JP2011215488A - Fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve followability of a temperature-detecting means to the outer peripheral surface of a heating roller without doing damage to the outer peripheral surface of the heating roller in a fixing device of an image forming device.SOLUTION: The fixing device 33 used for the image forming device 1 includes the heating roller 61, a temperature-detecting member 83 and a magnet 6. The temperature-detecting member 83 is a member for detecting a temperature in contact with the heating roller 61. The magnet 6 presses the temperature-detecting member 83 against the heating roller 61 by magnetic action.

Description

  The present invention relates to a fixing device and an image forming apparatus using the same, and more particularly to a fixing device that measures a temperature by bringing a temperature detection member into contact with a heating roller and an image forming apparatus using the same.

  An electrophotographic image forming apparatus such as a copying machine, a facsimile machine, or a multifunction machine includes a charger, an exposure device, a developing device, and a transfer device around a photosensitive drum. In such an image forming apparatus, the photosensitive drum is charged and further exposed to form an electrostatic latent image on the surface of the photosensitive drum. Thereafter, the electrostatic latent image is developed to form a toner image, and the toner image is further transferred onto a predetermined sheet.

  The image forming apparatus further includes a fixing device. The fixing device is a device for fixing a toner image on a sheet, and includes a heating roller and a pressure roller. The heating roller has a heating element inside. The pressure roller is in contact with the heating roller to form a contact portion through which the paper passes. For example, a thermistor is used as a sensor for measuring the temperature of the heating roller for temperature control (for example, Patent Document 1). See).

Japanese Utility Model Publication No. 1-73865

The thermistor is urged to the heating roller by a leaf spring in order to maintain the contact state with the heating roller.
However, the thermistor may move away without following the movement of the heating roller due to, for example, rattling during rotation of the heating roller. In this case, accurate temperature measurement cannot be performed. On the other hand, if the urging force of the leaf spring is increased in order to improve the followability of the thermistor, the thermistor may be strongly pressed against the heating roller, thereby causing damage to the outer peripheral surface of the heating roller. In particular, the leaf spring may not evenly bias the thermistor when it is deformed, and in this case, the heating roller may be damaged due to uneven contact.

  An object of the present invention is to improve the followability of a temperature detection member to an outer peripheral surface of a heating roller without damaging the outer peripheral surface of the heating roller in a fixing device of an image forming apparatus.

A fixing device according to an aspect of the present invention is a fixing device used in an image forming apparatus, and includes a heating roller, a temperature detection member, and a magnetic member. The temperature detection member is a member for detecting the temperature in contact with the heating roller. The magnetic member presses the temperature detection member against the heating roller by a magnetic action.
In this apparatus, the temperature detecting member is pressed against the heating roller evenly by magnetic action. That is, since the bias of the pressing force is small, the heating roller is not easily damaged even if the pressing force is increased.

The heating roller is made of a magnetic material, and the magnetic member may have a first magnetic member that presses the temperature detection member against the heating roller by attracting the heating roller.
In this apparatus, since the heating roller has magnetism, it is not necessary to provide another magnetic member corresponding to the magnetic member.

The magnetic member has a first magnetic member and a second magnetic member arranged so as to repel each other with respect to the first magnetic member, and the temperature is generated by the repulsive force of the first magnetic member and the second magnetic member. The detection member may be pressed against the heating roller.
In this apparatus, the temperature detection member is pressed against the heating roller by utilizing the repulsive force between the magnetic members. Therefore, when the temperature detection member moves away from the heating roller, the repulsive force increases, so that the temperature detection member quickly approaches the heating roller.

The first magnetic member has a curved surface along the peripheral surface of the heating roller, and the temperature detecting member is interposed between the curved surface and the peripheral surface of the heating roller in a state where the temperature detecting member is pressed against the heating roller. It may be sandwiched.
In this apparatus, since the followability of the temperature detection member to the heating roller is improved, the temperature detection member detects the temperature more accurately.

The fixing device may further include a rotating member having a first end to which the first magnetic member is fixed and a second end that is rotatably supported.
In this apparatus, for example, when the heating roller is rattling, the temperature detecting member follows the heating roller by rotating the rotating member.

  An image forming apparatus according to another aspect of the present invention includes the above-described fixing device.

