JP6287692B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

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

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus such as a copying machine, a printer, a fax machine, or a multifunction machine includes a fixing device that fixes a toner image on a recording medium such as paper.

  For example, there is a fixing device including a fixing belt, a pressing member that presses against the fixing belt to form a fixing nip, and a pressing member that presses the fixing belt toward the pressing member (see Patent Document 1). ). In the fixing device having such a configuration, usually, the pressure member is driven to rotate by a driving source, and the fixing belt is rotated by following the pressure member, and the fixing belt is slid with respect to the pressing member.

JP 2013-20106 A

  When such a configuration is adopted, there is a possibility that the linear velocity of the recording medium varies in the fixing nip. In addition, when the above configuration is adopted, the conveyance of the recording medium tends to become unstable.

  In view of the above circumstances, an object of the present invention is to suppress variations in linear velocity of a recording medium and to stably convey the recording medium.

  The fixing device of the present invention comprises a fixing belt that is rotatably provided, a fixing nip formed by pressure contact with the fixing belt, and a pressure member that is rotatably provided, and the fixing belt facing the pressure member side. A pressing member that presses the pressure member, a drive source that rotationally drives the pressure member, and a transport roller that is disposed downstream of the fixing nip in the transport direction of the recording medium and is rotationally driven by the drive source or another drive source The conveyance roller extends in the direction of the rotation axis of the fixing belt, a first conveyance unit provided around the conveyance axis, and provided around the conveyance axis, and the first conveyance unit. And an outer diameter of the second transport unit is different from an outer diameter of the first transport unit.

  As described above, by rotating and driving the conveyance roller disposed on the downstream side of the fixing nip in the recording medium conveyance direction, even when the linear velocity of the recording medium varies in the fixing nip, the recording medium becomes the conveyance roller. When it reaches, the linear velocity of the recording medium can be made uniform, and variations in the linear velocity of the recording medium can be suppressed.

  Moreover, since the outer diameter of the second transport unit is different from the outer diameter of the first transport unit as described above, the larger one of the first transport unit and the second transport unit is used as the main transport unit. In addition, it is possible to use the smaller one of the first conveyance unit and the second conveyance unit as an auxiliary conveyance unit. Accordingly, the conveyance force of the first conveyance unit and the conveyance force of the second conveyance unit are less likely to compete, and the recording medium can be conveyed stably.

  The outer diameter of the second transport unit may be smaller than the outer diameter of the first transport unit.

  By adopting such a configuration, it is possible to improve the transportability of the recording medium.

  The outer diameter of the second transport unit may be larger than the outer diameter of the first transport unit.

  By adopting such a configuration, the recording medium can be transported while being pulled outward in the rotation axis direction of the fixing belt, so that the recording medium is less likely to wrinkle.

  The apparatus further includes a driven roller that is in pressure contact with the conveyance roller, the conveyance roller being disposed closer to the pressure member than the recording medium conveyance path, and the driven roller being closer to the fixing belt than the recording medium conveyance path. It may be arranged.

  By adopting such a configuration, the conveyance roller is disposed on the non-image surface side of the paper. Along with this, it is possible to suppress the influence on the image accompanying the conveyance of the recording medium by the conveyance roller.

  The surface on the fixing nip side of the pressing member is inclined toward the pressure member side toward the downstream side in the conveyance direction of the recording medium, and the rotation center of the driven roller is closer to the recording medium than the rotation center of the conveyance roller. You may be located in the conveyance direction upstream.

  As described above, the surface of the pressing member on the fixing nip side is inclined toward the pressure member side toward the downstream side in the conveyance direction of the recording medium, so that the recording medium can be easily separated from the fixing belt. In addition, since the rotation center of the driven roller is positioned upstream of the rotation center of the conveyance roller in the conveyance direction of the recording medium, the recording medium that has passed through the fixing nip is formed in the conveyance nip formed by the conveyance roller and the driven roller. Easy to introduce.

  The image forming apparatus of the present invention includes any one of the fixing devices described above.

  According to the present invention, it is possible to suppress a variation in linear velocity of the recording medium and to stably convey the recording medium.

1 is a schematic diagram illustrating an outline of a printer according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a fixing device according to an embodiment of the present invention. FIG. 3 is a perspective view illustrating a conveyance roller and a driven roller in the fixing device according to the embodiment of the present disclosure. FIG. 9 is a perspective view showing a conveyance roller and a driven roller in a fixing device according to another different embodiment of the present invention.

