JP2006227349A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of failure such as an image noise by eliminating toner or paper dust stuck to a peeling pawl in a fixing device with the peeling pawl disposed in proximity to a fixing roller. <P>SOLUTION: The fixing device heats and pressurizes paper S with an unfixed toner image transferred thereto by a fixing roller 31 and a pressurizing roller 32 to perform fixing process, then peels off the paper S from the circumferential surface of the fixing roller 31 by a peeling pawl 36 installed in proximity to and in non contact with the circumferential surface of the fixing roller 31. The fixing device is provided with a supporting member 37 supporting the peeling pawl 36 slidably, a driving means abutting and separating the peeling pawl 36 on and from the circumferential surface of the fixing roller 31, and a control means 12 controlling the driving means. The control means 12 carried out control so that the peeling pawl 36 abuts on the circumferential surface of the fixing roller 31 by the driving means in a paper non passing time when the paper S is not passed through a fixing nip part N. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine, and more particularly, a fixing device that fixes an image on a recording medium using a heating roller and a pressure roller, and an image forming apparatus including the fixing device. It is about.

  In the image forming apparatus, a fixing roller method, a heat fixing belt method, or the like is adopted as a fixing device that heats and fixes a recording medium carrying a toner made of heat-meltable resin.

  A fixing roller type fixing device includes a heating rotator provided with a heating element such as a halogen heater inside, and a pressure rotator that is pressed against the heating rotator, and a fixing nip portion that is a pressure contact portion of the pair of rotating bodies By passing a recording medium such as paper, the toner image carried on the recording medium is heated and melted and then discharged. The recording medium discharged from the fixing nip portion is peeled off from the surface of the heating rotator by a peeling member such as a separation claw.

  When a peeling member such as a separation claw is brought into contact with the outer peripheral surface of the heating rotator, the heating rotator may be damaged or image noise may be generated. As a method of avoiding this, there is a method in which the peeling member is arranged in a non-contact manner while being separated from the outer peripheral surface of the heating rotator.

The fixing device described in Patent Document 1 includes a plurality of separation claws that are in close contact with the heating roller and peel off the recording medium, a support member that supports the separation claws, a surface of the fixing roller, and a plurality of separation claws. And adjusting means for individually adjusting the gap. The gap between the surface of the fixing roller and the plurality of separation claws is always fixedly held at a predetermined interval.
JP-A-8-87197

  In an image forming apparatus, particularly a color image forming apparatus, generally, a multicolor toner image such as a photograph or a graph formed on a recording medium has a wider surface than a monochromatic toner image and a multicolor toner. The image formation thickness is larger than that of a monochromatic toner image.

  In a color image forming apparatus, a recording medium subjected to a special coating process may be used in order to make a color image clear. Furthermore, in order to add gloss to a color image, a high fixing temperature is set and a conveyance speed of a recording medium is reduced.

  In a fixing device that performs such color image processing, a fixing nip portion in a state where the toner on the recording medium is not solidified after the multicolor unfixed toner held on the recording medium is heated and melted by the fixing device. It is made to peel from the outer peripheral surface of a heating rotary body by the non-contact-state peeling member. A similar fixing process is also performed in the monochrome image forming apparatus.

  In the case of a peeling member supported in a non-contact state, the recording medium can be peeled stably by disposing the tip of the peeling member close to the outer peripheral surface of the heating rotator. However, due to the proximity of the release members, toner and paper dust are likely to adhere to the release members due to an increase in the number of printed sheets and a recording medium jam, and as a result, defects such as image noise may occur. there were.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in a conventional fixing device, stabilize the peeling of a recording medium after fixing processing, and prevent the occurrence of defects such as image noise.

  The object of the present invention is achieved by the following invention.

  According to the first aspect of the present invention, the recording medium on which the unfixed toner image is transferred by the heating rotator and the pressure rotator is heated and pressed to fix the recording medium, and then contacted with the outer peripheral surface of the heating rotator. In a fixing device that peels a recording medium from an outer peripheral surface of the heating rotator by a separating member disposed in proximity, a support member that supports the peeling member in a swingable manner, and an outer peripheral surface of the heating rotator. And a control means for controlling the drive means. The control means passes the recording medium to a recording medium heating / pressing position by the heating rotator and the pressure rotator. In the fixing device, the driving unit controls the peeling member to come into contact with the outer peripheral surface of the heating rotating body when the sheet is not passed.

