Patent Publication Number: US-6991421-B2

Title: Sheet accumulation processing device

Description:
The Application is a continuation of and claims priority under 35 U.S.C. §120 to application Ser. No. 09/103,229, filed Jun. 23, 1998 now abandoned entitled SHEET ACCUMULATION PROCESSING DEVICE, which is hereby incorporated by reference in its entirety, and which claims priority under 35 U.S.C. § 119 to Japanese Patent Applications 9-165937, filed Jun. 23, 1997 and 10-102737, filed Apr. 14, 1998 both of which are incorporate by reference in their entirety for all purposes. 

   BACKGROUND OF THE INVENTION 
   (i) Field of the Invention 
   The present invention relates to a sheet accumulation processing device for accumulating and discharging sheets or a sheet bunch continuously fed from a copying machine, a printer or another image forming device onto a predetermined accumulating tray, especially to a shielding device of an opening formed in a device surface for conveying sheets in a transverse direction and piling the sheets on an accumulating tray. 
   (ii) Description of the Related Art 
   In many cases, a rotating roller usually constituted of a drive roller and a free roller engaged with the drive roller to dependently rotate is used in a discharge mechanism for discharging sheets with images formed thereon from a sheet discharge port of an image forming device to a sheet discharge tray. The sheet discharge tray is inclined and attached to the image forming device below, and the sheets discharged one by one are accumulated on the tray while ends of the sheets are aligned with a positioning/matching vertical wall of the image forming device. Furthermore, in an image forming device in which plural sheet discharge trays are provided and sheets can be discharged to an optional sheet discharge tray, when the sheet discharge tray loaded with plural sheets vertically passes the sheet discharge port of the image forming device, the sheets are dropped or narrowed toward the sheet discharge port, thereby disadvantageously jamming the sheets and disturbing matched or superimposed conditions of the sheets, because the sheet discharge device is inclined as aforementioned. To prevent this and other problems, there is provided a shutter device having a drive mechanism for shielding the sheet discharge port at least while the sheet discharge port is vertically moved. 
   Recently, in a sheet accumulation processing device, instead of discharging the sheets with images formed thereon from the image forming device as they are to the sheet discharge tray as aforementioned, after superimposed end faces of the predetermined number of stacked or gathered sheets are matched, stapling, punching or another processing is performed. The processed sheet bunch can be transferred to an adjoining sheet accumulation processing device, and discharged to a predetermined sheet accumulating tray. 
   In order to provide a shielding means having a conventional drive mechanism, for example, a motor as a drive device, a drive force conducting belt, a shutter member operatively interconnected to the belt, a shutter position detector and a control device are required for constituting a shielding device. Therefore, costs of these constituting members and a space for arranging the constituting members in a device housing need to be secured. Additionally, the opening/closing of the shutter member needs to be controlled synchronously when a sheet holding means is protruded/retreated into or out of the housing at a high speed. Therefore, reliability would be deteriorated after a long use. 
   Additionally, even when an opening is provided with some shielding means like in the conventional art, whether intentionally or not, people hands or articles are inserted or entered via the opening into the device while the sheet holding means is inoperative or on standby. In this case, not only device troubles but also safety problems still remain unsolved. 
   SUMMARY OF THE INVENTION 
   Wherefore, an object of the invention is to provide a sheet accumulation processing device which is simple in mechanism, low in cost and requires no complicated control and to provide a safe and reliable shielding mechanism for a sheet discharge opening. 
   To attain this and other objects, the invention provides a sheet accumulation processing device provided with a sheet discharge opening shielding device having the following constitution: 
   An end of a sheet bunch is sent from an adjoining sheet post-processing device via a slit opening formed in a housing front face of the sheet accumulation processing device. The sheet accumulation processing device has a holding means for holding from above and below and receiving the fed sheet bunch. The holding means holds the sheet bunch in a predetermined receiving position in the slit opening before moving the sheet bunch along the opening while holding the sheet bunch. Furthermore, in a predetermined discharge position in the slit opening, the holding means protrudes the sheet bunch to a front of the housing and is protruded from a sheet bunch holding condition toward the front of a housing face. Subsequently, by releasing the sheet bunch, the sheet bunch is piled on the sheet accumulating tray. Here, the sheet discharge opening shielding device is changed from a closed condition to an opened condition accompanying the protruding operation of a sheet holding section. Subsequently, when the sheet holding section is retreated into the slit opening, the shielding device is dependently changed from the opened condition to the closed condition, so that the sheet holding section can be protruded and retreated via the housing front surface. 
