Abstract:
There is disclosed a sheet post-processing device which can staple a corner of a sheet bunch conveyed from an image forming device and makes a transverse width of a housing smaller or compact. By disposing a stapler in one end on a sheet processing tray inside a sheet conveying port, the transverse width of the housing is made smaller. For this purpose, the sheet post-processing stores sheets conveyed from the image forming device, matches the sheet bunch stored staples the matched sheet bunch and transfers the matched sheet bunch toward the other end of the sheet bunch and subsequently transfers the stapled sheet bunch toward one end of the sheet bunch.

Description:
BACKGROUND OF THE INVENTION 
     (i) Field of the Invention 
     The present invention relates to a sheet post-processing device which matches a plurality of piled sheets with images formed thereon conveyed from a copying machine, a facsimile machine, a printer or another image forming device to staple the plurality of sheets. 
     (ii) Description of the Related Art 
     Sheets with images formed thereon by the image forming device are continuously piled onto a sheet processing tray (hereinafter referred to as the processing tray) of a sheet processing device (hereinafter referred to as the post-processing device). A bunch of a predetermined number of sheets piled on the processing tray are matched, then stapled, and sent toward a sheet accumulating tray (hereinafter referred to as the accumulating tray) which is adjacent to the post-processing device. 
     In the post-processing device, in order to staple at least one predetermined portion of the sheet bunch on the processing tray, stapling can be performed while moving a stapling device (hereinafter referred to as the stapler) transversely across the processing tray over a side face of the sheet bunch. However, when the stapler is moved in a position above a surface of the processing tray and along a sheet conveying port from the image forming device, a cost of mechanical components for the purpose is raised, and it is difficult to secure an arrangement space of the mechanical components. 
     To solve the problem, in a conventional art, a processing device is used in which when a sheet bunch is stapled, predetermined portions of the sheet bunch are stapled by moving the sheet bunch instead of moving the stapler. The sheet bunch stapled on the processing tray is transferred toward the accumulating tray adjacent to the processing device in a direction orthogonal to a direction in which sheets are conveyed from the image forming device. Therefore, if the sheet bunch is stapled while being transferred, the stapler does not need to be moved. 
     For this reason, in the conventional processing device, the stapler is fixedly disposed in one end of the processing tray to which the sheet bunch is sent, while a sheet holding means (referred to as the holding means) serving as a sheet transfer means for transferring the sheet bunch is disposed in the other end of the processing tray, so that when the sheet bunch is transferred to the stapler by the holding means, the predetermined portion of the sheet bunch is stapled by the stapler. 
     In this case, the stapler requires to staple a portion closely adjacent to the end of the sheet bunch in a sheet-bunch transfer direction. Therefore, as aforementioned, the stapler needs to be disposed in one end of the processing tray in the sheet-bunch conveying direction and close to the sheet-bunch end in the sheet-bunch transfer direction. Furthermore, the holding means needs to be disposed in the other end of the processing tray and outside the sheet conveying port from the image forming device. 
     For this end, a transverse width of a processing-device housing is determined by considering at least a width (determined by a maximum width of the sheet to be processed) of the sheet discharge port disposed on the processing tray, a size of the stapler disposed in one end on the processing tray and a size of the holding means disposed in the other end on the processing tray. As a result, the transverse width of the processing device should be large-sized. 
     SUMMARY OF THE INVENTION 
     Wherefore, an object of the invention is to provide a sheet post-processing device in which a stapler disposed in one end on a processing tray is disposed inside a sheet conveying port to reduce a transverse width of a sheet post-processing device housing. 
     To attain this and other objects, the invention provides a sheet post-processing device which comprises storage means for storing sheets conveyed from an image forming device, matching means for regulating at least one end of a sheet bunch stored in the storage means to match the sheets stored in the storage means, stapling means for stapling the sheet bunch matched by the matching means and transfer means for once transferring the sheet bunch matched by the matching means toward the other end of the sheet bunch and transferring the sheet bunch stapled by the stapling means toward the one end. 
     Here, when the transfer means once transfers the sheet bunch matched by the matching means toward the other end of the sheet bunch, a binding position of the sheet bunch which is between the matching means and a stapling position of the stapling means in a position where the sheet bunch is matched by the matching means is moved toward the stapling position. 
     Additionally, after the transfer means transfers the sheet bunch toward the other end and the stapling means staples the binding position of the sheet bunch between the matching means and the stapling position of the stapling means, the stapling means can staple one portion or plural portions of the sheet bunch while the sheet bunch is transferred toward the one end. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a front appearance of a sheet processing device according to the invention. 
         FIG. 2  is a perspective view showing a rear appearance of the sheet processing device. 
         FIG. 3  is a partially broken perspective view showing the appearance of the sheet processing device. 
         FIG. 4  is a partially broken side view of a post-processing device unit. 
         FIG. 5  is a side view showing an inner structure of an accumulation processing device unit. 
         FIG. 6  is a front view showing an inner structure of the accumulation processing device unit. 
         FIG. 7  is a front view showing an appearance of the accumulation processing device. 
         FIG. 8  is a rear view showing a structure of a shutter  15 . 
