Abstract:
The present invention relates to a sheet processing apparatus having a stapling means disposed detachably for stapling to conveyed sheets, the stapling means being movably supported between an operation position for stapling conveyed sheets and a replacement position for detaching the stapling means from the apparatus, the stapling means comprising; a connection portion connected to the apparatus for receiving a control signal from the apparatus; a cable for transmitting the control signal from the connection portion to the stapling means; and an urging means for urging the cable toward the inner side of the stapling means.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a sheet processing apparatus and an image forming apparatus having the sheet processing apparatus and, more particularly, to a sheet processing apparatus avoiding occurrence of clamping wires for a staple holder and an image forming apparatus having the sheet processing apparatus. 
     2. Description of Related Art 
     Image forming apparatuses such as printers may conventionally have a sheet processing apparatus in which plural sheets on which images are formed or printed are subject to a processing such as stapling upon aligning each end properly to perform such a processing on the sheets to be delivered. As such a sheet processing apparatus, a known type disposed on a side surface on a sheet delivery outlet of an image forming apparatus, has a structure that sheets printed in the image forming apparatus are fed sheet by sheet from the delivery outlet and aligned at the each end to deliver the sheets upon processing. 
     A stapling mechanism section is generally disposed inside the housing of the sheet postprocessing apparatus. A widely known type has a structure that a housing lid is opened to handle paper jamming at the stapling mechanism section in the apparatus interior, to replace staples, and to replace the staple mechanism section, at times of occurrences of paper jamming at the stapling section, replacements of stapling, and malfunctions of the stapling mechanism section. 
     With these sheet processing apparatuses having such a stapling function, however, users have to laboriously open the housing lid to handle paper jamming or staple replacement through the stapling mechanism section located at the interior of the apparatus when paper jamming occurs or staple replacement is required at the staple section because the staple mechanism section is disposed at the inner side of the housing of the sheet processing apparatus. The users therefore have to go through a large number of actions during handling of paper jamming or staple replacement, and are subject to bad maneuverability as processing on the internal apparatus located inside the housing. These apparatuses also have disadvantages such that the apparatuses become structurally complicated as the apparatus housing is formed with the lid and thereby increase the costs. 
     A structure has been recently devised in which users can handle unit replacement properly during paper jamming processing, staple replacement or malfunction of the stapling section upon moving the unit directly in the accessing direction, where a housing of a unit of the staple mechanism section also serves as the outer housing of the sheet processing apparatus, and where the unit is movable and detachable from the sheet processing apparatus. 
     With such a structure, however, the staple unit or stapler requires a detachable connector cable where the power source of the stapler is supplied from the side of the sheet processing apparatus. The connector cable is prepared to have a longer length than the necessary length in consideration of handling easiness, but the cable may be clamped between the housing of the staple holder and the apparatus body when the staple holder is moved, attached or detached, or namely, so-called “wire clamping” may occur. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to prevent lime clamping of the cable for a staple holder. To accomplish the above object, a representative structure of the invention is of a sheet processing apparatus having a stapling means disposed detachably for stapling to conveyed sheets. The stapling means takes an operation position for stapling processing to a conveyed sheet and a replacement position for detaching the stapling means from the apparatus. The stapling means includes a connection portion connected to the apparatus for receiving a control signal from the apparatus, a cable for transmitting the control signal from the connection portion to the stapling means, and an urging means for urging the cable toward the inner side of the stapling means. 
