JP5838615B2 - Fixing device and image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having the functions thereof, and a fixing device mounted on the image forming apparatus.

A belt-type fixing device is used as a fixing device that fixes a toner image transferred onto transfer paper (also referred to as recording paper) by an image forming apparatus using an electrophotographic method.
A belt-type fixing device includes a rotatable fixing belt having a heating source, a pressure roller that is pressed against and rotates on the fixing belt, and an inner side of the fixing belt. And a pressing member that forms a nip portion between the fixing belt and the pressure roller by pressing toward the fixing belt. By passing the transfer paper through the nip portion, the unfixed toner image on the transfer paper is heated and pressed and fixed. What you do is known.

  In addition, a rotatable fixing roller having a heating source, a pressure belt rotating in pressure contact with the fixing roller, and disposed inside the pressure belt, the pressure belt is pressed toward the fixing roller. A pressing member for forming a nip portion between the pressure belt and the fixing roller, and passing the transfer paper through the nip portion so that the unfixed toner image on the transfer paper is heated and pressed and fixed. What was done is also known.

  In these belt-type fixing devices, if the friction coefficient between the endless belt and the pressing member is large, the torque for driving the endless belt increases, and the drive acting on the fixing roller or the pressure roller for driving the endless belt. In some cases, the torque also increases, causing damage to the fixing roller or the pressure roller, or causing a load on the drive gear train to be damaged. In addition, the load on the drive motor is increased, the motor becomes larger, and more power is required. In addition, the wear of the inside of the endless belt and the sliding portion of the pressing member was severe, and the life of the parts was remarkably shortened. When the frictional force between the endless belt and the pressing member becomes so large that it cannot be ignored compared to the driving force of the endless belt by the fixing roller or pressure roller, slip occurs between the fixing roller or pressure roller and the endless belt, When the transfer paper holding the unfixed toner image under such conditions is passed through the nip, the transfer paper may be wrinkled or the image may be shifted in the unfixed toner image on the transfer paper.

  For this reason, the belt-type fixing device is required to have a small sliding resistance between the endless belt (fixing belt or pressure belt) and the pressing member disposed inside the endless belt. A sliding friction member is provided between them, and further, for example, oil or grease is applied between the inner side of the endless belt and the pressing member to reduce the sliding resistance between them (Patent Documents 1 to 3). 3). FIG. 7 shows a schematic configuration of a fixing device in which a rubbing member is fixed between the endless belt inside and the pressing member.

  A fixing belt 92 is disposed on the toner image T carrying surface side of the transfer paper P, and a pressure roller 91 is disposed on the back surface side of the transfer paper P so as to face the fixing belt 92. The pressure roller 91 is rotated by a drive motor (not shown), and the fixing belt 92 is driven to rotate.

  In the inner peripheral region of the fixing belt 92, a halogen heater 84 is disposed as an example of a heat source. A pressing member 83 held and fixed by the holding member 65 presses the pressure roller 91 via the fixing belt 92 to form a fixing nip portion N on the paper passing side of the halogen heater 84. Between the inner peripheral surface of the fixing belt 92 and the pressing member 83, a sliding member 68 having a low frictional resistance is provided between the fixing member belt 65 and the holding member 65 in order to reduce the sliding resistance between the inner peripheral surface of the belt and the pressing member 83. The upstream side of the rotation is fixed and arranged.

  The pressure roller 91 is configured by laminating a cored bar 911, a heat-resistant elastic body layer 912 coated on the outer peripheral surface of the cored bar 911, and a release layer 913 formed of a heat-resistant resin coating or a heat-resistant rubber coating. ing. On the other hand, the fixing belt 92 is an endless belt whose original shape is formed in a cylindrical shape, and is formed of a heat-resistant resin such as polyimide, polyamide, or polyimideamide, or a metal such as SUS or nickel, as partially shown in FIG. The base layer 921 and a release layer 922 made of a fluororesin or the like coated on the surface or both surfaces of the base layer 921 on the pressure roller 91 side. In some cases, a heat-resistant elastic layer 923 is provided between the base layer 921 and the release layer 922 (outermost layer). A heat absorption rate adjustment layer 924 is provided on the innermost peripheral surface. Incidentally, the film strength of the heat absorption rate adjusting layer 924 is set larger than the surface strength of the pressing member 83. The surface strength can be expressed as wear amount, wear depth, pencil hardness, Vickers hardness, and scratch strength.

