Patent Publication Number: US-8540228-B2

Title: Sheet processing device and image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2010-163384 filed Jul. 20, 2010. 
     BACKGROUND 
     (i) Technical Field 
     The present invention relates to a sheet processing device and an image forming apparatus. 
     SUMMARY 
     According to an aspect of the present invention, there is provided a sheet processing device including a stacking unit that is used to stack a bundle of sheets that are placed upon each other with first edge portions of the sheets being aligned with each other; a first binding unit that binds the first edge portions of the bundle of sheets stacked upon the stacking unit; a second binding unit that is provided integrally with the first binding unit in a direction along the first edge portions of the bundle of sheets stacked upon the stacking unit, the second binding unit binding the first edge portions by a binding method differing from a binding method of the first binding unit; and an angle changing mechanism that is capable of changing an angle of the first binding unit with respect to the bundle of sheets when binding the first edge portions with the first binding unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a schematic structural view of an image forming system to which an exemplary embodiment of the present invention is applied; 
         FIG. 2  is a schematic structural view of the vicinity of a compiling stacking section; 
         FIG. 3  is a schematic structural view of the vicinity of the compiling stacking section as viewed from the direction of arrow III shown in  FIG. 2 ; 
         FIGS. 4A to 4C  illustrate the relationships between an end guide and a sheet; 
         FIG. 5  illustrates the structure of a binding device; 
         FIGS. 6A to 6D  illustrate the structure of a stapleless binding mechanism and a portion to which a stapleless binding operation is performed; 
         FIGS. 7A and 7B  are schematic structural views showing portions where binding operations are performed by a stapler and the stapleless binding mechanism, respectively; 
         FIGS. 8A and 8B  each illustrate the relationship between the position of a first edge portion Sa of a sheet S and the position of an image formed on the sheet S; 
         FIGS. 9A and 9B  each illustrate the relationship between the position of a binding portion and the position of the image formed on the sheet; 
         FIG. 10  is a side view of the vicinity of an end guide according to another mode; and 
         FIGS. 11A and 11B  illustrate a bundle of sheets on which a stapleless binding operation is performed in another exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments of the present invention will hereunder be described in detail with reference to the attached drawings. 
     Image Forming System  1   
       FIG. 1  is a schematic structural view of an image forming system  1  to which an exemplary embodiment of the present invention is applied. The image forming system  1  shown in  FIG. 1  includes an image forming device  2 , such as a printer or a copying machine, that forms images by electrophotography, and a sheet processing device  3  that performs a postprocessing operation on a sheet S on which, for example, a toner image is formed by the image forming device  2 . 
     Image Forming Device  2   
     The image forming device  2  includes a sheet supplying section  6 , an image forming section  5 , a sheet reversing device  7 , and discharge rollers  9 . The sheet supplying section  6  supplies sheets S on which images are to be formed. The image forming section  5  forms the images on the sheets S supplied from the sheet supplying section  6 . The sheet reversing device  7  reverses the surfaces of the sheets S on which the images are formed by the image forming section  5 . The discharge rollers  9  discharge the sheets S on which the images are formed. The image forming device  2  also includes a user interface  90  that receives information regarding a binding operation from a user. 
     Here, the image forming section  5  serving as an exemplary image forming unit is formed so that the position where an image is to be formed on the sheet S is capable of being changed. That is, it is possible to change the distance from an edge portion of the sheet S to the image to be formed. 
     The sheet supplying section  6  includes a first sheet supplying loading section  61  and a second sheet supplying loading section  62 , which have the sheets S loaded in the interiors thereof and which supply the sheets S to the image forming section  5 . The sheet supplying section  6  also includes a first sheet supplying sensor  63  and a second sheet supplying sensor  64 . The first sheet supplying sensor  63  detects whether or not there are any sheets S in the first sheet supplying loading section  61 . The second sheet supplying sensor  64  detects whether or not there are any sheet S in the second sheet supplying loading section  62 . 
     Sheet Processing Device  3   
     The sheet processing device  3  includes a transporting device  10  and a postprocessing device  30 . The transporting device  10  transports the sheets S output from the image forming device  2  further downstream. The postprocessing device  30  includes, for example, a compiling stacking section  35  that gathers the sheets S and forms a bundle of sheets S, and a binding device  40  that binds edge portions of the sheets S. The sheet processing device  3  also includes a controller  80  that controls the entire image forming system  1 . 
     The transporting device  10  of the sheet processing device  3  includes a pair of entrance rollers  11  and a puncher  12 . The entrance rollers  11  receive the sheets S output through the discharge rollers  9  of the image forming device  2 . The puncher  12  punches out holes in the sheets S received from the entrance rollers  11  if necessary. The transporting device  10  also includes a pair of first transporting rollers  13  that transport the sheets S further downstream from the puncher  12 , and a pair of second transporting rollers  14  that transport the sheets S towards the postprocessing device  30 . 
     The postprocessing device  30  of the sheet processing device  3  includes a pair of receiving rollers  31  that receive the sheets S from the transporting device  10 . The postprocessing device  30  also includes the compiling stacking section  35  and a pair of exit rollers  34 . The compiling stacking section  35  is provided downstream from the receiving rollers  31 , and gathers and holds the sheets S. The exit rollers  34  discharge the sheets S towards the compiling stacking section  35 . 
     The postprocessing device  30  further includes paddles  37  that rotate so as to push the sheets S to an end guide  35   b  (described later) of the compiling stacking section  35 . Still further, the postprocessing device  30  includes tampers  38  for aligning the edge portions of the sheets S. Still further, the postprocessing device  30  includes eject rollers  39  which hold the sheets S gathered and stacked at the compiling stacking section  35  and which rotate to transport the bound bundle of sheets S downstream. 
     Still further, the postprocessing device  30  includes the binding device  40  that binds the edge portions of the bundle of sheets S gathered and stacked at the compiling stacking section  35 . The postprocessing device  30  has an opening  69  used for discharging the bundle of sheets S to the outside of the postprocessing device  30  by the eject rollers  39 . The postprocessing device  30  also has a stacking section  70  for stacking the bundle of sheets S discharged from the opening  69  so as to allow a user to easily take the bundle of sheets S. 
