JP2007304315A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which is a fixing device using an electromagnetic induction heating system and in which temperature rising of a coil section and a core section is suppressed uniformly in the entire area in a transverse direction without degradation in the function of the coil section and the core section, and an image forming apparatus. <P>SOLUTION: The fixing device is equipped with a fixing member 22 which is heated by electromagnetic induction, the coil section which faces the peripheral section of the fixing member 22, the core section which faces the coil section, a cover member 29 which is disposed to cover a part or the whole of the core section, and ventilation means 40 to 42 which feed gas into the cover member 29 via a plurality of air supply openings 29a disposed in a plurality in the transverse direction of the cover member 29 and deliver the gas to the outside of the cover member 29 via a singularity or the plurality of exhaust ports 29b. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine thereof, and a fixing device installed therein, and more particularly to a fixing device and an image forming apparatus using an electromagnetic induction heating method. It is.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, an electromagnetic induction heating type fixing device has been widely used for the purpose of reducing the rise time of the device and saving energy (see, for example, Patent Document 1). .)

  In Patent Document 1 and the like, an electromagnetic induction heating type fixing device mainly includes a fixing belt as a fixing member stretched by a support roller (heating roller) and a fixing auxiliary roller (fixing roller), and a fixing belt on the support roller. An induction heating unit (excitation means) that opposes via a fixing roller, a pressure roller that faces a fixing auxiliary roller via a fixing belt, and the like. The induction heating unit includes a coil part (excitation coil) extending in the width direction (a direction orthogonal to the conveyance direction of the recording medium), a core part (core material) facing the coil part, and the like. .

The fixing belt is heated at a position facing the induction heating unit. The heated fixing belt heats and fixes the toner image on the recording medium conveyed to the positions of the auxiliary fixing roller and the pressure roller. Specifically, when a high-frequency alternating current is passed through the coil portion, magnetic lines of force are formed at the positions of the fixing belt and the support roller facing the coil portion, and an eddy current is generated on the surface of the support roller. When an eddy current is generated in the support roller, Joule heat is generated by the electrical resistance of the support roller itself. The fixing belt wound around the support roller is heated by the Joule heat.
A fixing device using such an electromagnetic induction heating method is known to be capable of increasing the surface temperature (fixing temperature) of a fixing belt to a desired temperature and using a small amount of energy and a short start-up time. It has been.

  On the other hand, Patent Document 2 discloses an electromagnetic induction heating type fixing device in which a coil portion (magnetic field generating means) is arranged on the outer peripheral side of the fixing roller, and the heating efficiency of the device is reduced by the temperature rise of the coil portion. For the purpose of suppressing such troubles, a technique of providing a ventilation path at the center of the coil portion is disclosed.

  Further, Patent Document 3 discloses an electromagnetic induction heating type fixing device in which a coil portion (induction coil) is disposed on the outer peripheral side of the fixing roller, and the heating efficiency of the device decreases due to the temperature rise of the coil portion. For the purpose of suppressing defects and the like, a technique for uniformly forming a large number of holes on the entire surface of a core portion (shield member) facing the coil portion is disclosed.

JP 2002-82549 A JP 2001-66922 A JP 2001-313162 A

  In the conventional fixing device described above, in addition to the trouble due to the temperature rise of the coil part, the trouble due to the temperature rise of the core part may occur.

Details are as follows.
When electric power is supplied to the coil part of the induction heating part in order to heat the fixing member, the coil part generates heat due to the electric resistance of the coil part itself and reaches a high temperature. Further, since the temperature around the coil portion is also raised by the fixing member heated by the electromagnetic induction of the induction heating portion, the temperature of the coil portion is further increased.

When the temperature of the coil portion is increased, the electric resistance of the coil portion is increased, so that the power efficiency is lowered and the heating efficiency of the fixing member is lowered. That is, the electric power required to raise the temperature of the fixing member to a predetermined temperature is increased.
Further, when the temperature of the coil part is increased, the insulating coating material covering the coil part may be damaged. In such a case, the insulation of the coil part is impaired and the life of the induction heating part is reduced.

