JP4289287B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile machine.

  As an electrophotographic image forming apparatus, for example, a photosensitive drum is used as an image carrier, the surface is charged and exposed to form an electrostatic latent image, and toner is attached to the electrostatic latent image. An image forming apparatus that forms a visible image and transfers the image onto a sheet is known. In such an image forming process, each process is performed while the paper is being transported. However, troubles such as paper jamming may occur during the transport of the paper. Therefore, an opening / closing cover is provided in the apparatus main body, and the jammed sheet in the sheet conveying path can be removed by opening the opening / closing cover. When a pair of driving rollers and driven rollers are provided as conveying rollers in the paper conveying path, a driving roller is provided on the apparatus body side, and a driven roller is provided on the opening and closing cover side. The driven roller is separated from the drive roller in conjunction with the opening operation, and the paper in the paper transport path can be easily removed.

As a mechanism for enabling contact between the driving roller and the driven roller in this manner, for example, in Patent Document 1, the driven roller can be moved forward and backward with respect to the driving roller by an eccentric cam fixed to the spindle of the driven roller. The point which was done is indicated. In Patent Document 2, the driven roller held by the paper discharge frame is urged by the urging means to the driving roller when the paper discharge frame is closed, and the urging force by the urging means is released when the paper discharge frame is opened. The point which was made to do is indicated.
JP-A-7-237774 Japanese Patent Laid-Open No. 2003-300643

  The drive roller and the driven roller can be brought into contact with and separated from each other so that the paper can be easily removed in the case of a paper jam or the like. However, when the driven roller becomes movable with respect to the drive roller, the drive roller The positioning of the driven roller and the pressure contact force with respect to the ink become unstable, and the sheet is likely to be skewed. In particular, when a follower roller is attached to the open / close cover, if the play occurs in the open / close cover, the follower roller is not accurately positioned with respect to the drive roller, and the sheet is skewed.

  SUMMARY OF THE INVENTION Accordingly, the present invention provides an image forming apparatus that can accurately position a driven roller with respect to a driving roller and can easily open and close the cover even when a driven roller is provided. It is intended.

An image forming apparatus according to the present invention includes a drive roller for conveying a paper supported by a shaft support member on the apparatus main body side, a cover attached to the apparatus main body so as to be openable and closable, and a support provided on an inner surface of the cover. And a driven roller supported by the member. In the image forming apparatus in which the driven roller is set in pressure contact with the drive roller in the closed state of the cover, the support member idles the shaft of the driven roller. The support member has a support hole to be fitted and supported, is attached to the cover so as to be able to advance and retreat, and is urged by a urging member, and the shaft support member is a fit that supports and supports the shaft of the driven roller A shaft of the driven roller is pivotally supported by the fitting portion in the closed state of the cover, and the driving roller is biased by the biasing force of the biasing member. Come to be selfish pressed, the the supporting hole, the shaft of the driven roller are movable accommodation space is formed in a direction deviating from the fitting portion, the driven in conjunction with the opening operation of the cover The roller shaft is in contact with a slope formed on the inner peripheral surface of the support hole and guided in a direction away from the fitting portion . Further, the cover is provided with a guide member that guides the support member in the advancing / retreating direction, and a restricting portion that restricts the movement of the support member by the urging force of the urging member is formed at the tip of the guide member. It is characterized by being.

  By having the configuration as described above, a fitting portion for fitting and supporting the shaft of the driven roller is provided on the shaft support member of the driving roller, and the shaft of the driven roller is loosely fitted in the support hole of the support member. Therefore, the shaft of the driven roller is pivotally supported by the shaft support member on which the drive roller is pivotally supported, and the driven roller is always positioned accurately with respect to the drive roller. Further, since the support member is attached to the cover so as to be able to advance and retreat and is urged by the urging member, the driven roller is pressed toward the drive roller together with the support member while being pivotally supported by the fitting portion. A stable pressure contact state can be realized between the two.

  In addition, the support hole is formed with an accommodation space in which the shaft of the driven roller can move in a direction away from the fitting portion in conjunction with the opening operation of the cover, so that the cover opens and the driven roller moves from the fitting portion. Since it moves to the accommodation space when it comes off, the opening operation of the cover can be easily performed.

  In addition, a guide surface that guides the shaft of the driven roller in a direction away from the fitting portion is formed on the inner peripheral surface that defines the accommodation space of the support hole, so that the shaft of the driven roller can be easily moved from the fitting portion. As a result, the cover can be opened reliably.