   Moreover, the opening shielding device is constituted of a suspension plate suspended from a support of its upper end disposed in an upper portion of the slit opening and an elevating plate liftably disposed in a lower portion of the slit opening. The suspension plate and the elevating plate dependently open or close the opening shielding device when the sheet holding section is rotated or retreated as aforementioned. 
   The elevating plate is usually lifted up by one or plural elastic members toward the suspension plate, and pushed downward to opened accompanying the protruding operation of the sheet holding means. The protruding operation of the sheet holding means includes an operation that the sheet holding means is rotated and protruded forward and downward from the housing surface. 
   Additionally, another sheet accumulation processing device of the invention has a sheet holding means for receiving, holding and transferring a sheet conveyed from one side face of the device toward the other side face and protruding forward and placing the sheet onto an accumulating tray disposed in front of the device, and an opening formed in the device via which the sheet holding means transfers and piles the sheet as aforementioned. The opening is constituted of a horizontal opening formed in a front face of the device for passing the end of the sheet and a vertical opening adjacent to the horizontal opening for the piling operation of the holding means to the font of the device. The horizontal opening is constituted to close when the holding means is on standby and open when the holding means transfers and piles the sheet. A vertical opening means for opening/closing the vertical opening is further provided. The vertical opening means inhibits the vertical opening from opening at least when the holding means is on standby. 
   The vertical opening means is further constituted of an upper rotating shutter means and a lower elevating shutter means. The rotating shutter means is rotatably suspended from its upper end as a support, and the elevating shutter means is lowered to open when the holding means piles the sheets. The rotating shutter means is inhibited from rotating while the horizontal opening is closed, and allowed to rotate toward the front face of the device when the sheet holding means piles the sheets. The horizontal opening is opened when a panel member disposed on the device front face is raised, and closed when the panel member is lowered. The rotating shutter means is inhibited from rotating when the panel member is in a lowered position, and allowed to rotate when the panel member is raised. Furthermore, for safety, the rotating shutter means is locked to be prevented from rotating until the holding means moves to the vertical opening. 
   On the other hand, the elevating shutter means is lifted up or down by the movement of the sheet holding means. Specifically, when the sheet holding means moves from one side face of the device to the other side face and a portion of the sheet holding means operates a lever means disposed on a movement track, the elevating shutter means is raised, and when the sheet holding means returns to its original position, by resetting the operation of the lever means, the elevating shutter means is lowered. 

   
     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 postprocessing processes of the sheet processing device. 
       FIG. 19  is a latter-half flowchart showing the postprocessing processes of the sheet processing device. 
       FIG. 20  is a timing chart showing the postprocessing processes of the sheet processing device. 
       FIGS. 21A to 21C  are explanatory views showing postprocessing processes for transferring a sheet bunch from a processing tray to an accumulating tray in the sheet processing device in time series. 
       FIG. 22  is a rear view showing a structure of a shutter  15 ′ according to a second embodiment. 
       FIG. 23  is a rear view showing the structure of the shutter  15 ′. 
       FIG. 24  is a plan view showing a relationship between regulating members  255  and  266  and a rotating arm  206 . 
       FIG. 25  is a side view showing a mechanism of the shutter  15 ′. 
       FIGS. 26A and 26B  are side views showing a locking and an unlocking in a locking mechanism of the shutter  15 ′. 
       FIG. 27  is an enlarged sectional side view showing a main portion of a swinging mechanism of a second holding means  10 ′ in a retreated condition according to the second embodiment. 
       FIG. 28  is an enlarged sectional side view showing a main portion of the swinging mechanism of the second holding means  10 ′ in an advanced condition according to the second embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   First, the whole of a sheet processing device will be described with reference to the accompanying drawings. The device is constituted of a sheet post-processing device for stapling or processing otherwise plural sheets discharged from an image forming device to a sheet processing tray (hereinafter referred to as the post-processing device) and an accumulation processing device for receiving a processed sheet bunch and discharging and accumulating the sheet bunch to a predetermined sheet discharge tray (hereinafter referred to as the accumulating tray). Embodiments of a shielding mechanism of the invention will also be described in detail. 
   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 postprocessing 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 upstreamside 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  5 OR 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 SOR. 
   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 fame  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 SOR, 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. 