  However, the method of fixing and providing a low-friction rubbing member between the inner side of the endless belt and the pressing member can initially reduce the sliding resistance of both, but has sufficient durability over time. It can not be said.

  On the other hand, a non-glossy black coating is often applied to the inner side of the endless belt in order to improve heat absorption from a heating source disposed inside the endless belt. Furthermore, a heat absorption rate adjusting layer for adjusting heat absorption to prevent excessive cooling and excessive heating may be provided (Patent Document 4). A heat absorption rate adjustment layer is a layer provided using the coating material whose heat absorption rate changes with temperature changes like a thermochromic ink, for example. This paint is black in the low temperature range and has a high heat absorption rate from the heat source. In the high temperature range, it changes to white, silver, or colorless, and the heat absorption rate is low. Then, by setting the relationship of “film strength of the innermost layer of the rotating body”> “surface strength of the pressing member”, the surface of the pressing member is first worn against the surface of the innermost layer of the rotating body, and the surface of the innermost layer of the rotating body is deteriorated. It has been done to prevent. However, with such a configuration, the life of the pressing member is significantly reduced.

  An object of the present invention is to provide a temporal change between the outer peripheral surface of a pressing member that presses the rotating member from the inside of one of two rotating members that form a fixing nip and the inner peripheral surface of the rotating member. It is intended to improve the durability of the pressing member and the rotating member while preventing a situation in which the sliding resistance increases.

According to the present invention, according to the present invention, at least one heating member is attached to at least one of the two rotating members that are in contact with each other, and one of the rotating members is disposed in an inner peripheral area, and the rotating member is pressed against the other rotating member. And a low friction friction member disposed on the outer peripheral surface of the pressing member, the rubbing member rubs against the inner peripheral surface of the rotating member on which the pressing member is disposed. The pressing member is an endless rotating body, the rubbing member is rotatable together with the pressing member, and the film strength of the innermost layer located on the inner peripheral surface of the rotating member provided with the pressing member is This can be solved by setting the surface strength higher than the surface strength of the rubbing member.

  By setting the film strength of the innermost layer of the rotating member provided with the pressing member to be larger than the surface strength of the rubbing member provided on the outer peripheral surface of the pressing member, deterioration of the rotating member or its innermost layer over time is prevented. By moving the rubbing member with the rotation of the pressing member, it is possible to suppress a situation in which the frictional resistance between the rotating member and the rubbing member increases, and to improve the durability of the rubbing member. Can be improved.

1 is a cross-sectional view of a printer equipped with an example of a fixing device according to the present invention. 1 is a schematic configuration diagram of a fixing device according to a first embodiment of the present invention. It is a figure which shows the structure of a press member, a holding member, and a rubbing member, a is a longitudinal direction side view, b is sectional drawing. It is a schematic block diagram of the fixing device which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of a press member, a holding member, and a rubbing member, a is a longitudinal direction side view, b is sectional drawing. It is a schematic block diagram of the fixing device which concerns on 3rd Embodiment of this invention. It is a schematic block diagram of the fixing device which concerns on a prior art. FIG. 3 is a partial view showing a laminated structure of a fixing belt.

An embodiment according to the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional configuration of a printer 1 in which an example of a fixing device according to the present invention is mounted. The overall configuration and operation of the printer 1 will be described later, and the fixing device will be described first.

