Patent Publication Number: US-2006012098-A1

Title: Sheet folding and binding apparatus

Description:
CROSS-REFERECE TO RELATED APPLICATIONS  
      The present application claims priority and contains subject matter related to Japanese Patent Application No. 2004-209394 filed in the Japanese Patent Office on Jul. 16, 2004 and the entire contents of which are hereby incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates generally to a sheet folding and binding apparatus used in conjunction with an image forming apparatus such as a copying machine, a printer, etc.  
      2. Discussion of the Background  
      Binding apparatuses used in conjunction with an image forming apparatus generally receive sheets discharged from the image forming apparatus one after another, stack and jog the sheets, and then staple the stacked sheets at their one side edge portions.  
      A known binding system used in producing weekly magazines stacks and jogs printed sheets, and staples the sheets at their center portions by a staple device. The sheets are folded at their stapled center portions, and side edges of the folded sheets opposite the stapled and folded center portions thereof are cut off by a cutting device so as to be uniform.  
      In a known sheet folding and binding apparatus used in conjunction with an image forming apparatus, a sheet received from the image forming apparatus is folded at a center portion thereof or at two folding portions thereof to be like a letter Z in a cross section (so-called Z-folding) and is then bound. In the sheet folding and binding apparatus, the received sheet is conveyed to a folding part located at a lower part of the apparatus to be folded and is then conveyed to a binding part located at an upper part of the apparatus to be bound through a conveying path between the folding part and the binding part. The conveying path is relatively long, so that the apparatus is relatively large and expensive.  
     SUMMARY OF THE INVENTION  
      The present invention has been made in views of the above-discussed and other problems and addresses the above-discussed and other problems.  
      Preferred embodiments of the present invention provide a novel sheet folding and binding apparatus capable of folding a received sheet at a single folding portion or at two folding portions thereof, that is relatively compact and inexpensive.  
      According to an embodiment of the present invention, a sheet folding and binding apparatus connected with an image forming apparatus and operated based on an instruction from the image forming apparatus includes a receiving device configured to receive a sheet discharged from the image forming apparatus and to convey the sheet further, and a folding device configured to fold the sheet conveyed by the receiving device according to the instruction from the image forming apparatus either at a single folding portion or at two folding portions of the sheet and to convey the sheet. The folding device includes a first folding part configured to fold the sheet conveyed by the receiving device, when folding the sheet at a single folding portion thereof, at the single folding portion thereof, and when folding the sheet at two folding portions thereof, at a first folding portion of the two folding portions thereof, and to convey the sheet folded at the single folding portion thereof with the folded single folding portion thereof placed as a leading edge of the sheet and the sheet folded at the first folding portion of the two folding portions thereof with the folded first folding portion thereof placed as a leading edge of the sheet, and a second folding part configured to convey the sheet folded at the single folding portion thereof and conveyed with the folded single folding portion thereof placed as the leading edge of the sheet by the first folding part further, without folding the sheet, and to fold the sheet folded at the first folding portion of the two folding portions thereof and conveyed with the folded first folding portion thereof placed as the leading edge of the sheet by the first folding part, at a second folding portion of the two folding portions thereof and to convey the sheet folded at the first folding portion and the second folding portion thereof with the folded second folding portion thereof placed as a leading edge of the sheet. The apparatus further includes a receiving/jogging device including a tray and configured to receive the sheet conveyed by the folding device one after another on the tray and to jog the sheet one after another so as to be stacked into a stack of the sheet on the tray, a binding device arranged at one end side of the tray of the receiving/jogging device and configured to bind the stack of the sheet on the tray of the receiving/jogging device, and a discharge device configured to discharge the stack of the sheet on the tray of the receiving/jogging device, which has been bound by the binding device. The sheet folded at the single folding portion thereof is bound by the binding device at an edge portion thereof at the folded single folding portion side, and the sheet folded at the first folding portion and the second folding portion thereof is bound by the binding device at an edge portion thereof opposite the folded second folding portion thereof.  
      In the sheet folding and binding apparatus, the second folding part of the folding device may be configured to discharge the sheet folded at the single folding portion thereof and conveyed with the folded single folding portion thereof placed as the leading edge of the sheet by the first folding part, without holding the sheet, directly onto the tray of the receiving/jogging device from an end side of the tray opposite the one end side thereof where the binding device is arranged, so that the sheet folded at the single folding portion thereof is received by the receiving/jogging device on the tray thereof with the folded single folding portion thereof located at the one end side of the tray where the binding device is arranged and thereby the sheet is bound by the binding device at an edge portion thereof at the folded single folding portion side.  
      The sheet folding and binding apparatus may comprise a reversing device arranged downstream of the second folding part of the folding device in a direction in which the sheet folded at the first folding portion and the second folding portion thereof is conveyed by the second folding part with the folded second folding portion thereof placed as the leading edge of the sheet and configured to reverse the sheet conveyed by the second folding part and to discharge the sheet directly onto the tray of the receiving/jogging device from the end side of the tray opposite the one end side thereof where the binding device is arranged, so that the sheet folded at the first folding portion and the second folding portion thereof is received by the receiving/jogging device on the tray thereof with an end of the sheet opposite the folded second folding portion thereof located at the one end side of the tray where the binding device is arranged and thereby the sheet folded at the first folding portion and the second folding portion thereof is bound by the binding device at the edge portion thereof opposite the folded second folding portion thereof.  
      The sheet folding and binding apparatus may comprise a discharge path arranged downstream of the second folding part of the folding device in a direction in which the sheet folded at the first folding portion and the second folding portion thereof is conveyed by the second folding part with the folded second folding portion thereof placed as the leading edge of the sheet and configured to discharge the sheet folded at the first folding portion and the second folding portion thereof and conveyed by the second folding part with the folded second folding portion thereof placed as the leading edge of the sheet onto the tray of the receiving/jogging device from the one end side of the tray where the binding device is arranged, so that the sheet folded at the first folding portion and the second folding portion thereof is received by the receiving/jogging device on the tray thereof with an end of the sheet opposite the folded second folding portion thereof located at the one end side of the tray where the binding device is arranged and thereby the sheet folded at the first folding portion and the second folding portion thereof is bound by the binding device at the edge portion thereof opposite the folded second folding portion thereof.  
      The sheet folding and binding apparatus may comprise a first conveying path configured to convey the sheet conveyed by the receiving device to the folding device, a second conveying path configured to convey the sheet conveyed by the receiving device, without passing the folding device, directly onto the tray of the receiving/jogging device as an unfolded sheet from the one end side of the tray where the binding device is arranged, and a switching device configured to switch a conveying direction of the sheet conveyed by the receiving device according to the instruction from the image forming apparatus, when folding the sheet at a single folding portion or at two folding portions thereof, to the first conveying path, and when conveying the sheet, without folding the sheet, directly onto the tray of the receiving/jogging device as an unfolded sheet, to the second conveying path, so that the sheet as an unfolded sheet and the sheet folded at the single folding portion or at the two folding portions thereof may be mixed in the stack of the sheet on the tray.  
