JP6021758B2 - Fixing apparatus and image forming apparatus having the same - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus including the fixing device, and more particularly to a fixing device that restricts a belt member from shifting in the axial direction of a roller and an image forming apparatus including the fixing device.

  The image forming apparatus transfers a toner image formed on an image carrier such as a photosensitive drum to a recording medium, conveys the recording medium carrying the toner image toward a fixing device, and heat and pressure are applied to the fixing device. In addition, the unfixed toner image on the recording medium is fixed on the recording medium. The fixing device includes a belt member that is rotatably stretched between a fixing roller and a heat roller, and a pressure roller that is pressed against the belt member, and the recording medium is disposed between the belt member and the pressure roller. There is a belt fixing method in which a toner image is fixed on a recording medium while passing through the fixing nip portion.

  In a belt fixing type fixing device, the belt member may move in the axial direction of the roller and shift (meander). The deviation (meandering) of the belt member is most likely to occur when the belt member passes through the fixing nip portion where the load is applied to the belt member, and also when the parallelism between the plurality of rollers in the belt inscribed in the belt member is low. Occur. If the deviation of the belt member occurs, it may cause a fixing failure such as a displacement of the toner image on the recording medium. If the deviation of the belt member continues, the end of the belt member in the width direction may be damaged. was there.

  Therefore, a technique for suppressing the deviation of the belt member has been conventionally known. For example, a conventional fixing device includes a belt member, a fixing roller and a heat roller that are in contact with the inner peripheral surface of the belt member, and a pressure roller that is pressed against the fixing roller via the belt member. A pair of restricting members that restrict the belt member from shifting in the axial direction of the heat roller are provided at both ends of the direction. This fixing device is configured to return (move) the belt member to the inner side in the axial direction of the heat roller by the regulating member when the belt member is shifted in the axial direction of the heat roller.

  A fixing device that suppresses the deviation of the belt member by providing a guide groove on the outer peripheral surface of the plurality of belt inner rollers and providing a guided portion that engages with the guide groove on the inner peripheral surface of the belt member. It is disclosed in Patent Documents 1 and 2.

JP 2000-001237 A JP 2002-145429 A

  However, in the conventional fixing device, when the belt member is displaced, the belt member is moved to a predetermined position by one restriction member at a time in order to eliminate the displacement of the belt member. For this reason, since the load applied to the belt member becomes large at the contact portion between the regulating member and the belt member, the belt member may be damaged.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fixing device capable of suppressing breakage and deviation of the belt member and an image forming apparatus including the same. Is to provide.

  In order to achieve the above object, a fixing device of the present invention includes an endless belt member heated by a heating member, two or more in-belt rollers that are in contact with the inner peripheral surface of the belt member, and a belt member. And a rotatable pressure roller that is disposed opposite to the outer peripheral surface of the belt and pressed against one of the inner rollers of the belt via the belt member, and records on a fixing nip formed by the belt member and the pressure roller. A fixing device that inserts a medium and fixes an unfixed toner image on a recording medium. The belt member is offset in the axial direction of the belt inner roller at both ends in the axial direction of the two belt inner rollers. A pair of first restricting members and a pair of second restricting members are provided, respectively, and each of the first restricting member and the second restricting member moves the belt member inward of the belt inner roller in the axial direction. The regulation surface includes a first position located on the inner side in the axial direction of the inner roller of the belt, and a second position located on the outer side in the axial direction of the inner roller and larger in diameter than the first position. The distance between the first positions of the pair of first restricting members is x1, the distance between the second positions of the pair of first restricting members is x1max, and the first positions of the pair of second restricting members are When the distance between the first restriction member and the second restriction member is x2, the first restriction member and the second restriction member are disposed so as to satisfy the relationship of x1 <x2 <x1max.

  According to the present invention, the pair of first restricting members and the pair of second restricting members for restricting the belt members from being offset in the axial direction of the in-belt rollers are respectively provided at both axial ends of the two in-belt rollers. The distance between the first positions of the pair of first restricting members is x1, the distance between the second positions of the pair of first restricting members is x1max, and the first of the pair of second restricting members is provided. When the distance between the positions is x2, the first restricting member and the second restricting member are arranged so as to satisfy the relationship x1 <x2 <x1max. As a result, when the belt member is displaced, the side end portion of the belt member is returned (moved) to the first position of the second restriction member by the second restriction member, and then the first restriction member is moved by the first restriction member. Is returned (moved) to the first position. That is, the belt member can be gradually returned (moved) to a predetermined position. For this reason, since it can suppress that the load concerning a belt member becomes large in the contact part of a control member and a belt member, it can suppress that a belt member is damaged.