         FIG. 9  is a side view showing a mechanism of the shutter  15 . 
         FIG. 10  is a sectional plan view of a sheet processing device. 
         FIG. 11  is a schematic front view of the sheet processing device. 
         FIG. 12  is an enlarged sectional side view showing a main portion of a second holding means in an initial condition in the sheet processing device. 
         FIG. 13  is an enlarged sectional side view showing a main portion of the second holding means dropping a sheet bunch in the sheet processing device. 
         FIG. 14  is a perspective view of an auxiliary tray in the sheet processing device. 
         FIG. 15  is an explanatory view showing an operation of the auxiliary tray in the sheet processing device. 
         FIG. 16  is an enlarged front view showing a reference plate in the sheet processing device. 
         FIG. 17  is a block diagram of a control system in the sheet processing device. 
         FIG. 18  is a first-half flowchart showing post-processing processes of the sheet processing device. 
         FIG. 19  is a latter-half flowchart showing the post-processing processes of the sheet processing device. 
         FIG. 20  is a timing chart showing the post-processing processes of the sheet processing device. 
         FIGS. 21A to 21C  are explanatory views showing post-processing processes for stapling and transferring a sheet bunch from a processing tray to an accumulating tray in the sheet processing device in time series. 
         FIGS. 22A to 22C  are explanatory views showing a modification of  FIG. 21  in which plural portions can be stapled. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of a sheet discharge opening shielding device in a sheet accumulation processing device (hereinafter referred to the accumulation processing device) according to the invention will be described with reference to the drawings. Specifically, a sheet post-processing device (hereinafter referred to as the post-processing device) for stapling or processing otherwise a plurality of sheets discharged from an image forming device to a sheet processing tray and the entire accumulation processing device for receiving a processed sheet bunch to discharge and accumulate the sheet bunch onto a predetermined sheet discharge tray (hereinafter referred to as the accumulating tray) will be described. 
     In  FIGS. 1 to 3 , a sheet processing device  1  is provided with a post-processing device unit  20  and an accumulation processing device unit  50 , each unit being constituted of an independent housing. 
     The post-processing device unit  20  is provided with, as shown in  FIG. 3 , a preparatory conveying means  5  for sorting sheets S with images formed thereon successively discharged from a copying machine  2  to an accumulating tray  3  if a post-processing is unnecessary and to a processing tray  4  if the post-processing is necessary; a matching means  6  for matching the plural sheets S received on the processing tray  4 ; a first holding means  7  for holding and conveying a matched sheet bunch S′; a stapler  8  for stapling the sheet bunch S′ held by the first holding means  7 ; and, as shown in  FIG. 4 , an auxiliary tray  13  positioned above the processing tray  4  and below the preparatory conveying means  5 . 
     Furthermore, as shown in  FIG. 3 , the post-processing device unit  20  is provided with a vertical wall  20   a  functioning as a storing reference surface of the sheets S relative to the processing tray  4 ; an opening  20   b  via which the sheets S are discharged; rail grooves  20   c  and  20   d  for allowing matching members  30  and holding members  34  described later to move; a rail groove  20   e  for allowing the first holding means  7  to move; and an opening  20   f  ( FIG. 1 ) for allowing the sheet bunch S′ held by the first holding means  7  and stapled to move from the processing tray  4  to two accumulating trays  9 A and  9 B. 
     Additionally, as shown in  FIG. 1 , the opening  20   f  is in parallel with the processing tray  4  and with the accumulating trays  9 A and  9 B. Therefore, the sheet bunch S′ moves in parallel from the processing tray  4  to the accumulating trays  9 A and  9 B. Thereby, the alignment of the sheet bunch S′ accumulated to the accumulating tray  9 A or  9 B is effectively maintained. 
     The accumulation processing device unit  50  is provided with, as shown in  FIG. 3 , the accumulating trays  9 A and  9 B which can be raised/lowered to accumulate thereon the sheet bunch S′ stapled by the stapler  8 ; a second holding means  10  for receiving and holding the sheet bunch S′ held by the first holding means  7  and conveyed to the accumulating tray  9 A or  9 B and conveying the sheet bunch S′ to a predetermined position on the accumulating tray  9 A or  9 B; as shown in  FIGS. 5 and 6 , a sheet height detecting means (sheet surface detecting sensor)  11  for detecting the height of the sheet bunch S′ accumulated on the accumulating tray  9 A or  9 B; a halfway taking sensor  14  for detecting that an operator removes the whole or a part of the sheet bunch while the sheet bunch is being accumulated on the accumulating tray  9 A or  9 B; an elevating means  12  for raising/lowering the accumulating trays  9 A and  9 B; and, as shown in  FIGS. 7 to 9 , a shutter  15  for operating when the accumulating trays  9 A and  9 B are raised/lowered. 
     The accumulation processing device unit  50  is also, as shown in  FIG. 1 , provided with a positioning and matching vertical wall  50   a  onto which one side of the sheet bunch S′ conveyed to the accumulating tray  9 A or  9 B abuts; a horizontal opening  50   b  for allowing the second holding means  10  to move in a horizontal direction; and a vertical opening  50   c  interconnected to the horizontal opening  50   b  for allowing the second holding means  10  to rotate in a vertical direction. 