     Structure of Vicinity of Binding Unit 
     Next, with reference to  FIGS. 2 to 4C , the compiling stacking section  35 , and the binding device  40 , etc., provided in the vicinity of the compiling stacking section  35 , will be described. Here,  FIG. 2  is a schematic structural view of the vicinity of the compiling stacking section  35 , and  FIG. 3  is a schematic structural view of the vicinity of the compiling stacking section  35  as viewed from the direction of arrow III shown in  FIG. 2 .  FIGS. 4A to 4C  illustrate the relationships between the end guide  35   b  and a sheet S.  FIG. 4A  illustrates the operation of the end guide  35   b .  FIG. 4B  is a schematic view of the position of a binding portion when the end guide  35   b  is at a side where it is close to the sheet S.  FIG. 4C  is a schematic view of the position of the binding portion when the end guide  35   b  is at a side where it is further away from the sheet S. 
     In  FIG. 2 , for simplification, some of the members, such as an end guide spring  35   c , are not shown. The lower side of  FIG. 3  is a user side of the image forming system  1 , that is, a near side in the plane of  FIGS. 1 and 2 . 
     The compiling stacking section  35 , serving as an exemplary stacking unit, has a bottom portion  35   a  having an upper side on which the sheets S are stacked. 
     The bottom portion  35   a  is tilted so that the sheets S fall along the upper side thereof. In addition, the compiling stacking section  35  has the end guide  35   b  disposed so that the front edge portions in a sheet travelling direction of the sheets S that fall along the bottom portion  35   a  are aligned. 
     Although described in detail later, the sheets S at the vicinity of the compiling stacking section  35  are first supplied towards the compiling stacking section  35  (refer to a first traveling direction S 1  in  FIG. 2 ), and then, the traveling direction is reversed so that the sheets S drop along the bottom portion  35   a  of the compiling stacking section  35  (refer to a second traveling direction S 2  in  FIG. 2 ). Thereafter, the edge portions of the sheets S are aligned to form a bundle of sheets S. Then, the traveling direction is reversed so that the bundle of sheets S moves upward along the bottom portion  35   a  of the compiling stacking section  35  (refer to a third traveling direction S 3  in  FIG. 2 ). 
     Here, as shown in  FIG. 3 , in the exemplary embodiment, each edge portion of the bottom portion  35   a  of the compiling stacking section  35  is defined as follows. First, the edge portion at the front side in the second traveling direction S 2  of the bottom portion  35   a  (indicating the direction in which the sheets S fall along the upper side of the bottom portion  35   a  of the compiling stacking section  35 ) is called a front-side edge portion Ta. Next, the edge portion extending in the second traveling direction S 2  and disposed at the user side (that is, the lower side in  FIG. 3 ) of the image forming system  1  is called a side edge portion Tb. A portion that is provided between the front-side edge portion Ta and the side edge portion Tb is called a corner Te. 
     As shown in  FIGS. 4B to 4C , in the exemplary embodiment, respective portions of the sheets S disposed on the bottom portion  35   a  of the compiling stacking section  35  are defined as follows. First, the edge portion of each sheet S extending along the front-side edge portion Ta and contacting the end guide  35   b  is called a first edge portion Sa. The edge portion intersecting the first edge portion Sa and extending along the side edge portion Tb is called a second edge portion Sb. Further, a portion of each sheet S provided between the first edge portion Sa and the second edge portion Sb is called a corner Se. 
     Further, as shown in  FIGS. 4B and 4C , in the exemplary embodiment, an edge of an image (formed on the sheet S) at the side of the first edge portion Sa is called an image edge Ia. 
     As shown in  FIG. 4A , the end guide  35   b  is provided so as to be capable of moving towards and away from the bottom portion  35   a  of the compiling stacking section  35  (refer to arrows D 1  and D 2 ). More specifically, the end guide  35   b  has the following structure. 
     First, in the up-down direction in  FIG. 3 , the end guide  35   b  is longer than the bottom portion  35   a  of the compiling stacking section  35 . In addition, a pair of end guide springs  35   c  and a pair of solenoids  35   d  are connected, one end guide spring  35   c  and one solenoid  35   d  being connected to one end of the end guide  35   b , and the other end guide spring  35   c  and the other solenoid  35   d  being connected to the other end of the end guide  35   b . The end guide springs  35   c  and the solenoids  35   d  are disposed at the same side of the end guide  35   b  (that is, at the right side of the end guide  35   b  in  FIG. 3 ). The end guide springs  35   c  are compressed, and are disposed so as to push the end guide  35   b  (refer to the arrows D 2 ). Shafts of the solenoids  35   d  are capable of being extended, with one end of each shaft being connected to the end guide  35   b.    
     Here, as shown in  FIG. 4A , the end guide  35   b  is movable between a position Pex where the end guide  35   b  is close to the bottom portion  35   a  and a position Pey where the end guide  35   b  is further away from the bottom portion  35   a . The distance between the positions Pex and Pey is d 0 . 
     When the solenoids  35   d  are not operating, the end guide  35   b  is pushed by the compressed end guide springs  35   c , and disposed at the position Pey that is further away from the bottom portion  35   a . In contrast, when the solenoids  35   d  are operating, the solenoids  35   d  cause the end guide  35   b  to move towards the bottom portion  35   a , so that the end guide  35   b  is disposed at the position Pex that is close to the bottom portion  35   a.    
     Here, moving of the position of a binding portion of a sheet by moving of the end guide  35   b  will be described. 
     First, the case in which the end guide  35   b  is disposed at the position Pex will be described. The end guide  35   b  is disposed at the position Pex. Then, a sheet S is supplied to the bottom portion  35   a  of the compiling stacking section  35  and is disposed so that the first edge portion Sa of the sheet S contacts the end guide  35   b . When, in this state, a binding operation is performed, the distance from the first edge portion Sa to a portion where the binding operation is performed is reduced. In contrast, when the end guide  35   b  is disposed at the position Pey, if the sheet is disposed at the bottom portion  35   a  of the compiling stacking section  35  and is subjected to the binding operation, the distance from the first edge portion Sa to a portion where the binding operation is performed is increased. This is described in more detail below. 