      The sheet folding and binding apparatus may comprise a sheet conveying direction correction device arranged between the receiving device and the first folding part of the folding device and configured to correct a deviation in a conveying direction of the sheet conveyed by the receiving device so that the sheet is folded by the first folding part of the folding device in such a manner that, when the sheet is folded at the single folding portion thereof, the folded single folding portion thereof, and when the sheet is folded at the first folding portion of the two folding portions thereof, the folded first folding portion thereof is perpendicular to side edges of the sheet. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      A more complete appreciation of the present invention and many of the attended advantages thereof will be readily obtained as the present invention becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:  
       FIG. 1  is a diagram schematically illustrating a system in which a sheet folding and binding apparatus according to an embodiment of the present invention is connected with an image forming apparatus;  
       FIG. 2A  is a diagram illustrating an example of folding and binding sheets in the sheet folding and binding apparatus, in which each sheet is folded at a single folding portion thereof, and the folded sheet is stacked one upon another to be bound at an edge portion thereof at the folded portion side;  
       FIG. 2B  is a diagram illustrating another example of folding and binding sheets in the sheet folding and binding apparatus, in which each sheet is folded at two folding portions thereof to be like a letter Z in a cross section, and the folded sheet is stacked one upon another to be bound at an edge portion thereof opposite the folded portion side;  
       FIG. 2C  is a diagram illustrating another example of folding and binding sheets in the sheet folding and binding apparatus, in which each sheet is stacked one upon another, without being folded, to be bound at an edge portion thereof;  
       FIG. 2D  is a diagram illustrating another example of folding and binding sheets in the sheet folding and binding apparatus, in which a sheet folded at two folding portions thereof to be like a letter Z in a cross section is mixed in unfolded sheets to be bound;  
       FIG. 3  is a diagram schematically illustrating an exemplary construction of the sheet folding and binding apparatus;  
       FIG. 4  is a diagram illustrating an exemplary mechanism of moving a roller pair of a second guide part of a folding part of the sheet folding and binding apparatus;  
       FIG. 5A  is a portion of a flowchart of an exemplary operation of the sheet folding and binding apparatus of  FIG. 3 ;  
       FIG. 5B  is another portion of the flowchart of the exemplary operation of the sheet folding and binding apparatus of  FIG. 3 ;  
       FIG. 5C  is still another portion of the flowchart of the exemplary operation of the sheet folding and binding apparatus of  FIG. 3 ;  
       FIG. 5D  is still another portion of the flowchart of the exemplary operation of the sheet folding and binding apparatus of  FIG. 3 ;  
       FIG. 6  is a diagram illustrating an exemplary construction of a sheet folding and binding apparatus according to another embodiment of the present invention;  
       FIG. 7A  is a portion of a flowchart of an exemplary operation of the sheet folding and binding apparatus of  FIG. 6 ;  
       FIG. 7B  is another portion of the flowchart of the exemplary operation of the sheet folding and binding apparatus of  FIG. 6 ;  
       FIG. 7C  is still another portion of the flowchart of the exemplary operation of the sheet folding and binding apparatus of  FIG. 6 ;  
       FIG. 7D  is still another portion of the flowchart of the exemplary operation of the sheet folding and binding apparatus of  FIG. 6 ;  
       FIG. 7E  is another portion of the flowchart of the exemplary operation of the sheet folding and binding apparatus of  FIG. 6 ;  
       FIG. 7F  is still another portion of the flowchart of the exemplary operation of the sheet folding and binding apparatus of  FIG. 6 ; and  
       FIG. 7G  is still another portion of the flowchart of the exemplary operation of the sheet folding and binding apparatus of  FIG. 6 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, preferred embodiments of the present invention are described.  
       FIG. 1  schematically illustrates a system in which a sheet folding and binding apparatus according to an embodiment of the present invention is connected with an image forming apparatus such as a so-called multi-function digital copier.  
      An image forming apparatus  1  inputs image data from an original document, a PC, and/or a network, stores the inputted image data, forms images of the inputted image data on print sheets, and discharges the sheets one after another. A sheet binding apparatus  2  as the sheet folding and binding apparatus of the present invention receives the sheets discharged from the image forming apparatus  1  one after another, folds the sheets one after another, and binds the sheets. An instruction of folding and/or binding the sheets is inputted by a user from an operation panel of the image forming apparatus  1  and is transmitted to the sheet binding apparatus  2 . The sheet binding apparatus  2  folds and/or binds the sheets discharged from the image forming apparatus  1  according to the instruction received from the image forming apparatus  1 .  
      The instruction includes at least information for each sheet as to whether to fold and bind the sheet or to bind the sheet without folding, whether to fold the sheet at a single folding portion thereof (so-called two-folding) or at two folding portions thereof (so-called Z-folding), the folding portion of the sheet such as, in two-folding, the center portion of the sheet, etc., and in Z-folding, portions corresponding to one-fourth and one-half of the length of the sheet from the leading edge of the sheet, etc., the size of the sheet such as A3, A4, etc., and whether to bind the sheet at an edge portion thereof at the side where the folded portion is located or at the opposite side, and information as to the number of sheets to be bound and the number of sets of a bound stack of sheets.  
       FIG. 2A ,  FIG. 2B ,  FIG. 2C  and  FIG. 2D  illustrate examples of folding and binding sheets in the sheet binding apparatus  2 .  FIG. 2A  illustrates a case that a sheet is folded at a single folding portion thereof (in the example, at the center portion of the sheet) and is bound at an edge portion thereof at the folded single folding portion side.  FIG. 2B  illustrates a case that a sheet is folded at two folding portions thereof to be like a letter Z in a cross section (in the example, at first at a portion of the sheet one-fourth of the length of the sheet from the leading edge of the sheet and secondly at a portion of the sheet one-fourth of the length of the sheet from the portion folded at first) and is bound at an edge portion thereof opposite the folded portions thereof.  FIG. 2C  illustrates a case that unfolded sheets are bound at their edge portions.  FIG. 2D  illustrates a case that a sheet folded at two folding portions thereof is mixed in unfolded sheets to be bound.  
       FIG. 3  schematically illustrates an exemplary construction of the sheet binding apparatus  2 .  
      An entry part  4  serves as a receiving device of the present invention and is configured to receive a sheet  3  discharged from the image forming apparatus  1  and to convey the sheet  3  further. A first path  8  serves as a first conveying path of the present invention and is configured to guide and to convey the sheet  3  conveyed by the entry part  4 . A folding part  12  serves as a folding device of the present invention and is configured to fold the sheet  3  conveyed by the first path  8  at a single folding portion or at two folding portions of the sheet  3  and to convey the sheet  3  further. A reversing part  26  arranged downstream of the folding part  12  serves as a reversing device of the present invention and is configured to reverse the sheet  3  conveyed from the folding part  12 . A second path  30  serves as a second conveying path of the present invention and is configured to guide and to convey the sheet  3 . A receiving/jogging part  33  including a tray  34  serves as a receiving/jogging device of the present invention and is configured to receive the sheet  3  conveyed by the folding part  12  one after another on the tray  34  and to jog the sheet  3  so as to be stacked into a stack of the sheet  3  on the tray  34 . A binding part  44  arranged at an end of the tray  34  of the receiving/jogging part  33  serves as a binding device of the present invention and is configured to bind the stack of the sheet  3  on the tray  34  of the receiving/jogging part  33 . A discharging part  41  serves as a discharge device of the present invention and is configured to discharge the bound stack of the sheet  3  on the tray  34  of the receiving/jogging part  33 . A controller  70  is configured to receive an instruction from the image forming apparatus  1  and to control respective parts of the sheet binding apparatus  2  according to the received instruction.  
      The entry part  4  includes an entry sensor  5  configured to detect the sheet  3  discharged from the image forming apparatus  1  and entered into an opening part of the entry part  4 , an entry roller pair  6  configured to receive the sheet  3  and to convey the sheet  3 , and a sheet conveying path switching device  7  configured to switch the direction in which the sheet  3  conveyed by the entry roller pair  6  is conveyed between the first path  8  and the second path  30  according to detect information of the entry sensor  5  and the instruction received from the image forming apparatus  1 .  
      The first path  8  is configured to convey the sheet  3  conveyed by the entry roller pair  6  to the folding part  12 . The first path  8  includes a conveying roller pair  9  configured to convey the sheet  3  conveyed by the entry roller pair  6 , a registration sensor  10  configured to detect the leading edge of the sheet  3  conveyed by the conveying roller pair  9 , and a registration roller pair  11  configured to be intermittently driven by a control drive part (not shown) according to detect information of the registration sensor  10  to correct a deviation in the conveying direction of the sheet  3 . After the leading edge of the sheet  3  has been detected with the registration sensor  10 , a predetermined time later, the registration roller pair  11  is stopped to be rotated and after a predetermined time, is rotated again. The leading edge of the sheet  3  impinges upon the registration roller pair  11  stopped to be rotated, so that the sheet  3  is bulged between the registration roller pair  11  and the conveying roller pair  9  and thereby a deviation in the conveying direction of the sheet  3 , such as skewing, is corrected. By correcting the deviation in the conveying direction of the sheet  3 , the sheet  3  is folded by the folding part  12  in such a manner that the folded single folding portion and the folded two folding portions of the sheet  3  are perpendicular to the side edges of the sheet  3 .  