     The accumulating tray  3  is, as shown in  FIG. 3 , formed by tilting an outer-frame upper portion of the post-processing device unit  20 , and has its upstream side positioned below and its downstream side positioned above. Furthermore, a vertical wall  3   a  is extended from an upstream-side end of the accumulating tray  3 , and a releasing opening  3   b  is formed in an upper portion of the vertical wall  3   a.    
     As shown in  FIG. 4 , in the preparatory conveying means  5 , a conveying port  21  is formed in one or rear side face of the post-processing device unit  20 , and aligned with a discharge port (not shown) of the copying machine  2 . On the downstream side of the conveying port  12  a pair of conveying rollers  22  are arranged and a flapper  23 A is then provided for switching a conveying path of the sheets S between a path  24 A on the side of the upper accumulating tray  3  and a path  24 B on the side of the lower processing tray  4 . Moreover, the conveying path  24 A is provided with pairs of conveying rollers  25 A and  25 B, while the conveying path  24 B is provided with a pair of discharge rollers  26 A and  26 B and a sensor  17 . Additionally, in order to reverse the sheets and discharge the reversed sheets to the processing tray  4 , a reversing path  24 C is interposed between the conveying paths  24 A and  24 B. When a rear end of the sheet passes along a reversing flapper  23 B disposed in the conveying path  24 A, the pairs of conveying rollers  25 A and  25 B rotate in reverse, a conveying direction of the sheet is reversed, and the sheet is supplied to the reversing path  24 C. Additionally, a sensor  23 C is attached to the reversing flapper  23 B. 
     The processing tray  4  is positioned below the accumulating tray  3  and tilted in parallel with the accumulating tray  3 . A series of sheets S is successively conveyed via the pair of conveying rollers  22  and the pair of discharge rollers  26 A and  26 B on a terminal end of the path  24 B in a discharge direction A toward the processing tray  4 , so that the sheets S are stapled by the stapler  8 . As shown in  FIG. 3 , a tilted lower end portion of the processing tray  4  is raised or formed in a direction orthogonal to a tray surface, and an inner face of the raised portion forms the vertical wall  20   a  which abuts on one side of the sheet S extended back and forth in a direction orthogonal to the discharge direction A. 
     In the matching means  6 , in order to align the bunch S′ of plural sheets stored on the processing tray  4 , matching is performed before and after the discharge direction by bringing the sheets in contact with the reference surface  4   a  of the processing tray  4  as shown in  FIG. 4 . As shown in  FIG. 10 , on right and left sides of the discharge direction matching is performed by the matching members  30  arranged on opposite sides of the processing tray  4  and shutter type reference plates  31  which can be raised/lowered. 
     In a mechanism for moving the matching members  30 , a rail  32  is extended in a transverse direction below the processing tray  4 , holding members  34  are disposed for supporting the matching members  30  in such a manner that the matching members  30  can run inside the rail  32  via conical rollers  33 , a belt  36  is extended between a pair of pulleys  35 A and  35 B, and the holding members  34  are partially fixed halfway to the belt  36 . Additionally, one pulley  35 B is operated by a matching motor  37  (refer to  FIG. 17 ) to move the matching members  30 . 
     While the sheets S are successively conveyed in the discharge direction A in this manner, the matching members  30  are in retreated and opened positions. After receiving the predetermined number of sheets S, the matching members  30  are advanced and pressed onto the reference plates  31  to perform matching. 
     As shown in  FIG. 16 , the reference plate  31  is provided with a fixed plate  311  fixed to an inner wall of the post-processing device unit  20 ; a shutter solenoid  312  held by the fixed plate  311 , an interconnection plate  313  provided on a tip end of the shutter solenoid  312 ; a pair of arms  314  having one ends interconnected to the interconnection plate  313 ; and shutter plates  318  interconnected to the other ends of the arms  314  via interconnection pins  316  and  317  for converting rotational movement of the arms  314  to linear movement via guide grooves  315  formed in the fixed plate  311 . Additionally, in the process of conveying one sheet bunch S′ from the processing tray  4  to the accumulating tray  9 A or  9 B, when a sheet S forming a base of the next sheet bunch S′ is discharged onto the processing tray  4 , in order to match the base sheet S, the shutter solenoid  312  rotates the arms  314  in such a manner that the shutter plates  318  abut on a top surface of the sheet bunch S′ being conveyed. 
     The first holding means  7  holds a rear-end portion of the sheet bunch S′ matched on the processing tray  4  from above and below to convey the sheet bunch S′ in a conveying direction B orthogonal to the discharge direction A. Furthermore, in the first holding means  7 , as shown in  FIG. 11 , a moving frame  40  is provided with upper and lower holding levers  41  which are opened/closed. A detailed mechanism is not shown, but when a bunch pressing solenoid  43  operates, one side of the sheet bunch S′ is held by the holding levers  41 . Moreover, the holding levers  41  are advanced/retreated by a holding lever motor  42  of  FIG. 17 . 
