JP2011178510A - Sheet aligning device, sheet post-processing device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet aligning device capable of completely eliminating a possibility of the contamination of image caused by the contact of sheets immediately below return rollers when the sheets are aligned vertically, and to provide a sheet post-processing device and an image forming device. <P>SOLUTION: The return rollers 211 are pressed against the surface of a sheet P2 discharged to a staple tray 219 beyond a rear end reference fence 220 which is positioned between an already aligned sheet P1 and a retreated side movable fence 212a and then rotated to feed back the sheet P2 until the rear end of the sheet is brought into contact with the rear end reference fence 220. The already aligned sheet P1 is absent immediately below the return rollers 211. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a sheet aligning device that aligns sheets discharged to a tray, a sheet post-processing device including the sheet aligning device, an image forming apparatus, and an image forming system.

  The sheet post-processing device provided in the electrophotographic image forming apparatus is a sheet that has been discharged one by one in order to shift sort or staple the sheets discharged from the image forming apparatus main body. It is equipped with a mechanism that stacks and aligns the trays.

  In particular, in the case of stapling, after a sheet received from the image forming apparatus main body is placed on a temporary stacking tray called a stapling tray, it is necessary to transport and stack the sheets to a position where the stapler can perform stapling processing.

  As a technique for this purpose, a mechanism is known in which a reference fence is provided as a reference for aligning stacked sheets, and the sheets placed on the staple tray are abutted and aligned one by one on the reference fence. In this case, the alignment direction includes the vertical direction of the sheet (sheet discharge direction) and the horizontal direction. For the vertical alignment of the sheet, a rear end reference fence and a return roller are used. It is known to use a reference fence and a side movement fence.

  In particular, the former sheet is aligned in the vertical direction by pressing the return roller onto the received sheet and rotating the return roller as a method of abutting the received sheet against the rear reference fence. A conveying force consisting of the applied pressure and the friction coefficient of the roller material was generated, and the sheet was conveyed and abutted against the rear end reference fence.

However, when the already aligned sheet is already on the staple tray, the next received sheet is placed on the upper surface of the already aligned sheet, and in that state, the returning operation by the return roller and the feeding back operation are performed. Will be.
Therefore, there is a risk that the sheets may be rubbed directly under the return roller, and the toner fixed on the sheet may appear on the upper surface of the sheet immediately below and become dirty. This problem is not a problem peculiar to stapling, but is a problem common when sheets immediately after image formation are aligned on a tray.

  As a prior art for preventing sheet smearing at the time of sheet alignment, for example, paper stacking that prevents the image smearing caused by always contacting the same position by making it possible to change the position of pressing the sheet received by the return roller An apparatus is known (see, for example, Patent Document 1).

However, the above-described sheet stacking apparatus is still capable of performing the returning operation by the return roller with respect to the uppermost sheet on which the sheets are overlapped, and has not completely wiped out the possibility of the image contamination described above. .
Accordingly, the present invention provides a sheet aligning device, a sheet post-processing device, and an image forming apparatus that completely eliminate the possibility of image smearing when the sheets are aligned in the vertical direction just below the return roller. The task is to do.