  According to a second aspect of the present invention, the time for bringing the peeling member into contact with the heating rotator is a time during which the toner adhering to the peeling member can be melted. Device.

  According to a third aspect of the present invention, the control means is configured such that the heating rotator is driven by the driving means when the recording medium does not pass through a heating / pressing position of the recording medium by the heating rotator and the pressurizing rotator. The fixing device according to claim 1, wherein the fixing device is controlled to rotate in a direction opposite to that during paper passing.

  According to a fourth aspect of the present invention, in the image forming apparatus comprising the image forming means, the recording medium conveying means, and the fixing device according to any one of the first to third aspects, the control means includes a predetermined number of print processes, a predetermined number of print processes, The image forming apparatus is characterized in that the image forming process is performed after either the image forming process or the jam process is finished.

  According to the fixing device of the present invention, the following excellent effects can be obtained.

  According to the first aspect of the present invention, the peeling member is brought into contact with the outer peripheral surface of the heating rotator when the recording medium does not pass through the heating and pressurizing position of the recording medium by the heating rotator and the pressure rotator. As a result, foreign matters such as paper dust and toner adhering to the peeling member are returned to the outer peripheral surface of the heating rotator and cleaned. The foreign matter returned to the outer peripheral surface of the heating rotator is removed by the cleaning means.

  According to the second aspect of the present invention, the time when the peeling member is brought into contact with the heating rotator is set to the time when the toner attached to the peeling member can be melted. Foreign matter is reliably attached to the outer peripheral surface of the heating rotator and removed by the cleaning means.

  According to the invention of claim 3, when the recording medium does not pass through the heating and pressurizing position of the recording medium by the heating rotator and the pressurizing rotator, the direction opposite to the time when the heating rotator is passed by the driving means when the recording medium is not passed. By driving the rotary member to rotate, foreign matters such as paper dust and toner adhering to the peeling member are returned to the outer peripheral surface of the heating rotator and cleaned.

  According to the invention of claim 4, the recording medium on which the image is formed by the image forming means and the recording medium conveying means is fixed by the fixing device according to claims 1 to 3, and is soiled by paper dust or toner. No high quality images are provided. In particular, in a color image forming apparatus that forms a multi-color toner image on a recording medium and sets a high fixing temperature in order to add gloss, a high-quality image free from contamination by paper dust or toner is provided.

  Embodiments of the present invention will be described below. The description in this column does not limit the technical scope of the claims or the meaning of terms.

[Image forming apparatus]
FIG. 1 is a configuration diagram of an image forming apparatus A including a fixing device according to the present invention.

  The image forming apparatus A is called a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-like intermediate transfer member 6, a sheet feeding device 20, and a fixing device described later. 30 or the like.

  On the upper part of the image forming apparatus A, an image reading apparatus B is installed. The document placed on the document table is scanned and exposed by the optical system of the document image scanning exposure apparatus of the image reading apparatus B, and read by the line image sensor. The analog signal photoelectrically converted by the line image sensor is subjected to analog processing, A / D conversion, shading correction, image compression processing and the like in the image processing unit, and then input to the exposure means 3Y, 3M, 3C, 3K. .

  The image forming unit 10Y that forms a yellow (Y) image includes a charging unit 2Y, an exposure unit 3Y, a developing device 4Y, and a cleaning unit 5Y disposed around a photosensitive drum 1Y as an image carrier. The image forming unit 10M that forms a magenta (M) color image includes a photosensitive drum 1M as an image carrier, a charging unit 2M, an exposure unit 3M, a developing device 4M, and a cleaning unit 5M. An image forming unit 10C for forming a cyan (C) color image includes a photosensitive drum 1C as an image carrier, a charging unit 2C, an exposure unit 3C, a developing device 4C, and a cleaning unit 5C. The image forming unit 10K that forms a black (K) image includes a photosensitive drum 1K as an image carrier, a charging unit 2K, an exposure unit 3K, a developing device 4K, and a cleaning unit 5K. The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure unit 3C, and the charging unit 2K and the exposure unit 3K constitute a latent image forming unit.