     Above the processing tray  4  the auxiliary tray  13  formed in a flat plate as shown in  FIGS. 4 and 14  is disposed between the processing tray  4  and the pair of discharge rollers  26 A and  26 B which are rotated by a conveying motor  19 . The auxiliary tray  13  is shorter and narrower than the processing tray  4 , and disposed in a reference position of the processing tray  4  in such a manner that the auxiliary tray  13  can advance/retreat. Specifically, opposite end portions of the auxiliary tray  13  are slidably supported by upper and lower guide rollers  45 , a pinion gear  47  is engaged with a rack  46  in a middle portion, and the auxiliary tray  13  is slid by the pinion gear  47  operatively interconnected to an auxiliary tray motor  48 . Additionally,  FIGS. 4 and 14  show that the auxiliary tray  13  is moved forward. 
     When a series of sheet bunches S′ is discharged onto the processing tray  4  and the sheet bunch S′ is matched, the auxiliary tray  13  is moved forward before the next series of sheets S is conveyed. By receiving the next sheets S, the auxiliary tray  13  separates the sheets S from the sheet bunch S′ being conveyed (being stapled). 
     As shown in  FIG. 15 , the auxiliary tray  13  also has a returning function of conveying the sheet S in a returning direction C opposite to the discharge direction A when the sheet S is laid on the auxiliary tray  13 . The returning function is performed by the discharge roller  26 A and the discharge roller  26 B which elastically abuts on the discharge roller  26 A. Additionally, the diameter of the discharge roller  26 B is larger than that of the discharge roller  26 A, and the discharge roller  26 B is formed of a soft material. When the outer peripheral face of the discharge roller  26 B lightly abuts on the sheet S on the auxiliary tray  13 , the tip end of the sheet S is forwarded in the returning direction C to abut on the contact plate  20   a.    
     Furthermore, since the auxiliary tray  13  is loaded only with about one or two sheets S, a mechanism which is adapted to changes in thickness of the sheet S is unnecessary. Moreover, a timing of advancing/retreating the auxiliary tray  13  is set based on a detection result of the sensor  17  of  FIG. 4  disposed on the upstream side of the discharge direction of the sheet S discharged by the discharge means or rollers  26 A and  26 B for detecting that the tip end of the sheet discharged by the discharge rollers  26 A and  26 B reaches the processing tray  4  or a position above the previous sheet S accumulated on the processing tray  4 . 
     Specifically, as shown in  FIG. 3 , the plural rail grooves  20   c ,  20   d  and  20   e  in the processing tray  4  are extended in a direction orthogonal to the conveying direction of the sheet S. Therefore, in the case where no sheet S is accumulated on the processing tray  4 , if the first sheet S is directly discharged on the processing tray  4 , the tip end of the sheet S is buckled or caught in the rail groove  20   c ,  20   d  or  20   e  in accordance with the height of the processing tray  4 , or another problem occurs. Additionally, even when the sheets S are accumulated on the processing tray  4 , the tip end of the next sheet S abuts on the previous sheet S and is buckled. Furthermore, the aforementioned sheet bunch S′ needs to be separated from the next sheet S. 
     To solve the aforementioned problem, by detecting the tip end of the sheet S by the detecting sensor  17 , the auxiliary tray  13  is advanced, while by detecting the rear end of the sheet S by the detecting sensor  17 , the auxiliary tray  13  is retreated. 
     In this case, it can be assumed that plural sheet sizes are mixed in one sheet bunch S′. For this, based on the sheet size information transmitted from the copying machine  2  and the sheet detection result of the detecting sensor  17 , the retreating timing of the auxiliary tray  13  by means of the auxiliary tray motor  48  is set earlier as the sheet size is larger according to the sheet size information transmitted from the copying machine  2 . Thereby, the sheet is prevented from being buckled in accordance with the sheet size. Additionally, even if sheet sizes are not mixed, the retreating timing may be set earlier when the sheet size is larger than an optional sheet size (e.g., A4 sideways) as a reference. 
     When the sheet bunch S′ on the lower processing tray  4  is conveyed to the accumulating tray  9 A or  9 B, the auxiliary tray  13  is retracted substantially simultaneously with completion of conveyance to the accumulating tray  9 A or  9 B, thereby dropping the sheet S on the auxiliary tray  13  down to the processing tray  4 . 
     As shown in  FIG. 14 , when a relatively large-sized sheet S is conveyed to the processing tray  4 , the sheet S on the auxiliary tray  13  is supported in such a manner that the sheet S hangs from the auxiliary tray  13  onto the processing tray  4 . Additionally, when a small-sized sheet S is conveyed, the sheet S can be received only by the auxiliary tray  13 . 
     The stapler  8  staples the vicinity of edges of the sheet bunch S′ with staples (stapling needles), and is disposed in the vicinity of the front end portion of the vertical wall  20   a  of the processing tray  4  on the side of the accumulation processing device unit  50 . 
     Stapling positions and the number of portions of the sheet bunch S′ to be stapled by the stapler  8  are reached by conveying the sheet bunch with the first and second holding means  7  and  10 . Specifically, when one portion of the sheet bunch is stapled, the sheet bunch is held and conveyed by the first holding means  7 , stopped when the portion is aligned with the stapler  8  and stapled. When two portions are stapled, the sheet bunch is held and conveyed by the first holding means  7 , and the first portion is aligned with the stapler  8  and stapled. Subsequently, after the second holding means  10  in turn holds the sheet bunch, the second portion is aligned with the stapler  8  and stapled. Additionally, by providing the stapler  8  movably along the discharge direction A, portions to be stapled by the stapler may be variable. 
