JP2011102160A - Sheet post-treatment apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet post-treatment apparatus improving alignment accuracy in sheet stacking by stabilizing a way of applying conveyance force to shifted recording sheets, and an image forming apparatus. <P>SOLUTION: The sheet post-treatment apparatus 200 includes a shift means 400 moving the image-formed recording sheets P conveyed by sheet conveying means 201, 204, in a shift direction orthogonal to a sheet conveying direction Y; a pair of delivery rollers 206 arranged downstream in the sheet conveying direction from the shift means and delivering the recording sheets moved in the shift direction by the shift means, to a sheet stacking part 203; and a moving means 500 moving one roller 224 out of the pair of delivery rollers by the same amount in the same direction as the shift direction by the shift means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sheet post-processing apparatus that performs post-processing of an image-formed recording sheet, and an image forming apparatus including the apparatus.

  As a sheet post-processing apparatus that performs post-processing of recording sheets discharged from the image forming apparatus main body, a stapling process that bundles a plurality of recording sheets into one by a stapling mechanism, and a predetermined number of recording sheets discharged to a sheet stacking unit In order to divide the recording sheet into two, a shift process is known in which a recording sheet is moved in the sheet width direction orthogonal to the sheet discharge direction (hereinafter referred to as “shift movement”). As a shift movement method, there are a sheet width direction as a shift direction, and a sheet stacking unit is moved in this shift direction, and a roller pair for conveying a recording sheet as described in Patent Document 1 is shifted. .

  Some sheet post-processing apparatuses include a shift roller pair for shifting a recording sheet, and a discharge roller pair on the downstream side of the roller pair in the sheet conveying direction. This is because the conveyance force is applied to the recording sheet when the sheet conveyance path is long. When performing shift processing in such a configuration, the recording sheet is moved in the shift direction with the recording sheet held between the pair of shift rollers before being discharged to the sheet stacking unit. When the movement in the positive direction and the opposite direction is set as the negative direction, the initial position of the discharge roller pair is a shift movement in any direction from the initial position when the recording sheet is sent from the image forming apparatus main body. In many cases, the recording sheet is arranged so as to come to the center position in the width direction of the recording sheet. Further, when the sheet post-processing apparatus has a stapling function, before discharging the recording sheet to the sheet stacking unit, the sheet post-processing apparatus may be nipped by the shift roller pair and shifted to a stapling position.

  For this reason, when the shifted recording sheet is sandwiched by the discharge roller pair after the shift movement, the recording sheet is sandwiched by the discharge roller pair at a position shifted from the center position of the discharge roller pair by the shift movement. As a result, the feeding force varies, and this may cause a reduction in alignment accuracy when recording sheets are stacked.

  SUMMARY OF THE INVENTION An object of the present invention is to propose a sheet post-processing apparatus and an image forming apparatus that stabilize the manner in which a conveying force is applied to a shifted recording sheet and improve alignment accuracy when stacking sheets. .

  A sheet post-processing apparatus according to the present invention is arranged with a shift unit that moves a recording sheet after image formation conveyed by a conveyance unit in a shift direction orthogonal to the sheet conveyance direction, and downstream of the shift unit in the sheet conveyance direction. A discharge roller pair for discharging the recording sheet moved in the shift direction by the shift means to the sheet stacking unit, and a moving means for moving one roller of the discharge roller pair in the same direction as the shift direction by the shift means. It is characterized by having.

  In the sheet post-processing apparatus according to the present invention, when the moving unit divides the recording sheets after image formation into a plurality of sheets, the moving unit operates only once for one section and moves one roller in the shift direction. It is characterized in that it is held in a fixed position.

  In the sheet post-processing apparatus according to the present invention, a plurality of the other rollers of the discharge roller pair are arranged at positions facing one of the moved rollers when the one roller moves in the shift direction. Yes.

  An image forming apparatus according to the present invention includes an image reading unit and an image forming unit, and the sheet post-processing device is disposed between the image reading unit and the image forming unit.

  According to the present invention, one roller of the discharge roller pair is moved by the same amount in the same direction as the shift direction by the shift amount of the recording sheet in the shift direction by the shift means. Thus, the conveyance force applied to the recording sheet can be made uniform, and the paper alignment property can be improved.

