JP2016197204A - Transfer device and image forming apparatus including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer device that has improved attachability/detachability of a transfer roller rotatably supported by bearings, and an image forming apparatus including the same.SOLUTION: A transfer device comprises a housing and a roller unit 35U. The roller unit 35U includes a rear bearing 351, a front bearing 352, and a retaining member 36. The housing includes a pair of support members that supports the rear bearing 351 and front bearing 352. When the roller unit 35U is attached to the housing, the rear bearing 351 and front bearing 352 are supported by the supporting members of the housing, and subsequently the retaining member 36 is rotated around a shaft front end part 35B, and thereby the retaining member 36 is locked to a locking part of the housing.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a transfer device that transfers an image to a sheet, and an image forming apparatus including the transfer device.

  Conventionally, an image forming apparatus provided with a transfer device is known. The image forming apparatus includes an image carrier in addition to the transfer device. The transfer device also includes a transfer roller. The image formed on the image carrier is transferred to a sheet using a transfer roller. Patent Document 1 discloses a technique in which both ends of a transfer roller are supported by bearings.

JP-A-4-271380

  In the above transfer device, the pair of bearings are supported by the bushes. The bush is in contact with the entire circumferential direction of the bearing. For this reason, in order to replace the transfer roller, it is necessary to remove a plurality of members around the bearing.

  The present invention has been made to solve the above-described problems, and provides a transfer device that improves the detachability of a transfer roller that is rotatably supported by a bearing, and an image forming apparatus including the transfer device. The purpose is to do.

  A transfer device according to one aspect of the present invention includes a housing and a transfer roller that is in contact with an image carrier that carries a developer image on a surface thereof, is rotated, and transfers the developer image to a sheet. A roller unit mounted on the housing along a mounting direction that intersects the axial direction, and the transfer roller includes a shaft portion that protrudes from both end sides in the axial direction, A pair of bearings attached to the shaft portion at both ends of the transfer roller, and a retaining member externally fitted to the shaft portion so as to be adjacent to the bearing at one end side in the axial direction, The housing includes a pair of support members that respectively support the outer peripheral surfaces of the pair of bearings, and each of the pair of support members includes an opening in which a part of the rotation in the circumferential direction is opened. A cylindrical shape having a predetermined thickness along the axial direction, the support member on one end side in the axial direction includes a locking portion, and when the roller unit is mounted on the housing, After the bearing is supported by the support member, when the retaining member is rotated around the shaft portion, the retaining member is locked to the locking portion.

  According to this configuration, the pair of support members each include an opening. And a pair of bearing of a roller unit is each supported by the support member. As a result, the transfer roller is rotatably supported by the bearing and the support member. Furthermore, the retaining member is locked to the locking portion by rotating the retaining member. This prevents the roller unit from being detached from the housing. As a result, a transfer device with improved transfer roller detachability is provided.

  In the above configuration, the retaining member includes a cylindrical portion that is externally fitted to the shaft portion, and an extending portion that extends from the cylindrical portion in the radial direction in the rotation and is engageable with the locking portion. It is desirable that the extending portion is elastically deformable so as to fall in the axial direction.

  According to this configuration, since the extended portion of the retaining member can be elastically deformed, the retaining operation of the retaining member is easily realized.

  In the above configuration, the locking portion is a hole portion opened in the support member, the extension portion of the retaining member includes a protrusion, and the roller unit is attached to the housing. When the extension portion is elastically deformed to the other end side in the axial direction, the retaining member is rotated around the shaft portion, and then the elastic deformation of the extension portion is restored. It is desirable that the protrusion is locked in the hole.

  According to this configuration, the locking operation of the retaining member is more easily realized by locking the protrusions in the holes.

  In the above-described configuration, it is preferable that the extension portion of the retaining member includes a grip portion that is gripped in the rotation around the shaft portion.

  According to this structure, the rotation and locking operation of the retaining member is easily realized.

  In the above configuration, the pair of support members includes an opening in which a part in a circumferential direction in the rotation of the transfer roller is opened, and has a substantially cylindrical shape having a predetermined thickness along the axial direction. Preferably, the opening width of the opening of the support member on one end side in the axial direction is set larger than the opening width of the opening of the support member on the other end side in the axial direction. .

  According to this configuration, the support member on the other end side in the axial direction can stably support the outer peripheral surface of the bearing, and the bearing is prevented from being detached from the support member. In addition, at one end side in the axial direction, the bearing can be easily attached to and detached from the support member.

