JP2018013647A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that can reduce depletion of a lubricant at a sliding part between an inner peripheral surface and a contact member of the fixing device, and an image forming apparatus.SOLUTION: When the cumulative number of prints reaches a threshold (for example, 10,000 prints) (YES in S1), a fixing device checks the temperature of a fixing belt after the end of a fixing operation (S3), and when the temperature of the fixing belt is equal to or lower than a prescribed temperature, performs a fixing belt temperature raising operation (S6). When the temperature of the fixing belt is raised to the prescribed temperature or higher, the fixing device executes a reverse rotation mode (S7) to re-attach a lubricant accumulated on an exit side of a nip part to the fixing belt. When the fixing belt is rotated by one revolution, the fixing device ends the reverse rotation mode (S9).SELECTED DRAWING: Figure 10

Description

  The present invention relates to a fixing device and an image forming apparatus.

  Conventionally, a pressure roller, which is a pressure member, is pressed against a contact member in contact with the inner peripheral surface of the fixing belt while a fixing belt, which is an endless fixing member having an inner peripheral surface coated with a lubricant, is sandwiched between the nip and the nip. A fixing device that forms a portion is known. In this fixing device, the fixing belt is rotated together with the pressure roller that is driven to rotate, and the recording material is passed through the nip portion to fix the image on the recording material.

  In Patent Document 1, as the fixing device, lubrication is performed in which the fixing belt is rotated in the same direction as when the image is fixed to the recording material in a state where the pressure applied to the fixing belt between the pressure roller and the contact member is reduced. There is described one that executes the agent movement mode at a predetermined timing. As a result, the lubricant staying at the inlet side of the nip part returns to the sliding part between the contact member and the inner peripheral surface of the fixing belt, and depletion of the lubricant at the sliding part between the contact member and the inner peripheral surface of the fixing belt is suppressed. It is described that the increase in the frictional resistance between the contact member and the fixing belt can be suppressed.

  However, the fixing device described in Patent Document 1 cannot sufficiently suppress the depletion of the lubricant in the sliding portion between the contact member and the inner peripheral surface of the fixing belt, and increases the frictional resistance between the contact member and the fixing belt. There was a possibility that it could not be suppressed.

  In order to solve the above problems, the present invention forms a nip portion by pressing a pressure member through the fixing member to a contact member that contacts an inner peripheral surface of the endless fixing member with a lubricant interposed therebetween. In the fixing device that rotates the pressure member to rotate the fixing member and passes the recording material through the nip portion to fix the image on the recording material, the image is recorded at a predetermined timing. A reverse rotation mode is executed in which the fixing member is rotated in a direction opposite to the rotation direction when the toner image is fixed.

  According to the present invention, it is possible to suppress the depletion of the lubricant in the sliding portion between the inner peripheral surface of the fixing member and the contact member.

1 is a schematic configuration diagram of a printer according to an embodiment. FIG. FIG. 3 is a schematic explanatory diagram of a fixing device. Explanatory drawing of the prior art example of the fixing device of 2 halogen heater structure. FIG. FIG. 3 is an explanatory diagram of a positional relationship in the longitudinal direction between each heater provided in the fixing device and a sheet to be fixed. FIG. 4 is an explanatory diagram of a positional relationship in the longitudinal direction of each heater in the vicinity of both ends provided in the fixing device. Block diagram for explaining an example of the control system of the present embodiment FIG. 6 is a diagram for explaining the behavior of a fixing belt during a fixing operation. The enlarged view of the part enclosed with the continuous line A of FIG. The figure which shows an example of the flowchart of reverse rotation mode execution. FIG. 6 is a diagram for explaining the behavior of the fixing belt when the fixing belt is rotated in a direction opposite to the rotation direction during the fixing operation. The perspective view which shows a stay. The figure which shows the positioning hole provided in the stay. (A) is a side view which shows a mode that a nip formation member is assembled | attached to a stay, (b) is a side view which assembled | attached the nip formation member to the stay. The perspective view which assembled | attached the nip formation member to the stay. (A) is a figure which shows a mode that the fixing belt was rotated forward (rotation direction at the time of a fixing operation), (b) is a figure which shows a mode that the fixing belt was reversely rotated. FIG. 6 is a view showing a periphery of a nip portion of a fixing device according to a first modification.

Hereinafter, an embodiment of an electrophotographic color printer (hereinafter referred to as a printer 200) will be described as an image forming apparatus including a fixing device to which the present invention is applied.
FIG. 1 is a schematic configuration diagram of a printer 200 according to the present embodiment.
The printer 200 shown in FIG. 1 is a tandem type color printer in which image forming units for forming a plurality of color images are juxtaposed along the extending direction of a transfer belt 11 as an intermediate transfer member. However, the image forming apparatus to which the fixing device of the present embodiment can be applied is not limited to this method, and can be applied not only to a printer but also to an image forming apparatus such as a copying machine or a facsimile machine.

The printer 200 is a tandem in which photosensitive drums 20Y, 20C, 20M, and 20B as image carriers that can form images corresponding to colors separated into yellow, cyan, magenta, and black are arranged in parallel. Structure is adopted.
In the printer 200, the transfer belt 11 is an endless belt in which a visible image formed of a toner image formed on each photoconductive drum 20Y, C, M, Bk can move in the direction of arrow A1 while facing the photoconductive drum. Primary transfer. By executing this primary transfer process, the images of the respective colors are superimposed and transferred, and then transferred to the sheet-like paper P as a recording material by performing a secondary transfer process.

  Around each photosensitive drum 20, an apparatus for image forming processing is arranged according to the rotation of the photosensitive drum 20. The photosensitive drum 20Bk that performs black image formation will be described as a representative. The charging device 30Bk, the developing device 40Bk, the primary transfer roller 12Bk, and the cleaning device 50Bk that perform image forming processing along the rotation direction of the photosensitive drum 20Bk are arranged. Has been. The optical writing device 8 is used for optical writing using the writing light Lb performed after uniform charging by the charging device 30Bk.

  In the superimposing transfer on the transfer belt 11, the toner images formed on the photosensitive drums 20 </ b> Y, 20 </ b> C, 20 </ b> M, and Bk are overlapped at the same position on the transfer belt 11 in the process in which the transfer belt 11 moves in the direction A <b> 1. Is transcribed. For this reason, the primary transfer is performed by applying a voltage from the primary transfer rollers 12Y, 12C, 12M, and 12B that are disposed to face the photosensitive drums 20Y, 20C, 20M, and 20B with the transfer belt 11 interposed therebetween. The timing is shifted from the upstream side toward the downstream side in the A1 direction.