  Also, the cover member is provided with a guide member that guides the support member in the advancing and retracting direction, and a restricting portion that restricts the movement of the support member by the urging force of the urging member is formed at the front end of the guide member, so that the support member advances and retracts. Can be performed stably, and the opening / closing operation of the cover can be performed more reliably.

  Hereinafter, embodiments according to the present invention will be described in detail. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

    FIG. 1 is a schematic cross-sectional view of the entire image forming apparatus according to the present invention. A paper discharge tray 10 is provided in the upper part of the image forming apparatus 1, and a recording unit 2 and a paper feeding unit 3 are arranged in the lower part thereof.

  In the paper feed unit 3, a paper feed cassette 11 is arranged, and a plurality of sheets of a predetermined size are stacked on the flapper 12. A pickup roller 13 is disposed at the right end of the paper feed cassette 11. The flapper 12 is urged upward by a spring member (not shown) so that the upper surface of the stacked paper comes into pressure contact with the pickup roller 13. When the pickup roller 13 is rotationally driven in this state, the sheets are fed one by one to the sheet conveyance path by the frictional force.

  The fed paper is first conveyed to the recording unit 2 by the feed roller 14 and the press roller 15. The recording unit 2 includes a developing device 16, a cleaning mechanism 17, a corona charger 18, a photosensitive drum 19, a transfer roller 20, a laser scanner unit 21, and a fixing roller 22 for recording on the conveyed paper. . The cleaning mechanism 17 cleans the surface of the photosensitive drum 19 by capturing foreign particles such as residual toner and paper dust attached to the surface of the photosensitive drum 19 after the transfer with a cleaning roller. The corona charger 18 uniformly charges the surface of the photosensitive drum 19 by corona discharge from the discharge wire. An electrostatic latent image is formed on the uniformly charged photosensitive drum 19 by exposing the photosensitive drum 19 in accordance with an image recording signal. Then, the toner in the developing device 16 is transferred to the electrostatic latent image formed on the photosensitive drum 19 to visualize the electrostatic latent image. The transfer roller 20 is installed at a position facing the photosensitive drum 19 with the paper interposed therebetween, and a toner image formed on the surface of the photosensitive drum 19 is transferred to the paper when a predetermined voltage is applied. The transferred toner image is sandwiched between the fixing roller 22 and the press roller 23 and heated and pressed to be fixed on the paper. The fixed sheet is sandwiched between the sheet discharge roller 24 and the press roller 25 and is carried out to the sheet discharge tray 10.

  Further, a manual paper feed mechanism and a reverse conveyance mechanism are provided on the side surface of the apparatus main body, and when performing manual paper feed, the side cover 26 is opened and the paper is inserted into the paper feed roller 27. . The inserted paper is conveyed to the feed roller 14 and the press roller 15 by the paper feed roller 27 and recording operation is performed. Also, in the case of reverse conveyance, the paper recorded on one side is once sandwiched between the paper discharge roller 24 and the press roller 25 and carried out, and the paper discharge roller 24 is reversely rotated to enter the reverse conveyance path. The sheet is conveyed and conveyed downward by two pairs of conveyance rollers, that is, a feed roller 28 and a press roller 29, a feed roller 30 and a press roller 31. Then, the sheet is conveyed again to the feed roller 14 and the press roller 15 and a recording operation is performed on the other side, and recording is performed on both sides of the sheet.

  FIG. 2 is a schematic perspective view showing a state where a feed roller 14 as a driving roller and a press roller 15 as a driven roller are separated from each other. In FIG. 2, the opening / closing cover 100 is rotatably attached to a rotating shaft 101 provided in the apparatus main body, and the opening / closing cover 100 is opened / closed together with the reverse conveying mechanism of FIG. In addition, the paper conveyance path to the press roller 15 and the transfer roller 20 is opened and closed. Since the feed roller 14 is attached to the apparatus main body side and the press roller 15 is attached to the opening / closing cover 100, the press roller 15 is separated from the feed roller 14 in conjunction with the opening operation of the opening / closing cover 100. become.

  Both ends of the shaft 14a of the feed roller 14 are supported by a shaft support member 40, and the shaft support member 40 is fixed to a mounting base 32 of the main body frame. Further, the shaft 15a of the press roller 15 is supported by loosely fitting both ends of the shaft 15a into the support holes 51 of the support member 50, and the support member 50 can be moved forward and backward with respect to the inner surface of the opening / closing cover 100 as will be described later. Is provided.