      The folding part  12  includes a first roller pair  13  configured to convey the sheet  3  conveyed by the first conveying path  8 , a first guide part  18  configured to guide the sheet  3  being conveyed by the first roller pair  13 , a stopper plate  20  arranged in the first guide part  18  to serve as a stopping device of the present invention and is configured to stop the sheet  3  being conveyed by the first roller pair  13  and guided by the first guide part  18 , a second roller pair  14  configured to fold the sheet  3  stopped by the stopper plate  20  at a portion of the sheet  3  and to convey the sheet  3 , and a sensor  16  arranged at the entrance of the first guide part  18  to detect the leading edge of the sheet  3  conveyed by the first roller pair  13 . The folding part  12  further includes a second guide part  21  configured to guide the sheet  3  being conveyed by the second roller pair  14 , a roller pair  23  arranged in the second guide part  21  as a sheet stopping/conveying device of the present invention and is configured to stop and to convey the sheet  3  being conveyed by the second roller pair  14  and guided by the second guide part  21 , a third roller pair  15  configured to fold the sheet  3  stopped by the roller pair  23  at another portion of the sheet  3  and to convey the sheet  3 , and a sensor  54  arranged at the entrance of the second guide part  21  to detect the leading edge of the sheet  3  conveyed by the second roller pair  14 .  
      The second guide part  21  is configured to guide the sheet  3  being conveyed by the second roller pair  14  and conveyed by the roller pair  23  further to be discharged directly onto the tray  34  of the receiving/jogging part  33  from the end side of the tray  34  opposite the end side thereof where the binding part  44  is arranged.  
      The first roller pair  13 , the first guide part  18 , the stopper plate  20 , and the second roller pair  14  constitute a first folding part of the present invention, and the second roller pair  14 , the second guide part  21 , the roller pair  23 , and the third roller pair  15  constitute a second folding part of the present invention. When folding the sheet  3  received by the entry part  4  at a single folding portion of the sheet  3  according to the instruction from the image forming apparatus  1 , the sheet  3  is folded by the first folding part at the single folding portion of the sheet  3  and is conveyed by the first folding part to the second folding part, and thereafter, the sheet  3  is discharged by the second folding part directly onto the tray  34  of the receiving/jogging part  33 . When folding the sheet  3  received by the entry part  4  at two folding portions of the sheet  3 , the sheet  3  is folded by the first folding part at a first folding portion of the two folding portions thereof and is conveyed by the first folding part to the second folding part, and thereafter, the sheet  3  is folded by the second folding part at a second folding portion of the two folding portions thereof.  
      The first guide part  18  includes two guide plates arranged to form a sheet path, through which the sheet  3  conveyed by the first roller pair  13  is conveyed. The stopper plate  20  is provided to a belt arranged below the guide plates and protrudes the guide plates through grooves provided in the guide plates to stop the sheet  3  being conveyed in the sheet path of the second guide part  18 . The stopper plate  20  is configured to be moved in the grooves of the guide plates by driving of the belt with a stepping motor  19 , and is moved, according to the instruction received from the image forming apparatus  1 , to a stopping position to regulate the leading edge of the sheet  3  being conveyed by the first roller pair  13  and guided by the first guide part  18  and to thereby stop the sheet  3 .  
      When the leading edge of the sheet  3  being conveyed by the first roller pair  13  and guided by the first guide part  18  has impinged upon the stopper plate  20 , the sheet  3  is caused to bulge at a portion thereof located between the nip of the first roller pair  13  and the entrance of the sheet path formed by the two guide plates of the first guide part  18  toward the nip of the second roller pair  14 . The bulged portion of the sheet  3  is pinched in the nip of the second roller pair  14  and thereby the sheet  3  is folded by the second roller pair  14  at the bulged portion of the sheet  3  pinched in the second roller pair  14 . The sheet  3  is conveyed to the second guide part  21  with the second roller pair  14  with the folded portion of the sheet  3  placed as the leading edge of the sheet  3 .  
      The position where the stopper plate  20  is moved to regulate the leading edge of the sheet  3  being conveyed by the first roller pair  13  and guided by the first guide part  18  to stop the sheet  3  is determined based upon the position of the folding portion of the sheet  3  included in the instruction from the image forming apparatus  1 . In folding the sheet  3  at a single folding portion thereof, when the single folding portion of the sheet  3  is the center portion of the sheet  3 , for example, the stopper plate  20  is moved to the position separate from the nip of the first roller pair  13  by the distance corresponding to the half of the length of the sheet  3  in the direction in which the sheet  3  is conveyed, and thereby the sheet  3  is folded by the second roller pair  14  at the center portion of the sheet  3 . In folding the sheet  3  at two folding portions thereof, when the first folding portion of the two folding portions of the sheet  3  is the portion of the sheet  3  one-fourth of the length of the sheet  3  from the leading edge thereof, for example, the stopper plate  20  is moved to the position separate from the nip of the first roller pair  13  by the distance corresponding to one-fourth of the length of the sheet  3 , and thereby the sheet  3  is folded by the second roller pair  14  at the portion one-fourth of the length of the sheet  3  from the leading edge thereof.  
      A roller pair arranged in a fixed position may be used, instead of the stopper plate  20 , as the stopping device to stop the sheet  3  being conveyed by the first roller pair  13  and guided by the first guide part  18 . The roller pair is rotated to convey the sheet  3  being conveyed by the first roller pair  13  and guided by the first guide part  18  and is rotated in reverse to stop the sheet  3 . When folding the sheet  3  at two folding portions thereof, the roller pair is rotated in reverse after detecting the leading edge of the sheet  3  with the sensor  16  in the timing that the sheet  3  has been conveyed by the first roller pair  13  the distance corresponding to the length of the sheet  3  from the leading edge to the first folding portion of the two folding portions of the sheet  3 , so that the sheet  3  is caused to bulge at the first folding portion thereof located between the nip of the first roller pair  13  and the entrance of the sheet path formed by the two plates of the first guide part  18  toward the nip of the second roller pair  14 , the bulged first folding portion of the sheet  3  is pinched in the nip of the second roller pair  14 , and thereby the sheet  3  is folded by the second roller pair  14  at the first folding portion thereof and is conveyed further. When folding the sheet  3  at a single folding portion thereof, the roller pair is rotated in reverse in the timing that the sheet  3  has been conveyed by the first roller pair  13  the distance corresponding to the length of the sheet  3  from the leading edge to the single folding portion thereof and thereby the sheet  3  is similarly folded by the second roller pair  14  at the single folding portion thereof.  
      The second guide part  21  includes two guide plates arranged to form a sheet path, through which the sheet  3  conveyed by the second roller pair  14  is conveyed. Grooves are formed in the guide plates, and the roller pair  23  arranged in the second guide part  21  is configured to be moved in the grooves to a stopping position according to the instruction received from the image forming apparatus  1  to regulate the leading edge of the sheet  3  being conveyed by the second roller pair  14  and guided by the second guided part  21  to stop the sheet  3 .  