     That is, if the stapleless binding mechanism  50  performs the binding operation when the end guide  35   b  is disposed at the position Pex, the distance from an edge of the binding portion situated away from the first edge portion Sa to the first edge portion Sa becomes a distance d 1  (see  FIG. 4B ). In contrast, if the stapleless binding mechanism  50  performs the binding operation when the end guide  35   b  is disposed at the position Pey, the distance from the edge of the binding portion situated away from the first edge portion Sa to the first edge portion Sa becomes a distance d 2  (see  FIG. 4C ). The distance d 2  is longer than the distance d 1  by, for example, approximately 3 to 5 mm. 
     Although, in  FIGS. 4A to 4C , the case in which the stapleless binding mechanism  50  performs the binding operation (in which a stapleless binding portion  51  is disposed (described in detail later)) is described, a stapler  45  may be used to perform a binding operation (in which a staple  41  is disposed (described later)). That is, the end guide  35   b  is formed so that the distance from the first edge Sa of a sheet S to a binding portion is capable of being changed even if the binding operation is performed by either one of the stapleless binding mechanism  50  and the stapler  45 . 
     Each member of the image forming system  1  will be described again. The paddles  37  are provided above the compiling stacking section  35 , and downstream in the first traveling direction S 1  of the sheet S from the exit rollers  34 . The paddles  37  are provided so that their distance from the bottom portion  35   a  of the compiling stacking section  35  changes when the paddles  37  are driven by, for example, a motor (not shown). More specifically, the paddles  37  are provided so as to be movable in the direction of arrow U 1  and the direction of arrow U 2  in  FIG. 2 . The paddles  37  move in the direction of arrow U 1  to move towards the bottom portion  35   a  of the compiling stacking section  35  (that is, move to a position Pb indicated by a solid line). The paddles  37  move in the direction of arrow U 2  to move away from the bottom portion  35   a  of the compiling stacking section  35  (that is, move to a position Pa indicated by broken lines). The paddles  37  rotate in the direction of arrow R in  FIG. 2 , so that the sheet S transported along the first traveling direction S 1  in  FIG. 2  is pushed in the second traveling direction S 2  at the compiling stacking section  35 . 
     The tampers  38  (see  FIG. 1 ) include a first tamper  38   a  and a second tamper  38   b  opposing each other with the compiling stacking section  35  being disposed therebetween. More specifically, the first tamper  38   a  and the second tamper  38   b  are disposed so as to oppose each other in a direction intersecting the second traveling direction S 2  (that is, the up-down direction in  FIG. 3 ). The first tamper  38   a  and the second tamper  38   b  are provided so that the distance between the first tamper  38   a  and the second tamper  38   b  changes when driving force of, for example, a motor (not shown) is applied thereto. 
     Here, the tampers  38  are formed so that the edge portions extending along the traveling direction of the sheets S that fall along the bottom portion  35   a  are aligned. More specifically, the first tamper  38   a  is disposed so as to move in the directions of arrows C 3  and C 4  between a position where the first tamper  38   a  is close to the compiling stacking section  35  (that is, a position Pax indicated by a solid line) and a position where the first tamper  38   a  is further away from the compiling stacking section  35  (that is, a position Pay indicated by broken lines). The second tamper  38   b  is disposed so as to move in the directions of arrows C 3  and C 4  between a position where the second tamper  38   b  is close to the compiling stacking section  35  (that is, a position Pbx indicated by a solid line) and a position where the second tamper  38   b  is further away from the compiling stacking section  35  (that is, a position Pby indicated by broken lines). 
     The positions Pax and Pay of the first tamper  38   a  and the positions Pbx and Pby of the second tamper  38   b  in the exemplary embodiment are capable of being changed in accordance with the size and orientation of the sheets S supplied to the compiling stacking section  35 . 
     The eject rollers  39  include a first eject roller  39   a  and a second eject roller  39   b . The first eject roller  39   a  and the second eject roller  39   b  are disposed above and below the bottom portion  35   a  so as to oppose each other with the bottom portion  35   a  of the compiling stacking section  35  being disposed therebetween. 
     In addition, the first eject roller  39   a  is provided at a side of the bottom portion  35   a  of the compiling stacking section  35  where the sheets S are stacked. The first eject roller  39   a  is provided so as to be capable of moving towards and away from the second eject roller  39   b  when a driving force of, for example, a motor (not shown) is applied. That is, the distance between the first eject roller  39   a  and the sheets S that are stacked upon the bottom portion  35   a  of the compiling stacking section  35  is changeable. In contrast, the second eject roller  39   b  is disposed at a side of the bottom portion  35   a  of the compiling stacking section  35  that is below the side where the sheets S are stacked. The position of the second eject roller  39   b  is fixed. The second eject roller  39   b  only rotates. 
     More specifically, the first eject roller  39   a  moves in the direction of arrow Q 1  to move towards the bottom portion  35   a  of the compiling stacking section  35  (a position P 2  indicated by broken lines). In contrast, the first eject roller  39   a  moves in the direction of arrow Q 2  to move away from the bottom portion  35   a  of the compiling stacking section  35  (a position P 1  indicated by a solid line). 
     The first eject roller  39   a  receives a driving force of, for example, a motor (not shown) while it contacts the sheets S, and rotates in the direction of arrow T 1 , so that a bundle of sheets S moves upward (in the third traveling direction S 3 ) and is transported. 
     The positions P 1  and P 2  of the first eject roller  39   a  are changeable in accordance with the number of and thickness of the sheets S that are supplied to the compiling stacking section  35 . 
