Abstract:
A stapler apparatus may be provided. More specifically, a stapler apparatus capable of automatically stapling a bundle of sheets output from an image forming apparatus such as a copy machine, a printer, a facsimile or the like may be provided. The stapler includes: a guide plate in which a slot having a branch structure has been formed; a moving frame which is reciprocatively movable on the guide plate; a rotation frame which is rotatable on the moving frame and includes a plurality of levers mounted thereon, the plurality of levers moving along the inside and outside of the slot or change paths; a path change member which changes a movement path of any one of the plurality of levers; and a stapler which is mounted on the rotation frame and is in conjunction with the rotation frame.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Priority is claimed under 35 U.S.C. §119 to Korean Patent Application No. 10-2016-0015664, filed Feb. 11, 2015, the entirety of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    Field 
         [0003]    This embodiment relates to a stapler apparatus and more particularly to a stapler apparatus capable of automatically stapling a bundle of sheets output from an image forming apparatus such as a copy machine, a printer, a facsimile or the like. 
         [0004]    Description of the Related Art 
         [0005]    In general, the structure of an image forming apparatus such as a copy machine, etc., includes a sheet post-processing device which post-processes a sheet discharged from the side of the image forming apparatus. The sheet post-processing device stacks sheets copied and discharged from the image forming apparatus in an upper tray, causes the sheet on which operations such as copying, etc., have been completed to be punched by using a punch, or staples the sheet by a stapler and then stacks the sheets in a lower tray. The structure of a stapler apparatus constituting the sheet post-processing device has been variously developing. For example, the stapler apparatus staples the cross section of the transferred sheet while moving in the form of a straight line, or staples a side edge of the sheet at a 45 degree angle. 
         [0006]    Korean Patent Application Laid-Open Publication No. 10-2012-0015626 (hereafter, referred to as Patent Document 1) discloses a stapler apparatus enabling a stapler to softly move rotationally on both sides thereof. 
         [0007]    The stapler apparatus of the Patent Document 1 staples a bundle of sheets arranged within the sheet post-processing device  2 . 
         [0008]    According to the stapler apparatus of the Patent Document 1, it is possible only to obliquely staple a corner of a bundle of sheets arranged within the sheet post-processing device  2 . That is, the stapler apparatus of the Patent Document 1 cannot perform flat-stapling. In other words, the stapler apparatus of the Patent Document 1 cannot staple in parallel with one side of the sheet. 
       BRIEF SUMMARY 
       [0009]    One embodiment is a stapler apparatus including: a guide plate in which a slot having a branch structure has been formed; a moving frame which is reciprocatively movable on the guide plate; a rotation frame which is rotatable on the moving frame and includes a plurality of levers mounted thereon, the plurality of levers moving along the inside and outside of the slot or change paths; a path change member which changes a movement path of any one of the plurality of levers; and a stapler which is mounted on the rotation frame and is in conjunction with the rotation frame. 
         [0010]    The slot may include a reference slot and the plurality of branch slots which branch from one end of the reference slot. The plurality of levers may include a moving lever moving within the slot and include a path change lever moving outside the slot. The path change member may change a movement path of the path change lever and causes the moving lever to enter, from the reference slot, into any one of the plurality of branch slots which extends in a direction different from an extension direction of the reference slot. 
         [0011]    When the path change member does not change the movement path of the path change lever, the moving lever may enter, from the reference slot, into one of the plurality of branch slots which extends in a direction the same as an extension direction of the reference slot. 
         [0012]    The slot may include a reference slot, a first branch slot which branches from one end of the reference slot, and a second branch slot. The plurality of levers may include a moving lever which moves within the reference slot, the first branch slot, and a second branch slot. When the moving lever enters the first branch slot from the reference slot and moves by a predetermined distance and then moves in a reverse direction, the moving lever may enter the reference slot from the first branch slot. When the moving frame moves in a forward direction immediately after the moving lever enters the reference slot, the moving lever may enter the second branch slot from the reference slot. 