       FIG. 4  illustrates an exemplary mechanism of moving the roller pair  23 . The guide plates of the second guide part  21  are attached to side plates of the main body of the binding apparatus  2 . The roller pair  23  is rotatably mounted to a plate  62  fixed to an axis  64 , which is rotatably supported by bearings at parts of the side plates of the main body corresponding to the center of an arc of the guide plates. The roller pair  23  is rotated, is stopped to be rotated, and is rotated in reverse by driving of a gear  61  and a gear  60  with a stepping motor  22  fixed to the plate  62 . A gear  63  integrated with the plate  62  is fixed to an axis  64  rotatably supported with bearings at the side plates of the main body, and is engaged with a worm gear  67 . The worm gear  67  is driven by driving of a gear  65  engaging with a gear  66  fixed to an axis of a stepping motor  68  mounted to the side plates of the main body. The roller pair  23  is moved with driving of the gears  66 ,  65 ,  67  and  63  by the stepping motor  68 .  
      When folding the sheet  3  at two folding portions thereof, the roller pair  23  is moved to a stopping position separate from the nip of the second roller pair  14  by the distance corresponding to the length of the sheet  3  from the first folding portion to the second folding portion of the two folding portions of the sheet  3 , and is stopped to be rotated to regulate the leading edge (the folded first folding portion) of the sheet  3  folded at the first folding portion and being conveyed by the second roller pair  14  and guided by the second guide part  21 , so that the sheet  3  is stopped in the timing that the sheet  3  has been conveyed by the second roller pair  14  by the distance corresponding to the length of the sheet  3  from the first folding portion to the second folding portion of the sheet  3 . Thereby, the second folding portion of the sheet  3  located between the entrance of the sheet path of the second guide part  21  and the nip of the third roller pair  15  is caused to bulge toward the nip of the third roller pair  15 , the bulged second folding portion of the sheet  3  is pinched in the nip of the third roller pair  15 , and thereby the sheet  3  is folded by the third roller pair  15  at the second folding portion of the sheet  3 . The sheet  3  is conveyed by the third roller pair  15  with the folded second folding portion thereof placed as the leading edge of the sheet  3  to the reversing part  26  arranged downstream of the third roller pair  15 .  
      When folding the sheet  3  at a single folding portion thereof, the roller pair  23  is moved to a predetermined conveying position and is rotated in the arrow direction in  FIG. 3  to convey the sheet  3  folded at the single folding portion thereof and being conveyed by the second roller pair  14  and guided by the second guide part  21  further, without stopping the sheet  3 , so that the sheet  3  folded at the single folding portion thereof is conveyed by the roller pair  23  to be discharged onto the tray  34  of the receiving/jogging part  33  with the folded single folding portion thereof placed as the leading edge of the sheet  3  from the end side of the tray  34  opposite the end side thereof where the binding part  44  is arranged. Thereby, the sheet  3  folded at the single folding portion thereof is received on the tray  34  of the receiving/jogging part  33  with the folded single folding portion thereof located at the end side of the tray  34  where the binding part  44  is arranged, so that the sheet  3  is bound by the binding part  44  at the edge portion thereof at the folded single folding portion side.  
      The roller pair  23  may be alternatively fixed. When folding the sheet  3  at two folding portions thereof, the roller pair  23  is rotated in the arrow direction in  FIG. 3  to convey the sheet  3  folded at the first folding portion thereof and being conveyed by the second roller pair  14  and guided by the second guide part  21  and is rotated in reverse in the timing that the sheet  3  has been conveyed by the second roller pair  14  the distance corresponding to the length of the sheet  3  from the first folding portion to the second folding portion of the sheet  3 . Thereby, the second folding portion of the sheet  3  located between the entrance of the sheet path of the second guide part  21  and the nip of the third roller pair  15  is caused to bulge toward the nip of the third roller pair  15 , the bulged second folding portion of the sheet  3  is pinched in the nip of the third roller pair  15 , and thereby the sheet  3  is folded by the third roller pair  15  at the second folding portion of the sheet  3 . The sheet  3  is conveyed by the third roller pair  15  with the folded second folding portion thereof placed as the leading edge thereof to the reversing part  26  arranged downstream of the third roller pair  15 . When folding the sheet  3  at a single folding portion thereof, the roller pair  23  is rotated in the arrow direction in  FIG. 3  to convey the sheet  3  folded at the single folding portion thereof and being conveyed by the second roller pair  14  and guided by the second guide part  21  further, without stopping the sheet  3 . Thereby, the sheet  3  folded at the single folding portion thereof is conveyed by the roller pair  23  and is discharged onto the tray  34  of the receiving/jogging part  33 .  
      The reversing part  26  includes a sheet path into which the sheet  3  conveyed by the third roller pair  15  with the folded second folding portion of the sheet  3  placed as the leading edge thereof is conveyed, a sensor  25  arranged at the entrance of the sheet path, and a guide roller pair  27  arranged along the sheet path. The guide roller pair  27  starts to rotate in the arrow direction in  FIG. 3  upon detecting the leading edge of the sheet  3  conveyed from the third roller pair  15  with the sensor  25  to convey the sheet  3  into the sheet path. Upon detecting the trailing edge of the sheet  3  with the sensor  25 , the guide roller pair  27  is rotated in reverse, so that the sheet  3  is reversed by the guide roller pair  27  to be conveyed with the end thereof opposite the folded second folding portion thereof placed as the leading edge of the sheet  3 . The reversing part  26  includes a roller pair  28  arranged to convey the sheet  3  reversed by the guide roller pair  27  further and a sheet path arranged downstream of the roller pair  28  to guide the sheet  3  conveyed by the roller pair  28  to be discharged onto the tray  34  of the receiving/jogging part  33  from the end side of the tray  34  opposite the end side thereof where the binding part  44  is arranged, so that the sheet  3  folded at the two folding portions thereof is received on the tray  34  of the receiving/jogging part  33  with the end thereof opposite the folded second folding portion thereof located at the end side of tray  34  where the binding part  44  is arranged. Thereby, the sheet  3  folded at the two folding portions thereof is bound by the binding part  44  at the edge portion thereof opposite the folded second folding portion thereof.  
      A sensor  29  is arranged at the end of the sheet path arranged downstream of the roller pair  28  to detect the leading edge of the sheet  3  conveyed by the roller pair  28 .  
      The second conveying path  30  is configured to guide the sheet  3  conveyed by the entry roller pair  6  and guided by the switching member  7  to be conveyed thereto to be directly discharged onto the tray  34  of the receiving/jogging part  33  as an unfolded sheet from the end side of the tray  34  where the binding part  44  is arranged. A discharge roller pair  31  is arranged at the end of the second conveying path  30  to discharge the sheet  3  onto the tray  34 , and a discharge sensor  32  is arranged to detect the trailing edge of the sheet  3 .  
      The receiving/jogging part  33  includes an end plate  37  arranged at the end side of the tray  34  opposite the end thereof where the binding part  44  is arranged. The end plate  37  is driven by a stepping motor (not shown) to reciprocate in the direction in which the sheet  3  is discharged onto the tray  34  from the second guide part  21  and the reversing part  26  to jog the sheet  3  in the conveying direction of the sheet  3 . A side plate (not shown) is arranged at the rear side of the tray  34  in the widthwise direction of the tray  34 , and a side guide plate  38  is arranged at this side of the tray  34  in the widthwise direction of the tray  34  and is driven by a stepping motor (not shown) to reciprocate in the widthwise direction of the tray  34  to jog the sheet  3  in the widthwise direction thereof.  
      The binding part  44  is arranged at the tip end of the tray  34  of the receiving/jogging part  33  in the direction in which the sheet  3  is discharged onto the tray  34  from the second guide part  21  and the reversing part  26 . The binding part  44  includes a stopping plate  39 , against which the sheet  3  discharged onto the tray  34  is jogged by the end plate  37  so that the leading edge of the sheet  3  discharged from the second guide part  21  and the reversing part  26  is aligned with the stopping plate  39 , and a binding device (not shown) configured to bind a stack of the sheet  3  on the tray  34 . A known device, such as a stapler, etc., may be used for the binding device. Further, a plurality of binding devices may be arranged.  
