Patent Publication Number: US-8113510-B2

Title: Sheet processing apparatus and image forming apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sheet processing apparatus, and more particularly, to a sheet processing apparatus that regulates, in a width direction, a position of a sheet to be processed, and to an image forming apparatus including the sheet processing apparatus. 
     2. Description of the Related Art 
     Heretofore, as an image forming apparatus such as a copier, a printer, a facsimile machine, and a multifunctional printer, there is known an image forming apparatus main body which is provided with a sheet processing apparatus, where sheets are delivered from the image forming apparatus main body after image formation to the sheet processing apparatus which implements a process such as a binding process for the sheets. In the sheet processing apparatus, the sheets delivered from the image forming apparatus main body are transported to a sheet processing portion. Then, the sheet processing portion implements, for the delivered sheets, processes such as a stacking/aligning operation of stacking and aligning the sheets, and a stapling operation of binding the sheets. 
     As a conventional sheet processing apparatus, an apparatus has been disclosed, in which a sheet moving device moves the sheets in a width direction intersecting with a sheet transporting direction, and allows side edges of the sheets to abut against an abutting member, to thereby align the sheets. Here, in the sheet processing apparatus, a sheet holding-down member that suppresses curling of such side edge portions of the sheets is placed in the vicinity of the abutting member (Japanese Patent Application Laid-Open No. 2005-306528). 
     However, the sheet holding-down member is fixed with respect to the width direction, and hence a distance between the sheet moving device and the sheet holding-down member at the time when the sheet moving device aligns sheets of a large size becomes larger than a distance between the sheet moving device and the sheet holding-down member at the time when the sheet moving device aligns sheets of a small size. Hence, in the case of aligning the sheets of the large size, there is a fear that the sheets may buckle between the sheet moving device and the sheet holding-down member to thereby adversely affect alignment characteristics, compared with the case of aligning the sheets of the small size. 
     SUMMARY OF THE INVENTION 
     Therefore, the present invention has been made in consideration of the actual circumstances as described above. It is an object of the present invention to provide a sheet processing apparatus capable of suppressing buckling of sheets in a width direction thereof regardless of a size of the sheet when aligning the sheets in the width direction thereof, and to provide an image forming apparatus including the sheet processing apparatus. 
     The present invention provides a sheet processing apparatus that processes sheets transported in a predetermined transport direction and stacked on a processing tray, the sheet processing apparatus including: a sheet moving device configured to be brought into contact with an upper surface of a sheet stacked on the processing tray and to be moved in a width direction intersecting with the predetermined transport direction to move the sheet in the width direction; an alignment member against which a side edge of the sheet moved in the width direction by the sheet moving device is brought into abutment, to align the sheet; and a guide member configured to hold down the sheet from above at a predetermined position between the sheet moving device and the alignment member when the sheet moving device is in contact with the upper surface of the sheet, in which the guide member is moved integrally with the sheet moving device when the sheet moving device is moved in the width direction. 
     According to the present invention, when the sheet moving device is moved in the width direction, the guide member is moved integrally with the sheet moving device. In  this case, when aligning the sheet in the width direction, the buckling of the sheet in the width direction may be suppressed, regardless of the size of the sheet.  
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view illustrating an entire image forming system that includes a sheet processing apparatus according to an embodiment of the present invention. 
         FIG. 2  is a cross-sectional view schematically illustrating a cross section of the sheet processing apparatus. 
         FIG. 3  is a cross-sectional view schematically illustrating details of the sheet processing apparatus. 
         FIGS. 4A and 4B  are schematic views schematically illustrating operation states where a gripper unit provided in a gripper/stapler portion of the sheet processing apparatus nips a sheet bundle. 
         FIG. 5  is a plan view illustrating a configuration of the gripper/stapler portion of the sheet processing apparatus. 
         FIG. 6A  is a view illustrating a shift roller and a guide member in an alignment portion of the sheet processing apparatus. 
         FIG. 6B  is a view illustrating the guide member. 
         FIG. 7  is a view illustrating a configuration of the guide member. 
         FIGS. 8A and 8B  are views illustrating how the guide member swings upward and downward. 
         FIGS. 9A and 9B  are views illustrating motions of the guide member in a width direction. 
         FIGS. 10A and 10B  are views illustrating the motions of the guide member in the width direction. 
     
    
    
     DESCRIPTION OF THE EMBODIMENT 
     An embodiment of the present invention is described below in detail with reference to the drawings. 