  4Y, 4M, 4C, and 4K are developing devices that contain a two-component developer composed of a small particle size toner of yellow (Y), magenta (M), cyan (C), and black (K) and a carrier.

  The intermediate transfer body 6 is wound around a plurality of rollers and is rotatably supported.

  The images of the respective colors formed by the image forming units 10Y, 10M, 10C, and 10K are sequentially transferred (primary transfer) and synthesized by the primary transfer units 7Y, 7M, 7C, and 7K on the rotating intermediate transfer body 6. A color image is formed.

  A recording medium (hereinafter referred to as “paper”) S stored in a paper storage unit (paper cassette) 21 of the paper supply device 20 is supplied by a paper supply unit (first paper supply unit) 22 and is supplied by a paper supply roller. 23, 24, 25A, 25B, registration rollers (second paper feed unit) 26, etc., are conveyed to secondary transfer means (transfer roller) 9, and a color image is transferred onto paper S (secondary transfer). .

  It should be noted that the three-stage paper storage units 21 arranged vertically in the vertical direction below the image forming apparatus A have substantially the same configuration, and thus are denoted by the same reference numerals. Also, the three-stage paper feeding means 22 has almost the same configuration, and therefore is given the same reference numeral. The paper storage unit 21 and the paper supply means 22 are collectively referred to as a paper supply device 20.

  The size and paper type of the paper S stored in the paper storage unit 21 are displayed on the display screen of the operation unit 11 and are arbitrarily selected and set. It is also possible to automatically set the size of the paper S according to the document size and the copy magnification.

  The sheet S on which the color image has been transferred is sandwiched by the fixing device 30, and the color toner image (or toner image) on the sheet S is fixed by applying heat and pressure, and is fixed on the sheet S. Discharged.

  The sheet S that has passed through the fixing processing position of the fixing device 30 is peeled off from the surface of the fixing roller (heated rotating body) 31 by a peeling member (hereinafter referred to as a separation claw) 36, and is sandwiched and transported by a pair of transport rollers 38. The paper is discharged from a paper discharge roller 27 provided in the paper discharge conveyance path and placed on a paper discharge tray 28 outside the apparatus.

  On the other hand, after the color image is transferred to the sheet S by the secondary transfer unit 9, the residual toner is removed by the cleaning unit 8 from the intermediate transfer body 6 that has separated the curvature of the sheet S.

  In the case of reversely discharging the fixed sheet S, the sheet S passes through the conveyance path on the right side of the branch plate 29 arranged at the middle branch point between the fixing device 30 and the sheet discharge roller 27 and is conveyed downward. After being transported to the path r1 (reverse transport path), it is transported in reverse, passes through the transport path r2 on the left side of the branch plate 29, and is discharged out of the apparatus by the paper discharge roller 27.

  When copying on both sides of the paper S, after fixing the image formed on the first surface of the paper S, the paper S is branched from the paper discharge conveyance path by the branch plate 29, and the lower conveyance path r1 is further conveyed. After being introduced into the path r3, the sheet is conveyed in the reverse direction, conveyed to the conveyance path r4, detoured upward, and conveyed by the paper feed roller 25B.

  The sheet S is formed on both sides by the image forming means 10Y, 10M, 10C, and 10K with images of each color, heated and fixed by the fixing device 30, and discharged to the outside by the paper discharge roller 27.

  In the description of the image forming apparatus A, the color image formation has been described. However, the present invention includes a case of forming a monochrome image.

[Overall configuration of fixing device]
Hereinafter, the fixing device 30 of the image forming apparatus A will be described.

  FIG. 2 is a cross-sectional view showing an embodiment of the heating roller type fixing device 30.

  The fixing device 30 includes a fixing roller 31 heated by a heating source 33, a pressure roller (pressure rotating body) 32 heated by a heating source 34, and the like.

  Around the fixing roller 31, a cleaning roller 351, a cleaning unit 35 including a cleaning web 352, a separation claw 36, a temperature detection unit (temperature sensor) TS 1, a thermostat for preventing abnormal temperature (not shown), and the like are arranged. Also around the pressure roller 32, a temperature detecting means (temperature sensor) TS2, a thermostat for preventing abnormal temperature (not shown), and the like are arranged.

[Fixing roller]
A halogen lamp, induction heating means, or the like is used for the heating sources 33 and 34.