  In the above configuration, after the bearing on the other end side in the axial direction of the roller unit is mounted on the support member along the axial direction, the bearing on the one end side in the axial direction is orthogonal to the axial direction. It is desirable that the roller unit is supported by the pair of support members by being attached to the support member along the direction of the support.

  According to this configuration, the attachment and detachment of the roller unit can be achieved smoothly and easily compared to the case where the support member does not include the opening.

  An image forming apparatus according to another aspect of the present invention includes any one of the transfer apparatuses described above and the image carrier that carries a developer image on a surface thereof.

  According to this configuration, the roller unit is prevented from being detached from the housing. In addition, an image forming apparatus including a transfer device with improved transfer roller detachability is provided. As a result, even when the life of the transfer roller is shorter than the life of the image forming apparatus, the transfer roller can be easily replaced and the time during which the use of the image forming apparatus is interrupted due to the replacement is reduced. Is done.

  According to the present invention, there are provided a transfer device that improves the detachability of a transfer roller that is rotatably supported by a bearing, and an image forming apparatus including the transfer device.

1 is a cross-sectional view showing an internal structure of an image forming apparatus according to an embodiment of the present invention. 2 is a perspective view of the periphery of a transfer roller of the image forming apparatus according to the embodiment of the present disclosure. FIG. It is a perspective view of the roller unit which concerns on one Embodiment of this invention. 2 is a cross-sectional view of the periphery of a transfer roller of the image forming apparatus according to the embodiment of the present disclosure. FIG. It is a perspective view of the retaining member concerning one embodiment of the present invention. It is a perspective view of the support member concerning one embodiment of the present invention. It is a perspective view of the support member concerning one embodiment of the present invention. It is a perspective view of the support member concerning one embodiment of the present invention. It is a perspective view of the support member concerning one embodiment of the present invention. It is a perspective view of the support member concerning one embodiment of the present invention. It is a front view of the support member concerning one embodiment of the present invention. It is a front view of the support member concerning one embodiment of the present invention. It is a perspective view which shows the support structure of the edge part of the axial direction of the transfer roller which concerns on one Embodiment of this invention. It is a perspective view which shows the support structure of the edge part of the axial direction of the transfer roller which concerns on one Embodiment of this invention. It is a perspective view which shows the support structure of the edge part of the axial direction of the transfer roller which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing an internal structure of an image forming apparatus 1 according to an embodiment of the present invention. Here, as the image forming apparatus 1, a multi-function machine having a printer function and a copying function is illustrated, but the image forming apparatus may be a printer, a copier, or a facsimile machine.

<Description of Image Forming Apparatus>
The image forming apparatus 1 includes an apparatus main body 10 having a substantially rectangular parallelepiped housing structure, and an automatic document feeder 20 disposed on the apparatus main body 10. In the apparatus main body 10, a reading unit 25 that optically reads a document image to be copied, an image forming unit 30 that forms a toner image on a sheet, a fixing unit 60 that fixes the toner image on a sheet, and image formation A sheet feeding unit 40 that stores sheets conveyed to the unit 30, and a conveyance path 50 that conveys the sheet from the sheet feeding unit 40 or the sheet feeding tray 46 to the discharge space 10S via the image forming unit 30 and the fixing unit 60. , Is housed. The sheet S discharged to the discharge space 10S is stacked on the paper discharge unit 101.

  An automatic document feeder (ADF) 20 automatically feeds a document sheet to be copied toward a predetermined document reading position in the apparatus body 10. On the other hand, when the user manually places the document sheet on a predetermined document reading position, the ADF 20 is opened upward. The reading unit 25 optically reads an image of a document sheet automatically fed from the ADF 20 on the upper surface of the apparatus main body 10 or a manually placed document sheet.

  The image forming unit 30 generates a full-color toner image and transfers it onto the sheet to form an image on the sheet. Yellow (Y), magenta (M), cyan ( An image forming unit 32 including four units 32Y, 32M, 32C, and 32Bk that form toner images of C) and black (Bk), and an intermediate transfer unit 33 disposed adjacent to the image forming unit 32. And a toner replenishing section 34 disposed on the intermediate transfer unit 33.

  Each of the image forming units 32Y, 32M, 32C, and 32Bk includes a photosensitive drum 321 and a charger 322, an exposure device 323, a developing device 324, a primary transfer roller 325, and a cleaning device disposed around the photosensitive drum 321. 326.