   A post-processing process of the sheets S will be described with reference to  FIGS. 18 to 21 . Additionally, in a flowchart of  FIGS. 18 and 19  showing a series of post-processing processes and a timing chart of  FIG. 20 , after stapling two sheets S (the same size) into a sheet bunch S′, the bunch is accumulated. Furthermore, a numeral affixed to a code M in  FIG. 20  indicates operation division or time in each section. 
   Dependent on 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 , either of the two trays  9 A and  9 B is moved to the discharge port. When an image forming operation of the image forming device  2  is started, the motor  18 D is operated, the shutter plate  16  is lowered, the opened position detecting lever  16 P is detected by the sensor  18 B, then the motor  18 D is stopped. In this 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, in an initial setting, the conveyed number of sheets discharged from the image forming device  2  is set to N=0, and a sheet matching flag is set to F 0 =0 (matching completed) by assuming that previously conveyed sheets are completely matched (S 1 , S 2 ). The sheets S are successively discharged from the image forming device  2  (S 3 ). In this case, the auxiliary tray  13  is protruded, the sheets are conveyed to increase the value of N and a series of plural sheets (two sheets) S are piled (S 4 , S 5 , S 6 ) and the value is set to N=0 for the subsequent conveying (S 7 ). When it is judged that the sheets are completely matched (S 8 ), the auxiliary tray  13  is retracted, and the sheet bunch S′ is dropped and stored onto the processing tray  4  (S 9 , S 10 ), a lower inclined side of the sheet bunch S′ abuts on the reference surface  4   a  as a storage end face and the sheet bunch S′ is aligned in its transverse direction (Ml: operation of a discharge sensor (not shown) and the conveying motor). Subsequently, the matching members  30  are moved to push the rear side of the sheet S and push the front side thereof onto the reference plates  31 , so that the sheet S is matched in its back and forth direction (S 11 , M 2 : matching). During the matching of the sheet S (F 0 =1), the auxiliary tray  13  is protruded when the next series of sheets S is conveyed in (M 3 ), and the sheet S is held to be separated from the sheet being matched/conveyed below (S 11 –S 14 ). 
     FIG. 21  shows a stroke in which the sheet bunch S′ is transferred from the first holding means  7  over to the second holding means  10  while the sheet bunch S′ on the processing tray  4  is conveyed toward, for example, the accumulating tray  9 A (to the left as seen in  FIG. 21 ).  FIGS. 21A to 21C  show that the conveying of the sheet bunch S′ successively progresses, and the second holding means  10  and the stapler  8  are in fixed positions in the movement stroke. 
   When matching is performed, the first holding means  7  moves to an initial position (shown by a solid line of  FIG. 10 ) (S 15 , M 4 ). Moreover, at this time the second holding means  10  is in the initial position (shown by the solid line of  FIG. 10 ) (S 16 ). Here a flag indicating whether or not the sheet bunch S′ is being transferred is set to F 1 =0 (not being transferred) (S 17 ). In the matched condition, the rear side of the sheet bunch S′ is held (nipped) by the first holding means  7  (S 18 , S 19 , M 5 , shown by a chain line in  FIG. 21A ). 
   The reference plates  31  (shutters) are raised (S 20 , M 6 ). When a new sheet bunch S′ is conveyed (F 1 =1, S 21 ), the sheet bunch S′ is allowed to move in the conveying direction B. Subsequently, the first holding means  7  is operated to move forward by a predetermined quantity, the sheet bunch S′ is moved to a first stapling position in a direction of the accumulating tray  9 A intersecting the discharge direction A (S 22 , M 7 , shown by a solid line in  FIG. 21A ) and the first portion is stapled by the stapler  8  (S 23 , M 8 ). Additionally, the reference plates  31  are raised until the sheet bunch S′ is conveyed in, then immediately lowered. In the lowering condition, the sheet bunch S′ is lightly pressed, so that the sheet bunch S′ can pass. 
   Subsequently, the first holding means  7  further moves forward and stops in a second stapling position (S 24 , M 9 ,  FIG. 21B , condition shown by a solid line in  FIG. 3 ). The second holding means  10  is then stopped in the initial position on the side of the processing tray  4  (position shown by a solid line in  FIG. 10  or  11 ), swung to a retreated position of  FIG. 12  until the first holding means  7  stops, and receives and holds the reference-position side of the tilted sheet bunch S′ while being stopped (S 25 , M 10 ). 