In order to solve the above problems, the sheet aligning apparatus, the sheet post-processing apparatus, and the image forming apparatus according to the present invention employ the following technical means.
The invention according to claim 1 is characterized in that a tray on which discharged sheets are stacked and a sheet rear end opposite to a sheet front end which is a discharge direction side of the sheet are abutted against each other, and the sheet in the tray The rear end reference fence to be the position of the vertical alignment reference, and one end of both ends of the sheet discharged to the tray in the direction orthogonal to the plan view are abutted, and the side of the sheet in the tray A side reference fence to be a reference position of direction alignment, and the other end of the sheet discharged to the tray so that the sheet is pushed and moved until one end of the sheet hits the side reference fence. It is possible to move forward by hitting, and it is possible to move backward so that the end of one side of the sheet hits the side reference fence and separates from the aligned sheet Of the surface of the sheet discharged to the tray beyond the rear end reference fence, the surface located between the already aligned sheet and the retracted side moving fence. The return roller that rotates by pressing and feeds back the sheet until the rear end of the sheet hits the rear end reference fence, and the return so that the horizontal alignment is performed next to the vertical alignment of the sheets. The sheet aligning apparatus includes an operation control unit that controls the operation of the roller and the side moving fence.
According to a second aspect of the present invention, in the first aspect, before the movement control unit starts the return movement by the return roller, the side movement fence is moved to a position where it comes into contact with the other end of the seat, or It is characterized by advancing to the vicinity.
According to a third aspect of the present invention, in the first or second aspect, the side moving fence is formed in a plate shape that is longer on the downstream side in the sheet discharging direction than the arrangement of the return rollers.
According to a fourth aspect of the present invention, in the method according to any one of the first to third aspects, the return roller generates a force directed toward the side moving fence at the rear end of the sheet when the sheet is fed back. It is provided as follows.
According to a fifth aspect of the present invention, the tray is a staple tray, and a stapler that causes the sheet bundle aligned with the staple tray by the sheet aligning device according to any one of claims 1 to 4 to perform a staple process. A sheet post-processing apparatus provided with
According to a sixth aspect of the present invention, there is provided an image forming apparatus including the sheet aligning device according to any one of the first to fourth aspects.
According to a seventh aspect of the invention, there is provided an image forming apparatus including the sheet post-processing apparatus according to the fifth aspect.

  According to the present invention, the return roller is pressed against the surface located between the already aligned sheet and the retracted side moving fence among the surfaces of the sheet discharged to the tray beyond the rear end reference fence. Since the sheet is fed back until the trailing edge of the sheet hits the trailing edge reference fence, there is no sheet that is already aligned under the return roller. There is no scumming, and the possibility of image smearing when sheets are aligned in the vertical direction can be completely eliminated.

1 is a schematic longitudinal sectional view illustrating a configuration of an image forming apparatus including a sheet aligning device according to the present embodiment. It is a typical longitudinal cross-sectional view which shows the structure of the sheet post-processing apparatus to which the sheet aligning apparatus is applied. 2 is a block diagram illustrating an electrical configuration of a sheet post-processing apparatus and an image forming apparatus main body. FIG. FIG. 4 is a schematic vertical sectional view around the sheet post-processing apparatus showing a sheet delivery operation from the image forming apparatus main body to the sheet post-processing apparatus. FIG. 5 is a schematic longitudinal sectional view illustrating a sheet delivery operation subsequent to FIG. 4. FIG. 10 is a schematic plan view illustrating a sheet aligning operation by the sheet aligning apparatus. FIG. 7 is a schematic plan view illustrating a sheet aligning operation following FIG. 6. FIG. 8 is a schematic plan view illustrating a sheet alignment operation following FIG. 7. FIG. 9 is a schematic plan view illustrating a sheet aligning operation following FIG. 8.

Next, an embodiment of an image forming apparatus provided with a sheet aligning device according to the present invention will be described.
As shown in FIG. 1, the image forming apparatus according to the present exemplary embodiment includes an image forming apparatus main body 100 including an image reading apparatus 300 and a sheet post-processing apparatus 200 including a sheet aligning apparatus. .

  The image forming apparatus main body 100 is an indirect transfer type tandem color image forming apparatus. In FIG. 1, a process unit 110 disposed substantially adjacent to the central portion and a lower portion of the process unit 110 are provided. The optical writing unit 111, the paper feeding unit 120 provided below the optical writing unit 111, the fixing unit 150 provided above the process unit 110, and the sheet picked up by the paper feeding unit 120 are secondary An image is formed on one side of a sheet feeding conveyance path (vertical conveyance path) 130 that conveys the image to the transfer unit 140 and the fixing unit 150, a discharge path 160 that conveys the sheet on which the toner image is fixed to the sheet post-processing apparatus 200 side, and A double-sided conveyance path 170 for reversing the sheet to form an image on the other side, and extending in the lateral direction above the process unit 110 and in reverse The intermediate transfer belt 112 bridged rotatably around, and a primary transfer roller provided to face the process unit 110 to the inside of the intermediate transfer belt 112.