  The photosensitive drum 321 rotates around its axis, forms an electrostatic latent image on its surface, and carries a toner image (developer image). The charger 322 uniformly charges the surface of the photosensitive drum 321. The exposure device 323 includes a laser light source and optical system devices such as a mirror and a lens, and forms an electrostatic latent image by irradiating the peripheral surface of the photosensitive drum 321 with light based on image data of a document image. .

  The developing device 324 supplies toner to the peripheral surface of the photosensitive drum 321 in order to develop the electrostatic latent image formed on the photosensitive drum 321. The primary transfer roller 325 primarily transfers the toner image on the photosensitive drum 321 onto the intermediate transfer belt 331. The cleaning device 326 cleans the peripheral surface of the photosensitive drum 321 after the toner image is transferred.

  The intermediate transfer unit 33 includes an intermediate transfer belt 331, a belt driving roller 332, and a driven roller 333. On the outer peripheral surface of the intermediate transfer belt 331, toner images are transferred from a plurality of photosensitive drums 321 to be overlapped at the same location. The intermediate transfer belt 331 is rotated counterclockwise in FIG.

  A secondary transfer roller 35 (transfer roller) is disposed to face the peripheral surface of the belt driving roller 332. The secondary transfer roller 35 is rotated by a drive mechanism (not shown) to transfer the toner image to the sheet. In particular, the nip portion between the belt driving roller 332 and the secondary transfer roller 35 is a secondary transfer portion that transfers a full-color toner image superimposed on the intermediate transfer belt 331 onto a sheet.

  The toner replenishing section 34 includes a yellow toner container 34Y, a magenta toner container 34M, a cyan toner container 34C, and a black toner container 34Bk. The developing devices of the image forming units 32Y, 32M, 32C, and 32Bk corresponding to the respective colors. To 324, the toner of each color is supplied from the discharge screw 341 through a supply path (not shown).

  The paper feed unit 40 includes two-stage paper feed cassettes 40A and 40B that accommodate sheets S subjected to image forming processing. These paper feed cassettes 40A and 40B can be pulled out from the front of the apparatus body 10 toward the front.

  The sheet feeding cassette 40A (40B) includes a sheet storage portion 41 that stores a sheet bundle formed by stacking sheets S, and a lift plate 42 that lifts the sheet bundle for feeding. A pickup roller 43 and a roller pair of a paper feed roller 44 and a retard roller 45 are arranged on the upper right side of the paper feed cassette 40A (40B). By driving the pickup roller 43 and the paper feed roller 44, the uppermost sheet S of the sheet bundle in the paper feed cassette 40A is fed out one by one and carried into the upstream end of the transport path 50.

  The conveyance path 50 is printed on one side when performing double-sided printing on the sheet S and a main conveyance path 50A that conveys the sheet S from the paper feeding unit 40 to the exit of the fixing unit 60 via the image forming unit 30. A double-sided conveyance path 50B for returning the sheet to the image forming unit 30 and an upper discharge path 50C and a lower discharge path 50D for directing the sheet S from the downstream end of the main conveyance path 50A to the discharge space 10S are included.

  A registration roller pair 51 is disposed on the upstream side of the main transfer path 50A from the secondary transfer portion 35A. The sheet S is temporarily stopped by the stopped registration roller pair 51, and skew correction is performed. After that, the registration roller pair 51 is rotationally driven by a drive motor (not shown) at a predetermined timing for image transfer, whereby the sheet S is sent out to the secondary transfer roller 35.

  The fixing unit 60 is an induction heating type fixing device that performs a fixing process for fixing the toner image on the sheet S. A fixing nip portion is formed in the fixing portion 60. As the sheet S passes through the fixing nip portion, the toner image transferred to the sheet S is fixed to the sheet.

Further, the image forming apparatus 1 includes a duplex conveying unit 8 (FIG. 1). FIG. 2 is a perspective view of the periphery of the secondary transfer roller 35 in the duplex conveyance unit 8 of the image forming apparatus 1 according to the present embodiment. The duplex conveyance unit 8 constitutes a part of the right wall 10 </ b> R of the apparatus body 10. The duplex conveying unit 8 includes a fulcrum portion (not shown) at the lower end portion. The duplex conveyance unit 8 is rotatable with respect to the apparatus main body 10 around a fulcrum portion. By the rotation of the duplex conveying unit 8,
The main conveyance path 50 </ b> A or the double-side conveyance path 50 </ b> B is opened to the outside of the apparatus main body 10.