On the other hand, the temperature of the core portion facing the coil portion is also raised by the coil portion that generates heat and the fixing member to be heated, so that the temperature of the core portion also increases.
When the temperature of the core part is increased, the magnetism of the core part as a ferromagnetic material is reduced. In particular, if the core part is heated and exceeds the Curie temperature, the ferromagnetism of the core part is almost lost. When the magnetism of the core portion is lowered, the magnetic flux confined in the core portion and directed toward the fixing member leaks to the outside of the core portion and does not go to the fixing member. In such a case, the heating efficiency of the fixing member is lowered.

On the other hand, the technique disclosed in Patent Document 1 aims to reduce the temperature rise of the coil part by providing a ventilation path in the center part of the coil part.
However, with this technique, there is a high possibility that the temperature rise cannot be uniformly suppressed over the entire width direction of the coil portion. That is, although the temperature rise of the coil portion is greatly reduced at the center portion in the width direction where the air passage is provided, the temperature rise of the coil portion cannot be greatly reduced at both ends in the width direction far from the air passage. Temperature unevenness occurs in the width direction. As a result, temperature unevenness in the width direction also occurs in the core portion, and further temperature unevenness in the width direction occurs in the fixing member, resulting in fixing unevenness on the output image. Such a problem occurs in the same manner even when an air passage is provided from one end side to the other end side of the coil portion to cool the coil portion. That is, although the temperature rise is greatly reduced at one end side of the coil portion, the temperature rise cannot be greatly reduced at the other end side of the coil portion. Such a problem is a problem that cannot be particularly ignored in a large-sized image forming apparatus (a device having a long length in the width direction) in which the maximum sheet passing width is set large.
Moreover, since the technique of patent document 1 etc. provide the ventilation path in the center part of a coil part, the magnetic flux formed toward a fixing member from a coil part may become weak in a center part. That is, by providing the air passage, the original function of the coil portion may be impaired.

Moreover, the technique of patent document 2 etc. aims at reducing the temperature rise of a coil part and a core part by forming many holes uniformly in the whole surface of the core part which opposes a coil part.
However, in this technique, since a large number of holes are provided in the core portion, there is a possibility that the magnetic flux leaks to the outside of the core portion and the magnetic flux directed to the fixing member is reduced to reduce the heating efficiency.

  The present invention has been made in order to solve the above-described problems, and is a fixing device using an electromagnetic induction heating method, without reducing the functions of the coil unit and the core unit. It is an object of the present invention to provide a fixing device and an image forming apparatus in which the temperature rise is suppressed uniformly over the entire width direction.

  According to a first aspect of the present invention, a fixing device is heated by electromagnetic induction, and a fixing member that heats and fixes a toner image on a recording medium to the recording medium, and a peripheral portion of the fixing member. Arranged so as to cover a part or all of the core part with a gap on the opposite side of the coil part facing the coil part, the core part facing the coil part, and the side of the core part opposite to the coil part The cover member and a plurality of air supply ports provided in the width direction of the cover member are used to send gas into the cover member and to send gas to the outside of the cover member through one or more exhaust ports. Venting means.

  The fixing device according to a second aspect of the present invention is the fixing device according to the first aspect, wherein the plurality of air supply ports are disposed on a facing surface facing the core portion, and the exhaust port is The cover member is disposed on at least one end surface of both end surfaces that meet the facing surface.

  According to a third aspect of the present invention, in the fixing device according to the first or second aspect of the present invention, the ventilation means includes an air supply fan for sending gas into the plurality of air supply ports. It is a thing.

  According to a fourth aspect of the present invention, in the fixing device according to the third aspect, the air supply fan supplies air to the plurality of air supply ports via a duct.

  The fixing device according to a fifth aspect of the present invention is the fixing device according to any one of the first to fourth aspects, wherein the ventilation means includes an exhaust fan that sucks gas from the exhaust port. It is.

  The fixing device according to a sixth aspect of the present invention is the fixing device according to any one of the first to fifth aspects, wherein the cover member is made of aluminum.

  A fixing device according to a seventh aspect of the present invention is the fixing device according to any one of the first to sixth aspects, wherein the fixing member is a fixing belt stretched around a plurality of roller members. One of the plurality of roller members is disposed at a position facing the coil portion facing the outer peripheral surface of the fixing belt via the fixing belt.

