JP2018049135A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of a fixing device that fixes a toner image to a recording medium at a nip part formed by a pressure member and a fixing belt by bringing a rotating pressure member into pressure contact with the fixing belt wound around a heating-side member and a nip forming member to drive to rotate the fixing belt.SOLUTION: A fixing device 30 fixes a toner image t to a recording medium S at a nip part at which tension is caused to act on a fixing belt 33 wound around a heating roller 31 and a nip forming member 32 by a pressing member 37 and the fixing belt is brought into contact with a pressure roller 34. The heating roller is urged by the pressing member in a direction separating from the nip part toward a direction inclined with respect to a line connecting the center of a heating-side member and the center of the nip part, and at least part of the pressing member is arranged outside the fixing belt.SELECTED DRAWING: Figure 2

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, and a composite machine of these, and a fixing device that fixes a toner image transferred to a recording medium on the recording medium. In particular, a fixing belt that is wound around the heating side member and the nip forming member, and a pressure member that is rotationally driven by being pressed against the nip forming member so as to sandwich the fixing belt, In a state in which tension is applied to the fixing belt by the pressing member, the fixing belt is pressed against the pressure member by the nip forming member and is rotationally driven, and toner is generated at the nip portion where the fixing belt and the pressure member are pressed. The fixing device for fixing an image to a recording medium is characterized in that the fixing device is downsized to reduce heat loss during heat fixing and to save energy.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine, a printer, a facsimile, and a composite machine of these, a toner image transferred to a recording medium is fixed on the recording medium by a fixing device.

  In such a fixing device, the endless fixing belt is urged by the pressing member in order to save energy when fixing the toner image transferred to the recording medium onto the sheet by heat and pressure. It is wound around the heating roller and the heating side roller, and is rotated with the pressure roller being pressed against the heating side roller via this fixing belt, and the fixing belt and the pressure roller are pressed against each other. A toner image is fixed on the recording medium at the nip portion.

  In recent years, as shown in Patent Document 1, a fixing belt is provided so as to span between a fixing roller and a tension roller, and a tension applying member including a tension spring is attached to one end of a holding member that holds the tension roller. In the fixing device provided with a heating member inside the fixing belt, the holding member is rotated about a fulcrum provided at one point of the holding member, and the tension is applied. It has been proposed to move the tension roller so that the fixing belt approaches the heating member when the applying member moves in the direction of applying tension.

  However, in the one shown in Patent Document 1, a mechanism for rotating a holding member that applies tension to the tension roller is required, and a tension spring is used as the tension applying member, and the tension roller is moved by the tension spring. Since the fixing device is pulled, the size of the fixing device is increased, and further, since a fixing roller is used, there is a problem that heat loss during heat fixing increases.

  In recent years, in order to save energy, for example, as shown in Patent Document 2, in place of the fixing roller, a heat-resistant elastic member is formed in a portion where the pressure roller is pressed and a nip is formed. A non-rotating fixing fixing member provided with a belt is used, and a fixing belt is stretched between the fixing fixing member and a heating roller so that tension is applied to the fixing belt.

  However, in the one shown in Patent Document 2, a pressing member such as a spring is provided on the inner peripheral side of the fixing belt, and the heating roller is urged in a direction away from the fixing fixing member by the pressing member. In order to arrange a pressing member such as a spring on the inner peripheral side of the belt, it is necessary to pay attention to the arrangement of the peripheral members. For example, the distance from the heating roller is increased so that the fixing fixing member does not hit the spring. It will be necessary. As a result, it is necessary to increase the diameter of the fixing belt in the fixing device, which increases the size of the fixing device and increases the heat loss during heat fixing.

JP, 2014-66902, A. JP 2008-46663 A.

  The present invention solves the above-described problems in a fixing device that fixes a toner image transferred to a recording medium onto the recording medium in an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a combination of these. It is to be an issue.

  In the present invention, the fixing belt is wound around the heating side member and the nip forming member, and the pressure is rotationally driven by being pressed against the nip forming member so as to sandwich the fixing belt. And the fixing belt is pressed against the pressure member by the nip forming member and rotated, so that the fixing belt and the pressure member are pressed against each other. In the fixing device that fixes the toner image to the recording medium in the nip portion, it is an object to reduce the size of the fixing device and reduce heat loss at the time of heat-fixing to save energy.