  First, the overall configuration of the printer 1 (image forming apparatus) will be described with reference to FIG.

  The printer 1 includes a box-shaped printer main body 2, and a paper feed cassette 3 that stores paper (recording medium) is accommodated in a lower portion of the printer main body 2. A paper discharge tray is disposed on the upper surface of the printer main body 2. 4 is provided. An upper cover 5 is attached to the upper surface of the printer main body 2 so as to be openable and closable on the side of the paper discharge tray 4, and a toner container 6 is accommodated below the upper cover 5.

  An exposure unit 7 composed of a laser scanning unit (LSU) is disposed below the paper discharge tray 4 above the printer body 2, and an image forming unit 8 is provided below the exposure unit 7. Yes. The image forming unit 8 is rotatably provided with a photosensitive drum 10 as an image carrier. Around the photosensitive drum 10, a charger 11, a developing device 12, a transfer roller 13, and a cleaning device are provided. The apparatus 14 is disposed along the rotation direction of the photosensitive drum 10 (see arrow X in FIG. 1).

  A paper transport path 15 is provided inside the printer main body 2. A paper feed unit 16 is provided at the upstream end of the conveyance path 15, and a transfer unit 17 configured by the photosensitive drum 10 and the transfer roller 13 is provided at a middle portion of the conveyance path 15. Is provided with a fixing device 18, and a paper discharge unit 19 is provided at the downstream end of the conveyance path 15. A reverse path 20 for double-sided printing is formed below the transport path 15.

  Next, an image forming operation of the printer 1 having such a configuration will be described.

  When the printer 1 is turned on, various parameters are initialized, and initial setting such as temperature setting of the fixing device 18 is executed. Then, when image data is input from a computer or the like connected to the printer 1 and an instruction to start printing is given, an image forming operation is executed as follows.

  First, after the surface of the photosensitive drum 10 is charged by the charger 11, exposure corresponding to the image data is performed on the photosensitive drum 10 by laser light from the exposure device 7 (see the two-dot chain line P in FIG. 1). The electrostatic latent image is formed on the surface of the photosensitive drum 10. Next, the electrostatic latent image is developed by the developing device 12 into a toner image with toner.

  On the other hand, the sheet taken out from the sheet cassette 3 by the sheet feeding unit 16 is conveyed to the transfer unit 17 in synchronization with the above-described image forming operation, and the toner image on the photosensitive drum 10 is transferred to the sheet by the transfer unit 17. Is transcribed. The sheet on which the toner image has been transferred is conveyed downstream in the conveyance path 15 and enters the fixing device 18 where the toner image is fixed on the sheet. The paper on which the toner image is fixed is discharged from the paper discharge unit 19 to the paper discharge tray 4. The toner remaining on the photosensitive drum 10 is collected by the cleaning device 14.

  Next, the fixing device 18 will be described in detail. Hereinafter, for convenience of explanation, the front side of the sheet in FIG. 2 is defined as the front side (front side) of the fixing device 18. Arrows Fr, Rr, L, R, U, and Lo that are appropriately attached to the drawings respectively indicate the front side, the rear side, the left side, the right side, the upper side, and the lower side of the fixing device 18. An arrow Y in FIG. 2 indicates the sheet conveyance direction (in this embodiment, the left-right direction). 3 and FIG. 4, arrow I indicates the inner side in the front-rear direction, and arrow O in FIGS. 3 and 4 indicates the outer side in the front-rear direction.

  As shown in FIG. 2 and the like, the fixing device 18 includes a box-shaped fixing frame 21, a fixing belt 22 accommodated in the upper center of the fixing frame 21, and a pressure accommodated in the lower center of the fixing frame 21. A roller 23 (pressure member), a heater 24 (heat source) disposed on the inner diameter side of the fixing belt 22, a reflection member 25 disposed on the lower side of the heater 24 on the inner diameter side of the fixing belt 22, and the fixing belt 22 A support member 26 disposed below the reflecting member 25 on the inner diameter side thereof, spacers 27 disposed on both front and rear ends of the reflecting member 25 (only the rear spacer 27 is shown in FIG. 2), a fixing belt 22, a pressing member 28 disposed below the support member 26 on the inner diameter side, and a conveyance roller 29 and a driven roller 30 housed on the left side of the fixing frame 21 are provided. To have.

  The fixing frame 21 is formed of sheet metal. The fixing frame 21 includes an upper frame portion 31 and a lower frame portion 32 that are connected to each other.