   After the second holding means  10  holds the sheet bunch S′ as aforementioned, the first holding means  7  is released (S 26 , M 11 ,  FIG. 21C ), returns to a holding position (shown by the solid line in  FIG. 10 ) to hold the next sheet bunch S′ (S 27 ) and allows the next sheet bunch S′ to be transferred (S 28 ). Subsequently, the second portion is stapled by the stapler (S 29 , M 12 ). In each of the aforementioned stapling positions, the transfer quantity of the first holding means  7  is set based on an operator′s instruction. 
   Subsequently, the second holding means  10  moves forward to a release position (shown by a chain line in  FIG. 10  or  11 ), finishes conveying in the conveying direction B and stops (S 30 , M 13 ). In the release position, the second holding means  10  is moved from the retreated swung position shown in  FIG. 12  to the protruded position shown in  FIG. 13 , brought in a horizontal holding condition and moved in a direction orthogonal to the conveying direction B (S 31 , M 14 ). Additionally, when the second holding means  10  swings from the retreated 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 . 
   An end portion of the sheet bunch S′ aligned with the reference position on the processing tray  4  is held and conveyed by the second holding means  10  as shown in  FIG. 12 . When the second holding means  10  swings to the condition shown in  FIG. 13 , an end of the held sheet bunch S′ is moved toward the accumulating tray  9 A. The moved position is substantially aligned with the reference plane  50   a  in the accumulating tray  9 A. Along with the movement the held sheet end becomes horizontal (M 14 ), the upper and lower holding levers  71  and  72  are released and operated as shown by chain lines (S 32 , M 15 ), and the held sheet bunch S′ is dropped and released downward as it is and piled on the sheet bunch S′ already accumulated on the accumulating tray  9 A. 
   In this case, the sheet bunch S′ is piled up without its end being largely deviated from the end of the accumulated sheet bunch S′ below and without its dropped end being caught in the stapled portion of the sheet bunch S′ below. 
   While the second holding means  10  is opened, the swinging frame  73  is retreated (S 33 , M 16 ). Subsequently, the second holding means  10  is moved backward along the conveying direction B to return to the initial condition (S 34 , M 17 ). In this case, even if the next sheet bunch S′ is forwarded, the upper and lower holding levers  71  and  72  are sufficiently opened and, therefore, the sheet bunch S′ fails to interfere with the upper and lower holding levers  71  and  72 . Subsequently, in the initial position, the levers can be closed to hold the next sheet bunch S′. 
   When the second holding means  10  is swung to the horizontal condition (M 14 ) as aforementioned, the actuator (bunch pressing solenoid)  112  is operated, the rotating detector  110  is placed in the sheet bunch pressing condition (S 35 ), a sheet height is detected (S 36 ), the operation of the actuator  112  is then canceled, and the pressing condition is released (S 37 , M 18 ). When the accumulating tray  9 A is higher than a predetermined position, it is lowered to a predetermined level by the elevating means  12  (S 38 , M 19 ). Additionally, if an operator takes out the accumulated sheet bunch S′ halfway, the accumulating tray  9 A is raised in response to detection of the halfway taking sensor  14 . 
   At the time of conveying the sheet bunch S′ back and forth, since the second holding means  10  is moved/operated inside the covering, the second holding means  10  and its conveying mechanism fail to interfere with the operator who is trying to take the sheet bunch S′ from the accumulating tray  9 A. Moreover, since the held sheet bunch S′ is conveyed, the matched condition of the sheet bunch S′ is not disturbed during conveyance. Here, when it is detected by the sensor  11  that the predetermined number of or more sheets are stored on the accumulating tray  9 A, the motor  60  shown in  FIG. 5  is operated to raise the elevating frame  52  and stopped when the lower tray  9 B moves to its storing position. Additionally, the shutter  15  is closed, and the sheet on the accumulating tray  9 A does not go into the horizontal opening  50   b . Thereafter, sheet bunches are similarly accumulated on the accumulating tray  9 B. 
   Additionally, in the embodiment, the first and second holding means  7  and  10  are constituted of the holding levers for pressing with their planes and holding the sheets, but may be constituted of rollers or other members for pressing and holding the sheets from above and below. The conveying mechanism in each section can be varied, and the actuator can be replaced with 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 device). 
   Another embodiment of a shielding mechanism of the invention will be described. 
