JP2019184704A - Fixing device and image forming apparatus - Google Patents

Abstract

To prevent at least one of damage to a pressure roller due to excessive compression and leakage of electricity from a planar heater to the shaft of the pressure roller.SOLUTION: A fixing device 9 comprises: a pair of transmission members 30 that are arranged opposite on both ends of a fixing belt 21, and transmit a load for pressing a planar heater 23 against the fixing belt 21 to a heater holding member 25 to form a pressure area in which a sheet is held and conveyed between the fixing belt 21 and a pressure roller 27; and holding members 40 that hold the transmission members 30, permit sliding of the transmission members 30 in the radial direction of the pressure roller 27, and include contact parts 46 that, when the distance between the planar heater 23 and a shaft 271 of the pressure roller 27 reaches a predetermined minimum value, each come into contact with a portion opposite to the transmission member 30 or the shaft 271 of the heater holding member 25.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a fixing device that fixes a toner image on a sheet and an image forming apparatus including the fixing device.

  As one heating method of the fixing device, a method of heating only the nip portion using a heating body (planar heater) in which a resistance heating element is formed on a ceramic substrate is known. This method is excellent in energy saving because it has a high temperature rise and heats only the necessary part. However, in this method, when the heating area of the heating body is removed from the nip portion, the heating body itself may be exposed to a high temperature and damaged.

  Therefore, conventionally, a technique for improving the positioning accuracy of the heating body has been studied. For example, in the fixing device described in Patent Document 1, the pressure roller is positioned on the pressure roller support member via the bearing, and the pressure transmission member is positioned by being fitted to the pressure roller support member. . The pressure transmission member presses the heating body (planar heater) to the pressure roller via the heating body holding member by transmitting the pressure of the spring.

Japanese Patent Laid-Open No. 2002-268412

  However, in the fixing device described in Patent Document 1, since there is no restriction on the movement of the pressure transmission member in the pressure direction, the pressure roller is compressed more than necessary due to component tolerances such as a spring and a pressure roller. There is a fear. Since the range of the compression rate that can be used for the pressure roller is determined, if the pressure roller continues to be used at a compression rate exceeding that range, it will be damaged. Further, in the fixing device described in Patent Document 1, the planar heater is disposed at a position facing the pressure roller. However, since the hardness of the pressure roller decreases as time passes, The distance from the shaft of the pressure roller is shortened. If this distance is less than the limit, electric leakage from the planar heater to the shaft of the pressure roller may occur, which may damage the device.

  In consideration of the above circumstances, the present invention provides a fixing device and an image forming apparatus capable of preventing at least one of breakage of the pressure roller due to excessive compression and electric leakage from the planar heater to the shaft of the pressure roller. The purpose is to provide.

  In order to solve the above-described problems, a fixing device according to the present invention includes a cylindrical fixing belt, a planar heater for heating the fixing belt, and the planar heater in contact with an inner peripheral surface of the fixing belt. A heater holding member to be held, a pressure roller for sandwiching the fixing belt between the planar heater, and an opposite end of the fixing belt are disposed so as to press the planar heater against the fixing belt. A pair of transmission members that form a pressure region in which a sheet is nipped and conveyed between the fixing belt and the pressure roller, and the transmission member is held by transmitting a load to the heater holding member And allowing the transmission member to slide in the radial direction of the pressure roller, and when the distance between the planar heater and the axis of the pressure roller reaches a predetermined minimum value, Serial and transmitting member or a pair of holding members having a contact portion that contacts the portion facing the axis of the pressure roller of the heater holding member, characterized in that it comprises a.

  In the fixing device according to the present invention, the minimum value is a minimum distance at which the pressure roller is not damaged by compression, and a minimum distance at which no leakage occurs from the planar heater to the axis of the pressure roller. It may be characterized in that the value is greater than the larger one of the values.

  In the fixing device according to the present invention, the minimum value may be a value equal to or greater than a minimum value of a distance at which the pressure roller is not damaged by compression.

  In the fixing device according to the present invention, the minimum value may be a value equal to or greater than a minimum value of a distance at which no leakage occurs from the planar heater to the shaft of the pressure roller.

  In the fixing device according to the present invention, the transmission member includes a sliding convex portion formed to extend in a sliding direction, and the holding member includes a sliding concave portion corresponding to the sliding convex portion, The contact portion may be formed at an end portion of the sliding concave portion on the pressure roller side, and may be in contact with an end portion of the sliding convex portion on the pressure roller side.

