JP2017161582A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of preventing damage to an end surface of a fixing belt.SOLUTION: A fixing device 18 includes: a fixing belt 31 that is rotatably provided having a rotation shaft 44 as a central portion and is heated by a heat source 34; a pressure rotation member 32 that rotates in close contact with the fixing belt 31 to form a fixing nip 40 between the fixing belt 31 and the pressure rotation member; an end surface receiving member 36 that is provided so as to be opposite to an end surface of the fixing belt 31 and is elastically deformable; and a backup member 43 that supports the end surface receiving member 36 on an opposite side from the end surface of the fixing belt 31. On a surface, opposite to the end surface receiving member 36, of the backup member 43 are formed a retreat part 43a provided so as to be separated from the fixing nip 40 in a rotation shaft direction and a guiding part 45 that deforms the end surface receiving member 36 so as to dispose the end surface receiving member along the retreat part 43a.SELECTED DRAWING: Figure 3

Description

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

  In an electrophotographic image forming apparatus, a toner image transferred onto a sheet is fixed on the sheet by a fixing device. The fixing device has a fixing member such as a fixing roller and a fixing belt to be heated and a pressure rotating member, and when the sheet passes through a fixing nip formed between the fixing member and the pressure rotating member, The toner image is heated and pressurized and fixed on the paper.

  In a belt fixing method using a fixing belt as a fixing member, both ends of the fixing belt are rotatably supported by a rotating shaft portion, and are pressed against a pressure rotating member between the rotating shaft portions. The fixing belt rotates around the rotation shaft portion by following the pressure rotating member. Since both ends of the fixing belt are not fixed in this way, depending on the influence of dimensional tolerances and the like, there is a tendency to be displaced in either direction of the rotation axis during driven rotation. If this deviation is large, a fixing nip having a predetermined width may not be formed.Therefore, the fixing device is provided so as to face both end faces of the fixing belt and moves in the direction along the rotation axis of the fixing belt. An end face receiving member that regulates may be provided.

  The end face receiving member is made of a material having good slidability, and even if the end face of the fixing belt contacts, the end face is not damaged. The end face receiving member also acts to push back in the opposite direction by the reaction force when the fixing belt comes into contact therewith.

  Patent Documents 1 and 2 describe a fixing device provided with such an end face receiving member. The fixing device described in Patent Document 1 has two end face receiving members arranged side by side in the axial direction of the rotation shaft. The friction coefficient between the two end face receiving members is made smaller than the friction coefficient between the end face receiving member on the fixing belt side and the end face of the fixing belt, thereby preventing the end face of the fixing belt from being damaged. In the fixing device described in Patent Document 2, the contact portion of the end surface receiving member with the end surface of the fixing belt is formed in a bimetal shape so as to be elastically deformable.

JP 2013-178291 A JP 2006-65250 A

  As described above, since the fixing belt receives a rotational force from the pressure rotator in the fixing nip, the force for moving the fixing belt in the direction of the rotation axis is increased in the vicinity of the fixing nip. On the other hand, since the fixing belt and the pressure rotator are in pressure contact with each other in the fixing nip, the fixing belt does not slide in the direction of the rotation axis in the vicinity of the fixing nip. Therefore, when the fixing belt is displaced in the rotation axis direction, a strong sliding force acts between the end face of the fixing belt near the fixing nip and the end face receiving member.

  However, in the fixing device described in Patent Document 1, there is a possibility that the end face receiving member may come into contact with the portion facing the end face of the fixing belt even in the vicinity of the fixing nip, and the fixing belt may be damaged. Further, in the fixing device described in Patent Document 2, the end face receiving member is deformed by abutting against the end face of the fixing belt. However, the fixing is performed when the end face of the fixing belt and the end face receiving member abut. A constant pressure is applied to the belt, which may damage the fixing belt. Further, when the end face receiving member is elastically deformed, there is a possibility that the smooth rotation of the fixing belt is hindered.