  In the fixing device according to the present invention, in order to solve the above-described problems, the fixing belt wound around the heating side member and the nip forming member, and the fixing belt attached to the nip forming member. A pressure member that is rotationally driven by being pressed so as to be sandwiched, and in a state in which tension is applied to the fixing belt by a pressing member, the fixing belt is pressed against the pressure member by the nip forming member, and is rotationally driven. In the fixing device for fixing the toner image to the recording medium at the nip portion where the fixing belt and the pressure member are pressed, in a direction inclined with respect to a line connecting the center of the heating side member and the center of the nip portion. The heating member is biased in the direction away from the nip portion by the pressing member, and at least a part of the pressing member is moved outside the fixing belt. And so as to location.

  Here, as in the fixing device, the heating side member is moved away from the nip portion by the pressing member in a direction inclined with respect to a line connecting the center of the heating side member and the center of the nip portion. When the biasing member is biased and at least a part of the pressing member is disposed outside the fixing belt, the pressing member is provided in the fixing belt so as to be along a line connecting the center of the heating side member and the center of the nip portion. Compared with the case where tension is applied to the fixing belt, the diameter of the fixing belt can be reduced and the fixing device can be downsized.

  In the fixing device, when the nip forming member is provided so as to press the fixing belt against the pressing member as described above, the supporting member is provided so as to face the pressing member via the fixing belt. Is preferably provided in the width direction of the fixing belt, and the nip forming member is fixedly attached to the attachment surface of the support member facing the pressure member. In this way, when the nip forming member is fixed and attached to the mounting surface of the support member, the nip forming member is made smaller than when a fixing roller as disclosed in Patent Document 2 is used as the nip forming member. However, it is easy to secure a sufficient nip portion, and the fixing belt can be reduced in size by reducing the diameter of the fixing belt.

  In the fixing device, the heating side member is preferably provided at a position upstream of the center position of the nip portion in the moving direction of the fixing belt. As described above, when the heating side member is provided at a position upstream of the center position of the nip portion in the fixing belt movement direction, the length of the fixing belt in the portion heated by the heating side member and guided to the nip portion is shortened. The heat of the fixing belt guided between the nip forming member and the pressure member can be prevented from being reduced, and energy saving can be achieved.

  In the fixing device, it is preferable that the pressing member is provided downstream of the nip portion in the moving direction of the fixing belt. Thus, when the pressing member is provided downstream of the nip portion in the fixing belt moving direction, the heating side member is provided at the upstream side of the fixing belt moving direction from the center position of the nip portion as described above. The pressing member does not get in the way, and the heating side member can be appropriately arranged at a position upstream of the center position of the nip portion in the moving direction of the fixing belt.

  In the fixing device, when attaching the end portions of the support member extending in the width direction of the fixing belt to the side plates on both sides of the fixing device, the moving direction of the fixing belt on the mounting surface of the support member An extension portion extending in a direction intersecting the moving direction of the fixing belt toward the heating side member is provided on the upstream side and the downstream side of the support member, and the extension portion extends at the end of the support member. It is preferable to make the length shorter than the extension length in the extension part other than the end part. In this case, the support member can be disposed near the heating side member, the diameter of the fixing belt can be reduced, the fixing device can be downsized, and heat loss at the time of heat fixing can be reduced. Can do.

  Further, in the fixing device, when the support member and the heating side member are provided, a support member for attaching an end portion of the support member that extends in the width direction of the fixing belt to the side plates on both sides of the fixing device. An attachment part and the heating side member attachment part which attaches the edge part of the said heating side member can be provided.

  Here, the support member is formed in a cross-sectional groove shape, and the fixing surface to which the nip forming member is fixed is attached to the fixing belt in the moving direction upstream side and the moving direction downstream side toward the heating side member. An upstream extension portion and a downstream extension portion that extend in the opposite direction to the nip portion are provided, and the length of the upstream extension portion is shorter than the length of the downstream extension portion. be able to.