         [0013]    The slot may include ,a reference slot, a first branch slot which branches from one end of the reference slot, and a second branch slot. The plurality of levers may include a moving lever which moves within the reference slot, the first branch slot, and a second branch slot, and may include a path change lever moving outside the slot. The path change member may include: a cam which rotates by being pushed by the movement of the path change lever; a spring which positions the cam at a basic position; and a block wall which blocks the rotation of the cam. When the rotation of the cam is blocked by the block wall while the moving frame moves in a forward direction, not only the path change lever may move along an outer surface of the cam, but also the moving lever may enter the first branch slot from the reference slot. 
         [0014]    When the moving frame moves in the forward direction after the moving frame moves in a reverse direction and the moving lever re-enters the reference slot from the first branch slot, the moving lever may enter the second branch slot from the reference slot. 
         [0015]    The path change member may include: a change member which is movable above or below the guide plate; and a solenoid which moves the change member above or below the guide plate. When the change member moves above the guide plate, any one of the plurality of levers moves along an outer surface of the change member, so that movement paths of the plurality of levers may be changed. When the change member moves below the guide plate, the movement paths of the plurality of levers may not be changed. 
         [0016]    The slot may include a reference slot, a first branch slot which branches from one end of the reference slot, and a second branch slot. The reference slot may extend from one end thereof in a first direction. The first branch slot may include a first extension branch slot extending from the end of the reference slot in a first oblique direction and a second extension branch slot extending from an end of the first extension branch slot in a second direction opposite to the first direction. The second branch slot may extend from the end of the reference slot in the second direction. 
         [0017]    The first extension branch slot of the first branch slot may be bent. 
         [0018]    The plurality of levers may include a moving lever moving within the reference slot, the first branch slot, and the second branch slot. When the moving lever enters the first branch slot, the rotation frame may rotate at a predetermined angle in a rotation first direction. 
         [0019]    The guide plate may include a guide which forms the slot. The slot may include a reference slot, a first branch slot which branches from one end of the reference slot, and a second branch slot. The guide may include a reference guide forming the reference slot, a first guide forming the first branch slot, and a second guide forming the second branch slot. On the basis of the guide plate, a height of the first guide may be less than a height of the second guide, and one of the plurality of levers may pass over the first guide. 
         [0020]    The slot may include a reference slot, a first branch slot which branches from one end of the reference slot, and a second branch slot. The plurality of levers may include a moving lever which moves within the reference slot, the first branch slot, and a second branch slot. When the moving lever is located at an end of the first branch slot, the stapler may obliquely staple a bundle of sheets output from an image forming apparatus. When the moving lever is located within the second branch slot, the stapler may perform flat-stapling on a bundle of the sheets output from as mage forming apparatus. 
         [0021]    The reference slot may extend from one end thereof in a first direction. The first branch slot may include a first extension branch slot extending from the end of the reference slot in a first oblique direction and a second extension branch slot extending from an end of the first extension branch slot in a second direction opposite to the first direction. The second branch slot may extend from the end of the reference slot in the second direction. When the moving lever is located at the second extension branch slot of the first branch slot, the stapler may obliquely staple a bundle of the sheets output from an image forming apparatus. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0023]      FIG. 1  is a perspective view of a stapler apparatus according to an embodiment of the present invention; 
           [0024]      FIG. 2  is a plan view of a frame  100  shown in  FIG. 1 ; 
           [0025]      FIG. 3  is a plan view of a guide plate  200  shown in  FIG. 1 ; 
           [0026]      FIG. 4  shows a perspective view and a partial enlarged view of the guide plate  200  shown in  FIG. 3 ; 
           [0027]      FIGS. 5 to 6  show a state immediately after a path change lever  515  comes in contact with a cam  310 ; 
           [0028]      FIGS. 7 to 8  show a state where a path of the path change lever  515  is being changed by the cam  310 ; 
           [0029]      FIGS. 9 to 10  show that a moving lever  511  enters continuously a first branch slot  253  from a reference slot  251  by a rotation of a rotation frame  500  and then enters the end of the first branch slot  253 ; and 
           [0030]      FIGS. 11 to 12  show a state immediately after the moving lever  511  escapes from the first branch slot  253  and then enters the reference slot  251 . 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    Hereafter, an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. It is noted that the same reference numerals are used to denote the same elements throughout the drawings. In the following description of the present invention, the detailed description of known functions and configurations incorporated herein is omitted when it may make the subject matter of the present invention unclear. 