  FIG. 2 shows a schematic configuration of the fixing device according to the first embodiment of the present invention. 7 shows the basic structure in which the main part is constituted by the fixing belt 92 and the pressure roller 91, and the halogen heater 84 as a heat source is arranged in the inner peripheral region of the fixing belt 92, and the structure and material of each member. Since it is the same as the fixing device according to the technology, for the sake of simplification of description, the configuration other than the configuration related to the present embodiment will be described with reference to FIGS. 7 and 8 in the background art section. In the apparatus shown in FIG. 2, the fixing member is an endless belt and the pressure member is a roller. However, as a belt-type fixing device, the fixing member is a roller and the pressure member is an endless belt (belt inner circumference). Needless to say, the present invention can be applied to a structure having a pressing member on the side.

  The pressing member 83 ′ that presses the pressure roller 91 via the fixing belt 92 to form the fixing nip portion N is fixed in the conventional example of FIG. 7, but in this embodiment, between the fixing belt 92 and the fixing belt 92. When the frictional resistance varies, the motor is rotated by a motor (not shown). As shown in FIG. 3, the holding member 65 ′ that holds the pressing member 83 ′ constitutes a rotation shaft, and the outer peripheral surface of the pressing member 83 ′ is covered with a rubbing member 68 having a low frictional resistance. It rotates with the member 83 ′. The rubbing member 68 is composed of a heat resistant resin nonwoven fabric, a heat resistant resin film, a liquid crystal polymer sheet, a liquid crystal polymer film, a porous resin fiber woven fabric, a porous resin film, a glass fiber sheet, and the like. Fluorine etc. are used. The rubbing member 68 may be impregnated with silicone oil, heat-resistant grease or the like as a lubricant. The surface strength of the rubbing member 68 is set to be smaller than the film strength of the heat absorption rate adjusting layer 924 provided on the innermost surface of the fixing belt 92. The surface strength can be expressed as wear amount, wear depth, pencil hardness, Vickers hardness, and scratch strength. The pressing member 83 'is made of a heat resistant elastic material such as a heat resistant resin or silicone rubber, and the holding member 65' is made of a metal material such as a heat resistant resin or SUS.

  Fluctuation resistance varies between the pressing member 83 ′ and the fixing belt 92, strictly speaking, between the rubbing member 68 on the outer periphery of the pressing member 83 ′ and the inner peripheral surface (heat absorption rate adjusting layer) of the fixing belt 92. Therefore, a detection member (not shown) for detecting the torque fluctuation of the fixing belt 92 or the torque fluctuation of the pressure roller 91 that rotates around the fixing belt 92 is provided, and a value equal to or higher than a preset torque value is provided. If detected, a control unit (not shown) instructs the pressing member 83 ′ to rotate, and the pressing member 83 ′ is rotated to rub against the heat absorption rate adjustment layer on the innermost surface of the fixing belt 92. The fresh portion of the rubbing member 68 that has not been moved is moved to a position for rubbing against the heat absorption rate adjusting layer. The movement is executed when it is detected that the fixing belt 92 or the pressure roller 91 is not rotating.

  Instead of the above-described configuration that actually detects the frictional resistance variation and recognizes the deterioration of the rubbing member over time, the pressure gradually increases as the fixing belt 92 or the pressure roller 91 rotates. The member 83 ′ is rotated to move the surface area of the rubbing member 68 that actually rubs against the heat absorption rate adjustment layer on the innermost surface of the fixing belt 92 so that the sliding resistance is always kept in a good state. Also good. Further, the number of rotations of the fixing belt 92 or the pressure roller 91 is counted or the rotation time is accumulated, and when a predetermined value is reached, the pressing member 83 ′ and the rubbing member 68 are rotated, The fresh portion of the rubbing member 68 is moved to a position where it rubs against the heat absorption rate adjusting layer, and the number of rotations of the fixing belt 92 or the pressure roller 91 is counted again from the movement, or the rotation time is accumulated, The pressing member 83 ′ and the rubbing member 68 may be rotated intermittently. By doing in this way, before the frictional resistance deteriorates with time, the frictional member 68 can be changed to an appropriate frictional resistance region. The movement in the case of counting the number of rotations and the accumulation of the rotation time is also executed after it is detected that the fixing belt 92 or the pressure roller 91 is not rotating, whereas the pressing member 83 ′ is gradually moved. This movement can be performed while the fixing belt 92 and the pressure roller 91 are rotating or while the fixing belt 92 and the pressure roller 91 are stopped. In any case, an adverse effect (unevenness of rotation or vibration) on the fixing belt is avoided by executing the movement at a timing when the sheet is not passed through the fixing nip portion.