     The accumulating trays  9 A and  9 B are deviated ahead of the processing tray  4  or in a direction orthogonal to the discharge direction A and arranged in parallel with each other, and recesses  9 C and  9 D for taking the trays are formed in top-surface side edges of the accumulating trays. The accumulating trays  9 A and  9 B are also provided with sheet presence detecting sensors  9 E and  9 F. 
     As shown in  FIGS. 5 and 6 , the accumulating trays  9 A and  9 B are arranged in such a manner that the trays are raised/lowered along side walls  50 L and  50 R of the accumulation processing device unit  50 , and the vertical wall  50   a  of the accumulation processing device unit  50  is an accumulation reference plane. The accumulation reference plane is set at a distance d (refer to  FIG. 10 ) in the discharge direction A from the vertical wall  4   a  of the processing tray  4 . 
     Opposite transverse ends of the accumulating tray  9 A or  9 B are fixedly supported by the side walls  50 L and  50 R of a U-shaped elevating frame  52 , and opposite rollers  53  of the elevating frame  52  are vertically movably guided along vertical grooves  54  formed in the side walls  50 L and  50 R. 
     Furthermore, upper and lower frames  62  and  63  on the rear side of the accumulation processing device unit  50  are provided with pulleys  55  and  56 , a belt  57  is extended between the upper and lower pulleys  55  and  56 , and a follower gear  58  fixed to a rotation shaft of the pulley  55  is engaged with a drive gear  59  of an accumulating tray motor  60  to rotate and operate the upper pulley  55 . The elevating frame  52  is fixed halfway to the belt  57  with a fixture  52   a , and vertically moved as the belt  57  runs. 
     A spring  65  is also attached between the elevating frame  52  and the upper frame  62 , an upward carrying force is obtained from a biasing force of the spring  65 , and an alleviating mechanism is constituted in which the weight of the sheet bunch S′ on the processing tray  4  is prevented from excessively acting on the accumulating tray motor  60 . 
     The elevating frame  52  is provided with a transmission type upper tray position detecting sensor  61  and a lower tray position detecting sensor  64 , so that the positions of the accumulating trays  9 A and  9 B can be detected dependent on whether or not light is interrupted by a shielding plate  66  attached to the side wall  50 R. 
     As shown in  FIGS. 12 and 13 , the sheet held by the first holding means  7  is conveyed and pushed from the processing tray  4  onto the accumulating tray  9 A or  9 B via the second holding means  10 . The second holding means  10  also has upper and lower holding levers  71  and  72  for pressing with planes and holding top and under surfaces of the sheet bunch S′. The sheet bunch S′ is held/released by an opening/closing mechanism, and the held sheet bunch S′ is conveyed by a conveying mechanism in the conveying direction B orthogonal to the discharge direction A. Furthermore, a portion of the sheet bunch S′ held in an inclined condition is swung horizontally by a swinging mechanism, and simultaneously moved slightly toward the accumulating tray  9 A or  9 B. 
     First, a proximal end of the upper holding lever  71  is rotatably supported by a first shaft  74  relative to a swinging frame  73 , and the lower holding lever  72  is rotatably supported via a second shaft  75  by the swinging frame  73 . A first arm  76  is supported by the first shaft  74  and rotated integrally with a partial gear  77 , and a tip end pin  76   a  of the first arm  76  is engaged in a groove  71   a  in the upper holding lever  71  and operated to open/close. Similarly, a second arm  78  is supported by the second shaft  75 , and a tip end pin  78   a  of the second arm  78  is engaged in a groove  72   a  in the lower holding lever  72  and operated to open/close. Additionally, a gear portion  79  is attached to a pivotal portion of the second arm  78 , and engaged with the partial gear  77  of the first arm  76  to rotate the upper and lower holding levers  71  and  72  when the arms  76  and  78  are linked and rotated. 
     A pinion gear  80  supported by the swinging frame  73  is engaged with another portion of the partial gear  77 , and a drive gear  82  of an opening/closing motor  83  with the swinging frame  73  attached thereto is engaged with an intermediate gear  81  rotated integrally with the pinion gear  80  to constitute an opening/closing drive mechanism. Additionally, for the opened/closed condition of the upper and lower holding levers  71  and  72 , an operation piece  84  rotated integrally with the upper holding lever  71  is detected by a sensor (not shown). 
     When the second holding means  10  is opened/closed, the upper and lower holding levers  71  and  72  are different from each other in open angle because the diameter of the partial gear  77  of the upper holding lever  71  is large and the diameter of the gear portion  79  of the lower holding lever  72  is small. The upper holding lever  71  is opened by about 30-, while the lower holding lever  72  is opened downward by about 90- (refer to  FIG. 13 ). 