1 is a schematic diagram illustrating a configuration example of an image forming apparatus including a sheet post-processing process according to the present invention. It is an enlarged view which shows schematic structure of the sheet | seat post-processing process which concerns on this invention. It is a perspective view which shows schematic structure of a shift means. FIG. 4 is an enlarged perspective view showing a schematic configuration and a shift operation state of a shift roller pair and a discharge roller pair. It is a perspective view which shows schematic structure of a moving means. FIG. 6 is a plan view showing a positional relationship between a shift roller pair, a discharge roller pair, and a recording sheet during a shift operation. FIG. 7 is a plan view illustrating a positional relationship between a shift roller pair, a discharge roller pair, and a recording sheet during a shift operation in a direction opposite to that in FIG. 6.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the overall configuration of the image forming apparatus will be described, and then the characteristic configuration of the sheet post-processing apparatus will be described.

  FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus includes an image forming unit 100, a sheet post-processing device 200, and an image reading unit 300. The sheet post-processing apparatus 200 is disposed between the image forming unit 100 and the image reading unit 300. The image reading unit 300 is a known unit that optically scans an original set on a contact glass and reads an image on the original.

  In this embodiment, an indirect transfer type tandem color image forming apparatus is described as an example of the image forming apparatus. However, the image forming apparatus is not limited to such an image forming apparatus capable of forming a tandem type or a color image. It may be a monochrome one that forms. The image forming unit 100 is disposed inside the image forming apparatus main body 101 and includes image forming stations 111Y, 111M, 111C, and 111K for four colors of yellow, magenta, cyan, and black. Below each imaging station, an optical writing unit 112 is disposed adjacent to the imaging station 111. A paper feeding unit 120 is disposed below the optical writing unit 112. An intermediate transfer belt 113 serving as an intermediate transfer member is disposed above each image forming station, and a fixing unit 150 is disposed at the upper right of the intermediate transfer belt 113.

  Each image forming station 111 includes a photosensitive drum for each color of yellow, magenta, cyan, and black, and a charging unit, a developing unit, a primary transfer unit, a cleaning unit, and a cleaning unit arranged along the outer periphery of the photosensitive drum. A neutralization unit, an intermediate transfer belt 113 that intermediately transfers an image formed on each photosensitive drum by a primary transfer unit, and an optical writing unit (not shown) that writes an image for each color on the photosensitive drum are provided around the periphery. Yes.

  The intermediate transfer belt 113 is rotatably supported by a plurality of rollers. One of the plurality of rollers 114 is disposed opposite to the secondary transfer roller 115 with the intermediate transfer belt 113 interposed therebetween, and constitutes a secondary transfer unit 140 together with the secondary transfer roller 115. In the secondary transfer unit 140, the image transferred onto the intermediate transfer belt 113 is secondarily transferred onto the recording sheet P. Reference numeral 116 denotes a toner container which is arranged to be replaceable and replenishes toner to the developing unit of each image forming station 111. The image forming process by the indirect transfer type tandem color image forming apparatus is well known and will not be described in detail.

  A conveyance path 130 for conveying the recording sheet P to the secondary transfer unit 140 and the fixing unit 150 is disposed between the paper feeding unit 120 and the fixing unit 150. The paper feed unit 120 includes a paper feed tray 121, a pickup roller 122, and a transport roller 123, and sends the recording sheet P picked up from the paper feed tray 121 upward along the transport path 130. The sent recording sheet P is transferred with the toner image by the secondary transfer unit 140 and sent to the fixing unit 150. The fixing unit 150 includes a fixing roller and a pressure roller, and heat and pressure are applied in a process in which the recording sheet P passes through a fixing nip formed between the two, so that the toner is fixed to the recording sheet P. belongs to.

  A discharge conveyance path 160 and a duplex conveyance path 170 are provided downstream of the fixing unit 150 in the sheet conveyance direction Y. The discharge conveyance path 160 is disposed between the fixing unit 150 and the sheet post-processing apparatus 200, and conveys the recording sheet P after image formation on which the image is fixed by the fixing unit 150 toward the sheet post-processing apparatus 200. To do. The double-sided conveyance path 170 reverses the recording sheet P having an image fixed on one side during double-sided printing, and conveys the recording sheet P to the secondary fixing unit 140. A branch claw 161 provided at a branch portion of the discharge conveyance path 160 and the double-side conveyance path 170 conveys the recording sheet P that has passed through the fixing unit 150 to either the discharge conveyance path 160 or the double-side conveyance path 170. Are switched. A pair of branch conveyance rollers 162 is disposed upstream of the branch claw 161 in the sheet conveyance direction Y, and applies a conveyance force to the recording sheet P that has passed through the fixing unit 150.