  FIG. 4 shows a schematic configuration of a fixing device according to another embodiment. 7 and 2 also show the basic structure in which the main part is constituted by the fixing belt 92 and the pressure roller 91 and the halogen heater 84 as a heat source is arranged in the inner peripheral area of the fixing belt 92, and the structure and material of each member. Since it is the same as the fixing device shown, only the configuration related to the present embodiment will be described for the sake of simplification of description. In the apparatus shown in FIG. 4, the fixing member is an endless belt and the pressure member is a roller. However, as a belt type fixing device, the fixing member is a roller and the pressure member is an endless belt (belt inner circumference). It is the same as that of the example of FIG. 2 that the present invention can be applied to the configuration that is a pressing member on the side. The surface strength of the rubbing member 68 is set to be smaller than the film strength of the heat absorption rate adjustment layer 924 provided on the innermost surface of the fixing belt 92 as in the example of FIG.

  In the example of FIG. 2, the cross-sectional shape of the pressing member 83 ′ is circular. However, in the configuration of FIG. 4, the cross-sectional shape of the pressing member 83 ″ is a polygon (hexagon). A pressing member 83 ″ that presses 91 to form the fixing nip portion N is also rotated by a motor (not shown) when there is a change in frictional resistance with the fixing belt 92. Since the cross-sectional shape of the pressing member 83 ″ is polygonal, it is relatively easy to ensure a nip length longer than that required for fixing regardless of the material of the pressing member 83 ″ and the pressure roller 91. As shown in FIG. 5, the holding member 65 ′ holding the pressing member 83 ″ constitutes a rotating shaft, and the outer peripheral surface of the pressing member 83 ″ is covered with a rubbing member 68 having a low frictional resistance. It rotates together with the member 83 ″. The materials of the rubbing member 68, the pressing member 83 ″, and the holding member 65 ′ are the same as in the example of FIG.

  The torque fluctuation of the fixing belt 92 due to the fluctuation of the frictional resistance between the rubbing member 68 on the outer periphery of the pressing member 83 ″ and the inner peripheral surface (heat absorption rate adjusting layer) of the fixing belt 92, or the fixing belt 92 A detection member (not shown) for detecting torque fluctuation of the rotating pressure roller 91 is provided, and when a value equal to or higher than a preset torque value is detected, a pressing member is pressed from a control unit (not shown). When an instruction is given to the 83 "rotating motor, the pressing member 83" is rotated to absorb the fresh surface of the rubbing member 68 that did not rub against the heat absorption rate adjusting layer on the innermost surface of the fixing belt 92. The position is moved to a position for rubbing against the rate adjusting layer, and the movement is executed when it is detected that the fixing belt 92 or the pressure roller 91 is not rotating.

  Instead of detecting the change in frictional resistance and recognizing the deterioration of the rubbing member over time, the rotation speed of the fixing belt 92 or the pressure roller 91 is counted or the rotation time is changed. When the accumulated value reaches a predetermined value, the pressing member 83 ″ and the rubbing member 68 are rotated, and the fresh surface of the rubbing member 68 is moved to a position for rubbing with the heat absorption rate adjusting layer. From this movement, the number of rotations of the fixing belt 92 or the pressure roller 91 may be counted again, or the rotation time may be accumulated to intermittently rotate the pressing member 83 ″ and the rubbing member 68. By doing in this way, before the frictional resistance deteriorates with time, the frictional member 68 can be changed to an appropriate frictional resistance region. Movement in the case of rotation count and rotation time integration is also executed after it is detected that the fixing belt 92 or the pressure roller 91 is not rotating. By executing the movement during such non-rotation, adverse effects (unevenness of rotation and vibration) on the fixing belt are avoided.