1 is a cross-sectional view schematically illustrating an overall structure of an image forming apparatus including a fixing device according to a first embodiment of the present invention. 1 is a cross-sectional view illustrating a structure of a fixing device according to a first embodiment of the present invention. FIG. 3 is a plan view showing a structure around a first restriction member and a second restriction member of the fixing device according to the first embodiment of the present invention. It is sectional drawing which showed the structure of the fixing device of 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
An image forming apparatus 1 including a fixing device 5 according to a first embodiment of the present invention will be described with reference to FIGS. The image forming apparatus 1 is a tandem type color printer, and includes a paper feeding unit 10 that stores paper P as a recording medium, four image forming units 29a to 29d arranged above the paper feeding unit 10, and an image. Exposed units 33a to 33d disposed above the forming units 29a to 29d, the fixing device 5 disposed to the left of the image forming units 29a to 29d, and the right side of the paper feeding unit 10. A sheet conveyance path 20 and a discharge unit 50 that discharges the sheet P at the top of the image forming apparatus 1 are provided.

  The paper feeding unit 10 is disposed below the image forming apparatus 1, and the paper feeding unit 10 is provided with a paper feeding cassette 13 that accommodates the paper P and is detachably attached to the image forming apparatus 1. A paper transport path 20 is disposed on the right side of the paper feed unit 10, and the paper P placed in the paper feed cassette 13 is sent out to the paper transport path 20 one by one by the feed roller 21. The manual feed tray 23 supplies paper P or the like of a size that is not placed on the paper supply unit 10, and includes a feed roller 22. The paper P is fed one by one to the paper transport path 20 by the feed roller 22, The fed paper P is conveyed toward the image forming units 29a to 29d.

  The image forming units 29a to 29d are arranged so as to face the sheet conveying belt 38 for each color of cyan, magenta, yellow, and black in order from the upstream side in the sheet conveying direction (the right side in FIG. 1). Each of the image forming units 29a to 29d includes photoreceptors 31a to 31d, and around the photoreceptors 31a to 31d, chargers 32a to 32d, developing devices 34a to 34d, transfer rollers 35a to 35d, and cleaners. 36a to 36d are disposed.

  The photoconductors 31a to 31d are amorphous silicon photoconductors as photosensitive materials for forming the photosensitive layer, and are arranged corresponding to each color of cyan, magenta, yellow, and black. The photosensitive layer may be an organic photoreceptor (OPC photoreceptor). The developing devices 34a to 34d are disposed on the right side of the photoconductors 31a to 31d, have a developing roller, and supply toner to the photoconductors 31a to 31d. The chargers 32a to 32d are disposed upstream of the developing devices 34a to 34d in the rotation direction of the photoconductors 31a to 31d, and uniformly charge the surfaces of the photoconductors 31a to 31d.

  The exposure units 33a to 33d are arranged on the surfaces of the photoreceptors 31a to 31d from between the chargers 32a to 32d and the developing devices 34a to 34d based on image data input to an image input unit (not shown) from a personal computer or the like. Irradiate with laser light. Electrostatic latent images are formed on the surfaces of the photoreceptors 31a to 31d by the irradiated laser light, and the electrostatic latent images are developed by the developing devices 34a to 34d.

  The sheet transport belt 38 is an endless belt stretched between the driving roller 40 and the driven roller 41, and is a belt that carries and transports the sheet P between the photoreceptors 31a to 31d and the transfer rollers 35a to 35d. Form a travel path. The transfer rollers 35a to 35d are brought into pressure contact with the photoreceptors 31a to 31d with the paper transport belt 38 interposed therebetween, thereby forming a transfer nip portion. The paper P transported from the paper transport path 20 is carried on the paper transport belt 38, and the toner images of the photoconductors 31 a to 31 d are sequentially transferred onto the paper P in each transfer nip portion by the rotation of the paper transport belt 38, and are transferred to the paper P. Is superimposed with toner images of four colors of cyan, magenta, yellow and black.

  The toner tanks 39a to 39d supply toner to the developing devices 34a to 34d, and are disposed above the image forming units 29a to 29d, and store toners of cyan, magenta, yellow, and black.