  FIG. 3 is a schematic view seen from the side in FIG. The shaft 14 a of the feed roller 14 is inserted into a circular shaft hole 41 formed in the shaft support member 40. A fitting portion 42 is formed adjacent to the shaft hole 41. The fitting portion 42 is formed in a U-shaped cross section, and the vertical width of the inner surface is set to be substantially the same as or slightly larger than the diameter of the shaft 15 a of the press roller 15. In addition, the surface that bisects the vertical width of the inner surface of the fitting portion 42 is set so as to pass substantially the center of the shaft hole 41. The protrusion 43 constituting the upper portion of the fitting portion 42 is formed so as to bend upward from the middle, and serves as a guide for guiding the shaft 15 a of the press roller 15.

  The shaft 15 a of the press roller 15 is loosely fitted in a support hole 51 formed in the support member 50 in a substantially rectangular shape. FIG. 4 is an exploded view showing a state in which the support member 50 is attached to the opening / closing cover 100. The support member 50 includes a rectangular base portion 52 in which a support hole 51 is formed, and an insertion portion 53 attached to the opening / closing cover so as to protrude in a substantially vertical direction. The distal end portion of the insertion portion 53 is inserted into the insertion hole 60 of the opening / closing cover, and the support member 50 is mounted so as to be able to advance and retract in the insertion direction. An urging spring 54 is wound around the insertion portion 53, and presses against the base portion 52 to urge the support member 50 in a direction away from the opening / closing cover 100. A pair of guide members 61 are erected on the opening / closing cover 100 so as to sandwich the base portion 52. Each guide member 61 is linearly extended along the advancing / retreating direction of the support member 50, and a restricting portion 62 protruding inwardly in a hook shape is formed at the tip portion thereof. Therefore, when the base portion 52 is pressed by the urging spring 54, the base portion 52 moves along the guide member 61 and is held in a state of being in contact with the restricting portion 62 of the guide member 61. .

  FIG. 5 to FIG. 10 are schematic side views showing a state from the closed state to the opened state of the opening / closing cover 100. FIG. 5 shows a state in which the open / close cover 100 is closed, in which the press roller 15 is in pressure contact with the feed roller 14. The shaft 15 a of the press roller 15 is fitted and supported between the upper and lower surfaces of the inner surface of the fitting portion 42, and the base portion 52 of the support member 50 is pressed toward the feed roller 14 by the urging spring 54. As a result, the abutting portion 51 a formed on the inner surface of the support hole 51 presses the shaft 15 a, and the press roller 15 is pressed against the feed roller 14. When the press roller 15 is in pressure contact with the feed roller 14, the press roller 15 is pushed back so that the support member 50 is held at a position retracted to the opening / closing cover side against the biasing force of the biasing spring 54. become. Therefore, the base portion 52 of the support member 50 is in a state of being separated from the restricting portion 62.

  In this state, the shaft 15 a of the press roller 15 is supported at three points, that is, the upper and lower surfaces of the fitting portion 42 and the contact portion 51 a of the support hole 51, and thus is held in a stable state. In addition, since the surface that bisects the vertical width of the inner surface of the fitting portion 42 is accurately set so as to pass through the center of the shaft 14a of the feed roller 14, the shaft 15a pivotally supported by the fitting portion 42 and The positional relationship with the shaft 14a is accurately positioned. Therefore, the positioning of the press roller 15 with respect to the feed roller 14 is accurately performed, and the sheet conveyance can be stably performed.

  FIG. 6 shows a state in which the opening / closing cover 100 is rotated in the opening direction (clockwise) from the state of FIG. In this state, the support member 50 also rotates together with the opening / closing cover 100, and moves in a diagonally upward right direction in FIG. Therefore, the support member 50 moves toward the feed roller 14 by the urging force of the urging spring 54, but the base portion 52 of the support member 50 comes into contact with the restriction portion 62 of the guide member 61 and is restricted. become. Accordingly, the contact portion 51 a of the support hole 51 is separated from the shaft 15 a of the press roller 15, and the shaft 15 a is released from the pressing of the biasing spring 54. At this time, the shaft 15a remains pivotally supported by the fitting portion 42, but is separated from the inner peripheral surface of the support hole 51.