  The fixing roller 31 includes a heat conductive substrate (core metal) 311, an elastic layer 312, a coating layer 313, and the like.

  The temperature sensor TS1 detects the surface temperature of the fixing roller 31. The control means controls the surface temperature of the fixing roller 31 to a predetermined temperature based on the detection signal of the temperature sensor TS1.

  When the sheet S is introduced into the fixing nip portion (heating and pressing position) N where the fixing roller 31 and the pressure roller 32 are in pressure contact, the heat of the fixing roller 31 heated by the heating source 33 is applied to the sheet S, The toner image t on the paper S is fixed by heating.

  The fixing roller 31 is a cylindrical member having an outer diameter of 20 to 70 mm, which includes a heat conductive base 311, an elastic layer 312, and a coating layer 313. As the cylindrical heat conductive substrate 311, an aluminum material having good heat conductivity is mainly used, and carbon steel, heat resistant glass, or the like is also used. The heat conductive substrate 311 has a required mechanical strength and a thickness (wall thickness) of 0.8 to 10 mm.

  The elastic layer 312 is formed of synthetic rubber such as silicone rubber or fluorine rubber, for example. Further, in order to cope with speeding up of image formation, a method of improving thermal conductivity by blending 5-30% by mass of a metal oxide powder such as silica, alumina, magnesium oxide or the like as a filler in the synthetic rubber is preferable. . The mixed filler is preferably a highly conductive one like the conductive carbon black. By doing so, the electrical resistance (volume resistivity) of the elastic layer 312 can be easily set low. The elastic layer 312 has a thickness (wall thickness) of 0.3 to 3 mm, preferably 1 to 3 mm, and a rubber hardness of 5Hs to 30Hs, which is a JIS-A rubber hardness.

  In order to improve the releasability from the toner on the outer side (outer peripheral surface) of the elastic layer 312, a 20 to 80 μm thick PFA (fluororesin) tube or a fluororesin (PFA or PTFE) paint is used. A heat-resistant coating layer 313 having a good thermal conductivity and a heat-resistant coating layer 313 is provided which is applied with 20 to 100 μm, or formed with silicone rubber or fluororubber having a layer thickness of 20 to 500 μm. The covering layer 313 improves the releasability with the toner and enhances the durability of the elastic layer 312.

[Pressure roller]
A pressure roller 32 as a lower cylindrical fixing member that forms a pair with the upper fixing roller 31 is a cylindrical member, and includes a heat conductive base 321, an elastic layer 322, and a coating layer 323. The constituent members of the pressure roller 32 are formed with substantially the same material, characteristics, and dimensions as the constituent members of the fixing roller 31.

  For example, a thermally conductive substrate 321 using STKM having a thickness of 1 to 3 mm, and a sponge-like thickness using, for example, a silicone rubber layer, a fluorine rubber layer, or a foamed material of silicone rubber on the outer peripheral surface of the thermally conductive substrate 321. (Thickness) A roller having an outer diameter of about 30 to 700 mm formed by an elastic layer 322 made of a thick rubber layer having a thickness of 0.3 to 5 mm and a rubber hardness of 30 Hs to 70 Hs (JIS-A rubber hardness). Is done. On the outer side (outer peripheral surface) of the elastic layer 322, a coating layer 323 is formed that covers a tube of heat-resistant fluororesin such as PFA or PTFA having releasability. A planar fixing nip portion N is formed between the upper fixing roller 31 rotatably supported at the fixed position and the lower pressure roller 32 pressed against the fixing roller 31 by being spring-biased. The image t is fixed.

  The sheet S that has passed through the fixing nip N of the fixing device 30 is separated from the outer peripheral surface of the fixing roller 31 by the separation claw 36. A conveyance roller pair 38 including a driving roller 38A and a driven roller 38B is disposed downstream of the fixing nip N in the sheet conveyance direction.

[Peeling means]
FIG. 3A is a partial cross-sectional view showing the configuration of the peeling means showing the embodiment of the present invention.

  A plurality of separation claws 36 are arranged on a shaft 371 of a support member 37 fixed along the outer peripheral surface of the fixing roller 31, and are supported so as to be able to swing and rotate. The separation claw 36 is urged counterclockwise about the shaft 371 by the urging force of the tension spring 372 stretched between the top part 36 a of the separation claw 36 and the top part 37 a of the support member 37.