  In view of the above circumstances, an object of the present invention is to provide a fixing device and an image forming apparatus that can reduce the stress applied to the end surface of the fixing belt in the vicinity of the fixing nip and improve the durability of the fixing belt.

  In order to solve the above-described problems, a fixing device according to the present invention includes a fixing belt that is rotatably provided around a rotation shaft and that is heated by a heat source, and is rotated in pressure contact with the fixing belt. A pressure rotating member that forms a fixing nip therebetween, an elastically deformable end surface receiving member provided so as to face the end surface of the fixing belt, and the end surface receiving member supported on the side opposite to the end surface of the fixing belt A back-up member that is disposed on a surface facing the end face receiving member so as to be separated from the fixing nip in the rotation axis direction, and the end face receiving member is retracted. And a guide portion that is deformed along the portion.

  By adopting such a configuration, the end surface of the fixing belt corresponding to the fixing nip does not come into contact with the end surface receiving member, so that the fixing belt can be reliably prevented from being damaged and the durability of the fixing belt can be improved.

  In the fixing device of the present invention, the end face receiving member is supported so as to be rotatable about the rotation axis, and after being deformed along the retracting portion during rotation about the rotation axis, It may be characterized by returning to the shape.

  By adopting such a configuration, even when the end face receiving member rotates following the fixing belt, the end face receiving member is deformed to the side away from the fixing belt in the vicinity of the fixing nip. In other portions, the end face receiving member can be brought into contact with the end face of the fixing belt.

  In the fixing device of the present invention, the retracting portion may be inclined in a direction away from the fixing nip.

  By adopting such a configuration, the end face receiving member is easily deformed along the retracting portion.

  In the fixing device according to the aspect of the invention, the guide portion may be disposed at a predetermined interval along the outer peripheral edge of the retracting portion so as to be engaged with the outer peripheral portion of the end face receiving member. It is good as a feature.

  By adopting such a configuration, the frictional resistance between the end face receiving member and the guide portion can be reduced during rotation of the end face receiving member. Therefore, when the end face receiving member rotates following the fixing belt, The rotation can be prevented.

  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 prevent the end face of the fixing belt from coming into contact with the end face receiving member in the vicinity of the fixing nip, so that the stress applied to the end face of the fixing belt is reduced and durability can be improved.

1 is a schematic diagram illustrating an outline of a printer according to an embodiment of the present invention. 1 is a front sectional view of a fixing device according to an embodiment of the present invention. FIG. 3 is a side sectional view showing one end portion of the fixing belt in the fixing device according to the embodiment of the present invention. FIG. 3 is a front view showing an end face receiving member supported by an end cap in the fixing device according to the embodiment of the present invention.

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

  First, the overall configuration of a printer 1 as an image forming apparatus will be described with reference to FIG. FIG. 1 is a diagram schematically showing an outline of the printer 1. In the following, the front side of the paper in FIG. 1 is the front side (front side) of the printer, and the left and right directions will be described with reference to the direction viewed from the front of the printer.

  The printer 1 includes a rectangular parallelepiped printer body 2. A paper feed cassette 3 for containing paper S is accommodated in the lower part of the printer main body 2, and a paper feed unit 4 is provided at the upper left of the paper feed cassette 3. A paper discharge tray 5 is provided on the upper surface of the printer main body 2. An upper cover 6 is attached to the left side of the paper discharge tray 5 so as to be openable and closable, and a toner container 7 is stored below the upper cover 6.

  An exposure unit 9 composed of a laser scanning unit (LSU) is provided below the discharge tray 5, and an image forming unit 10 is provided below the exposure unit 9. A photosensitive drum 11 is rotatably provided in the image forming unit 10, and a transfer nip 14 is provided around the photosensitive drum 11 between the charger 12, the developing device 13, and the photosensitive drum 11. And a cleaning device 16 are arranged along the direction of rotation of the photosensitive drum 11 (see arrow X in FIG. 1). A fixing device 18 is provided on the right side of the image forming unit 10, and a paper discharge unit 19 facing the paper discharge tray 5 is provided above the fixing device 18.