  In the fixing device according to the present invention, the holding member may be formed of an insulator, and a part of the holding member may be located between the shaft of the pressure roller and the planar heater.

  An image forming apparatus according to the present invention includes: an image forming unit that forms a toner image on the paper; and the fixing device according to claim 1 that fixes the toner image on the paper. It is characterized by providing.

  According to the present invention, it is possible to prevent at least one of breakage of the pressure roller due to excessive compression and electric leakage from the planar heater to the shaft of the pressure roller.

1 is a front view schematically showing an internal configuration of a printer according to an embodiment of the present invention. 1 is a cross-sectional view of a fixing device according to an embodiment of the present invention. It is a side view of the transmission member concerning one embodiment of the present invention. 1 is a side view of a fixing device equipped with a transmission member according to an embodiment of the present invention. It is a perspective view of the transmission member concerning one embodiment of the present invention. It is a perspective view of the holding member concerning one embodiment of the present invention. It is sectional drawing of the holding member which concerns on one Embodiment of this invention. It is a perspective view of the pressure roller support member concerning one embodiment of the present invention. FIG. 6 is a perspective view illustrating an assembling procedure of the fixing device according to the embodiment of the present invention. FIG. 6 is a perspective view illustrating an assembling procedure of the fixing device according to the embodiment of the present invention. FIG. 6 is a perspective view illustrating an assembling procedure of the fixing device according to the embodiment of the present invention. FIG. 6 is a perspective view illustrating an assembling procedure of the fixing device according to the embodiment of the present invention. It is sectional drawing of the holding member and transmission member which concern on one Embodiment of this invention.

  Hereinafter, an image forming apparatus and a fixing device of the present invention will be described with reference to the drawings.

  First, an overall configuration of a printer 1 as an image forming apparatus will be described with reference to FIG. FIG. 1 is a front view schematically showing the internal configuration of the printer 1. Hereinafter, the front side of the paper in FIG. 1 is the front side (front side) of the printer 1, and the left and right directions will be described with reference to the direction when the printer 1 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr indicate up, down, left, right, front, and back, respectively.

  The apparatus main body 2 of the printer 1 includes a paper feed cassette 3 that accommodates the paper S, a paper feed device 5 that feeds the paper S from the paper feed cassette 3, an image forming unit 7 that forms a toner image on the paper S, A fixing device 9 that fixes the toner image onto the paper S, a paper discharge device 11 that discharges the paper S, and a paper discharge tray 13 that receives the discharged paper S are provided. Further, a conveyance path 15 for the sheet S from the sheet feeding device 5 to the sheet discharge device 11 through the image forming unit 7 and the fixing device 9 is formed in the apparatus main body 2.

  The paper S fed from the paper feed cassette 3 by the paper feeding device 5 is transported to the image forming unit 7 along the transport path 15, and a full-color toner image is formed on the paper S. The sheet S is sent to the fixing device 9 along the conveyance path 15 and the toner image is fixed on the sheet S. The paper S on which the toner image is fixed is discharged from the paper discharge device 11 to the paper discharge tray 13.

  Next, the configuration of the fixing device 9 will be described with reference to FIG. FIG. 2 is a cross-sectional view of the fixing device 9. The fixing device 9 includes a cylindrical fixing belt 21, a planar heater 23 that heats the fixing belt 21, a heater holding member 25 that holds the planar heater 23 in contact with the inner peripheral surface of the fixing belt 21, A pressure roller 27 that holds the fixing belt 21 between the sheet heater 23 and the sheet heater 23. In the following description, the axial direction X refers to the axial direction (front-rear direction) of the pressure roller 27. In the present embodiment, an example in which the fixing device 9 is arranged in a posture in which the pressure roller 27 is positioned below the fixing belt 21 is shown, but the fixing device 9 may be arranged in any posture.

  The fixing belt 21 is a belt formed in a cylindrical shape whose longitudinal direction is the axial direction X, has a predetermined inner diameter, and has a width longer than the width of the paper S. The fixing belt 21 is formed of a flexible material, and includes a base material layer, an elastic layer provided on the outer peripheral surface of the base material layer, and a release layer provided on the outer peripheral surface of the elastic layer. Yes. The base material layer is formed of a metal such as stainless steel or nickel alloy. The elastic layer is formed of silicon rubber or the like. The release layer is formed of a PFA tube or the like. A sliding layer may be formed on the inner peripheral surface of the base material layer. The sliding layer is formed of polyimide amide or PTFE.