  In the fixing device and the image forming apparatus according to the present invention, the temperature detection member is uniformly pressed against the heating roller by the magnetic action in the portion where the temperature detection member and the heating roller are in contact with each other. As a result, even if the pressing force is increased, the heating roller is hardly damaged.

1 is a schematic diagram of an entire image forming apparatus including a first embodiment according to the present invention. FIG. 3 is a control configuration diagram of main parts of the image forming apparatus. The top view of a heating roller and a temperature detection member. FIG. 3 is a schematic cross-sectional view of a heating roller and a temperature detection member in the first embodiment. The schematic cross section of the temperature detection member in 1st Embodiment. The schematic cross section of the heating roller and temperature detection member in 2nd Embodiment. The schematic cross section of the temperature detection member in 2nd Embodiment. The schematic cross section of the heating roller and temperature detection member in 3rd Embodiment. The schematic cross section of the heating roller and temperature detection member in 4th Embodiment. The schematic cross section of the heating roller and temperature detection member in 5th Embodiment. The schematic cross section of the heating roller and temperature detection member in 6th Embodiment.

(1) Structure of Image Forming Apparatus The image forming apparatus will be described with reference to FIG. FIG. 1 is a schematic diagram of an entire image forming apparatus including an embodiment according to the present invention. Hereinafter, in order to clarify the directional relationship in the image forming apparatus 1, the directions for the worker standing on the front surface (front side in FIG. 1) of the image forming apparatus 1 are the left-right direction, the front-rear direction, and the vertical direction. .

The image forming apparatus 1 includes an image reading device 2 and an image forming device main body 3.
The image reading apparatus 2 includes an image reading unit 21 and a document cover 22. The image reading unit 21 is a device that reads image data of a document, and is a so-called flatbed scanner. The image reading unit 21 includes a light source 23, a plurality of reflecting mirrors 24, and a scanner unit 25. In the image reading unit 21, the light irradiated and reflected from the light source 23 onto the original on the platen glass 26 is guided to the scanner unit 25 while being reflected by the plurality of reflecting mirrors 24. The document cover 22 is rotatably disposed on the image reading unit 21.

  The image forming apparatus main body 3 includes a housing 31, and an image forming unit 32, a fixing device 33, a paper transport unit 34, a paper feed cassette 35, a manual paper feed tray 36, and a discharge unit provided inside the housing 31. A paper portion 37 is provided.

  The image forming unit 32 forms an image on the paper P based on the image data of the original read by the image reading device 2 and the image data sent from the personal computer. The image forming unit 32 includes a photosensitive drum 40, a charger 41, an exposure head 42, a developing device 43, a transfer roller 44, and a cleaning roller 45.

  The photosensitive drum 40 is a device that forms an electrostatic latent image on the surface. The photosensitive drum 40 is a columnar member that is rotatably provided. The photosensitive drum 40 is rotated counterclockwise in FIG. 1 about a rotation axis perpendicular to the paper surface direction of FIG. 1 by a driving device (not shown). The charger 41, the exposure head 42, the developing device 43, the transfer roller 44, and the cleaning roller 45 are provided in this order in the rotation direction of the photosensitive drum 40.

  The charger 41 uniformly charges the surface of the photosensitive drum 40. The charger 41 is, for example, a corona discharge type device.

  The exposure head 42 draws an electrostatic latent image along the image data by irradiating the surface of the charged photosensitive drum 40 with light. The exposure head 42 includes, for example, an LED (Light Emitting Diode) as a light source.

  The developing device 43 supplies toner to the electrostatic latent image on the photosensitive drum 40 and develops the electrostatic latent image. As shown in FIG. 2, the developing device 43 mainly includes a developing device main body 50, a developing roller 51, a supply roller 52, a first stirring member 55, and a second stirring member 56. The developing device main body 50 includes a first toner chamber 53 and a second toner chamber 54, and houses the developing roller 51, the supply roller 52, the first stirring member 55, and the second stirring member 56 therein. .

The developing roller 51 is rotatably disposed at a position in the developing device main body 50 and in contact with the photosensitive drum 40. The developing roller 51 supplies the toner received from the supply roller 52 to the photosensitive drum 40 and develops the latent image on the photosensitive drum 40 using the toner.
The supply roller 52 is disposed in the developing device main body 50 so as to be rotatable to a position in contact with the developing roller 51. The supply roller 52 supplies the toner stored in the first toner chamber 53 to the developing roller 51.