  Belt mounting bases 33 are fixed to both front and rear end portions of the upper frame portion 31. Each belt mount 33 is provided with an arc-shaped belt support 34. An annular meandering restriction ring 35 is provided on the outer periphery of the belt support portion 34.

  A swing frame 36 is provided at both front and rear ends of the lower frame portion 32. A fulcrum portion 37 is provided on the right end side of each swing frame 36, and each swing frame 36 is configured to swing around the fulcrum portion 37.

  The fixing belt 22 has a substantially cylindrical shape that is long in the front-rear direction. The fixing belt 22 has flexibility and is endless in the circumferential direction. The fixing belt 22 includes, for example, a base material layer, an elastic layer provided around the base material layer, and a release layer that covers the elastic layer. The base material layer of the fixing belt 22 is formed of a metal such as SUS, for example. The base material layer of the fixing belt 22 may be formed of a resin such as PI (polyimide). The elastic layer of the fixing belt 22 is made of, for example, silicon rubber. The release layer of the fixing belt 22 is formed of, for example, a PFA tube. In each figure, each layer (base material layer, elastic layer, release layer) of the fixing belt 22 is displayed without being particularly distinguished.

  At both front and rear end portions of the fixing belt 22, belt support portions 34 provided on the belt mounting bases 33 of the upper frame portion 31 are inserted. As a result, the fixing belt 22 is rotatably supported by the upper frame portion 31. The fixing belt 22 is provided to be rotatable around a rotation axis A extending in the front-rear direction. That is, in the present embodiment, the rotation axis direction of the fixing belt 22 is the front-rear direction. The front and rear end faces of the fixing belt 22 are disposed on the inner side in the front-rear direction of the meandering restriction ring 35 provided on each belt mount 33 of the upper frame portion 31. As a result, the meandering of the fixing belt 22 (shift toward one side in the front-rear direction) is restricted.

  The pressure roller 23 has a substantially cylindrical shape that is long in the front-rear direction. The pressure roller 23 includes, for example, a cylindrical core member 40, an elastic layer 41 provided around the core member 40, and a release layer (not shown) that covers the elastic layer 41. ing. The core material 40 of the pressure roller 23 is made of metal such as iron, for example. The elastic layer 41 of the pressure roller 23 is made of, for example, silicon rubber. The release layer of the pressure roller 23 is formed by, for example, a PFA tube.

  The pressure roller 23 is disposed on the lower side (outer diameter side) of the fixing belt 22. The pressure roller 23 is in pressure contact with the fixing belt 22, and a fixing nip N is formed between the fixing belt 22 and the pressure roller 23. The pressure roller 23 is rotatably supported at the center in the longitudinal direction of the swing frame 36 of the lower frame portion 32 (in the present embodiment, the center in the left-right direction), and the swing frame 36 is centered on the fulcrum portion 37. The pressure roller 23 moves up and down as it swings, so that the pressure in the fixing nip N is switched.

  The pressure roller 23 is connected to a drive source 42 configured by a motor or the like, and is configured such that the pressure roller 23 is rotationally driven by the drive source 42. The drive source 42 is schematically shown in FIG. 2, and the position of the drive source 42 on the drawing does not necessarily match the actual position of the drive source 42. A conveyance guide 49 is provided on the right side of the pressure roller 23.

  The heater 24 is composed of, for example, a halogen heater. The heater 24 is disposed above the reflecting member 25, the support member 26, and the pressing member 28 (on the side away from the pressure roller 23). Both front and rear end portions of the heater 24 are attached to the upper frame portion 31.

  The reflection member 25 has a long shape in the front-rear direction. The reflecting member 25 is made of a metal such as bright aluminum, for example. The reflection member 25 is disposed between the heater 24 and the support member 26. The reflecting member 25 has a U-shape that is convex upward. The upper surface (surface on the heater 24 side) of the reflection member 25 is a reflection surface (mirror surface) that reflects the radiant heat radiated from the heater 24 toward the inner peripheral surface of the fixing belt 22.

  The support member 26 has a shape that is long in the front-rear direction. The support member 26 is formed of sheet metal such as SECC (galvanized steel sheet). The support member 26 is formed by combining the upper support portion 43 and the lower support portion 44.

  The upper support portion 43 of the support member 26 has a U-shape that is convex upward. A portion extending from the center in the up-down direction to the upper end of the upper support 43 is inserted into a recess formed on the lower side of the reflection member 25. An engagement piece 45 that extends downward from the lower right end of the upper support 43 is provided at the lower left end of the upper support 43.