  A stay 24 passes through a hollow portion of the fixing belt 21. The stay 24 is a groove-shaped member having an axial direction X as a longitudinal direction and opened on the pressure roller 27 side, and is formed of a metal such as stainless steel or an aluminum alloy. The length of the stay 24 is longer than the width of the fixing belt 21 and is arranged so that both ends of the stay 24 protrude from both ends of the fixing belt 21. The fixing belt 21 is supported by an arcuate belt guide (not shown) supported by the stay 24 and can be rotated along the belt guide.

  The planar heater 23 is formed in a substantially rectangular plate shape with the axial direction X as the longitudinal direction. The planar heater 23 includes a base material, a heat insulating layer, and a heat generating contact portion, and each portion is laminated in the order of the base material, the heat insulating layer, and the heat generating contact portion.

  The heater holding member 25 is formed in a substantially rectangular plate shape with the axial direction X as the longitudinal direction, and is fixed to the pressure roller 27 side of the stay 24. The length of the heater holding member 25 is longer than the width of the fixing belt 21. The heater holding member 25 is made of, for example, a heat resistant resin such as a liquid crystal polymer. A concave portion 251 is formed at a portion of the heater holding member 25 facing the pressure roller 27 so as to extend in the axial direction X. The planar heater 23 is fitted into the recess 251 so that the heat generating contact portion is exposed. The heater holding member 25 holds the planar heater 23 in contact with the inner peripheral surface of the fixing belt 21.

  The pressure roller 27 includes a shaft 271, a core metal 272, an elastic layer 273 provided on the outer peripheral surface of the core metal 272, and a release layer 274 provided on the outer peripheral surface of the elastic layer 273. The lengths in the axial direction X of the cored bar 272, the elastic layer 273, and the release layer 274 are equal to the length in the axial direction X of the fixing belt 21. The shaft 271 protrudes from both ends in the axial direction X of the cored bar 272. The shaft 271 and the core metal 272 are formed of a metal such as stainless steel or an aluminum alloy. The elastic layer 273 is formed of silicon rubber or the like. The release layer 274 is formed of a PFA tube or the like.

  Next, with reference to FIGS. 3 to 8, a configuration for supporting each of the above-described portions of the fixing device 9 will be described. 3 is a side view in the axial direction X of the transmission member 30, FIG. 4 is a side view in the axial direction X of the fixing device 9 to which the transmission member 30 is mounted, FIG. 5 is a perspective view of the transmission member 30, and FIG. FIG. 7 is a cross-sectional view of the holding member 40, and FIG. 8 is a perspective view of the pressure roller support member 50.

  Each part of the fixing device 9 is supported by a pair of transmission members 30, a pair of holding members 40, and a pair of pressure roller support members 50. The transmission member 30 is disposed so as to face both ends of the fixing belt 21, and transmits a load for pressing the planar heater 23 against the fixing belt 21 to the heater holding member 25. 27, a pressurizing region N in which the paper S is nipped and conveyed is formed. The holding member 40 holds the transmission member 30 and allows the transmission member 30 to slide in the radial direction (vertical direction) of the pressure roller 27. A bearing 28 and a holding member 40 are disposed on the pressure roller support member 50, and both ends of the shaft 271 of the pressure roller 27 are supported by the bearing 28.

  As shown in FIGS. 3 to 5, the transmission member 30 is a member that is open on the pressure roller 27 side and surrounds portions of the stay 24 that protrude from both ends of the fixing belt 21. The transmission member 30 is made of resin or the like. The transmission member 30 includes a load transmission portion 31 that faces the upper surface of the stay 24, and a sliding portion 32 that is formed in the direction of the pressure roller 27 from both ends of the load transmission portion 31 in the left-right direction.

  A sliding convex portion 33 is formed on the outer side surface of the sliding portion 32 so as to extend in the vertical direction (sliding direction). As will be described in detail later, the transmission member 30 is held by the holding member 40 and slides in the radial direction (vertical direction) of the pressure roller 27. A convex portion 34 is formed at the center of the upper surface of the load transmitting portion 31, and a load for pressing the planar heater 23 against the fixing belt 21 is applied to the convex portion 34 by a mechanism such as a spring. A convex portion 35 is formed at the center of the surface on the stay 24 side of the load transmitting portion 31, and the convex portion 35 contacts the stay 24.