  The photosensitive drums 20Y, 20C, 20M, and 20K are arranged in this order from the upstream side in the A1 direction in the drawing. Each of the photosensitive drums 20Y, 20C, 20M, and 20Bk is provided in an image station for forming yellow (Y), cyan (C), magenta (M), and black (Bk) images.

  The printer 200 is disposed so as to face four image stations that perform image formation processing for each color, and above the respective photosensitive drums 20Y, 20C, 20M, 20B, 20K, and transfer belts 11 and primary transfer rollers 12Y, 12C, and 12K. A transfer belt unit 10 having M and Bk is provided. There are also a secondary transfer roller 5 that is disposed facing the transfer belt 11 and is driven by the transfer belt 11, and a belt cleaning device 13 that is disposed facing the transfer belt 11 and cleans the transfer belt 11. I have. The optical writing device 8 is also provided so as to face the lower side of the four image stations.

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

  The printer 200 is provided with a sheet feeding device 61 as a sheet feeding cassette on which sheets P conveyed between the transfer belt 11 and the secondary transfer roller 5 are stacked. In addition, the sheet P conveyed from the sheet feeding device 61 is transferred to the secondary transfer portion between the transfer belt 11 and the secondary transfer roller 5 at a predetermined timing in accordance with the toner image formation timing by the image station. A pair of registration rollers 4 that is fed out is provided. Further, a sensor for detecting that the leading edge of the paper P has reached the registration roller pair 4 is also provided.

  Further, the printer 200 includes a contact heating type fixing device 100 as a fixing unit for fixing the toner image on the paper P onto which the toner image has been transferred, and the fixed paper P is discharged to the outside of the printer 200 main body. A discharge roller 7 is provided. In addition, a discharge tray 17 for stacking sheets P discharged to the outside of the main body of the printer 200 by the discharge roller 7 is provided at the upper part of the main body of the printer 200. Further, in the apparatus main body below the paper discharge tray 17, toner bottles 9Y, C, M, and Bk filled with toners of yellow, cyan, magenta, and black are provided.

In addition to the transfer belt 11 and the primary transfer rollers 12Y, C, M, and Bk, the transfer belt unit 10 includes a driving roller 72 and a driven roller 73 around which the transfer belt 11 is wound.
The driven roller 73 also has a function as tension urging means for the transfer belt 11, and the driven roller 73 is provided with urging means using a spring or the like. Such a transfer belt unit 10, the primary transfer rollers 12Y, C, M, and Bk, the secondary transfer roller 5, and the belt cleaning device 13 constitute a transfer device 71.
The paper feeding device 61 is disposed at the lower part of the main body of the printer 200 and has a feeding roller 3 that comes into contact with the upper surface of the uppermost paper P. The uppermost sheet P is fed toward the registration roller pair 4 by rotating the feeding roller 3 counterclockwise in the drawing.

The belt cleaning device 13 provided in the transfer device 71 includes a cleaning brush and a cleaning blade disposed so as to face and contact the transfer belt 11. The belt cleaning device 13 cleans the transfer belt 11 by scraping and removing foreign matters such as residual toner on the transfer belt 11 with a cleaning brush and a cleaning blade.
Further, the belt cleaning device 13 has a discharging means for carrying out and discarding the residual toner removed from the transfer belt 11.

Hereinafter, the fixing device 100 which is a characteristic part of the printer 200 of the present embodiment will be described with reference to the drawings.
FIG. 2 is a schematic explanatory diagram of the fixing device 100.
As shown in FIG. 2, the fixing device 100 includes a fixing belt 101 as a rotatable endless fixing member, and a pressure roller 103 as a driving member that is disposed to face the fixing belt 101 and can rotate. . Further, the fixing belt 101 is moved from the inner peripheral side by the two halogen heaters 102, ie, the first halogen heater 102A and the second halogen heater 102B, which are a plurality of fixing heat sources as heating means for heating the fixing belt 101 at the non-nip portion. It is configured to be directly heated by radiant heat.
Further, in the fixing belt 101 of the fixing device 100 shown in FIG. 2, there is a nip forming member 106 that forms a nip portion with the pressure roller 103 via the fixing belt 101. It slides through the movement assisting member 116. The toner image on the paper P is fixed at the nip portion N by heating and pressing.

Here, in the example shown in FIG. 2, the shape of the portion of the heat transfer assisting member 116 facing the fixing belt 101 is flat, but may be a concave shape or other shapes. In the case of the concave nip portion, the discharge direction of the front end of the sheet is closer to the pressure roller, and the separation is improved, so that the occurrence of jam is suppressed.
Inside the fixing belt 101, a nip forming member 106 disposed to face the pressure roller 103, and an end portion that is integrally provided at both ends of the nip forming member 106 and heats the fixing belt 101 at the nip portion. It has two end heaters 126 as heat sources. Further, the heat transfer assisting member 116 covering the nip forming member 106 and the surface of the end heater 126 facing the inner surface of the fixing belt 101, and the nip forming member 106 are held against the pressure applied from the pressure roller 103. A stay 107 is also provided.
Further, as will be described in detail later, the left end heater 126a and the right end heater 126b, which are the two end heaters 126 provided at the respective ends in the longitudinal direction, are provided independently and have a continuous shape. Absent.

The nip forming member 106, the heat transfer assisting member 116, and the stay 107 all have a length that extends in the width direction of the fixing belt 101 (hereinafter referred to as “longitudinal direction”).
The heat transfer auxiliary member 116 is provided to prevent the heat of each end heater 126 from staying locally, and to actively move the heat in the longitudinal direction to reduce the temperature non-uniformity in the longitudinal direction. Yes.
For this reason, the heat transfer auxiliary member 116 is preferably a material that can transfer heat in a short time, and is preferably a member such as copper, aluminum, or silver having high thermal conductivity. In consideration of cost, availability, thermal conductivity characteristics, and workability, it is most desirable to use copper.
The heat transfer assisting member 116 is fitted and integrated so as to cover the surface of the rectangular parallelepiped nip forming member 106 that faces the inner surface of the fixing belt 101. Here, the integral configuration of the heat transfer assisting member 116 and the nip forming member 106 may be provided by engaging with a claw or the like, but means such as adhesion may be used. In this example, the surface of the heat transfer assisting member 116 that faces the inner surface of the fixing belt 101 is a surface that directly contacts the fixing belt 101 and serves as a nip forming surface.

