JPWO2016157590A1 - Sheet post-processing apparatus and image forming system including the same - Google Patents

Abstract

The sheet post-processing device (20) includes a punch hole forming device (21), a processing tray (30), and a discharge tray (50). The processing tray (30) moves the sheet in a direction orthogonal to the discharge direction with the leading end of the sheet protruding on the discharge tray (50), so that the reference discharge position (P1) on the discharge tray (50). Then, it is possible to execute shift discharge for discharging the sheet to the shift discharge position (P2) shifted by a predetermined amount from the reference discharge position (P1) in the direction orthogonal to the discharge direction. When punch holes are formed in the sheet to be shifted, the reference discharge position (P1) and the shift discharge position shifted from the reference discharge position (P1) in the direction opposite to the sheet side edge where the punch holes are formed ( In P2), the sheet is discharged.

Description

  The present invention relates to a sheet post-processing apparatus that performs post-processing such as punch hole forming processing and binding processing on a sheet of paper or the like on which an image is formed by an image forming apparatus such as a copying machine, a facsimile, or a printer, and an image forming system including the same. About.

  2. Description of the Related Art Conventionally, a plurality of sheets (sheets) on which images are formed by an image forming apparatus such as a copying machine or a printer are stacked, and a binding process for binding the stacked sheet bundles together with staples, and punch holes in a punch hole forming apparatus. Paper post-processing devices capable of executing punch hole forming processing for punching (punching) are used.

  In such a sheet post-processing apparatus, the punch hole forming apparatus forms a plurality of punch holes not along the sheet conveying direction but along the edge in the direction orthogonal to the conveying direction. The reason for this is that when punch holes are formed along the edge in the paper transport direction, it is necessary to temporarily stop the paper, and there is a concern about a decrease in productivity (processing efficiency), and the A3 size. This is because there is no demand for forming punch holes along the edges in the paper transport direction because A4 size paper can be transported horizontally (transverse paper) in an image forming apparatus capable of printing on paper.

  However, in recent years, with the demand for space-saving image forming apparatuses, image forming apparatuses that carry A4 size paper vertically (longitudinal paper) are on the market. For this reason, there is a demand for forming punch holes along the edges in the sheet conveyance direction.

  As a method of forming a plurality of punch holes in the paper conveyance direction, for example, in Patent Document 1, when performing folding processing on a punched sheet, the punching of the sheet is overlapped at two places. A post-processing device for changing the drilling position relative to the centerline is disclosed. Further, in Patent Document 2, in a sheet post-processing apparatus that forms punch holes without stopping a sheet being conveyed, a punching device and an end detection unit that detects a side edge of the sheet are orthogonal to the conveying direction. A sheet processing apparatus that can move in the direction and forms punch holes at positions corresponding to the size of the conveyed sheet is disclosed.

JP 2002-68777 A JP 2000-21802 A

  By the way, in a paper post-processing apparatus that performs binding processing and the like while aligning a part of paper on a discharge tray, the subsequent paper moves while rubbing the upper surface of the paper that has already been discharged in the paper width direction. . Therefore, when so-called shift discharge is performed by moving the paper in the direction orthogonal to the discharge direction (paper width direction), the shift amount of the paper (about 10 to 20 mm) and the paper width direction orthogonal to the discharge direction are performed. Since the punch hole formation position (about 10 to 15 mm) from the edge is close, the succeeding paper may be caught in the punch hole of the already discharged paper. As a result, there has been a problem that the paper discharged onto the discharge tray is pushed out and misalignment occurs.

  In view of the above problems, the present invention includes a sheet post-processing apparatus capable of preventing misalignment of a sheet bundle when aligning the sheet bundle by pulling a sheet onto a processing tray using a pair of discharge rollers, and the same. An object is to provide an image forming system.

  In order to achieve the above object, the present invention is a sheet post-processing apparatus including a punch hole forming device, a processing tray, and a discharge tray. The punch hole forming device forms punch holes along the side edge of the sheet parallel to the sheet conveying direction. The processing tray is disposed on the downstream side in the sheet conveying direction of the punch hole forming apparatus, and receives and stacks a predetermined number of sheets. The discharge tray is disposed downstream of the processing tray in the sheet conveying direction, and the sheets stacked on the processing tray are discharged. The processing tray moves the sheet in a direction perpendicular to the discharge direction with the leading edge of the sheet protruding on the discharge tray, and a direction perpendicular to the discharge direction from the reference discharge position on the discharge tray. It is possible to execute shift discharge for discharging a sheet to a shift discharge position shifted by a predetermined amount. When punch holes are formed in the sheet to be shifted and discharged, the sheet is discharged to the reference discharge position and the shift discharge position shifted in the direction opposite to the sheet side edge where the punch hole is formed from the reference discharge position. .

