Patent Publication Number: US-2012025442-A1

Title: Sheet processing apparatus and sheet processing method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the priority of U.S. Provisional Application No. 61/368,606, filed on Jul. 28, 2010, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     Embodiments described below relate to a sheet processing apparatus and a sheet processing method of performing a post-process such as stapling for a sheet discharged from an image forming apparatus such as a copier, a printer, a multifunction peripheral (MFP) or the like. 
     BACKGROUND 
     An image forming apparatus (for example, an MFP) is connected to a sheet processing apparatus on the rear side thereof in order to post-process a sheet after an image is formed thereon. The sheet processing apparatus is called a finisher, and staples and sorts sheets sent from the MFP so as to perform discharging to a storage tray. 
     The finisher is provided with transverse alignment plates for controlling positions of sheets in the width direction, aligns the sheets, and carries the sheets to a stapler so as to staple. The transverse alignment plates are also used to sort and discharge the sheets. 
     Meanwhile, the sheet processing apparatus in the related art aligns the sheets using the transverse alignment plates and discharges the sheets to the storage tray; however, there are cases where the sheets are not in order during the discharge, and thus cannot be properly discharged to the storage tray. Therefore, a new improvement is required in order to increase the alignment of sheets. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a configuration diagram illustrating a sheet processing apparatus and an image forming apparatus according to an embodiment. 
         FIG. 2  is a configuration diagram of the sheet processing apparatus (finisher) according to an embodiment. 
         FIG. 3  is a perspective view when the finisher is viewed from an outlet side according to an embodiment. 
         FIG. 4  is a perspective view illustrating transverse alignment plates and a storage tray of the finisher according to an embodiment. 
         FIG. 5  is a plan view illustrating a driving portion of inner alignment plates according to the embodiment. 
         FIG. 6  is a plan view illustrating a driving portion of outer alignment plates according to the embodiment. 
         FIG. 7A  and  FIG. 7B  are plan views illustrating a discharge operation of a sheet according to the embodiment. 
         FIG. 8  is a block diagram illustrating a control system of the image forming apparatus and the finisher. 
     
    
    
     DETAILED DESCRIPTION 
     A sheet processing apparatus according to an embodiment includes, a post-processing unit that post-processes a sheet carried from an image forming apparatus, a sheet discharge unit that discharges the post-processed sheet to an outlet, a storage tray that stacks the sheet discharged from the outlet and can move in the vertical direction, and a first transverse alignment portion that is provided at the storage tray and aligns the sheet discharged from the outlet from the width direction. 
     Hereinafter, a sheet processing apparatus according to an embodiment will be described in detail with reference to the drawings. In addition, like numbers reference like elements in the drawings. 
       FIG. 1  is a configuration diagram illustrating a sheet processing apparatus and an image forming apparatus. In  FIG. 1 , an image forming apparatus  100  is, for example, an MFP (Multi-Function Peripheral), a printer, or a copier. A sheet processing apparatus  200  post-processing a sheet is disposed so as to be adjacent to the image forming apparatus  100 . The sheet processing apparatus  200  is referred to as a finisher  200  hereinafter. 
     A sheet on which an image is formed by the image forming apparatus  100  is carried to the finisher  200 . The finisher  200  performs a post-process (finishing) for the sheet supplied from the image forming apparatus  100 , and, for example, performs stapling, sorting, or the like for the sheet. 
     A document table is disposed on a main body  1  of the image forming apparatus  100 , and an automatic document feeder (ADF)  2  is provided so as to be opened and closed on the document table. An operation panel  3  is provided on the upper portion of the main body  1 . The operation panel  3  has various operation keys  4 , and a touch panel type display portion  5 . 
     The main body  1  has a scanner unit  6  and a printer unit  7  therein, and a plurality of cassettes  8  containing sheets with various kinds of sizes is provided at the lower portion of the main body  1 . The scanner unit  6  reads a document sent by the ADF  2 , or a document placed on the document table. 
     The printer unit  7  includes a photoconductive drum, laser, and the like, exposes a surface of the photoconductive drum by scanning the surface with laser beams from the laser, and forms an electrostatic latent image on the photoconductive drum. A charger, a developing device, a transfer device, and the like are disposed around the photoconductive drum, the electrostatic latent image on the photoconductive drum is developed by the developing device, and a toner image is formed on the photoconductive drum. The toner image is transferred onto a sheet by the transfer device. The sheet onto which the toner image is transferred is heated by a fixing device, and the toner image is fixed to the sheet. The configuration of the printer unit  7  is not limited to the above-described example but may take a variety of forms. 