  The fixing device 5 is disposed on the downstream side of the paper conveyance belt 38, and heats and presses the paper P on which the toner image is transferred in the image forming units 29a to 29d to melt and fix the toner image on the paper P. The paper P that has passed through the fixing device 5 is discharged from the paper transport path 15 to the discharge unit 50.

  As shown in FIG. 2, the fixing device 5 employs a fixing method that is heated by electromagnetic induction, and includes a belt member 61, two rotatable belt inner rollers 62 that are in contact with the inner peripheral surface of the belt member 61, and A rotatable pressure roller 63 disposed opposite to the outer peripheral surface of the belt member 61 and pressed against the in-belt roller 62 via the belt member 61; an induction heating unit 64 that is a heating member for heating the belt member 61; A temperature detection unit (not shown) for detecting the temperature of the surface of the belt member 61, a control unit (not shown) connected to the temperature detection unit and the induction heating unit 64, and a high-frequency current in the coil of the induction heating unit 64 And a power source (not shown).

  The belt member 61 is an endless heat-resistant belt, and in order from the inner peripheral side, for example, an induction heating layer 61a made of electroformed nickel having a thickness of about 30 to 50 μm, and an elastic made of silicone rubber or the like having a thickness of about 200 to 500 μm. A layer 61b and a release layer 61c made of, for example, a fluororesin (for example, FPA) having a thickness of 30 μm and the like, which improve releasability when an unfixed toner image is melted and fixed at the fixing nip portion N, are laminated. Is done.

  The in-belt roller 62 includes a fixing roller 65 that is pressed against the pressure roller 63 via the belt member 61, and a heat roller 66 that is disposed to face the fixing roller 65. For example, the fixing roller 65 has an outer diameter of 40 mm, and has an elastic layer 65b made of silicone rubber having a thickness of 5 to 10 mm on the outer peripheral surface of a cylindrical cored bar 65a such as stainless steel or aluminum. Is opposed to the inner peripheral surface of the belt member 61. For example, the heat roller 66 is set to an outer diameter of 30 mm, and a release layer (for example, a PFA layer) having a thickness of 0.2 to 1.0 mm on the outer peripheral surface of an iron base material 66a having a thickness of 0.3 to 0.5 mm. 66b. By forming the heat roller 66 using iron which is a ferromagnetic member, it is possible to improve the heat generation efficiency.

  The pressure roller 63 includes a cylindrical cored bar 63a, an elastic layer 63b formed on the outer peripheral surface of the cored bar 63a, and a release layer 63c that covers the surface of the elastic layer 63b. For example, the pressure roller 63 is set to an outer diameter of 35 mm, has an elastic layer 63b made of silicone rubber having a thickness of 2 to 5 mm on the outer peripheral surface of a core metal 63a such as stainless steel or aluminum, and the outer periphery of the elastic layer 63b. On the surface, there is a release layer 63c made of fluororesin (for example, FPA) having a thickness of 50 μm. The pressure roller 63 is rotated by a driving source such as a motor (not shown), and the belt member 61, the fixing roller 65, and the heat roller 66 are driven to rotate by the rotation of the pressure roller 63. A fixing nip portion N is formed at a portion where the pressure roller 63 and the belt member 61 are pressed against each other. In the fixing nip portion N, an unfixed toner image on the paper P sent from the paper transport belt 38 is heated and pressed. The toner image is fixed on the paper P.

  The induction heating unit 64 includes a coil 64a, a bobbin 64b, and a magnetic core 64c, and causes the belt member 61 to generate heat by electromagnetic induction. The induction heating unit 64 extends in the longitudinal direction (the front and back direction of the paper surface of FIG. 2) and is disposed so as to face the belt member 61 so as to surround substantially half of the outer periphery of the heat roller 66.

  The coil 64a is attached to the bobbin 64b by being wound a plurality of times (for example, 9 turns) in a loop shape along the width direction of the belt member 61 (the front and back direction in FIG. 2). The coil 64a is connected to a power source (not shown) and generates an alternating magnetic flux by a high-frequency current supplied from the power source. The magnetic flux from the coil 64 a passes through the magnetic core 64 c, is guided in a direction parallel to the paper surface of FIG. 2, and passes along the induction heating layer 61 a of the belt member 61. An eddy current is generated in the induction heating layer 61a due to a change in the alternating strength of the magnetic flux passing through the induction heating layer 61a. When an eddy current flows through the induction heating layer 61a, Joule heat is generated by the electrical resistance of the induction heating layer 61a, and the belt member 61 generates heat (self-heating).