  The first toner chamber 53 and the second toner chamber 54 store toner replenished from a toner cartridge (not shown). The first stirring member 55 and the second stirring member 56 are provided in each of the first toner chamber 53 and the second toner chamber 54 and send the toner toward the supply roller 52 while stirring the toner.

The transfer roller 44 is disposed to face the photosensitive drum 40 and transfers the toner image on the photosensitive drum 40 onto the paper P.
The cleaning roller 45 removes the toner remaining on the photosensitive drum 40 after the transfer.

  The fixing device 33 is a device that fixes the toner image on the paper P by applying heat and pressure to the paper P after the transfer. The fixing device 33 includes a heating roller 61 and a pressure roller 63.

  The heating roller 61 has a cylindrical roller body 61a and a halogen lamp 61b as a heat source. The halogen lamp 61 b is energized and controlled by the heater drive circuit 76. A temperature detecting member 83 is disposed on the surface of the roller body 61a of the heating roller 61 so as to be in contact therewith.

  A motor 64 is connected to the heating roller 61. The motor 64 is a device for driving the heating roller 61. The motor may drive not the heating roller but the pressure roller, or may drive both the heating roller and the pressure roller. Further, the motor may be dedicated to the fixing device, or may drive another rotating body of the image forming unit.

  The pressure roller 63 includes a metal roller shaft and an elastic member provided around the roller shaft. The pressure roller 63 is rotatably supported by the apparatus main body and is biased by the heating roller 61 by a biasing member (not shown) to form a nip portion 65. The pressure roller 63 is driven to rotate when the heating roller 61 rotates.

  The paper transport unit 34 includes a transport path and a plurality of rollers. The paper transport unit 34 transports the paper P along the transport path using rollers, so that a paper discharge unit passes through the image forming unit 32 and the fixing device 33 from a paper feed cassette 35 or a manual paper feed tray 36 described later. Up to 37, the paper P is conveyed.

The paper feed cassette 35 accommodates a bundle of paper P before image formation. The paper feed cassette 35 is provided so as to be able to be taken in and out of the housing 31.
The manual paper feed tray 36 has a manual paper feed function for special paper such as backing paper.
The paper discharge unit 37 is a part for discharging the paper P on which an image is formed. The paper discharge unit 37 is on the upper surface of the housing 31.

(2) Control Configuration of Image Forming Apparatus The control configuration of the image forming apparatus will be described with reference to FIG. FIG. 2 is a control configuration diagram of main parts of the image forming apparatus.

  The printer control board 71 is a control unit for controlling the operation of each unit of the image forming apparatus, and includes a computer that performs control by executing the read software. The computer constituting the printer control board 71 has a CPU, RAM, and ROM.

  Connected to the printer control board 71 are a transfer high-voltage power supply 72, a development high-voltage power supply 73, a charging high-voltage power supply 74, a cleaner high-voltage power supply 75, a heater drive circuit 76, and a motor drive circuit 78.

  The transfer high-voltage power supply 72 is a device for applying a transfer voltage to the transfer roller 44 based on a command from the printer control board 71.

  The developing high-voltage power source 73 is a device for applying a developing voltage to the developing roller 51, the supply roller 52, and the blade 57 based on a command from the printer control board 71.

  The charging high-voltage power source 74 is a device for applying a charging voltage to the charger 41 based on a command from the printer control board 71.

  The cleaner high-voltage power supply 75 is a device for applying a voltage to the cleaning roller 45 based on a command from the printer control board 71.

  The heater drive circuit 76 is a device for on / off controlling the heating roller 61 based on a command from the printer control board 71. The surface temperature of the heating roller 61 is maintained at the fixing temperature as follows. The heater drive circuit 76 turns off the halogen lamp 61b when the surface temperature of the heating roller 61 becomes higher than the fixing temperature, and turns on the halogen lamp 61b when the surface temperature of the heating roller 61 becomes lower than the fixing temperature.

  The motor drive circuit 78 is a device for controlling the operation of the motor 64 based on a command from the printer control board 71.

  The printer control board 71 is further connected with a tonia end sensor 81 and a temperature detection member 83. The tonia end sensor 81 is provided at the bottom of the developing device main body 50 and transmits a tonia end sensor signal to the printer control board 71 when the toner is about to run out. The temperature detection member 83 detects the temperature of the heating roller 61 in the fixing device 33 and transmits a temperature sensor signal to the printer control board 71.