     The sheet on which the image is formed by the printer unit  7  is carried to the finisher  200  by a discharge roller  9 . The finisher  200  has, for example, a staple unit  10  which staples a bundle of sheets. The sheets post-processed by the finisher  200  are discharged to a storage tray  41  or a fixed tray  42 . The storage tray  41  can move in the vertical direction. 
       FIG. 2  is a configuration diagram of the finisher  200 . The staple unit  10  has a stand-by tray  11 , a process tray  12 , and a stapler  13 . The sheet S discharged by the discharge roller  9  of the image forming apparatus  100  is received by an inlet roller  14  provided at an entrance of the staple unit  10 . The inlet roller  14  includes an upper roller and a lower roller, and is driven by a motor. 
     A paper feeding roller  15  is provided downstream of the inlet roller  14 , and the sheet S received by the inlet roller  14  is sent to the stand-by tray  11  via a paper feeding roller  15 . The paper feeding roller  15  includes an upper roller and a lower roller, and the paper feeding roller  15  is driven by a motor. The process tray  12  which stacks the sheet S dropping from the stand-by tray  11  is disposed at the lower side of the stand-by tray  11 . 
     The stand-by tray  11  stacks the sheet S and has a structure capable of being opened. When a predefined number of sheets S are accumulated, the stand-by tray  11  is opened, and the sheet S drops toward the process tray  12  due to the self weight or a dropping assistance member which forces the sheet S to drop. The process tray  12  supports the sheet S while the stapler  13  staples the sheet S. 
     The dropped sheet on the process tray  12  is guided to the stapler  13  by a roller  17  and undergoes stapling. The roller  17  is driven by a motor, and rotates in the reverse direction when the sheet S is guided to the stapler  13  and the stapled sheet S is discharged. 
     When the sheet is stapled, a plurality of dropped sheets S to the process tray  12  from the stand-by tray  11  are aligned in the longitudinal direction which is a carrying direction, also aligned in the transverse direction perpendicular to the carrying direction, and then stapled. A transverse alignment portion  23  is provided in order to align the sheets S in the transverse direction. The transverse alignment portion  23  aligns and sorts the sheets S. The stapler  13  and the transverse alignment portion  23  constitute a post-processing unit, and perform a post-process such as stapling or sorting. 
     In addition, in order to assist the sheet S in dropping to the process tray  12 , a rotatable paddle  18  is provided at the position where the rear end of the sheet S drops. The paddle  18  is installed at a rotation shaft, makes the sheet S dropping from the stand-by tray  11  fall on the process tray  12 , and sends the sheet S in the direction of the stapler  13 . 
     A stopper  19  which limits the rear end position of the sheet S is provided at the end part of the stapler  13  side of the process tray  12 . Further, a carrying belt  20  is provided so as to carry the sorted or stapled sheets S to the storage tray  41 . The carrying belt  20  hangs between pulleys  21  and  21 , and the carrying belt  20  is provided with a claw member  20   a  which suspends and sends the rear end of the sheet S. 
     When the carrying belt  20  rotates in an arrow t direction, the sheet S is discharged from an outlet  24  to the storage tray  41 . The storage tray  41  moves in the vertical direction and receives the sheet S by a motor. The carrying belt  20  and the claw member  20   a  constitute a sheet discharge unit for guiding the stapled sheet S to the outlet  24 . 
     In addition, if the sheets S stacked in the stand-by tray  11  are not stapled but are discharged to the storage tray  41 , the sheets S do not drop to the process tray  12  but are discharged by a rotation roller  16 . Further, the sheet S which is not required to be stapled may be discharged to the fixed tray  42 . A carrying path is provided in order to guide the sheet S to the fixed tray  42 . An assistance arm  25  is installed so as to rock at an installation shaft of the upper roller of the paper feeding roller  15 . The assistance arm  25  protrudes toward the discharge side of the paper feeding roller  15 , and tightly presses the rear end side of the sheet S discharged from the paper feeding roller  15  toward the stand-by tray  11  so that the rear end side is not floated. 