         [0032]    A stapler apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings. The stapler apparatus according to the embodiment of the present invention may be mounted within an image forming apparatus. 
         [0033]      FIG. 1  is a perspective views of a stapler apparatus according to an embodiment of the present invention.  FIG. 2  is a plan view of a frame  100  shown in  FIG. 1 .  FIG. 3  is a plan view of a guide plate  200  shown in  FIG. 1 .  FIG. 4  shows a perspective view and a partial enlarged view of the guide plate  200  shown in  FIG. 3 . 
         [0034]    Referring to  FIG. 1 , the frame  100  has a predetermined length in a first direction d 1 . Here, the first direction d 1  may be designated as the longitudinal direction d 1  of the frame  100  throughout this specification. 
         [0035]    The frame  100  may include, as shown in  FIG. 2 , a bottom plate  110  having a predetermined thickness. 
         [0036]    The bottom plate  110  has a slot  150 . The slot  150  may include a reference slot  151  and a plurality of slots  153  and  155 . The reference slot  151  is formed to extend in the first direction d 1 . The plurality of slots  153  and  155  branch from one end of the reference slot  151 . Here, though not shown in the drawings, the plurality of slots  153  and  155  may be formed not only on one end of the reference slot  151  but also on the other end of the reference slot  151 . 
         [0037]    At least the two slots  153  and  155  may be included. 
         [0038]    The plurality of slots  153  and  155  may include the first branch slot  153  and the second branch slot  155 . 
         [0039]    The first branch slot  153  includes a first extension branch slot  153 - 1  and a second extension branch slot  153 - 3 . The first extension branch slot  153 - 1  extends from the end of the reference slot  151  in a first oblique direction s 1 . The second extension branch slot  153 - 3  extends from the end of the first extension branch slot  153 - 1  in a second direction d 2  opposite to the first direction d 1 . Here, the first extension branch slot  153 - 1  may be formed straight. However, the shape of the first extension branch slot  153 - 1  is not limited to this. The first extension branch slot  153 - 1  may be formed to be bent. 
         [0040]    The second branch slot  155  extends from the end of the reference slot  151  in the second direction d 2 . Comparing the end of the first branch slot  153  with the end of the second branch slot  155  on the basis of the end of the reference slot  151 , the end of the first branch slot  153  and the end of the second branch slot  155  may be disposed at the same position. Otherwise, the end of the second branch slot  155  may be disposed longer than the first branch slot  153 . 
         [0041]    The first branch slot  153  and the second branch slot  155  may be formed not only on one end of the reference slot  151  but also on the other end of the reference slot  151  such that the first branch slot  153  and the second branch slot  155  formed on one end of the reference slot  151  may be symmetrical with the first branch slot  153  and the second branch slot  155  formed on the other end of the reference slot  151 . 
         [0042]    The frame  100  may include a side plate  130  shown in  FIG. 1 . The side plate  130  may be equipped with a rail  135 . Rollers of a moving frame  400  may be mounted on the rail  135 . 
         [0043]    The frame  100  may include a support bar  170 . The support bar  170  has a predetermined length and is disposed in the first direction d 1  or in the second direction d 2 . The support bar  170  is fastened to a fastener  430  of the moving frame  400  and, together with the rail  135 , allows the moving frame  400  to stably move. 
         [0044]    The guide plate  200  is disposed on the frame  100 . The guide plate  200  may be disposed on the bottom plate  110  of the frame  100 . 
         [0045]    The guide plate  200  includes a guide  230  disposed in the slot  150  of the frame  100 . That is, the guide  230  may be disposed to be inserted into the slot  150  of the frame  100  shown in  FIG. 2 . 