(3) First Embodiment of Fixing Device The structure of the fixing device 33, particularly the structure of the heating roller 61 and the temperature detecting member 83, will be described in detail with reference to FIGS.
FIG. 3 is a plan view of the heating roller and the temperature detection member. The roller body 61a is made of a ferromagnetic material such as ferritic stainless steel, iron, or nickel. A temperature detecting member 83 is disposed on the surface of the roller main body 61a of the heating roller 61 so as to come into contact therewith.

FIG. 4 is a schematic cross-sectional view of the heating roller and the temperature detection member. The temperature detection member 83 includes the extension member 4, the thermistor element 5, and the magnet 6.
The extension member 4 is a member that is elongated in one direction, and is made of, for example, metal. A thermistor element 5 and a magnet 6 are fixed to the distal end 4 a of the extension member 4. In this embodiment, the extending member 4 extends linearly in the tangential direction of the cylinder of the heating roller 61.
The thermistor element 5 and the magnet 6 are fixed to the tip 4 a of the extension member 4. In this embodiment, the extension member 4 is curved and is fixed to a support member 68 provided in the fixing device housing 67 by a fixing member 8 provided at the root end 4b.

  FIG. 5 is a schematic cross-sectional view of the temperature detection member.

  The thermistor element 5 is disposed on the side of the heating roller 61 that contacts the roller body 61a.

  The magnet 6 is disposed on the opposite side of the thermistor element 5 from the heating roller 61. The magnet 6 has a rectangular parallelepiped shape and has six flat surfaces. In this embodiment, the arrangement of the polarities of the magnet 6 is not limited.

An insulator 7 is disposed between the thermistor element 5 and the magnet 6. The insulator 7 is provided to adjust the strength of the magnetic field generated between the magnet 6 and the roller body 61a.
The strength of the magnetic field generated between the magnet 6 and the roller body 6a may be adjusted by adjusting the magnetic force between the magnet 6 and the roller body 6a without providing the insulator 7. In addition, the insulator 7 may be provided only in a region corresponding to the region where the thermistor element 5 is disposed to protect the thermistor element 5 from the magnetic field.

  The thermistor element 5 is coated with a nonmagnetic material such as a resin, and is thus less susceptible to the magnetic field of the magnet 6.

  Since the roller body 61 a of the heating roller 61 is a magnetic body, the thermistor element 5 of the temperature detection member 83 is urged toward the outer peripheral surface of the heating roller 61 by the magnetic action of the magnet 6 as shown in FIG. In the state shown in FIGS. 4 and 5, the extension member 4 is not elastically deformed, and therefore the elastic force from the extension member 4 hardly acts on the heating roller 61. However, as another embodiment, the elastic force of the extension member 4 may be set so as to act on the heating roller 61. In this case, however, the elastic force of the extension member 4 is preferably smaller than the force with which the magnet 6 and the roller body 61a of the heating roller 61 are attracted.

  In this apparatus, the temperature detection member 83 is evenly pressed against the heating roller 61 by a magnetic action. That is, since the bias of the pressing force is small, the heating roller 61 is not easily damaged even if the pressing force is increased.

  In this apparatus, since the heating roller 61 has magnetism, it is not necessary to provide another magnetic member corresponding to the magnet 6.

(4) Second Embodiment FIG. 6 is a schematic cross-sectional view of a heating roller and a temperature detection member in the second embodiment.

FIG. 7 is a schematic cross-sectional view of the heating roller and the temperature detection member. The temperature detection member 83 includes an extension member 4 ′, a thermistor element 5, and a magnet 6 ′. The extending member 4 ′ has a material and a shape that are highly flexible and easily deformable. The extending member 4 ′ is made of resin, for example. A thermistor element 5 and a magnet 6 'are fixed to the distal end 4a' of the extending member 4 '.
In this embodiment, the extending member 4 extends linearly in the tangential direction of the cylinder of the heating roller 61. More specifically, the extension member 4 ′ extends in the horizontal direction, and the root end 4 b ′ of the extension member 4 ′ is placed on the upper surface of the support member 68 provided in the fixing device housing 67.