  According to the first configuration of the present invention, when a sheet having punch holes is shifted and discharged, the subsequent sheet moves while contacting the upper surface of the punch hole of the already discharged sheet. The side edge is located downstream in the movement direction. As a result, the side edge of the succeeding sheet can move smoothly without being caught in the punched hole of the already discharged sheet. Therefore, the sheet discharged onto the discharge tray is not pushed out in the shift direction by the subsequent sheet, and it is possible to effectively prevent sheet misalignment and fall from the discharge tray.

Schematic showing the internal configuration of the image forming apparatus 100 and the sheet post-processing apparatus 20 of the present invention. FIG. 2 is a partially enlarged view of the periphery of a processing tray 30 in the paper post-processing apparatus 20 in FIG. 1 and shows a state in which discharge rollers 29a are arranged at a separation position. FIG. 2 is a partially enlarged view around a processing tray 30 in the paper post-processing apparatus 20 in FIG. 1 and shows a state in which a discharge roller 29a is arranged at a contact position. A block diagram showing a control path of an image forming system including the image forming apparatus 100 and the sheet post-processing apparatus 20 The flowchart which shows an example of the punch hole formation process and shift discharge control in the paper post-processing apparatus 20 of this invention. A plan view of a sheet post-processing apparatus 20 that performs shift discharge when a punch hole is not formed on a sheet. A plan view of a sheet post-processing apparatus 20 that performs shift discharge when a punch hole is formed along the front edge of the sheet. A configuration of a comparative example in which the sheet bundle is alternately discharged to the reference discharge position P1 and the shift discharge position P2 shifted to the front side of the apparatus in the side edge direction of the paper P in which the punch hole 90 is formed will be described. Figure According to the present invention, the sheet bundle is alternately discharged to the reference discharge position P1 and the shift discharge position P2 shifted by a predetermined amount to the rear side of the apparatus opposite to the side edge direction of the paper P in which the punch holes 90 are formed. Diagram explaining the configuration A plan view of a sheet post-processing apparatus 20 that performs shift discharge when a punch hole is formed along an edge on the back side of the sheet.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, an image forming system including the image forming apparatus 100 and the sheet post-processing apparatus 20 of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing internal configurations of an image forming apparatus 100 and a sheet post-processing apparatus 20 according to the present invention. In the present exemplary embodiment, a multifunction peripheral is illustrated as an example of the image forming apparatus 100. However, the paper post-processing apparatus 20 of the present invention may be applied to a printer other than a digital multifunction peripheral, such as a laser printer, an inkjet printer, or a facsimile apparatus. Can be similarly connected.

  As shown in FIG. 1, the image forming apparatus 100 is a so-called in-body discharge type digital multi-function peripheral, and roughly includes a main body housing 2a and an upper housing 2b disposed on the main body housing 2a. ing. The upper housing 2b is provided with various mechanisms, which will be described later, for reading an image of an original as an electrical signal, and an original conveying device 3 is attached to the upper portion of the upper housing 2b. On the other hand, the main body housing 2a is provided with various mechanisms, which will be described later, for transferring an image to a sheet based on an electric signal of the read original image. A sheet post-processing device 20 is attached to the left side of the main body housing 2a. ing.

  In the present embodiment, the main body housing 2a includes a lower housing 2aa and a connection housing 2ab that is positioned along the right side and connected to the upper housing 2b. The lower housing 2aa is provided with a paper feeding unit 4 for the paper P, an image forming unit 6 for forming a toner image on the paper P, a fixing device 7 for fixing the toner image on the paper, and the like. The connection housing 2ab is provided with a paper discharge portion (discharge portion) 18 for conveying the fixed paper P and discharging it from the main body housing 20.

  In addition, on the left side of the connecting housing 2ab immediately below the upper housing 2b, an in-body discharge space 16 is formed that is largely open toward the left side and the front. In the in-body discharge space 16, the paper P discharged from the left side surface of the connecting housing 2 ab is received and stacked, and when the paper P is subjected to predetermined post-processing, it is conveyed to the paper post-processing device 20. An enabling relay unit 19 is provided.