  The double-sided conveyance unit 8 includes a conveyance guide unit 8A and a cover unit 8B (FIG. 2). The conveyance guide unit 8A is a unit arranged inside the right wall 10R (FIG. 1) in the double-sided conveyance unit 8. The left side surface of the transport guide unit 8A defines a main transport path 50A. The right side surface of the transport guide unit 8A defines the left side surface of the double-sided transport path 50B. The cover unit 8B is disposed on the right side of the transport guide unit 8A and constitutes a part of the right wall 10R. The left side surface of the cover unit 8B defines the right side surface of the double-sided conveyance path 50B. When the cover unit 8B is rotated, the double-sided conveyance path 50B is opened. Further, when the transport guide unit 8A is rotated, the main transport path 50A is opened.

  As shown in FIG. 2, a secondary transfer roller 35 is rotatably supported by the transport guide unit 8A. Further, below the secondary transfer roller 35 in the transport guide unit 8A, a registration roller 51A that is one roller of the registration roller pair 51 is rotatably supported. In the present embodiment, the conveyance guide unit 8 </ b> A functions as a housing that supports the secondary transfer roller 35.

  The secondary transfer roller 35 is attached to and detached from the transport guide unit 8A as a roller unit 35U. FIG. 3 is a perspective view of a roller unit 35U according to an embodiment of the present invention. The roller unit 35U is mounted on the transport guide unit 8A along the mounting direction that intersects the axial direction (front-rear direction) in the rotation of the secondary transfer roller 35. The transfer unit of this embodiment is configured by the roller unit 35U including the secondary transfer roller 35 and the transport guide unit 8A. The secondary transfer roller 35 includes a shaft rear end portion 35A (shaft portion) and a shaft front end portion 35B (shaft portion) protruding from both end portions in the axial direction.

  Furthermore, the roller unit 35U includes a rear bearing 351 (bearing), a front bearing 352 (bearing), a gripping roller 35H, and a retaining member 36. The rear bearing 351 and the front bearing 352 are ball bearings mounted on the shaft rear end 35A and the shaft front end 35B, respectively, at both ends of the secondary transfer roller 35. The rotation of the secondary transfer roller 35 is smoothly realized by the rear bearing 351 and the front bearing 352. The gripping roller 35 </ b> H is a cylindrical member attached to the shaft rear end portion 35 </ b> A on the front end side with respect to the rear bearing 351. The gripping roller 35H is gripped by the operator when the roller unit 35U is attached to the transport guide unit 8A. The retaining member 36 is externally fitted to the shaft front end portion 35 </ b> B so as to be adjacent to the front bearing 352 on the front end side of the secondary transfer roller 35. The retaining member 36 has a function of preventing the roller unit 35U attached to the transport guide unit 8A from being detached.

  FIG. 4 is a cross-sectional view of the periphery of the secondary transfer roller 35 of the image forming apparatus 1 according to the present embodiment. The transport guide unit 8A includes a rear bush 81 (FIG. 9) (support member), a front bush 82 (FIG. 4) (support member), and a separation lever 83 (FIG. 2). The rear bush 81 is disposed on the side surface on the rear end side of the conveyance guide unit 8A. The rear bush 81 supports the outer peripheral surface of the rear bearing 351 of the roller unit 35U. On the other hand, the front bush 82 is arranged on the side surface on the front end side of the transport guide unit 8A. The front bush 82 supports the outer peripheral surface of the front bearing 352 of the roller unit 35U. The front bush 82 includes a spring member 82S. The spring member 82S biases the front bush 82 toward the drive roller 332. As a result, the secondary transfer roller 35 is pressed against the driving roller 332. The rear bush 81 also includes a biasing member similar to the spring member 82S. The separation lever 83 has a function of pressing the rear bush 81 and the front bush 82 downward and to the right. In FIG. 2, the separation lever 83 is disposed to face the front bush 82, but the separation lever 83 is also disposed on the rear side of the conveyance guide unit 8A to face the rear bush 81. The separation lever 83 can be swung by a drive mechanism (not shown). The separation lever 83 presses the rear bush 81 and the front bush 82 against the urging force of the spring member 82S, whereby the separation operation of the secondary transfer roller 35 with respect to the belt driving roller 332 is performed.

  FIG. 5 is a perspective view of the retaining member 36 according to the present embodiment. The retaining member 36 includes a cylindrical portion 361 and an extension portion 362 (extension portion). The cylindrical portion 361 has a substantially cylindrical shape having a predetermined width in the front-rear direction. The cylindrical portion 361 includes a shaft hole 361S and a pair of cut portions 361D. The shaft front end portion 35B of the secondary transfer roller 35 is inserted into the shaft hole 361S. As a result, the cylindrical portion 361 of the retaining member 36 is externally fitted to the shaft front end portion 35B. The cut portion 361D is a flat portion in which a part of the circumferential surface of the cylindrical portion 361 is cut. The pair of cut portions 361 </ b> D are arranged so as to be line symmetric about the cylindrical axis of the cylindrical portion 361.