  A surface 6 a ′ of the magnet 6 ′ on the thermistor element 5 side is a curved surface along the outer peripheral surface shape of the roller body 61 a of the heating roller 61. Accordingly, the thermistor element 5 is sandwiched between the magnet 6 ′ and the heating roller 61 and deformed along both surfaces in a state where the thermistor element 5 is pressed against the heating roller 61 by the magnet 6 ′. As a result, the degree of adhesion between the thermistor element 5 and the heating roller 61 is improved. In other words, the followability of the temperature detection member 83 to the heating roller 61 is improved, so that the temperature detection member 83 can detect the temperature of the heating roller 61 more accurately.

In this apparatus, since the followability of the temperature detection member 83 to the heating roller 61 is improved, the temperature detection member 83 detects the temperature more accurately.
In addition, since a flexible material other than metal is used for the extension member 4 ′, there is an advantage that no sag occurs, and an advantage that the temperature detecting member 83 is stabilized in temperature without taking heat away.

(5) Third Embodiment FIG. 8 is a schematic cross-sectional view of a heating roller and a temperature detection member in a third embodiment.
In this embodiment, the thermistor element 5 and the magnet 6 are fixed to the distal end 9 a of the rigid extension member 9. The extension member 9 extends in the tangential direction of the heating roller 61. A rotation member 10 is provided at the base end 9 b of the extension member 9. The rotating member 10 is rotatable around a shaft 11 provided in the apparatus main body. The shaft 11 extends in the same direction as the rotation shaft of the heating roller 61. Thereby, the front-end | tip 9a of the extension member 9 is movable between the position which contacts the outer peripheral surface of the roller main body 61a of the heating roller 61, and the position away from it.
In this apparatus, for example, when the heating roller 61 is rattling, the temperature detection member 83 follows the heating roller 61 as the extension member 9 rotates.

(6) Fourth Embodiment FIG. 9 is a schematic cross-sectional view of a heating roller and a temperature detection member in a fourth embodiment.

  In this embodiment, the extending member 12 extends in the tangential direction with respect to the heating roller 61. The extension member 12 extends linearly. Unlike FIG. 4, the extending member 12 extends obliquely with respect to the horizontal plane. The extension member 12 is fixed to a support member 68 ′ provided in the fixing device housing 67 by a fixing member 13 provided at the root end 12 b.

(7) Fifth Embodiment FIG. 10 is a schematic cross-sectional view of a heating roller and a temperature detection member in a fifth embodiment.
In this embodiment, unlike the first to fifth embodiments, the roller body 61a ′ of the heating roller 61 ′ is made of a nonmagnetic material such as aluminum.

  The temperature detection member 83 ′ includes the extension member 14, the thermistor element 15, the first magnet 16, and the second magnet 17. The extension member 14 is a member made of a rigid body and elongated in one direction. The thermistor element 15 and the first magnet 16 are fixed to the distal end 14 a of the extension member 14. In this embodiment, the extension member 14 extends linearly in the tangential direction of the cylinder of the roller body 61a 'of the heating roller 61'. The extension member 14 extends obliquely in this embodiment. A rotation member 85 is provided at the root end 14 b of the extension member 14. The rotating member 85 is rotatable around a shaft 86 provided in the apparatus main body. The shaft 86 extends in the same direction as the rotation shaft of the heating roller 61 '. Thereby, the front end 14a of the extension member 14 is movable between a position in contact with the outer peripheral surface of the roller main body 61a 'of the heating roller 61' and a position away from the position.

  The second magnet 17 is fixed to the support member 68 at a position facing the first magnet 16 (a position opposite to the heating roller 61 ′ of the first magnet 16). The first magnet 16 and the second magnet 17 have the same poles facing each other and repel each other. By this repulsive force, the thermistor element 15 is biased to the outer peripheral surface of the roller body 61a 'of the heating roller 61'.

  As described above, since the first magnet 16 and the second magnet 17 are disposed so as to repel each other, the temperature detection member 83 ′ is heated by the repulsive force of the first magnet 16 and the second magnet 17. It is pressed against. Therefore, when the temperature detection member 83 ′ moves away from the heating roller 61 ′, the repulsive force increases, so that the temperature detection member 83 quickly approaches the heating roller 61 ′.

(8) Sixth Embodiment FIG. 11 is a schematic cross-sectional view of a heating roller and a temperature detection member in a sixth embodiment.
In this embodiment, unlike the first to fifth embodiments, the roller body 61a ′ of the heating roller 61 ′ is made of a nonmagnetic material such as aluminum.