      The discharge part  41  includes an arm mechanism (not shown) configured to move the stopping plate  39  of the binding part  44  toward the end plate  37  of the receiving/jogging part  33  after the stack of the sheet  3  on the tray  34  has been bound by the binding device of the binding part  44 . After the stopping plate  39  has been moved toward the end plate  37  and thereby the stack of the sheet  3  on the tray  34  has been pushed toward the end plate  37 , the edge side of the tray  34  at the side of the binding part  44  is lowered to the position indicated by a two-dot-dashed line in  FIG. 3  with an axis  36  at the other end side of the tray  34  serving as a fulcrum, so that the stack of sheet  3  on the tray  34  is moved toward a discharge roller pair  43  arranged under the binding part  44 , and is conveyed by the discharge roller pair  43  to a discharge tray (not shown). A sheet detect sensor  40  is arranged under the tray  34  to detect existence of the stack of the sheet  3  on the tray  34 , and a sensor  42  is arranged near the discharge roller pair  43  to detect discharging of the stack of the sheet  3  from the tray  34 .  
      The receiving/jogging part  33  may be configured such that the end side of the tray  34  at the side of the end plate  37  is lowered so that the stack of the sheet  3  on the tray  34  is discharged to the side opposite the binding part  44 .  
       FIG. 5A  through  FIG. 5D  illustrate a flowchart of an exemplary operation of the binding apparatus  2 .  
      When the binding apparatus  2  is turned on, the entry roller pair  6  of the entry part  4 , the conveying roller pair  9  and the registration roller pair  11  of the first path  8 , the first roller pair  13 , the second roller pair  14  and the third roller pair  15  of the folding part  12 , and the discharge roller pair  31  of the second path  30  start to rotate. The switching member  7  of the entry part  4  is moved to the p position in which the sheet  3  conveyed by the entry roller pair  6  is conveyed to the second path  30 , the tray  34  of the receiving/jogging part  33  is moved to the upper position (indicated by a solid line in  FIG. 3 ), and the end plate  37  and the side guide plate  38  of the receiving/jogging part  33  are moved to respective start positions (the most outside positions).  
      When the sheet  3  discharged from the image forming apparatus  1  and put into the opening of the entry part  4  of the binding apparatus  2  is detected with the entry sensor  5  (Yes in step S 1 ), whether the sheet  3  is to be folded and bound or to be bound, without being folded, is determined according to the instruction received from the image forming apparatus  1  (step S 2 ). When it has been determined in step S 2  that the sheet  3  is to be folded and bound, the switching member  7  is switched to the q position (step S 3 ), so that the sheet  3  is conveyed to the first path  8 .  
      The sheet  3  conveyed to the first path  8  is conveyed with the conveying roller pair  9 , and when the leading edge of the sheet  3  has been detected by the sensor  10  (Yes in step S 4 ), after a predetermined time, the registration roller pair  11  is stopped to be rotated and after a predetermined time, is rotated again (step S 5 ). By such an intermittent motion of the registration roller pair  11 , a deviation in the conveying direction of the sheet  3 , such as skewing, is corrected, and thereby precise folding and binding of the sheet  3  is realized.  
      Thereafter, the sheet  3  is conveyed with the first roller pair  13  to the first guide part  18 . When the leading edge of the sheet  3  has been detected with the sensor  16  (Yes in step S 6 ), whether the sheet  3  is to be folded at a single folding portion (in two-folding) or at two folding portions thereof (in Z-folding) is determined according to the instruction received from the image forming apparatus  1  (step S 7 ).  
      When it has been determined in step S 7  that the sheet  3  is to be folded at two folding portions thereof (in Z-folding), the positions of the two folding portions of the sheet  3  are determined according to the instruction received from the image forming apparatus  1 , and the stopper plate  20  of the first guide part  18  is moved by driving of the stepping motor  19  to the position separate from the nip of the first roller pair  13  by the distance corresponding to the length of the sheet  3  from the leading edge to the first folding portion of the two folding portions of the sheet  3  and the roller pair  23  of the second guide part  21  is moved to the stopping position separate from the nip of the second roller pair  14  by the distance corresponding to the length of the sheet  3  from the first folding portion to the second folding portion of the sheet  3  and is stopped to be rotated (step S 8 ). Thereby, the sheet  3  being conveyed by the first roller pair  13  is stopped in the timing that the sheet  3  has been conveyed by the first roller pair  13  the distance corresponding to the length of the sheet  3  from the leading edge to the first folding portion of the sheet  3 , so that the sheet  3  is folded by the second roller pair  14  at the first folding portion of the two folding portions thereof and is conveyed by the second roller pair to the second guide part  21 , and thereafter, the sheet  3  being conveyed by the second roller pair  14  is stopped in the timing that the sheet  3  has been conveyed by the second roller pair  14  by the distance corresponding to the length of the sheet  3  from the first folding portion to the second folding portion of the sheet  3 , so that the sheet  3  is folded by the third roller pair  15  at the second folding portion thereof and is conveyed by the third roller pair  15  to the reversing part  26 . The stopper plate  20  and the roller pair  23  may be moved in advance to respective stopping positions.  
      When the leading edge of the sheet  3  folded at the second folding portion thereof and conveyed by the third roller pair  15  has been detected by the sensor  25  (Yes in step S 9 ), the guide roller pair  27  of the reversing part  26  is rotated in the arrow direction in  FIG. 3  (step S 10 ), so that the sheet  3  is conveyed into the sheet path of the reversing part  26 . When the trailing edge of the sheet  3  has been detected by the sensor  25  (Yes in step S 11 ), the roller pair  27  is rotated in reverse (step S 12 ), so that the sheet  3  is reversed to the roller pair  28  and is conveyed by the roller pair  28  to be discharged onto the tray  34  of the receiving/jogging part  33 . When the trailing edge of the sheet  3  has been detected with the sensor  29  (Yes in step S 13 ), the sheet jogging mechanism (the end plate  37 , etc.) of the receiving/jogging part  33  is operated (step S 14 ).  
      When it has been determined in step S 7  that the sheet  3  is to be folded at a single folding portion thereof (in two-folding), the position of the single folding portion of the sheet  3  is determined according to the instruction received from the image forming apparatus  1 , and the stopper plate  20  of the first guide part  18  is moved by driving of the stepping motor  19  to the position separate from the nip of the first roller pair  13  by the distance corresponding to the length of the sheet  3  from the leading edge to the single folding portion of the sheet  3  and the roller pair  23  of the second guide part  21  is moved to the predetermined conveying position and is rotated in the arrow direction in  FIG. 3  (step S 15 ). Thereby, the sheet  3  being conveyed by the first roller pair  13  is stopped by the stopper plate  20  in the timing that the sheet  3  has been conveyed by the first roller pair  13  by the distance corresponding to the length of the sheet  3  from the leading edge to the single folding portion of the sheet  3 , so that the sheet  3  is fold by the second roller pair  14  at the single folding portion thereof and is conveyed by the second roller pair  14  to the second guide part  21  and thereafter, the sheet  3  is conveyed by the roller pair  23  rotating in the arrow direction in  FIG. 3  and is guided by the second guide part  21  to be discharged onto the tray  34  of the receiving/jogging part  33 . When the trailing edge of the sheet  3  has been detected with the sensor  24  (Yes in step S 16 ), the jogging mechanism of the receiving/jogging part  33  is operated (step S 14 ).  
      When it has been determined in step S 2  that the sheet  3  is to be bound without being folded, the switching member  7  is switched to the p position (step S 17 ), so that the sheet  3  is conveyed to the second path  30 . The sheet  3  is conveyed by the discharge roller pair  31  and is discharged onto the tray  34  of the receiving/jogging part  33  as an unfolded sheet. When the trailing edge of the sheet  3  has been detected with the sensor  32  (Yes in step S 18 ), the jogging mechanism of the receiving/jogging  33  is operated (step S 14 ).  