  Each process unit 110 is arranged along the outer periphery of the photosensitive drum on which a latent image and a toner image are formed, and a charging unit that uniformly charges the photosensitive drum, and the optical writing unit 111 is used as a photosensitive drum. A developing unit that develops the formed latent image into a toner image, a cleaning unit that cleans transfer residual toner paper dust on the photosensitive drum, and a static elimination unit that removes the photosensitive drum and prepares for the next image formation. The four process units 110 include a yellow toner image for forming a yellow toner image, a magenta toner image for forming a magenta toner image, a cyan toner image for forming a cyan toner image, and a black toner image for forming a black toner image. Consists of.

  The intermediate transfer belt 112 is rotatably supported by a plurality of support rollers, and one of the support rollers 114 is opposed to the secondary transfer roller 115 via the intermediate transfer belt 112 by the secondary transfer unit 140. In addition, the image on the intermediate transfer belt 112 can be secondarily transferred to the sheet.

The paper feeding unit 120 includes a paper feeding tray 121, a pickup roller 122, and a paper feeding / conveying roller 123, and sends out a sheet picked up from the paper feeding tray 121 along the vertical conveying path 130. . An image is transferred to the fed sheet by the secondary transfer unit 140 and is sent to the fixing unit 150.
The fixing unit 150 includes a heating roller and a pressure roller pressed against the heating roller so as to be able to rotate. Heating and pressing are performed in a process in which the sheet passes through a nip as a pressing portion between the two. The toner image is fused and solidified on the sheet.

  A discharge conveyance path 160 and a double-sided conveyance path 170 are provided downstream of the fixing unit 150, both of which are branched in two directions by a branching claw 161 and conveyed to the sheet post-processing apparatus 200 side, and a double-sided conveyance path. The transport path is selected when transported to 170. A branch conveyance roller 162 is provided in the immediate vicinity of the branch claw 161 on the upstream side in the sheet conveyance direction, and applies a conveyance force to the sheet.

As shown in FIGS. 1 and 2, the sheet post-processing apparatus 200 is disposed inside the image forming apparatus main body 100, performs a predetermined process on the image-formed sheet conveyed from the image forming apparatus main body 100, and is most downstream. And is described later in detail.
The image reading apparatus 300 scans an original set on a contact glass, reads an image on the original surface, and generates print data.

Next, the operation control unit 410 of the image forming apparatus main body 100 and the operation control unit 400 of the sheet post-processing apparatus 200 will be described with reference to FIG.
The operation control unit 410 of the image forming apparatus main body 100 includes a CPU 411, a ROM 412, a RAM 413, a nonvolatile RAM 414, a serial I / F 415, and a timer 416.

  The program code for operation control related to image formation is stored in the ROM 412, and the CPU 411 expands the program code in the RAM 413, stores data necessary for control in the RAM 413, and uses the RAM as a work area according to the program code. The defined image formation control is executed.

  The operation control unit 410 of the image forming apparatus main body 100 includes a motor used in the process unit 110, various DC loads 450 such as various motors and clutches in the sheet feeding unit 120, the sheet feeding conveyance path 130, and the double-side conveyance path 170, and various types. The AC load 470, various sensors 460 such as a temperature sensor for detecting the temperature of the heating roller, the image reading device 300, and the operation display 440 are electrically connected, and each of these parts is triggered by the input of the operation display 440 as one trigger. To be controlled.

The operation control unit 400 of the sheet post-processing apparatus 200 includes a CPU 401, a ROM 402, a RAM 403, a serial I / F 404, and a timer 405.
A program code for a series of operation control including operation control related to sheet alignment, which is a main part of the present invention, is stored in the ROM 402, the CPU 401 expands the program code in the RAM 403, and stores data necessary for control in the RAM 403. The sheet post-processing device defined by the program code is executed while using the RAM as a work area, and various DC loads 420 are controlled.

  The image forming apparatus main body 100 and the sheet post-processing apparatus 200 exchange commands necessary for sheet conveyance control via the serial I / Fs 415 and 404, and the sheet post-processing apparatus 200 receives the commands and sheets obtained from the various sensors 430. Based on the position information, sheet conveyance control and sheet post-processing control are performed.