The fixing belt 101 is composed of a metal belt such as nickel or SUS, an endless belt using a resin material such as polyimide, or a film.
The surface layer of the fixing belt 101 has a release layer such as a PFA or PTFE layer, and has a release property so that toner does not adhere.
There may be an elastic layer formed of a silicone rubber layer or the like between the base material of the fixing belt 101 and the PFA or PTFE layer. When there is no silicone rubber layer, the heat capacity is reduced and the fixability is improved. However, when the unfixed image is crushed and fixed, the minute irregularities on the surface of the fixing belt 101 are transferred to the image and become solid on the image. There may be a problem that a yuzu skin-like gloss unevenness (yuzu skin image) remains. In order to improve this, it is necessary to provide a silicone rubber layer of 100 [μm] or more. Due to the deformation of the silicone rubber layer, minute unevenness is absorbed and the skin image is improved.

The stay 107 has a shape having an upright portion standing upright on the side opposite to the nip portion N side, and a first halogen heater 102A and a second halogen heater 102B as a fixing heat source are arranged with the upright portion separated.
The fixing belt 101 is directly heated by radiant heat from the inner surface side by these two halogen heaters 102.
Further, by disposing each halogen heater 102 on the inner peripheral side of the fixing belt 101, the fixing device 100 including the rotatable endless fixing belt 101 can be easily configured in a compact manner.

The above-described stay 107 as a support member for supporting the nip forming member 106 and the nip portion N is provided inside the fixing belt 101 to prevent the nip forming member 106 that receives pressure from the pressure roller 103 from bending. A uniform nip width can be obtained in the axial direction.
The stay 107 is held and fixed by a flange as a holding member at both ends. Further, a reflection member 109 is provided between the two halogen heaters 102 and the stay 107, and wasteful energy consumption due to the stay 107 being heated by radiant heat from each halogen heater 102 is suppressed.
Here, instead of providing the reflecting member 109, the same effect can be obtained even if the surface of the stay 107 is heat-insulated or mirror-finished.

The pressure roller 103 has an elastic rubber layer 104 on the outer periphery of the cored bar 105, and a release layer (PFA or PTFE layer) on the surface in order to obtain releasability.
The pressure roller 103 is rotated by a driving force transmitted through a gear from a pressure roller driving motor provided in the printer 200 main body. The pressure roller 103 is pressed against the fixing belt 101 by a spring or the like, and has a predetermined nip width when the elastic rubber layer 104 is crushed and deformed.

The pressure roller 103 may be a hollow roller, and the pressure roller 103 may have a heating source such as a halogen heater.
The elastic rubber layer 104 may be solid rubber, but if there is no heater inside the pressure roller 103, sponge rubber may be used. Sponge rubber is more preferable because heat insulation is increased and heat of the fixing belt 101 is less likely to be taken away.

The fixing belt 101 is rotated by the pressure roller 103.
In the example shown in FIG. 2, the pressure roller 103 is rotated by the pressure roller driving motor, and the driving force is transmitted to the fixing belt 101 through the nip portion N, whereby the fixing belt 101 rotates.
The fixing belt 101 is sandwiched and rotated at the nip portion N, and travels while being guided by the flanges at both ends other than the nip portion N.
With the above-described configuration, it is possible to realize a fixing device 100 that is inexpensive and has a fast warm-up.

Here, a conventional fixing device 100 will be described with reference to FIG.
FIG. 3 is an explanatory diagram of a conventional example of a fixing device having two halogen heaters.
As such a fixing device 100, for example, a fixing device described in Patent Document 2 is known.

A conventional fixing device 100 shown in FIG. 3 is arranged on a rotatable endless fixing belt 101, two halogen heaters 102 for heating the fixing belt 101 from the inside, and an inner peripheral side of the fixing belt 101. This is a so-called belt-type fixing device having a nip forming member 106 and a pressure roller 103 that presses a sheet nipped and conveyed by the fixing belt 101 toward the fixing belt 101.
Further, in the fixing device 100, the length and arrangement position of the heat generating portions in the longitudinal direction (direction orthogonal to the endless movement direction of the fixing belt 101) of the two halogen heaters 102 for heating the inner peripheral surface of the fixing belt 101 are different. It is

  However, in this conventional example, since the two halogen heaters 102 are surrounded by the reflecting member 109, the heating efficiency is lowered by the attenuation of radiation due to reflection and the narrowing of the irradiation angle as shown by the bidirectional arrows. To do. Here, the irradiation angle is an angle at which the radiation from each halogen heater 102 directly hits the fixing belt 101. For example, one halogen heater 102 is a central heater that heats the longitudinal center of the fixing belt 101, and the other halogen heater 102 is an end heater that heats the longitudinal end of the fixing belt 101.

On the other hand, there is a market need for image formation on a normal standard paper, for example, a paper having a paper width wider than the A3 longitudinal paper width (297 mm) (so-called nobi paper).
However, for example, in the case where fixability at a paper width up to nobi paper is required, it is necessary to extend the heat generation width of the end heater that heats the end in the longitudinal direction to the end of the nobi paper, and a standard size such as A3 size Overheating of the end of the fixing belt 101 occurs for the paper. In order to prevent this, there is a problem that it is necessary to adjust the productivity, etc., or that a configuration that prevents excessive temperature rise of the non-sheet passing portion such as providing a rotatable shielding member is provided to increase the cost. there were.

Therefore, in the present embodiment, the fixing device 100 is configured as follows.
As shown in FIG. 2, the stay 107 includes a first member 107A and a second member 107B each having a substantially L-shaped cross section.
The first member 107 </ b> A and the second member 107 </ b> B partition the two halogen heaters 102 and are fixed to the nip forming member 106. Further, as shown in FIG. 4, the first member 107A and the second member 107B extend linearly in the longitudinal direction of the heater, and the cross section of the stay 107 is formed in a substantially T-shape.
Since the two halogen heaters 102 are arranged in separate upper and lower regions sandwiching the stay 107, the glass tubes can be heated when the heaters are lit as in the conventional configuration shown in FIG. As a result, heating efficiency does not decrease.

  Further, a reflection member 109 is provided between each halogen heater 102 and the stay 107, and wasteful energy consumption due to the stay 107 being heated by radiant heat from each halogen heater 102 can be suppressed. Here, instead of providing the reflecting member 109, the same effect can be obtained even if the surface of the stay 107 is heat-insulated or mirror-finished.

Here, the heat distribution and arrangement of the two halogen heaters 102 which are heat sources for directly heating the fixing belt 101 of the present embodiment and the two end heaters 126 integrally provided at both ends of the nip forming member 106. The end heat source control method and the like will be described with reference to the drawings.
FIG. 5 is an explanatory diagram of the positional relationship in the longitudinal direction between the heaters provided in the fixing device 100 and the paper to be fixed.