  In the fixing device, the heating side member mounting portions are provided on the side plates on both sides of the fixing device, and the heating side member attached to the heating side member mounting portion is biased in the direction away from the nip portion. A heat insulating bush is provided on the outer periphery of the end portion of the member, a bearing member that rotatably holds the end portion of the heating side member is provided in the heating side member mounting portion, and the heating side member is provided by the pressing member via the bearing member. It can be urged away from the nip portion. As described above, when the heat insulating bush is provided on the outer periphery of the end portion of the heating side member, the heat of the heating side member is prevented from being transmitted to the bearing member and released, and is heated by the pressing member via the bearing member. By urging the side member in the direction away from the nip portion, it is not necessary to provide the pressing member in the fixing belt, and the fixing belt can be reduced in size by reducing the diameter of the fixing belt.

  In the fixing device, the nip forming member is made of a heat-resistant resin such as liquid crystal polymer (LCP), and the corner on the upstream side in the moving direction of the fixing belt in the nip forming member around which the fixing belt is wound. R shape is preferable. As described above, when the corner on the upstream side in the moving direction of the fixing belt in the nip forming member around which the fixing belt is wound has an R shape, the resistance of the fixing belt guided from the nip forming member to the nip is reduced, and the fixing belt It can be driven to rotate stably.

  In the fixing device, the support member includes a guide member that guides the fixing belt to the heating side member in a downstream portion of the support member on the downstream side of the nip forming member in the moving direction of the fixing belt. The corner of the guide member around which the fixing belt is wound is preferably formed in an R shape. In this way, the fixing belt is guided from the nip forming member to the guide member so as not to contact the support member, and the resistance of the fixing belt moving through the guide member is reduced, so that the fixing belt is stabilized. And is driven to rotate.

  In the image forming apparatus of the present invention, the fixing device as described above is used as a fixing device for fixing the toner image formed on the recording medium to the recording medium.

  In the fixing device of the present invention, the heating member is separated from the nip portion by the pressing member in a direction inclined with respect to a line connecting the center of the heating member and the center of the nip portion as described above. Since at least a part of the pressing member is disposed outside the fixing belt, the pressing member is provided in the fixing belt, and is along a line connecting the center of the heating side member and the center of the nip portion. Thus, the diameter of the fixing belt can be reduced and the fixing device can be downsized as compared with the case where tension is applied to the fixing belt.

  As a result, in the image forming apparatus using the fixing device as described above, it is possible to reduce the size of the fixing device, reduce heat loss at the time of heat fixing, and save energy.

1 is a schematic explanatory diagram illustrating an example of an image forming apparatus using a fixing device according to a first exemplary embodiment of the present invention. FIG. 2 is a schematic explanatory view showing a fixing device according to the first embodiment. In the fixing device according to the first embodiment, a support member for fixing and arranging a nip forming member is shown, (A) is a schematic perspective view, and (B) is a schematic side view. FIG. 2 is a schematic explanatory view showing a state in which a fixing belt wound around a heating roller and a nip forming member is removed in the fixing device according to the first embodiment. FIG. 3 is a schematic explanatory view showing a state in which the fixing belt is wound around a heating roller and a nip forming member in the fixing device according to the first embodiment. FIG. 6 is a schematic explanatory view showing a fixing device according to Embodiment 2 of the present invention.

  Next, a fixing device according to an embodiment of the present invention and an image forming apparatus using the fixing device will be specifically described with reference to the accompanying drawings. The fixing device and the image forming apparatus according to the present invention are not limited to those shown in the following embodiments, and can be appropriately modified and implemented without departing from the scope of the invention.

(Embodiment 1)
FIG. 1 illustrates an image forming apparatus that uses the fixing device according to the first exemplary embodiment.

  In the image forming apparatus 1, as shown in FIG. 1, four imaging cartridges 10A to 10D are mounted therein.

  Here, in each of the imaging cartridges 10A to 10D, the photosensitive member 11, the charging device 12 for charging the surface of the photosensitive member 11, and the surface of the charged photosensitive member 11 are exposed according to image information. A latent image forming device 13 for forming an electrostatic latent image on the surface of the photoconductor 11, a developing device 14 for supplying toner to the electrostatic latent image formed on the surface of the photoconductor 11 to form a toner image, A first cleaning device 15 that removes toner remaining after the toner image formed on the surface of the photoconductor 11 is transferred to the intermediate transfer belt 21 from the surface of the photoconductor 11 is provided.

  In the developing devices 14 in the imaging cartridges 10A to 10D, toners of different colors are accommodated, and black, yellow, magenta, and cyan toners are accommodated.