     With this invention, thus, the stapling means has the urging means for urging the cable toward the inner side of the stapling means, and therefore, the cable of the stapling means is pulled inside the stapling means, so that wire clamping in which the cable is clamped between the stapling means and the apparatus is avoided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic cross section showing the whole structure of a sheet processing apparatus and an image forming apparatus; 
     FIG. 2 collectively includes FIGS.  2 ( a ) and  2 ( b ), which are cross sections showing a delivery roller and the sheet processing apparatus; 
     FIG. 3 collectively includes FIGS.  3 ( a ) and  3 ( b ), which are cross sections showing a sheet process apparatus; 
     FIG. 4 collectively includes FIGS.  4 ( a ) and  4 ( b ), which are illustrations showing operation of a sliding guide; 
     FIG. 5 collectively includes FIGS.  5 ( a ) and  5 ( b ), which are illustrations showing operation of the sliding guide; 
     FIG. 6 collectively includes FIGS.  6 ( a ),  6 ( b ), and  6 ( c ), which are illustrations showing a state in which sheets are aligned and stacked with the sliding guide; 
     FIG. 7 is a perspective view showing a printer to which the sheet processing apparatus is mounted; 
     FIG. 8 is an illustration showing a structure of a staple holder; 
     FIG. 9 is a right side view showing the sheet processing apparatus; 
     FIG. 10 collectively includes FIGS.  10 ( a ) and  10 ( b ), which are top views showing the sheet processing apparatus with movement of the stapler; 
     FIG. 11 collectively includes FIGS.  11 ( a ) and  11 ( b ), which are perspective views showing the sheet processing apparatus with movement of the stapler; 
     FIG. 12 collectively includes FIGS.  12 ( a ),  12 ( b ), and  12 ( c ), which are illustrations of operation when a staple holder is removed; 
     FIG. 13 is a perspective view showing the sheet postprocessing apparatus with movement of a paper jam treating housing; 
     FIG. 14 collectively includes FIGS.  14 ( a )  14 ( b ), and  14 ( c ) which are illustrations showing a movement of operation control switch and the vicinity; 
     FIG. 15 collectively includes FIGS.  15 ( a ) and  15 ( b ), which are perspective views showing the sheet postprocessing apparatus when the staple holder is removed; 
     FIG. 16 is a perspective view showing a staple holder in the first embodiment; 
     FIG. 17 is a perspective view showing the staple holder while removed in the first embodiment; 
     FIG. 18 is a perspective view showing the staple holder while removed in the second embodiment; 
     FIG. 19 is a perspective view showing the staple holder at the operation position in the second embodiment; 
     FIG. 20 is a perspective view showing the staple holder while removed in the third embodiment; and 
     FIG. 21 is a perspective view showing the staple holder at the operation position in the third embodiment. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings, the embodiments of the invention are described in detail. In the following embodiments, exemplified is a sheet processing apparatus mounted to a printer apparatus as represented by a laser beam printer. 
     First Embodiment 
     First, referring to FIG. 1 to FIG. 6, structures of a printer body and a sheet processing apparatus, a series of operations in the first embodiment are described. FIG. 1 is a schematic cross section showing the whole structure of a sheet processing apparatus and an image forming apparatus. 
     In FIG. 1, numeral  100  indicates a printer body, which is solely coupled to a computer or coupled to a network such as a LAN or the like, and which forms images on sheets with a prescribed image forming process based on image information transmitted from the computer or the network and a print signal and delivers the printed sheets. 
     In a meantime, the sheet processing apparatus  300  is an apparatus that stacks, on a first sheet stacking portion, sheets delivered from the printer  100  to the exterior thereof via a conveyance portion in the sheet processing apparatus as facing down state in which the image side is placed downward, aligns the sheets with the aligning means, and delivers on the stacking portion  325  of the sheet processing apparatus the stacked sheets upon stapling the sheets at a single or plural portions of the sheets where the sheets are bundled at each prescribed job, or delivers sheets as facing down on the stacking portion  325  of the sheet processing apparatus. 
     The sheet processing apparatus  300  and the printer body  100  are electrically coupled with a cable connector not shown. The sheet processing apparatus  300  has a housing  300 A for containing each part and is detachably attached to an apparatus body  100 A of the printer body  100  as described below. 
     Each structure of portions of the printer body  100  is described along the conveyance path at of the sheet S to be conveyed. In the printer  100 , plural sheets S are stacked in a feeding cassette  200 , and various rollers separately conveys the topmost sheet one by one among the plural sheets. According to a prescribed printer signal fed from the computer or the network, toner images are transferred to the sheets S fed from the feeding cassette  200  on a top side of the sheets at an image forming section  101  for forming toner images by an image forming process of a so-called laser beam type in the printer body  100 , and subsequently, are permanently fixed upon application of heat and pressure at a fixing unit  120  located on a downstream side. 
     The sheet S to which images are fixed is turned to reverse the image side by being returned through a sheet conveyance path curving in a substantially letter U shape reaching to delivery rollers  130  as shown in FIG. 1, and is delivered as facing down to the exterior from the printer body  100  by the delivery roller  130  in a state that the image side faces down. The sheet S is selected to be delivered either to a face-down (FD) delivery portion  125  mounted on a top of the printer body  100  or to the stacking portion  325  of the sheet processing apparatus  300  according to the determination of the position of a flapper  150  in the printer  100  based on the control signal from the controller, not shown. 
     Then, the structure of the sheet processing apparatus, and motions of the respective portions when the sheet conveyed from the delivery roller  130  moves toward the sheet processing apparatus  300 , are described in reference with FIG.  2  and FIG.  3 . Herein, FIGS.  2 ( a ) and  2 ( b ) are cross sections of the delivery roller and the sheet processing apparatus; FIGS.  3 ( a ) and  3 ( b ) are cross sections of the sheet processing apparatus. 