As shown in FIG. 5, the first halogen heater 102 </ b> A is a halogen heater corresponding to a small size paper P such as A4 vertical in which the light distribution distribution of the central portion 102 c in the longitudinal direction of the fixing belt 101 is dense.
The second halogen heater 102B is a halogen heater corresponding to a sheet P of A3 size or the like in which the light distribution at both ends 102d in the longitudinal direction is dense.
In the halogen heaters 102, when the paper P is a small size, only the first halogen heater 102A is turned on, the non-sheet passing portion at the end in the longitudinal direction is heated unnecessarily, or the end of the end due to continuous sheet passing is determined. Overheating is prevented.
The left end heater 126a and the right end heater 126b are arranged so that a part of the heating range in the longitudinal direction overlaps the end of the second halogen heater 102B in the same direction. In other words, the left end heater 126a and the right end heater 126b are arranged so as to compensate for a decrease in heat distribution output at a position corresponding to the extreme end of the sheet width of the second halogen heater 102B.

  Further, as described above, the fixing device 100 includes the fixing heat sources of the first halogen heater 102A and the second halogen heater 102B having different heat distributions in the longitudinal direction as heating means for the fixing belt 101. . Thereby, the heating of the range of the fixing belt 101 corresponding to the paper size of the paper P passing through the inside of the region heated by each end heater 126 can be efficiently performed.

Here, the heat distribution of the second halogen heater 102B and each end heater 126 will be described.
FIG. 6 is an explanatory diagram of the positional relationship in the longitudinal direction of each heater in the vicinity of both ends provided in the fixing device 100, and FIG. 6A is an explanatory diagram of the positional relationship and heat distribution of the second halogen heater 102B. FIG. 6B is an explanatory diagram of the positional relationship and heat distribution of the right end heater 126b.

Normally, the second halogen heater 102B does not output 100% of heat distribution to the target heat distribution amount up to the end of the filament, and the heat distribution output of the end is 50% due to the heat amount sagging. It is common to define up to this point as a heat generating part. Also, each end heater 126 does not output 100% of the target heat distribution amount up to the heater end, and the heat distribution output sags at the end in the longitudinal direction of the heat generation pattern.
For this reason, when a drop in the heat distribution output occurs at the longitudinal boundary between the second halogen heater 102B and each end heater 126, a fixing defect occurs particularly at the end of the paper having a width wider than a standard size such as nobi paper. there is a possibility. For this reason, it is desirable that the end portions where the heat distribution outputs of the second halogen heater 102B and the end heaters 126 become 100% be the boundary positions in the longitudinal direction.

Further, as described above, as the material of the heat transfer auxiliary member 116, a material having high thermal conductivity such as copper or aluminum is used.
By using a material having such a high thermal conductivity, the heat of each halogen heater 102 and each end heater 126 is prevented from staying locally, and the heat is positively moved in the longitudinal direction. Reduces temperature non-uniformity.

However, the heat transfer assisting member 116 and the inner surface of the fixing belt 101 slide, and if the metal material is rubbed against the inner surface of the fixing belt 101 as it is, there is a problem that the coefficient of friction increases and the unit torque increases. For this reason, it is desirable that the facing surface of the heat transfer assisting member 116 facing the fixing belt 101 is smooth, and it is desirable to perform a treatment that reduces the friction coefficient in order to further improve the slidability.
Specifically, it is possible to maintain good sliding between the heat transfer assisting member 116 and the inner surface of the fixing belt 101 by applying a fluorine-based paint or coating such as PFA or PTFE.
Further, in this embodiment, a lubricant such as fluorine grease or silicone oil is applied to the inner surface of the fixing belt 101, and the lubricant is interposed between the heat transfer assisting member 116 serving as a contact member and the inner surface of the fixing belt 101, The sliding torque is reduced.

FIG. 7 is a block diagram illustrating an example of a control system of the present embodiment.
The control unit 90 includes a CPU (Central Processing Unit), a read-only memory (ROM) that stores a control program, a readable / writable memory (RAM) that temporarily stores data, a nonvolatile flash memory, and the like. Yes.
And various arithmetic processes are performed, various drive system apparatus which each apparatus etc. which were connected as shown in FIG. 7 is driven, or it communicates with various sensors.

  Further, the control unit 90 controls the heating of the halogen heaters 102 </ b> A and 102 </ b> B and the end heater 126 based on the detection result of the thermistor 91 that detects the temperature of the fixing belt 101. Further, the control unit 90 executes a reverse rotation mode in which the fixing belt 101 is reversely rotated at a predetermined timing.

FIG. 8 is a diagram for explaining the behavior of the fixing belt 101 during the fixing operation, and FIG. 9 is an enlarged view of a portion surrounded by a solid line A in FIG.
As shown in FIG. 8, the inside of the fixing belt 101 is located on the inlet side of the nip portion N that is upstream of the nip portion N from the nip portion N and on the outlet side of the nip portion N that is downstream of the nip portion N. The lubricant 301 applied to the peripheral surface stays.

  The stagnation of the lubricant 301 on the nip inlet side occurs as follows. The nip portion entrance side is a side on which the fixing belt 101 is drawn into the nip portion N by the rotational driving force of the pressure roller 103. Therefore, the entrance side of the nip portion of the fixing belt 101 is a pulling side, and the inner peripheral surface of the fixing belt is in contact with the upstream end of the heat transfer auxiliary member 116 on the sheet conveyance side. Therefore, the lubricant adhering to the fixing belt 101 is scraped off by the upstream end portion of the heat transfer auxiliary member 116 in the sheet conveyance, and the scraped lubricant 301 stays in the upstream end portion of the sheet conveyance.