  In the image forming apparatus 1, in each of the imaging cartridges 10 </ b> A to 10 </ b> D, the surface of the photoreceptor 11 is charged by the charging device 12, and the surface of each photoreceptor 11 charged in this way is latent. The image forming apparatus 13 performs exposure according to the image information, and forms an electrostatic latent image according to the image information on the surface of each photoconductor 11. A toner of each color is supplied from the developing device 14 to the latent image, and a toner image of each color is formed on the surface of each photoconductor 11.

  Next, the toner image of each color formed on the surface of each photoconductor 11 in each of the imaging cartridges 10A to 10D in this way is stretched between the driving roller 20a and the rotating roller 20b and is driven to rotate. The toner image is sequentially transferred onto the intermediate transfer belt 21 by the primary transfer roller 22 to form a synthesized toner image on the intermediate transfer belt 21, and the toner image thus formed is transferred to the secondary transfer roller 21 by the intermediate transfer belt 21. The toner remaining on the surface of each photoconductor 11 after transfer is removed from the surface of each photoconductor 11 by the corresponding first cleaning device 15.

  On the other hand, the recording medium S accommodated in the image forming apparatus 1 is fed by the paper feed roller 24 and guided to the timing roller 25, and the timing roller 25 feeds the recording medium S to the intermediate transfer belt at an appropriate timing. 21 and the secondary transfer roller 23 are guided.

  Then, the toner image formed on the intermediate transfer belt 21 is transferred to the recording medium S by the secondary transfer roller 23, but remains on the intermediate transfer belt 21 without being transferred to the recording medium S. The toner is removed from the intermediate transfer belt 21 by the second cleaning device 26.

  Next, the recording medium S to which the toner image is transferred in this way is guided to the fixing device 30, and the unfixed toner image transferred to the recording medium S is fixed on the recording medium S by the fixing device 30, and then the toner The recording medium S on which the image is fixed is separated from the fixing device 30 and guided to the paper discharge roller 27, and the recording medium S on which the toner image is fixed is discharged by the paper discharge roller 27.

  Here, in the fixing device 30 according to the first exemplary embodiment, as illustrated in FIGS. 1 and 2, a heating roller 31 in which a heating device 31 a such as a halogen lamp is provided is used as the heating side member 31. The fixing belt 33 that has become endless by the heating roller 31 is heated.

  The endless fixing belt 33 is bridged between the heating roller 31 and the nip forming member 32 fixedly attached to the attachment surface 35a of the support member 35 formed in a groove shape. The pressure member 34 formed of a pressure roller 34 that is rotationally driven so as to sandwich the fixing belt 33 is pressed against the nip forming member 32, and tension is applied to the fixing belt 33. In the applied state, the fixing belt 33 is rotated together with the pressure roller 34, and the toner image t at the nip portion where the heated fixing belt 33 is pressed against the pressure roller 34 by the nip forming member 32. Is fixed to the recording medium S.

  In the fixing device 30 according to the first exemplary embodiment, the heating roller 31 is disposed upstream of the center position of the nip portion where the fixing belt 33 is pressed against the pressure roller 34 in the moving direction of the fixing belt 33 in the nip portion. As shown in FIG. 2 and the like, the end portion of the heating roller 31 is rotatably attached to the heating side member attaching portion 301 provided on the side plate 300 of the fixing device 30 so as to be positioned on the side portion. I have to.

  Here, as described above, when the heating roller 31 is positioned at a portion of the nip portion upstream of the moving direction of the fixing belt 33 with respect to the center position of the nip portion where the fixing belt 33 is pressed against the pressure roller 34, It is possible to prevent the heat of the fixing belt 33 from being lowered by shortening the moving distance of the fixing belt 33 until it is heated by the heating roller 31 and guided to the nip portion.

  Further, in this embodiment, as described above, when the end portion of the heating roller 31 is rotatably attached to the heating side member mounting portion 301 provided on the side plate 300 of the fixing device 30, the outer periphery of the end portion of the heating roller 31. In addition, a heat insulating bush 31b is disposed, and a bearing member 31c including a bearing that rotatably holds an end portion of the heating roller 31 provided with the heat insulating bush 31b is provided in the heating side member mounting portion 301.