Next, an outline of a series of operations of the image forming apparatus main body 100 will be described with reference to FIG.
First, image data to be used for writing is generated based on document data read from the image reading device 300 or print data transferred from an external PC or the like, and each photosensitive drum is generated from the optical writing unit based on the image data. The toner image formed for each color is transferred so as to sequentially overlap the intermediate transfer belt 112.

  On the other hand, a sheet is sent out from the paper feed tray 121 according to image formation. The sheet is temporarily stopped by a registration roller (not shown) immediately before the intermediate transfer unit 140 and is sent out in synchronization with the leading edge of the image on the intermediate transfer belt 112. The toner image on the intermediate transfer belt 112 is secondarily transferred by the intermediate transfer unit 140 to the fed sheet, and is sent to the fixing unit 150. The fixing unit 150 fixes the toner image on the sheet.

In the case of single-sided printing and after double-sided printing of double-sided printing, the sheet is conveyed to the discharge path 160 side by switching operation of the branch claw 161, and in the case of double-sided printing, the sheet is conveyed to the double-sided conveyance path 170 side. When the sheet is conveyed to the double-sided conveyance path 170, the sheet is reversed, sent to the last intermediate transfer unit 140, an image is formed on the other side, and then returned to the discharge path 160 side.
The sheet conveyed to the discharge path 160 side is conveyed to a sheet post-processing apparatus 200 described later, and is subjected to predetermined sheet processing by the sheet post-processing apparatus 200 or discharged to the discharge tray 203 without processing.

Next, a sheet post-processing apparatus provided with a sheet aligning apparatus, which is a main part of the present invention, will be described in detail with reference to FIG.
The sheet post-processing apparatus 200 according to the present embodiment includes an inlet roller pair 201, a discharge conveyance path 202, a shift discharge roller pair 204, a staple tray 219, a return roller 211, a second return roller 214, a rear An end reference fence 220, a side moving fence 212a, a side reference fence 212b, a stapler 215, a discharge roller 206, a discharge tray 203, and an operation control unit 400 are provided.

  That is, the sheet receiving unit of the sheet post-processing apparatus 200 includes an inlet roller pair 201 that receives a sheet from the discharge conveyance path 160 of the image forming apparatus 100, and a discharge conveyance path 202 that conveys the received sheet to the shift discharge roller pair 204 side. A shift discharge roller pair 204 having a function of shifting and discharging the sheet is provided on the discharge tray 203. The shift conveyance roller pair 204 is provided at the most downstream end of the discharge conveyance path 202, and in a direction orthogonal to the sheet conveyance direction (depth direction in FIG. 2) with respect to the sheet conveyance direction by a shift motor (not shown). It is movable and rotatable.

  Among these, the discharge conveyance path 202 is configured to include a conveyance belt spanned on a pulley or the like provided on the rotation shaft of the inlet motor 216 that is the inlet roller pair 201 or the stepping motor, and the rotation shaft of the inlet motor 216 is the rotation shaft. By rotating, the conveyance belt is driven to rotate, and the sheet is conveyed along the discharge conveyance path 202.

  An inlet sensor 207 that detects the leading edge and the trailing edge of the sheet is disposed on the inlet side of the discharge conveyance path 202. The timing at which the sheet post-processing is performed is determined by the detection signals of the leading and trailing edges of the sheet detected by the entrance sensor 207.

Here, the operation control for transferring a sheet from the image forming apparatus main body 100 to the sheet post-processing apparatus 200 will be described with reference to FIGS.
4 shows a state when the leading edge of the sheet is at the position of the branch conveyance roller 162 of the image forming apparatus main body 100, and FIG. 5 shows a state when the trailing edge of the sheet is at a position passing through the branch conveyance roller 162.

In FIG. 4, when the image forming process by the image forming apparatus main body 100 starts, an activation signal is transmitted from the image forming apparatus main body 100 to the sheet post-processing apparatus 200. By this activation signal, the sheet post-processing apparatus 200 is ready to receive.
After the image forming process as described above, when the image is transferred to the sheet by the secondary transfer unit 140 and the leading edge of the sheet reaches the branch conveyance roller 106, the sheet is discharged from the image forming apparatus main body 100 to the sheet post-processing apparatus 200. A start signal (hereinafter referred to as a discharge ON signal) is transmitted.