  The lower support portion 44 of the support member 26 has a U-shape that protrudes downward. The lower support portion 44 is inserted into a recess formed on the lower side of the upper support portion 43.

  Each spacer 27 is formed of a resin such as LCP (liquid crystal polymer), PPS (polyphenylene sulfide), PEEK (polyether ether ketone), and the like.

  Each spacer 27 includes a bottom wall portion 46 and side wall portions 47 bent upward from the left and right end portions of the bottom wall portion 46. The bottom wall portion 46 is sandwiched between the front and rear end portions of the reflecting member 25 and the front and rear end portions of the upper support portion 43 of the support member 26. Accordingly, the reflecting member 25 and the support member 26 are not in contact with each other.

  The pressing member 28 has a shape that is long in the front-rear direction. The pressing member 28 is formed of a heat resistant resin such as LCP (liquid crystal polymer). The pressing member 28 is supported from above by the support member 26. An engagement recess 48 is provided at the left end of the pressing member 28, and the engagement piece 45 of the upper support 43 of the support member 26 is engaged with the engagement recess 48.

  The lower surface (the surface on the fixing nip N side) of the pressing member 28 is inclined downward (to the pressure roller 23 side) toward the left side (downstream side in the sheet conveyance direction). The lower surface of the pressing member 28 presses the fixing belt 22 downward (pressure roller 23 side).

  The transport roller 29 is disposed on the downstream side of the fixing nip N in the paper transport direction (see arrow Y in FIG. 2). The conveyance roller 29 is disposed below the paper conveyance path 15 (on the pressure roller 23 side). The transport roller 29 is connected to a drive source 42 and is configured such that the transport roller 29 is rotationally driven by the drive source 42.

  As shown in FIG. 3, the transport roller 29 includes a transport shaft 50 that extends in the front-rear direction, a pair of front and rear first transport portions 51 that are provided around the transport shaft 50, and a transport shaft 50 that is provided around each transport shaft 50. And a pair of front and rear second transport units 52 disposed on the outer side in the front-rear direction than the first transport unit 51.

  Both front and rear ends of the conveyance shaft 50 of the conveyance roller 29 are pivotally supported by the fixing frame 21. Thereby, the conveyance roller 29 can rotate around the axis S of the conveyance shaft 50.

  Each 1st conveyance part 51 and each 2nd conveyance part 52 of the conveyance roller 29 comprise cylindrical shape, for example, are formed with elastic materials, such as rubber | gum. Each 1st conveyance part 51 and each 2nd conveyance part 52 are arrange | positioned at intervals in the front-back direction. The outer diameter of each second transport unit 52 is smaller than the outer diameter of each first transport unit 51. That is, the outer diameter of each second transport unit 52 is different from the outer diameter of each first transport unit 51.

  As shown in FIG. 2, the driven roller 30 is disposed on the downstream side of the fixing nip N in the paper transport direction (see arrow Y in FIG. 2). The driven roller 30 is disposed on the upper side (fixing belt 22 side) of the paper conveyance path 15.

  As shown in FIG. 3, the driven roller 30 includes a driven shaft 60 that extends in the front-rear direction, a pair of front and rear first driven portions 61 that are provided around the driven shaft 60, and a driven shaft 60 that is provided around the driven shaft 60. And a pair of front and rear second driven portions 62 disposed on the outer side in the front-rear direction than the first driven portion 61.

  Both front and rear ends of the driven shaft 60 of the driven roller 30 are supported by the fixing frame 21. As a result, the driven roller 30 can rotate around the axis T of the driven shaft 60. As shown in FIG. 2, the axis T of the driven shaft 60 (the rotation center of the driven roller 30) is on the right side (upstream in the sheet conveyance direction) with respect to the axis S of the conveyance shaft 50 (the rotation center of the conveyance roller 29). ).