     A lower end of the swinging frame  73  is swingably supported via a swinging shaft  85  by a moving frame  87 . A rotary gear  89  is supported via a shaft  88  parallel with the swinging shaft  85  by the moving frame  87 . An eccentric portion of the rotary gear  89  and a rear portion of the swinging frame  73  above the swinging shaft  85  are interconnected by a linkage  90 . When the rotary gear  89  is rotated, the swinging frame  73  is swung via the linkage  90  to a retreated position of  FIG. 12  or a protruded position of  FIG. 13 . 
     An outer peripheral gear portion of the rotary gear  89  is engaged with a pinion gear  91  supported in a direction orthogonal to the swinging shaft  85  by the moving frame  87 , and an intermediate gear  92  integral with the pinion gear  91  is engaged with a drive gear  93  of a swinging motor  94  attached to the moving frame  87  to constitute a swinging mechanism. 
     In a conveying mechanism of the moving frame  87 , a running member  95  transversely protruded before and after the moving frame  87  is engaged in a guide groove (not shown) extended back and forth in a guide frame  100  fixed to the device unit  50 , and the moving frame  87  is supported in such a manner that the moving frame can move back and forth (in the conveying direction B). 
     Inside the guide frame  100  front and back pulleys  102  are supported by a pulley shaft  101  (another is not shown) and belts  103  are extended between the opposite pulleys. The moving frame  87  is fixed via a clamp member  104  to portions of the belts  103 , a follower pulley  105  is fixed to an end of the pulley shaft  101 , and a drive belt  106  is extended between the follower pulley  105  and a drive pulley  107  of a drive shaft of a conveying motor  108  attached to an under portion of the guide frame  100 . 
     By rotating the conveying motor  108  forward or reversely, the moving frame  87  is advanced or retreated in the conveying direction B together with the second holding means  10 . An initial position (home position) of the second holding means  10  is a receiving position closer to the processing tray  4 , and the second holding means  10  is moved among the receiving position, an intermediate stop position for stapling the sheets with the stapler  8  and a most advanced release position. The second holding means  10  is opened/closed in the initial and release positions, and swung in the release position. 
     Furthermore, the conveying mechanism and the opening/closing and swinging mechanisms of the second holding means  10  are arranged inside a covering of the accumulation processing device unit  50 , so that movement ranges are covered. The slit-like horizontal opening  50   b  is formed in an upper portion of the covering, and the second holding means  10  holding the sheet bunch S′ moves along the horizontal opening  50   b . Additionally, the swung upper and lower holding levers  71  and  72  are protruded from a release end. 
     As shown in  FIG. 5 , in the sheet height detecting means  11 , a rotating detector  110  having a circular arc-shaped tip end is supported by the fixed frame, and protruded/retracted and rotated via a spring  111  when an actuator  112  is operated. The tip end of the rotating detector  110  can make contact with the top surface of the sheet bunch S′ on the accumulating tray  9 A or  9 B, the top-surface position of the sheet bunch S′ on the processing tray  4  is detected with the rotation quantity, and the rising/lowering of the processing tray  4  is controlled. 
     Operations of the mechanisms are linked and controlled in a control unit. On a control panel the number of sheets, the setting number, the necessity of stapling, the stapling position and the like are set by an operator. Operation of each section is controlled based on the setting. 
     When the accumulating tray  9 A passes the horizontal opening  50   b  and is inclined, the shutter  15  prevents the sheet bunch S′ on the accumulating tray  9 A from being caught by or going into the horizontal opening  50   b . The shutter  15  is provided with a shutter plate  16  for opening/closing the horizontal opening  50   b  and a drive section  18  for raising/lowering the shutter plate  16 . 
     As shown in  FIG. 9 , long holes  16 A are formed in upper and lower portions of opposite sides of the shutter plate  16  and, as shown in  FIG. 8 , the shutter plate  16  is vertically movably supported by pins  16 B attached to the side walls  50 L and  50 R. The shutter plate  16  is also provided with a horizontal opening  16 C and openings  16 D to  16 F. 
     As shown in  FIG. 9 , the opening  16 D is covered with a movable plate  16 J rotatably supported via a shaft  16 H in a long hole  16 G and, as shown in  FIG. 5 , the plate  16 J is pushed out by rotation/operation of the second holding means  10 . 
     Opposite sides of an elevating plate  16 K are liftably supported by guides  16 L in the opening  16 E and, as shown in  FIG. 5 , the elevating plate  16 K is pushed down by the rotation/operation of the second holding means  10 . The elevating plate  16 K is reset by a spring  16 M. Therefore, when the second holding means  10  is not rotated, the movable plate  16 J and the elevating plate  16 K are closed safely. 
     The opening  16 F is a hole via which the rotating detectors  110  and  14 A of the sensors  11  and  14  go in/out. 
     The shutter plate  16  is also provided with a rack  16 N, an opened position detecting lever  16 P and a closed position detecting lever  16 Q. 
     On the other hand, a support frame  18 A is horizontally attached between the side walls  50 L and  50 R, and there are the drive section  18 , a sensor  18 B for detecting the opened position detecting lever  16 P and a sensor  18 C for detecting the closed position detecting lever  16 Q. 