In response to the discharge ON signal, driving of the inlet motor 216 of the sheet post-processing apparatus 200 is started, and the inlet roller pair 201 and the shift discharge roller pair 204 are rotationally driven.
The rotational speed of the inlet roller pair 201 and the shift discharge roller pair 204 at this time, that is, the sheet conveying speed (linear speed, hereinafter the same) is the same as the conveying speed of the sheet conveyed by the image forming apparatus main body 100 ( This speed is referred to as the first speed).
When the sheet is further conveyed and the trailing edge of the sheet passes the branch conveying roller 162, a sheet discharge completion signal (hereinafter referred to as a discharge OFF signal) is transmitted from the image forming apparatus main body 100 to the sheet post-processing apparatus 200. This state is the state of FIG.

  At this time, if the sheet has reached the inlet sensor 203 disposed in the discharge conveyance path 202 of the sheet post-processing apparatus 200, the sheet is accelerated to the second speed. The acceleration is performed for each roller pair after the entrance roller pair 201. If the sheet does not reach the inlet sensor 203, it is uncertain whether or not the sheet is nipped by the nip of the inlet roller pair 201, so there is no meaning of acceleration. Therefore, the sheet is further conveyed to the inlet sensor 203 at the first speed, and when reached, the sheet is accelerated to the second speed.

  The position of the sheet is managed by the number of drive steps of the inlet motor 216 and the discharge motor 217 from the time when the sheet reaches the inlet sensor 203, and the CPU 401 knows where the sheet is currently being conveyed. Thereafter, various processes such as sheet sorting, alignment, and binding are executed according to the selected mode, that is, the shift mode sheet or the staple mode.

  As described above, the sheet post-processing apparatus 200 according to the present embodiment includes a shift mode that shifts and discharges sheets, a staple mode that binds and discharges a plurality of sheets, and a straight that does not perform sheet sorting or binding processing. Since there are modes and they are different, a series of operations will be described with reference to FIG. 2 and FIGS. The staple mode will be described in the shift mode.

(1) Shift mode The shift mode is a mode in which the sheet discharge position is shifted in a direction orthogonal to the plane of the sheet with respect to the sheet conveyance direction for each predetermined number of sheets when the sheets are discharged, and the sheets are sorted by this shift.

  First, when the shift conveying roller pair 204 sorts the sheets in the shift mode, the sheet conveying direction is moved in a direction orthogonal to the sheet conveying direction with respect to the sheet conveying direction every predetermined number of sheets, and the sheet conveying direction is changed to a direction orthogonal to the sheet planar view. Is shifted by the amount moved to the discharge tray 203. Accordingly, the stacking position of the discharge tray 203 is shifted every predetermined number of sheets, and the sheets can be sorted. In the straight mode, the shift conveyance roller pair 204 is stopped from moving in the direction perpendicular to the plan view of the sheet with respect to the sheet conveyance direction.

  A discharge guide plate 205 that can be moved up and down by a stepping motor (not shown) and a discharge roller 206 that is rotationally driven by a discharge motor 217 are disposed downstream of the shift conveyance roller pair 204. The sheet is sandwiched between the discharge roller 206 and a driven roller attached to the discharge guide plate 205 and discharged to the discharge tray 203.

A sheet presser 209 for pressing the sheets stacked on the discharge tray 203 is disposed at the attachment portion of the discharge tray 203 to the main body of the sheet post-processing apparatus 200. The sheet press release operation is performed by turning on / off the solenoid 218. Sheet pressing operation is performed.
That is, the solenoid 218 is turned ON in accordance with the conveyance of the sheet to release the pressing operation of the sheet presser 209, and when the sheet passes the discharge roller 206, the solenoid 218 is turned OFF to perform the sheet presser.

The discharge 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, and the movable tray portion 208b moves 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 sheets 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 208.