     FIG. 22  is a rear view showing a structure of a shutter  15 ′ in a second embodiment of the accumulation processing device unit  50 . In the same manner as the shutter  15  of the first embodiment, a 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. A new shutter plate  16 ′ replacing the shutter plate  16  is raised/lowered by the drive section  18 . Here, the shutter plate  16 ′ is usually lowered to close the horizontal opening  50   b , but when a copying operation is started, the shutter plate  16 ′ is raised by the drive section  18  to open the horizontal opening  50   b , so that the second holding means  10  can move inside the horizontal opening  50   b . Subsequently, the held sheet bunch is discharged to the accumulating tray  9 A or  9 B of the accumulation processing device unit  50  and the second holding means  10  returns to its initial position, the shutter plate  16 ′ is lowered to its original position to close the horizontal opening  50   b , thereby preventing hands or the like from having access into the horizontal opening  50   b . Additionally, since the mechanism of the drive section  18  is the same as aforementioned, the description thereof is omitted. 
   The shutter plate  16 ′ is provided with a new movable plate  16 J′ replacing the shutter plate  16 J shown in  FIG. 5 . The movable plate  16 J′ is pushed out by rotation of the second holding means  10 , and raised/lowered when the shutter plate  16 ′ is raised/lowered. 
   Below the movable plate  16 J′ (also referred to as the rotating shutter), a vertically movable elevating plate  16 K′ (also referred to as the elevating shutter) is disposed. When the shutter plate  16 ′ closes the horizontal opening  50   b  (refer to  FIG. 1 ) as shown in  FIG. 22 , the movable plate  16 J′ and the elevating plate  16 K′ (generically referred to as the vertical opening section) partially intersect each other. 
   An arm follower plate  201 A is fixedly interconnected to the elevating plate  16 K′. The arm follower plate  201 A; an elevating arm  202 , a connecting arm  205  and a rotating arm  206  are interconnected via pins  201 B,  204  and  205 A in such a manner that they are relatively rotated. The arm follower plate  201 A is also engaged with a rail  201 C extended in a direction in which the elevating plate  16 K′ can be raised/lowered, and can move along the rail  201 C. 
   The rotating arm  206  can be rotated about an axis of a pin  207 A relative to a support member  207  fixedly attached to the accumulation processing device unit  50 . The rotating operation of the rotating arm  206  pivotally rotated about the pin  207 A is transmitted via the connecting arm  205  to the elevating arm  202 . Since the elevating arm  202  is halfway supported rotatably via a pin  203 A, the rotation of the rotating arm  206  allows the elevating arm  202  to rotate. Furthermore, the arm follower plate  201 A and the elevating arm  202  are movably interconnected by the pin  201 B in an elongate hole  202 A in which the pin  201  can move. Therefore, when the elevating arm  202  rotates, a drive force is transmitted to the pin  201 B, so that the arm follower plate  201 A vertically moves along the rail  201 C. When the arm follower plate  201 A vertically moves, the elevating plate  16 K′ is raised/lowered. 
     FIG. 22  shows that the elevating plate  16 K′ just closes the horizontal opening  50   b , and the rotating arm  206  is in a substantially horizontal position. On the other hand,  FIG. 23  shows that the rotating arm  206  of  FIG. 22  is rotated or moved to the left as seen in the figure (rotated counterclockwise) and the elevating plate  16 K′ is lowered to open the horizontal opening  50   b.    
   Here, one side of the rotating arm  206  forms a substantially straight contact moving side  206 B. The rotating arm  206 , the connecting arm  205  and the elevating arm  202  are constituted in such a manner that the side  206 B is in a substantially horizontal position when the elevating plate  16 K′ is closed. Moreover, one end of the rotating arm  206  on the side of the pin  207 A has a contact moving side  206 C curved and bent substantially by  90  degrees. On the other hand, the moving frame  87  (refer to  FIG. 12 ) for moving the second holding means  10  toward the horizontal opening  50 b is provided with a regulating member  256  which abuts on the contact moving sides  206 B and  206 C and a regulating member  255  which abuts only on the contact moving side  206 B. When the second holding means  10  moves, the regulating members slide on the contact moving sides  206 B and  206 C or on the contact moving side  206 C. When the second holding means  10  is in its initial position, the regulating member  255  is in a position shown in  FIG. 22  to regulate the counterclockwise rotation of the rotating arm  206  and maintain the contact moving side  206 B substantially horizontally. When the second holding means  10  moves horizontally toward the elevating plate  16 K′ inside the horizontal opening  50   b , the regulating members  255  and  266  slide on the contact moving side  206 B, but still regulate the rotation of the rotating arm  206 . Subsequently, when the second holding means  10  reaches the elevating plate  16 K′, as shown in  FIG. 23 , only the regulating member  256  goes beyond the pin  207 A, abuts on the contact moving side  206 C and rotates the rotating arm  206  counterclockwise. The rotating movement is transmitted to the connecting arm  205  and the elevating arm  202 , the arm follower plate  201 A then moves downward along the rail  201 C, and the elevating plate  16 K′ is lowered. When the second holding means  10  leaves the elevating plate  16 K′ to return to its initial position, the regulating member  256  leaves the contact moving side  206 C and slides on the contact moving side  206 B. To return the contact moving side  206 B to the substantially horizontal position, the elevating plate  16 K′ is raised. 