       FIG. 3  is a perspective view when the finisher  200  is viewed from an arrow A direction in  FIG. 2 . The process tray  12  is seen from an opening portion  24  of the finisher  200 . The carrying belt  20  is disposed at the central part of the process tray  12 , and transverse alignment plates  23   a  and  23   b  of the transverse alignment portion  23  are disposed at the left and right end parts of the process tray  12 . However, in  FIG. 3 , the transverse alignment plate  23   b  is not seen since the transverse alignment plate  23   b  is hidden in the finisher main body. 
     The sheet S discharged from the finisher  200  is discharged to the storage tray  41  and stacked. In addition, the sheet S may be discharged singly, or may be discharged as a bundle of stapled sheets. The storage tray  41  is provided with a transverse alignment portion  32  which aligns the discharged sheets in the width direction. The transverse alignment portion  32  has a pair of transverse alignment plates  32   a  and  32   b  which can move in the direction perpendicular to the discharge direction of the sheets. In  FIG. 3 , the transverse alignment plate  32   a  is hidden by the sheet S. 
       FIG. 4  is a perspective view illustrating a configuration of main portions according to the embodiment, and is a diagram when the storage tray  41  is viewed from the process tray  12  side. In  FIG. 4 , a shaft  26  is disposed to be perpendicular to the carrying direction of the sheet S, the pulley  21  ( FIG. 2 ) is installed at the intermediate part of the shaft  26 , and the carrying belt  20  hangs between the pulley  21  and the pulley  22 . The carrying belt  20  is rotated by a motor  30 , and rotatably moves along the discharge direction of the sheet in a circulated manner. Further, a plurality of discharge rollers  27  is installed at the shaft  26  and rotates when the sheet S is discharged to the storage tray  41 . 
     The process tray  12  is provided with the transverse alignment portion  23 . The transverse alignment portion  23  has the pair of transverse alignment plates  23   a  and  23   b  provided at both sides of the process tray  12 . The transverse alignment plates  23   a  and  23   b  are slidable in the width direction (direction perpendicular to the carrying direction) of the sheet. The transverse alignment plates  23   a  and  23   b  align dropped sheets from the stand-by tray  11  ( FIG. 2 ). The transverse alignment plates  23   a  and  23   b  are moved in parallel to the shaft  26  by the rotation of motors  291  and  292 . The motors  291  and  292  are installed at a frame  31 . 
     In addition, the storage tray  41  is provided with the transverse alignment plates  32   a  and  32   b  constituting the transverse alignment portion  32 . The transverse alignment plates  32   a  and  32   b  can move in the direction perpendicular to the discharge direction of the sheet. 
     The sheets S which are post-processed by the finisher  200  are aligned by the transverse alignment plates  23   a  and  23   b  for the post-process and then are discharged to the storage tray  41 , and further are aligned by the transverse alignment plates  32   a  and  32   b  on the storage tray  41 . The transverse alignment plates  23   a  and  23   b  may move in synchronization with the transverse alignment plates  32   a  and  32   b . In addition, the transverse alignment plates  32   a  and  32   b  move with the passage of a preset time, that is, with some delay time after the transverse alignment plates  23   a  and  23   b  align the sheet S through the movement. The transverse alignment plates  23   a  and  23   b  and the transverse alignment plates  32   a  and  32   b  are respectively driven by individual driving sources. 
     In addition, in the following description, for convenience, the transverse alignment plates  23   a  and  23   b  are referred to as inner alignment plates, and the transverse alignment plates  32   a  and  32   b  are referred to outer alignment plates. 
       FIG. 5  is a plan view illustrating the transverse alignment portion  23 , and mainly shows a configuration of a driving portion of the inner alignment plates  23   a  and  23   b .  FIG. 6  is a plan view illustrating the transverse alignment portion  32 , and mainly shows a configuration of a driving portion of the outer alignment plates  32   a  and  32   b.    
     In  FIG. 5 , the transverse alignment portion  23  includes the pair of inner alignment plates  23   a  and  23   b  disposed at both sides of the process tray  12 , racks  23   c  and  23   d  coupled with the inner alignment plates  23   a  and  23   b , and gears  23   e  and  23   f  engaged with the racks  23   c  and  23   d.    
     The motors  291  and  292  which are driving sources are provided in order to rotate the gears  23   e  and  23   f . The rotation of the motor  291  allows the gear  23   e  to rotate, the rack  23   c  to move, and the inner alignment plate  23   a  to move in an arrow A or an arrow B direction. In addition, a gear  23   g  is provided between the motor  292  and the gear  23   f.    
