belt 11 are stacked.
The sheet S conveyed from the sheet feeding device 61 is transferred between each photosensitive drum 20 and the intermediate transfer belt 11 by the registration roller pair 4 at a predetermined timing in accordance with the toner image formation timing by the image station. It is fed out toward the transfer section.
The fact that the leading edge of the paper S has reached the registration roller pair 4 is detected by a sensor (not shown).

The image forming apparatus 100 includes a film fixing type fixing device 150 for fixing the toner image on the paper S to which the toner image is transferred, and a paper discharge for discharging the fixed paper S to the outside of the main body of the image forming apparatus 100. A roller pair 7 is provided.
The upper surface of the apparatus main body is a paper discharge tray 17 on which sheets S are stacked.
Below the paper discharge tray 17, toner bottles 9Y, 9C, 9M, and 9Bk filled with toners of yellow, cyan, magenta, and black are provided.

The intermediate transfer belt unit 10 includes a driving roller 72 and a driven roller 73 around which the intermediate transfer belt 11 is wound, in addition to the intermediate transfer belt 11 and the primary transfer rollers 12Y, 12C, 12M, and 12Bk.
The driven roller 73 also has a function as a tension urging unit for the intermediate transfer belt 11. For this reason, the driven roller 73 is provided with an urging unit using a spring or the like.
The intermediate transfer belt unit 10, the primary transfer rollers 12 Y, 12 C, 12 M, and 12 Bk, the secondary transfer roller 5, and the intermediate transfer belt cleaning device 13 constitute a transfer device 71.
The sheet feeding device 61 includes a feeding roller 3 that abuts on the upper surface of the uppermost sheet S, and the uppermost sheet S is moved by rotating the feeding roller 3 counterclockwise. The sheet is fed toward the registration roller pair 4.

Although not shown in detail, the intermediate transfer belt cleaning device 13 provided in the transfer device 71 includes a cleaning brush and a cleaning blade disposed so as to face and contact the intermediate transfer belt 11. .
The intermediate transfer belt cleaning device 13 scrapes and removes foreign matters such as residual toner on the intermediate transfer belt 11 with a cleaning brush and a cleaning blade.
The intermediate transfer belt cleaning device 13 also has a discharge means (not shown) for carrying out and discarding the residual toner removed from the intermediate transfer belt 11.

Based on FIG. 2 thru | or FIG. 4, the structure of the fixing device 150 is demonstrated in detail.
FIG. 2 is a cross-sectional view in the paper width direction (axial direction), FIG. 3 is a perspective view showing a fixing belt support structure at one axial end side, and FIG. 4 is a plan view showing a heater arrangement structure.
The fixing device 150 has a fixing belt 80 as a fixing member that can be rotated in an endless (cylindrical film) having flexibility, and a halogen heater 82 as a heating source is provided in the fixing belt 80. .
The halogen heater 82 includes a halogen heater 82a having a dense light distribution at the center and a halogen heater 82b having a dense light distribution at the end.
The fixing belt 80 as a belt member is directly heated by radiant heat from the inner peripheral side by the halogen heater 82.

In addition, the fixing device 150 includes a pressure roller 84 as a fixing facing member that forms a nip portion N that presses against the fixing belt 80 and sandwiches and conveys the paper between the fixing belt 80 and a nip forming member 86. doing.
The nip forming member 86 opposes the pressure roller 84 and holds the nip forming member main body 88 disposed inside the fixing belt 80, and holds the nip forming member main body 88 against the pressure applied from the pressure roller 84. And a stay member 90.
The nip forming member main body 88 slides on the inner surface of the fixing belt 80 via a low friction sheet as a sliding sheet (not shown).
The sliding torque can be reduced by applying a lubricant such as fluorine grease or silicone oil to the sliding sheet.
The nip forming member main body 88 may be in direct contact with the inner surface of the fixing belt 80.

