Patent Publication Number: US-9845218-B2

Title: Folding device, post-processing device and image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the U.S. National Phase under 35. U.S.C. §371 of International Application PCT/JP2013/050590, filed Jan. 15, 2013, which claims priority to Japanese Patent Application No. 2012-066355, filed Mar. 22, 2012, and Japanese Patent Application No. 2012-066356, filed Mar. 22, 2012. The disclosures of the above-described applications are hereby incorporated by reference in their entirety. The International Application was published under PCT Article 21(2) in a language other than English. 
     TECHNICAL FIELD 
     The present invention relates to a folding device that can fold a sheet member such as a sheet-like image formation target material, a post processing device, and an image forming apparatus provided with the post processing device. 
     BACKGROUND ART 
     Conventionally, a post processing device that can be connected to an image forming apparatus main body of a copy machine, a multi-function peripheral and the like has existed. The post processing device performs predetermined post processing on a sheet (or a stack of sheets) having been discharged from the image forming apparatus main body. As the post-processing, punching processing on the sheet, staple processing on the stack of sheets, and processing on the sheet (the stack of sheets) can be exemplified. 
     The post processing device with a folding function has a blade and a pair of rollers. The blade is brought into contact with a sheet (a stack of sheets) to fold. The pair of rollers pinches and receives the sheet (the stack of sheets) thus folded as well as the blade to thereby make a fold. 
     Here, in a folding process, the blade may be loaded and damaged with a certain type and number of sheets (stacks of sheets). 
     In order to address this, an image forming apparatus has been proposed that is provided with a clutch means which drives a pair of rollers to be rotatable in a state in which a blade and a sheet (a stack of sheets) are inserted between the rollers (refer to Patent Document 1). 
     In addition, an image forming apparatus has been proposed that is configured to be capable of adjusting a crimping force between the rollers in a state in which a blade and a sheet (a stack of sheets) are inserted between the rollers (refer to Patent Document 2). 
     Patent Document 1: Japanese Unexamined Patent Application Publication No. 2008-184324 
     Patent Document 2: Japanese Unexamined Patent Application Publication No. 2008-247535 
     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     However, the blade may be damaged in the image forming apparatus disclosed in Patent Document 1 or Patent Document 2. In this case, the post processing device stops the processing operation in a state in which the blade is inserted between the rollers. A load of an operation of bringing this state back to a normal state is extremely high. 
     The present invention is aimed at providing a post processing device that suppresses damage of the folding member and that can reduce an operator&#39;s burden in a case of failure. 
     In addition, the present invention aims at providing an image forming apparatus provided with the post processing device. 
     Means for Solving the Problems 
     The present invention relates to a folding device including a conveying path, a placement portion, a through portion, a first folding member, a second folding member, a driving mechanism, a rotational position detecting mechanism, a signal receiving unit, and a rotational drive control unit. 
     The conveying path is configured to be capable of conveying a sheet member in a predetermined conveying direction. 
     The placement portion constitutes a part of the conveying path and has a placement face on which the sheet member can be placed. 
     The through portion is formed on the placement portion and formed to be through from the placement face side to an opposite face on an opposite side of the placement face. 
     The first folding member is arranged on the opposite face side in the placement portion, to be movable between an initial position where a tip end part thereof is positioned at a predetermined position on the opposite face side and a protruded position where the tip end part penetrates the through portion and is positioned at a predetermined position on the placement face side, the first folding member folding and moving the sheet member by moving from the initial position to the protruded position in a state in which the sheet member is placed thereon. 
     The second folding member is arranged on the placement face side of the placement portion, and pinches and receives the sheet member thus folded as well as the first folding member in a state in which the first folding member is positioned at the protruded position. 
     The driving mechanism includes a rotational driving unit that can output a rotational driving force and a rotating member that is rotated by the rotational driving force from the rotational driving unit, the driving mechanism making the first folding member reciprocate between the initial position and the protruded position. 