  In addition, a tray paper surface sensor (not shown) is disposed on the sheet presser 209. If the tray paper surface sensor is OFF while the sheet presser 209 is holding the sheet, the discharge tray 203 is raised until the paper surface sensor is turned ON. If the paper surface sensor is ON, the discharge tray 203 is lowered until the paper surface sensor is turned OFF, and then raised until it is turned ON again, so that the height of the discharge tray on which sheets are stacked is kept constant.

Thus, by moving the free end of the movable tray unit 208 up and down according to the sheet stacking state of the discharge tray 203 and keeping the distance from the nip portion of the discharge roller 206 to the sheet stacking unit of the movable tray unit 208 constant, The contact angle between the sheet discharged from the discharge roller 206 and the movable tray unit 208 is made constant, the alignment quality of the sheets stacked on the discharge tray 203 can be stabilized, and a large number of sheets can be stacked.
By repeating the above operation, the sorted sheets are stacked on the discharge tray 203.

(2) Staple mode The staple mode is a mode in which the stapler 215 binds and discharges sheets every predetermined number of sheets.
That is, in this stapling mode, the sheet is once discharged onto the staple tray 219, and the sheet is returned by the return roller 211 and the second return roller 214 until it hits the rear end reference fence 220, in the longitudinal direction of the sheet (sheet In the discharge direction), the rear end reference fence 220 and the side moving fence 212a align the sheets in the lateral direction (sheet plan view, orthogonal direction) each time the sheets are discharged, and a predetermined number of sheets are discharged. This is a mode in which the stapler 215 performs the binding process after each alignment and then discharges the sheet to the discharge tray 203, and is configured using the sheet aligning device according to the present invention.

  This sheet aligning device includes a staple tray 219, a rear end reference fence 220, a side reference fence 212b, a side moving fence 212a, a return roller 211, a second return roller 214, and the shift discharge roller pair 204 described above. The operation control unit 400 is provided.

  The staple tray 219 is positioned such that the downstream end of the transport is positioned in the vicinity of the discharge roller 206, the upstream end of the staple tray 219 is positioned between the inlet roller pair 201 and the second return roller 214, and The sheet discharged from the pair of shift conveying rollers 204 is provided so as to extend substantially horizontally in the center of the apparatus so that the end on the upstream side is lower than the end on the downstream side of the conveyance. It is supposed to be loaded. The width of the staple tray 219 is larger than the required width of the sheet.

  The trailing edge reference fence 220 is a plate-like member provided so as to rise from the end of the staple tray 219 on the upstream side of conveyance, and the trailing edge of the sheet opposite to the leading edge of the sheet, which is the sheet discharge direction side. The sheet is abutted to be a reference position in the vertical direction of the sheets in the staple tray 219.

  As shown in FIG. 6, the side reference fence 212b is a plate-like shape provided so as to rise from one end (the left end in FIG. 6) of both ends in the width direction of the staple tray 219. One of the ends of the sheet discharged to the staple tray 219 in the direction orthogonal to the plan view is abutted to be a reference position for the sheet in the staple tray 219 in the lateral direction.

  The side moving fence 212a is a plate-like member, and is disposed so as to face the side reference fence 212b so as to be longer on the downstream side in the sheet discharging direction than the arrangement of the return rollers 211, and in the width direction of the staple tray 219. One end side of the two end portions is provided as a base point (standby position) so that it can be advanced toward the side reference fence 212b and can be retracted from the side reference fence 212b by a driving means (not shown). . In this way, the side moving fence 212a moves the sheet on the other side of the sheet discharged to the staple tray 219 so that the sheet moves until the end on one side of the sheet discharged to the staple tray 219 hits the side reference fence 212b. It is configured to be able to advance toward the end, and to be retractable so that the end on one side of the sheet abuts against the side reference fence 212b and leaves the aligned sheet.

  The return roller 211 includes a sheet that has already been abutted against the side reference fence 212b out of the surface of the sheet that has been discharged to the staple tray 219 beyond the rear end reference fence 220, and a side moving fence that has retreated to the base point. 212 between the shift conveyance roller pair 204 provided at the most downstream end of the discharge conveyance path 202 and the discharge guide plate 205 provided immediately before discharging to the discharge tray 203. It is provided through the tip of a lever that can be swung in the vertical direction by a stepping motor (not shown). It should be noted that the position where the lever is raised most is the standby position of the return roller 211.