  The fixing device according to an eighth aspect of the present invention is the fixing device according to the seventh aspect, wherein one of the plurality of roller members is applied to the pressure roller that presses the recording medium to be conveyed. It is disposed at a position facing through the fixing belt.

  An image forming apparatus according to a ninth aspect of the present invention includes the fixing device according to any one of the first to eighth aspects.

  In the fixing device using the electromagnetic induction heating method, the present invention sends gas into the cover member through a plurality of air supply ports provided in the width direction of the cover member covering the core portion facing the coil portion. Gas is sent out of the cover member through the exhaust port. Accordingly, it is possible to provide a fixing device and an image forming apparatus in which the temperature rise of the coil portion and the core portion is uniformly suppressed over the entire width direction without deteriorating the functions of the coil portion and the core portion.

Embodiment.
Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
In FIG. 1, 1 is a main body of a laser printer as an image forming apparatus, 3 is an exposure unit that irradiates a photosensitive drum 18 with exposure light L based on image information, and 4 is detachably installed on the apparatus main body 1. A process cartridge as an image forming unit; 7, a transfer unit for transferring a toner image formed on the photosensitive drum 18 to a recording medium P; 10, a paper discharge tray on which an output image is placed; A paper feeding unit in which a recording medium P such as paper is stored, 13 is a registration roller that conveys the recording medium P to the transfer unit 7, 15 is a manual paper feeding unit, and 19 is an unfixed image (toner image) on the recording medium P. 1 shows a fixing device for fixing

With reference to FIG. 1, an operation during normal image formation in the image forming apparatus will be described.
First, exposure light L such as laser light based on image information is emitted from the exposure unit 3 toward the photosensitive drum 18 of the process cartridge 4. The photosensitive drum 18 rotates counterclockwise in the drawing, and a toner image corresponding to image information is formed on the photosensitive drum 18 through a predetermined electrophotographic process (charging process, exposure process, development process). Is done. Thereafter, the toner image formed on the photosensitive drum 18 is transferred onto the recording medium P conveyed by the registration roller 13 in the transfer unit 7.
Although not shown, the process cartridge 4 contains a photosensitive drum 18, a charging unit that charges the photosensitive drum 18, and toner (developer), and is formed on the photosensitive drum 18. A developing unit that develops the electrostatic latent image, a cleaning unit that removes untransferred toner remaining on the photosensitive drum 18, and the like are integrally provided.

On the other hand, the recording medium P conveyed to the transfer unit 7 operates as follows.
First, one of the plurality of paper feeding units 11, 12, and 15 of the image forming apparatus main body 1 is automatically or manually selected (for example, the uppermost paper feeding unit 11 is selected). To do.)

  Then, the uppermost sheet of the recording medium P stored in the paper feeding unit 11 is transported toward the position of the transport path K. Thereafter, the recording medium P passes through the conveyance path K and reaches the position of the registration roller 13. Then, the recording medium P that has reached the position of the registration roller 13 is conveyed toward the transfer unit 7 at the same timing in order to align with the toner image formed on the photosensitive drum 18.

Then, the recording medium P after the transfer process passes through the position of the transfer unit 7 and then reaches the fixing device 19 through the conveyance path. The recording medium P that has reached the fixing device 19 is fed between the fixing belt and the pressure roller, and the toner image is fixed by the heat received from the fixing belt and the pressure received from the pressure roller. The recording medium P on which the toner image has been fixed is sent from between the fixing belt and the pressure roller, and then is discharged from the image forming apparatus main body 1 as an output image and placed on the paper discharge tray 10.
Thus, a series of image forming processes is completed.

Next, the configuration and operation of the fixing device 19 installed in the image forming apparatus main body 1 will be described in detail with reference to FIG.
As shown in FIG. 2, the fixing device 19 includes an induction heating unit 24, a fixing auxiliary roller 21 (roller member), a fixing belt 22 (heating element), a support roller 23 (roller member), a pressure roller 30, a thermistor 37, Etc.
Here, the fixing auxiliary roller 21 is formed by forming an elastic layer such as silicone rubber on the surface of a cored bar made of stainless steel or the like. The elastic layer of the auxiliary fixing roller 21 is formed to have a thickness of 1 to 5 mm and an Asker hardness of 30 to 60 degrees.