      The sheet  3  discharged onto the tray  34  of the receiving/jogging part  33  from the reversing part  26  or the second guide part  21  impinges upon the stopping plate  39  of the binding part  44  and is aligned with the stopping plate  39  by the reciprocating movement of the end plate  37  of the receiving/jogging part  33  against the stopping plate  39 . The sheet  3  is also aligned with the side plate of the receiving/jogging part  33  at the rear side of the tray  34  in the widthwise direction of the tray  34  by the reciprocating movement of the side guide plate  38  against the side plate.  
      The sheet  3  discharged onto the tray  34  of the receiving/jogging part  33  from the second path  30  impinges upon the end plate  37  and aligned with the stopping plate  39  by the reciprocating movement of the end plate  37  in a similar manner.  
      Thereafter, it is determined if the sheet  3  discharged onto the tray  34  of the receiving/jogging part  33  is the last sheet to be bound or if a predetermined number of the sheet  3  has been discharged onto tray  34 , according to the instruction received from the image forming apparatus  1  (step S 19 ). When it has been determined that the sheet  3  is the last sheet to be bound or the predetermined number of the sheet  3  has been discharged onto the tray  34  of the receiving/jogging part  33  (Yes in step S 19 ), the end plate  37  is moved to the jogging position at the side of the binding part  44  and the side guide plate  38  is moved to the jogging position at the side of the side plate, and the binding device of the binding part  44  is operated to bind the stack of the sheet  3  on the tray  34  of the receiving/jogging part  33  (step S 20 ).  
      Thereafter, the discharging mechanism (the arm mechanism of the discharge part  41 , etc.) is operated to discharge the bound stack of the sheet  3  on the tray  34  to the discharge tray (step S 21 ). Specifically, the arm mechanism of the discharge part  41  moves the stopping plate  39  and the end plate  37  toward the end side of the tray  34  opposite the end thereof where the binding part  44  is arranged, so that the stack of the sheet  3  on the tray  34  is moved toward the end side of the tray  34  opposite the end thereof where the binding part  44  is arranged a predetermined distance. Thereafter, when the sensor  40  has detected the existence of the stack of the sheet  3  on the tray  34 , the tray  34  is lowered to the position indicated by the two-dot-dashed line in  FIG. 3 , and the end plate  37  moves to push the stack of the sheet  3  on the tray  34  to the discharge part  41 . Further, when the stack of the sheet  3  has been detected with the sensor  42 , the discharge roller pair  43  starts to rotate, so that the stack of the sheet  3  is discharged to the discharge tray.  
       FIG. 6  illustrates a construction of the binding apparatus  2  according to another embodiment of the present invention.  
      In the binding apparatus  2  of the previous embodiment, as described above, the sheet  3  folded at a single folding portion thereof and the sheet  3  folded at two folding portions thereof are discharged onto the tray  34  of the receiving/jogging part  33  from the end side of the tray  34  opposite the end side thereof where the binding part  44  is arranged. Thereby, the sheet  3  folded at the single folding portion thereof is received on the tray  34  of the receiving/jogging part  33  with the folded single folding portion thereof located at the end side of the tray  34  where the binding part  44  is arranged, so that the sheet  3  folded at the single folding portion thereof is bound by the binding device of the binding part  44  at the edge portion thereof at the folded single folding portion side, and the sheet  3  folded at the two folding portions thereof is received on the tray  34  with the end of the sheet  3  opposite the folded second folding portion thereof located at the end side of the tray  34  where the binding part  44  is arranged, so that the sheet  3  folded at the two folding portions thereof is bound by the binding device of the binding part  44  at the edge portion thereof opposite the folded second folding portion thereof. On the other hand, the binding apparatus  2  of this embodiment is configured such that the sheet  3  folded at a single folding portion thereof and the sheet  3  folded at two folding portions thereof are discharged onto the tray  34  of the receiving/jogging part  33  from the end side of the tray  34  where the binding part  44  is arranged.  
      In the binding apparatus  2  of this embodiment, as illustrated in  FIG. 6 , the second guide part  21  is configured to guide the sheet  3  folded at a single folding portion thereof and conveyed by the second roller pair  14  to be discharged onto the tray  34  of the receiving/jogging part  33  from the end side of the tray  34  where the binding part  44  is arranged. More specifically, the second guide part  21  is configured to guide the sheet  3  folded at the single folding portion thereof to be discharged onto a downstream side portion of the second path  30 . Further, the roller pair  23  fixed in a position is used for the stopping/conveying device stopping and conveying the sheet  3  being conveyed by the second roller pair  14  and guided by the second guide part  21 , and a relaying roller pair  53  is arranged at the end of the second guide part  21  to discharge the sheet  3  onto the downstream side portion of the second path  30 . The sheet  3  folded at the single folding portion thereof, which has been discharged onto the downstream side portion of the second path  30  from the second guide part  21 , is discharged by the discharge roller pair  31  of the second path  30  onto the tray  34  of the receiving/jogging part  33  from the end side of the tray  34  where the binding part  44  is arranged.  
      Further, a discharge path  50  is arranged downstream of the third roller pair  15  to convey the sheet  3  folded at two folding portions thereof and conveyed by the third roller pair  15  to be discharged onto the tray  34  of the receiving/jogging part  33  from the end side of the tray  34  where the binding part  44  is arranged. More specifically, the discharge path  50  includes a relaying roller pair  51  to convey the sheet  3  conveyed by the third roller pair  15  and is configured to guide the sheet  3  conveyed by the third roller pair  15  and the relaying roller pair  51  to be discharged onto an end portion of the second path  30  near the exit thereof. The sheet  3  folded at the two folding portions thereof, which has been discharged onto the end portion of the second path  30  from the discharge path  50 , is discharged by the discharge roller pair  31  of the second path  30  onto the tray  34  of the receiving/jogging part  33  from the end side of the tray  34  where the binding part  44  is arranged.  
      Furthermore, the second guide part  21  is configured to reverse the sheet  3  folded at a single folding portion thereof and conveyed by the second roller pair  14  with the folded single folding portion thereof placed as the leading edge of the sheet  3  to the third roller pair  15  so that the sheet  3  folded at the single folding portion thereof is conveyed by the third roller pair  15  to the discharge path  50  with the end of the sheet  3  opposite the folded single folding portion thereof placed as the leading edge of the sheet  3 . When reversing the sheet  3  folded at the single folding portion thereof to the third roller pair  15 , the roller pair  23  and the relaying roller pair  53  arranged at the end of the second guide part  21  start to rotate in reverse upon detecting the trailing edge of the sheet  3  conveyed by the second roller pair  14  with the sensor  54 , and thereby the sheet  3  is reversed to the third roller pair  15 .  
      In folding the sheet  3  at a single folding portion thereof, when the sheet  3  is folded at the center portion thereof, for example, and the sheet  3  is to be bound at the edge portion of the sheet  3  opposite the folded center portion thereof, the sheet  3  folded at the center portion thereof and conveyed by the second roller pair  14  to the second guide part  21  is conveyed by the roller pair  23  further and is guided by the second guide part  21  to be discharged onto the downstream side portion of the second path  30 . The sheet  3  is then discharged by the discharge roller pair  31  of the second path  30  onto the tray  34  of the receiving/jogging part  33  from the end side of the tray  34  where the binding part  44  is arranged. Thereby, the sheet  3  folded at the center portion thereof is received on the tray  34  with the end of the sheet  3  opposite the folded center portion thereof located at the end side of the tray  34  where the binding part  44  is arranged, so that the sheet  3  is bound by the binding device of the binding part  44  at the edge portion of the sheet  3  opposite the folded center portion thereof.  
      When the sheet  3  folded at the center portion thereof is to be bound at the edge portion of the sheet  3  at the folded center portion side, the sheet  3  is reversed by the second guide part  21  to the third roller pair  15 , and the sheet  3  is conveyed by the third roller pair  15  to the discharge path  50 , so that the sheet  3  is guided by the discharge path  50  to be discharged onto the end portion of the second path  30  and is discharged by the discharge roller pair  31  of the second path  30  onto the tray  34  of the receiving/jogging part  33  from the end side of the tray  34  where the binding part  44  is arranged. Thereby, the sheet  3  folded at the center portion thereof is received on the tray  34  of the receiving/jogging part  33  with the folded center portion thereof located at the end side of the tray  34  where the binding part  44  is arranged, so that the sheet  3  is bound by the binding device of the binding part  44  at the edge portion thereof at the folded center portion side.  