  The stagnation of the lubricant 301 on the nip exit side occurs as follows. The nip portion outlet side is bent, and the fixing belt 101 is separated from the heat transfer assisting member 116 as shown in FIG. This is because the fixing belt 101 has a substantially circular shape when not pressed against the heat transfer auxiliary member 116 by the pressure roller 103, and when the nip portion N is formed by being pressed by the pressure roller 103, the pressure is increased. The fixing belt 101 changes from a substantially circular shape to a substantially heart shape by contacting the heat transfer assisting member 116 so that the portion pressed by the roller 103 is recessed. At this time, the inner peripheral surface of the fixing belt 101 is in contact with both ends of the heat transfer auxiliary member 116 in the sheet conveyance direction and the nip portion of the heat transfer auxiliary member 116, and the inlet side and the outlet side of the nip portion are moved by heat. It is separated from the auxiliary member 116. As described above, when the fixing belt rotates, the inlet side of the nip portion becomes the tension side, so that the inner peripheral surface of the fixing belt contacts the heat transfer assisting member 116. However, the nip portion outlet side from which the fixing belt is fed out from the nip portion is not separated from the heat transfer auxiliary member as before because the pulling force as described above does not work, and the heat transfer auxiliary member 116 is downstream in the sheet conveyance direction. It looks like it touches only the end. As a result, on the nip exit side, the fixing belt 101 moves on the surface while sliding with the downstream end of the heat transfer auxiliary member 116 in the paper conveyance direction. At this time, the lubricant 301 adhering to the inner peripheral surface of the fixing belt 101 is scraped by the downstream end of the heat transfer assisting member 116, and the scraped lubricant is removed from the heat transfer assisting member 116, the fixing belt 101, and the like. It stays in the gap during this period.

  Further, when the fixing belt 101 passes through the nip portion N, the fixing belt 101 is strongly pressed against the heat transfer assisting member 116 by the pressure roller 103, so that the lubricant is pushed out to the nip portion outlet side and the inlet side. Since the nip portion inlet side is in contact with the heat transfer assisting member 116 as described above, the lubricant pushed out to the nip portion inlet side adheres to the fixing belt and does not stay. On the other hand, the lubricant pushed out to the nip portion outlet side does not adhere to the fixing belt 101 and the fixing belt 101 moves thermally because the fixing belt 101 is separated from the heat transfer auxiliary member 116 on the nip portion outlet side. It stays in the gap between the auxiliary member 116.

  As described above, the lubricant stays on the inlet side and the outlet side of the nip portion N, so that the lubricant in the sliding portion between the fixing belt and the heat transfer auxiliary member 116 is depleted, and the sliding torque increases. In addition, there is a problem such that the wear of the fixing belt is accelerated.

  Therefore, in this embodiment, the reverse rotation mode in which the fixing belt 101 is reversely rotated is executed at a predetermined timing, and the lubricant staying at the nip portion outlet side is again attached to the inner peripheral surface of the fixing belt. I did it. Hereinafter, it demonstrates concretely using drawing.

FIG. 10 is an example of a flowchart of reverse rotation mode execution.
The lubricant staying at the outlet side of the nip portion increases as the number of printed sheets increases, and accordingly, the amount of lubricant adhering to the inner peripheral surface of the fixing belt 101 decreases. Therefore, the control unit 90 counts the number of printers, and when the cumulative number of printed sheets reaches a threshold (for example, 10,000 sheets) (YES in S1), sets a reverse rotation mode execution flag (S2). In the present embodiment, the cumulative number of prints is used, but when the number of rotations of the pressure roller 103 reaches a threshold value, a reverse rotation mode execution flag may be set.

  At the end of the fixing operation, the controller 90 checks whether or not the reverse rotation mode execution flag is set. If the reverse rotation mode execution flag is set (Yes in S3, Yes in S4), the thermistor 91 detects. The temperature of the fixed fixing belt 101 is checked (S5). When the fixing belt 101 is below the specified temperature (No in S5), the fixing belt temperature raising operation is performed (S6). The fixing belt temperature raising operation is an operation of turning on the halogen heater 102 and the end heater 126 while rotating the fixing belt 101 to raise the fixing belt 101 to a specified temperature. When the fixing belt 101 is at or above the specified temperature (Yes in S5), the reverse rotation mode is started (S7).

  The lubricant 301 has a high viscosity when the temperature is low, and the viscosity decreases as the temperature increases. If the viscosity is high, the retained lubricant 301 is difficult to adhere to the fixing belt 101. Therefore, in this embodiment, the reverse rotation mode is executed in a state where the fixing belt 101 is set to a predetermined temperature or more and the viscosity of the lubricant 301 is reduced. As a result, the lubricant staying on the exit side of the nip portion can be satisfactorily adhered to the fixing belt 101 by the reverse rotation mode.

  When the reverse rotation mode is executed, the control unit 90 controls the pressure roller driving motor 203 to drive the pressure roller 103 in a direction opposite to the rotation direction during the fixing operation. As a result, the fixing belt 101 rotates in the direction opposite to the rotation direction during the fixing operation.

FIG. 11 is a diagram illustrating the behavior of the fixing belt 101 when the fixing belt 101 is rotated in the direction opposite to the rotation direction during the fixing operation.
As shown in FIG. 11, by reverse rotation, the entrance side of the nip portion becomes the side where the fixing belt 101 is successively sent out from the nip portion N by the rotational driving of the pressure roller 103, and the belt bends so that the fixing belt 101 bends. Become the side. On the other hand, the exit side of the nip portion is a side on which the fixing belt 101 is drawn by the rotational driving force of the pressure roller 103 and is a belt tension side. As a result, as shown in FIG. 11, the fixing belt 101 contacts the heat transfer assisting member 116 at the nip exit side. As a result, the lubricant 301 staying at the exit side of the nip portion can be attached to the fixing belt 101 again.

  When the fixing belt 101 rotates once (Yes in S8), the control unit 90 ends the reverse rotation mode, erases the reverse rotation mode execution flag, and resets the number of prints. Even if the reverse rotation amount of the fixing belt 101 is about half a rotation, the staying lubricant on the nip portion outlet side can be reduced. However, by rotating the fixing belt 101 once, the lubricant 301 staying on the nip portion outlet side can be attached to the entire circumference of the fixing belt, which is more effective.

  As described above, in the present embodiment, the lubricant 301 staying at the nip portion outlet side can be adhered to the fixing belt 101 again by performing the reverse rotation mode. Thereby, it is possible to suppress the depletion of the lubricant in the sliding portion between the heat transfer assisting member 116 and the fixing belt 101, and to suppress an increase in sliding resistance over time.

In the above description, even if the reverse rotation mode is performed, the lubricant staying at the nip portion entrance side does not reattach to the fixing belt 101 but remains attached to the heat transfer assisting member 116.
In Patent Document 1, the lubricant staying at the inlet side of the nip portion is made to move the sliding portion between the heat transfer assisting member 116 and the fixing belt 101 by rotating the fixing belt while reducing the pressure applied by the pressure roller. What is returned to is described. However, in Patent Document 1, the lubricant adhering to the fixing belt 101 that has been blocked by the upstream end portion of the heat transfer assisting member 116 on the sliding belt between the heat transfer assisting member 116 and the fixing belt 101. Although it can be returned, the lubricant adhering to the heat transfer assisting member 116 cannot be returned. Therefore, the exhaustion of the lubricant cannot be solved sufficiently.