The support roller 23 (roller member) as a heating element is a cylindrical member made of a nonmagnetic metal material, and rotates counterclockwise in FIG. An inner core 28 made of a ferromagnetic material such as ferrite is installed inside the support roller 23. The inner core 28 faces the coil portion 25 with the fixing belt 22 interposed therebetween. Here, a magnetic flux shielding member made of copper or the like can be installed at both ends of the inner core 28.
The support roller 23 may be formed of a magnetic metal material such as iron, cobalt, nickel, or an alloy thereof so that the inner core is not installed inside the support roller 23.

The fixing belt 22 (fixing member) as a heat generating member is stretched and supported by a plurality of roller members (a support roller 23 and a fixing auxiliary roller 21).
The fixing belt 22 is a multi-layered endless belt including a base layer made of polyimide or the like, a heat generating layer made of a metal such as nickel or silver, an elastic layer made of silicone rubber, or a release layer made of a fluorine compound. The releasability for the toner T is secured by the release layer of the fixing belt 22.
As the heat generating layer of the fixing belt 22, a multi-layer structure including a resin layer such as a fluorine resin, a polyimide resin, a polyamide resin, a polyamideimide resin, a PEEK resin, a PES resin, or a PPS resin and a metal layer such as nickel is used. You can also.

  The pressure roller 30 is formed by forming an elastic layer such as fluoro rubber or silicone rubber on a cylindrical member made of aluminum, copper or the like. The elastic layer of the pressure roller 30 has a thickness of 0.5 to 2 mm and an Asker hardness of 60 to 90 degrees. The pressure roller 30 is in pressure contact with the auxiliary fixing roller 21 via the fixing belt 22. Then, the recording medium P is conveyed to a contact portion (a fixing nip portion) between the fixing belt 22 and the pressure roller 30.

  The induction heating unit 24 includes a coil unit 25 (excitation coil), a core unit 26 (excitation coil core), a coil guide 27, and the like. The coil unit 25 is formed by winding a litz wire bundled with thin wires on a coil guide 27 disposed so as to cover the outer periphery of the fixing belt 22 wound around the support roller 23, and in the width direction (vertical in FIG. Direction). The coil guide 27 is a semi-cylindrical member made of an insulating material such as a resin material having high heat resistance and glass, and holds the coil portion 25. The core portion 26 is a semi-cylindrical member made of a ferromagnetic material such as ferrite (having a relative permeability of about 1000 to 3000), and a center core for forming an efficient magnetic flux toward the heating element. 26a and a side core 26b are provided. The core part 26 is installed so as to face the coil part 25 extending in the width direction.

Here, the induction heating unit 24 is covered with a cover member 29. Specifically, a cover member 29 is disposed so as to cover the core portion 26 with a gap on the opposite side of the core portion 26 from the side facing the coil portion 25.
The cover member 29 is provided with ventilation means 40 to 42 for uniformly suppressing the temperature rise of the coil portion 25 and the core portion 26 over the entire width direction. This will be described in detail later with reference to FIGS.

A thermistor 37 is in contact with the inner peripheral surface of the fixing belt 22. The thermistor 37 is a temperature sensitive element with high thermal responsiveness, and detects the temperature of the inner peripheral surface of the fixing belt 22. And based on the detection result by the thermistor 37, the heating amount by the induction heating part 24 is adjusted.
Although not shown, a thermostat is in contact with the outer peripheral surface of the support roller 23. Then, when the surface temperature on the support roller 23 exceeds a predetermined temperature, the thermostat 37 cuts off the power supply to the induction heating unit 24. Thereby, overheating of the support roller 23 by the induction heating unit 24 is limited.

The fixing device 19 configured as described above operates as follows.
By the rotation driving of the auxiliary fixing roller 21, the fixing belt 22 rotates in the direction of the arrow in FIG. 2, the support roller 23 also rotates counterclockwise, and the pressure roller 30 also rotates in the direction of the arrow. The fixing belt 22 is heated by the magnetic flux generated from the induction heating unit 24 at a position facing the induction heating unit 24.