      Further, the binding apparatus  2  of this embodiment is configured such that the sheet  3  conveyed to the folding part  12  is reversed by the first guide part  18  to the second guide part  21  as an unfolded sheet and the sheet  3  is then conveyed by the second guide part  21  further. Thereby, the sheet  3  is received on the tray  34  of the receiving/jogging part  33  as an unfolded sheet with the leading edge and the trailing edge of the sheet  3  when the sheet  3  has been received by the entry part  8  and conveyed to the folding part  12  reversed.  
      When the sheet  3  received by the entry part  4  is to be bound, without being folded, at the edge portion thereof at the trailing edge side of the sheet  3 , the sheet  3  is conveyed to the second path  30 . Thereby, the sheet  3  is received on the tray  34  of the receiving/jogging part  33  with the trailing edge thereof located at the end side of the tray  34  where the binding part  44  is arranged, so that the sheet  3  is bound by the binding device of the binding part  44  at the edge portion thereof at the trailing edge side.  
      When the sheet  3  received by the entry part  4  is to be bound, without being folded, at the edge portion thereof at the leading edge side of the sheet  3 , the sheet  3  is conveyed to the first path  8  and is conveyed to the first guide part  18 . The stopper plate  20  is moved to a reversing position corresponding to the length of the sheet  3  in the direction in which the sheet  3  is conveyed by the entry part  4 , and when the trailing edge of the sheet  3  conveyed by the first roller pair  13  has been detected with the sensor  16 , the stopper plate  20  pushes back the sheet  3  toward the second roller pair  14 , so that the sheet  3  is conveyed by the second roller pair  14  to the second guide part  21  as an unfolded sheet, and the sheet  3  is further conveyed by the roller pair  23  and the relaying roller pair  53  rotating in the arrow direction in  FIG. 6  to be discharged onto the downstream side portion of the second path  30 . The sheet  3  is then discharged by the discharge roller pair  31  of the second path  30  onto the tray  34  of the receiving/jogging part  33  as an unfolded sheet from the end side of the tray  34  where the binding part  44  is arranged. Thereby, the sheet  3  is received on the tray  34  of the receiving/jogging part  33  with the leading edge thereof when the sheet  3  has been received by the entry part  4  located at the end side of the tray  34  where the binding part  44  is arranged, so that the sheet  3  is bound by the binding device of the binding part  44  at the edge portion thereof at the leading edge side when the sheet  3  has been received by the entry part  4 .  
      When folding the sheet  3  conveyed by the entry part  4  at two folding portions thereof, the sheet  3  is folded by the second roller pair  14  at the first folding portion of the two folding portions thereof and by the third roller pair  15  at the second folding portion of the two folding portions thereof as in the previous embodiment, and the sheet  3  folded at the first folding portion and the second folding portion thereof is conveyed by the third roller pair  15  to the discharge path  50 . The sheet  3  is conveyed by the relaying roller pair  51  and is guided by the discharge path  50  to be discharged onto the end portion of the second path  30 . The sheet  3  is then discharged by the discharge roller pair  31  of the second path  30  onto the tray  34  of the receiving/jogging part  33  from the end side of the tray  34  where the binding part  44  is arranged. Thereby, the sheet  3  is received on the tray  34  of the receiving/jogging part  33  with the end of the sheet  3  opposite the folded second folding portion thereof located at the end side of the tray  34  where the binding part  44  is arranged, so that the sheet  3  is bound by the binding device of the binding part  44  at the edge portion thereof opposite the folded second folding portion thereof as in the previous embodiment.  
       FIG. 7A  through  FIG. 7G  illustrates a flowchart of an exemplary operation of the binding apparatus  2  of  FIG. 6 .  
      When the binding apparatus  2  is turned on, the entry roller pair  6  of the entry part  4 , the conveying roller pair  9  and the registration roller pair  11  of the first path  8 , the first roller pair  13 , the second roller pair  14  and the third roller pair  15  of the folding part  12 , and the discharge roller  31  of the second path  30  start to rotate. The switching member  7  of the entry part  4  is moved to the p position in which the sheet  3  conveyed by the entry roller pair  6  is conveyed to the second path  30 , the tray  34  of the receiving/jogging part  33  is moved to the upper position (indicated by a solid line in  FIG. 6 ), and the end plate  37  and the side guide plate  38  of the receiving/jogging part  33  are moved to respective start positions (the most outside positions).  
      When the sheet  3  discharged from the image forming apparatus  1  and put into the opening of the entry part  4  of the binding apparatus  2  is detected with the entry sensor  5  (Yes in step S 31 ), whether the sheet  3  is to be folded and bound or is to be bound, without being folded, is determined according to the instruction received from the image forming apparatus  1  (step S 32 ). When it has been determined in step S 32  that the sheet  3  is to be folded and bound, the switching member  7  is switched to the q position (step S 33 ), so that the sheet  3  is conveyed to the first path  8 .  
      The sheet  3  conveyed to the first path  8  is conveyed by the conveying roller pair  9 , and when the leading edge of the sheet  3  has been detected by the sensor  10  (Yes in step S 34 ), after a predetermined time, the registration roller pair  11  is stopped to be rotated and after a predetermined time, is rotated again (step S 35 ). Thereby, a deviation in the conveying direction of the sheet  3 , such as skewing, is corrected.  
      Thereafter, the sheet  3  is conveyed with the first roller pair  13  to the first guide part  18 . When the leading edge of the sheet  3  has been detected with the sensor  16  (Yes in step S 36 ), whether the sheet  3  is to be folded at a single folding portion (in two-folding) or at two folding portions thereof (in Z-folding) is determined according to the instruction received from the image forming apparatus  1  (step S 37 ).  
      When it has been determined in step S 37  that the sheet  3  is to be folded at two folding portions thereof (in Z-folding), the positions of the two folding portions of the sheet  3  are determined according to the instruction received from the image forming apparatus  1 , and the stopper plate  20  of the first guide part  18  is moved to the position separate from the nip of the first roller pair  13  by the distance corresponding to the length of the sheet  3  from the leading edge to the first folding portion of the two folding portions of the sheet  3 , and the roller pair  23  of the second guide part  21  is rotated in the arrow direction in  FIG. 6  (step S 38 ). Thereby, the sheet  3  being conveyed by the first roller pair  13  is stopped in the timing that the sheet  3  has been conveyed by the first roller pair  13  the distance corresponding to the length of the sheet  3  from the leading edge to the first folding portion of the two folding portions of the sheet  3 , so that the sheet  3  is folded by the second roller pair  14  at the first folding portion thereof, and the sheet  3  is conveyed to the second guide part  21 . The roller pair  23  is stopped to be rotated in the timing that the sheet  3  has been conveyed by the second roller pair  14  the distance corresponding to the length of the sheet  3  from the first folding portion to the second folding portion of the sheet  3  (step S 39 ), so that the sheet  3  being conveyed by the second roller pair  14  is stopped in the timing that the sheet  3  has been conveyed by the second roller pair  14  by the distance corresponding to the length of the sheet  3  from the first folding portion to the second folding portion of the sheet  3 , the sheet  3  is thereby folded by the third roller pair  15  at the second folding portion thereof and is conveyed by the third roller pair  15  to the discharge path  50 .  
      When the trailing edge of the sheet  3  has been detected with the sensor  32  (Yes in step S 40 ), the sheet jogging mechanism (the end plate  37 , etc.) of the receiving/jogging part  33  is operated (step S 41 ).  