         [0046]    The guide  230  is disposed between the side plate  130  and the support bar  170  of the frame  100 . 
         [0047]    The guide  230  includes, as shown in  FIG. 3 , a slot  250  having a shape corresponding to the shape of the slot  150  of the frame  100  shown in  FIG. 2 . The size of the slot  250  is less than the size of the slot  150  of the frame  100  in order that the guide  230  is inserted into the slot  150  of the frame  100 . 
         [0048]    The slot  250  may include a reference slot  251  and a plurality of slots  253  and  255 . The reference slot  251  is formed to extend in the first direction d 1 . The plurality of slots  253  and  255  branch from one end of the reference slot  251 . Here, though not shown in the drawings, the plurality of slots  253  and  255  may be formed not only on one end of the reference slot  251  but also on the other end of the reference slobs  251 . 
         [0049]    The plurality of slots  253  and  255  may include at least two of the first branch slot  253  and the second branch slot  255 . 
         [0050]    The first branch slot  253  includes a first extension branch slot  253 - 1  and a second extension branch slot  253 - 3 . The first extension branch slot  253 - 1  extends from the end of the reference slot  251  in the first oblique direction s 1 . The second extension branch slot  253 - 3  extends from the end of the. first extension branch slot  253 - 1  in the second direction d 2  opposite to the first direction d 1 . Here, the first extension branch slot  253 - 1  may be formed straight. However, the shape of the first extension branch slot  253 - 1  is not limited to this. The first extension branch slot  253 - 1  may be formed to be bent. 
         [0051]    The second branch slot  255  extends from the end of the reference slot  251  in the second direction d 2 . Comparing the end of the first branch slot  253  with the end of the second branch slot  255  on the basis of the end of the reference slot  251 , the end of the first branch slot  253  and the end of the second branch slot  255  may be disposed at the same position. Otherwise, the end of the second branch slot  255  may be disposed longer than the first branch slot  253 . 
         [0052]    The guide  230  includes a reference guide  231 , a first guide  233 , and a second guide  235 . The reference guide  231  defines the reference slot  251 . The first guide  233  defines the first branch slot  253 . The second guide  235  defines the second branch slot  255 . On the basis of the top surface of the guide plate  200 , the height of the reference guide  231  may be the same as the height of the second guide  235  and may be different from the height of the first guide  233 . That is, the height of the reference guide  231  may be greater than the height of the first guide  233 . This intends to prevent the movement of a path change lever  515  shown in  FIG. 5  from being disturbed. Therefore, the path change lever  515  shown in  FIG. 5  passes over the first guide  233 . 
         [0053]    A path change member  300  changes directly the movement path of the path change lever  515  shown in  FIG. 5 , and thus, changes indirectly the movement path of a moving lever  511 . The path change member  300  changes the movement path of the path change lever  515 , and thus, causes the moving lever  511  to enter the first branch slot  253  from the end of the reference slot  251 . Here, unless the path change member  300  changes the movement path of the path change lever  515 , the moving lever  511  enters the second branch slot  255  from the end of the reference slot  251 . This will be described in detail later with reference to the drawings. 
         [0054]    The path change member  300  may include, as shown in  FIG. 4 , a cam  310 , a spring  330 , and a block wall  350 . 
         [0055]    The cam  310  includes a rotational axis  311 . The rotational axis  341  is installed adjacent to the reference guide  231 . The cam  310  is, as shown in  FIG. 5 , disposed on the movement path of the path change lever  515 . 
         [0056]    The cam  310  further includes a first outer surface  313  and a second outer surface (not shown). As shown in  FIG. 5 , the first outer surface  313  comes in contact with the path change lever  515 . The movement path of the path change lever  515  may be changed along the first outer surface  313 . The first outer surface  343  may be curved. The second outer surface (not shown) comes in contact with the block wall  350 . When the second outer surface (not shown) comes in contact with the block wall  350 , the cam  310  is not able to rotate any more along the rotational axis  311 . 