     The rotation of the motor  292  allows the gear  23   g  and the gear  23   f  to rotate, the rack  23   d  to move, and the inner alignment plate  23   b  to move in the arrow A or the arrow B direction. The inner alignment plates  23   a  and  23   b  can respectively move independently from each other in the direction (A and B directions) perpendicular to the sheet carrying direction. 
     Further, sensors  23   h  and  23   i  are provided around the inner alignment plates  23   a  and  23   b , and detect home positions of the inner alignment plates  23   a  and  23   b . The home positions of the inner alignment plates  23   a  and  23   b  are, for example, positions where the inner alignment plates  23   a  and  23   b  move to the end in the B direction, and move in the arrow A direction from the home positions depending on the sizes of sheets. If stepping motors are used as the motors  291  and  292 , the movement distances of the inner alignment plates  23   a  and  23   b  can be set through the management of the number of rotations of the motors  291  and  292 . 
     When the sheet S drops to the process tray  12 , the inner alignment plates  23   a  and  23   b  are located at the stand-by positions in the arrow B direction, and are spaced apart from the sheet S in the width direction. In order to correct the misalignment in the width direction of the dropped sheet S on the process tray  12 , the inner alignment plates  23   a  and  23   b  move in the arrow A direction and align the sheet S with the sheet S located therebetween in the width direction. 
     In addition, when the transverse alignment portion  23  sorts the sheet S, the inner alignment plates  23   a  and  23   b  stand by at the position through the movement in the arrow B direction, and, for example, with respect to one inner alignment plate  23   a , the sheet S is tightly pressed to the inner alignment plate  23   a  by moving the other inner alignment plate  23   b . Alternatively, with respect to the other inner alignment plate  23   b , the sheet S is tightly pressed to the other inner alignment plate  23   b  by moving the one inner alignment plate  23   a.    
       FIG. 6  is a plan view illustrating the transverse alignment portion  32 , and mainly shows a configuration of a driving portion of the outer alignment plates  32   a  and  32   b . In  FIG. 6 , the transverse alignment portion  32  has the pair of the outer alignment plates  32   a  and  32   b  of which a part protrudes on the upper surface of the storage tray  41 . In addition, the storage tray  41  is provided with racks  32   c  and  32   d  coupled with the outer alignment plates  32   a  and  32   b , and gears  32   e  and  32   f  engaged with the racks  32   c  and  32   d.    
     Motors  331  and  332  which are driving sources are provided in order to rotate the gears  32   e  and  32   f . The rotation of the motor  331  allows the gear  32   e  to rotate, the rack  32   c  to move, and the outer alignment plate  32   a  to move in the arrow A or the arrow B direction. In addition, a gear  32   g  is provided between the motor  332  and the gear  32   f.    
     The rotation of the motor  332  allows the gear  32   g  and the gear  32   f  to rotate, the rack  32   d  to move, and the outer alignment plate  32   b  to move in the arrow A or the arrow B direction. The outer alignment plates  32   a  and  32   b  can respectively move independently from each other in the direction perpendicular to the sheet carrying direction. 
     Further, sensors  32   h  and  32   i  are provided around the outer alignment plates  32   a  and  32   b , and detect home positions of the outer alignment plates  32   a  and  32   b . The home positions of the outer alignment plates  32   a  and  32   b  are, for example, positions where the outer alignment plates  32   a  and  32   b  move to the end in the B direction, and move in the arrow A direction from the home positions depending on the sizes of sheets. If stepping motors are used as the motors  331  and  332 , the movement distances of the outer alignment plates  32   a  and  32   b  can be set through the management of the number of rotations of the motors  331  and  332 . 
     The outer alignment plates  32   a  and  32   b  stand by at the positions through the movement in the arrow B direction. If the sheet S is discharged to the storage tray  41 , the outer alignment plates  32   a  and  32   b  move in the arrow A direction and align the sheet S with the sheet S located therebetween in the width direction. 
     In addition, if sorted sheets are discharged, the outer alignment plates  32   a  and  32   b  align the sheets S in the width direction through the movement of the outer alignment plate  32   a  and the outer alignment plate  32   b.    
     Therefore, when the finisher  200  staples or sorts the sheets S and discharges the sheets S to the storage tray  41 , the sheets on the storage tray  41  are aligned in the width direction by the outer alignment plates  32   a  and  32   b , and thus it is possible to prevent the discharged sheets S from being in disorder. 
     If driving timings of the motors  291 ,  292 ,  331  and  332  are controlled such that the outer alignment plates  32   a  and  32   b  move with some delay time after the inner alignment plates  23   a  and  23   b  move, the alignment is further improved. 