  The separation claw 36 has a claw tip 36b facing the outer peripheral surface of the fixing roller 31 on one side (lower right in the figure) of the rotation center, and protrusions 36c and 36d on the other side (left in the figure). Has been established.

  A screw member 373 is screwed to the support member 37. By rotating the screw member 373, the tip end portion of the screw member 373 comes into contact with the protruding portion 36c on the side of the separation claw 36, and the separation claw 36 is rotated counterclockwise about the shaft 371. The receiving member 374 receives the lower surface of the protruding portion 36d and restricts the counterclockwise rotation of the separation claw 36.

  A gear 375 fixed to the rotating shaft of the motor M installed on the support member 37 meshes with a gear formed on the outer periphery of the receiving member 374. By driving the motor M, the gear 375 rotates the receiving member 374. The rotating receiving member 374 is screwed into the fixed screw member 373, moves in the axial direction of the screw member 373, and is locked at a predetermined position.

  Therefore, the screw member 373 moves the position of the claw tip portion 36b of the separation claw 36 by changing the height by a rotation operation, so that the gap between the claw tip portion 36b of the separation claw 36 and the outer peripheral surface of the fixing roller 31 is changed. Adjust the amount Δ.

  The gap amount Δ between the claw tip 36b of the separation claw 36 and the outer peripheral surface of the fixing roller 31 is set in consideration of the following conditions.

  If the gap amount Δ is a value larger than necessary, it is difficult to separate the paper S wound around the fixing roller 31 from the outer peripheral surface of the fixing roller 31, which may cause a jam.

  If the gap amount Δ is too small and is in contact with the outer peripheral surface of the fixing roller 31, the release agent on the outer peripheral surface of the fixing roller 31 is scraped off to the claw tip portion 36 b of the separation claw 36. It collects and generates the so-called oil dripping phenomenon.

  The value of the gap amount Δ is preferably set within a range of 0.05 to 2 mm.

  FIG. 3B is a partial cross-sectional view showing a dirt state of the claw tip 36 b of the separation claw 36.

  The claw tip 36 b of the separation claw 36 is arranged in a counter shape with respect to the outer peripheral surface of the fixing roller 31 that rotates in the clockwise direction shown in the figure, and peels off the paper S adhering to the outer peripheral surface of the fixing roller 31.

  The separation claw 36 supported in a non-contact state facing the outer peripheral surface of the fixing roller 31 separates the sheet S by placing the claw tip 36b of the separation claw 36 close to the outer peripheral surface of the fixing roller 31. . However, due to the proximity of the separation claw 36, toner and paper dust easily adhere to the separation claw 36 due to an increase in the number of printed sheets and jamming of the paper S. As a result, defects such as image noise occur. There was something to do.

  FIG. 3C is a partial cross-sectional view showing a dirt removal state of the claw tip 36 b of the separation claw 36.

  The operation of removing the toner and paper dust adhering to the separation claw 36 is performed by removing the separation claw 36 from the outer periphery of the fixing roller 31 when the paper S does not pass through the paper heating and pressing position by the fixing roller 31 and the pressure roller 32. By bringing them into contact with the surface, foreign matters such as paper dust and toner adhering to the separation claw 36 are returned to the outer peripheral surface of the fixing roller 31 for cleaning.

  The receiving member 374 that descends by driving the motor M is detached from the lower surface of the protruding portion 36d of the separation claw 36, and the regulation of the separation claw 36 is released. By releasing the restriction, the separation claw 36 is rotated counterclockwise about the shaft 371 by the urging force of the tension spring 372.

  By rotating the fixing roller 31 counterclockwise in the drawing, the claw tip 36b of the separation claw 36 is converted into a trail type with respect to the outer circumferential surface of the fixing roller 31, and the outer circumferential surface of the fixing roller 31 and the separation claw 36 are separated. Foreign matter such as paper dust and toner held in the gap with the claw tip 36b is returned to the outer peripheral surface of the fixing roller 31 and cleaned. The foreign matter returned to the outer peripheral surface of the fixing roller 31 is removed by the cleaning unit 35.

  FIG. 4 is a block diagram showing the control of the separation claw 36 and the fixing roller 31.