The fixing device 150 includes a plate-like reflection member 94 that reflects light emitted from the halogen heater 82 to the fixing belt 80.
Although not shown, the fixing device 150 includes a separating member that separates the sheet from the fixing belt 80, a pressure unit that pressurizes the pressure roller 84 to the fixing belt 80, and the like.

In FIG. 1, the shape of the nip portion N is flat, but may be a concave shape that is convex toward the fixing belt 80 as viewed from the pressure roller 84 side, or another shape.
When the nip portion has a concave shape, the discharge direction at the front end of the sheet is closer to the pressure roller, and the separation is improved, so that jamming is suppressed.
The stay member 90 prevents bending of the nip forming member main body 88 that receives pressure from the pressure roller, so that a uniform nip width can be obtained in the axial direction.

The stay member 90 has sufficient bending strength to support the nip forming member main body 88. As the material, a metal material such as stainless steel or iron, or a metal oxide such as ceramics is used.
As will be described later, the stay member 90 is positioned with both axial ends fixed to the side plate.
The fixing belt 80 is also rotatably supported by flanges described later on both sides in the axial direction.

The reflecting member 94 is fixed to the stay member 90.
The reflecting member 94 suppresses unnecessary energy consumption due to the stay member 90 being heated by radiant heat from the halogen heater 82 or the like.
The same effect can be obtained by performing heat insulation or mirror treatment on the surface of the stay member 90 instead of providing the reflecting member 94.

The pressure roller 84 has a configuration in which a silicone rubber layer is provided on a hollow metal roller. In order to obtain releasability, a release layer (PFA or PTFE layer) having a thickness of 5 to 50 μm is provided on the surface of the silicone rubber layer.
The pressure roller 84 is rotated by a driving force transmitted from a driving source such as a motor (not shown) provided in the image forming apparatus via a gear.
The pressure roller is pressed against the fixing belt by a spring or the like, and the rubber layer is crushed and deformed to form a predetermined nip width.

The pressure roller may be a solid roller, but a hollow roller may have a smaller heat capacity. The pressure roller may have a heating source such as a halogen heater.
The silicone rubber layer may be solid rubber, but if there is no heater inside the pressure roller, sponge rubber may be used.
Sponge rubber is more desirable because it increases heat insulation and makes it difficult for the fixing belt to lose heat.

The fixing belt 80 is a metal belt such as nickel or SUS having a layer thickness of 30 to 50 μm, or an endless belt using a resin material such as polyimide, or a film.
The surface layer of the belt has a release layer such as a PFA or PTFE layer, and has a release property so that toner does not adhere.
There may be an elastic layer formed of a silicone rubber layer or the like between the belt substrate and the PFA or PTFE layer.
When there is no silicone rubber layer, the heat capacity is reduced and the fixability is improved, but when the unfixed image is crushed and fixed, subtle irregularities on the belt surface are transferred to the image, causing uneven fixing on the solid portion of the image. The problem of remaining is caused.

In order to improve this, it is necessary to provide a silicone rubber layer of 100 μm or more. Due to the deformation of the silicone rubber layer, fine irregularities are absorbed and fixing unevenness is improved.
The fixing belt 80 rotates with the rotation of the pressure roller 84. The pressure roller is rotated by a driving source (not shown), and the driving force is transmitted to the fixing belt at the nip portion N, whereby the fixing belt rotates.
The fixing belt 80 is nipped at the nip portion and rotates. The fixing belt 80 is guided by holding members (flanges) held from both ends except for the nip portion, so that the cross-sectional shape of the belt stably maintains a circular shape.

As shown in FIG. 3, the fixing belt 80 is rotatably supported at both ends in the axial direction by flanges 104 as support members that protrude from the side plate 102 in the axial direction.
The flange 104 that guides both ends of the fixing belt 80 has an outer diameter that is substantially equal to the inner diameter of the fixing belt 80, and has a length that enters 5 to 10 mm from both ends of the fixing belt 80.