  Further, in the fixing device 30 of the first embodiment, when the heating roller 31 is urged by the pressing member 37 in the direction away from the nip portion, the distal end portion of the compression coil spring 37a is used as the pressing member 37. The mounting member 37b attached to the bearing member 31c is used, and the pressing member 37 is disposed in the pressing member mounting portion 302 provided to communicate with the heating side member mounting portion 301 in the side plate 300. The heating roller 31 is biased in the direction away from the nip portion via the bearing member 31c by the mounting member 37b provided at the tip of the compression coil spring 37a. In addition, in order to urge the heating roller 31 in the direction away from the nip portion by the pressing member 37 in this way, although not shown, the heating side member mounting portion 301 is urged toward the heating roller 31. The length of is formed so as to be long.

  Further, as described above, the heating roller 31 is positioned at a portion upstream of the center of the nip portion where the fixing belt 33 is pressed against the pressure roller 34 in the moving direction of the fixing belt 33 in the nip portion. When the heating roller 31 is urged by the pressing member 37 in the direction away from the nip portion, the center position of the nip portion and the heating roller 31 are directed from the position above the heating roller 31 toward the downstream side in the moving direction of the fixing belt 33. The heating roller 31 is pressed by the pressing member 37 so as to be inclined obliquely with respect to the line connecting the centers.

  In the fixing device 30 of the first embodiment, the nip forming member 32 is provided when the nip forming member 32 is provided on the mounting surface 35a on the opposite side of the heating roller 31 of the support member 35 formed in the groove shape as described above. As a material, a heat-resistant resin such as LCP (liquid crystal polymer) or PPS (polyphenylene sulfide) is used, and the surface of the nip forming member 32 that contacts the fixing belt 33 is covered with a sliding sheet 32a. In this nip forming member 32 around which the fixing belt 33 is wound, the corner on the upstream side in the moving direction of the fixing belt 33 is formed in an R shape, and the load applied to the fixing belt 33 is reduced when the fixing belt 33 is rotationally driven. The fixing belt 33 is driven to rotate smoothly.

  In the fixing device 30 according to the first embodiment, the support member 35 formed in the groove shape as described above has an upstream side in the moving direction of the fixing belt 33 on the attachment surface 35a to which the nip forming member 32 is attached. The upstream extending portion 35b and the downstream extending portion 35c are extended in the direction intersecting the moving direction of the fixing belt 33 toward the heating roller 31 at the portion downstream of the moving direction, The extension length xa of the upstream extension part 35b is shorter than the extension length xb of the downstream extension part 35c. In this case, when the heating roller 31 is provided at a position on the upstream side in the moving direction of the fixing belt 33 in the nip portion with respect to the center position of the nip portion as described above, the heating roller 31 extends on the upstream side. The heat from the heating roller 31 is prevented from flowing to the support member 35 through the upstream extending portion 35b and released without being too close to the protruding portion 35b, and heat loss can be reduced.

  In the fixing device 30 according to the first embodiment, the guide that guides the fixing belt 33 that has passed through the nip forming member 32 to the heating roller 31 on the downstream-side extending portion 35 c of the support member 35. The member 38 is provided, and the corner portion of the guide member 38 around which the fixing belt 33 is wound is formed in an R shape, and when the fixing belt 33 is rotationally driven, the load applied to the fixing belt 33 is reduced so that the fixing belt 33 is smoothly It is designed to be rotated. The guide member 38 is made of a heat-resistant resin such as LCP (liquid crystal polymer) or PPS (polyphenylene sulfide), like the nip forming member 32 described above.

  Further, in the fixing device 30 of the first embodiment, the lubricant is held on the inner peripheral surface of the fixing belt 33, and the lubricant is appropriately held on the sliding sheet 32a in the nip forming member 32. Thus, the frictional resistance between the fixing belt 33 and the nip forming member 32 is reduced, and a lubricant regulating portion 38a is provided on the upper surface portion of the guide member 38 along the longitudinal direction thereof. The agent regulating portion 38a regulates and stabilizes the amount of lubricant adhering to the inner peripheral surface of the fixing belt 33.

  In the fixing device 30 according to the first embodiment, the end portion of the support member 35 as described above is attached to a support member attachment portion 303 provided on the side plate 300 of the fixing device 30.