     The drive section  18  is provided with a pulse motor  18 D, a timing pulley  18 E, a timing belt  18 F, a timing pulley  18 G and a pinion  18 H engaged with the rack  16 N. 
     When a copying operation is started, the shutter plate  16  is lowered, and the horizontal opening  16 C is aligned with the horizontal opening  50   b  and opened. When the copying of the set number of sheets is completed, the shutter plate  16  is raised to close the horizontal opening  16 C. 
     In the aforementioned drive system, as shown in  FIG. 17 , in response to input/output signals from a CPU  120  and a memory means  121  such as a ROM, a RAM and the like, a parallel I/O  122  is operated and controlled. 
     Post-processing processes of the sheets S will be described with reference to  FIGS. 18 to 21 . Additionally, in flowcharts of  FIGS. 18 and 19  showing a series of post-processing processes and a timing chart of  FIG. 20 , two sheets S of the same size form a sheet bunch S′. After corners of the sheets are bound with a stapler, the sheet bunch is accumulated. Additionally, in  FIG. 20  numerals affixed to code M represent operation division or operation time. 
     One of the two trays  9 A and  9 B is moved in accordance with conditions of the sheet presence detecting sensors  9 E and  9 F of the accumulating trays  9 A and  9 B and the tray position detecting sensors  61  and  64 . When the image forming device  2  starts its image forming operation, the motor  18 D is driven, and the shutter plate  16  is lowered. When the sensor  18 B detects the opened position detecting lever  16 P, the motor  18 D is stopped. In the condition, the horizontal opening  50   b  is aligned with the horizontal opening  16 C of the shutter plate  16  and, as shown in  FIG. 1 , the opening  50   b  is opened. 
     In the flowchart of  FIG. 18 , when a job is started, it is first judged whether or not the job is completed (S 1 ). Since the job has just started, the sheet discharged from the image forming device  2  (S 3 ) is a first sheet of a bunch (S 3 ), the auxiliary tray  13  is retracted (S 4 ) and the sheet is stored on the processing tray  4 . Since the processing tray  4  is inclined with the reference face  4   a  positioned below, the rear end of the discharged sheet in the discharge direction abuts on the reference face  4   a , so that its side edge is aligned. When the second sheet is discharged (S 3 ) (M 1 : operation of a discharged sheet sensor (not shown) and a conveying motor), the matching member  30  is moved to push the rear side of the sheet S and push its front side against the reference plate  31 , thereby matching the back and forth direction of the sheet bunch S′ (S 5 , M 2 : matching). Additionally, if the sheet S is not the final sheet of the bunch (S 6 ), it is checked whether matching is completed (S 7 ). In this case, since the second sheet is the final sheet, the auxiliary tray  13  is protruded after the second sheet is discharged (S 8 , M 3 ). The next first sheet is held above the second sheet which is being matched on the processing tray  4 . 
       FIG. 21  shows strokes in which the sheet bunch S′ is transferred from the first holding means  7  to the second holding means  10  when the sheet bunch S′ is transferred from the processing tray  4  to, for example, the accumulating tray  9 A (to the left in  FIG. 21 ).  FIGS. 21A to 21C  show conditions in which the conveying of the sheet bunch S′ successively proceeds. 
     When matching is performed, the first holding means  7  moves to a nipping position (shown by a chain line in  FIG. 21 ) (S 15 , M 4 ). Subsequently, the rear side of the matched sheet bunch S′ in the discharge direction toward the accumulating tray is nipped by the first holding means  7  (S 19 , M 5 , shown by a chain line in  FIG. 21A ). 
     Here, in the post-processing device of the invention, as shown in  FIG. 21A , the stapler  8  is disposed inside the matched end of the sheet bunch S′ in the matched position on the side of the transfer direction B. Therefore, when the corner of the sheet bunch S′ is stapled, the sheet bunch S′ needs to be once pulled back only by a predetermined distance in a direction opposite to the conveying direction B. The reference plate  31  is raised (S 20 , M 6 ). Additionally, the sheet bunch S′ is pulled back, a binding position on the corner of the sheet bunch S′ is aligned with the stapling position of the stapler  8  (S 22 , M 7 ,  FIG. 21A ), and the sheet bunch S′ is bound by the stapler  8  (S 23 , M 8 ). Subsequently, the first holding means  7  moves the sheet bunch S′ in the conveying direction B and stops in a receiving position of the second holding means (S 24 , M 9 ,  FIG. 21B ). At this time, the second holding means  10  is stopped in an initial position on the side of the processing tray  4  (shown by solid lines in  FIGS. 10 and 11 ), positioned in a retracted position of  FIG. 12  and waits for the stopping of the first holding means  7 . The second holding means  10  receives and holds one side of the tilted sheet bunch S′ on the side of the reference position in its stopped attitude (S 25 , M 10 ). 
     When the second holding means  10  nips the sheet bunch S′, the reference plate  31  in its raised position is lowered. In the lowered condition, the reference plate  31  lightly presses the sheet bunch S′ to allow the sheet bunch S′ to pass. 
     After nipping is performed by the second holding means  10  as aforementioned, the first holding means  7  is opened (S 26 , M 11 ,  FIG. 21C ) and moves to the initial position (shown by a solid line of  FIG. 10 ) to hold the next sheet bunch S′ (S 27 ), so that the next sheet bunch S′ can be transferred. 