  The extending portion 362 is a projecting piece that extends from the cylindrical portion 361 in the radial direction in the rotation of the secondary transfer roller 35. The extending portion 362 can be engaged with an insertion hole 823 </ b> S described later on the front bush 82. A base end portion of the extending portion 362 is projected from the outer peripheral portion on the front end side of the cylindrical portion 361 in the radial direction and extends with a predetermined step. And the front end side of the extension part 362 is provided with the substantially T shape by the front view seen from the front-back direction. The extending part 362 includes a gripping part 362S and an engaging protrusion 362J. The gripping part 362S is disposed on the left side and the upper side part of the distal end part of the extending part 362. The grip portion 362S is gripped by the operator when the retaining member 36 is rotated around the shaft front end portion 35B. The engagement protrusion 362J is disposed on the right side and the lower side of the tip of the extended portion 362. The engaging protrusion 362J is a protrusion protruding forward from the extending portion 362. The engagement protrusion 362J is inserted into an insertion hole 823S described later. The extended portion 362 can be elastically deformed so as to fall in the axial direction (rearward direction) of the secondary transfer roller 35 as indicated by an arrow in FIG.

  6A and 6B are perspective views of the rear bush 81 according to the present embodiment. The rear bush 81 includes a rear plate portion 810, a rear shaft support portion 811, a pressing portion 812, a rear pressed portion 813, and a rear spring locking portion 814 (FIG. 6B).

  The rear plate portion 810 is a main body portion of the rear bush 81. The rear plate portion 810 is a plate-like member that extends so as to be orthogonal to the front-rear direction. The holding portion 812 is formed at the upper end portion of the rear plate portion 810. The pressing portion 812 has a C shape with an upper end portion opened. In addition, three ribs are arranged inside the holding portion 812. The rear shaft support portion 811 is disposed adjacent to the pressing portion 812. The rear shaft support portion 811 has a cylindrical shape having a predetermined thickness along the axial direction (front-rear direction) of the secondary transfer roller 35. The rear shaft support 811 includes an opening in which a part in the circumferential direction in the rotation of the secondary transfer roller 35 is opened. A rear bearing 351 of the roller unit 35U is attached to the rear shaft support portion 811. As shown in FIG. 6A, the opening portion of the rear shaft support portion 811 communicates with the opening portion of the pressing portion 812 in the front-rear direction. Furthermore, the outer diameter and inner diameter of the rear shaft support portion 811 are set to be slightly larger than the outer diameter and inner diameter of the pressing portion 812. The openings of the rear shaft support portion 811 and the pressing portion 812 are arranged so as to face the roller unit 35U to be mounted when the roller unit 35U is mounted on the transport guide unit 8A.

  The rear pressed portion 813 is formed at the lower end portion of the rear plate portion 810 and has a convex arch shape toward the pressing portion 812 side. The secondary transfer roller 35 is separated from the belt driving roller 332 by a lever similar to the separation lever 83 (FIG. 2) pressing the rear pressed portion 813. The rear spring locking portion 814 is a cross-shaped protrusion formed on the back side of the rear pressed portion 813 (FIG. 6B). A biasing member similar to the spring member 82S described above is locked to the rear pressed portion 813.

  7A to 7C are perspective views of the front bushing 82 according to the present embodiment. The front bush 82 includes a front plate portion 820, a front shaft support portion 821, a retaining support portion 822, a storage portion 823, a front pressed portion 824 (FIG. 7B), and a front spring locking portion 825 (FIG. 7B). With.