  As shown in FIG. 3, each first driven portion 61 and each second driven portion 62 of the driven roller 30 have a cylindrical shape, and are formed of a metal material such as iron, for example. Each first driven portion 61 and each second driven portion 62 are arranged at intervals in the front-rear direction. The outer diameter of each second driven portion 62 is the same as the outer diameter of each first driven portion 61. Each first driven portion 61 is in pressure contact with each first transport portion 51 of the transport roller 29, and a first transport nip N <b> 1 is formed between each first transport portion 51 and each first driven portion 61. ing. Each second driven portion 62 is in pressure contact with each second transport portion 52 of the transport roller 29, and a second transport nip N2 is formed between each second transport portion 52 and each second driven portion 62. ing. As described above, since the outer diameter of each second transport unit 52 is smaller than the outer diameter of each first transport unit 51, the nip pressure (pressing force) of each second transport nip N2 is the nip of each first transport nip N1. Less than the pressure (pressing force).

  As shown in FIG. 2, a lower conveyance guide 64 is provided between the pressure roller 23 and the conveyance roller 29. The lower conveyance guide 64 is disposed below the sheet conveyance path 15. An upper conveyance guide 65 is provided between the fixing belt 22 and the driven roller 30. The upper conveyance guide 65 is disposed above the sheet conveyance path 15.

  In the fixing device 18 configured as described above, when the toner image is fixed on the paper, the pressure roller 23 is rotationally driven by the drive source 42 (see arrow B in FIG. 2). When the pressure roller 23 rotates in this manner, the fixing belt 22 that is in pressure contact with the pressure roller 23 is rotated following the pressure roller 23 (see arrow C in FIG. 2). When the fixing belt 22 rotates in this way, the fixing belt 22 slides with respect to the pressing member 28.

  Further, when the toner image is fixed on the paper, the heater 24 is energized to generate heat and radiate heat. A part of the radiant heat radiated from the heater 24 is directly irradiated onto and absorbed by the inner peripheral surface of the fixing belt 22 as indicated by an arrow D in FIG. Further, another part of the radiant heat radiated from the heater 24 is reflected toward the inner peripheral surface of the fixing belt 22 by the upper surface of the reflecting member 25 as shown by an arrow E in FIG. Absorbed by the inner peripheral surface. Due to the above operation, the fixing belt 22 is heated by the heater 24. In this state, when the paper passes through the fixing nip N, the toner image is heated and melted, and the toner image is fixed on the paper.

  Further, when the toner image is fixed on the paper, the drive source 42 rotates the transport roller 29. When the transport roller 29 rotates in this way, the driven roller 30 that is in pressure contact with the transport roller 29 rotates following the transport roller 29. Accordingly, the sheet that has passed through the fixing nip N is conveyed to the left side (downstream in the sheet conveying direction) by the conveying roller 29 and the driven roller 30 and is discharged from the fixing device 18. At this time, the linear speeds of the conveyance roller 29 and the driven roller 30 are, for example, the same as the linear speeds of the fixing belt 22 and the pressure roller 23 or faster than the linear speeds of the fixing belt 22 and the pressure roller 23. .

  In the present embodiment, the fixing belt 22 is rotated by the rotation of the pressure roller 23, and the fixing belt 22 is slid with respect to the pressing member 28. In the case of adopting such a configuration, if slip occurs between the pressure roller 23 and the fixing belt 22, the rotation transmission from the pressure roller 23 to the fixing belt 22 becomes insufficient. As a result, the linear speed of the sheet temporarily decreases in the fixing nip N, and accordingly, the linear speed of the sheet may vary in the fixing nip N. In order to suppress such a variation in the linear velocity of the paper, it is conceivable to control the rotational speed of the drive source 42, but in this case, the control of the drive source 42 becomes complicated.

  Therefore, in the present embodiment, the conveyance roller 29 disposed on the downstream side of the fixing nip N in the sheet conveyance direction is rotationally driven by the drive source 42. By adopting such a configuration, even when a variation in the linear velocity of the paper occurs in the fixing nip N, the linear velocity of the paper is made uniform when the paper reaches the transport roller 29, and the variation in the linear velocity of the paper. Can be suppressed.

  Moreover, since the outer diameter of the 2nd conveyance part 52 is smaller than the outer diameter of the 1st conveyance part 51, the 1st conveyance part 51 is utilized as a main conveyance part, and the 2nd conveyance part 52 is used as an auxiliary conveyance part. It can be used. Accordingly, the transport force of the first transport unit 51 and the transport force of the second transport unit 52 are less likely to compete, and the paper can be transported stably. Further, since the outer diameter of the second transport unit 52 is smaller than the outer diameter of the first transport unit 51 as described above, it is possible to improve the transportability of the paper.