  The sheet post-processing apparatus 200 can be attached to and detached from the image forming apparatus main body 101. When the sheet post-processing apparatus 200 is mounted, the sheet post-processing apparatus 200 is disposed inside a hollow portion 101A formed in the image forming apparatus main body 101, and is conveyed from the discharge conveyance path 160. The formed recording sheet P is subjected to predetermined post-processing and is stacked on a stacking tray 203 serving as a sheet stacking unit located on the most downstream side in the sheet conveyance direction Y. Details will be described later.

  In the image forming apparatus configured as described above, image data used for writing is generated based on document data read by the image reading unit 300 or print data transferred from an external computer or the like. Based on this, optical writing is performed from the optical writing unit 112 to each photosensitive drum. In each image forming station, the image formed for each color is sequentially transferred to the intermediate transfer belt 113, and a color image in which four color images are superimposed on the intermediate transfer belt 113 is formed.

  The recording sheet P is fed from the paper feed tray 121 according to image formation. The recording sheet P is temporarily stopped at a registration roller position (not shown) immediately before the secondary transfer unit 140, sent in time with the leading edge of the image on the intermediate transfer belt 113, and secondarily transferred by the secondary transfer unit 140. Sent to the fixing unit 150.

  The recording sheet P on which the image is fixed by the fixing unit 150 is guided to the discharge conveyance path 160 side by the switching operation of the branch claw 161 in the case of single-sided printing and after double-sided printing of double-sided printing. By the switching operation, the paper is guided to the double-sided conveyance path 170 side after single-sided printing. The recording sheet P guided to the double-sided conveyance path 170 is reversed and sent again to the secondary transfer unit 140, and after the image is fixed on the other side, it is conveyed to the discharge conveyance path 160 side. The recording sheet P transported to the discharge transport path 160 side is transported to the sheet post-processing device 200 and is subjected to a predetermined post-processing by the sheet post-processing device 200 or to the stacking tray 203 when no post-processing is performed. Discharged.

  Next, the configuration of the sheet post-processing apparatus 200 will be described with reference to FIG. FIG. 2 is a diagram mainly showing a schematic configuration of the sheet post-processing apparatus 200. The sheet post-processing apparatus 200 includes an inlet roller pair 201, a discharge conveyance path 202, a shift conveyance roller pair 204, a staple tray 219, a hitting roller 211, a return roller 214, a rear end reference fence 220, a jogger fence (alignment plate) 212, a discharge It is mainly composed of a roller pair 206 and a stacking tray 203.

  On the recording sheet receiving side 200 </ b> A of the sheet post-processing apparatus 200, an inlet roller pair 201 that receives the recording sheet P conveyed from the discharge conveyance path 160 of the image forming apparatus main body 101 and a shift conveying roller pair 204 that receives the received recording sheet P. A discharge conveyance path 202 that guides to the side is provided.

  The entrance roller pair 201 includes a driving roller and a driven roller that is driven by the driving roller. The shift conveyance roller pair 204 is disposed at the most downstream end of the discharge conveyance path 202, and includes a shift drive roller 204A and a shift driven roller 204B that is driven by the rotation of the shift drive roller 204A. The driving roller 201A and the shift driving roller 204A are connected to an inlet motor 216 configured by a stepping motor as a driving unit via a belt and a pulley, and the inlet motor 216 is driven to sandwich the recording sheet P. Then, the recording sheet P is conveyed along the discharge conveyance path 202.

  An inlet sensor 207 is disposed in the discharge conveyance path 202 located between the inlet roller pair 201 and the shift conveyance roller pair 204, and detects the leading edge and the trailing edge of the recording sheet P, and the leading edge and trailing edge of the detected recording sheet P. The timing at which the sheet processing is performed is determined based on the detection timing and the number of drive steps of the discharge motor 217 configured by an inlet motor 216 and a stepping motor serving as a discharge drive means described later. In this embodiment, the inlet roller pair 201 and the shift conveyance roller pair 204 provided along the discharge conveyance path 202 function as conveyance means.