  The front plate portion 820 is a main body portion of the front bush 82. The front plate portion 820 is a plate-like member that extends so as to be orthogonal to the front-rear direction. The retaining support portion 822 is formed at the upper end portion of the front plate portion 820. The retaining support portion 822 has a C-shape with an upper end opened. The retaining member 36 of the roller unit 35U is inserted into the retaining support portion 822. The front shaft support portion 821 is disposed adjacent to the retaining support portion 822. The front shaft support portion 821 has a cylindrical shape having a predetermined thickness along the axial direction (front-rear direction) of the secondary transfer roller 35. The front shaft support portion 821 includes an opening in which a part in the circumferential direction in the rotation of the secondary transfer roller 35 is opened. A front bearing 352 of the roller unit 35U is attached to the front shaft support portion 821. As shown in FIG. 7A, the opening portion of the front shaft support portion 821 communicates with the opening portion of the retaining support portion 822 in the front-rear direction. Further, the outer diameter and inner diameter of the front shaft support portion 821 are set slightly smaller than the outer diameter and inner diameter of the retaining support portion 822. A partition 82H having a predetermined height is disposed between the front shaft support portion 821 and the retaining support portion 822 (FIG. 7A). The openings of the front shaft support portion 821 and the retaining support portion 822 are disposed so as to face the roller unit 35U to be mounted when the roller unit 35U is mounted on the transport guide unit 8A.

  The accommodating portion 823 is connected to the front plate portion 820 so as to be disposed on the right side and above the retaining support portion 822 (FIG. 7C). The accommodating part 823 consists of three surfaces orthogonal to each other. An extension portion 362 (FIG. 5) of the retaining member 36 is accommodated inside the accommodation portion 823. The accommodating portion 823 includes an insertion hole 823S (locking portion). The insertion hole 823 </ b> S is a hole that is opened on the front side surface of the housing portion 823. The insertion protrusion 362J of the retaining member 36 is engaged with the insertion hole 823S.

  The front pressed portion 824 is formed at the lower end portion of the front plate portion 820 and has a convex arch shape toward the retaining support portion 822 side. When the separation lever 83 (FIG. 2) presses the front pressed portion 824, the secondary transfer roller 35 is separated from the belt driving roller 332. The front spring locking portion 825 (FIG. 7B) is a cross-shaped protrusion formed on the back side of the front pressed portion 824. The aforementioned spring member 82S is locked to the front spring locking portion 825.

  FIG. 8A is a front view of the rear bush 81 according to this embodiment, and FIG. 8B is a front view of the front bush 82. As described above, the rear shaft support portion 811 of the rear bush 81 supports the rear bearing 351 of the roller unit 35U. Further, the front shaft support portion 821 of the front bush 82 supports the front bearing 352 of the roller unit 35U. In this embodiment, as shown in FIGS. 8A and 8B, the opening width L2 of the opening portion of the front shaft support portion 821 of the front bush 82 is larger than the opening width L1 of the opening portion of the rear shaft support portion 811 of the rear bush 81. Is also set larger. As shown in FIG. 8B, the front shaft support portion 821 has a substantially U shape in a front view, and the rear shaft support portion 811 has a substantially C shape in a front view. In FIG. 8B, the front bearing 352 of the roller unit 35U can be inserted into the front shaft support portion 821 so as to pass through the opening of the front shaft support portion 821. On the other hand, in FIG. 8A, the rear bearing 351 of the roller unit 35U cannot be inserted into the rear shaft support portion 811 so as to pass through the opening of the rear shaft support portion 811.

  FIG. 9 is a perspective view showing a support structure of an end portion (rear end portion) in the axial direction of the secondary transfer roller 35 according to the present embodiment. 10A and 10B are perspective views illustrating a support structure of an end portion (front end portion) in the axial direction of the secondary transfer roller 35. When the surface of the secondary transfer roller 35 is scratched or foreign, or when the surface layer of the secondary transfer roller 35 is deteriorated, an image defect occurs in the toner image transferred to the sheet. Since the life of the secondary transfer roller 35 is shorter than that of the image forming apparatus 1, it is necessary to replace the secondary transfer roller 35. As described above, in this embodiment, the roller unit 35U is detachable from the transport guide unit 8A. The rear bearing 351, the front bearing 352, the retaining member 36, and the gripping roller 35H are detachable from the secondary transfer roller 35, so that these components are mounted on a new secondary transfer roller 35. It can be used continuously.

  An operator of the roller unit 35U first attaches the rear bearing 351 of the roller unit 35U to the rear bush 81 (FIG. 2). In FIG. 9, the operator enters the rear bearing 351 in front of the rear shaft support portion 811 of the rear bush 81 as indicated by an arrow D91. Then, as indicated by an arrow D92, the rear bearing 351 is mounted on the rear shaft support portion 811 along the axial direction (rear direction). As described above, the rear bearing 351 cannot be directly inserted into the rear shaft support portion 811 through the opening of the rear shaft support portion 811 along the direction parallel to the arrow D91. When the rear bearing 351 is attached to the rear shaft support portion 811, the three ribs inside the pressing portion 812 come into contact with the side surface of the rear bearing 351. For this reason, the rear bearing 351 is prevented from coming out rearward from the rear shaft support portion 811.