       FIG. 1  is a schematic view illustrating an entire image forming system that includes a sheet processing apparatus according to the embodiment of the present invention, and  FIG. 2  and  FIG. 3  are schematic cross-sectional views of the sheet processing apparatus. As illustrated in  FIG. 1 , an image forming system  100  includes a sheet feeding apparatus A, an image forming apparatus B provided with an image forming apparatus main body B 2 , a sheet processing apparatus (hereinafter, simply referred to as “processing apparatus”) C, an original reading apparatus D, and an original transport apparatus E. 
     The original transport apparatus E transports originals, which are set on an original tray E 1 , one by one onto a platen glass of the original reading apparatus D, and delivers the originals onto a delivery tray E 2 . At this time, the original reading apparatus D reads the originals, which pass on the platen glass by the original transport apparatus E, by a reading device (not shown). Note that, the reading device includes a lamp, multiple mirrors, a lens, and an image sensor. Then, light emitted from the lamp of the reading device is reflected on a surface of an original, and is guided through the multiple mirrors and the lens to the image sensor. In this manner, an image is read by the image sensor. Image data of the original read by the image sensor is subjected to a predetermined image processing, and is transferred to an exposure control unit (not shown) of the image forming apparatus main body B 2 . 
     The exposure control unit of the image forming apparatus main body  82  outputs a laser beam according to an image signal. The laser beam is irradiated onto a photosensitive drum B 1  while being scanned by a polygon mirror. An electrostatic latent image corresponding to the scanned laser beam is formed on the photosensitive drum B 1 . The electrostatic latent image formed on the photosensitive drum B 1  is developed by a developing unit (not shown), and is visualized as a toner image. 
     The sheet feeding apparatus A includes multiple cassettes A 1 . A sheet on which the image is to be formed is transported from any one of the multiple cassettes A 1  of the sheet feeding apparatus A to a transfer portion of the image forming apparatus main body B 2 . Then, the visualized toner image is transferred, in the transfer portion, to the sheet transported from the sheet feeding apparatus A, and the image is formed on the sheet. The sheet to which the image is transferred is then subjected to a fixing process in a fixing portion. Then, the sheet which has passed through the fixing portion is transported to the processing apparatus C. The sheets transported to the processing apparatus C are subjected to a process such as binding and folding by a processing portion  9 , and are then delivered to a containing portion  10 . 
     Next, the processing apparatus C according to the embodiment of the present invention will be described based on  FIG. 1  to  FIG. 3 . 
     As illustrated in  FIG. 1 , the processing apparatus C is disposed between the image forming apparatus main body B 2  and the original reading apparatus D. The processing portion  9  including a binding device is provided on one end side of the processing apparatus C in a horizontal direction. The containing portion  10  that contains the processed sheets is provided on the other end side of the processing apparatus C. The containing portion  10  is provided in a delivery space  15  formed between the image forming apparatus main body B 2  and the original reading apparatus D. Specifically, the image forming system  100  has a so-called in-body delivery function to contain the processed sheets in the delivery space  15  between the image forming apparatus main body B 2  and the original reading apparatus D. 
       FIG. 2  is the schematic cross-sectional view illustrating the respective functional units of the processing apparatus C. As illustrated in  FIG. 2 , the processing apparatus C includes a transport portion  11  that receives and transports the sheets coming from the image forming apparatus main body B 2  and a processing tray  14  on which the sheets sent from the transport portion  11  are stacked. Further, the processing apparatus C includes an alignment portion  12  that aligns the sheets stacked on the processing tray  14 , a gripper/stapler portion  13  that implements a staple process for the aligned sheets, and the containing portion  10  having multiple stack trays  50  and  51 . 
     Next, based on  FIG. 3 , details will be described of the respective functional portions of the processing apparatus C that processes the sheets transported in a predetermined transporting direction and stacked on the processing tray  14 . 
     In the transport portion  11 , there are provided a transport path  20  that communicates with a delivery port (not shown) of the image forming apparatus main body B 2  and a transport roller pair  21  that transports the sheet along the transport path  20 . Further, a delivery roller pair  22  is provided on a delivery port  20   c  of the transport path  20 . The delivery roller pair  22  sequentially delivers the sheet to the processing tray  14  arranged below the transport path  20 . The transport path  20  includes a pair of guide plates  20   a  and  20   b  which guide the sheet. The delivery roller pair  22  transports the sheet in a transport direction X, and stacks the sheet on the processing tray  14 . The sheets delivered by the delivery roller pair  22  are placed in a state of bridging over the processing tray  14  and sheet placing surfaces  50   a  and  51  of the stack trays  50  and  51  which will be described later, and are subjected to a predetermined process. 