     In FIG. 2, numeral  330   a  indicates a delivery upper roller, and numeral  330   b  indicates a delivery lower roller. Numeral M is a jogger motor as a drive source; numeral  322  indicates a paddle; numeral  323  is a reference wall for hitting the sheet rear end. As shown in FIG. 2, the delivery roller paid  303  structured of the delivery upper roller  330   a  and the delivery lower roller  330   b  is disposed upwardly on a downstream side of the flapper  150  described above in the sheet conveyance direction and driven to rotate by a drive motor, not shown. 
     The delivery upper roller  330   a  is supported at the axis thereof to an arm  331  pivotally movable around a paddle shaft  350  as a center. The jogger motor M is for driving respective sliding guides  301 ,  302  described below, and in this embodiment, a stepping motor is used. 
     The paddle  322  is made of an elastic material such as a rubber or the like, and plural paddles  322  are secured to the paddle shaft  350  in a direction perpendicular to the sheet conveyance direction. The sheets S are moved to a direction in opposition to the sheet conveyance direction by driving and rotating the paddle shaft  350  in a clockwise direction, and the end face of the sheets S comes in contact with the reference wall  323  to align the sheets S. 
     As shown in FIG. 3, with the sheet processing apparatus  300  in this embodiment, the sliding guide  301  and the sliding guide  302  are formed as described below in detail as a guide member for aligning the sheets in the sheet width direction. 
     In the sheet processing apparatus  300 , when stapling is performed based on a command already outputted from the computer or the like, the flapper  150  moves pivotally in the counterclockwise direction in FIG.  2 ( a ) by a link, not shown, from a solenoid, not shown, before the sheet S to be stapled is delivered by the delivery roller  130 , and the sheet path is switched to the sheet processing apparatus  300  where the flapper  150  stops as it comes in contact with the stopper at the position shown in FIG.  2 ( a ). The sheet S is thus loaded to an inlet sensor  390  of the sheet processing apparatus  300  by a roller pair formed at the printer body  100 . 
     The sheet S loaded in the sheet processing apparatus  300  rotates a flag of the inlet sensor  390  in the clockwise direction, and the flag renders the beam transmit to the photosensor to make the detection. Then, the inlet roller pair  363  conveys the sheet upward. 
     This sheet processing apparatus  300  can deliver the sheets in a stacking manner on the stacking portion  325  of the sheet processing apparatus upon stapling the sheets and can deliver the sheets in a stacking manner on the stacking portion  325  of the sheet processing apparatus as simply facing down, as well. First, as shown in FIG. 2, the operation for delivering sheets in a stacking manner on the stacking portion  325  of the sheet processing apparatus, is described. 
     At that time, as shown in FIG. 5, the bottom surfaces of the right side sliding guide  301  and the left side sliding guide  302  with respect to the sheet loading direction, escape to a position not in contact with the sheets S to be loaded, or namely, to a position outward in the width direction by a prescribed amount from the sheet S, and therefore, the sheets S are directly conveyed to the stacking portion of the sheet processing apparatus. 
     The sheet conveyed from the inlet roller pair  363  is conveyed by the delivery roller pair  330  upon passing the opening of the staple H after passing through a staple roller pair  320  and stacked on a staking portion  325  of the sheet processing apparatus. 
     Next, referring to FIG. 6, operation to deliver the sheets in a staking manner on the stacking portion  325  of the sheet processing apparatus upon stapling is described. 
     At that time in the sheet processing apparatus  300 , as shown in FIG.  3 ( a ), a reference pin  303  and a reference pin  304  formed at the wall surfaces of the right side sliding guide  301  and the left side sliding guide  302  with respect to the sheet loading direction, escape to a position not in contact with the sheet loading direction, escape to a position not in contact with the sheets S to be loaded so as not to interfere with the sheets S to be loaded. The interval between the end of the bottom surfaces of the sliding guides is narrower than the width of the sheet, and the sliding guides wait the entry of the sheets S. This position is referred to as a waiting position. 
     The sheet conveyed from the inlet roller pair  363  is conveyed by the delivery roller pair  330  upon passing the opening of the staple H after passing through a staple roller pair  320  onto a guide surface of an intermediate stacking portion  300 B made of the sliding guide  301  and the sliding guide  302 . 