  The printer main body 2 is provided with a paper conveyance path 20 from the paper supply unit 4 to the paper discharge unit 19 through the transfer nip 14 and the fixing device 18. A reverse path 21 for double-sided printing is formed below the transport path 20.

  Next, an image forming operation of the printer 1 having such a configuration will be described. First, after the surface of the photosensitive drum 11 is charged by the charger 12, exposure corresponding to the image data is performed on the photosensitive drum 11 by laser light from the exposure device 9 (see a two-dot chain line in FIG. 1). As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 11. Next, the electrostatic latent image is developed into a toner image by the developing device 13 with toner.

  On the other hand, the paper S taken out from the paper feed cassette 3 by the paper feed unit 4 is conveyed to the transfer nip 14 in synchronization with the above-described image forming operation, and the toner image on the photosensitive drum 11 is transferred to the transfer nip 14. Transferred to paper. The sheet on which the toner image has been transferred is conveyed downstream in the conveyance path 20 and enters the fixing device 18, where the toner image is heated and pressurized and 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 5. The toner remaining on the photosensitive drum 11 is collected by the cleaning device 16.

  Next, the fixing device 18 will be described with reference to FIGS. 2 is a front sectional view showing the fixing device, FIG. 3 is a side sectional view showing one end portion of the fixing device, and FIG. 4 is a front view of the end surface receiving member.

  The fixing device 18 includes a fixing belt 31, a pressure roller 32 that is a pressure rotation member provided below the fixing belt 31, and a pressing member provided in a hollow portion of the fixing belt 31 so as to face the pressure roller 32. 33, a halogen heater 34 as a heat source provided in the hollow portion of the fixing belt 31, end caps 35 (see FIG. 3) provided at both ends of the fixing belt 31, and opposite ends of the fixing belt 31, respectively. And an end face receiving member 36.

  The fixing belt 31 is an endless belt having a length longer than the maximum sheet passing width. The fixing belt 31 is formed of a flexible material, and includes, for example, a base layer, an elastic layer provided around the base layer, and a release layer that covers the elastic layer. Yes. The base material layer is made of, for example, a metal such as SUS or a resin such as PI (polyimide), the elastic layer is made of, for example, silicone rubber, and the release layer is made of, for example, PFA (tetrafluoroethylene-perfluoroalkyl). Vinyl ether copolymer) tube.

  The pressure roller 32 is shorter than the fixing belt 31 and has the same length as the maximum sheet passing width. The pressure roller 32 is formed of a cylindrical core material, an elastic layer provided around the core material, and a release layer that covers the elastic layer. The core material is made of, for example, a metal such as iron, the elastic layer is made of, for example, silicone rubber, and the release layer is made of, for example, a PFA tube.

  The pressure roller 32 is supported so as to be rotatable in the clockwise direction of FIG. 2 about the rotation shaft 32a.

  The pressing member 33 is a substantially rectangular parallelepiped member whose cross-sectional shape has a length equivalent to that of the fixing belt 31, and the angle between the lower surface and both side surfaces is curved in an arc shape. The pressing member 33 is supported by the support member 38 so as to press the fixing belt 31 downward toward the pressure roller 32.

  When the fixing belt 31 is pressed downward by the pressing member 33, the fixing belt 31 is pressed against the pressure roller 32, and a fixing nip 40 is formed between the fixing belt 31 and the pressure roller 32. The fixing belt 31 is deformed so as to be curved upwardly by being pressed against the pressure roller 32. On the other hand, the pressure roller 32 is not in pressure contact with both ends of the fixing belt 31, and both ends of the fixing belt 31 have a shape close to a perfect circle. When the pressure roller 32 is rotated, as shown in FIG. 2, the fixing belt 31 is driven by the pressure roller 32 and rotates in the direction opposite to the rotation direction of the pressure roller 32.