  The control unit 12 determines the toner melting time by selecting and setting color image formation, single-color or multi-color image formation, paper type, gloss processing, and the like in the operation unit 11 of the image forming apparatus A. The time for which the claw tip 36b is brought into contact with the outer peripheral surface of the fixing roller 31 by swinging and rotating the separation claw 36 is a toner melting time during which the toner attached to the separation claw 36 can be melted.

  When a jam detection signal is issued in the paper feeding means or the paper conveying means, when a series of image forming processes are completed, when a predetermined number of printed sheets is processed, etc., the control means 12 The fixing roller 31 is driven to rotate in reverse, the separation claw 36 is brought into contact with the outer peripheral surface of the fixing roller 31, and foreign matters such as paper dust and toner adhering to the claw tip 36 b of the separation claw 36 are brought to the outer peripheral surface of the fixing roller 31. Return and clean. The foreign matter returned to the outer peripheral surface of the fixing roller 31 is removed by the cleaning unit 35.

  When all of these cleaning processes are completed, the control unit 12 returns the fixing device 30 to the initial state shown in FIG.

In the color image forming apparatus shown in FIG. 1, when forming a multilayer color toner image t having a maximum toner adhesion amount of the toner image t formed on the paper S exceeding, for example, 7 g / m ² , conventionally, toner adhesion The problem that foreign matter such as toner and paper dust adheres to the fixing roller 31 which has been generated as the amount increases is solved by the present invention, and a high-quality image is provided.

  Even when the fixing temperature is raised to improve the glossiness of the color toner image t or the conveyance speed of the recording medium is lowered, the color toner image t on the fixing roller 31 is sufficiently melted. The problem of foreign matter such as toner and paper dust adhering to the toner is solved, and a high-quality image is provided.

  In the embodiment of the present invention, the fixing device mounted on the color image forming apparatus has been described. However, the present invention is also applicable to a single-color or multi-color copying machine, a facsimile, a printer, and a multifunction machine having these functions. .

  In the present invention, the heating rotator is not limited to the fixing roller, but can be applied to a fixing belt and a fixing film.

1 is a configuration diagram of an image forming apparatus including a fixing device according to the present invention. FIG. 3 is a cross-sectional view showing an embodiment of a fixing device of a heating roller type. Sectional drawing which shows the structure of the peeling means which shows embodiment of this invention, the nail | claw tip part dirt state of a separation nail, and the dirt removal state of the nail | claw tip part of a separation claw. The block diagram which shows control of a separation nail and a fixing roller.

Explanation of symbols

30 Fixing Device 31 Fixing Roller (Heating Rotator)
32 Pressure roller (Pressure rotating body)
33, 34 Heating source (heater)
35 Cleaning means 36 Peeling member (separation claw)
36b Claw tip 37 Support member 371 Shaft 372 Tension spring 373 Screw member 374 Receiving member A Image forming apparatus S Recording medium (paper)
Δ Clearance

Claims (4)

The recording medium on which the unfixed toner image is transferred by the heating rotator and the pressure rotator is heated and pressed to fix the recording medium, and then recorded by a peeling member disposed in close contact with the outer peripheral surface of the heating rotator. In the fixing device for peeling the medium from the outer peripheral surface of the heating rotator,
A support member for swingably supporting the peeling member, a driving means for bringing the peeling member into contact with and separating from the outer peripheral surface of the heating rotator, and a control means for controlling the driving means,
The control means applies the peeling member to the outer peripheral surface of the heating rotator by the driving means when the recording medium does not pass through the heating / pressing position of the recording medium by the heating rotator and the pressure rotator. A fixing device which is controlled to contact. The fixing device according to claim 1, wherein the time for bringing the peeling member into contact with the heating rotator is a time during which the toner attached to the peeling member can be melted. The control means is configured such that when the recording medium does not pass through the heating / pressing position of the recording medium by the heating rotator and the pressurizing rotator, the driving means causes the heating rotator to pass in a direction opposite to the time of passing the sheet. The fixing device according to claim 1, wherein the fixing device is controlled to rotate. An image forming apparatus comprising: an image forming unit; a recording medium conveying unit; and the fixing device according to claim 1.
The image forming apparatus according to claim 1, wherein the control unit performs after a predetermined number of printing processes, a predetermined image forming process, or a jam process.

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