  FIG. 7 shows a state in which the opening / closing cover 100 is further rotated in the opening direction from the state of FIG. An accommodation space 51b is formed below the abutment portion 51a of the support hole 51 so that the shaft 15a of the press roller 15 can move in a direction away from the fitting portion 42. In the accommodation space 51b, the inner peripheral surface below the contact portion 51a extends to the opening / closing cover 100 side, and further, a downwardly inclined surface portion 51c corresponding to the guide surface is formed on the feed roller 14 side. In the state of FIG. 6, the shaft 15a is loosely fitted in the support hole 51. However, when the support member 50 is further rotated in the upper right direction by the rotation of the opening / closing cover 100, the inclined surface portion 51c is attached to the shaft 15a. Come into contact. Therefore, the shaft 15a is pressed by the slope portion 51c and moves in a direction away from the fitting portion 42, and moves in the accommodation space 51b by the slope portion 51c and obliquely downward to the right. In this state, since the projecting portion 43 is formed to bend upward, the shaft 15a moves away from the upper surface of the fitting portion 42 in order to move in the diagonally downward right direction, but the inclined portion 51c and the fitting portion 42 It will be in the state which contacted the lower surface of the inner surface, and will move to the opening-and-closing cover side.

  FIG. 8 shows a state in which the opening / closing cover 100 is further rotated in the opening direction from the state of FIG. Since the support member 50 moves further obliquely upward to the right from the state shown in FIG. 7, the shaft 15a moves together with the support member 50 in contact with the slope portion 15c and the bottom surface of the accommodation space 15b. At this time, since the protrusion 43 that defines the upper portion of the fitting portion 42 is bent upward, the shaft 15 a can be detached from the fitting portion 42 without colliding with the protrusion 43. 9 and 10 sequentially show the state in which the opening / closing cover 100 rotates in the opening direction, but the shaft 15a held in the accommodation space 51b of the support hole 51 is diagonally right along the protruding portion 43. Since the shaft 15a moves upward, the shaft 15a can be removed smoothly without bending the protrusion 43. Further, in the case of the closing operation of the opening / closing cover 100, the shaft 15a is smoothly supported by the fitting portion 42 and pressed by the urging spring 54 by reversely moving from FIG. 10 to FIG. Therefore, the opening / closing operation of the opening / closing cover 100 can be easily performed.

  As described above, the shaft 15a can be fitted to the fitting portion 42 without bending the protruding portion 43, so that the rigidity of the protruding portion 43 can be increased and the shaft 15a can be stably supported. Become.

  The shape of the accommodation space 51b is not limited to the shape described above as long as the shaft 15a can move in a direction away from the fitting portion 42.

It is a schematic sectional drawing regarding embodiment which concerns on this invention. It is a schematic perspective view of the state which separated between the feed roller and the press roller. It is the schematic seen from the side in FIG. It is an exploded view which shows the attachment state to the opening / closing cover of a supporting member. It is a schematic side view which shows the state which the opening / closing cover closed. It is a schematic side view which shows the state rotated in the opening direction of the opening / closing cover. It is a schematic side view which shows the state rotated in the opening direction of the opening / closing cover. It is a schematic side view which shows the state rotated in the opening direction of the opening / closing cover. It is a schematic side view which shows the state rotated in the opening direction of the opening / closing cover. It is a schematic side view which shows the state rotated in the opening direction of the opening / closing cover.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Recording part 3 Paper feeding part
14 Feed roller
14a shaft
15 Press roller
15a shaft
40 Shaft support member
41 Shaft hole
42 Insertion
43 Protrusion
50 Support member
51 Support hole
51a Contact part
51b Containment space
51c Slope
54 Biasing spring
61 Guide members
62 Regulatory Department
100 Cover
101 Rotation axis

Claims (2)

A paper conveying drive roller supported by a shaft support member on the apparatus main body side, a cover attached to the apparatus main body so as to be openable and closable, and a driven roller supported by a support member provided on the inner surface of the cover. And the support member has a support hole that loosely fits and supports the shaft of the driven roller in an image forming apparatus in which the driven roller is set in pressure contact with the drive roller when the cover is closed. And is attached to the cover so as to be able to advance and retreat, and is urged by a urging member, and the shaft support member has a fitting portion for fitting and supporting the shaft of the driven roller. shaft rollers by the urging force of the urging member while being pivotally supported by the fitting portion in the closed state of the cover will be pressed against the drive roller The support hole is formed with an accommodation space in which the shaft of the driven roller can move in a direction away from the fitting portion, and the shaft of the driven roller is connected to the support hole in conjunction with the opening operation of the cover. An image forming apparatus, wherein the image forming apparatus is guided in a direction coming in contact with a slope portion formed on an inner peripheral surface and coming off from the fitting portion . The cover is provided with a guide member for guiding the support member in the advancing / retreating direction, and a restricting portion for restricting the movement of the support member by the urging force of the urging member is formed at the tip of the guide member. The image forming apparatus according to claim 1, wherein:

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