  FIG. 6 shows a schematic configuration of a fixing device according to still another embodiment. The fixing belt 92 and the pressure roller 91 constitute the main part, and the basic structure in which the halogen heater 84 as a heat source is arranged in the inner peripheral area of the fixing belt 92 and the structure and material of each member are also shown in FIGS. Since this is the same as the fixing device shown in FIG. 4, only the configuration related to the present embodiment will be described for the sake of simplicity. In the apparatus shown in FIG. 6, the fixing member is an endless belt and the pressure member is a roller. However, as a belt-type fixing device, the fixing member is a roller and the pressure member is an endless belt (belt inner circumference). It is the same as in the example of FIG. 2 and FIG. 4 that the present invention can be applied to the configuration that is a pressing member on the side. The surface strength of the rubbing member 68 is set to be smaller than the film strength of the heat absorption rate adjustment layer 924 provided on the innermost surface of the fixing belt 92, which is the same as the example of FIGS. .

  In the configuration of FIG. 6, an endless belt-shaped pressing member 83 ′ ″ formed of a heat-resistant resin such as polyimide, polyamide, and polyimideamide, a metal such as SUS and nickel, and a heat-resistant elastic material such as silicone rubber has a cross-section. The holding member 65 ″ is held by a rectangular holding member 65 ″ and is tensioned by the tension roller 70. The holding member 65 ″ is fixed by the lower side regardless of the material of the pressing member 83 ′ ″ and the pressure roller 91. It is relatively easy to ensure a nip length longer than required. A pressing member 83 ′ ″ whose outer peripheral surface is covered with a rubbing member 68 having a low frictional resistance is rotated by a motor (not shown) when the frictional resistance varies with the fixing belt 92. As a result, the contact portion of the rubbing member 68 with the inner peripheral surface of the fixing belt 92 also moves.

  The torque fluctuation of the fixing belt 92 due to the fluctuation of the frictional resistance between the rubbing member 68 on the outer periphery of the pressing member 83 '' 'and the inner peripheral surface (heat absorption rate adjusting layer) of the fixing belt 92, or the fixing belt A detection member (not shown) for detecting the torque fluctuation of the pressure roller 91 that rotates around 92 is provided, and when a value greater than a preset torque value is detected, a control unit (not shown) The pressing member 83 ′ ″ is instructed to rotate, and the pressing member 83 ′ ″ is rotated so that the rubbing member 68 that did not rub against the heat absorption rate adjusting layer on the innermost surface of the fixing belt 92 is obtained. The fresh portion is moved to a position where it rubs against the heat absorption rate adjusting layer. The movement is executed when it is detected that the fixing belt 92 or the pressure roller 91 is not rotating.

  Instead of the above-described configuration that actually detects the frictional resistance variation and recognizes the deterioration of the rubbing member over time, the pressure gradually increases as the fixing belt 92 or the pressure roller 91 rotates. The member 83 ′ ″ is rotated to move the surface area of the rubbing member 68 that actually rubs with the heat absorption rate adjustment layer on the innermost surface of the fixing belt 92 so that the sliding resistance is always kept in a good state. It may be. Further, the number of rotations of the fixing belt 92 or the pressure roller 91 is counted, or the rotation time is integrated, and when the predetermined value is reached, the pressing member 83 ′ ″ and the rubbing member 68 are rotated. Then, the fresh portion of the rubbing member 68 is moved to a position where it rubs against the heat absorption rate adjusting layer, and the number of rotations of the fixing belt 92 or the pressure roller 91 is counted again from that movement, or the rotation time is integrated. Thus, the pressing member 83 ′ ″ and the rubbing member 68 may be rotated intermittently. By doing in this way, before the frictional resistance deteriorates with time, the frictional member 68 can be changed to an appropriate frictional resistance region. While the movement in the case of counting the number of rotations or integrating the rotation time is also performed after detecting that the fixing belt 92 or the pressure roller 91 is not rotating, the pressing member 83 ′ ″. The gradual movement can be executed even when the fixing belt 92 and the pressure roller 91 are rotating or while the fixing belt 92 and the pressure roller 91 are stopped. In any case, an adverse effect (unevenness of rotation or vibration) on the fixing belt is avoided by executing the movement at a timing when the sheet is not passed through the fixing nip portion.