     Binding Device  40   
     Next, the binding device  40  will be described with reference to  FIGS. 3 and 6A  to  6 D. Here,  FIG. 5  illustrates the structure of the binding device  40 .  FIGS. 6A to 6D  illustrate the structure of the stapleless binding mechanism  50  and a portion to which a stapleless binding operation is performed.  FIG. 6A  illustrates the structure of the stapleless binding mechanism  50 .  FIG. 6B  illustrates a slit  521  and a flap  522  formed in a sheet S.  FIG. 6C  illustrates an operation in which the flap  522  is inserted into the slit  521 .  FIG. 6D  illustrates the portion where a binding operation is performed by the stapleless binding mechanism  50 . 
     The binding device  40  includes the stapler  45 , serving as an exemplary first binding unit and as an exemplary staple binding unit, and the stapleless binding mechanism  50  serving as an exemplary second binding unit and an exemplary sheet binding unit. The stapler  45  is formed so that, by pushing staples  41  (described below) one by one into the sheets S, the edge portions of the bundle of sheets S held by the compiling stacking section  35  are bound. The stapleless binding mechanism  50  is formed so that the edge portions of the bundle of sheets S held by the compiling stacking section  35  are bound by processing portions of the sheets S without using the staples  41 . The stapler  45  and the stapleless binding mechanism  50  are connected to each other through a joint  48 , and are continuously provided along the front-side edge portion Ta. 
     The stapler  45  is disposed closer to the user side (that is, the lower side in  FIG. 3 ) of the image forming system  1  than the stapleless binding mechanism  50 . When the stapler  45  is disposed closer to the user side (that is, the lower side in  FIG. 3 ), it is possible to easily perform maintenance on the stapler  45 , such as replenishing the stapler  45  with the staples  41 . 
     Here, whereas the stapler  45  uses the staples  41 , the stapleless binding mechanism  50  does not use members that need to be replenished, such as the staples  41 . The stapler  45  is more frequently maintained than the stapleless binding mechanism  50 . Therefore, the stapler  45  is capable of being more easily maintained. 
     The binding device  40  is disposed on a rail  44  so as to be movable along the front-side edge portion Ta by a motor (not shown) (refer to a double-headed arrow A in  FIG. 3 ). In addition, the stapler  45  and the stapleless binding mechanism are capable of binding any position at the side of the front-side edge portion Ta of the bottom portion  35   a.    
     Stapler  45   
     The stapler  45  is formed so as to perform binding at the corner Te of the bottom portion  35   a  in addition to at the side of the front-side edge portion Ta of the bottom portion  35   a . The stapler  45  differs on this point from the stapleless binding mechanism  50  that performs binding only at the side of the front-side edge portion Ta of the bottom portion  35   a.    
     More specifically, the stapler  45  has the following structure. 
     The stapler  45  has a rotational shaft  47  adjacent to the stapleless binding mechanism  50  and at the side of the front-side edge portion Ta. The rotational shaft  47  is connected to a motor (not shown). 
     When a motor (not shown), serving as an exemplary angle changing mechanism, is driven, the stapler  45  is rotatable around the rotational shaft  47  (refer to arrow B). That is, the stapler  45  has a rotating structure. Here, the stapler  45  is capable of rotating independently of the stapleless binding mechanism  50  with the connection between the stapler  45  and the stapleless binding mechanism  50  through the joint  48  being maintained. The rotation of the stapler  45  does not move the stapleless binding mechanism  50 . 
     The stapler  45  is formed so that, by pushing the staples  41  (described below) one by one into the sheets S, the edge portions of the bundle of sheets S held by the compiling stacking section  35  are bound. That is, a stapler motor (not shown) is driven, and the stapler  45  pushes one staple  41  (described later) into the bundle of sheets S. When the staple  41  is pushed into the bundle of sheets S, and the ends of the staples  41  are bent at the opposite side of the bundle of sheets S, the bundle of sheets S is bound. With the pushed-in staple  41  being tilted with respect to the first edge portions Sa of the sheets S, the staple  41  is disposed in the corners Se of the sheets S. 
     Stapleless Binding Mechanism  50   
     The stapleless binding mechanism  50  is formed so that the edge portions of the bundle of sheets S held by the compiling stacking section  35  are bound without using the staples  41  (discussed later). More specifically, the stapleless binding mechanism  50  has the following structure. 
     The stapleless binding mechanism  50  has a base  501  and a base section  503  disposed opposite each other. As shown in  FIG. 6A , the stapleless binding mechanism  50  is formed so that, when the base section  503  moves towards the base section  501  (in the direction of an illustrated arrow F 1 ) while a bundle of sheets S is interposed at the base  501 , the bundle of sheets S is capable of being bound. 
     A bottom member  502  is disposed parallel to the base  501  so that the sheets S are interposed between the base  501  and the bottom member  502 . The base  501  is provided with a protrusion  506  extending towards the base section  503  and formed integrally with the base  501 . 
     The base section  503  is provided with a blade  504  and a punching member  505 . The blade  504  forms a cut in the bundle of sheets S. The punching member  505  forms and bends the flap  522  (described later) in the bundle of sheets S, and inserts the flap  522  into the cut formed by the blade  504 . 
     The blade  504  is a substantially rectangular plate-like member that extends towards the bundle of sheets S interposed between the base  501  and the bottom member  502 . More specifically, the blade  504  has an eyelet  504   a  and a tip  504   b . The eyelet  504   a  is formed in a substantially rectangular surface of the blade  504 . The width of the tip  504   b  becomes smaller as the tip  504   b  extends towards the sheets S. 
     The punching member  505  has an L-shaped bent portion. One end portion of the punching member  505  corresponds to a principle portion  505   a , and the other end portion corresponds to an auxiliary portion  505   b.    
     The punching member  505  has a principle-portion rotational shaft  505   r  provided at the L-shaped bent portion. The punching member  505  is rotatable around the principle-portion rotational shaft  505   r . More specifically, the principle portion  505   a  is tiltable towards the blade  504 . A gap is formed between the auxiliary portion  505   b  and the base section  503  so as to allow the punching member  505  to rotate. 