  The control unit (not shown) includes a microcomputer, a storage element such as a RAM and a ROM, and the like, and based on the surface temperature of the belt member 61 detected by the temperature detection unit (not shown), a power source (not shown). The sheet P sent to the fixing nip portion N is appropriately fixed by controlling the high-frequency current supplied to the coil 64a.

  When the belt member 61 is heated and heated to a fixable temperature, the paper P sandwiched by the fixing nip portion N is heated and pressed by the pressure roller 63, so that the powder state on the paper P is changed. The toner is melted and fixed on the paper P. The fixed sheet P is separated from the outer peripheral surface of the belt member 61. Thus, since the belt member 61 is made of a thin material having good thermal conductivity and has a small heat capacity, the fixing device 5 can be warmed up in a short time, and image formation is started quickly.

  In the belt fixing type fixing device 5, when the belt member 61 passes through the fixing nip portion N where load is applied, or when the parallelism between the belt inner rollers 62 (the fixing roller 65 and the heat roller 66) is low, the belt Since the member 61 is offset (meanders) in the axial direction of the fixing roller 65, in the present embodiment, the regulating member (the first regulating member 67 and the second regulation) that regulates the deviation (meandering) of the belt member 61 in the axial direction. A member 68) is provided.

  As shown in FIG. 3, a pair of first restriction members 67 are provided at both axial ends of the fixing roller 65, and a pair of second restriction members 68 are provided at both axial ends of the heat roller 66. That is, when the fixing roller 65 is the most downstream in the rotation direction of the belt member 61 (clockwise direction in FIG. 2), the second restriction member 68 is upstream of the rotation direction of the belt member 61 compared to the first restriction member 67. Placed on the side.

  The first restricting member 67 is formed in a substantially disc shape and is fixed to both ends of the core metal 65 a of the fixing roller 65. The first regulating member 67 includes a regulating surface 67 a that moves the belt member 61 inward in the axial direction of the fixing roller 65. The restriction surface 67a is formed in an inclined surface (tapered shape) that is inclined with respect to the axial direction of the fixing roller 65 when viewed in cross section. The restriction surface 67a may be formed to have an R shape when viewed in cross section.

  The restricting surface 67a includes a first position P67a that is located on the inner side in the axial direction of the fixing roller 65, a second position P67b that is located on the outer side in the axial direction of the fixing roller 65, and has a larger diameter than the first position P67a. Have

  Similarly to the first restriction member 67, the second restriction member 68 is formed in a substantially disk shape, and is fixed to both ends of the iron base material 66a of the heat roller 66. The second restriction member 68 includes a restriction surface 68 a that moves the belt member 61 inward of the heat roller 66 in the axial direction. The restriction surface 68a is formed in an inclined surface (tapered shape) that is inclined with respect to the axial direction of the heat roller 66 when viewed in cross section. The restricting surface 68a may be formed to have an R shape when viewed in cross section.

  Further, the regulation surface 68a includes a first position P68a located on the inner side in the axial direction of the heat roller 66, a second position P68b located on the outer side in the axial direction of the heat roller 66 and having a larger diameter than the first position P68a, Have

  The distance between the first positions P67a of the pair of first restricting members 67 is x1, the distance between the second positions P67b of the pair of first restricting members 67 is x1max, and the distance between the pair of second restricting members 68. When the distance between the first positions P68a is x2, and the distance between the second positions P68b of the pair of second restriction members 68 is x2max, the first restriction member 67 and the second restriction member 68 are x1. They are arranged so as to satisfy the relationship of <x2 <x1max <x2max.

  With the above configuration, when the belt member 61 is offset in the axial direction, the side end portion of the belt member 61 is returned (moved) to the first position P68a by the second restriction member 68, and then the first restriction member 67 It is returned (moved) to the 1 position P67a. In this way, the deviation of the belt member 61 is eliminated.

  In the present embodiment, as described above, the pair of first restricting members 67 and the pair of second restricting members 68 are respectively provided at both ends in the axial direction of the two in-belt rollers 62. The distance between the first positions P67a of the first restricting member 67 is x1, the distance between the second positions P67b of the pair of first restricting members 67 is x1max, and the first positions P68a of the pair of second restricting members 68 are the same. When the distance between the first restriction member 67 and the second restriction member 68 is x2, the first restriction member 67 and the second restriction member 68 are disposed so as to satisfy the relationship of x1 <x2 <x1max. As a result, when the belt member 61 is offset, the first regulating member is moved after the side end of the belt member 61 is returned (moved) to the first position P68a of the second regulating member 68 by the second regulating member 68. 67, the first restricting member 67 is returned (moved) to the first position P67a. That is, the belt member 61 can be gradually returned (moved) to a predetermined position. For this reason, since it can suppress that the load concerning the belt member 61 becomes large in the contact part of the regulating member (the 1st regulating member 67 and the 2nd regulating member 68) and the belt member 61, the belt member 61 is damaged. Can be suppressed.