      When it has been determined in step S 37  that the sheet  3  is to be folded at a single folding portion thereof (in two-folding), whether the sheet  3  folded at the single folding portion thereof is to be bound at the edge portion thereof at the folded single folding portion side or at the edge portion thereof opposite the folded single folding portion is determined (step S 42 ). When it has been determined in step S 42  that the sheet  3  folded at the single folding portion thereof is to be bound at the edge portion thereof opposite the folded single folding portion, the position of the single folding portion of the sheet  3  is determined according to the instruction received from the image forming apparatus  1 , the stopper plate  20  of the first guide part  18  is moved to the position separate from the nip of the first roller pair  13  by the distance corresponding to the length of the sheet  3  from the leading edge to the single folding portion of the sheet  3 , and the roller pair  23  arranged in the second guide part  21  and the relaying roller pair  53  arranged at the end of the second guide part  21  are rotated in the arrow directions in  FIG. 6  (step S 43 ). Thereby, the sheet  3  being conveyed by the first roller pair  13  is stopped by the stopper plate  20  in the timing that the sheet  3  has been conveyed by the first roller pair  13  by the distance corresponding to the length of the sheet  3  from the leading edge to the single folding portion of the sheet  3 , so that the sheet  3  is fold by the second roller pair  14  at the single folding portion thereof and is conveyed by the second roller pair  14  to the second guide part  21 , and thereafter, the sheet  3  is conveyed further by the roller pair  23  and the relaying roller pair  53  rotating in the arrow directions in  FIG. 6 , respectively, and is guided by the second guide part  21  to be discharged onto the downstream side portion of the second path  30 , and the sheet  3  is then discharged onto the tray  34  of the receiving/jogging part  33 . When the trailing edge of the sheet  3  has been detected with the sensor  32  (Yes in step S 44 ), the jogging mechanism of the receiving/jogging part  33  is operated (step S 41 ).  
      When it has been determined in step S 42  that the sheet  3  folded at the single folding portion thereof is to be bound at the edge portion thereof at the folded single folding portion side, the position of the single folding portion of the sheet  3  is determined according to the instruction received from the image forming apparatus  1 , the stopper plate  20  of the first guide part  18  is moved to the position separate from the nip of the first roller pair  13  by the distance corresponding to the length of the sheet  3  from the leading edge to the single folding portion of the sheet  3 , and the roller pair  23  arranged in the second guide part  21  and the relaying roller pair  53  arranged at the end of the second guide part  21  are rotated in the arrow directions in  FIG. 6  (step S 45 ). Thereby, the sheet  3  being conveyed by the first roller pair  13  is stopped by the stopper plate  20  in the timing that the sheet  3  has been conveyed by the first roller pair  13  by the distance corresponding to the length of the sheet  3  from the leading edge to the single folding portion of the sheet  3 , so that the sheet  3  is fold by the second roller pair  14  at the single folding portion thereof and is conveyed by the second roller pair  14  to the second guide part  21 , and the sheet  3  is further conveyed by the roller pair  23  and the relaying roller pair  53  of the second guide part  21 . The roller pair  23  and the relaying roller pair  53  start to rotate in reverse upon detecting the trailing edge of the sheet  3  conveyed by the second roller pair  14  with the sensor  54  (step S 46 ), so that the sheet  3  is reversed to the third roller pair  15  and is conveyed by the third roller pair  15  to the discharge path  50 , and thereafter, the sheet  3  is discharged onto the end portion of the second path  30  and is then discharged onto the tray  34  of the receiving/jogging part  33 . When the trailing edge of the sheet  3  has been detected with the sensor  32  (Yes in step S 47 ), the jogging mechanism of the receiving/jogging part  33  is operated (step S 41 ).  
      When it has been determined in step S 32  that the sheet  3  is to be bound, without being folded, whether the sheet  3  is to be bound at the edge portion thereof at the leading edge side or at the trailing edge side is determined (step S 48 ). When it has been determined in step S 48  that the sheet  3  is to be bound at the edge portion at the trailing edge side, the switching member  7  is switched to the p position (step S 49 ), so that the sheet  3  is conveyed to the second path  30 . The sheet  3  is conveyed with the discharge roller pair  31  and is discharged onto the tray  34  of the receiving/jogging part  33  as an unfolded sheet. When the trailing edge of the sheet  3  has been detected with the sensor  32  (Yes in step S 50 ), the jogging mechanism of the receiving/jogging  33  is operated (step S 41 ).  
      When it has been determined in step S 48  that the sheet  3  is to be bound at the edge portion thereof at the trailing edge side, the switching member  7  is switched to the q position (step S 51 ), so that the sheet  3  is conveyed to the second path  30 . The stopper plate  20  is moved to a reversing position corresponding to the length of the sheet  3  in the direction in which the sheet  3  is conveyed by the entry part  4  and the roller pair  23  and the relaying roller pair  53  start to rotate in the arrow directions in  FIG. 6  (step S 52 ). When the trailing edge of the sheet  3  conveyed by the first roller pair  13  has been detected with the sensor  16 , the stopper plate  20  pushes back the sheet  3  toward the second roller pair  14  (step S 53 ), so that the sheet  3  is conveyed by the second roller pair  14  to the second guide part  21  as an unfolded sheet, and the sheet  3  is conveyed by the roller pair  23  and the relaying roller pair  53  to be discharged onto the downstream side portion of the second path  30 , and thereafter, the sheet  3  is discharged onto the tray  34  of the receiving/jogging part  33 . When the trailing edge of the sheet  3  has been detected with the sensor  32  (Yes in step S 54 ), the jogging mechanism of the receiving/jogging  33  is operated (step S 41 ).  
      The sheet  3  discharged onto the tray  34  of the receiving/jogging part  33  from the discharge path  50 , the second guide part  21 , or the second path  30  is aligned with the stopping plate  39  by the reciprocating movement of the end plate  37  of the receiving/jogging part  33  against the stopping plate  39  and with the side plate of the receiving/jogging part  33  at the rear side of the tray  34  in the widthwise direction of the tray  34  by the reciprocating movement of the side guide plate  38  against the side plate.  
      Thereafter, it is determined if the sheet  3  is the last sheet to be bound or if a predetermined number of the sheet  3  has been discharged onto the tray  34  of the receiving/jogging part  33  according to the instruction received from the image forming apparatus  1  (step S 55 ). When it has been determined that the sheet  3  is the last sheet to be bound or the predetermined number of the sheet  3  has been discharged onto the tray  34  of the receiving/jogging part  33  (Yes in step S 55 ), the end plate  37  is move to the jogging position at the side of the binding part  44  and the side guide plate  38  is moved to the jogging position at the side of the side plate, and the binding device of the binding part  44  is operated to bind the stack of the sheet  3  on the tray  34  of the receiving/jogging part  33  (step S 56 ).  
      Then, the discharging mechanism (the arm mechanism of the discharge part  41 , etc.) of the discharge part  41  is operated to discharge the bound stack of the sheet  3  on the tray  34  to the discharge tray (step S 57 ). Specifically, the arm mechanism of the discharge part  41  moves the stopping plate  39  of the binding part  44  and the end plate  37  of the receiving/jogging part  33  toward the end side of the tray  34  opposite the end side thereof where the binding part  44  is arranged, so that the stack of the sheet  3  on the tray  34  is moved toward the end side of the tray  34  opposite the end side thereof where the binding part  44  is arranged a predetermined distance. Thereafter, when the sensor  40  has detected the existence of the stack of the sheet  3  on the tray  34 , the tray  34  is lowered to the position indicated by the two-dot-dashed line in  FIG. 6 , and the end plate  37  moves to push the stack of the sheet  3  on the tray  34  to the discharge part  41 . Further, when the stack of the sheet  3  has been detected with the sensor  42 , the discharge roller pair  43  starts to rotate, so that the stack of the sheet  3  is discharged to the discharge tray.  
      Numerous additional modifications and variations of the present invention are possible in light of the above-teachings. It is therefore to be understood that within the scope of the claims, the present invention can be practiced otherwise than as specifically described herein.