  The halogen heater 34 is disposed above the hollow portion of the fixing belt 31 and radiates radiant heat toward the fixing belt 31.

  As shown in FIG. 3, the end cap 35 protrudes into a disk-shaped backup member 43 having a diameter larger than the outer diameter of the fixing belt 31 and the inner surface of the backup member 43 (the surface on the fixing belt 31 side). The fixing belt 31 has a rotating shaft portion 44 as a rotating shaft that rotates along the outer peripheral surface. On the inner surface of the backup member 43, a retraction surface 43 a that is inclined downward toward the outer side in the axial direction of the rotation shaft portion 44 is formed in a portion about 1/3 from the bottom. That is, the retracting surface 43 a is formed so as to be separated from the fixing nip 40 in the axial direction of the rotating shaft portion 44.

  As shown in FIG. 4, two guide portions 45 are formed on the outer peripheral portion of the retracting surface 43a with a predetermined interval in the circumferential direction. The guide portion 45 includes a leg piece 45a that is erected vertically from the retraction surface 43a, and an engagement piece 45 that extends radially inward from the tip of the leg piece 45a.

  The rotating shaft portion 44 has a cylindrical shape with an approximately 3/4 arc shape with a cross-sectional convex upward, and a groove-shaped small-diameter portion 44a is formed along the outer periphery on the base end side. Both end portions of the fixing belt 31 are fitted on the respective rotation shaft portions 44 so as to be rotatable along the outer peripheral surface of each rotation shaft portion 44. Further, both end portions of the halogen heater 34 and both end portions of the support member 38 are supported by the backup member 43 through the hollow portion of the rotating shaft portion 44.

  The end face receiving member 36 is a disk-shaped member having an outer diameter larger than the outer diameter of the fixing belt 31. The end face receiving member 36 is formed of a sheet material that has good slidability and can be elastically deformed. For example, metals such as SECC and SUS, PPS, PEEK, PAI, PI, fluororesin, and the like can be used.

  The end surface receiving member 36 is inserted into the small diameter portion 44a of the rotation shaft portion 44 outside the end surface of the fixing belt 31, can rotate around the small diameter portion 44a, and can slide along the axial direction of the small diameter portion 44a. It has become. As shown in FIG. 3, the end surface receiving member 36 is deformed along the retracting surface 43 a of the backup member 43, and the outer peripheral portion is engaged with the engaging pieces 45 b of the two guide portions 45.

  In the fixing device 18 having the above configuration, the fixing belt 31 is heated by the halogen heater 34 when the toner image is fixed on the paper. Further, when the fixing belt 31 rotates following the rotation of the pressure roller 32 and the sheet S is conveyed to the fixing nip 40 along the conveyance path 20, the toner image is heated and pressurized and fixed to the sheet S. Is done.

  During such a fixing operation, both end surfaces of the fixing belt 31 face the end surface receiving members 36, respectively. In the vicinity of the fixing nip 40, both end faces of the fixing belt 31 face the end face receiving member 36 supported by the guide portion 45 along the retreating face 43 a of the backup member 43.

  If the fixing belt 31 is shifted in one axial direction of the rotation shaft portion 44 while rotating, the end surface of the fixing belt 31 comes into contact with the end surface receiving member 36 and the deviation is restricted. Since the end face receiving member 36 is formed of a material having good sliding properties, even if the end face of the fixing belt 31 comes into contact, the end face of the fixing belt 31 is not damaged. In the vicinity of the fixing nip 48, the end surface of the fixing belt 31 is separated from the end surface receiving member 36. Therefore, in the vicinity of the fixing nip 48, the end surface of the fixing belt 31 and the end surface receiving member 36 come into contact with each other and slide. There is nothing to move. Since the sliding distance in the axial direction of the small diameter portion 44a of the end face receiving member 36 is short, the offset width of the fixing belt 31 does not increase.