     Here, the principle portion  505   a  extends towards the base section  501 . The principle portion  505   a  has a cutter portion  505   c  at a side opposite to the side where the principle-portion rotational shaft  505   r  is provided, that is, at a side opposing the base  501 . The cutter portion  505   c  includes a cutting edge that punches out the shape of the flap  522 . The cutter portion  505   c  does not have a cutting edge at a side opposing the blade  504 . That is, the cutter portion  505   c  is formed so that the flap  522  and the sheets S are continuously provided at an end portion  522   a  (described later). Further, the principle portion  505   a  is provided with a protrusion  505   d  extending towards the blade  504  at a side portion of the principle portion  505   a , more specifically, at the side opposing the blade  504 . 
     A binding operation of the stapleless binding mechanism  50  is as follows. 
     That is, a stapleless binding motor (not shown) is driven to cause the base section  503  to move towards the base section  501 , so that the tip  504   b  of the blade  504  and the cutter portion  505   c  of the punching member  505  are driven through a bundle of sheets S. As shown in  FIG. 6B , the slit  521  (serving as an exemplary cut) and the flap  522  (serving as an exemplary partially punched sheet piece) are formed in the bundle of sheets S through which the tip  504   b  and the cutter portion  505   c  are driven. The flap  522  is formed by punching a portion of the bundle of sheets S with the end portion  522   a  kept attached to the bundle of sheets S. 
     When the base section  503  is further pushed, the auxiliary portion  505   b  of the punching member  505  strikes the protrusion  506  integrally formed with the base  501 , so that the punching member  505  rotates clockwise around the principle-portion rotational shaft  505   r  in  FIG. 6A . By this, the principle portion  505   a  is tilted towards the blade  504 , and the protrusion  505   d  of the punching member  505  moves towards the blade  504 . Then, as shown in  FIG. 6C , the protrusion  505   d  of the punching member  505  bends the flap  522 , and pushes the flap  522  towards and into the eyelet  504   a  of the blade  504  in the illustrated direction of arrow F 2 . In  FIG. 6C , the punching member  505  is not shown. 
     In this state, the base section  503  is moved away from the base  501 . That is, when the base section  503  is raised in the illustrated direction of arrow F 3 , the flap  522  is raised with the flap  522  being caught in the eyelet  504   a  of the blade  504 . Then, as shown in  FIG. 6D , the flap  522  is inserted into the slit  521 , to bind the bundle of sheets S. At this time, a binding hole  523  is formed in the bundle of sheets S where the flap  522  is punched from the bundle of sheets S. 
     Comparison of Binding Portions 
     Next, with reference to  FIGS. 7A and 7B , portions that are bound by the stapler  45  and the stapleless binding mechanism  50  will be described. Here,  FIGS. 7A and 7B  are schematic structural views showing portions where binding operations are performed by the stapler  45  and the stapleless binding mechanism  50 . 
     First, a staple  41  is disposed in a portion that is to be bound by the stapler  45 . In contrast, a stapleless binding portion  51  is formed in a portion to be bound by the stapleless binding mechanism  50 . 
     The staple  41  and the stapleless binding portion  51  are disposed so that they do not overlap images to be formed on the sheets S. This is for preventing the images that are formed from becoming invisible. 
     A widthwise-direction length of the stapleless binding portion  51  (that is, a length L 2 X) is longer than a widthwise-direction length of the staple  41  (that is, a length L 1 X). A longitudinal-direction length of the stapleless binding portion  51  (that is, a length L 2 Y) is longer than a longitudinal-direction length of the staple  41  (that is, a length L 1 Y). Therefore, the area of the stapleless binding portion  51  is also larger than the area of the staple  41 . 
     In the exemplary embodiment, the staple  41  is used for the binding operation at the corner Te of the bottom portion  35   a  because the longitudinal-direction length of the staple  41  is shorter than that of the stapleless binding portion  51 . If the stapleless binding portion  51  having the longer longitudinal-direction length is disposed obliquely with respect to the corner Te of the bottom portion  35   a , the stapleless binding portion  51  is disposed towards the central portion of the sheet S. Therefore, the possibility with which the binding portion  51  overlaps the image formed on the sheet S is increased. 
     Further, the stapleless binding portion  51  includes the binding hole  523  formed by punching the flap  522 . As a result, a portion extending from the binding hole  523  to the first edge portion Sa of each sheet S tends to be torn. In particular, when other members are passed through the binding hole  523  (formed in the sheets S) for filing, the sheets S tend to become torn. Therefore, in order to prevent the sheets S from becoming torn, it is necessary for the stapleless binding portion  51  to be disposed at a certain distance from the first edge portion Sa of each sheet S. 
     In other words, it is necessary for the stapleless binding portion  51  to have a wider binding margin than the staple  41 . Here, the term “binding margin” refers to an edge portion of a sheet S where an image is not formed. For example, the binding margin of the sheet S close to the first edge portion Sa refers to a portion of the sheet S extending to the first edge portion Sa from an image edge Ia situated at the side of the first edge portion Sa of the sheet S. 
     In order to prevent tearing of the sheet S, a required distance from the stapleless binding portion  51  to the first edge portion Sa of the sheet S is changed depending upon the number of sheets S to be bound and the strengths of the materials of the sheets S to be bound. 
     Operation of Image Forming System  1   
     Next, the operation of the image forming system  1  will be described with reference to  FIGS. 1 to 4C . Here, the case in which the stapler  45  of the binding device  40  performs a binding operation at the front-side edge portion Ta will be described. 
     First, in a state prior to forming a toner image on a first sheet S by the image forming section  5  of the image forming device  2 , each member is disposed as follows. That is, the first eject roller  39   a  is disposed at the position P 1 , the paddles  37  are disposed at the position Pa, the first tamper  38   a  is disposed at the position Pay, and the second tamper  38   b  is disposed at the position Pbx. The end guide  35   b  is disposed at the position Pey that is further away from the bottom portion  35   a.    
     Then, the toner image is formed on the first sheet S by the image forming section  5  of the image forming device  2 . As shown in  FIG. 1 , after the first sheet S on which the toner image is formed is reversed by the sheet reversing device  7  as required, the sheets S are supplied one at a time to the sheet processing device  3  through the discharge rollers  9 . 