  The discharging operation by the sheet post-processing apparatus 200 includes a normal mode in which the recording sheet P after image formation is discharged to the stacking toilet 203 without post-processing, and a shift direction W orthogonal to the sheet conveyance direction after image formation. (See FIG. 3), a shift mode for shifting, that is, shifting and discharging to the stacking tray 203, and a stapling mode for binding and discharging a plurality of recording sheets P every predetermined number of sheets are provided. Since the present invention solves the problem of moving the recording sheet P in the shift direction W, the description regarding the normal mode is omitted.

As shown in FIG. 3, the sheet post-processing apparatus 200 includes a shift unit 400 that moves the recording sheet P after image formation conveyed by the conveyance unit in the shift direction W. In the present embodiment, the shift unit 400 is applied to the shift conveyance roller pair 204. Hereinafter, the configuration and operation will be described separately for the shift mode and the staple mode.
(Shift mode)
The shift mode is a mode in which when the recording sheet P is discharged, the discharge position of the recording sheet P is shifted in the sheet width direction W every predetermined number of sheets, and the recording sheet P is sorted by this shift, and when the shift mode is set. The shift means 400 is configured to operate.

  In this embodiment, the shift driving roller 204A is supported as two rollers on a shaft 222A extending in the shift direction W, and the shaft 222A is rotationally driven by an inlet motor 216, whereby the recording sheet P is moved in the sheet conveying direction Y. Rotate in the direction of transport to.

  The shift means 400 includes a shift motor 401, a gear portion 402 rotated by the shift motor 401, and a link portion 403 that moves the shaft 222A in the shift direction W by the rotation of the gear portion 402. The shift motor 401 is connected to the shaft 222A via the gear portion 402 and the link portion 403, and moves the shaft 222A in the shift direction W when the shift motor 401 rotates by a certain amount. The shift driving roller 204A is configured to be movable, for example, 10 mm from one position to the other side in the shift direction W indicated by a two-dot chain line in FIGS. 6 and 7 and 20 mm on both sides. This shift movement amount can be changed to an arbitrary shift amount by making the shift motor 401 a motor that can control the movement amount, such as a step motor. The shift movement amount is set such that the recording sheets P can be distinguished when the recording sheets P are discharged and stacked on the stacking tray 203.

  As shown in FIG. 3, the shift driven roller 204B is disposed as two rollers on a support shaft 222B disposed in parallel with the shaft 222A. Each shift driven roller 204B is rotatably supported by the support shaft 222B so as to elastically contact each shift drive roller 204A, and forms a nip portion with each shift drive roller 204A.

  These shift driven rollers 204B rotatably supported by the support shaft 222B are elastically urged toward the center of the support shaft 222B by a spring 223 disposed beside each shift follower roller 204B, and the shift drive roller 204A. After moving in the shift direction W, the self-return to the original position is configured.

  With such a configuration, the shift conveyance roller pair 204 is movable in the shift direction W when the shaft 222 </ b> A is reciprocated in the shift direction W by the shift motor 401. That is, when sorting the recording sheets P in the shift mode, the shift motor 401 is driven in a state where the recording sheet P is sandwiched between the shift driving roller 204A and the shift driven roller 204Bs, and the shift conveying roller pair 204 is moved every predetermined number of sheets. By moving the recording sheet P in the shift direction W (sheet width direction), the recording sheet P is shifted by the amount moved in the shift direction W and conveyed. As a result, when the sheets are stacked on the stacking tray 203, the discharge positions are alternately shifted every predetermined number of sheets, and the recording sheets P are sorted.

  As shown in FIGS. 1 and 2, a discharge guide plate 205 and a discharge roller pair 206 are disposed downstream of the shift conveyance roller pair 204 in the sheet conveyance direction Y. The discharge roller pair 206 includes a discharge roller 224 and a driven roller 223 provided so as to be able to come into contact with and separate from the discharge roller 224. The recording sheet P is sandwiched between these rollers and discharged to the stacking tray 203. It is to be transported.

  As shown in FIGS. 4 and 5, the discharge roller 224 is supported as two rollers on a shaft 226 extending in the shift direction W, and the shaft 226 is rotationally driven by an exit motor 217, thereby recording sheet P Is rotated in the direction of conveying in the sheet conveying direction Y.