  Further, in the fixing device described in Patent Document 1, since the fixing belt 101 is rotated by reducing the pressure applied by the pressure roller 103, the fixing belt 101 may slip with respect to the pressure roller 103. For example, if the frictional force between the pressure roller 103 and the fixing belt 101 is different in the axial direction, only one end side in the axial direction slips and the fixing belt 101 is twisted. In the worst case, the fixing belt 101 is twisted. There is a risk of damage. Further, when the sliding resistance between the fixing belt 101 and the heat transfer assisting member 116 is large, there is a possibility that the fixing belt 101 may not be rotationally driven if the pressure applied by the pressure roller 103 is reduced.

  Further, in the configuration described in Patent Document 1, when the lubricant staying at the landing nip entrance side is reduced, the pressing force of the pressure roller 103 is reduced after the reverse rotation mode, and the fixing belt 101 is moved. There is also a problem that the downtime of the apparatus becomes long because the rotation mode is executed.

  Therefore, the heat transfer assisting member 116 can be moved in the sheet moving direction, and in the reverse rotation mode, the heat transfer assisting member 116 is moved upstream in the sheet moving direction, and the heat transfer assisting member 116 is upstream in the sheet moving direction. The lubricant adhering to the part was brought into contact with the fixing belt so that it could be removed. This will be specifically described below with reference to the drawings.

  In the present embodiment, as described above, the heat transfer assisting member 116 is fitted and integrated with the nip forming member 106, so that the nip forming member 106 can be moved in the sheet moving direction. The heat transfer assisting member 116 can be moved in the sheet moving direction.

FIG. 12 is a perspective view showing the stay 107, and FIG. 13 is a view showing a positioning hole 107 c provided in the stay 107.
As shown in FIG. 12, the stay 107 is provided with positioning holes 107c for positioning the nip forming member 106 at three locations in the longitudinal direction. As shown in FIG. 13, each positioning hole 107 c has a rectangular shape that is long in the short direction, which is the paper transport direction. In the present embodiment, each positioning hole 107c has a longitudinal length of 3.1 [mm] and a short length of 4.5 [mm].

  FIG. 14A is a side view showing a state where the nip forming member 106 is assembled to the stay 107, and FIG. 14B is a side view where the nip forming member 106 is assembled to the stay 107. FIG. 15 is a perspective view in which the nip forming member 106 is assembled to the stay 107.

  As shown in FIG. 14A, the nip forming member 106 is provided with positioning bosses 106a at three locations in the longitudinal direction. The positioning boss 106a is formed on a cylinder of φ3 [mm]. As shown by the arrows in FIG. 14A, these positioning bosses 106a are fitted into the positioning holes 107c of the stay 107, so that the nip forming member 106 is fixed to the stay 107 as shown in FIGS. Assembled to. As described above, the diameter of the positioning boss 106a is 3 [mm], whereas the length of the positioning hole 107c in the short direction is 4.5 [mm]. As a result, the nip forming member 106 is attached to the stay 107 so that the nip forming member 106 can move up to 1.5 [mm] in the paper transport direction. As described above, the heat transfer assisting member 116 is attached to the nip forming member 106 by bonding or fitting to the stay 107, and the heat transfer assisting member 116 is integrated with the nip forming member 106 so as to be integrated with the stay 107. Can be moved in the paper transport direction. Both ends of the stay 107 are attached to the side plate of the fixing device.

FIG. 16A is a diagram illustrating a state in which the fixing belt 101 is rotated forward (rotation direction during the fixing operation), and FIG. 16B is a diagram illustrating the rotation of the fixing belt 101 in reverse (rotation in the reverse rotation mode). It is a figure which shows a mode made to (direction).
As shown in FIG. 16A, during the fixing operation, the heat transfer assisting member 116 receives a force from the pressure roller 103 via the fixing belt 101 in the downstream direction of the conveying direction. As a result, the heat transfer assisting member 116 moves together with the nip forming member 106 in the direction of the arrow E1 (downstream in the sheet conveying direction). Then, the positioning boss 106a of the nip forming member 106 hits the downstream end of the positioning hole 107c of the stay 107 in the transport direction, and the heat transfer assisting member 116 and the nip forming member 106 are brought closer to the downstream side in the transport direction.

  As shown in FIG. 16B, when the reverse rotation mode is executed to reversely rotate the pressure roller 103 and reversely rotate the fixing belt 101, the nip portion entrance side of the fixing belt 101 bends as described above. The nip exit side is stretched. By stretching the nip portion outlet side, the inner peripheral surface of the fixing belt 101 comes into contact with the nip outlet side of the heat transfer assisting member 116, and the lubricant staying at the nip outlet side is applied to the fixing belt 101 in the same manner as described above. Reattach.

  The heat transfer auxiliary member 116 receives a force from the pressure roller 103 via the fixing belt 101 in the upstream direction of the conveyance direction. As a result, the heat transfer assisting member 116 moves together with the nip forming member 106 in the direction of arrow E2 (downstream in the sheet conveying direction) in the figure. As described above, the length of the positioning hole 107c of the stay 107 in the sheet conveyance direction is 4.5 [mm], and the diameter of the positioning boss of the nip forming member 106 is 3 [mm]. Therefore, by changing from the normal rotation to the reverse rotation, the heat transfer auxiliary member 116 moves 1.5 [mm] upstream in the transport direction together with the nip forming member 106.

  The lubricant 301 staying on the inlet side of the nip portion is scraped off by the upstream end of the heat transfer auxiliary member 116 in the paper conveyance direction, and the scraped lubricant is applied to the nip forming surface of the heat transfer auxiliary member 116. It stays on the upstream end surface of the sheet conveying direction orthogonal to the upstream side. In the reverse rotation mode, the nip portion inlet side of the fixing belt bends. Therefore, in the reverse rotation mode, if the heat transfer auxiliary member 116 does not move upstream in the paper conveyance direction, the nip portion inlet side of the fixing belt is heated. Separated from the movement assisting member 116. Therefore, the lubricant 301 staying on the upstream end surface in the transport direction of the heat transfer auxiliary member 116 cannot be reattached to the fixing belt 101.