  As shown in FIGS. 6 and 7, the holding member 40 is a generally U-shaped member opened on the upper side, and a pair of columnar portions 41 having a longitudinal direction in the vertical direction and a lower end of the pair of granular portions 41. And a connecting portion 42 to be connected. A sliding recess 45 is formed on the inner side surface of the columnar portion 41 so as to extend in the vertical direction (sliding direction). A concave portion 48 is formed on the outer side surface of the columnar portion 41 (the surface opposite to the sliding concave portion 45) so as to extend in the vertical direction. The sliding concave portion 45 is a groove having a shape corresponding to the sliding convex portion 33 of the sliding portion 32 of the transmission member 30. The transmission member 30 is held by the holding member 40 by fitting the sliding convex portion 33 into the sliding concave portion 45. Further, the transmission member 30 is allowed to slide in the radial direction (vertical direction) of the pressure roller 27, and movement of the transmission member 30 in a direction other than the radial direction is limited.

  A contact portion 46 that contacts an end portion 33T (lower end portion) of the sliding convex portion 33 on the pressure roller 27 side is formed at an end portion (lower end portion) of the sliding concave portion 45 on the pressure roller 27 side. . When the distance D (see FIG. 4) between the planar heater 23 and the shaft 271 of the pressure roller 27 reaches a predetermined minimum value, the contact portion 46 is on the pressure roller 27 side of the sliding convex portion 33. The distance D between the planar heater 23 and the shaft 271 of the pressure roller 27 is prevented from falling below the minimum value. This minimum value is either the minimum value of the distance at which the pressure roller 27 is not damaged due to compression or the minimum value of the distance at which the leakage from the planar heater 23 to the shaft 271 of the pressure roller 27 does not occur. The value is greater than

  As shown in FIG. 8, the pressure roller support member 50 is a plate-like member having a lower notch 51 and an upper notch 52. The lower cutout 51 is formed in a generally U shape corresponding to the outer peripheral surface of the bearing 28. The upper notch 52 is wider in the left-right direction than the lower notch 51, and the edge of the notch 52 has a thickness corresponding to the recess 48 of the holding member 40. The pressure roller support member 50 is made of a metal such as stainless steel or aluminum alloy, and is fixed to a housing (not shown) of the fixing device 9.

  Next, an assembling procedure of the fixing device 9 having the above configuration will be described with reference to FIGS. 9 to 12 are perspective views showing an assembling procedure of the fixing device 9. 13 is a cross-sectional view of the holding member 40 and the transmission member 30 in the state of FIG.

  First, as shown in FIG. 9, the bearing 28 is disposed in the lower cutout 51 of the pressure roller support member 50, and the shaft 271 of the pressure roller 27 is fitted into the bearing 28. In the present embodiment, a sliding bearing having an upper opening is used as the bearing 28. Next, as shown in FIG. 10, pressure is applied by inserting the edge of the upper notch 52 of the pressure roller support member 50 into the recess 48 of the holding member 40 and moving the holding member 40 downward. The holding member 40 is fitted into the roller support member 50.

  Next, the fixing belt 21 is disposed. Specifically, as shown in FIG. 11, in the state where the heater holding member 25 holding the planar heater 23 is fixed to the stay 24 and these are inserted into the hollow portion of the fixing belt 21, A pair of transmission members 30 are put on both ends of the stay 24 protruding from both ends. The sliding convex portion 33 of the transmission member 30 is fitted into the sliding concave portion 45 of the holding member 40, and the transmission member 30 is slid in the direction of the pressure roller 27 (downward). FIG. 12 shows a state in which the fixing belt 21 contacts the pressure roller 27 and the transmission member 30 stops sliding. At this time, as shown in FIG. 13, the contact portion 46 is not in contact with the end portion 33 </ b> T (lower end portion) of the sliding convex portion 33 on the pressure roller 27 side. Further, the connecting portion 42 of the holding member 40 is located between the shaft 271 and the planar heater 23.