     The guide surface of the intermediate stacking portion  300 B is slanted by a prescribed angle with respect to the horizontal direction as shown in FIG.  6 ( a ), and has slanted angles different to each other between the upstream side and the downstream side in the sheet loading direction. More specifically, a bending section  300 C bending with a slanted angle α (see FIG. 1) is formed between a prescribed section on an upstream side and a prescribed section on a downstream side. The guide surface of the intermediate stacking portion  300 B prevents the sheets S not guided by the respective sliding guides  301 ,  302  from bending at the center, by having such a bending portion  300 C. 
     Immediately after the first sheet is conveyed onto a surface made of the sliding guide  301  and the sliding guide  302 , the arm  331  rotates in the counterclockwise direction to escape upward the delivery upper roller  330   a  rotatably supported to the arm  331 , thereby isolating the delivery roller pair  330 , and at the same time, cutting the drive coupled to the delivery roller pair  330  to stop the rotation of the delivery upper roller  330   a  and the delivery lower roller  330   b . When the rear end of the sheet S passes by the staple roller pair  320  totally, the sheet returns by the self-weight in a direction opposition to the conveyance direction and moves closer to a direction of the reference wall  323 . 
     Subsequently, upon operation solely of the left side sliding guide  302 , aligning operation in the width direction begins for respective sheets stacked on the intermediate stacking portion  300 B. More specifically, the sliding guide  302  is driven by the motor M to move on the right side in FIG. 3, thereby rendering the reference pin  304  formed at the sliding guide  302  contact with the left side surface of the sheet S to push the sheet S toward the sliding guide  301 . 
     The right side surface of the sheet S then hits the reference pin  303  formed at the sliding guide  301 , and thereby alignment in the width direction of the sheets is made. It is designed that the sheets S move to a stapling position defined at a position where the sheets S contacts the reference pin  303  and are aligned. After the alignment operation, the sliding guide  302  moves to a direction expanding the width of the sheet S, and the apparatus become responsible to the subsequent conveyance of the sheet at the waiting position. 
     The structure of the sliding guide is now described in detail. FIGS.  3 ( a ) and  3 ( b ) are cross sections of the sheet processing apparatus; FIGS.  4 ( a ) and  4 ( b ) and FIGS.  5 ( a ) and  5 ( b ) are illustrations for describing operation of the sliding guide. 
     The respective sliding guides  301 ,  302  are reciprocally movable in a right and left direction in FIGS.  3 ( a ) and  3 ( b ), or a direction perpendicular to the sheet conveyance direction by being guided with the guide pins  313   a  formed at the molded frame and the guide pins  313   b  formed at the metal plate frame, four in total, and move according to transmission of the drive force of the jogger motor M. 
     The sliding guides  301 ,  302  are in a cross-sectionally rectangular U-shape as shown in FIG.  3 ( b ) when seen from the downstream side of the sheet conveyance direction, by respective walls for guiding each edge of the sheet S and a supporting portion for supporting the up and down sides of the sheet S. The sliding guides  301 ,  302  has a structure to support the respective sheets delivered onto the intermediate stacking portion  300 B by the lower surface of the rectangular U-shape and not to guide the center in the width direction of the sheet. 
     A sliding rack portion  310  having a planer gear meshing a stepwise gear  317  is formed at the sliding guide  302 . In a meantime, a sliding rack portion  312  having a planer gear meshing a stepwise gear  317  is formed at the sliding guide  301 . The sliding rack portion  312  is formed so as to be movable correlatively to the sliding guide  301  via a coil spring  314 . The spring  314  has an end in contact with the sliding guide  301  and the other end in contact with the sliding guide  312  and is urging the sliding guide  301  and the sliding rack  312  in an expanding direction. The sliding rack  312  has a rectangular hole  312   a  for moving an embossing portion  310   a  on a side of the sliding guide  301 . 
     The two reference pins  303  made of a metal excellent in resisting wear are formed on a side wall of the sliding guide  301 , and the two reference pins  304  are formed on a side wall of the sliding guide  302 . When sheets are aligned, the sliding guide  302  moves as described below to contact the reference pin  304  and the reference pin  303  with respective edges of the sheet. The sliding guide  301  and the sliding guide  302  are supported in the height direction by the stepwise gear  317  and the jog metal plate frame. The stapler H is stationally disposed on a side of the sliding guide  301  to staple the respective sheets at the left upper corner of the image side of the image-formed sheets. 
     Referring to FIG. 3 to FIG. 5, operation of the sliding guides  301 ,  302  is described. When the sheet processing apparatus  300  is turned on, the stapling roller  320  driven by the drive motor begins rotating, and then, as the jogger motor M rotates to rotate the stepwise gear  317 , the sliding rack  310  of the sliding guide  302  is driven to escape outwardly. With the sliding guide  301 , when the jogger motor M rotates to rotate the stepwise gear  317 , the sliding rack  312  correlatively moves, and after the rectangular hole  312   a  of the sliding rack  312  contacts to the end on a right side in FIG. 3 of the embossing portion  310   a  of the sliding guide  301 , the sliding guide  301  is pushed by the rectangular hole  312   a  and escapes outwardly. 