  In this embodiment, the thermistor element 15 and the first magnet 16 are fixed to the tip 19 a of the extension member 19. The extension member 19 extends linearly in a tangential direction with respect to the roller body 61a 'of the heating roller 61'. In this embodiment, the extending member 19 extends obliquely with respect to the horizontal plane. The extension member 19 is fixed to a support member 68 provided in the fixing device housing 67 by a fixing member 20 provided at the root end 19b.

  The second magnet 17 is fixed to the support member 68 at a position facing the first magnet 16 (a position opposite to the heating roller 61 ′ of the first magnet 16). The first magnet 16 and the second magnet 17 have the same poles facing each other and repel each other. By this repulsive force, the thermistor element 15 is biased to the outer peripheral surface of the roller body 61a 'of the heating roller 61'.

  The extension member 19 may or may not give an elastic force to the heating roller 61 '. However, when the elastic force is applied, the elastic force of the extension member 19 is preferably smaller than the repulsive force of the first magnet 16 and the second magnet 17.

(9) Other Embodiments Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the invention.

In particular, features of a plurality of embodiments may be appropriately combined.
Although the halogen lamp is used as the heat source in the embodiment, a planar heating element may be used.
In the above-described embodiment, one thermistor is arranged at the longitudinal center of the surface of the heating roller, but the number and position of the thermistors are not limited.
Although the thermistor is used in the embodiment, the temperature detection element may be a thermocouple or a platinum resistance thermometer.

  The present invention can be widely applied to a fixing device and an image forming apparatus using the same.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image reading apparatus 3 Image forming apparatus main body 4 Extension member 4a Tip 4a 'Tip 4b Root end 4b' Root end 5 Thermistor element 6 Magnet 6 'Magnet 6a' Surface 7 Insulator 8 Fixing member 9 Extension member 9a Tip 9b Root end 10 Rotating member 11 Shaft 12 Extension member 12b Root end 13 Fixing member 14 Extension member 14a Tip 14b Root end 15 Thermistor element 16 First magnet 17 Second magnet 19 Extension member 19a Tip 19b Root end 20 Fixing member 21 Image Reading unit 22 Document cover 23 Light source 24 Reflective mirror 25 Scanner unit 26 Platen glass 31 Case 32 Image forming unit 33 Fixing device 34 Paper transport unit 35 Paper feed cassette 36 Manual paper feed tray 37 Paper discharge unit 40 Photosensitive drum 41 Charger 42 exposure head 43 developing device 44 transfer roller 45 cleaning Developing roller main body 51 developing roller 52 supply roller 53 first toner chamber 54 second toner chamber 55 first stirring member 56 second stirring member 57 blade 61 heating roller 61 'heating roller 61a roller body 61a' roller body 61b halogen lamp 63 Pressure roller 64 Motor 65 Nip part 67 Fixing device housing 68 Support member 68 ′ Support member 71 Printer control board 72 High voltage power source for transfer 73 High voltage power source for development 74 High voltage power source for charging 75 High voltage power source for cleaner 76 Heater drive circuit 78 Motor Drive circuit 81 Tonania end sensor 83 Temperature detection member 83 'Temperature detection member 85 Rotating member 86 Shaft

Claims (6)

A fixing device used in an image forming apparatus,
A heating roller;
A temperature detection member for detecting the temperature in contact with the heating roller;
A magnetic member that presses the temperature detection member against the heating roller by magnetic action;
A fixing device provided with The heating roller is made of a magnetic material,
The fixing device according to claim 1, wherein the magnetic member includes a first magnetic member that presses the temperature detection member against the heating roller by attracting the heating roller.   The magnetic member includes a first magnetic member and a second magnetic member disposed so as to repel each other with respect to the first magnetic member, and the first magnetic member and the second magnetic member The fixing device according to claim 1, wherein the temperature detection member is pressed against the heating roller by a repulsive force.   The first magnetic member has a curved surface along the circumferential surface of the heating roller, and the curved surface and the circumferential surface of the heating roller in a state where the temperature detection member is pressed against the heating roller. The fixing device according to claim 2, wherein the temperature detection member is sandwiched between the two.   5. The fixing device according to claim 2, further comprising a rotating member having a first end to which the first magnetic member is fixed and a second end that is rotatably supported. 6.   An image forming apparatus comprising the fixing device according to claim 1.

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