     In the transporting device  10  of the sheet processing device  3  to which the first sheet S is supplied, the first sheet S is received through the entrance rollers  11 , and, if necessary, holes are punched in the first sheet S with the puncher  12 . Thereafter, the first sheet S is transported downstream towards the postprocessing device  30  through the first transporting rollers  13  and the second transporting rollers  14 . 
     The postprocessing device  30  receives the first sheet S through the receiving rollers  31 . The first sheet S that passes through the receiving rollers  31  is transported along the first traveling direction S 1  by the exit rollers  34 . The first sheet S passes between the compiling stacking section  35  and the first eject roller  39   a  and between the compiling stacking section  35  and the paddles  37 . 
     After the front edge in the first traveling direction S 1  of the first sheet S passes between the compiling stacking section  35  and the paddles  37 , the paddles  37  move downward from the position Pa in the direction of arrow U 1  in  FIG. 2 , and are disposed at the position Pb. This causes the paddles  37  to contact the first sheet S. Rotation in the direction of arrow R of the paddles  37  shown in  FIG. 2  causes the first sheet S to be pushed in the second traveling direction S 2  in  FIG. 2 , so that an edge portion of the first sheet S at the side of the end guide  35   b  contacts the end guide  35   b . Thereafter, the paddles  37  move upward in the direction of arrow U 2  in  FIG. 2 , separate from the first sheet S 1 , and are disposed again at the position Pa. 
     Then, after the compiling stacking section  35  receives the first sheet S, and the edge portion of the first sheet S at the side of the end guide  35   b  reaches the end guide  35   b , the first tamper  38   a  moves towards the compiling stacking section  35  in the direction of arrow C 2  in  FIG. 3  from the position Pay. At this time, the second tamper  38   b  is kept at the position Pbx. By this, the first tamper  38   a  pushes the first sheet S, and the first sheet S contacts the second tamper  38   b . Thereafter, the first tamper  38   a  moves away from the compiling stacking section  35  in the direction of arrow C 1  in  FIG. 3 , so that the first tamper  38   a  separates from the first sheet S, and is disposed again at the position Pay. 
     As in the above-described operation, a second sheet S and sheets S following the second sheet S having toner images formed thereon by the image forming section  5  have their edge portions aligned by the paddles  37  and the tampers  38  when they are successively supplied to the postprocessing device  30 . That is, with the first sheet S being aligned, the second sheet S is supplied, so that the second sheet S is aligned with the first sheet S. This also similarly applies to the case in which a third sheet S and sheets S following the third sheet S are supplied. Accordingly a preset number of sheets S is held by the compiling stacking section  35 , and the edge portions of the respective sheets S are aligned, to form a bundle of sheets S. 
     Then, the first eject roller  39   a  is moved downward from the position P 1  in the direction of arrow Q 1  in  FIG. 2 , and is disposed at the position P 2 . This causes the bundle of aligned sheets S to be nipped between the first eject roller  39   a  and the second eject roller  39   b , and to be fixed. 
     Next, the edge portions of the bundle of sheets S stacked on the compiling stacking section  35  are bound by the stapler  45 . More specifically, the binding device  40  is moved along the rail  44  by a motor (not shown) (refer to arrow A), so that the stapler  45  opposes a portion where a binding operation is to be performed. Then, a stapler motor (not shown) is driven, and the stapler  45  pushes a staple  41  into the bundle of sheets S, to perform the binding operation. At this time, the distance from an end of the staple  41  situated away from the first edge portion Sa to the first edge portion Sa becomes the distance d 2 . 
     The bundle of sheets S bound by the stapler  45  is discharged from the compiling stacking section  35  by the rotation of the first eject roller  39   a  in the direction of arrow T 1  in  FIG. 2 . Then, the bundle of sheets S passes through the opening  69 , and is discharged to the stacking section  70 . 
     Binding Operation at Corner Te 
     Next, an operation when the stapler  45  performs a binding operation at the corner Te of the bottom portion  35   a  will be described. Here, operational features that differ from those of the above-described image forming system  1  will only be described. 
     First, after the bundle of aligned sheets S is nipped by the first eject roller  39   a  and the second eject roller  39   b , and is fixed, when a motor (not shown) is driven, the binding device  40  moves along the rail  44 , and moves towards the corner Te of the bottom portion  35   a.    
     At the position where the binding device  40  is disposed adjacent to the corner Te, a motor (not shown) rotates, to rotate the stapler  45  (refer to arrow B). More specifically, the stapler  45  moves from a position where it is continuous with the stapleless binding mechanism  50  (refer to the stapler  45  illustrated by broken lines in  FIG. 5 ) to a position where it opposes the corner Te of the bottom portion  35   a  (refer to the stapler  45  illustrated by a solid line in  FIG. 5 ). In other words, first, the stapler  45  and the stapleless binding mechanism  50  are integrated to each other by being connected to each other through the joint  48 . Then, when the stapler  45  is rotated around the rotational shaft  47 , the stapler  45  moves in the direction in which it separates from the stapleless binding mechanism  50  while the connection between the stapler  45  and the stapleless binding mechanism  50  through the joint  48  is maintained. 
     The stapler  45  whose angle is changed is driven by the stapler motor (not shown) at the position opposing the corner Te. This causes the staple  41  to be pushed into the sheets S. 
     The stapler  45  is capable of being rotated (refer to arrow B) without moving the position of the stapleless binding mechanism  50  (for example, without rotating the stapleless binding mechanism  50 ). Here, for example, a portion of the binding device  40  that protrudes in an outer peripheral direction of the compiling stacking section  35  is smaller when only the stapler  45  is rotated than when both the stapler  45  and the stapleless binding mechanism  50  are rotated in order to cause the stapler  45  to oppose the corner Te. Therefore, in the exemplary embodiment, only the stapler  45  is rotated. Consequently, it is possible to reduce the size of the sheet processing device  3 . 