       FIG. 7A  is a plan view illustrating operations of the inner alignment plates  23   a  and  23   b  and the outer alignment plates  32   a  and  32   b  when the sheets S are transversely aligned and are discharged to the storage tray  41 . 
     For example, assuming that the sheets S are moved close to the central part of the process tray  12  by the inner alignment plates  23   a  and  23   b , aligned, and discharged. If the sheets S are discharged to the storage tray  41 , the outer alignment plates  32   a  and  32   b  move the sheets S close to the central part of the storage tray  41  and align the sheets S. The outer alignment plates  32   a  and  32   b  move in the arrow A direction from the stand-by positions (dotted lines). 
     The inner alignment plates  23   a  and  23   b  and the outer alignment plates  32   a  and  32   b  change their aligning positions depending on the sizes of the sheets S. The outer alignment plates  32   a  and  32   b  move in the same direction so as to correspond with movement of the inner alignment plates  23   a  and  23   b . In addition, the positions of the outer alignment plates  32   a  and  32   b  are set to correspond with the positions of the inner alignment plates  23   a  and  23   b . In other words, in which direction the inner alignment plates  23   a  and  23   b  move and to which position the inner alignment plates  23   a  and  23   b  move are known in advance, and thus the movement and the position of the outer alignment plates  32   a  and  32   b  can be set to correspond with the movement of the inner alignment plates  23   a  and  23   b.    
       FIG. 7B  is a plan view illustrating operations of the inner alignment plates  23   a  and  23   b  and the outer alignment plates  32   a  and  32   b  when the sheets S are sorted and are discharged to the storage tray  41 . For example, be assumed that the inner alignment plates  23   a  and  23   b  sort the sheets S 1  and S 2  to the central part of the process tray  12  and discharge the sorted sheets. The outer alignment plates  32   a  and  32   b  respectively move from the stand-by positions marked with the dotted lines to the positions marked with the solid lines. 
     In addition, it is assumed that, during the sorting of the sheets, the sort width defined by the inner alignment plate  23   a  when sorting the sheet S 1  and the inner alignment plate  23   b  when sorting the sheet S 2  is W 1 . If the outer alignment plates  32   a  and  32   b  move such that a total width W 2  of the sheet S 1  and the sheet S 2  discharged to the storage tray  41  becomes W 1 ≅W 2 , the alignment between the sheet S 1  and the sheet S 2  after being sorted becomes favorable. 
       FIG. 8  is a block diagram illustrating a control system of the image forming apparatus  100  and the finisher  200 . In  FIG. 8 , a main control unit  101  includes a CPU  102 , a ROM  103 , and a RAM  104 . The CPU  102  controls the image forming apparatus  100  according to a control program stored in the ROM  103 . In addition, the main control unit  101  controls the operations of the ADF  2 , the scanner unit  6 , and the printer unit  7  in response to an operation of the operation panel  3 . The RAM  104  temporarily stores control data and is used for calculation work during the control. 
     The operation panel  3  has a plurality of operation keys  4  and the touch panel type display portion  5 , and gives various instructions for forming images. For example, an instruction for the number of copies is given using the operation keys  4 , and instructions for a sheet size, the kind of sheet, stapling, sorting, and the like are given by operating the touch panel of the display portion  5 . 
     A finisher control unit  201  controls an operation of the finisher  200  and an operation of a sheet discharge. The finisher control unit  201  is connected to the main control unit  101 , and transits information along with the main control unit  101 , and the image forming apparatus  100  and the finisher  200  work in cooperation. 
     The finisher control unit  201  drives the motor  34  which moves the storage tray  41  in the vertical direction, and controls the height of the storage tray  41  so as to match the height of the process tray  12 . In addition, if there is an instruction for stapling from the operation panel  3 , the stapling is executed by driving the motor  35  which controls a position of the stapler  13 . Further, the transverse alignment and the sorting of the sheets S are executed by driving the motors  291  and  292  which drive the inner alignment plates  23   a  and  23   b . The transverse alignment of the sheets S discharged on the storage tray  41  is executed by driving the motors  331  and  332  which drive the outer alignment plates  32   a  and  32   b.    
     According to the embodiment described above, possible to align sheets discharged to the storage tray and stack the sheets so as not to be in disorder. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. Indeed, the novel apparatus and methods described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the apparatus and methods described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.