  In the main body housing 2 a, the sheet feeding unit 4 disposed at the lower part, the sheet conveying unit 5 disposed on the side and above the sheet feeding unit 4, and the sheet feeding unit 4 are disposed above the sheet feeding unit 4. An image forming unit 6 and a fixing unit 7 disposed on the downstream side of the image forming unit 6 in the sheet conveying direction (the right side in FIG. 2) are provided.

  The paper feed unit 4 is provided with a plurality of paper feed cassettes 4a provided with separation feed means such as paper feed rollers on the downstream side in the paper transport direction. A bundle of sheets P placed in the sheet feeding cassette 4a is fed one by one from the uppermost sheet P to the sheet conveying section 5 by the rotation operation of the sheet feeding roller. The paper transport unit 5 transports the paper P fed from the paper feed unit 4 to the image forming unit 6 by each transport roller pair 5a.

  The image forming unit 6 and the fixing unit 7 are elongated in the width direction (front-rear direction, direction orthogonal to the paper surface of FIG. 1) orthogonal to the paper conveyance direction inside the apparatus main body 100. The image forming unit 6 and the fixing unit 7 are juxtaposed along the conveyance direction (from left to right) of the sheet P in the order of the image forming unit 6 and the fixing unit 7 from the left side in FIG. 1 in the upper part of the lower housing 2aa. Yes.

  The image forming unit 6 forms a predetermined toner image on the paper P by an electrophotographic process. The image forming unit 6 includes a photosensitive drum 9 that is an image carrier that is rotatably supported, and a charging device 11 that is disposed around the photosensitive drum 9 along the rotation direction, an exposure device 12, and the like. A developing device 13, a transfer device 14, a cleaning device 15, and a static elimination device (not shown) are provided. The fixing unit 7 heats and presses the sheet P on which the toner image has been transferred in the image forming unit 6 between a pair of fixing rollers 7a including a heating roller and a pressure roller, thereby forming an unfixed toner image. Fix on the paper P.

  An image reading unit 8 is provided in the upper housing 2b. The image reading unit 8 reads image information of a document. When placing the originals one by one by hand and causing the image reading unit 8 to read the originals, the original conveyance device 3 is opened and the originals are placed on the contact glass 8a provided on the upper surface of the upper housing 2b. When the originals are automatically supplied from the original bundle one by one and are read by the image reading unit 8, the original bundle is placed on the paper feed tray 3 a of the original conveying device 3 in a closed state. When the original bundle is placed on the paper feed tray 3a, the originals from the original bundle are automatically and sequentially sent onto the contact glass 8a one by one. In either case, the original positioned on the contact glass 8a is irradiated with light from an exposure lamp (not shown), and the reflected light is transmitted as image light to an optical system (not shown) such as a reflecting mirror and an imaging lens. To the photoelectric conversion unit (CCD).

  Hereinafter, a basic operation of the image forming apparatus 100 configured as described above will be described. First, the surface of the photosensitive drum 9 that rotates counterclockwise in FIG. 1 is uniformly charged by the charging device 11. Subsequently, based on the image information read by the image reading unit 8, a laser beam from the exposure device 12 (laser device or the like) is applied to the peripheral surface of the photosensitive drum 9, and thereby the surface of the photosensitive drum 9 is statically irradiated. An electrostatic latent image is formed. By supplying toner as a developer from the developing device 13 to the electrostatic latent image, a toner image is formed.

  Next, the paper P from the paper supply unit 4 passes through the paper transport path 5 and is transported toward the photosensitive drum 9 on which the toner image is formed at a predetermined timing. Then, the toner image on the surface of the photosensitive drum 9 is transferred onto the paper P by the transfer device 14 including a transfer roller or the like. The paper P on which the toner image is transferred is separated from the photosensitive drum 9 and conveyed toward the fixing unit 7. The paper P is heated and pressurized when passing through the fixing roller pair 7a to fix the toner image.

  After the transfer of the toner image to the paper P is completed, after the residual toner remaining on the outer peripheral surface is removed by the cleaning device 15, the residual charge is removed by a static eliminator (not shown). A static elimination process is performed. Thereafter, the charging device 11 charges the outer peripheral surface of the photosensitive drum 9 again, and image formation is performed in the same manner.

  The sheet P that has passed through the fixing unit 7 is conveyed in the connection housing 2ab along the sheet conveying path 5 as it is vertically upward. The upper part of the sheet conveyance path 5 branches into two upper and lower conveyance paths toward the left in the connection housing 2ab, and the conveyance direction of the sheet P is switched by a switching claw 17 arranged at the branching portion.