Specifically, by supplying a high-frequency alternating current of 10 kHz to 1 MHz (preferably 20 kHz to 800 kHz) from the power supply unit (not shown) to the coil unit 25, the vicinity of the coil unit 25 (the core unit 26 and the inner core 28 are connected to each other). The magnetic field lines are alternately switched in both directions. By forming an alternating magnetic field in this manner, an eddy current is generated on the surface of the support roller 23 and the heat generating layer of the fixing belt 22, and Joule heat is generated by the electric resistance of the support roller 23 and the heat generating layer, and the support roller 23 and the heat generating layer are heated. Thus, the fixing belt 22 is heated by the heat received from the heat-generating support roller 23 and the heat generated by its own heat generation layer.
Thus, in the present embodiment, the support roller 23 functions as a heating element that is directly heated by the induction heating unit 24 and also functions as a heating member that heats the fixing belt 22. In addition, the fixing belt 22 functions as a fixing member that melts the toner image, and also functions as a heating element that is directly heated by the induction heating unit 24.

Thereafter, the surface of the fixing belt 22 heated by the induction heating unit 24 reaches a contact portion with the pressure roller 30. Then, the toner image T (toner) on the conveyed recording medium P is heated and melted.
Specifically, the recording medium P carrying the toner image T through the image forming process described above is sent between the fixing belt 22 and the pressure roller 30 (a fixing nip portion) while being guided by the guide plate. (The movement in the transport direction of the arrow Y1). The toner image T is fixed to the recording medium P by the heat received from the fixing belt 22 and the pressure received from the pressure roller 30, and the recording medium P is sent from between the fixing belt 22 and the pressure roller 30.

The surface of the fixing belt 22 that has passed the fixing position then reaches the position facing the induction heating unit 24 again.
Such a series of operations is continuously repeated to complete the fixing step in the image forming process.

Hereinafter, the ventilation means 40 to 42 of the fixing device 19, which are characteristic in the present embodiment, will be described in detail with reference to FIGS. 3 and 4.
FIG. 3 is a schematic view showing a main part of the fixing device. FIG. 4 is a schematic view of the ventilation means installed in the fixing device as viewed in the width direction.

3 and 4, the cover member 29 that covers the core portion 26 is provided with three air supply ports 29a in the width direction, and an exhaust port on one end surface (the right end surface in FIG. 4). 29b is provided.
Specifically, the three air supply ports 29a are respectively disposed on the facing surfaces of the cover member 29 that faces the core portion (the three portions are the center portion and both end portions). The exhaust port 29b is disposed on one end surface (the right end surface in FIG. 4) of both end surfaces that meet the facing surface of the cover member 29 in which the air supply port 29a is formed.

Then, air (gas) is sent into the cover member 29 through the three air supply ports 29a, and air (gas) is sent out of the cover member 29 through the exhaust port 29b. Specifically, an air supply fan 41 is connected to the three air supply ports 29 a via a duct 40. On the other hand, an exhaust fan 42 that sucks air from the exhaust port 29b is installed in the vicinity of the exhaust port 29b.
Then, the air supply fan 41 supplies air to the three air supply ports 29 a through the duct 40. The air sent from the three air supply ports 29a is sucked and discharged from the exhaust port 29b by the exhaust fan 42 after the core portion 26 is air-cooled.

As described above, in the present embodiment, air is fed into the cover member 29 from the air supply ports 29 a provided at the center and both ends of the cover member 29, and the exhaust port provided on one end surface of the cover member 29. Since air is sent out of the cover member 29 from 29b, the induction heating unit 24 is efficiently and uniformly cooled over the entire width direction. That is, the temperature rise of the core part 26 and the coil part 25 is reduced evenly over the entire width direction.
In the present embodiment, since the air passage and the hole are not formed in the core part 26 or the coil part 25 itself, the basic functions of the core part 26 and the coil part 25 are not impaired.

  Here, in the present embodiment, the cover member 29 is made of aluminum. Thereby, it becomes easy to radiate the heat dissipated from the induction heating unit 24 toward the outside of the cover member 29. Therefore, the temperature rise of the induction heating unit 24 can be further reduced.

  In the present embodiment, the exhaust port 29b is disposed on one end surface of both end surfaces that intersect with the opposing surface of the cover member 29 on which the air supply port 29a is formed, but the exhaust port 29b is provided on both end surfaces. It can also be arranged. Also in that case, an air passage for effectively cooling the induction heating unit 24 is formed, and an effect substantially equivalent to that of the present embodiment can be obtained.