         [0057]    As long as a separate external force is not provided, the spring  330 , together with the rotational axis  311 , positions the cam  310  at a predetermined position (hereafter, referred to as a basic position). 
         [0058]    The block wall  350  blocks, as shown in  FIG. 7 , the rotation of the cam  310  caused by the path change lever  515 . 
         [0059]    The block wall  350  may be disposed on the rotation path of the cam  310  and may be disposed between the reference guide  231  and the first guide  233 . 
         [0060]    The block wall  350  may be disposed below the movement path of the path change lever  515  shown in  FIG. 5 . Therefore, the path change lever  515  passes over the block wall  350  without directly contacting the block wall  350 . On the basis of the top surface of the guide plate  200 , the height of the block wall  350  may be the same as or greater than the height of the first guide  233 . 
         [0061]    The path change member  300  is not limited to the cam  310 , the spring  330 , and the block wall  350 . For another example, the path change member  300  may include a change member (not shown) and a solenoid (not shown). The change member (not shown) may be installed at the position of the cam  310  and may move above or below the guide plate  200  by the solenoid (not shown). When the change member (not shown) has moved above the guide plate  200 , the movement path of the path change lever  515  is changed. When the change member (not shown) has moved below the guide plate  200 , the movement path of the path change lever  515  is not changed. 
         [0062]    The moving frame  400  performs a reciprocating motion on the guide plate  200 . The moving frame  400  performs a reciprocating motion in the first direction d 1  or in the second direction d 2 . 
         [0063]    Rollers which moves along the rail  135  mounted on the side plate  130  of the frame  100  may be mounted on the moving frame  400 . 
         [0064]    The fastener  430  which is fastened to the support bar  170  of the frame  100  may be mounted on the moving frame  400 . The fastener  430  has a structure surrounding a portion of the support bar  170  and moves along the support bar  170  by the movement of the moving frame  400 . 
         [0065]    A rotation frame  500  is installed on the moving frame  400  and moves with the moving frame  400 . 
         [0066]    A stapler  600  is installed and fixed to the rotation frame  500 . The stapler  600  is moved by the moving frame  400  and is rotated by the rotation frame  500 . The stapler  600  staples at a predetermined position in accordance with an external control command. 
         [0067]    Here, in  FIGS. 1 to 12 , the stapler  600  may be a punch which punches a bundle of sheets or a saddle stitcher which saddle-stitches a bundle of sheets. 
         [0068]    A plurality of levers  511 ,  513 , and  515  for rotating the stapler  600  at a predetermined angle are, as shown in  FIG. 5 , mounted on the rotation frame  500 . Specifically, the plurality of levers  511 ,  513 , and  515  are fixed and mounted on the bottom surface of the frame  500 . For reference,  FIG. 5  shows that the rotation frame  500  has been removed. 
         [0069]    The plurality of levers  511 ,  513 , and  515  include, as shown in  FIG. 5 , the moving lever  511 , an axis lever  513 , and the path change lever  515 . 
         [0070]    The moving lever  511  moves within the slot  250  of the guide  230 . Specifically, the moving lever  511  may be inserted into the slot  250  and move within the reference slot  251 , the first branch slot  253 , and the second branch slot  255 . In other words, the moving lever  511  may move within the reference slot  251 , the first branch slot  253 , and the second branch slot  255  in the first direction d 1 , in the second direction d 2 , and in the first oblique direction s 1 . 
         [0071]    The moving lever  511  is guided by the reference guide  231 , the first guide  233 , and the second guide  235 . A roller  511   a  may be mounted on the moving lever  511 . The roller  511   a  reduces friction between the moving lever  511  and the reference guide  231 , the first guide  233 , and the second guide  235 . Accordingly, the moving lever  511  is able to move more smoothly. 
         [0072]    The axis lever  513  is disposed apart from the moving lever  511  at a predetermined interval, The axis lever  513 , together with the moving lever  511 , moves within the slot  250  of the guide  230 . Here, unlike the moving lever  511 , the axis lever  513  cannot move to the first branch slot  253  and can move within the reference slot  251  and the second branch slot  255 . That is, the axis lever  513  can move within the reference slot  251  and the second branch slot  255  in the first direction d 1  and in the second direction d 2 . 