  A paper discharge portion 18 is provided in the connection housing 2ab. The paper discharge unit 18 includes an upper discharge roller pair 18a and a lower discharge roller pair 18b disposed immediately below the upper discharge roller pair 18a, and the paper P conveyed through the paper conveyance path 5 is a switching claw. 17 is guided to an upper conveyance path or a lower conveyance path.

  The paper P guided to the upper conveyance path by the switching claw 17 is discharged leftward from the upper discharge roller pair 18a. The paper P guided to the lower conveyance path by the switching claw 17 is discharged to the left by the lower discharge roller pair 18b. The switching claw 17 is configured to switch the guide direction by the control unit 70 (see FIG. 4).

  The relay unit 19 is detachably attached to the bottom surface 16 a of the in-body discharge space 16. A detection sensor (not shown) for detecting the attachment of the relay unit 19 is provided in the in-body discharge space 16. The detection sensor is configured by a PI sensor or the like, and transmits a detection result to the control unit.

  In addition, an inclined surface that is inclined upward toward the downstream side in the sheet discharge direction (left side in FIG. 1) is formed on the bottom surface 16a. When the relay unit 19 is separated from the in-body discharge space 16, the bottom surface 16a is used as a sheet discharge tray. In this case, the detection sensor detects that the relay unit 19 is not mounted, and when the detection result is transmitted to the control unit, the switching claw 17 guides the paper P to the upper discharge roller pair 18a. The paper P discharged from the upper discharge roller pair 18a is discharged onto the bottom surface 16a.

  On the other hand, when the detection sensor detects that the relay unit 19 is installed in the in-body discharge space 16 and the detection result is transmitted to the control unit 70, the switching claw 17 causes the paper P to be transferred to the lower discharge roller pair 18b. invite. Then, the paper P discharged from the lower discharge roller pair 18 b is carried into the relay unit 19. The paper P carried into the relay unit 19 passes through the relay unit 19 and is carried into the paper post-processing device 20.

  The detection result can be displayed on an operation unit (not shown), and the user can switch the guidance direction of the paper P on the operation panel. Further, the upper surface portion of the relay unit 19 also has a function as a paper discharge tray on which the paper P discharged from the upper discharge roller pair 18a is placed.

  Inside the paper post-processing device 20, a punch hole forming device 21 that forms punch holes on the loaded paper P, a processing tray 30 that stacks a plurality of the loaded paper P, and a processing tray 30. A stapler 40 is provided for binding a bundle of sheets stacked thereon with staples. A discharge tray 50 that can be raised and lowered to a position suitable for discharging the paper P is provided on the side surface of the paper post-processing device 20.

  The punch hole forming device 21 is disposed on the upper portion of the paper post-processing device 20 and forms a plurality of punch holes along one side edge (the front side or the rear side) parallel to the transport direction of the paper P. . At a substantially central portion in the direction (perpendicular to the paper surface in FIG. 1) upstream of the punch hole forming device 21 and perpendicular to the paper transport direction, a pair of paper carry-in rollers in the relay unit 19 is placed in the paper post-processing device 20. A carry-in detection sensor (not shown) for detecting the leading edge of the paper P to be carried in is arranged.

  The control unit 70 controls the driving of the paper carry-in roller pair in the relay unit 19 based on the detection timing of the leading edge of the paper P by the carry-in detection sensor, so that the conveyance direction of the paper P conveyed to the punch hole forming device 21 is controlled. Adjust the punch hole formation position. Specifically, a conveyance direction pulse adjustment value for adding or subtracting a reference conveyance pulse value from the detection of the leading or trailing edge of the paper P by the carry-in detection sensor to the stop of the paper carry-in roller pair is set.

  2 and 3 are partial cross-sectional views around the processing tray 30 in the sheet post-processing apparatus 20. A first discharge roller pair 27 is disposed on the downstream side of the punch hole forming device 21 (see FIG. 1) with respect to the paper transport direction. An actuator type paper detection sensor 28 that detects the passage of the paper P is disposed upstream of the first discharge roller pair 27.

  Further, below the first discharge roller pair 27, a processing tray 30 on which a predetermined number of sheets P conveyed by the first discharge roller pair 27 are aligned and stacked, and a bundle of sheets P stacked on the processing tray 30 ( A stapler 40 (see FIG. 1) that performs a binding process is provided on the sheet bundle.