  At the stage where the rear bearing 351 is mounted on the rear shaft support 811, the secondary transfer roller 35 is slightly inclined with respect to the front-rear direction. That is, the front bearing 352 is still disposed at a position on the left and above the front bush 82 (FIG. 2). Next, the operator attaches the front bearing 352 (FIG. 3) to the front bush 82 along the direction orthogonal to the axial direction of the secondary transfer roller 35. Specifically, the front bearing 352 is inserted into the front shaft support portion 821 of the front bush 82 along the direction of the arrow D101 in FIG. 10A. At this time, the cylindrical portion 361 of the retaining member 36 is inserted into the retaining support portion 822 adjacent to the front shaft support portion 821. Note that the retaining support portion 822 of the front bush 82 has a substantially C shape when viewed from the front (FIG. 8A). However, since the cylindrical portion 361 of the retaining member 36 includes a pair of cut portions 361D, the cylindrical portion 361 can be inserted into the retaining support portion 822 along the direction of the arrow D101 in FIG. 10A. Since the rear bearing 351 and the front bearing 352 are supported by the rear bush 81 and the front bush 82, respectively, the secondary transfer roller 35 is rotatably supported by the transport guide unit 8A.

  Further, the operator performs a fixing operation of the retaining member 36. That is, as shown in FIG. 10A, when the front bearing 352 (FIG. 3) and the cylindrical portion 361 of the retaining member 36 are inserted into the front shaft support portion 821 and the retaining support portion 822, respectively, The extending portion 362 of the stop member 36 is rotated in the direction of the arrow D102 around the shaft front end portion 35B. At this time, the operator bends the extending portion 362 in the direction of the arrow in FIG. 5 while gripping the grip portion 362S of the retaining member 36. As a result, the engagement protrusion 362J protruding from the extended portion 362 is prevented from colliding with the front wall surface (FIG. 7A) of the accommodating portion 823 of the front bush 82. In this way, when the retaining member 36 is rotated while the extending portion 362 of the retaining member 36 is elastically deformed rearward, the extending portion 362 is accommodated inside the accommodating portion 823. When the elastic deformation of the extended portion 362 is restored by the operator, the extended portion 362 moves forward, and the engaging protrusion 362J (FIG. 5) is locked in the insertion hole 823S (FIG. 7A). And when the extension part 362 contacts the accommodating part 823, the forward movement of the roller unit 35U is restricted. Further, the engagement protrusion 362J is locked in the insertion hole 823S, whereby the rotation of the retaining member 36 around the shaft front end portion 35B is restricted. Furthermore, the backward movement of the roller unit 35U is restricted by the pressing portion 812 of the rear bush 81. This prevents the roller unit 35U from being detached from the transport guide unit 8A.

  As described above, in this embodiment, after the rear bearing 351 on the rear end side is inserted into the rear bush 81 along the axial direction, the front bearing 352 on the front end side extends along the radial direction in the rotation of the secondary transfer roller 35. Are inserted into the front bush 82. As a result, the mounting operation of the roller unit 35U can be performed smoothly and easily as compared with the case where the rear bush 81 and the front bush 82 do not include the opening. Further, in the rear bush 81, since the rear shaft support portion 811 has a C shape, the rear bush 81 can stably support the outer peripheral surface of the rear bearing 351 after the roller unit 35U is mounted. Accordingly, the rear bearing 351 is prevented from being detached from the rear bush 81. Further, since the front bearing 352 adjacent to the retaining member 36 does not need to be attached to the front bush 82 along the axial direction unlike the rear bearing 351, the front bearing 352 can be easily attached to and detached from the front bush 82. Is done.

  Furthermore, in this embodiment, the extending portion 362 of the retaining member 36 can be elastically deformed, and the engaging protrusion 362J is retained in the insertion hole 823S, so that the retaining operation of the retaining member 36 is facilitated. Realized. Note that when the roller unit 35U is detached from the transport guide unit 8A, the operator can easily remove the roller unit 35U by a procedure reverse to the above. At this time, the necessity to remove a plurality of members other than the roller unit 35U from the conveyance guide unit 8A in advance is reduced.