     In the alignment portion  12 , a stopper member  31  that aligns trailing edges of the sheets stacked on the processing tray  14  is provided. Forward and reversely rotatable shift rollers  30  contact an upper surface of the sheet stacked on the processing tray  14 , and can thereby transport the sheet in the transport direction X and a direction reverse to the transport direction X. Further, the shift rollers  30  contact the upper surface of the sheet stacked on the processing tray  14 , then move in a width direction Y (a direction indicated by the arrow Y in  FIG. 9A ) intersecting with the transport direction X, and can thereby move the sheet in the width direction Y. An alignment member  32  (refer to  FIG. 5 ) is provided on one end portion of the processing tray  14  in the width direction Y. A side edge of the sheet in the width direction (intersecting with the transport direction X), which is moved in the width direction Y by the shift rollers  30  on the processing tray  14 , is brought into abutment against the alignment member  32 , to thereby align the sheet on the processing tray  14  in the width direction Y. 
     The stopper member  31  is configured to be freely rotatable about a support shaft  31   a  as a pivot, and can be moved between an alignment position in a vertical state and a retreat position in a substantially horizontal state. The shift rollers  30  are freely rotatably provided on one end side of an arm member  33  provided so as to be capable of moving up and down about, as a pivot, a support shaft  33   a  which has a polygon-shaped cross section. The shift rollers  30  are configured to be swingable, by a rotational operation of the arm member  33 , between a contact position CP ( FIG. 8A ) in which the shift rollers  30  contacts the upper surface of the sheet stacked on the processing tray  14  and a retreat position RP ( FIG. 8B ) above the processing tray  14 . When the shift rollers  30  are located at the retreat position RP, the shift rollers  30  are retreated apart from the sheet stacked on the processing tray  14 . Note that, the arm member  33  is configured to be freely movable in the width direction Y along the support shaft  33   a , and the shift rollers  30  are moved in the width direction Y by such movement of the arm member  33 . 
     Further, for such a sheet moving device (the shift rollers  30  and the arm member  33 ) configured to move the sheet in the width direction Y, a guide member  61  that is swingable in an up-and-down direction and slidable in the width direction Y is provided as illustrated in  FIGS. 6A and 6B . Here, as illustrated in  FIG. 7 , this guide member  61  includes a holding-down guide  61   a  which holds down both end portions of the sheet in the width direction, from above. Further, the guide member  61  includes a guide holder  61   b  that holds down a center portion of the sheet from above and supports the holding-down guide  61   a  so as to be slidable in the width direction, and a spring (an elastic member)  61   c . The guide holder  61   b  is configured to be slidingly movable with respect to the holding-down guide  61   a . The spring  61   c  includes a first spring  61   c   1  and a second spring  61   c   2 . The first spring  61   c   1  is an urging device configured to urge the holding-down guide  61   a  in a direction of the alignment member  32 . The second spring  61   c   2  is an urging device configured to urge the holding-down guide  61   a  in a direction reverse to the direction of the alignment member  32 . The first spring  61   c   1  and the second spring  61   c   2  are structured as described above, and accordingly, the guide member  61  is maintained in a neutral state with respect to the shift rollers  30  and the arm member  33 . 
     When the shift rollers  30  are lifted to be moved to the retreat position RP, the guide member  61  abuts against an abutment member  62  as illustrated in  FIG. 8B , and takes an attitude capable of receiving the sheet transported from the upstream in the transport direction. At this time, the guide member  61  is on standby at a position of bringing the sheet, which is transported in the transport direction X from the upstream of the shift rollers  30 , onto the processing tray  14 . Further, when the shift rollers  30  are lowered to be moved to the contact position CP, as illustrated in  FIG. 8A , the guide member  61  serves as a curl presser that acts on the sheet in the transport direction X of the sheet and presses the curl of the sheet. When the shift rollers  30  are in contact with the upper surface of the sheet as described above, the guide member  61  holds down the sheet from above at a predetermined position between the shift rollers  30  and the alignment member  32 . Further, in this embodiment, the guide member  61  is configured so as to hold down the sheet, which is stacked on the processing tray  14 , from above at a predetermined position on an opposite side of the shift rollers  30  to the alignment member  32  in the width direction Y. 