  A second discharge roller pair 29 that discharges the sheet bundle from the processing tray 30 to the discharge tray 50 is disposed on the downstream side of the processing tray 30 with respect to the sheet conveyance direction. The second discharge roller pair 29 includes a rubber discharge roller 29a that can be rotated forward and backward by a drive motor (not shown), and a resin discharge roller 29b that rotates following the discharge roller 29a. . The discharge roller 29a is supported by a roller holder 31 that can swing up and down about the rotation shaft 31a.

  At the upper side of the processing tray 30 and downstream of the first discharge roller pair 27 (left side in FIG. 2), the paper P carried by the first discharge roller pair 27 is struck in the direction of the processing tray 30 and along the tray surface. A hitting member 33 is provided for the purpose. The processing tray 30 is provided so as to incline downward toward the rear end side (right side in FIG. 2) of the stacked paper P, and the second discharge roller pair 29 rotates in reverse to cause the paper P to move to the rear end. The paper P is drawn onto the processing tray 30 from the side, and the rear end of the paper P comes into contact with the abutting portion 30a. As a result, the sheets are stacked on the processing tray 30 with the rear ends thereof aligned. Further, the processing tray 30 is provided with a pair of side edge alignment cursors 60 for aligning the sheet bundle loaded on the processing tray 30 in the width direction (direction perpendicular to the paper surface of FIG. 2).

  The stapler 40 can be moved in the paper width direction perpendicular to the transport direction by a moving mechanism (not shown), and moves to a predetermined position along the lower end of the processing tray 30 according to the content of the binding process.

  Next, the operation of the sheet post-processing apparatus 20 will be described. When a sheet P (indicated by a broken line in FIGS. 2 and 3) on which image forming processing has been performed by the image forming apparatus 100 is carried in, if punch hole formation is instructed, the sheet P is conveyed by the punch hole forming apparatus 21. Punch holes are formed at predetermined positions (for example, two locations along the side edge on the front side of the apparatus) of the sheet P to be printed. If punch hole formation is not instructed, the paper P passes through the punch hole forming device 21 as it is.

  Then, the paper P is conveyed further downstream by the first discharge roller pair 27. At this time, as shown in FIG. 2, the roller holder 31 swings upward, and the discharge roller 29a is disposed at a position (retracted position) away from the discharge roller 29b. Therefore, the paper P conveyed by the first discharge roller pair 27 protrudes to the discharge tray 50 through the gap between the discharge roller 29a and the discharge roller 29b.

  At the timing when the rear end of the sheet P passes through the first discharge roller pair 27, the roller holder 31 is swung downward and the discharge roller 29a is disposed at a position (contact position) where the discharge roller 29a contacts the discharge roller 29b. Thereafter, the tapping member 33 is driven to cause the paper P to follow the processing tray 30. In this state, by rotating the discharge roller 29a in the reverse direction (counterclockwise direction in FIG. 3), the paper P is drawn along the processing tray 30, and the trailing edge is aligned by the abutting portion 30a. The abutting portion 30a is not continuously formed over the entire area in the paper width direction, but is partially formed with a notch. At this time, the upper part of the paper P is nipped by the second discharge roller pair 29, and the front end of the paper P protrudes from the second discharge roller pair 29 onto the discharge tray 50. When the paper P is pulled along the processing tray 30, the paper P is nipped in a state where the discharge roller 29a is pressed against the discharge roller 29b only by its own weight so that the paper P is not pulled more than necessary. To do.

  When the acceptance of the paper P for one bundle is completed, the stapler 40 is moved to the notch position of the abutting portion 30a to insert the rear end of the paper bundle into the staple portion 40a, and the staple portion 40a binds the paper bundle. Processing is performed. After the sheet bundle is bound by the staple unit 40a, the sheet bundle is conveyed upward along the processing tray 30 by rotating the second discharge roller pair 29 in the normal direction (in the direction of the arrow in FIG. 3), and the discharge tray 50 Discharged to the top. When the sheet bundle is discharged to the discharge tray 50, not only the weight of the roller holder 31 but also the roller holder 31 is urged downward by a biasing member such as a spring so that the discharge roller 29a is pressed against the discharge roller 29b. As a result, the sheet bundle is nipped with a stronger force than when the sheet P is pulled in, so that the sheet bundle can be reliably discharged to the discharge tray 50.