  A moving unit 500 shown in FIG. 5 is disposed in the vicinity of the discharge roller pair 206. The moving means 500 includes a discharge shift motor 501, a gear portion 502 that is rotated by the shift motor 501, and a link portion 503 that moves the shaft 226 in the shift direction W by the rotation of the gear portion 502. The discharge shift motor 501 is connected to the shaft 226 via the gear portion 502 and the link portion 503, and moves the shaft 226 in the shift direction W when the discharge shift motor 501 rotates by a certain amount. The discharge roller 224 is configured to be movable, for example, 10 mm on one side and 20 mm on both sides from the center position in the shift direction W indicated by a two-dot chain line in FIGS.

  That is, the discharge roller 224 is supported by the support shaft 226 that can be moved in the sheet width direction W by the discharge shift motor 501, and the support shaft 226 is reciprocated in the sheet width direction W to displace the position. It is possible.

  The driven roller 223 is rotatably supported by a support shaft 225 as shown in FIGS. The support shaft 225 is attached to the discharge guide plate 205 as shown in FIG. The discharge guide plate 205 is swingably supported by the frame of the sheet post-processing apparatus 200 with one end as a fulcrum, and supports the support shaft 225 on the free end side. The discharge guide plate 205 is separated from the position where the driven roller 223 indicated by a two-dot chain line in FIG. 2 is in pressure contact with the discharge roller 224 and from the discharge roller 224 indicated by a solid line in FIG. Operated to occupy position.

  As shown in FIGS. 4, 6, and 7, the driven roller 223 includes four rollers 223 a, 223 b, 223 c, and 223 d in the present embodiment, and matches the movement amount of the discharge roller 224 by the discharge shift motor 500. Has been placed.

  The discharge roller pair 206 is in the shift mode or the staple mode, and when the discharge rollers 224 and 224 are moved by the discharge shift motor 501 to the back side W1 of the apparatus, which is one side in the sheet width direction W, the discharge roller 224. 224 and rollers 223a and 223b, and when the discharge rollers 224 and 224 are moved to the front side W2 which is the other side in the sheet width direction W, the discharge rollers 224 and 224 and the rollers 223c, The recording sheet P is sandwiched using 223d. In the normal mode, the paper discharge roller pair 206 does not move in the shift direction, and the paper discharge rollers 224 and 224 and the rollers 223b and 223c are used at the initial positions shown by the two-dot chain lines in FIGS. Then, the recording sheet P is sandwiched.

  In this embodiment, the initial position of the paper discharge roller pair 206 is a position where the paper discharge rollers 224 and 224 and the rollers 223b and 223c shown by two-dotted lines in FIGS. The initial position of the paper discharge roller pair 206 is the same position as the initial position of the shift conveying roller pair 204 in the shift direction W, and these initial positions are the recording sheet P when the shift process is not performed on the recording sheet P. And the center position in the shift direction W.

  In the sheet post-processing apparatus 200, the rotation direction and the rotation amount of the discharge shift motor 501 are made the same in accordance with the rotation direction and the rotation amount of the shift motor 401, and the discharge roller 224 is moved in the same direction as the movement direction of the shift conveying roller 204A. By sandwiching the recording sheet P with the driven rollers 223 (223a to 223d) arranged in accordance with the moving direction and position of the discharge roller 224, the central position of the recording sheet P can always be held and discharged. It is said that. That is, the discharge roller 224 is configured to be movable by the moving unit 500 in the same direction as the shift transport roller 204A by the shift unit 400.

  When the shift mode is set in the image forming apparatus and image formation is performed, the recording sheet P reaching the discharge roller pair 206 is moved by a certain amount in the shift direction W by the shift conveyance roller pair 204. The discharge roller 224 is moved in the same shift direction by the amount of movement of the recording sheet P shifted by the shift conveying roller pair 204 by driving the discharge shift motor 501 before the recording sheet P arrives. At this time, since the movement direction of the shift of the recording sheet P by the shift motor 401 changes depending on the number of copies divided for each of a plurality of sheets, the discharge roller 224 is moved only at the beginning of the copy and moved until it reaches the next copy. It is driven by the discharge motor 217 while being held at the position (shift position). That is, when the number of recording sheets P after image formation is divided into a plurality of sheets, the shift motor 401 and the paper discharge shift motor 501 are operated only once for each section, and the pair of shift transport rollers 204 and the paper are discharged. The roller 224 is held at the position moved in the shift direction W. When shifting to the next portion, the shift discharge motor 501 is driven, and the discharge roller 224 moves in the direction opposite to the first shift movement.