  Next, the fixing operation of the fixing device 9 having the above-described configuration will be described with reference to FIGS. First, a load for pressing the planar heater 23 against the fixing belt 21 is applied to the convex portion 34 by a mechanism such as a spring. The load applied to the convex portion 34 is transmitted to the heater holding member 25 via the convex portion 35 and the stay 24, and the planar heater 23 is pressed against the fixing belt 21. Thus, a pressure region N in which the paper S is sandwiched and conveyed is formed between the fixing belt 21 and the pressure roller 27. At this time, the transmission member 30 is pushed into the pressure roller 27 side as compared with the state shown in FIGS. It does not touch the lower end. Note that the fixing device 9 may have a function of controlling the load according to the type of paper, the set image quality, and the like, but in this case, the contact portion 46 has the sliding protrusion 33 even when the load is maximum. It does not contact the end portion 33T (lower end portion) on the pressure roller 27 side.

  When the pressure roller 27 is driven and rotated in this state, the fixing belt 21 is driven to rotate in a direction opposite to the rotation direction of the pressure roller 27. At the same time, the planar heater 23 is driven to heat the fixing belt 21. The fixing belt 21 is heated to a predetermined control temperature (for example, 160 ° C.). After the fixing belt 21 is heated in this way, the sheet S on which the toner image is transferred is conveyed to the pressure area N. In the pressure region N, the sheet S is nipped between the fixing belt 21 and the pressure roller 27 and is conveyed in the determined conveyance direction Y. At this time, the sheet S is heated by the fixing belt 21 and is pressed by the pressure roller 27 and the fixing belt 21, and the toner image is fixed on the sheet S. The sheet S on which the toner image is fixed is separated from the fixing belt 21 and conveyed along the conveyance path 15.

  When the distance D between the planar heater 23 and the shaft 271 of the pressure roller 27 reaches a predetermined minimum value, the holding member 40 is located at a portion facing the transmission member 30 or the shaft 271 of the heater holding member 25. The contact part 46 which contacts is provided. This minimum value is a value greater than or equal to the minimum value of the distance at which the pressure roller 27 is not damaged by compression and the minimum distance at which the leakage from the planar heater 23 to the shaft 271 does not occur. is there. Therefore, the distance D between the planar heater 23 and the shaft 271 of the pressure roller 27 is the minimum value of the distance at which the pressure roller 27 is not damaged by compression, and the shaft 271 of the pressure roller 27 from the planar heater 23. Never go below the minimum distance at which no leakage occurs.

  For example, even if the pressure roller 27 is compressed more than necessary due to component tolerances such as a spring and the pressure roller 27, the distance D between the planar heater 23 and the shaft 271 of the pressure roller 27 is compressed. The pressure roller 27 does not fall below the minimum distance that does not cause damage. Even if the thickness of the elastic layer 273 of the pressure roller 27 is reduced due to the decrease in hardness over time, the distance D between the planar heater 23 and the shaft 271 of the pressure roller 27 is equal to the planar heater 23. From the minimum distance at which no electric leakage from the pressure roller 27 to the shaft 271 occurs. Therefore, according to the present embodiment, it is possible to prevent damage to the pressure roller 27 due to excessive compression, and leakage from the planar heater 23 to the shaft 271 of the pressure roller 27.

  In the present embodiment, the holding member 40 is formed of an insulator, and the connecting portion 42 that is a part of the holding member 40 is located between the shaft 271 and the planar heater 23. Compared with the case where an insulator does not exist between the sheet heater 23 and the sheet heater 23, the effect of preventing electric leakage from the planar heater 23 to the shaft 271 of the pressure roller 27 can be enhanced.

  In the above embodiment, the minimum value of the distance D between the planar heater 23 and the shaft 271 of the pressure roller 27 is the minimum value of the distance at which the pressure roller 27 is not damaged by the compression, and the planar heater 23. Although an example is shown in which the minimum value of the distance at which no electric leakage to the shaft 271 of the pressure roller 27 does not occur, whichever is greater, the surface heater 23 and the shaft 271 of the pressure roller 27 The minimum value of the distance D may be a value equal to or greater than the minimum value of the distance at which the pressure roller 27 is not damaged by the compression. According to this configuration, it is possible to prevent the pressure roller 27 from being damaged due to excessive compression. Alternatively, the minimum value of the distance D between the planar heater 23 and the shaft 271 of the pressure roller 27 is equal to or greater than the minimum value of the distance at which no leakage from the planar heater 23 to the shaft 271 of the pressure roller 27 occurs. May be. According to this configuration, leakage from the planar heater 23 to the shaft 271 of the pressure roller 27 can be prevented.