     Further, as illustrated in  FIGS. 9A and 9B , when the shift rollers  30  and the arm member  33  are moved in the width direction Y, the guide member  61  is also moved integrally therewith. In the case of moving a small-width sheet in the width direction Y by the shift rollers  30 , a movement amount of the guide member  61  in the width direction Y is increased. In the case of the small-width sheet, an end portion of the holding-down guide  61   a  may be located at a position closer to the alignment member  32  than a side edge of the sheet. In such a case, not the side edge of the sheet but the end portion of the holding-down guide  61   a  abuts against the alignment member  32  ( FIG. 9B ). 
     However, as already described, the guide holder  61   b  is configured to be slidingly movable with respect to the holding-down guide  61   a . In such a way, even in the case where the holding-down guide  61   a  abuts against the alignment member  32 , only the guide holder  61   b  slides in the width direction Y against the spring  61   c  in a state where the holding-down guide  61   a  is maintained at a position of abutting against the alignment member  32 . In such a way, the guide holder  61   b  moves in the width direction Y until the side edge of the sheet abuts against the alignment member  32  in a state where the holding-down guide  61   a  holds down the sheet. The guide member  61  is configured as described above, and hence, at the time of aligning the side edge of the sheet, the sheet can be held down in the width direction of the sheet, regardless of the sheet size. 
     In this embodiment, the holding-down guide  61   a  is configured to strike against the alignment member  32 . However, the present invention is not limited to this. For example, as illustrated in  FIGS. 10A and 10B , a regulating member  35  may be provided on a frame (not shown) on an opposite side of the alignment member  32  to the shift rollers  30  in the width direction. Here, the sheet abuts against one surface of the alignment member  32 . Specifically, the alignment member  32  and the regulating member  35  are not formed as the same member, but the regulating member  35  may be provided as a separate member from the alignment member  32 , so that the holding-down guide  61   a  may strike against the regulating member  35  other than the alignment member  32 . With such a configuration, after the holding-down guide  61   a  abuts against the regulating member  35 , the holding-down guide  61   a  is maintained at a position of abutting against the regulating member  35 , and only the guide holder  61   b  slides against the force of the spring  61   c . In such a way, until the sheet strikes against the alignment member  32 , the guide holder  61   b  slides while holding down the sheet. Further, the regulating member  35  may not be disposed at the above-mentioned position. The regulating member  35  may be disposed at a position where the holding-down guide  61   a  abuts against the regulating member  35  when the holding-down guide  61   a  is moved by a predetermined distance toward the alignment member  32 . 
     Note that, when the alignment of the sheet is completed, the shift rollers  30  are first moved to the retreat position RP, and next, the arm  33  is moved in a direction away from the alignment member  32 , which is reverse to the width direction Y, to thereby move the shift rollers  30  to an initial position located at a center of the processing tray  14 . When the next sheet is delivered onto the processing tray  14 , the shift rollers  30  repeat a similar alignment operation. 
     Next, the gripper/stapler portion  13  will be described.  FIGS. 4A and 4B  are schematic views illustrating operation states where a gripper unit  40  nips a sheet bundle SA, and  FIG. 5  is a plan view illustrating a configuration of the gripper/stapler portion  13 . As illustrated in  FIG. 5 , the gripper/stapler portion  13  includes the gripper unit  40  that grips and moves the sheet bundle aligned on the processing tray  14 . The gripper/stapler portion  13  further includes a stapler unit  41  that binds the sheet bundle SA moved to a staple process position by the gripper unit  40 . 
     The gripper unit  40  includes three pairs of grip arms  44  configured to grip the sheet bundle SA aligned on the processing tray  14 . As illustrated in  FIGS. 4A and 4B , each pair of the grip arms  44  includes a fixed grip arm  44   a  configured to support a lower surface of the sheet bundle SA, and a movable grip arm  44   b  that is provided opposite to and above the fixed grip arm  44   a , and presses an upper surface of the sheet bundle SA. Further, the gripper unit  40  is configured to be freely movable in a direction (parallel to the transport direction X of sheets) indicated by an arrow “a” in  FIG. 5 , to thereby nip the sheet bundle SA by the grip arm pairs  44  and move the sheet bundle SA to the staple position. Note that, in the gripper unit  40  of this embodiment, as illustrated in  FIG. 5 , the three pairs of grip arms  44  are provided, and the three pairs of grip arms  44  are arranged at positions spaced apart from one another at a predetermined interval in the width direction Y. 