  Further, the transport roller 29 is disposed on the lower side (pressure roller 23 side) than the paper transport path 15, and the driven roller 30 is disposed on the upper side (fixing belt 22 side) than the paper transport path 15. By adopting such a configuration, the transport roller 29 is disposed on the non-image surface side of the paper. Along with this, it is possible to suppress the influence on the image accompanying the conveyance of the sheet by the conveyance roller 29.

  Further, the lower surface (the surface on the fixing nip N side) of the pressing member 28 is inclined downward (to the pressure roller 23 side) toward the left side (downstream side in the sheet conveyance direction). Therefore, it becomes easy to separate the paper from the fixing belt 22. Further, the axis T (the rotation center of the driven roller 30) of the driven shaft 60 is located on the right side (upstream in the sheet conveyance direction) with respect to the axis S (the rotation center of the conveyance roller 29) of the conveyance shaft 50. Further, it becomes easy to introduce the paper that has passed through the fixing nip N into the conveyance nips N1 and N2 formed by the conveyance roller 29 and the driven roller 30.

  In this embodiment, the case where the pressure roller 23 and the conveyance roller 29 are rotationally driven by the single drive source 42 was demonstrated. On the other hand, in another different embodiment, the pressure roller 23 and the transport roller 29 may be rotationally driven by separate drive sources.

  In the present embodiment, as illustrated in FIG. 3, the case where the outer diameter of each second transport unit 52 is smaller than the outer diameter of each first transport unit 51 has been described. On the other hand, in other different embodiments, as shown in FIG. 4, the outer diameter of each second transport unit 52 may be larger than the outer diameter of each first transport unit 51. By adopting such a configuration, the sheet can be conveyed while being pulled outward in the front-rear direction, so that the sheet is less likely to wrinkle.

  In the present embodiment, the case where a halogen heater is used as the heater 24 has been described. However, in another different embodiment, a ceramic heater or the like may be used as the heater.

  In this embodiment, the case where the configuration of the present invention is applied to the printer 1 has been described. However, in another different embodiment, the configuration of the present invention is applied to other image forming apparatuses such as a copying machine, a facsimile machine, and a multifunction machine. It is also possible.

1 Printer (image forming device)
15 Transport Path 18 Fixing Device 22 Fixing Belt 23 Pressure Roller (Pressure Member)
28 Pressing Member 29 Conveying Roller 30 Driven Roller 42 Drive Source 50 Conveying Axis 51 First Conveying Unit 52 Second Conveying Unit A (Rotating shaft)
N Fixing nip S Center of rotation (of transport roller) T Center of rotation (of driven roller)

Claims (4)

A fixing belt provided rotatably;
A pressure member provided in a rotatable manner to form a fixing nip by pressing against the fixing belt;
A pressing member that presses the fixing belt toward the pressing member;
A drive source for rotationally driving the pressure member;
A transport roller disposed downstream of the fixing nip in the transport direction of the recording medium and rotated by the drive source or another drive source;
A driven roller in pressure contact with the transport roller;
A support member disposed on the inner diameter side of the fixing belt and supporting the pressing member;
A heat source disposed on the inner diameter side of the fixing belt and radiating radiant heat;
A reflective member that is disposed between the heat source and the support member and reflects radiant heat radiated from the heat source toward an inner peripheral surface of the fixing belt;
A spacer that is sandwiched between the reflective member and the support member, and that keeps the reflective member and the support member in non-contact ,
The transport roller is
A conveying shaft extending in the direction of the rotation axis of the fixing belt;
A first transport section provided around the transport shaft;
A second transport unit provided around the transport shaft and disposed on the outer side in the rotation axis direction than the first transport unit;
The driven roller is
A first driven portion that is in pressure contact with the first transport portion;
A second follower that is in pressure contact with the second transport unit;
The outer diameter of the second transport unit is larger than the outer diameter of the first transport unit, the outer diameter of the second driven unit is the same as the outer diameter of the first driven unit, and the first driven unit And the second driven portion are arranged on the same axis . The transport roller is disposed closer to the pressure member than the transport path of the recording medium,
The fixing device according to claim 1 , wherein the driven roller is disposed closer to the fixing belt than a conveyance path of the recording medium. The surface on the fixing nip side of the pressing member is inclined toward the pressure member side toward the downstream side in the conveyance direction of the recording medium,
The fixing device according to claim 2 , wherein a rotation center of the driven roller is located upstream of a rotation center of the conveyance roller in a conveyance direction of the recording medium. An image forming apparatus characterized in that it comprises a fixing device according to any one of claims 1-3.

Images