         [0073]    The axis lever  513  is guided by the reference guide  231  and the second guide  235 . A roller  515   a  may be mounted on the axis lever  513 . 
         [0074]    The axis lever  513  functions as a rotational axis of the rotation frame  500 . Specifically, when the moving lever  511  enters the first branch slot  253 , the rotation frame  500  rotates, as shown in  FIGS. 8 and 10 , clockwise (a first rotation direction, C 1 ) at a predetermined angle. Here, the rotation frame  500  rotates about the axis lever  513 . Here, the moving frame  400  does not rotate. 
         [0075]    The moving lever  511  may function as the axis lever, and the axis lever  513  may function as the moving lever. This case occurs when the moving frame  400  moves to the other end of the reference slot  251 . Therefore, it should be understood that the moving lever  511  and the axis lever  513  are relative rather than absolute. 
         [0076]    The path change lever  515  is disposed apart from the moving lever  511  and the axis lever  513  at a predetermined interval and is disposed on the guide plate  200 . 
         [0077]    Unlike the moving lever  511  and the axis lever  513 , the path change lever  515  is not disposed within the slot  250  of the guide  230 . The path change lever  515  is able to move above the first branch slot  253  and does not move within the first branch slot  253 . 
         [0078]    The path change lever  515  moves in parallel with the axis lever  513 . That is, the path change lever  515  may move in the first direction d 1  and in the second direction d 2 . 
         [0079]    The path change member  300  is disposed on the movement path of the path change lever  515 . The movement path of the path change lever  515  is changed by the contact of the path change lever  515  with the path change member  300 . That is, the path change lever  515  moves in the first oblique direction s 1  by the path change member  300 . As the path change lever  515  moves in the upper oblique direction s 1 , the moving lever  511  enters the first branch slot  253  from the reference slot  251 . 
         [0080]    If the path change lever  515  does not contact the path change member  300 , the moving lever  511  does not enter the first branch slot  253  and enters the second branch slot  255 . 
         [0081]    Hereinafter, a method in which the moving lever  511  enters the first branch slot  253  from the reference slot  251  will be described in detail with reference to  FIGS. 5 to 10 . 
         [0082]      FIGS. 5 to 6  show a state immediately after the path change lever  515  comes in contact with the cam  310 . 
         [0083]    Referring to  FIGS. 5 to 6 , when the moving frame  400  moves in the second direction d 2 , the moving lever  511 , the axis lever  513 , and the path change lever  515  which have been mounted on the rotation frame  500  move together in the second direction d 2 . 
         [0084]    When the cam  310  fixed to the basic position by the rotational axis  311  and the spring  330  contacts the path change lever  515  (namely, when the path change lever  515  comes in contact with the first outer surface  313  of the cam  310 ) while the path change lever  515  moves in the second direction d 2 , the path change lever  515  starts to push cam  310 . Here, stapler  600  is, as shown in  FIG. 6 , directed in a third direction d 3  perpendicular to the second direction d 2  because the rotation frame  500  is not rotating. 
         [0085]      FIGS. 7 to 8  show a state where the path of the path change lever  515  is being changed by the cam  310 . 
         [0086]    Referring to  FIGS. 7 to 8 , when the moving frame  400  moves continuously in the second direction d 2 , the path change lever  515  moves in the second direction d 2  while pushing the cam  310 . Here, the cam  310  rotates along the rotational axis  311  before the cam  310  contacts the block wall  350  shown in  FIG. 4  by being pushed by the path change lever  515 . When the cam  310  cannot rotate any more by the block wall  350 , the path change lever  515  moves along the first outer surface  313  in a state of contacting the first outer surface  313  of the cam  310 . At the moment when the path change lever  515  moves along the first outer surface  313 , the movement path of the path change lever  515  is changed and the rotation frame  500  rotates clockwise (C 1 ) slightly about the axis lever  513 . Due to the rotation of the rotation frame  500 , the moving lever  511  enters the first branch slot  253  from the reference slot  251 , and, as shown in  FIG. 8 , the stapler  600  rotates clockwise (C 1 ) slightly in conjunction with the rotation frame  500 . 