  Here, in the fixing device 30 of the first embodiment, as the support member 35, as shown in FIGS. 3A and 3B, the upstream of the upstream end of the support member 35 at both ends. Notches 35b1 and 35c1 are provided in the side extension part 35b and the downstream extension part 35c, respectively, and the upstream extension part 35b and the downstream extension part 35c are extended from the attachment surfaces 35a at both ends. And a recess 35a1 is provided on the mounting surface 35a.

  And as shown in FIG. 4, in the edge part of the both sides in the support member 35, the edge part of the upstream extension part 35b and the downstream extension part 35c which the length extended from the attachment surface 35a became short was used. Each of the fixing members 30 protrudes from the side plate 300 through the holes 303a and 303b provided in the support member attachment portion 303, and the recess 35a1 provided in the attachment surface 35a is interposed between the holes 303a and 303b. I try to pinch it.

  Here, as described above, notches 35b1 and 35c1 are provided in the upstream extending portion 35b and the downstream extending portion 35c, respectively, at the ends on both sides of the support member 35, and the upstream extending portion 35b and the downstream extending portion are provided. If the length extended from the attachment surface 35a in the edge part of both sides to the protrusion part 35c is shortened, the magnitude | size of each hole 303a, 303b provided in the support member attachment part 303 can be made small.

  As a result, in the side plate 300 of the fixing device 30, it is possible to increase the distance between the heating side member attachment portion 301 to which the end portion of the heating roller 31 is attached and the support member attachment portion 303 to which the end portion of the support member 35 is attached. The pressing member mounting portion 302 to which the pressing member 37 is attached can be provided at an appropriate position on the side plate 300 of the fixing device 30, and the fixing device 30 can be downsized.

  In the fixing device 30 of the first embodiment, the heating roller 31 is used as the heating side member 31, but the heating side member 31 can heat the fixing belt 33. There is no particular limitation, and although not shown, it is also possible to use an induction heating heating element using an exciting coil.

(Embodiment 2)
In the fixing device 30B according to the second embodiment, as illustrated in FIG. 6, the tension roller 311 and the heater unit 312 are used as the heating side member 310 while the nip forming member 320 is used, as shown in Patent Document 1 described above. As the fixing roller 320 is rotatable, the fixing belt 330 is wound around the tension roller 311 and the fixing roller 320, and the tension roller 311 is pressed by a pressing spring (pressing member) 370. The tension is applied to the fixing belt 330 by urging the fixing belt 320 away from the fixing roller 320 via a holding member 360.

  Here, in the second embodiment, a holding member 360 that rotates around a fulcrum 361 on one end side is provided outside the fixing belt 330, and the tension roller 311 is held by the holding member 360. On the other hand, one end of a pressing spring 370 provided on the fixing roller 320 side is attached to the other end side of the holding member 360, and the tension roller 311 is moved from the fixing roller 320 via the holding member 360 by the pressing spring 370. The urging force is applied in the direction away from the fixing belt 330 so that tension is applied to the fixing belt 330.

  In the second embodiment, the heater unit 312 is brought into contact with the inner peripheral surface of the fixing belt 330 on the way from the tension roller 311 to the fixing roller 320, and the fixing belt 330 is heated by the heater unit 312. I try to let them.

  In the second embodiment, the pressure member 340 includes a pressure roller 340 that is rotationally driven so that the fixing belt 330 is sandwiched between the fixing roller 320 at a position facing the fixing roller 320. , The fixing belt 330 is rotated together with the pressure roller 340, and the toner image t is recorded at the nip portion where the fixing belt 330 heated as described above is pressed against the pressure roller 340 by the fixing roller 320. The image is fixed on the medium S.