  Finally, the schematic configuration and operation of the printer 1 shown in FIG. 1 will be briefly described. Incidentally, the mechanism of the entire printer is basically the same as the conventional mechanism, and even if it is not described in the following description, those skilled in the art can immediately understand the basic configuration and operation.

  The printer 1 is a color laser printer, and has a configuration in which a paper feeding unit 2 is provided at a lower portion of the apparatus main body, and an image forming unit 3 is disposed above the paper feeding unit 2. A paper discharge tray 40 is formed on the upper surface of the apparatus. As shown by the broken line in the drawing, the recording paper is transported from the paper supply unit 2, and the image formed by the image forming unit 3 is transferred onto the transfer paper and fixed by the fixing device 90. Paper is discharged to the paper discharge tray 40. Note that manual sheet feeding (symbol: h) is possible from the side of the apparatus. In addition, a double-sided device is mounted on the left side of the apparatus main body in the drawing, and after fixing, the transfer paper can be reversed and fed again via the double-sided conveyance unit 30. Further, the transfer paper can be discharged from the double-sided device to a paper discharge tray (not shown) in the side surface direction of the device.

  The image forming unit 3 is provided with a transfer / conveying belt device 20 that is disposed so as to be inclined so that the paper feeding side is on the bottom and the paper discharge side is on the top. Four image forming units 4M, 4C, 4Y, and 4Bk for magenta (M), cyan (C), yellow (Y), and black (Bk) in order from the bottom along the upper traveling side of the transfer conveyance belt device 20. Are arranged side by side. Since the image forming units 4M, 4C, 4Y, and 4Bk have the same configuration, the alphabet (M, C, Y, Bk) indicating each color will be omitted here. Each image forming unit 4 includes a photosensitive drum 5 as an image carrier, and the photosensitive drum 5 is rotationally driven in a clockwise direction in the drawing by a driving unit (not shown). Around the photosensitive drum 5, a charging roll, a developing device, a cleaning device, and the like are provided. Laser light from the optical writing device 8 is applied to the photosensitive drum 5 from between the charging roll and the developing device.

  The endless loop-shaped transfer / conveying belt 21 is wound around a driving roller 22, a driven roller 23, and two tension rollers 24 and 24. The transfer brush 28 is disposed on the inner side of the upper running side of the transfer conveyance belt 21 at a position facing the photosensitive drum 5 of each color image forming unit so as to contact the belt 21. A paper suction roller 27 is provided above the driven roller 23 with the belt 21 interposed therebetween. The recording paper is fed onto the belt 21 from between the driven roller 23 and the suction roller 27, and is transported while being electrostatically attracted onto the transfer transport belt 21 by the bias voltage applied to the suction roller 27. The transfer / conveyance belt device 20 is held by a mechanism (not shown) so that the belt 21 is in contact with the four-color image forming units 4M, 4C, 4Y, and 4Bk (photosensitive drums) in the case of color printing. In the case of printing, the state in which the belt 21 is in contact with only the image forming unit 4Bk (the photosensitive drum) is maintained.