  The return roller 211 is driven to rotate in a direction opposite to the sheet conveying direction by a stepping motor (not shown), and moves toward the sheet discharged to the staple tray 219 to be on the surface of the sheet. The sheet is fed back by pressing and rotating in that state. This return amount is until the rear end of the sheet hits the rear end reference fence 220.

  Further, the return roller 211 is provided so that a force directed toward the side moving fence 212a is generated at the rear end of the sheet when the sheet is fed back. For example, the return roller 211 is formed into a truncated cone shape or a shape having different diameters at both ends, and is attached to the lever, or the direction of the lever itself is changed to generate the force.

  The second return roller 214 is provided above the rear end reference fence 220 so as to be driven by an inlet motor 216, assisting in switch back of the sheet, and aligning the sheet conveyance direction. It has become.

  The operation control unit 400 is configured to execute staple mode operation control in addition to the shift mode and straight mode operation control described above, and a series of operations will be described below. For convenience of explanation, it is assumed that there are already aligned sheets on the staple tray 219.

  First, the sheet P2 sent from the image forming apparatus main body 100 is moved to the shift conveyance roller pair 204 by the inlet roller pair 201 (FIG. 6), and shifted toward the side moving fence 212a by the shift conveyance roller pair 204. The paper is discharged onto the staple tray 219. (FIG. 7).

At the time of discharging, the return roller 211 is lowered at the timing when the trailing edge of the sheet passes the pair of shift conveying rollers 204, and the sheet P2 is pressed against the staple tray 219.
Next, before the return operation (rotation) by the return roller 211 is started, the side moving fence 212a positioned at the standby position is advanced to the position in contact with the end of the sheet P2 or the vicinity thereof and stopped, and at the time of switchback. 8 is used as a guide for regulating the skew (inclination) of the sheet P2 in FIG.

  Further, in FIG. 8, the skew direction is a direction in which the left side (sheet leading end side) of the sheet P <b> 2 is directed upward with the return roller 211 as a boundary. It extends to the downstream side in the transport direction (left side in the figure) from the position.

Next, the return roller 211 is rotated until the rear end of the sheet hits the rear end reference fence 220, and the sheet P2 is fed back (FIG. 8).
At this time, of the surfaces of the sheet P2 discharged to the staple tray 219 beyond the rear end reference fence 220, the roller 211 is returned to the surface positioned between the already aligned sheet P1 and the retracted side moving fence 212a. Is pressed to rotate. Accordingly, since the position of the return roller 211 is a position where the sheet P1 already stacked on the staple tray 219 is not located below, there is no centering between the sheets immediately below the return roller 211, and the sheets are aligned in the vertical direction. The risk of image smudges is completely wiped out.

Further, as described above, the return roller 211 is provided so that a force directed toward the side moving fence 212a is generated at the rear end of the sheet when the sheet is fed back, thereby further improving the guide effect of the skew regulation. .
When the rear end of the sheet comes into contact with the rear end reference fence 220 and the vertical alignment of the sheet is completed, the return roller 211 is moved to the standby position.
Next, in order to align the lateral direction of the sheet P2, the side moving fence 212a is moved downward in the figure by a predetermined amount, the sheet P2 is pushed and moved, the sheet P2 is abutted against the side reference fence 212b, and the sheets are already aligned. The position is aligned with the sheet P1 (FIG. 9).

When the sheet alignment of the sheet P2 is finished in this way, the side moving fence 212a is moved to the standby position. By repeating the above-described sheet aligning operation a desired number of times, a desired number of sheet bundles are aligned on the staple tray 219.
In this alignment position, the rear end side of the sheet is a driving position of the binding needle of the stapler 215, and the stapler 215 staples the sheet bundle. The side moving fence 212a moves to the standby position after the stapling process is completed.

After stapling, as shown by the chain line in FIG. 2, the discharge guide plate 205 is lowered, the sheet bundle is sandwiched between the discharge roller 206 and the driven roller attached to the discharge guide plate 205, and the discharge motor 217 is driven to drive the sheet. The bundle is discharged to the discharge tray 203.
After the discharge of the sheet bundle is started, the discharge motor 217 is driven for a certain step, and then the solenoid 218 is turned on to release the sheet presser 209 and further the discharge tray 203 is lowered by a certain amount.