  Further, as described above, when the fixing roller 65 is located at the most downstream side in the rotation direction of the belt member 61, the second restriction member 68 is disposed on the upstream side in the rotation direction of the belt member 61 compared to the first restriction member 67. Has been. Accordingly, the deviation of the belt member 61 can be gradually eliminated toward the fixing nip portion N by the second restriction member 68 and the first restriction member 67. For this reason, it is possible to suppress the occurrence of fixing failure due to the deviation of the belt member 61 in the fixing nip portion N.

  Further, as described above, the first regulating member 67 is provided on the fixing roller 65. Thereby, the deviation of the belt member 61 can be minimized in the fixing nip portion N, which is more effective. Further, since the fixing roller 65 has a relatively large roller diameter and a relatively large amount (contact area) with the belt member 61, the fixing roller 65 is provided with a first regulating member 67, and the belt member 61 is provided at the fixing roller 65 portion. It is particularly effective to eliminate the deviation of the.

  As described above, when the distance between the second positions P68b of the pair of second restricting members 68 is x2max, the first restricting member 67 and the second restricting member 68 have x1 <x2 <x1max <x2max. It is arranged to satisfy the relationship. Thereby, since the regulating surface 68a of the second regulating member 68 is arranged to the outside in the axial direction than the regulating surface 67a of the first regulating member 67, even if the deviation of the belt member 61 is large, the belt The deviation of the member 61 can be easily eliminated.

(Second Embodiment)
Next, the fixing device 5 according to the second embodiment of the present invention will be described with reference to FIG.

  In the fixing device 5 according to the second embodiment of the present invention, as shown in FIG. 4, the in-belt roller 62 includes a tension roller 69 that applies tension to the belt member 61 in addition to the fixing roller 65 and the heat roller 66. .

  The tension roller 69 is in contact with the inner surface of the belt member 61 from the fixing roller 65 toward the heat roller 66. The tension roller 69 presses the belt member 61 toward the outer peripheral surface side by being biased by a biasing member (not shown). Thereby, it is possible to prevent the belt member 61 from being bent. In particular, when the electromagnetic induction type induction heating unit 64 is used, in order to keep the distance between the induction heating unit 64 and the heat roller 66 constant, the induction heating unit 64 is applied to the bearing portion of the heat roller 66 with a spring force. A configuration in which the pressure is pressed is often used. In this case, the distance between the heat roller 66 and the fixing roller 65 is reduced, and the belt member 61 is likely to bend. However, by providing the tension roller 69, the belt member 61 can be easily prevented from being bent. This is possible, and the tension of the belt member 61 can be stabilized.

  The tension roller 69 is made of a material having high thermal conductivity such as aluminum. As a result, the temperature distribution in the axial direction of the belt member 61 can be made uniform, so that the temperature distribution in the axial direction of the belt member 61 can be made uniform even when continuously printing on a small size sheet. It is possible to suppress the occurrence of fixing failure.

  The tension roller 69 has a smaller roller diameter than the fixing roller 65 and the heat roller 66, and the amount of contact (contact area) with the belt member 61 is also small. For this reason, the restricting members (the first restricting member 67 and the second restricting member 68) that restrict the deviation of the belt member 61 are not provided in the tension roller 69, and as in the first embodiment, the fixing roller. A first restriction member 67 is provided at 65, and a second restriction member 68 is provided at the heat roller 66.

  Other structures of the second embodiment are the same as those of the first embodiment.

  In the present embodiment, as described above, the heat roller 66 has a larger roller diameter than the tension roller 69 and a large amount (contact area) with the belt member 61, so even when the tension roller 69 is provided, It is particularly effective to provide the second regulating member 68 on the heat roller 66.

  Other effects of the second embodiment are the same as those of the first embodiment.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above-described embodiment, an example in which the induction heating unit 64 is provided around the heat roller 66 and the belt member 61 is heated by electromagnetic induction has been described. However, the present invention is not limited thereto, and a halogen is provided inside the heat roller 66. The belt member 61 may be heated by providing a heater or the like.