     FIG. 24  is a top view clarifying the relationship between the regulating members  255  and  256  and the rotating arm  206 . The regulating members  255  and  256  integrally move in a direction in which the rotating arm  206  is extended. When the regulating members  255  and  256  are compared, the regulating member  256  is extended from a conical roller  253  described later longer as compared with the regulating member  255 . In the initial position, as shown in  FIG. 24 , when the regulating member  255  abuts on the contact moving side  206 B partially having a wide area, the rotation of the rotating arm  206  is regulated. On the other hand, for the other end of the contact moving side- 206 B, to avoid the abutment on the regulating member  255 , a side of the contact moving side  206 B opposed to the regulating member  255  is halfway cut thin. In the region, the regulating member  255  does not interfere with the contact moving side  206 B or regulate the rotation of the rotating arm  206 , but the regulating member  256  interferes with the contact moving side  206 B. Therefore, the rotation of the rotating arm  206  is regulated by the regulating member  256 . A configuration of the contact moving side  206 B and a distance between the regulating members  255  and  256  are predetermined in such a manner that while the regulating members  255  and  256  integrally move toward the contact moving side  206 C, the regulation of the rotating arm  206  by the regulating member  255  is replaced by the regulation by the regulating member  256 . The regulating member  256  further moves along the contact moving side  206 B and abuts on the contact moving side  206 C to rotate the rotating arm  206  as aforementioned. 
     FIG. 25  is a partially broken side view of the shutter  15 ′ showing that the movable plate  16 J′ and the elevating plate  16 K′ are slightly opened. Conical rollers  252  and  253  attached to opposite ends of a rod shaft  254  can be rotated about the shaft. Additionally, the shaft  254  and the conical rollers  252  and  253  form a running member  95 ′ of the second embodiment replacing the running member  95  described with reference to  FIG. 13  and the like. The running member  95 ′ is disposed on the moving frame  87  for moving the second holding means  10  in the same manner as the running member  95  of the first embodiment. Rails  250  and  251  for running the conical rollers  252  and  253  are extended vertical to a surface of  FIG. 25  to enable the second holding means  10  to move. By using the shaft  254  coaxially, the other end of one conical roller is provided with the cylindrical regulating member  256  described above. A portion of the outer periphery of the regulating member  256  abuts on the contact moving sides  206 B and  206 C of the rotating arm  206  to control the rotation of the rotating arm  206 . 
   opening/closing of the movable plate  16 J′ will be described with reference to  FIGS. 22 ,  23  and  25 . The shutter plate  16 ′ has opposite plate planes substantially perpendicularly bent in parallel with the side walls  50 L and  50 R in the vicinity of the side walls  50 L and  50 R of the accumulation processing device unit  50 . As shown in  FIG. 25 , long holes  16 A′ are formed vertically in the plate plane, and 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 provided with an opening  16 D′. To open/close the opening  16 D′, the movable plate  16 J′ is rotatably attached to the shutter plate  16 ′ via a pin  16 T. A spring or another elastic member  16 U is also provided between the shutter plate  16 ′ and the movable plate  16 J′, and acts on the movable plate  16 J′ to close the opening  16 D′ by using the shutter plate  16 ′ as a support base. Therefore, the opening  16 D is usually closed by the movable plate  16 J′. 
   Furthermore, a stopper member  16 P branched and extended toward the elevating plate  16 K′ is fixed to the movable plate  16 J′. Here, when the second holding means  10  is in the initial position, the shutter plate  16 ′ is positioned to close the horizontal opening  50   b , while an opposed tip end of the elevating plate  16 K′ is interposed between the movable plate  16 J′ and the extended stopper member  16 P. Therefore, the stopper member  16 P interferes with the elevating plate  16 K′ to regulate the opening of the movable plate  16 J′. 