  Further, when the end edge of the fixing belt 31 contacts the end surface receiving member 36 as described above, the end surface receiving member 36 may be driven by the fixing belt 31 to rotate around the small diameter portion 44 a of the rotating shaft portion 44. In this case, the end surface receiving member 36 rotates while being deformed along the retracting surface 43a by the guide portion 45. Therefore, even if the end surface receiving member 36 rotates, the end surface corresponding to the vicinity of the fixing nip 40 does not move. It is separated from the member 36. The end face receiving member 36 returns to its original shape after being deformed along the retracting face 43a.

  As described above, according to the fixing device 18 of the present invention, the retracting surface 43a is formed on the backup member 43 in the vicinity of the fixing nip 40, and the end surface receiving member 36 is deformed so as to follow the retracting surface 43a. Therefore, the end surface of the fixing belt 31 does not contact the end surface receiving member 36 in the vicinity of the fixing nip 40. Therefore, stress applied to the end face of the fixing belt 31 is reduced and damage can be prevented, so that the durability of the fixing belt 31 can be improved.

  In the present embodiment, since the inclined retraction surface 43a is formed as the retraction portion provided so as to be separated from the fixing nip 40 in the axial direction of the rotation shaft portion 44, the end surface receiving member 36 extends along the retraction surface 43a. It is easy to deform. Note that the retracting portion can be formed in a stepped shape, a notch shape, or the like.

  Even when the end surface receiving member 36 rotates following the fixing belt 31, the retracting surface 43 a can be rotated while deforming the end surface receiving member 36 away from the fixing belt 31. Since the end surface receiving member 36 returns to its original shape after passing through the retracting surface 43 a, the end surface receiving member 36 comes into contact with the end surface of the fixing belt 31 at a portion other than the vicinity of the fixing nip 40. In the present embodiment, the case where the end surface receiving member 36 is rotatably provided around the small diameter portion 44 a of the rotating shaft portion 44 has been described. However, the end surface receiving member 36 is supported by the rotating shaft portion 44 so as not to rotate. May be.

  Furthermore, since the end surface receiving member 36 is engaged with the two guide portions 45, the friction resistance between the end surface receiving member 36 and the guide portion 45 is reduced when the end surface receiving member 36 is rotated, and the end surface receiving member 36 is moved. It can be rotated smoothly.

  In the embodiment of the present invention, the case where the configuration of the present invention is applied to the printer 1 has been described. However, in another different embodiment, the image forming apparatus other than the printer 1 such as a copying machine, a facsimile machine, and a multifunction machine is used. A configuration may be applied.

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

1 Printer (image forming device)
18 Fixing Device 31 Fixing Belt 32 Pressure Roller (Pressure Rotating Member)
36 End face receiving member 43 Backup member 43a Retraction surface (retraction portion)
44 Rotating shaft (Rotating shaft)
45 Guide

Claims (5)

A fixing belt which is rotatably provided around a rotation axis and is heated by a heat source;
A pressure rotating member that forms a fixing nip with the fixing belt by rotating in pressure contact with the fixing belt;
An elastically deformable end face receiving member provided to face the end face of the fixing belt;
A backup member that supports the end face receiving member on the side opposite to the end face of the fixing belt,
The backup member has a retracting portion provided on a surface facing the end surface receiving member so as to be separated from the fixing nip in the rotation axis direction, and a guide for deforming the end surface receiving member along the retracting portion. A fixing device.   The end face receiving member is supported so as to be rotatable about the rotating shaft, and after being deformed along the retracting portion during rotation about the rotating shaft, the end surface receiving member is restored to its original shape. The fixing device according to claim 1.   The fixing device according to claim 1, wherein the retracting portion is inclined in a direction away from the fixing nip.   The said guide part is arrange | positioned at predetermined intervals along the outer periphery of the said evacuation part, and it is provided so that it may engage with the outer peripheral part of the said end surface receiving member. The fixing device described.   An image forming apparatus comprising the fixing device according to claim 1.

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