  A sheet pressing member 209 for pressing the recording sheets P stacked on the stacking tray 203 is disposed at the attachment portion of the stacking tray 203 to the sheet post-processing apparatus 200. The sheet pressing member 209 is supported by the frame of the sheet post-processing apparatus 200 so as to be rotatable about its base end, and the sheet pressing releasing operation and the sheet pressing operation are performed by turning on / off a solenoid 218 serving as a driving unit. Is called. That is, when the solenoid 218 is turned on in accordance with the conveyance of the recording sheet P, the pressing operation of the sheet pressing member 209 is released, and when the recording sheet P passes the discharge roller pair 206, the solenoid 218 is turned off to press the recording sheet P. Do.

  The stacking tray 203 includes a fixed tray portion 208a on the downstream side in the transport direction and a movable tray portion 208b on the upstream side. The movable tray portion 208b can be moved up and down by a tray DC motor 221a and a cam / link mechanism 221b. The movable tray portion 208b is pivotally supported by the fixed tray portion 208a via the support shaft 221c with the upstream end as a pivot end, and the operating end of the cam / link mechanism 221b is supported by the movable tray 208b. It is connected. As a result, the tray DC motor 221a rotates, and the movable tray portion 208b swings around the support shaft 221c according to this rotation.

  When the number of discharged recording sheets P reaches a certain number, the movable tray 208b rotates the tray DC motor 221a according to a command from the control unit described later, and lowers the free end of the movable tray unit 208. In addition, a tray paper surface sensor (not shown) is arranged on the sheet pressing member 209. If the tray paper surface sensor is off while the sheet pressing member 209209 is pressing the recording sheet P, the stacking tray 203 is moved to the paper surface sensor. The stacking tray 203 is lowered until the paper surface sensor is turned off, and is raised until the paper surface sensor is turned on again, and then the height of the stacking tray 203 on which the recording sheets P are stacked. Is configured to be kept constant.

  In this manner, the free end of the movable tray unit 208b is moved up and down according to the recording sheet stacking state of the stacking tray 203, and the distance from the nip portion of the discharge roller pair 206 to the recording sheet stacking unit on the movable tray unit 208b is made constant. By maintaining the contact angle between the recording sheet P discharged from the discharge roller pair 206 and the movable tray portion 208b, the alignment quality of the recording sheets P stacked on the stacking tray 203 can be stabilized. Can be loaded.

By repeating such an operation, the recording sheets P sorted on the stacking tray 203 are stacked.
(Staple mode)
Between the shift conveying roller pair 204 shown in FIG. 2 and the discharge roller pair 206 provided immediately before discharging to the stacking tray 203, a hitting roller 211 driven in the vertical direction by a stepping motor (not shown) is disposed. . The hitting roller 211 includes a lever portion and a roller portion that move up and down, and the roller portion is configured to be rotationally driven by a discharge motor 217 in a direction opposite to the direction in which the recording sheet P is conveyed toward the stacking tray 203. .

  In this stapling mode, at the timing when the trailing edge of the recording sheet P passes through the shift conveyance roller pair 204, a stepping motor (not shown) is operated to lower the tapping roller 211, and the recording sheet P is used as a stacking means at the roller portion. The roller is pressed against the staple tray 219 and further rotated by the discharge motor 217 to switch back until the trailing edge of the recording sheet P hits the trailing edge reference fence 220. A return roller 214 driven by an inlet motor 216 is disposed above the rear end reference fence 220, assisting the switchback of the recording sheet P, and aligning the sheet conveyance direction. This alignment is performed with reference to the rear end reference fence 220 when the end of the recording sheet P abuts against the rear end reference fence 220.

  When the switchback of the recording sheet P is completed, the sheet post-processing device 200 aligns the recording sheet P in the sheet width direction that is perpendicular to the sheet conveyance direction by the jogger fence 212 disposed on the staple tray 219. . The jogger fence 212 includes a fixed part and a movable part. The movable part moves in the sheet width direction and moves so that the end of the recording sheet P is sandwiched between the fixed part and contacts the end of the recording sheet P for recording. The sheet P is aligned with the reference position and aligned.