     Here, although the rotation of the stapler  45  by driving a motor is described as a method of changing the angle of the stapler  45 , the present invention is not limited thereto. 
     For example, it is possible to provide the stapler  45  with a hook, and to provide a side of the rail  44  that is close to the corner Te with a protrusion that is caught by the hook. As the binding device  40  moves towards the corner Te, the hook and the protrusion engage each other. When a force generated by the engagement of the hook and the protrusion is applied to the stapler  45 , the stapler  45  rotates around the rotational shaft  47 . 
     Further, a portion of the rail  44  on which the binding device  40  is placed may be curved. That is, a portion of the straight rail  44  that is close to the corner Te is curved so as to extend towards the corner Te. As the binding device  40  moves towards the corner Te, the stapler  45  receives a force that pushes it towards the corner Te from the curved portion of the rail  44 . When this force is received, the stapler  45  rotates around the rotational shaft  47 . 
     Binding Operation of Stapleless Binding Mechanism  50   
     Next, the case in which the stapleless binding mechanism  50  performs a binding operation at the front-side edge portion Ta will be described. 
     Here, as mentioned above, the area of the stapleless binding portion  51  is larger than the area of the staple  41 . Therefore, when, for example, transport positions of the sheets S in the image forming system  1  differ, the possibility with which the stapleless binding portion  51  having a large area overlaps images is increased. Therefore, when the stapleless binding mechanism  50  performs a binding operation, it is necessary to provide a sufficient distance from the images to the binding portion so as to reliably prevent the overlapping of the stapleless binding portion  51  and the images. 
     In order to provide the sufficient distance so as to reliably prevent the overlapping of the stapleless binding portion  51  and the images, in one mode, edges of the images formed on the sheets S are moved. In other words, the binding margin is widened. Further, in another mode, the position of the binding portion of the sheets S is moved away from the images. 
     By using either one of these two modes, it is possible to provide the sufficient distance from the images to the binding portion so as to reliably prevent the overlapping of the stapleless binding portion  51  and the images. Alternatively, a mode in which both of these modes are combined may also be used. These modes will hereunder be described. 
     Moving the Image 
     First, with reference to  FIG. 1  and  FIGS. 8A and 8B , the mode in which an edge of an image formed on a sheet S is moved will be described. Here, the operation that differs from the operation of the image forming system  1  when the above-described stapler  45  performs a binding operation at the front-side edge portion Ta will only be described. 
       FIGS. 8A and 8B  each illustrate the relationship between the position of the first edge portion Sa of a sheet S and the position of an image formed on the sheet S. FIG.  8 A shows the relationship between the position of the image and the sheet S when the stapler  45  performs a binding operation.  FIG. 8B  shows the relationship between the position of the image and the sheet S when the stapleless binding mechanism  50  performs a binding operation. 
     When the stapleless binding mechanism  50  performs the binding operation, before the image forming section  5  forms the image on the sheet S, first, the controller  80  sends a control signal to the image forming section  5  so that the position of the image that the image forming section  5  forms is changed. Then, the image forming section  5  that receives the signal sets the distance from the edge portion of the sheet to the image that it forms so that this distance differs from that when the stapler  45  performs the binding operation. 
     More specifically, the relationships are as shown in  FIGS. 8A and 8B . That is, the image forming section  5  is controlled so that the distance from the image edge Ia of the image (which is the edge of the image at the side of the first edge portion Sa) to the first edge portion Sa when the stapler  45  performs the binding operation differs from that when the stapleless binding mechanism  50  performs the binding operation. 
     When the stapler  45  performs the binding operation, the distance from the image edge Ia to the first edge portion Sa becomes a distance ds. In contrast, when the stapleless binding mechanism  50  performs the binding operation, the distance from the image edge Ia to the first edge portion Sa becomes a distance dt. The distance dt is longer than the distance ds by, for example, approximately 3 to 5 mm. 
     By changing the position of the image in this way, when the stapleless binding mechanism  50  performs the binding operation, a wider binding margin is provided. This makes it possible to reliably prevent the overlapping of the image and the stapleless binding portion  51 . 
     Here, in the exemplary embodiment, the position of the image is only changed without changing, for example, the size of the image that is formed on the sheet S by the image forming section  5 . The mode is one in which the image formed on the sheet S is moved along the sheet S. 
     However, the present invention is not limited thereto. Any structure that provides a wider binding margin when the stapleless binding mechanism  50  performs the binding operation may be used. 
     For example, the scale of the image that is formed when the stapler  45  performs the binding operation may be made to differ from that when the stapleless binding mechanism  50  performs the binding operation. More specifically, with the image when the stapler  45  performs the binding operation being a standard, the entire image when the stapleless binding mechanism  50  performs the binding operation may be scaled down without moving the center of the image. 
     Further, a structure that processes an image may also be used. More specifically, with the image when the stapler  45  performs the binding operation being a standard, the aspect ratio of the image when the stapleless binding mechanism  50  performs the binding operation may be changed. That is, the image is reduced in size in only a direction in which the image intersects the first edge portion Sa of the sheet S without moving the center in this direction. 
     Alternatively, each of the above-described modes may be combined. That is, the image may be scaled down while moving the image that is formed on the sheet S. Alternatively, the aspect ratio of the image may be changed while moving the image that is formed on the sheet S. 
     Moving the Binding Portion 
     Next, with reference to  FIG. 1  and  FIGS. 4A to 4C  and  FIGS. 9A and 9B , a mode in which the position of the binding portion of the sheet S is moved will be described. 
       FIGS. 9A and 9B  each illustrate the relationship between the position of the binding portion and the position of the image formed on the sheet S.  FIG. 9A  shows the relationship between the position of the staple  41  and the image.  FIG. 9B  shows the relationship between the position of the stapleless binding portion  51  and the image. 
     First, a comparative case in which the binding operation is performed by the stapler  45  will be described. Before the image forming section  5  forms the image on the sheet S, the controller  80  sends a control signal to the solenoids  35   d  so that the end guide  35   b  is disposed at a specified position. 