  Next, the printing operation will be described. In the image forming unit 4M for magenta, the surface of the photosensitive drum 5 is uniformly charged to a predetermined potential by a charging roll. In the exposure apparatus 8, an LD (laser diode) (not shown) is driven based on image data sent from a host machine such as a personal computer to irradiate the polygon mirror 7 with laser light, and reflected light via a cylinder lens or the like. Is guided onto the photosensitive drum 5M, and an electrostatic latent image to be developed with magenta toner is formed on the photosensitive drum 5M. Toner is applied to the latent image from the developing device, and a visible image of magenta toner is formed. On the other hand, a recording paper of a predetermined size designated as a transfer material is fed from the paper feeding unit 2, and the fed recording paper is fed to a registration roller pair 40 provided on the upstream side in the conveyance direction of the transfer conveyance belt device 20. Once hit. At the time of color printing, in the transfer / conveying belt device 20, the transfer / conveying belt 21 is pushed up as described above, and the belt 21 is in contact with the four-color image forming units 4M, 4C, 4Y, and 4Bk (photosensitive drums thereof). . Then, the recording paper is fed onto the belt 21 in synchronism with the visible image, and reaches the transfer position facing the photosensitive drum 5M as the belt runs. At this transfer position, a visible image of magenta toner is transferred onto the transfer paper by the action of the transfer brush 28 disposed on the back side of the transfer belt 20. Similarly to the case of the magenta color, in the other image forming units 4C, 4Y, and 4Bk, visible images are formed by the respective toners on the surfaces of the respective photosensitive drums 5, and these visible images are transferred by the transfer conveyance belt 21. Each time the transferred transfer paper arrives at each transfer position, the transfer is overlaid. Therefore, in the color printer of this embodiment, a full-color image is transferred onto the transfer paper in a short time that is almost the same as that of monochrome.

  On the other hand, in the case of monochrome printing, in the transfer / conveyance belt device 20, the transfer / conveyance belt 21 is lowered as described above, and the belt 21 is in contact with only the image forming unit 4Bk (the photosensitive drum). Only in the black image forming unit 4Bk, a visible image of black toner is formed on the surface of the photosensitive drum 5, and the recording paper fed on the belt 21 so as to be synchronized with the visible image of Bk. In contrast, a Bk toner image is transferred.

  The transfer paper after the transfer of the toner image is separated from the transfer conveyance belt 21 and fixed by the fixing device 90. After the fixing, the transfer paper is discharged to a paper discharge tray 40 provided on the upper surface of the apparatus main body or is transferred to a double-sided apparatus.

65, 65 ′, 65 ″ holding member 68 rubbing member 83, 83 ′, 83 ″, 83 ′ ″ pressing member 84 halogen heater 91 fixing belt 92 pressure roller

JP 2001-228731 A JP 2004-258484 A JP 2005-266716 A Japanese Patent Laid-Open No. 10-282823

Claims (8)

Two rotating members attached to at least one of the heating members and in contact with each other;
A pressing member that is arranged in one inner peripheral area of these rotating members and presses the rotating member against the other rotating member;
In the fixing device having a low friction sliding member disposed on the outer peripheral surface of the pressing member,
The rubbing member rubs against the inner peripheral surface of the rotating member on which the pressing member is disposed;
The pressing member is an endless rotating body;
The rubbing member is rotatable together with the pressing member;
A fixing device, wherein a film strength of an innermost layer located on an inner peripheral surface of a rotating member provided with the pressing member is larger than a surface strength of the rubbing member.   The fixing device according to claim 1, wherein the pressing member rotates as the rotation time of the rotating member elapses.   The fixing device according to claim 1, wherein the pressing member rotates every predetermined rotation time of the rotating member.   The fixing device according to claim 1, wherein the pressing member is rotated when the rotating member is not rotating.   The fixing device according to claim 1, wherein the rotation of the pressing member is performed after a predetermined rotation time of the rotating member and when the rotating member is not rotating. .   The fixing device according to claim 1, wherein an axial cross-sectional shape of the pressing member is a polyhedron.   The pressing member is held by a holding member disposed in the inner peripheral area of the pressing member,
  The fixing device according to claim 1, wherein the holding member has a rectangular cross-sectional shape in the longitudinal direction. An image forming apparatus having a fixing device according to any one of claims 1-7.

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