     FIG. 26A  is a side view taken along a broken line A–A′ of  FIG. 22  schematically showing a relationship between the movable plate  16 J′ and the elevating plate  16 K′. Specifically, when the tip end of the elevating plate  16 K′ enters between the movable plate  16 J′ and the stopper member  16 P, the movable plate  16 J′ is prevented from rotating about the pin  16 T. 
   Even when the movable plate  16 J′ is apart from the elevating plate  16 K′, a mechanism for locking the opening prevents an open end of the movable plate  16 J′ from being lifted up to open from the outside, if the movable plate  16 J′ is being raised and within a predetermined distance. The locking mechanism will be described with reference to  FIG. 26B . 
     FIG. 26B  is a side view taken along a broken line B–B′ of  FIG. 23 . A small piece  16 V is provided in an opening/closing portion of the movable plate  16 J′. A vertical regulating plate  16 W is fixed to the accumulating tray  9 A or  9 B of the accumulation processing device unit  50  for interfering with the small piece  16 V to regulate and inhibit the movable plate  16 J′ from rotating. When the movable plate  16 J′ is operated by the drive motor  18  to move upward, the small piece  16 V moves upward relative to the regulating plate  16 W. Subsequently, when the movable plate  16 J′ moves up by the predetermined distance, the small piece  16 V fails to interfere with the regulating plate  16 W. Therefore, the rotation of the movable plate  16 J′ is not regulated, the inhibition of rotation is removed, and the opening  16 D′ can be opened. Specifically, in order to open the opening  16 D′, the shutter plate  16 ′ needs to move upward by the predetermined distance or more. Therefore, the access from the outside can be restricted, and safety can be enhanced by the locking mechanism. Alternatively, when the upper and lower holding levers  71  and  72  of the second holding means  10  just reach a position before the shutter plate  16 ′, the inhibition may be removed. 
     FIG. 27  is an enlarged sectional side view of a main portion showing that a second holding means  10 ′ receives and holds the sheet bunch from the first holding means  7  in an initial position according to the second embodiment. On the other hand,  FIG. 28  is another enlarged sectional side view of the main portion showing that the second holding means  10 ′ passes the horizontal opening  50   b  and reaches the movable plate  16 J′ and the elevating plate  16 K′ to rotate and operate a drive motor  224  in a protruded condition. 
   A basic mechanical constitution for advancing and retreating (so-called swinging) the second holding means  10 ′ will be described with reference to  FIGS. 27 and 28 . In various drive systems, as shown in  FIG. 17 , in response to input/output signals from the CPU  120  and the memory means  121  such as ROM, RAM and the like, the parallel I/O  122  is operated and controlled. Furthermore, the swinging mechanism shown in  FIGS. 27 and 28  is supported by a movable frame fixed to the running member  95 ′ shown in  FIG. 25 , and moves as the running member  95 ′ moves. 
   First, when copying operation is started, the shutter plate  16 ′ is raised by the drive section  18  to open the horizontal opening  50   b , and the predetermined sheet bunch is discharged onto the accumulating tray  9 A or  9 B of the accumulation processing device unit  50 . When the second holding means  10 ′ returns to the initial position, the shutter plate  16 ′ is lowered to close the horizontal opening  50   b.    
   The second holding means  10 ′ has upper and lower holding levers  71 ′ and  72 ′ corresponding to the upper and lower holding levers  71  and  72  of the second holding means  10  of the first embodiment. The upper and lower holding levers  71 ′ and  72 ′ are advanced/retreated by the drive motor  224 . The drive motor  224  is interconnected to gears  225 ,  226  and  227  and a pinion gear  228  for transmitting the rotation of the motor. A pin  230  is eccentrically attached to a rotating plate  229  which coaxially rotates when the pinion gear  228  rotates. A follower arm  231  is also rotatably attached to the pinion  230 . For the other end of the pin  230 , one end of a rotating arm  234  is rotatably attached via a pin  232  to the follower arm  231 , and the rotating arm  234  can rotate about a fixed shaft  233  fixed to a movable frame (not shown). The other end of the rotating arm  234  is provided with an elongated hole  234 A for passing through a pin  235 . The pin  235  interconnects a lever support member  240  and the rotating arm  234  in such a manner that a portion of outer periphery of the pin  235  can be engaged to move along an elongated hole  237 A formed in a swinging plate  237  for advancing/retreating the upper and lower holding levers  71 ′ and  72 ′. 