  Here, in the fixing device 30B of the second embodiment, as described above, the holding member 360 provided outside the fixing belt 330 is pressed by the pressing spring 370 provided on the fixing roller 320 side, and the tension roller Since 311 is urged away from the fixing roller 320, the fixing device 300 can be made smaller than that of the above-mentioned Patent Document 1 using a tension spring as a tension applying member. Become.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10A-10D Imaging cartridge 11 Photoconductor 12 Charging apparatus 13 Latent image forming apparatus 14 Developing apparatus 15 1st cleaning apparatus 20a Driving roller 20b Rotating roller 21 Intermediate transfer belt 22 Primary transfer roller 23 Secondary transfer roller 24 Paper feed Roller 25 Timing roller 26 Second cleaning device 27 Paper discharge roller 30, 30B Fixing device 31 Heating roller (heating side member)
31a Heating device 31b Thermal insulation bush 31c Bearing member 32 Nip forming member 32a Sliding sheet 33 Fixing belt 34 Pressure roller (pressure member)
35 support member 35a attachment surface 35a1 recess 35b upstream extension part 35b1 notch 35c downstream extension part 35c1 notch 37 pressing member 37a compression coil spring 37b attachment member 38 guide member 38a lubricant regulating part 300 side plate 301 heating side member Attachment portion 302 Press member attachment portion 303 Support member attachment portion 303a, 303b Hole 310 Heating side member 311 Tension roller 312 Heater unit 320 Fixing roller (nip forming member)
330 fixing belt 340 pressure roller (pressure member)
360 holding member 361 fulcrum 370 pressing spring (pressing member)
S recording medium t toner image

Claims (11)

  A fixing belt that is wound around the heating side member and the nip forming member, and a pressing member that is driven to rotate so as to sandwich the fixing belt with the nip forming member. In a state where tension is applied to the fixing belt, the fixing belt is pressed against the pressure member by the nip forming member and rotated to drive the toner image at the nip portion where the fixing belt and the pressure member are pressed. In a fixing device for fixing to a recording medium, the pressing member is used to attach the heating side member away from the nip portion in a direction inclined with respect to a line connecting the center of the heating side member and the center of the nip portion. And a fixing device in which at least a part of the pressing member is disposed outside the fixing belt.   The fixing device according to claim 1, wherein a support member is provided in a width direction of the fixing belt so as to be opposed to the pressure member via the fixing belt, and an attachment surface of the support member facing the pressure member is provided. A fixing device, wherein the nip forming member is fixed and attached.   The fixing device according to claim 2, wherein the heating side member is provided at a position upstream of the center position of the nip portion in the moving direction of the fixing belt.   The fixing device according to claim 2, wherein the pressing member is provided downstream of the nip portion in the moving direction of the fixing belt.   5. The fixing device according to claim 2, wherein the support member is attached to the side plates on both sides of the fixing device with end portions extending in the width direction of the fixing belt of the support member. 6. An extending portion extending in a direction intersecting with the moving direction of the fixing belt toward the heating side member is provided on the upstream side and the downstream side in the moving direction of the fixing belt on the mounting surface of the fixing belt; The fixing device according to claim 1, wherein an extension length of the extension portion is shorter than an extension length of the extension portion other than the end portion.   6. The fixing device according to claim 2, wherein a supporting member mounting portion that attaches end portions of the supporting member extending in the width direction of the fixing belt to side plates on both sides of the fixing device. And a heating side member attaching portion for attaching an end portion of the heating side member.   7. The fixing device according to claim 2, wherein the support member is formed in a cross-sectional groove shape, and the fixing belt is fixedly attached to the attachment surface on the upstream side in the moving direction of the fixing belt. An upstream extension part and a downstream extension part extending in the direction opposite to the nip part toward the heating side member are provided on the downstream side in the movement direction, and the length of the upstream extension part is A fixing device characterized in that the fixing device is shorter than the length of the downstream extending portion.   8. The fixing device according to claim 6, wherein a heat insulating bush is provided on an outer periphery of an end portion of the heating side member, and a bearing member that rotatably holds the end portion of the heating side member is provided. A fixing device provided at the heating side member mounting portion and biasing the heating side member in a direction away from the nip portion by a pressing member via the bearing member.   9. The fixing device according to claim 2, wherein the nip forming member is made of a heat-resistant resin, and a corner of the nip forming member around which the fixing belt is wound is formed in an R shape. A fixing device characterized by the above.   10. The fixing device according to claim 2, wherein a guide member that guides the fixing belt to the heating side member is provided at a portion of the support member that is downstream of the nip forming member in the moving direction of the fixing belt. A fixing device in which a corner portion of a guide member around which a fixing belt is wound has an R shape. An image forming apparatus comprising a fixing device for fixing a toner image formed on a recording medium to the recording medium, wherein the fixing device according to any one of claims 1 to 10 is used. Forming equipment.

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