     A slit portion  301 S is formed at the sliding guide  301 . When the slit portion  301 S moves to a prescribed escaping point, the photosensor  316  passes a beam, and the jogger motor M stops at that time. This position is defined as a home position. 
     The two reference pins  303  made of a metal excellent in resisting wearing are formed on a side wall of the sliding guide  301 , and the two reference pins  304  are formed on a side wall of the sliding guide  302 . When sheets are aligned, the sliding guide  302  moves as described below to contact the reference pin  304  and the reference pin  303  with respective edges of the sheet. The sliding guide  301  and the sliding guide  302  are supported in the height direction by the stepwise gear  317  and the jog metal plate frame. The stapler H is stationally disposed on a side of the sliding guide  301  to staple the respective sheets at the left upper corner of the image side of the image-formed sheets. 
     Referring to FIG. 3 to FIG. 5, operation of the sliding guides  301 ,  302  is described. When the sheet processing apparatus  300  is turned on, the stapling roller pair  320  driven by the drive motor begins rotating, and then, as the jogger motor M rotates to rotate the stepwise gear  317 , the sliding rack  310  of the sliding guide  302  is driven to escape outwardly. With the sliding guide  301 , when the jogger motor M rotates to rotate the stepwise gear  317 , the sliding rack  312  correlatively moves, and after the rectangular hole  312   a  of the sliding rack  312  contacts to the end on a right side in FIG. 3 of the embossing portion  301   a  of the sliding guide  301 , the sliding guide  301  is pushed by the rectangular hole  312   a  and escapes outwardly. 
     A slit portion  301 S is formed at the sliding guide  301 . When the slit portion  301 S moves to a prescribed escaping point, the photosensor  316  passes a beam, and the jogger motor M stops at that time. This position is defined as a home position. 
     When a signal for entering the sheet S to the sheet processing apparatus  300  is inputted from the printer body  100  to the sheet processing apparatus  300 , the jogger motor M rotates, and the sliding guide  301  and the sliding guide  302  move inside and stop at positions wider by a prescribed amount than the width of the entering sheet S. The sliding guide  301  at that position enters in a state not movable further inward whereas the stopper  301   b  contacts with the end face  313   c  of the guide pin  313   a.  This position shown in FIGS.  3 ( a ),  3 ( b ), is defined as a waiting position, and this waiting position becomes a reference position when the side surface of the sliding guide  301  is performing for alignment. 
     In this embodiment, when the side (or width) of the sheet S is the largest size that is able to make passage, the waiting position of the sliding guide  301  and the sliding guide  302  is set to have a space on each end in the width direction to become a prescribed amount d on each end. 
     It is to be noted that when the sheets having a width narrower than that are aligned at the sheet processing apparatus  300 , the sliding guide  301  moves on a right side by a portion corresponding to this, and thereby the space on the left side in FIG. 3 at the waiting position always becomes a prescribed amount d. Meanwhile, in this situation, the space between the sheet and the sliding guide  302  becomes wider than the prescribed amount d by a half of the narrowed width. 
     As shown in FIGS.  4 ( a ) and  4 ( b ), after alignment is made in the lateral direction by the sliding guides  301 ,  302 , both of the sliding guides escape a little outwardly, thereby rendering the regulation in the lateral aligning direction of the sheets in a rough state, and thereby rendering the sheets S movable in the sheet conveyance direction. Subsequently, as shown in FIG.  6 ( b ), the paddle  322  rotates one time in a clockwise direction around the paddle shaft  350  as a center and comes in contact with the top surface of the sheet S, thereby aligning the sheets S by hitting the sheets S to the reference wall  323 . 
     Those operations make possible alignments in the sheet conveyance direction and in the direction perpendicular to the sheet conveyance direction. To keep this aligned state, as shown in detail A of FIG.  4 ( a ), a stamping means  400  is provided near the right end of the aligned sheets for pushing the aligned sheets by moving a lever having a frictional member in the up and down direction as shown in cross section A, and the lever pushes the top side of the sheet after the alignment operation is finished but before the subsequently entered sheet hits the aligned sheets, thereby avoiding the subsequent sheet to move the aligned sheets. 