     When the stapler  45  performs the binding operation, if the solenoids  35   b  do not operate, the end guide  35   b  is disposed at the position Pey. Then, when the sheet S is disposed at the bottom portion  35   a  of the compiling stacking section  35 , and is subjected to the binding operation, the distance from the first edge portion Sa to the edge of the binding portion (staple  41 ) at the image side becomes a distance d 2 . The distance from the edge of the binding portion at the image side to the image edge Ia becomes a distance du. 
     In contrast, when the stapleless binding mechanism  50  performs the binding operation, if the solenoids  35   d  are operated, the end guide  35   b  is disposed at the position Pex. Then, when the sheet S is disposed at the bottom portion  35   a  of the compiling stacking section  35 , and is subjected to the binding operation, the distance from the first edge portion Sa to the edge of the binding portion (the stapleless binding portion  51 ) at the image side becomes the distance d 1 . The distance from the edge of the binding portion at the image side to the image edge Ia becomes a distance dv. 
     Here, the distance dv is either equal to or greater than the distance du. For example, the distance dv is greater than the distance du by approximately 3 to 5 mm. 
     By changing the position of the end guide  35   b  in this way, the distance dv becomes consequentially longer than the distance du. This makes it possible to reliably prevent the overlapping of the image with the binding portion. 
     As mentioned above, the distance d 1  is less than the distance d 2 . In relation to this, if the position of the stapleless binding portion  51  is moved towards the first edge portion Sa of the sheet S, the sheet S tends to be torn. That is, if a distance dw from the side of the stapleless binding portion  51  adjacent to the first edge portion Sa to the first edge portion Sa of the sheet S is short, the sheet S tends to be torn. Therefore, in order not to tear the sheet S, it is necessary for the distance dw to be longer than a certain width. 
     Other Modes 
     With reference to  FIG. 10 , another mode of moving the end guide  35   b  will be described.  FIG. 10  is a side view of the vicinity of the end guide  35   b  according to another mode. 
     As shown in  FIG. 10 , an operating plate  35   e  is disposed at the lower side of the end guide  35   b . The operating plate  35   e  is provided in an orientation intersecting the bottom portion  35   a . In addition, an end guide spring  35   c  is connected to one of the sides of the operating plate  35   e  at a position where the end guide spring  35   c  does not interfere with the operation of the binding device  40 . For example, a housing of the postprocessing device  30  (not shown) is secured to an end portion differing from an end portion of the end guide spring  35   c  that is connected to the operating plate  35   e . Further, a solenoid  35   d  is provided at a side of the operating plate  35   e  that is opposite to the side where the end guide spring  35   c  is disposed. The solenoid  35   d  is secured to, for example, the housing of the postprocessing device  30  (not shown). By operating the solenoid  35   d , the end guide  35   b  is moved towards the bottom portion  35   a , so that the end guide  35   b  is disposed at the position Pex where it is disposed close to the bottom portion  35   a . When the solenoid  35   d  is not operated, the end guide  35   b  is disposed at the position Pey where it is disposed further away from the bottom portion  35   a.    
     Although, in the above-described exemplary embodiment, the position of the binding device  40  is not moved in a direction intersecting the first edge portion Sa of a sheet S (that is, in a direction along the second edge portion Sb), the present invention is not limited thereto. For example, the binding device  40  includes a stage that is movable in a direction intersecting the rail  44 . A solenoid  35   d  that moves the stage in the direction intersecting the rail  44  is connected. By driving the solenoid  35   d , the binding device  40  is movable in the direction intersecting the first edge portion Sa of the sheet S. By using this structure, the distance from the first edge portion Sa of the sheet S to a binding portion may be changed. 
     Further, although, in the above-described exemplary embodiment, the stapleless binding mechanism  50  binds the sheets S using the flap  522  and the slit  521 , the present invention is not limited thereto. 
     Here, a stapleless binding mechanism  50  in another exemplary embodiment will be described with reference to  FIGS. 11A and 11B .  FIGS. 11A and 11B  illustrate a bundle of sheets S on which a stapleless binding operation is performed in another exemplary embodiment.  FIG. 11A  shows an example in which the binding operation is performed by forming arrow-like cut portions  511 .  FIG. 11B  shows an example in which the binding operation is performed by forming embossed marks  512 . 
     First, in a binding mode shown in  FIG. 11A , the arrow-like cut portions  511  are formed in portions of the bundle of sheets S. The arrow-like cut portions  511  are punched with the ends of their shafts being kept continuous with the sheets S. Then, the arrow-like cut portions  511  are raised upward, and engage with punched holes, to hold the bundle of sheets S. 
     In contrast, in a binding mode shown in  FIG. 11B , the bundle of sheets S is bound by forming the embossed marks  512  on portions of the bundle of sheets S. That is, a member (which forms the embossed marks  512  from an illustrated upper surface of the bundle of sheets S shown in  FIG. 11B  to the opposite surface of the bundle of sheets S) is pressed against the bundle of sheets S. This causes recessed portions to be formed at the surface of the bundle of sheets S that is capable of being seen in  FIG. 11B  (that is, protrusions are formed at the opposite surface of the bundle of sheets S), so that the binding operation is performed. 
     Further, although, in the above-described exemplary embodiments, as shown in  FIG. 5 , the stapler  45  and the stapleless binding mechanism  50  of the binding device each have a head, and the head of the stapler  45  rotates (refer to arrow B in  FIG. 5 ), the present invention is not limited thereto. For example, it is possible for the stapler  45  and the stapleless binding mechanism  50  to have a common head, and for only a member of the stapler  45  that pushes in the staples  41  to be rotated. 
     Further, although, in the above-described exemplary embodiments, the binding device  40  includes one stapler  45  and one binding mechanism  50 , the present invention is not limited thereto. For example, the binding device  40  may include two staplers  45  and a stapleless binding mechanism  50  disposed between the two staplers  45 . This structure makes it possible to obliquely dispose a staple  41  even at another corner of each sheet S which is situated at the side of the first edge portion Sa and which differs from the corner Se. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.