     Subsequently, the second holding means  10  moves to a forward discharge position (shown by chain lines in  FIGS. 10 and 11 ), finishes conveying in the conveying direction B and stops (S 30 , M 13 ). In the discharge position, the second holding means  10  is swung from the retracted or swung position shown in  FIG. 12  to a protruded position shown in  FIG. 13 . The second holding means  10  is placed in its horizontal nipping condition and moved in a direction orthogonal to the conveying direction B (S 31 , M 14 ). Additionally, when the second holding means  10  is swung from the retracted or swung position of  FIG. 12  to the protruded position of  FIG. 13 , the movable plate  16 J is rotated and the elevating plate  16 K is lowered by the second holding means  10 . 
     The end position aligned with the reference position on the processing tray  4  is nipped and conveyed by the second holding means  10  as shown in  FIG. 12 . When the second holding means  10  is swung to the condition shown in  FIG. 13 , the nipped end of the sheet bunch S′ is moved toward the accumulating tray  9 A. The moved position substantially coincides with the reference face  50   a  in the accumulating tray  9 A. The nipped sheet end becomes horizontal while being moved (M 14 ), and the upper and lower holding levers  71  and  72  are operated to open as shown by chain lines (S 32 , M 15 ). Then, the nipped sheet bunch S′ is dropped and discharged downward as it is, and accumulated onto the accumulating tray  9 A. 
     When the second holding means  10  is operated to open, the swinging frame  73  is retracted (S 33 , M 16 ) and the second holding means  10  is moved rearward along the conveying direction B to return to the initial condition (S 34 , M 17 ). At this time, even if the next sheet bunch S′ is conveyed, the upper and lower holding levers  71  and  72  are sufficiently opened. Therefore, the sheet bunch S′ fails to interfere with the upper and lower holding levers  71  and  72 . Subsequently, the levers can be operated to close and nip the next sheet bunch S′ in the initial position. 
     As aforementioned, when the second holding means  10  is swung to the horizontal condition (M 14 ), the actuator (bunch pressing solenoid)  112  is operated, the rotating detector  110  is placed in a sheet-bunch pressing condition (S 35 ), and a sheet height is detected (S 36 ). Subsequently, the operation of the actuator  112  is canceled, and the pressed condition is released (S 37 , M 18 ). When the sheet is higher than the predetermined position, the accumulating tray  9 A is operated by the elevating means  12  to go down to a predetermined level (S 38 , M 19 ). Additionally, when the accumulated sheet bunch S′ is taken out by an operator halfway, the accumulating tray  9 A is raised following the detection of the halfway taking sensor  14 . 
     Since the second holding means  10  is operated to move inside a cover at the time of conveying in the back and forth direction, the second holding means  10  and its conveying mechanism fail to interfere with the operator who is taking the sheet bunch S′ on the accumulating tray  9 A. Additionally, since the nipped sheet bunch S′ is conveyed, the matched condition of the sheet bunch S′ is prevented from being disturbed during the conveying. Here, when the sensor  11  detects that, for example, a predetermined number of or more sheets are stored in the accumulating tray  9 A, the motor  60  shown in  FIG. 5  is operated, the elevating frame  52  is raised, and the lower tray  9 B is moved to stop in a storage position. At this time, since the shutter  15  is closed, the sheet on the accumulating tray  9 A is inhibited from entering the horizontal opening  50   b . Thereafter, the sheet bunch is accumulated onto the accumulating tray  9 B in the same manner. 
     In the embodiment described above, the first and second holding means  7  and  10  are constituted of the holding levers for pressing and holding the sheet bunch in plane configurations, but the sheet bunch may be pressed and held by rollers or the like from above and below. Each conveying mechanism can be varied, and the actuator can be changed into a known mechanism. 
     Furthermore, in the embodiment, the invention is applied to the copying machine  2  as the image forming device, but the invention may be applied to the copying machine  2  in both digital and analog systems. Additionally, it is natural to apply the invention to a printer (including a laser printer), a facsimile machine or other various image forming means (image record devices). 
     Moreover, in the embodiment, the case where one corner is bound has been described. Alternatively, as shown in  FIG. 22 , after the corner is bound ( FIG. 22A ), one portion or plural portions of the sheet bunch S′ may be stapled by operating the stapler  8  while the sheet bunch is moved ( FIG. 22B ). 
     As aforementioned, in the conventional art, the transverse width of the processing-device housing is determined in consideration of at least the width (determined by the maximum width of the sheet to be processed) of the sheet discharge port disposed on the processing tray, the size of the stapler disposed in one end on the processing tray and the size of the holding means disposed in the other end on the processing tray. As a result, the transverse width of the processing device should be large-sized. 
     In the post-processing device of the invention, the conveying means (first holding means) is constituted to be movable in the direction opposite to the conveying direction of the sheet bunch, and the stapler  8  is disposed inside the matched end of the conveying direction in the matched position of the sheet bunch S′. Therefore, the corner of the sheet bunch can be stapled, while the transverse width of the sheet post-processing device housing can be made small-sized.