     In operation for the next and following sheets, when the next and further sheets are conveyed, the delivery roller pair  330  is isolated. Therefore, when the rear end of the sheet S totally passes through the staple roller pair  320 , the sheet returns by the self-weight in a direction opposite to the conveyance direction and moves toward the reference wall  323 . Because the following alignment operation is exactly the same as the operation for the first sheet, a description is omitted. 
     Such operations are repeated, and where the laser nth sheet (Sn) of the one job is aligned, the respective reference pins  304  formed at the sliding guide  302  push the left side surface of the sheet to the respective reference pins  303  of the sliding guide  302 , and stapling is made at a position of the rear end right side with a compact stapler H located on a rear end right side of the sheet bundle while the movement of the sliding guide  302  is stopped as shown in FIG.  4 . 
     According to this structure and operation, during the alignment operation of the respective sheets, the sliding guide  301  stops and does not move at the reference position, and the sliding guide  302  solely moves to align the left side end of the respective sheets at the reference position, so that the stapling processing is accurately, surely performed by the stapler H stationally disposed on a side of the sliding guide  301 . Moreover, even where the widths of the respective sheets loaded at one job are deviated, or where the sheet size is changed from, e.g., the LTR to the A4 in the one job, since the positions of the left ends of the sheets are aligned at a point, the stapling processing with the stapler H is finished accurately and beautifully, and an excellent advantage is obtained. 
     In the first embodiment, when the stapling is thus ended, as shown in FIG. 6, the arm  331  rotates in the clockwise direction to move the delivery upper roller  330   a  rotatively supported to the arm  331  downward, and drive is coupled to both rollers of the delivery roller pair  330  at the same time that the delivery roller pair  330  is formed, thereby rendering the delivery upper roller  330   a  and the delivery lower roller  330   b  begin to rotate. 
     With this operation, the bundle of the sheets S is nipped by the delivery upper roller  330   a  and the delivery lower roller  330   b , and conveyed onto a surface made of the sliding guide  301  and the sliding guide  302 . 
     When the bundle of the sheets S is completely delivered from the delivery roller pair  330 , the jogger motor M drives to rotate, and thereby, the sliding guide  302  moves in an isolating direction from the state shown in FIG.  4 . It is to be noted that when the sliding guide  302  begins rotating, in regarding the side of the sliding guide  301 , sliding rack  312  moves to the right side in FIG. 4, and the sliding guide  301  itself does not move immediately. 
     When the position of the sliding guide  302  passes through the waiting position shown in FIG. 3, the rectangular hole  312   a  of the sliding rack  312  comes in contact with the end surface of the embossing portion  301   a  of the sliding guide  301 , and the sliding guide  301  begins moving to the right side in FIG. 3, thereby moving both of the sliding guides  301 ,  302 . 
     The bundle of the sheets S already stapled is dropped down as shown in FIG.  6 ( c ) when the interval of the sliding guides  301 ,  302  for supporting the sheets becomes around the sheet width or wider. Thus, the sheet bundle drops to the stacking portion  325  of the sheet processing apparatus and is stacked. 
     The above description is the structure and a series of the operations of the printer body  100  and the sheet processing apparatus  330  in the first embodiment. 
     Next, referring to FIG. 7 to FIG. 14, a structure of a compact stapler H placed at a rear end right side of the sheet bundle in the first embodiment of the invention is described. 
     As shown in FIG. 8, the stapler H is structured of a stapler body  503 , a staple cartridge  504 , and a staple cover  505 , as a staple holder H (stapling means). FIG. 9 is a right side view of the sheet processing apparatus in this embodiment. As shown in FIG. 9, the staple cover in the first embodiment also serves as an outside of a housing of the sheet processing apparatus. 
     The staple holder in this embodiment is able to rotate around a shaft  506  as a center as shown in FIG.  10 ( a ), FIG.  11 ( a ). The staple holder is structured to hold staples with clicking feelings by a latch mechanism, not shown, at a staple operation position (see, FIG.  10 ( a ) and FIG.  11 ( a ), hereinafter referred to as staple operation position) and at a staple holder replacement position (see, FIG.  10 ( a ) and FIG.  11 ( a ), hereinafter referred to as staple holder replacement position). 
     Next, user&#39;s manipulation method when staples are stacked at the staple portion or when the staple portion becomes out of order, with the sheet processing apparatus of such a structure having a staple stacker function, is described. 
     As shown in FIG.  10  and FIG. 11, when staple stacking occurs at the staple portion or when the staple portion becomes out of order, the user directly moves the staple holder pivotally from the staple operation position to the staple replacement position around the shaft  506  as a center by hand. At that time the staple holder H is supported by a latch mechanism not shown at the staple operation position (a) with constant force, but the retaining force is released when the staple holder moves from the staple operation position (a) upon rotation by hand. 