  When the shift discharge is set, when the second discharge roller pair 29 is driven to discharge the sheet bundle to the discharge tray 50, the roller holder 31 is first moved to the retracted position. After that, the side edge alignment cursor 60 is arranged at a position (shift position) shifted by a predetermined amount from the position where the paper P is received (reference position) or from the reference position in a direction orthogonal to the discharge direction (paper width direction). Then, the roller holder 31 is moved to the contact position to discharge the paper. Thus, the sheet bundle is alternately discharged to the reference discharge position P1 on the discharge tray 50 and the shift discharge position P2 shifted from the reference discharge position P1 by a predetermined amount in the direction orthogonal to the discharge direction (paper width direction). When the sheet bundle is discharged onto the discharge tray 50 (see FIG. 2), the sheet bundle is alternately stacked in the sheet width direction and sorted. Details of the reference discharge position P1 and the shift discharge position P2 will be described later.

  FIG. 4 is a block diagram illustrating a control path of the image forming system including the image forming apparatus 100 and the sheet post-processing apparatus 20. Note that the control unit 70 itself is complicated because various controls of each part of the apparatus are performed in using the image forming system. Therefore, in FIG. 4, portions of the control unit 70 and the sheet post-processing device 20 that are necessary for carrying out the present invention are mainly described. Here, the entire image forming system is controlled using the control unit 70 provided in the image forming apparatus 100, but a control unit may be provided in the sheet post-processing apparatus 20.

  The control unit 70 includes a central processing unit (CPU) 71 as a central processing unit, a read only memory (ROM) 72 that is a read-only storage unit, a random access memory (RAM) 73 that is a readable / writable storage unit, And at least a temporary storage unit 74 for storing image data and the like, a counter 75, and a plurality of (here, two) I / Fs (interfaces) 76. A control signal is transmitted to each device in the processing device 20 and an input signal from the operation unit 80 is received.

  The ROM 72 stores data that cannot be changed, such as system control programs and numerical values necessary for control. The RAM 73 stores necessary data generated during system control, data temporarily required for control, and the like. Further, the ROM 72 (or RAM 73) stores a reference conveyance pulse value transmitted to a roller drive motor (not shown) from the detection of the leading edge of the paper P by the carry-in detection sensor (not shown) until the paper carry-in roller is stopped. Is also remembered.

  The counter 75 counts the number of sheets printed on the image forming apparatus 100 and counts the number of sheets P carried into the sheet post-processing apparatus 20 from the image forming apparatus 100 based on a detection signal of the carry-in detection sensor. Alternatively, the number of sheets of paper P carried on the processing tray 30 is counted based on a detection signal of the paper detection sensor 28 disposed on the upstream side of the processing tray 30 with respect to the paper transport direction. Note that the number of times may be stored in the RAM 73, for example, without providing the counter 75 separately.

  In addition, the control unit 70 transmits a control signal from the CPU 71 to the respective units and apparatuses in the system including the image forming apparatus 100 and the sheet post-processing apparatus 20 through the I / F 76. In addition, a signal indicating the state and an input signal are transmitted from each part or device to the CPU 71 through the I / F 76. Examples of each part and device controlled by the control unit 70 include, for example, a sheet conveying unit 5, an image forming unit 6, a fixing device 7 (see FIG. 1) of the image forming apparatus 100, and punch hole formation of the sheet post-processing apparatus 20. Examples of the apparatus 21 include a first discharge roller pair 27, a second discharge roller pair 29, a processing tray 30, a stapler 40, and a side edge alignment cursor 60.

  The operation unit 80 is provided with a liquid crystal display unit 81, LEDs 82 indicating various states, and a numeric keypad 83. The user operates the operation unit 80 to input an instruction, whereby the image forming apparatus 100, paper post-processing is performed. Various settings of the apparatus 20 are performed, and various functions such as an image forming function and a post-processing function are executed. The liquid crystal display unit 81 displays the system status, displays the image formation status and the number of prints, and can be used as a touch panel for various settings such as functions such as double-sided printing and black-and-white reversal, magnification setting, and density setting. . The numeric keypad 83 is used for setting the number of prints and for inputting a transmission destination FAX number when the image forming apparatus 100 has a FAX function.

  In addition, the operation unit 80 includes a start button for instructing the user to start image formation, a stop / clear button used when the image formation is stopped, and other settings for the system to default states. A reset button or the like is provided.