  However, in the present embodiment, in the reverse rotation mode, the heat transfer auxiliary member 116 moves 1.5 [mm] upstream in the conveyance direction together with the nip forming member 106. Accordingly, as shown in FIG. 16B, the lubricant 301 staying on the upstream end surface in the transport direction of the heat transfer auxiliary member 116 can be brought into contact with the fixing belt 101. Thereby, in the reverse rotation mode, the lubricant 301 staying on the upstream end surface in the transport direction of the heat transfer auxiliary member 116 can be reattached to the fixing belt. Thereby, by executing the reverse rotation mode, the staying lubricant on both the inlet side and the outlet side of the nip can be reattached to the fixing belt 101, and the sliding between the heat transfer assisting member 116 and the fixing belt 101 can be performed. An increase in resistance can be suppressed. Further, compared to the case where a mode in which the staying lubricant at the nip portion entrance side is reattached to the fixing belt 101 and a mode in which the staying lubricant at the nip portion exit side is reattached to the fixing belt 101 are executed. Downtime can be reduced.

  Further, in this embodiment, the staying lubricant 301 can be reattached to the inner peripheral surface of the fixing belt without causing torsional damage of the fixing belt due to slippage of the fixing belt 101, and the fixing belt 101 is kinked and damaged. It can be prevented from occurring.

  Next, a modification of this embodiment will be described.

[Modification 1]
FIG. 17 is a view illustrating the periphery of the nip portion of the fixing device according to the first modification.
In the fixing device of Modification 1, the shape on the nip exit side of the heat transfer assisting member 116 gradually protrudes toward the pressure roller 103 as it goes downstream in the sheet conveyance direction.

  In the first modification, the fixing belt 101 on the nip portion outlet side is bent in the same manner as described above, and is separated from the heat transfer assisting member 116, and then contacts the protruding shape portion 116a of the heat transfer assisting member 116. As described above, by providing the protruding shape portion 116a that protrudes toward the pressure roller from the nip portion N, the position at which the fixing belt 101 separated from the heat transfer assisting member 116 contacts the heat transfer assisting member 116 again is changed. 8 and 9, the shape of the nip portion outlet side of the heat transfer assisting member 116 can be made closer to the nip portion side than the flat shape. Thereby, the lubricant scraped off at the time of re-contact with the heat transfer assisting member 116 can stay on the nip portion side as compared with the configuration shown in FIGS.

  The following effects can be obtained by retaining the lubricant on the side of the nip portion. That is, the gap between the heat transfer assisting member 116 and the pressure roller 103 becomes narrower as it approaches the nip portion. For this reason, when the fixing belt 101 is rotated in the reverse direction and the exit side of the nip portion is set as the tension side, the fixing belt 101 is closer to the nip portion side where the gap between the heat transfer assisting member 116 and the pressure roller 103 is narrower. It becomes easy to contact the inner peripheral surface of the heat transfer auxiliary member 116. Therefore, by retaining the lubricant on the side in the nip portion, the lubricant retained on the heat transfer assisting member 116 is likely to adhere, and the retained lubricant can be adhered to the fixing belt 101 more reliably.

  Further, the shape of the heat transfer assisting member 116 on the nip exit side gradually protrudes toward the pressure roller 103 as it goes downstream in the sheet conveyance direction, and has the following advantages. That is, when the fixing belt is rotated in the reverse direction and the nip portion exit side of the fixing belt is stretched, no gap is generated between the fixing belt and the heat transfer assisting member 116. Thereby, it is an advantage that the lubricant staying on the exit side of the nip portion can be favorably reattached to the fixing belt.

What was demonstrated above is an example, and there exists an effect peculiar for every following aspect.
(Aspect 1)
A pressure member such as the pressure roller 103 is added to the contact member such as the heat transfer auxiliary member 116 that contacts the inner peripheral surface of the fixing member such as the endless fixing belt 101 with the lubricant 301 interposed therebetween. A fixing device that forms a nip portion N by pressing, rotates the pressure member to rotate the fixing member, passes a recording material such as paper P through the nip portion, and fixes the image on the recording material. At 100, a reverse rotation mode is executed in which the fixing member is rotated in a direction opposite to the rotation direction when the image is fixed on the recording material at a predetermined timing.
As a result of intensive research on the fixing device described in Patent Document 1, the present applicant has found that the lubricant of the sliding portion of the contact member such as the heat transfer auxiliary member 116 and the fixing member such as the fixing belt 101 for the following reason. It was found that depletion could not be suppressed sufficiently. That is, the fixing member has a substantially circular shape when not pressed against the contact member by a pressure member such as the pressure roller 103, and the inner peripheral surface of the fixing member is opposite to both ends of the contact member in the recording material conveyance direction. Only touching. When the fixing member is pressed against the contact member by the pressure member to form the nip portion, the contact member is brought into contact with the contact member so that the portion pressed by the pressure member is recessed, and the fixing member changes from a substantially circular shape to a substantially heart shape. Become. At this time, the fixing member contacts the contact member only at both ends of the contact member in the recording material conveyance direction and at the nip portion, and the inlet side and the outlet side of the nip portion are separated from the contact member. When the pressure member is driven to rotate from the substantially heart-shaped state and the fixing member is rotated, the fixing member drawn into the nip portion by the pressure member is shown in FIG. Thus, since the fixing member is pulled to the nip portion, it comes into contact with the contact member. On the other hand, the exit side of the nip portion where the fixing member is fed out from the nip portion is not separated from the contact member as before because the pulling force does not work as described above, and only at the downstream end of the contact member in the recording material conveyance direction. It looks like it is touching. As a result, on the exit side of the nip portion, the fixing member moves on the surface while sliding with the downstream end portion of the contact member in the recording material conveyance direction. When the contact member slides with the downstream end in the recording material conveyance direction, the lubricant adhering to the inner peripheral surface of the fixing member is scraped off, and the scraped lubricant 301 is fixed on the above-described nip portion outlet side. It has been found that the member stays in the gap between the fixing member formed apart from the contact member and the contact member.
In the lubricant movement mode described in Patent Document 1, in order to reduce the pressing force of the pressure member, the gap acts between the contact member on the nip outlet side and the inner peripheral surface of the fixing member. Further, in the lubricant movement mode described in Patent Document 1, the fixing belt is rotated in the same direction as when the image is fixed on the recording material. Thus, the lubricant staying on the surface does not adhere to the fixing belt and move. As a result, the lubricant staying on the nip exit side increases over time, and eventually the lubricant in the sliding portion between the contact member and the inner peripheral surface of the fixing belt is exhausted.
Therefore, in aspect 1, at a predetermined timing, the reverse rotation mode in which the fixing member is rotated in the direction opposite to the rotation direction when the image is fixed on the recording material is executed. By rotating in the reverse direction, the exit side of the nip portion becomes the side where the fixing member is drawn into the nip portion by the pressure member, and as shown in FIG. 11, the fixing member is not bent and contacts the contact member. . As a result, the lubricant staying on the downstream side in the recording material conveyance direction from the nip portion of the contact member can be adhered to the inner peripheral surface of the fixing member. Thereby, the lubricant staying on the nip portion outlet side can be moved to the sliding portion between the contact member and the inner peripheral surface of the fixing member.