         [0087]      FIGS. 9 to 10  show that the moving lever  511  enters continuously the first branch slot  253  from the reference slot  251  by the rotation of the rotation frame  500  and then enters the end of the first branch slot  253 . 
         [0088]    Referring to  FIGS. 9 to 10 , when the moving lever  511  enters the first branch slot  253 , the moving lever  511  moves along the first branch slot  253  in the first oblique direction  1 , and then moves in the second direction d 2  by the movement of the moving frame  400  in the second direction d 2 . During this process, the stapler  600  further rotates clockwise (C 1 ), and then becomes the state of  FIG. 10 . When the stapler  600  is in the state of  FIG. 10 , it is possible to obliquely staple a corner of a bundle of sheets P output from the image forming apparatus. 
         [0089]    In the state shown in  FIG. 10 , it can be designated as an “automatic staple mode” because a bundle of sheets P output from the image forming apparatus are stapled. 
         [0090]    A method in which the moving lever  511  enters the second branch slot  255  will be described in detail with reference to  FIGS. 11 to 12 . 
         [0091]      FIGS. 11 to 12  show a state immediately after the moving lever  511  escapes from the first branch slot  253  and then enters the reference slot  251 . 
         [0092]    In order that the moving lever  511  enters the second branch slot  255 , the processes of  FIGS. 5 and 7  are sequentially performed. However, after that, the process may not reach the state shown in  FIG. 9 . 
         [0093]    For example, as described in  FIG. 7 , after the moving lever  511  enters the first branch slot  253 , the moving lever  511  moves to the first branch slot  253  by a predetermined distance due to the change of the movement path of the path change lever  515 . Here, the predetermined distance corresponds to a distance by which the path change lever  515  passes by the cam  310  and then the cam  310  is able to move to the basic position by the spring  330 . 
         [0094]    Immediately after the moving lever  511  moves within the first branch slot  253  by a predetermined distance, the moving frame  400  retreats in the first direction d 1  opposite to the second direction d 2 . Due to the retreat of the moving frame  400 , the moving lever  511  returns to the reference slot  251  from the first branch slot  253  and then becomes the state of  FIGS. 11 to 12 . In the state of  FIGS. 11 to 12 , the moving lever  511  is not disposed on the first outer surface  313  of the cam  310  but on the second outer surface (not shown). The stapler  600  rotates counterclockwise (a second rotation direction, C 2 ) and is directed in the third direction d 3 . 
         [0095]    In the state of  FIGS. 11 to 12 , when the moving frame  400  moves in the second direction d 2 , the movement path of the path change lever  515  is not changed and the path change lever  515  moves in the second direction d 2 , i.e., the movement direction of the moving frame  400  because the path change lever  515  is not affected by the cam  310 . Also, the moving lever  511  enters the second branch slot  255  from the reference slot  251 . Here, when the moving lever  511  enters the second branch slot  255  from the reference slot  251  and then stops, the stapler  600  can staple at the moment when the moving lever  511  stops. The moving lever  511  may stops at least twice. In the state where the stapler  600  is, as shown in  FIG. 12 , directed in the third direction d 3 , a bundle of sheets can be flat-stapled at least twice by the stapler  600 . As such, the stapler apparatus according to the embodiment of the present invention is able not only to obliquely staple a corner of a bundle of sheets, but also to perform the flat-stapling. 
         [0096]    While the embodiment of the present invention has been described with reference to the accompanying drawings, these are just examples and do not limit the present invention. Further, the present invention may be changed and modified in various ways, without departing from the essential features of the present invention, by those skilled in the art. For example, the components described in detail in the embodiments of the present invention may be modified. Further, differences due to the modification and application should be construed as being included in the scope and spirit of the present invention, which is described in the accompanying claims.