  FIG. 5 is a flowchart showing an example of punch hole formation processing and shift discharge control in the paper post-processing apparatus 20 of the present invention. The punch hole forming process and the shift discharge procedure will be described along the steps of FIG. 5 with reference to FIGS.

  When the user inputs a print instruction from the operation unit 80 (see FIG. 4) or the personal computer setting screen (operation terminal) (step S1), the control unit 70 determines whether punch hole formation processing is set. (Step S2). If the punch hole forming process is set (YES in step S2), the punch hole forming device 21 forms a punch hole at a predetermined position along one side edge in a direction parallel to the transport direction. (Step S3). As a method for setting the punch hole formation position, for example, there is a method of transmitting the punch hole position information calculated from the paper size information input from the operation unit 80 or the personal computer setting screen to the control unit 70.

  Next, the control unit 70 determines whether or not the binding process is set (step S4). If the binding process is set (YES in step S4), after a predetermined number of sheets P are stacked on the processing tray 30, the binding process is executed by the stapler 40 (step S5).

  Next, the control unit 70 determines whether or not shift discharge is set (step S6). If shift discharge is set (YES in step S6), it is determined whether or not punch holes are formed in the paper P (step S7). If no punch hole is formed in the paper P (NO in step S7), as shown in FIG. 6, the straight line O is the discharge tray 50 with reference to the straight line O passing through the center of the paper in the direction orthogonal to the transport direction. From the reference discharge position P1 for discharging to a position overlapping with the center in the width direction (position conveyed by the image forming apparatus) and the front side in the paper width direction (upward in FIG. 6) and the front side in the paper width (downward in FIG. 6) Are shifted to two shift discharge positions P2 shifted by a predetermined amount S1 (for example, 15 mm), and the sheets are placed on the discharge tray 50 in the order of one shift discharge position P2, the other shift discharge position P2,. The bundle is discharged (step S8).

  On the other hand, when the punch hole is formed in the paper P (YES in step S7), as shown in FIG. 7, the front side of the apparatus of the paper P on which the punch hole is formed from the reference discharge position P1 and the reference discharge position P1, as shown in FIG. Displacement by shifting to a shift discharge position P2 shifted by a predetermined amount S2 (for example, 20 mm) to the rear side of the apparatus (upward in FIG. 7) which is opposite to the side edge direction (lower side in FIG. 7) The sheet bundle is discharged onto the tray 50 (step S9).

  When the sheet bundle discharged to the reference discharge position P1 is shifted to the shift discharge position P2 and discharged after the sheet bundle is discharged, the subsequent sheet bundle has the leading end protruded onto the discharge tray 50 and the reference discharge position P1. Then, the paper is moved in the paper width direction (upward in FIG. 7) and discharged to the shift discharge position P2.

  8A and 8B are plan views showing how the sheet bundle is discharged to the reference discharge position P1 and the shift discharge position P2. 8A and 8B show a case where four sheets of sheet bundles are discharged continuously from the right to the left in the drawing. In practice, the sheet bundles are discharged in an overlapping manner, but here, for convenience of explanation, a state where they are arranged side by side is shown.

  8A shows a sheet bundle at a reference discharge position P1 and a shift discharge position P2 shifted by a predetermined amount to the front side of the apparatus (lower side in FIG. 8A), which is the side edge direction of the paper P in which the punch holes 90 are formed. A configuration (comparative example) opposite to that of the present invention that alternately discharges is shown. In this configuration, when the fourth sheet bundle is shifted from the reference discharge position P1 to the shift discharge position P2, the corner E1 of the sheet bundle located on the downstream side in the shift direction has already been discharged to the shift discharge position P2. There is a risk of being caught in the punch hole 90 of the second sheet bundle.

  8B shows the reference discharge position P1 and the rear side of the apparatus (upward in FIG. 8B) which is opposite to the side edge direction of the front side (lower side of FIG. 8B) of the paper P on which the punch hole 90 is formed. The structure of this invention which discharges | emits alternately to the shift discharge position P2 shifted by the predetermined amount is shown. In this configuration, when the fourth sheet bundle is shifted from the reference discharge position P1 to the shift discharge position P2, the corner E2 located on the downstream side in the shift direction is the three parts that have already been discharged to the reference discharge position P1. It does not cross the punch hole 90 of the sheet bundle of eyes, and does not get caught in the punch hole 90 of the sheet bundle of the third copy.