  The transfer device according to the embodiment of the present disclosure and the image forming apparatus 1 including the transfer device have been described above. According to the above configuration, the transfer device and the image forming apparatus 1 in which the detachability of the secondary transfer roller 35 is improved are provided. As a result, even when the life of the secondary transfer roller 35 is shorter than the life of the image forming apparatus 1, the replacement of the secondary transfer roller 35 is easily realized. Further, the time during which use of the image forming apparatus 1 is interrupted is reduced with the replacement of the secondary transfer roller 35. In addition, this invention is not limited to these, For example, the following modified embodiment is employable.

  (1) In the above-described embodiment, the conveyance guide unit 8A has been described as an aspect that functions as a casing of the secondary transfer roller 35, but the present invention is not limited to this. In another modified embodiment, the image forming apparatus 1 may be provided with another housing on which the roller unit 35U is mounted, in addition to the conveyance guide unit 8A.

  (2) In the above embodiment, the embodiment has been described in which the retaining member 36 is provided with the engaging protrusion 362J and the housing portion 823 of the front bush 82 is provided with the insertion hole 823S, but the present invention is not limited thereto. It is not something. In another modified embodiment, an insertion hole may be formed in the extended portion 362 of the retaining member 36, and an engaging projection may be provided in the housing portion 823.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Apparatus main body 10R Right wall 32 Image forming part 33 Intermediate transfer unit 35 Secondary transfer roller (transfer roller)
351 Rear bearing (bearing)
352 Front bearing (bearing)
35A Shaft rear end (shaft)
35B Shaft front end (shaft)
35H Gripping roller 35U Roller unit 36 Retaining member 361 Cylindrical portion 361D Cut portion 361S Shaft hole 362 Extension portion 362J Engagement protrusion (protrusion portion)
362S Grip part 51 Registration roller pair 51A Registration roller 8 Double-sided conveyance unit 81 Rear bush (support member)
810 Rear plate portion 811 Rear shaft support portion 812 Holding portion 813 Rear pressed portion 814 Rear spring locking portion 82 Front bush (support member)
820 Front plate part 821 Front shaft support part 822 Retaining prevention support part 823 Storage part 823S Insertion hole (locking part, hole part)
824 Front pressed portion 825 Front spring locking portion 82S Spring member 83 Separation lever 8A Conveyance guide unit (housing)
8B cover unit

Claims (7)

A housing,
A transfer roller for transferring the developer image onto a sheet, which is in contact with an image carrier that carries a developer image on its surface, is rotated, and is mounted on the housing along a mounting direction that intersects the axial direction of the rotation A roller unit to be
Have
The transfer roller includes a shaft portion protruding from both end sides in the axial direction,
The roller unit is
A pair of bearings mounted on the shaft at both ends of the transfer roller;
A retaining member that is externally fitted to the shaft portion so as to be adjacent to the bearing on one end side in the axial direction;
With
The housing includes a pair of support members that respectively support outer peripheral surfaces of the pair of bearings,
Each of the pair of support members includes an opening in which a part of the rotation in the circumferential direction is opened, and includes a cylindrical shape having a predetermined thickness along the axial direction.
The support member on one end side in the axial direction includes a locking portion,
When the roller unit is mounted on the housing, after the bearing is supported by the support member, when the retaining member is rotated around the shaft portion, the retaining member is locked. A transfer device that is locked to a portion. The retaining member is
A cylindrical portion that is externally fitted to the shaft portion;
An extending portion extending from the cylindrical portion in the radial direction in the rotation and engageable with the locking portion;
With
The transfer device according to claim 1, wherein the extending portion is elastically deformable so as to fall in the axial direction. The locking portion is a hole opened in the support member,
The extending portion of the retaining member includes a protrusion,
When the roller unit is mounted on the housing, the extension portion is elastically deformed to the other end side in the axial direction, and the retaining member is rotated around the shaft portion. The transfer device according to claim 2, wherein when the elastic deformation of the portion is restored, the protruding portion is locked in the hole portion.   The transfer device according to claim 3, wherein the extended portion of the retaining member includes a grip portion that is gripped in the rotation around the shaft portion.   The opening width of the opening of the support member on one end side in the axial direction is set larger than the opening width of the opening of the support member on the other end side in the axial direction. Item 5. The transfer device according to any one of Items 1 to 4.   After the bearing on the other end side in the axial direction of the roller unit is mounted on the support member along the axial direction, the bearing on one end side in the axial direction extends along a direction orthogonal to the axial direction. The transfer device according to claim 5, wherein the roller unit is supported by the pair of support members by being mounted on the support member. A transfer apparatus according to any one of claims 1 to 6;
The image carrier carrying a developer image on the surface;
An image forming apparatus comprising:

Images