  Next, at the timing when the trailing end of the sheet bundle passes the bundle discharge sensor 210, the discharge guide plate 205 is raised, and the discharge motor 217 is stopped to prepare for receiving the next sheet. At the same timing, the solenoid 218 is turned off to press the sheet. Reference numeral 213 denotes a paper presence / absence sensor that detects the presence / absence of a sheet on the staple tray 219, and is used to detect remaining paper in the apparatus when the power is turned on or when a jam occurs.

  According to the image forming apparatus according to the present embodiment, among the surfaces of the sheet P2 discharged to the staple tray 219 beyond the rear end reference fence 220, the already aligned sheet P1 and the retracted side moving fence 212a are provided. The return roller 211 is pressed against the surface located between the two and rotated so that the sheet P2 is fed back until the rear end of the sheet hits the rear end reference fence 220. The sheet is already aligned immediately below the return roller 211. The sheet P1 is not present. As a result, the sheets do not rub immediately below the return roller 211, and the possibility of image smearing when the sheets are aligned in the vertical direction can be completely eliminated.

The image forming apparatus according to the present embodiment has been described above. However, the above-described embodiment shows an example of a preferred embodiment of the present invention, and the present invention is not limited thereto. Various modifications can be made without departing from the scope of the invention.
For example, in the present embodiment, the sheet aligning apparatus, which is a main part of the present invention, is applied to the sheet post-processing apparatus, and the image forming apparatus including the sheet post-processing apparatus is illustrated. If it is a site | part which piles up sheets, the sheet aligning apparatus which is the principal part of this invention is applicable.

DESCRIPTION OF SYMBOLS 100 ... Image forming apparatus main body 200 ... Sheet post-processing apparatus 219 ... Staple tray 220 ... Rear end reference fence 212a ... Side moving fence 212b ... Side reference fence 211 ... Return roller 215 ... Stapler 400 ... Operation control unit

JP 2007-076903 A

Claims (7)

A tray on which discharged sheets are stacked;
A trailing edge reference fence that is abutted with the trailing edge of the sheet on the opposite side to the leading edge of the sheet, which is the discharging direction of the sheet, and is set as a vertical alignment reference position of the sheet in the tray;
A side reference fence that is abutted on one end of both ends of the sheet discharged in the tray in a direction orthogonal to the plan view, and is set as a horizontal alignment reference position of the sheet in the tray,
The sheet can be moved forward against the other end of the sheet discharged to the tray so that the sheet is pushed until the one end of the sheet hits the side reference fence, and one side of the sheet A side moving fence configured to be retractable so that the end of the side abuts the side reference fence and leaves the sheet aligned sheet;
Out of the surface of the sheet discharged to the tray beyond the rear end reference fence, the sheet is rotated against the surface positioned between the already aligned sheet and the retracted side moving fence. A return roller that feeds back the sheet until the rear end hits the rear end reference fence;
A sheet aligning apparatus comprising: an operation control unit configured to control operations of the return roller and the side moving fence so that horizontal alignment is performed next to vertical alignment of the sheets. .   2. The motion control unit advances the side moving fence to a position in contact with an end on the other side of the seat or to the vicinity thereof before starting a return operation by the return roller. The sheet aligning apparatus according to 1.   3. The sheet aligning apparatus according to claim 1, wherein the side moving fence is formed in a plate shape that is longer on the downstream side in the sheet discharging direction than the arrangement of the return rollers.   The return roller is provided so that a force directed toward the side moving fence is generated at a rear end of the sheet when the sheet is fed back. The sheet aligning apparatus according to item.   The said tray is a staple tray, The stapler is provided with the stapler which makes a sheet bundle aligned with the staple tray by the sheet aligning apparatus of any one of Claims 1 thru | or 4 staple. Sheet post-processing device.   An image forming apparatus comprising the sheet aligning device according to claim 1.   An image forming apparatus comprising the sheet post-processing apparatus according to claim 5.

Images