  If shift discharge is not set (NO in step S6), all the sheet bundles are discharged to the reference discharge position P1 (step S10). Thereafter, it is determined whether or not the predetermined number of printed sheets has been completed (step S11). If printing has been completed, the process is terminated. If printing continues, the process returns to step S2, and the same processing is repeated thereafter (steps S2 to S11).

  By performing the control as described above, when performing the shift discharge to the paper P in which the punch hole 90 is formed, the side edge or corner of the paper bundle moving to the shift discharge position P2 is already at the reference discharge position P1. The punched hole 90 of the discharged sheet bundle is not caught. Therefore, the sheet bundle discharged onto the discharge tray 50 is not pushed out in the discharge direction or the direction orthogonal to the discharge direction (front-rear direction of the apparatus) by the movement of the subsequent sheet bundle, and the sheet bundle is misaligned or the discharge tray 50 Can be effectively prevented from falling.

  In addition, when performing the shift discharge to the paper P in which no punch hole is formed, the paper bundle is alternately discharged to the two shift discharge positions P2 shifted from the reference discharge position P1 to the rear side and the front side in the paper width direction. Therefore, the sheet bundle is discharged symmetrically about the reference discharge position P1 with respect to the direction orthogonal to the discharge direction. Thereby, the sheet bundle discharged onto the discharge tray 50 can be stably stacked.

  Although the shift discharge procedure in the case where the punch hole 90 is formed along the side edge on the front side of the paper has been described here, the punch hole 90 is formed along the side edge on the back side of the paper. The shift discharge in this case can be performed in exactly the same manner. In this case, as shown in FIG. 9, a reference discharge position P1 where the straight line O and the center in the width direction of the discharge tray 50 overlap with each other with reference to a straight line O passing through the center in the direction orthogonal to the sheet conveyance direction, and a reference discharge position. The same effect as described above can be obtained by discharging the sheet bundle to the shift discharge position P2 shifted by a predetermined amount from P1 toward the front side in the sheet width direction (downward in FIG. 9).

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of this invention. For example, in the above embodiment, the configuration in which the image forming apparatus 100 and the paper post-processing apparatus 20 are directly connected has been described as an example. However, a slip sheet is inserted between the image forming apparatus 100 and the paper post-processing apparatus 20. The present invention can also be applied to a configuration in which an insert device is mounted.

  Further, the shift amounts S1 and S2 at the time of shift discharge can be set as appropriate according to the paper size, the size of the discharge tray 50, and the like.

  The present invention is applicable to a sheet post-processing apparatus capable of forming punch holes along the sheet conveying direction. By using the present invention, when performing shift discharge to a sheet having punch holes formed along the sheet conveying direction, sheet extrusion or misalignment due to interference between the punch holes and the side edge or corner of the subsequent sheet It is possible to provide a sheet post-processing apparatus and an image forming system including the same.

Claims (4)

A punch hole forming device that forms punch holes along the side edge of the sheet parallel to the sheet conveying direction;
A processing tray disposed downstream of the punch hole forming device in the sheet conveying direction, for receiving and stacking a predetermined number of sheets;
A discharge tray disposed on the downstream side of the processing tray in the sheet conveying direction and for discharging sheets stacked on the processing tray;
In a sheet post-processing apparatus comprising:
The processing tray moves the sheet in a direction perpendicular to the discharge direction with the leading end of the sheet protruding on the discharge tray, and thereby the reference discharge position on the discharge tray and the discharge direction from the reference discharge position. And a shift discharge position for discharging the sheet to a shift discharge position shifted by a predetermined amount in a direction orthogonal to
When punch holes are formed in the sheet to be shifted and discharged, the reference discharge position and the shift discharge position shifted in the direction opposite to the sheet side edge where the punch holes are formed from the reference discharge position, A sheet post-processing apparatus that discharges a sheet.   When punch holes are not formed in the sheet to be shifted, the sheets are alternately discharged to two shift discharge positions shifted by a predetermined amount on both sides in the direction orthogonal to the discharge direction with the reference discharge position as the center. The sheet post-processing apparatus according to claim 1.   The sheet post-processing apparatus according to claim 1, wherein the reference discharge position is a position where a straight line passing through a center in a direction orthogonal to a sheet conveyance direction and a center in the width direction of the discharge tray overlap. The sheet post-processing apparatus according to claim 1;
An image forming apparatus connected to the sheet post-processing apparatus to form an image on the sheet and to convey the sheet on which the image is formed to the sheet post-processing apparatus;
A control unit for controlling the sheet post-processing apparatus and the image forming apparatus;
An image forming system.