  Moreover, although the example which does not heat the pressure roller 63 was shown in the said embodiment, this invention is not limited to this, A halogen heater etc. are provided in the inside of the pressure roller 63, and not only the belt member 61 but a pressure roller. 63 may also be heated.

  Moreover, in the said embodiment, although the temperature detection part was shown about the example comprised so that the temperature of a belt member might be detected, this invention is not limited to this, A temperature detection part seems to detect the temperature of each roller. You may comprise.

  In the above-described embodiment, the example in which the second restricting member 68 is arranged on the upstream side in the rotation direction of the belt member 61 as compared with the first restricting member 67 is shown, but the present invention is not limited to this, and the second restricting member. 68 may be arranged on the downstream side in the rotation direction of the belt member 61 as compared with the first regulating member 67.

  In the second embodiment, when the in-belt roller 62 includes the fixing roller 65, the heat roller 66, and the tension roller 69, the restriction member (the first restriction member 67 and the second restriction member 68) is used as the tension roller 69. However, the present invention is not limited to this example. One of the regulating members (the first regulating member 67 and the second regulating member 68) may be provided on the tension roller 69. However, since the tension roller 69 has a relatively small amount of contact (contact area) with the belt member 61, the tension roller 69 is preferably provided with a second regulating member 68.

  Moreover, in the said embodiment, it showed about the case where the 2nd position P68b of the 2nd control member 68 is arrange | positioned to the outer side of the axial direction rather than the 2nd position P67b of the 1st control member 67 (when x1max <x2max). However, the present invention is not limited to this. The second position P67b of the first restricting member 67 may be disposed to the outside in the axial direction from the second position P68b of the second restricting member 68.

  Further, a configuration obtained by appropriately combining the configurations of the above-described embodiment and modification examples is also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Fixing apparatus 61 Belt member 62 In-belt roller 63 Pressure roller 64 Induction heating part (heating member)
65 fixing roller 66 heat roller 67 first regulating member 67a regulating surface 68 second regulating member 68a regulating surface 69 tension roller N fixing nip P paper (recording medium)
P67a, P68a First position P67b, P68b Second position x1, x1max, x2, x2max Distance

Claims (6)

An endless belt member heated by a heating member;
Two or more in-belt rollers that are rotatable and in contact with the inner peripheral surface of the belt member;
A rotatable pressure roller disposed opposite to the outer circumferential surface of the belt member and pressed against one of the rollers in the belt via the belt member;
A fixing device that fixes a non-fixed toner image on the recording medium by inserting a recording medium through a fixing nip formed by the belt member and the pressure roller,
A pair of first restricting members and a pair of second restricting members that restrict the belt members from shifting in the axial direction of the in-belt rollers are respectively provided at both axial ends of the two in-belt rollers. And
Each of the first restriction member and the second restriction member includes a restriction surface that moves the belt member inward in the axial direction of the in-belt roller,
The restriction surface has a first position located on the inner side in the axial direction of the inner roller of the belt and a second position located on the outer side in the axial direction of the inner roller and larger in diameter than the first position. And
The distance between the first positions of the pair of first restricting members is x1, the distance between the second positions of the pair of first restricting members is x1max, and the first positions of the pair of second restricting members are When the distance between the first restriction member and the second restriction member is x2, the first restriction member and the second restriction member are arranged so as to satisfy a relationship of x1 <x2 <x1max .
The in-belt roller includes a fixing roller pressed against the pressure roller via the belt member, and a heat roller disposed to face the fixing roller,
When the fixing roller is at the most downstream side in the rotation direction of the belt member, the second restriction member is disposed on the inner belt roller on the upstream side in the rotation direction of the belt member as compared with the first restriction member. A fixing device. The said regulation surface is formed in the inclined surface (taper shape) which inclines in the axial direction of the said roller in a belt seeing in cross section, or it is formed so that it may have a R shape. The fixing device according to 1. The first regulating member, a fixing device according to claim 1 or 2, characterized in that provided on the fixing roller. The in-belt roller includes a tension roller that applies tension to the belt member,
The fixing device according to claim 3, wherein the second regulating member is provided on the heat roller.   When the distance between the second positions of the pair of second restricting members is x2max, the first restricting member and the second restricting member are arranged so as to satisfy the relationship of x1 <x2 <x1max <x2max. The fixing device according to claim 1, wherein the fixing device is a fixing device.   An image forming apparatus comprising the fixing device according to claim 1.

Images