  In the above-described embodiment, a sliding bearing having an upper opening is illustrated as the bearing 28 (see FIGS. 4 and 9 and the like). However, as the bearing 28, a sliding bearing or a bearing having no opening on the upper side is used. Also good.

  In the above-described embodiment, an example in which the sliding convex portion 33 is formed on the transmission member 30 and the sliding concave portion 45 is formed on the holding member 40 has been described. However, the sliding concave portion is formed on the transmission member 30 and the holding member is formed. A sliding protrusion may be formed on 40.

  In the above-described embodiment, an example is shown in which the contact portion 46 that contacts the end portion of the sliding convex portion 33 on the pressure roller 27 side is formed at the end portion of the sliding concave portion 45 on the pressure roller 27 side. A convex contact portion that contacts the lower end of the sliding portion 32 of the transmission member 30 may be formed on the surface where the sliding recess 45 is provided. Or the convex contact part which contacts the lower surface of the heater holding member 25 may be formed in the surface in which the sliding recessed part 45 is provided. In short, it is only necessary that the second holding portion 42 be formed with a contact portion that contacts a portion of the transmission member 30 or the heater holding member 25 that faces the shaft 271.

  In the above embodiment, the heater holding member 25 is fixed to the stay 24. However, the stay 24 and the heater holding member 25 may be integrally formed. For example, a cylindrical member having a rectangular cross section may be configured to function as the stay 24 and the heater holding member 25.

  Although FIG. 1 of the above embodiment shows a schematic diagram of a full-color printer, the present invention may be applied to a monochrome printer.

  The above description of the embodiments of the present invention describes preferred embodiments of the fixing device and the image forming apparatus according to the present invention, and thus may have various technically preferable limitations. The technical scope of the present invention is not limited to these embodiments unless specifically described to limit the present invention. That is, the above-described components in the embodiment of the present invention can be appropriately replaced with existing components and the like, and various variations including combinations with other existing components are possible. The description of the embodiment of the present invention described above does not limit the contents of the invention described in the claims.

1 Printer (image forming device)
7 Image forming unit 9 Fixing device 21 Fixing belt 23 Planar heater 25 Heater holding member 27 Pressure roller 271 Shaft 30 Transmission member 33 Sliding convex portion 40 Holding member 45 Sliding concave portion 46 Contact portion

Claims (7)

A cylindrical fixing belt;
A planar heater for heating the fixing belt;
A heater holding member for holding the planar heater in contact with the inner peripheral surface of the fixing belt;
A pressure roller for sandwiching the fixing belt with the planar heater;
The fixing belt is disposed so as to oppose both ends of the fixing belt, and transmits a load for pressing the planar heater against the fixing belt to the heater holding member, so that the fixing belt and the pressure roller are interposed. A pair of transmission members forming a pressurizing region where the paper is nipped and conveyed;
The transmission member is held, the transmission member is allowed to slide in the radial direction of the pressure roller, and the distance between the planar heater and the axis of the pressure roller reaches a predetermined minimum value. And a pair of holding members having a contact portion that contacts a portion of the transmission member or the heater holding member facing the axis of the pressure roller.   The minimum value is the larger one of the minimum value of the distance at which the pressure roller is not damaged by compression and the minimum value of the distance at which the leakage from the planar heater to the shaft of the pressure roller does not occur The fixing device according to claim 1, wherein the fixing device has the above value.   The fixing device according to claim 1, wherein the minimum value is a value equal to or greater than a minimum value of a distance at which the pressure roller is not damaged by compression.   The fixing device according to claim 1, wherein the minimum value is a value that is equal to or greater than a minimum value of a distance at which no leakage occurs from the planar heater to the shaft of the pressure roller. The transmission member includes a sliding protrusion formed to extend in the sliding direction,
The holding member includes a sliding recess corresponding to the sliding protrusion,
The said contact part is formed in the edge part by the side of the said pressure roller of the said sliding recessed part, and contacts the edge part by the side of the said pressure roller of the said sliding convex part, The Claim 1 thru | or 4 characterized by the above-mentioned. The fixing device according to claim 1.   The fixing device according to claim 2, wherein the holding member is formed of an insulator, and a part of the holding member is located between a shaft of the pressure roller and the planar heater. . An image forming unit for forming a toner image on the paper;
An image forming apparatus comprising: the fixing device according to claim 1, wherein the toner image is fixed on the sheet.

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