     At the staple replacement position (b), as shown in FIG.  10 ( b ), a projecting portion  601  including a rotary center shaft  506  located at a top of the staple holder enters in an exposed state. As shown in FIG. 12, the user can bend the projecting portion  601  by pushing a side of the projecting portion  601  from the above state and can pull out the rotary center shaft  506  from the shaft hole  602  formed in the sheet processing apparatus  300 , thereby removing the staple holder H from the sheet processing apparatus. With this structure, the staple operation position (a) can improve the external appearance because the projecting portion  601  serving as the staple holding removing means is hidden. 
     The sheet processing apparatus  300  in this embodiment is formed as shown in FIG. 13 with a paper jam treating cover (paper jam treating means)  508  for handling paper jamming at the conveyance portion. With this structure, the user may be mistakenly clamped by the staple from a malfunction because the stapling section of the stapler H is not covered during a paper jam treating period. As shown in FIG. 11, also at the staple replacement position (b), the user may be mistakenly clamped by the staple from a malfunction where the stapling section of the stapler H is exposed to the exterior. 
     In this embodiment, as shown in FIG. 14, the apparatus is formed inside with an operation control switch  509  of the sheet processing apparatus, a link  512  for supporting a shaft  511  movable rotatably around a shaft  510 , a link lever  513  pivotally movable around the shaft  511 , a switch lever  514  formed at the staple cover  505 , and a switch lever  515  formed at the paper jam treating cover  508 . 
     As shown in FIG.  14 ( a ), where the staple holder H is at the staple operation position (a) and where the paper jam treating cover  508  is at a closed position, the operation control switch  509  is turned on by the link lever  513  to make the sheet processing apparatus enter into an operable state. 
     Furthermore, as shown in FIG.  14 ( b ), where the staple holder H is other than at the staple operation position (a), the operation control switch  509  is turned off because the link lever  513  pushed by the switch lever  514  of the stable cover  505  is moved pivotally, thereby making the sheet processing apparatus enter in a non-operable state. Therefore, the apparatus is designed so that, when the stapling section is exposed to the exterior at the staple replacement position (b), the user may not be clamped mistakenly with a staple by a malfunction. 
     As shown in FIG.  14 ( c ), where the paper jam treating cover  508  is at an open position, the operation control switch  509  is turned off because the link lever  513  moves away from the operation control switch  509  by the link  512  pushed by the switch lever  515  of the paper jam treating cover  508  is moved pivotally around the shaft  512  as a center to move the shaft  511 , thereby making the sheet processing apparatus enter in a non-operable state. Therefore, the apparatus is designed so that, when the stapling section of the stapler H is exposed upon opening of the paper jam treating cover  508 , the user may not be clamped mistakenly with a staple by a malfunction. 
     In this embodiment, the connector is necessarily taken out as shown in FIG.  15 ( b ), because a cable connector (connecting portion)  603  coming out of the staple holder H and a connector  604  on a side of the sheet processing apparatus are coupled to each other at a time that the staple holder H is removed from the sheet apparatus processing as shown in FIG.  15 ( a ). Similarly, when the staple holder is attached to the sheet processing apparatus, the staple holder is attached after the cable connector  603  is coupled, and the holder is returned to the staple operation position (a) upon moving pivotally from the staple replacement position (b). 
     With this structure, the cable  605  requires a longer length to some extent for coupling and uncoupling the connector while the holder is attached and detached. The cable  605  may be loosened to be bent during pivotal movement of the staple holder during the attachment of the staple holder, and the cable  605  may be clamped at a gap or the like between the staple holder and the sheet processing apparatus. 
     In this embodiment, as shown in FIG. 16, a wire spring  606  (urging means) is attached inside the staple holder upon securing a part of the cable  605 . With this structure, while the connector is attached or detached, work is done upon pulling out of the cable  605  in opposing the urging force of the wire spring  606  by pulling the connector  603  as shown in FIG.  17 . The shaft  506  of the staple holder is then fitted into the shaft hole  602  (see, FIG. 12) of the sheet processing apparatus  300  as described above and is moved pivotally to allow the staple holder H to be attached. Where the staple holder H is brought close to the sheet processing apparatus  300 , the cable  605  is pulled in the staple holder H by urging force of the wire spring  606 , so that the cable  605  exposed as bent during pivotal movement of the staple holder H may not be clamped between the staple holder H and the sheet processing apparatus  300 . 
     It is to be noted that the wire spring  606  can be of a structure contacting an end of the wire spring  606  with the metal portion of the sheet processing apparatus when the staple holder H is attached to the sheet processing apparatus  300  where the attaching position of the wire spring  606  is selected properly. With such a structure, the wire spring  606  may function as a ground for the stapler. 