  As described above, in the present embodiment, in the fixing device 19 using the electromagnetic induction heating method, a plurality of air supply ports 29 a provided in the width direction of the cover member 29 covering the core portion 26 facing the coil portion 25 are provided. The air is fed into the cover member 29 through the air, and the air is sent out of the cover member 29 through the exhaust port 29b. As a result, the temperature rise of the coil unit 25 and the core unit 26 can be uniformly reduced over the entire width direction without deteriorating the functions of the coil unit 25 and the core unit 26, so that problems such as uneven fixing of the output image can be reliably ensured. Can be deterred.

  In this embodiment, the fixing belt 22 having the heat generating layer and the support roller 23 are used as the heat generating elements. On the other hand, only one of the fixing belt 22 and the support roller 23 can be used as a heating element. Even in that case, the same effect as the present embodiment can be obtained.

  Further, in the present embodiment, the fixing device 19 is configured such that the pressure roller 30 contacts the fixing auxiliary roller 21 via the fixing belt 22. On the other hand, the fixing device 19 is configured such that the pressure roller 30 contacts the surface of the fixing belt 22 from the support roller 23 (or the auxiliary fixing roller 21) to the auxiliary fixing roller 21 (or the supporting roller 23). You can also. Even in that case, the same effect as the present embodiment can be obtained.

It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be modified as appropriate within the scope of the technical idea of the present invention, other than suggested in the present embodiment. is there. In addition, the number, position, shape, and the like of the constituent members are not limited to the present embodiment, and the number, position, shape, and the like suitable for implementing the present invention can be achieved.
In particular, in the present embodiment, the fixing device of the present invention is mounted on a monochrome image forming apparatus, but the fixing device of the present invention can also be mounted on a color image forming apparatus.

1 is an overall configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a fixing device installed in the image forming apparatus of FIG. 1. FIG. 3 is a schematic diagram illustrating a main part of the fixing device in FIG. 2. It is the schematic which looked at the ventilation means installed in a fixing device in the width direction.

Explanation of symbols

1 image forming apparatus body (apparatus body),
19 fixing device,
21 Fixing auxiliary roller (roller member),
22 fixing belt (fixing member), 23 support roller (roller member, heating element),
24 induction heating unit,
25 coil section, 26 core section,
26a center core, 26b side core,
27 coil guide, 28 inner core,
29 cover member,
29a air supply port, 29b exhaust port,
30 pressure roller,
40 duct, 41 air supply fan, 42 exhaust fan.

Claims (9)

A fixing member that is heated by electromagnetic induction and that heats and fixes the toner image on the recording medium to the recording medium;
A coil portion facing the peripheral portion of the fixing member;
A core portion facing the coil portion;
A cover member disposed so as to cover a part or all of the core portion with a gap on the opposite side of the core portion from the side facing the coil portion;
A ventilation means for sending gas into the cover member through a plurality of air supply ports provided in the width direction of the cover member and for sending gas out of the cover member through one or more exhaust ports;
A fixing device comprising: The plurality of air supply ports are disposed on a facing surface facing the core portion,
The fixing device according to claim 1, wherein the exhaust port is disposed on at least one end surface of both end surfaces that meet the facing surface of the cover member. The fixing device according to claim 1, wherein the ventilation unit includes an air supply fan that feeds gas into the plurality of air supply ports. The fixing device according to claim 3, wherein the air supply fan supplies air toward the plurality of air supply ports via a duct. The fixing device according to claim 1, wherein the ventilation unit includes an exhaust fan that sucks gas from the exhaust port. The fixing device according to claim 1, wherein the cover member is made of aluminum. The fixing member is a fixing belt stretched around a plurality of roller members,
The one roller member among the plurality of roller members is disposed at a position facing the coil portion facing the outer peripheral surface of the fixing belt via the fixing belt. Item 7. The fixing device according to Item 6. 8. The roller member according to claim 7, wherein one roller member among the plurality of roller members is disposed at a position facing a pressure roller that presses a conveyed recording medium via the fixing belt. Fixing device. An image forming apparatus comprising the fixing device according to claim 1.

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