     The stapler unit  41  incorporates a staple head and an anvil block therein. The stapler unit  41  bends a needle-like staple into a shape of a square bracket, presses the bent staple into the sheet bundle SA, and bends tip ends of the bent staple by the anvil block, to thereby bind the sheet bundle SA. In this embodiment, the stapler unit  41  having the following general configuration is employed. That is, the staple head is attached to one of upper and lower lever members (not shown) of which proximal ends are pivotally supported with respect to each other, and the anvil block is attached to the other of the upper and lower lever members. Then, the upper and lower lever members are moved reciprocally by a drive cam member (not shown) between a separate position and a pressure contact position. 
     As illustrated in  FIG. 5 , on a base  42  on a bottom portion of the processing apparatus C, a guide rail  43  for moving the stapler unit  41  in a direction (parallel to the width direction Y) indicated by an arrow “b” in  FIG. 5  is provided. This guide rail  43  is formed longer than a width of the maximum sheet so as to bind both end portions of the sheets. 
     With the configuration described above, after the sheet bundle SA aligned on the processing tray  14  is gripped by the grip arm pairs  44  of the gripper unit  40 , the gripper unit  40  is moved in the direction (reverse to the transport direction X) indicated by the arrow “a”, to move the sheet bundle SA to the staple position. Note that, at this time, the stopper member  31  as already described with reference to  FIG. 3  has been moved to the retreat position in which the stopper member cannot hamper the movement of the sheet bundle SA by the gripper unit  40 . Then, when the sheet bundle SA has been moved to the staple position by the gripper unit  40 , an end portion of the sheet bundle SA is subjected to a binding process by the stapler unit  41 . 
     Note that, available examples of the binding process include an end binding process for implementing the binding process for one side of the sheet bundle SA, and a two-spot binding process for implementing the binding process for predetermined two spots of the sheet bundle SA. The stapler unit  41  is moved in the direction indicated by the arrow “b” along the guide rail  43 , and executes any one binding process of the end binding process and the two-spot binding process. 
     The sheet bundle SA subjected to the binding process is gripped by the grip arm pairs  44  of the gripper unit  40  one more time. Then, in a state of gripping the sheet bundle SA by the grip arm pairs  44 , the gripper unit  40  is moved in the direction (transport direction X) indicated by the arrow “a”, that is, toward the containing portion  10 . In such a way, the sheet bundle SA is moved so as to be thrust out to the containing portion  10 . After moving the sheet bundle SA to the containing portion  10 , the gripper unit  40  releases the grip for the sheet bundle SA by the grip arm pairs  44 , moves the grip arm pairs  44  to an intermediate position between the stopper member  31  and the staple position, and stands-by for a process for the next sheet bundle. 
     Next, the containing portion  10  will be described based on  FIG. 3 . In the containing portion  10  located on the downstream side of the processing tray  14  in the transport direction X, the multiple stack trays  50  and  51  are arranged. Note that, in this embodiment, the containing portion  10  includes the first stack tray  50  and the second stack tray  51 , and the first stack tray  50  and the second stack tray  51  are selectively connected to the processing tray  14 . Then, as illustrated in  FIG. 3 , a sheet holding-down claw  34  is provided in the processing tray  14 . The sheet holding-down claw  34  holds down the sheets stacked on the sheet placing surface  50   a  or  51   a  of the stack tray  50  or  51 . 
     As described above, in this embodiment, the guide member  61 , which guides each of the sheets at the time of being lifted, and suppresses the curling of the sheet at the time of being lowered, is provided to be slidable in the width direction Y. Then, the guide member  61  is moved in the width direction Y integrally with the shift rollers  30 , and hence even in the case where the holding-down guide  61   a  abuts against the alignment member  32  prior to the sheet, the guide holder  61   b  is moved while being slid integrally with the sheet. In such a way, the sheet can be allowed to abut against the alignment member  32 . As a result, regardless of the sheet size, the buckling of the sheet in the width direction can be suppressed when the positions of the sheets in the width direction Y is aligned. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Applications NO. 2009-212458, filed Sep. 14, 2009, and No. 2010-161371, filed Jul. 16, 2010 which are hereby incorporated by reference herein in their entirety.