(Aspect 2)
In the aspect 1, the downstream side in the recording material moving direction from the nip portion N of the contact member such as the heat transfer auxiliary member 116 is protruded toward the pressure member such as the pressure roller 103 from the nip portion.
According to this, as described in the first modification, the lubricant 301 can be retained at a position closer to the nip portion on the nip portion outlet side than in the case where the nip portion is not protruded. As a result, when the fixing member such as the fixing belt 101 is reversely rotated, the staying lubricant on the nip portion outlet side can be favorably adhered to the fixing belt 101.

(Aspect 3)
In Aspect 1 or Aspect 2, the reverse rotation mode is executed according to the cumulative number of printed sheets.
According to this, as described in the embodiment, the lubricant that stays increases as the cumulative number of printed sheets increases. Therefore, by executing the reverse rotation mode in accordance with the cumulative number of printed sheets, the appropriate timing can be obtained. The retained lubricant can be reattached to a fixing member such as the fixing belt 101.

(Aspect 4)
In Aspect 1 or Aspect 2, the reverse rotation mode is executed according to the cumulative number of rotations of the pressure member such as the pressure roller 103.
According to this, as described in the embodiment, the lubricant that stays increases as the cumulative number of rotations of the pressure member such as the pressure roller 103 increases, so the reverse rotation mode is set according to the cumulative number of rotations. By executing, the retained lubricant can be reattached to a fixing member such as the fixing belt 101 at an appropriate timing.

(Aspect 5)
In any one of aspects 1 to 4, the reverse rotation mode is executed when the temperature of a fixing member such as the fixing belt 101 is equal to or higher than a specified temperature.
According to this, as the temperature of the lubricant increases, the viscosity decreases, and the lubricant is likely to adhere to the fixing belt 101. Therefore, by executing the reverse rotation mode when the temperature of the fixing member such as the fixing belt 101 is equal to or higher than the specified temperature, the staying lubricant can be favorably reattached to the fixing member.

(Aspect 6)
In any one of the first to fifth aspects, the contact member such as the heat transfer auxiliary member 116 is movable within a predetermined range in the moving direction of the recording material.
According to this, as described in the embodiment, when the reverse rotation mode is executed, the contact member such as the heat transfer assisting member 116 moves to the upstream side in the recording material moving direction, and the heat transfer assisting member 116 moves the recording material. The lubricant staying at the upstream end in the direction can be brought into contact with the inner peripheral surface of a fixing member such as a fixing belt. Thereby, in the reverse rotation mode, the lubricant staying at the nip portion outlet side and the lubricant staying at the nip portion entrance side can be reattached to the fixing member. Thereby, exhaustion of the lubricant at the sliding portion between the contact member and the fixing member can be further suppressed.

(Aspect 7)
In any one of the first to sixth aspects, when the fixing member such as the fixing belt 101 is rotated once, the reverse rotation mode is ended.
According to this, as described in the embodiment, the lubricant 301 staying on the exit side of the nip portion can be attached to the entire circumference of the fixing member such as the fixing belt.

(Aspect 8)
In any one of the first to seventh aspects, the lubricant 301 is applied to the inner peripheral surface of a fixing member such as the fixing belt 101.
Thereby, the contact member such as the heat transfer assisting member 116 can be brought into contact with the inner peripheral surface of the fixing member such as the fixing belt with the lubricant 301 interposed therebetween.

(Aspect 9)
An image carrier such as the photosensitive drum 20, toner image forming means (in this embodiment, constituted by the charging device 30, the optical writing device 8, and the developing device 40) for forming a toner image on the image carrier, and the toner Transfer means such as a transfer device 71 for transferring an image from the image carrier onto a recording material, and fixing means such as a fixing device 100 for fixing the toner image transferred on the recording material to the recording material. In the image forming apparatus, the fixing device according to any one of aspects 1 to 6 is used as the fixing unit.
According to this, a good image can be obtained over time.

20: photosensitive drum 30: charging device 40: developing device 71: transfer device 90: control unit 91: thermistor 100: fixing device 101: fixing belt 102: halogen heater 103: pressure roller 104: elastic rubber layer 105: cored bar 106: Nip forming member 106a: Positioning boss 107: Stay 107c: Positioning hole 109: Reflecting member 116: Heat transfer auxiliary member 116a: Protruding shape portion 126: End heater 126 End heater 203: Pressure roller drive motor 301: Lubrication Agent N: Nip part P: Paper

Japanese Patent No. 5511252

Claims (9)

A pressure member is pressed through the fixing member to a contact member that contacts an inner circumferential surface of the endless fixing member with a lubricant interposed therebetween, and a nip portion is formed, and the pressure member is driven to rotate. In the fixing device that rotates the fixing member and passes the recording material through the nip portion to fix the image on the recording material.
A fixing device that executes a reverse rotation mode in which the fixing member is rotated in a direction opposite to a rotation direction when the image is fixed on a recording material at a predetermined timing. The fixing device according to claim 1,
A fixing device characterized in that the downstream side of the contact member in the recording material moving direction from the nip portion protrudes from the nip portion to the pressure member side. The fixing device according to claim 1 or 2,
A fixing device that executes the reverse rotation mode in accordance with a cumulative number of printed sheets. The fixing device according to claim 1 or 2,
The fixing device, wherein the reverse rotation mode is executed according to a cumulative number of rotations of the pressure member. The fixing device according to claim 1,
The fixing device according to claim 1, wherein the reverse rotation mode is executed when a temperature of the fixing member is equal to or higher than a specified temperature. 6. The fixing device according to claim 1, wherein the contact member is movable within a predetermined range in a moving direction of the recording material. The fixing device according to claim 1,
The fixing device is characterized in that the reverse rotation mode is terminated when the fixing member is rotated once. The fixing device according to claim 1, wherein the lubricant is applied to an inner peripheral surface of the fixing member. An image carrier, a toner image forming unit for forming a toner image on the image carrier, a transfer unit for transferring the toner image from the image carrier to a recording material, and a toner transferred on the recording material In an image forming apparatus comprising fixing means for fixing an image to the recording material,
An image forming apparatus using the fixing device according to claim 1 as the fixing unit.

Images