In other words, the flange 104 serves as a circumferential guide convex portion, and is inserted into the end portion of the fixing belt 80 and slides to maintain the cross-sectional shape of the fixing belt 80 in a circular shape.
A portion corresponding to the nip portion N of the flange 104 is opened.
Although FIG. 3 shows a support configuration on one side in the axial direction of the fixing belt 80, the other side also has the same configuration.
The stay member 90 has a length extending over the entire axial direction, and is supported by being fixed to the side plate 102 on both sides.

As shown in FIGS. 2 and 3, the flange 104 is integrally provided with a heater holding portion 110 as a holding member having a length of about 20 mm from the end of the fixing belt 80 toward the inside in the axial direction.
A concave portion 110 a is formed on the side of the heater holding portion 110 facing the inner surface of the fixing belt 80, and an end heater 112 having PTC characteristics as an end heating source is formed in the concave portion 110 a in the thickness direction of the fixing belt 80. Is slidably received in the housing.
The end heater 112 is urged toward the inner surface side of the fixing belt 80 by a plate spring 114 as urging means.

The difference between the A3 size (= A4Y) width and the A3 nobi (329 mm) and 13 inches (330 mm) is 32-33 mm.
Therefore, in the case of heating from both sides in the axial direction, if the heating can be performed by the width of the above half 16 to 16.5 mm, as shown in FIG.
Therefore, the end heater 112 may be a small heater having a length of about 20 mm.
When passing a large size sheet such as A3 Nobi or 13 inches, the halogen heaters 82a and 82b and the end heater 112 are energized.
When passing a sheet of A3 size or smaller, only the halogen heaters 82a and 82b or the halogen heater 82a are energized, and the end heater 112 is not energized.

If the halogen heater 82b is configured to be able to handle large size paper such as A3 Novi, even when the large size paper is not passed, that portion is heated and wasteful energy is consumed.
According to the configuration of the present embodiment, the above problem can be solved by adding a simple configuration in which end heaters 112 are added in the vicinity of both ends of the fixing belt 80.

Since the end heater 112 has a PTC characteristic, the resistance value increases above the set temperature and does not rise above the set temperature.
For this reason, there is no fear of combustion and belt damage, and a safe fixing device can be realized.
In this embodiment, since the end heater 112 is provided inside the fixing belt 80, the belt end can be heated from the inside without obstructing the rotation of the fixing belt 80.
If the belt contact portion of the end heater 112 is made of another smooth material, sliding resistance can be kept low, and belt running can be kept stable.
Further, since the heater holding part 110 is formed integrally with the flange 104, the end heater 112 can be disposed inside the fixing belt 80 in a space-saving manner.

Further, since the end heater 112 is pressed against the inner surface of the fixing belt 80 by the leaf spring 114, the contact area between the end heater 112 and the fixing belt 80 increases, the heat transfer effect increases, and the heating efficiency increases. Get better.
By using a spring having a small contact area or a sponge having a heat insulating effect as the urging means, it is possible to prevent the heat of the heater from being transmitted to other than the heating portion of the fixing belt 80, and this also improves the heating efficiency.
The heater holding unit 110 may be configured separately from the flange 104. This makes it difficult for the heat of the end heater 112 to be transmitted to the part other than the heater holding part 110, and the heating efficiency for the fixing belt 80 is improved.

FIG. 5 shows a second embodiment.
Note that the same parts as those in the above embodiment are denoted by the same reference numerals, and unless otherwise specified, description of the configuration and functions already described is omitted, and only the main part will be described (the same applies to other embodiments below).
In the above-described embodiment, the end heater 112 is disposed inside the fixing belt 80. However, the present embodiment is characterized in that the end heater 112 is disposed outside the fixing belt 80.

The flange 104 is integrally provided with a heater contact portion 116 that supports the inside of the fixing belt 80 facing the end heater 112.
The end heater 112 is in contact with the fixing belt 80 by pressure means (not shown).
The heater contact portion 116 is formed in an arc shape that maintains the contact of the end heater 112 with the outer surface of the fixing belt 80 and can guide the inner surface of the fixing belt 80.
In this way, if the fixing belt 80 is heated from the outer surface side by the end heater 112, the surface of the belt that melts the toner can be heated directly, which is efficient.
For users who do not need a configuration compatible with large size paper such as A3 Nobi, there is also an advantage that it is possible to easily cope with options by simply removing the outer end heater 112.