   The swinging plate  237  is fixedly attached to the movable frame (not shown). The swinging plate  237  is also provided with a raindrop-shaped opening  237 B. The opening  237 B has therein a stopper plate  239  whose side is pressed with a predetermined contact pressure by a spring or another elastic member. Moreover, a pin  238  fixedly protruded from the support member  240  for supporting the upper and lower holding levers  71 ′ and  72 ′ can move along an outer side of the stopper plate  239  and an inner side of the opening  237 B. As shown in  FIG. 28 , the pin  238  passes along a large curved portion  237 C of the raindrop-shaped opening  237 B in a direction shown by an arrow, pushes and detaches the stopper plate  239  from one side of the opening against the contact pressure of the elastic member of the stopper plate  239 , further advances and returns to an original position shown in  FIG. 27 . On the other hand, the pin  238  fails to move in a direction opposite to the direction shown by the arrow because its passage is obstructed by the abutting stopper plate  239 . 
   The advancing/retreating of the upper and lower holding levers  71 ′ and  72 ′ of the second holding means  10 ′ will be described. In the retreated position of the upper and lower holding levers  71 ′ and  72 ′ shown in  FIG. 27 , one end of the rotating arm  234  having the pin  235  is retreated apart from the movable plate  16 J′. When the upper and lower levers  71 ′ and  72 ′ once hold the sheet bunch and move to back surfaces of the movable plate  16 J′ and the elevating plate  16 K′, the drive motor  224  is rotated in such a manner that the rotating plate  229  is rotated to the right as seen in  FIG. 27  (rotated clockwise). The follower arm  231  follows the rotation of the rotating plate  229  to rotate the rotating arm  234  about the fixed shaft  233  counterclockwise. Thereby, since the pin  235  advances along the elongated hole  237 A of the swinging plate  237  toward the movable plate  16 J′, the support member  240  is pushed forward. At this time, the pin  238  also moves forward along a path made by the stopper plate  239  and the opening  237 B, but changes its course to move downward along the large curved portion  237 C. Thereby, since the support member  240  is pushed downward, the upper and lower holding levers  71 ′ and  72 ′ are changed from an oblique upward direction for holding to a horizontal direction. 
     FIG. 28  shows that the pin  238  just passes the curved portion  237 C, and the upper and lower holding levers  71 ′ and  72 ′ push out the movable plate  16 J′ and are pushed outside while changing downward the holding direction. At this time, as aforementioned, the elevating plate  16 K′ is lowered by following the movement of the second holding means  10 ′. Furthermore, by rotating the drive motor  224 , the pin  238  advances in a direction shown by an arrow in  FIG. 28 . Therefore, the upper and lower holding levers  71 ′ and  72 ′ are placed in a substantially horizontal condition. At this time, by opening the upper and lower holding levers  71 ′ and  72 ′, the sheet bunch is dropped onto the accumulating tray  9 A or  9 B (the sheet bunch is so-called discharged). 
   When the drive motor  224  is further rotated, the pin  235  leaves apart from the movable plate  16 J′. Thereby, while pushing the stopper plate  239 , the pin  238  returns to the initial position shown in  FIG. 27 . The stopper plate  239  then abuts on one side of the opening  237 B via its elastic member again, thereby inhibiting the pin  235  from moving in reverse. In this manner, the upper and lower holding levers  71 ′ and  72 ′ return to the retreated position shown in  FIG. 27 , and the movable plate  16 J′ closes the opening  16 D′ via the elastic member  16 U shown in  FIG. 26 . 
   As aforementioned, the opening via which the holding means for holding the sheet bunch moves is controlled to open/close. Furthermore, the opening via which the holding means is protruded to discharge the sheets is provided with the locking mechanism. Therefore, the access from the outside is prevented, and a highly safe accumulation processing device can be provided. Additionally, the movable plate  16 J′ as the vertical rotating shutter forming the opening section for discharging the sheets cooperate with the elevating shutter or plate  16 K′ to operate the locking mechanism. Moreover, the elevating shutter is constituted to be able to rise/lower in response to the movement of the holding means. There can thus be provided a simple and low-cost sheet accumulation processing device having the shielding mechanism which does not require a complicated control.