  At that time, the end surface on one side of the rear end of the recording sheet P is inserted up to the staple needle driving position of the stapler 215 serving as a stapling processing means, and a conveying operation, a switchback operation, and an alignment operation of a predetermined number of recording sheets P are performed. After the completion, the staple processing is performed and the bundle is bound into a predetermined number of sheets. For this reason, in this embodiment, the rear end reference fence 220 and the jogger fence 212 function as an alignment unit.

  After the stapling process, the sheet post-processing device 200 lowers the discharge guide plate 205 and sandwiches the recording sheet bundle by a discharge roller pair 206 including a discharge roller 224 and a driven roller 223 attached to the discharge guide plate 205. Then, by driving the discharge motor 217, the recording sheet bundle is discharged to the stacking tray 203. At this time, the discharge roller 224 occupies an initial position (center position) in the shift direction, and sandwiches the recording sheet by the discharge driven rollers 223b and 223c. After the discharge of the recording sheet bundle is started, the discharge motor 217 is driven for a predetermined number of steps, and then the solenoid 218 is turned on to release the sheet pressing member 209 and further the stacking tray 203 is lowered by a certain amount. Next, at the timing when the trailing end of the recording sheet bundle passes through the bundle discharge sensor 210 disposed in front of the discharge roller pair 206, the discharge guide plate 205 is raised, the discharge motor 217 is stopped, and the next recording sheet P is stopped. Prepare for acceptance. Further, the solenoid 218 is turned off at the timing when the rear end of the recording sheet bundle passes the bundle discharge sensor 210 and the sheet bundle is pressed by the recording sheet pressing member 209. Reference numeral 213 denotes a paper presence / absence sensor that detects the presence / absence of a recording sheet on the staple tray 219, and is used for detecting remaining paper in the apparatus when the power is turned on or a jam occurs.

  As described above, in this embodiment, since the discharge roller 224 is moved in the same direction by the moving unit 500 by the shift movement amount of the recording sheet P by the shift unit 400, the recording sheet P can always be held at the center position. it can. For this reason, the manner in which the conveying force is applied to the shifted recording sheet P is stabilized, and the alignment accuracy during sheet stacking can be improved.

  When printing a plurality of copies with a plurality of recording sheets P as one copy, the shift conveyance roller pair 204 and the discharge roller 224 are held at the corresponding shift position of the copy until printing of one copy is completed. Compared with the case where the shift conveyance roller pair 204 and the paper discharge roller 224 are moved in the shift direction in correspondence with each recording sheet P during the printing of the copy part, the shift conveyance roller pair 204 and the paper discharge roller 224 are moved more frequently. Less. For this reason, the shift operation delay when the recording sheet P is discharged is reduced, it is possible to cope with high-speed printing, and productivity can be improved.

  Since a plurality of driven rollers 223 constituting the discharge roller pair 206 are arranged on the discharge guide plate 205, the apparatus configuration can be simplified.

DESCRIPTION OF SYMBOLS 100 Image formation part 200 Sheet post-processing apparatus 201,204 Conveyance means 203 Sheet stacking part 206 Discharge roller pair 223 (ad) Other roller 224 One roller 300 Image reading part 400 Shift means 500 Moving hand.

P Recording sheet Y Sheet conveyance direction W Shift means

JP 2006-137530 A

Claims (4)

A shift unit that moves the recording sheet after image formation conveyed by the conveyance unit in a shift direction orthogonal to the sheet conveyance direction; In a sheet post-processing apparatus having a discharge roller pair for discharging the moved recording sheet to the sheet stacking unit,
A sheet post-processing apparatus having a moving means for moving one roller of the discharge roller pair in the same direction as a shift direction by the shift means. The sheet post-processing apparatus according to claim 1,
In the case where the plurality of recording sheets after the image formation is divided into a plurality of sheets, the moving means operates only once for one section and holds the one roller in a position moved in the shift direction. A sheet post-processing apparatus. The sheet post-processing apparatus according to claim 1 or 2,
2. The sheet post-processing apparatus according to claim 1, wherein a plurality of the other rollers of the discharge roller pair are arranged at positions facing one of the moved rollers when the one roller moves in the shift direction. An image reading unit and an image forming unit;
4. An image forming apparatus comprising: the sheet post-processing apparatus according to claim 1 disposed between the image reading unit and the image forming unit.

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