FIG. 6 shows a third embodiment.
In the present embodiment, a sleeve 118 made of a material such as polyimide is provided as an intermediate between the end heater 112 formed in a cylindrical or round bar shape and the fixing belt 80.
That is, the end heater 112 is indirectly in contact with the fixing belt 80 via the sleeve 118.
By rotating the sleeve 118 with the fixing belt 80, the belt end can be heated smoothly without causing damage due to sliding to the fixing belt 80.

In each of the above embodiments, when a heater having PTC characteristics is used, it usually takes longer to raise the temperature than a halogen heater.
For this reason, if the end heater 112 and the halogen heater 82 are heated at the same time, only the inner side of the central portion is heated first, and wasteful energy is consumed.
Further, when heat is taken away by passing paper, it takes longer to heat than the halogen heater to return to the target temperature due to the characteristics of PTC.

For this reason, it becomes possible to perform heating control with no temperature variation between the central portion and the end portion by reducing the productivity in accordance with the heating cycle of the end heater 112.
That is, when the end heater 112 that heats the vicinity of both ends of the fixing belt 80 is used, the halogen heater 82 corresponding to other normal size paper is controlled to be heated in accordance with the temperature rise at the end.
Thereby, when the calorific value of the end heater 112 that heats the end portion is low, only the heater heating section corresponding to the normal size paper is heated first, and it is possible to prevent energy from being consumed more than necessary. it can.
The transport speed when transporting a sheet of a size that uses the end heater 112 is made slower than the transport speed of a sheet of any other size.
By reducing the productivity of large-size paper that is used infrequently in this way, the heaters (end heaters 112) at both ends can be simplified (lower cost) and efficient.

  Although FIG. 4 shows a configuration having two halogen heaters, the configuration is not limited to this, and a configuration having three or more halogen heaters for handling small-size paper may be used.

S A sheet as a recording medium 80 A fixing belt as a fixing member 82a, 82b A halogen heater as a heating source 84 A pressure roller as a fixing facing member 86 A nip forming member 104 A flange as a supporting member 112 An end as an end heating source Heater 114 Leaf spring as urging means 118 Sleeve as intermediate 150 Fixing device

JP 2010-217206 A

Claims (9)

In a fixing device, comprising: a fixing member; a fixing opposing member that forms a nip portion that sandwiches and conveys a recording medium between the fixing member; and a heating source that heats the fixing member.
A fixing device having an end heating source for heating the vicinity of both ends of the fixing member. The fixing device according to claim 1,
The fixing member is a flexible endless belt member, a support member that rotatably supports both end sides of the belt member, and a nip provided inside the belt member so as to face the fixing counter member. And a forming member. The fixing device according to claim 2,
The fixing device has a configuration in which the support member is inserted into and supported by the belt member, and the end heat source is provided integrally with the support member and contacts an inner surface of the belt member. . The fixing device according to claim 3.
The end heating source is provided on the support member via a holding member, and has biasing means for biasing the end heating source or the holding member toward the inner surface of the belt member. A fixing device. The fixing device according to claim 1 or 2,
The fixing device is characterized in that the end heating source is provided outside the fixing member, and the end heating source is heated while contacting the fixing member directly or indirectly via an intermediate. In the fixing device according to any one of claims 1 to 5,
The fixing device according to claim 1, wherein the end heating source has PTC characteristics. The fixing device according to any one of claims 1 to 6,
When a recording medium having a size that uses the end heating source is conveyed, heating of the heating source is controlled in accordance with a temperature rise at the end of the fixing member. The fixing device according to claim 7,
A fixing device, wherein a conveying speed when conveying a recording medium of a size using the end heating source is made slower than a conveying speed of a recording medium of any other size.   An image forming apparatus comprising the fixing device according to claim 1.

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