     In the first embodiment, the apparatus thus constituted can make the staple holder H separate from the sheet processing apparatus with a simpler and less expensive structure than conventional apparatuses, so that controllability such as loading work and arrangement work of staples can be improved, and so that safety in work can be realized readily. Where the wire spring  606  is used as the urging means for the cable  605 , clamping the cable  605  is avoided at a gap between the staple holder H and the sheet processing apparatus  300 , which otherwise occurs due to a loosen cable  605  when the staple holder H is attached and moved pivotally, so that the connector is easily attached and detached. 
     The Second Embodiment 
     Next, a compact stapler H located on a rear end right side of the sheet bundle in the second embodiment of a sheet stacking apparatus according to this invention is described. Some description is omitted by assigning the same reference numbers to the same portions whose descriptions are repetitive of the first embodiment. 
     As described above, the connector  604  is necessarily disengaged because the cable connector  603  coming out of the side of the staple holder H and the connector  604  on a side of the sheet processing apparatus at a time when the staple holder H is removed from the sheet processing apparatus. Similarly, when the staple holder is attached to the sheet processing apparatus, the staple holder is attached after the cable connector  603  is coupled, and the staple holder is moved pivotally from the staple replacement position (b) and returned to the staple operation position (a). 
     With this structure, the cable  605  requires a longer length to some extent for coupling and uncoupling the connector  603  before or after work for attaching or detaching the staple holder. The cable  605  may be loosened to be bent during pivotal movement of the staple holder H 1  when the staple holder H is attached to the sheet processing apparatus after the attachment of the cable connector  603 , and the cable  605  may be clamped between the staple holder and the sheet processing apparatus. 
     As shown in FIG.  18  and FIG. 19, in this embodiment, a bobbin (winding shaft)  607  for winding the cable is provided inside the staple holder for the cable  605 . As shown in FIG. 18, while the connector is attached or detached, the cable  605  is unwound from the bobbin  607 , and the loosen cable  605  is pulled out to make the connector attached or detached. As shown in FIG. 19, where the staple holder H is attached to the sheet processing apparatus  300  and moved rotatively, the cable  605  is wound around the bobbin  607  as the staple holder H rotates, thereby preventing the cable from being loosen to be exposed to the exterior. It is to be noted that a winding amount at a time of rotation can be increased as the bobbin  607  is placed away from the rotation center of the rotational shaft  506  of the staple holder H. 
     With this structure, in the second embodiment, the apparatus can realize improvements of controllability at a time of replacement work of the staple holder H in accompany with loading work of the staples and malfunctions of the staple section and safety in work with a simpler and more inexpensive structure than conventional apparatuses. Occurrence of clamping the cable is avoided at a gap between the staple holder and the sheet processing apparatus, which otherwise occurs due to a loosen cable when the staple holder H is moved pivotally. 
     The Third Embodiment 
     Next, a compact stapler H located on a rear end right side of the sheet bundle in the third embodiment of a sheet stacking apparatus according to this invention is described. Some description is omitted by assigning the same reference numbers to the same portions whose descriptions are repetitive of the first embodiment. 
     As shown in FIG.  20  and FIG. 21, in this embodiment, the cable  605  itself is structured as wound in a coil shape, enabling to be extendable by pulling one end of the cable. As shown in FIG. 20, with such a structure, the cable  605  wound in a spiral shape can be unwound and pulled out by pulling the connector  603  while the connector  603  is attached or detached to the sheet processing apparatus  300 , thereby allowing the connector attaching and detaching work as the whole length of the cable  605  is extended. As shown in FIG. 21, when the staple holder H is attached to the sheet processing apparatus, the cable  605  is not clamped between the staple holder and the sheet processing apparatus during the rotation of the staple holder H, because the cable  605  is wound in a spiral shape to be short and does not become loosened as the staple holder H is placed close to the sheet processing apparatus  300 . 
     With such a structure, in the third embodiment, the apparatus can realize improvements of controllability at a time of replacement work of the staple holder H in accompany with loading work of the staples and malfunctions of the staple section and safety in work with a more inexpensive structure than conventional apparatuses. Occurrence of clamping the cable is avoided at a gap between the staple holder and the sheet processing apparatus, which otherwise occurs due to a loosen cable when the staple holder H is moved pivotally, so that the connector is attached and detached readily. 
     Other Embodiments 
     In the above embodiments, exemplified is a printer as an image forming apparatus, but the invention is not limited to this, and photocopiers and facsimile machines can be used.