     The rotational position detecting mechanism detects a rotational position of the rotating member and outputs rotational position information. 
     The signal receiving unit receives a predetermined signal. 
     The rotational drive control unit receives the rotational position information from the rotational position detecting mechanism. 
     The driving mechanism can output the rotational driving force. The driving mechanism includes a converting unit that converts a rotational motion of the rotating member into a reciprocating motion. 
     The rotational driving unit can reverse a direction of the rotational drive. 
     The rotating member is directly or indirectly connected to the rotational driving unit. 
     The rotational drive control unit, when the signal receiving unit receives the predetermined signal, determines whether the first folding member is in a state of moving from the initial position to the protruded position or the first folding member is in a state of moving from the protruded position to the initial position based on the rotational position information. The rotational drive control unit, in a case in which the first folding member is determined to be in the state of moving from the initial position to the protruded position, controls the rotational driving unit to reverse the direction of rotational drive, and in a case in which the first folding member is determined to be in the state of moving from the protruded position to the initial position, controls the rotational driving unit to maintain the direction of rotational drive. 
     The present invention relates to a folding device including a conveying path, a placement portion, a through portion, a first folding member, a second folding member, a driving mechanism, a rotational position detecting mechanism, a rotational load monitoring unit, and a rotational drive control unit. 
     The conveying path is configured to be capable of conveying a sheet member in a predetermined conveying direction. 
     The placement portion constitutes a part of the conveying path and has a placement face on which the sheet member can be placed. 
     The through portion is formed on the placement portion and formed to be through from the placement face side to an opposite face on an opposite side of the placement face. 
     The first folding member is arranged on the opposite face side in the placement portion, to be movable between an initial position where a tip end part thereof is positioned at a predetermined position on the opposite face side and a protruded position where the tip end part penetrates the through portion and is positioned at a predetermined position on the placement face side, the first folding member folding and moving the sheet member by moving from the initial position to the protruded position in a state in which the sheet member is placed thereon. 
     The second folding member is arranged on the placement face side of the placement portion, and pinches and receives the sheet member thus folded as well as the first folding member in a state in which the first folding member is positioned at the protruded position. 
     The driving mechanism includes a rotational driving unit that can output a rotational driving force and a rotating member that is rotated by the rotational driving force from the rotational driving unit, the driving mechanism making the first folding member reciprocate between the initial position and the protruded position. 
     The rotational position detecting mechanism detects a rotational position of the rotating member and outputs rotational position information. 
     The rotational load monitoring unit detects a rotational load generated in the rotational driving unit and determines whether the rotational load is at least a predetermined load. 
     The rotational drive control unit receives the rotational position information from the rotational position detecting mechanism. 
     The driving mechanism can output the rotational driving force. The driving mechanism includes a converting unit that converts a rotational motion of the rotating member into a reciprocating motion. 
     The rotational driving unit can reverse a direction of the rotational drive. 
     The rotating member is directly or indirectly connected to the rotational driving unit. 
     The rotational drive control unit, when the rotational load monitoring unit determines that the rotational load is at least the predetermined load, determines whether the first folding member is in a state of moving from the initial position to the protruded position or the first folding member is in a state of moving from the protruded position to the initial position based on the rotational position information. The rotational drive control unit, in a case in which the first folding member is determined to be in the state of moving from the initial position to the protruded position, controls the rotational driving unit to reverse the direction of rotational drive, and in a case in which the first folding member is determined to be in the state of moving from the protruded position to the initial position, controls the rotational driving unit to maintain the direction of rotational drive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram for explaining an overall configuration of a copy machine of a first embodiment; 
         FIG. 2  is a diagram explaining a configuration of a folding processing unit that composes a post processing device; 
         FIG. 3A  is a diagram explaining a cam mechanism that composes the folding processing unit; 
         FIG. 3B  is a diagram explaining a cam mechanism that composes the folding processing unit; 
         FIG. 4A  is a block diagram showing a functional configuration in a copy machine (post processing device) of the first embodiment; 
         FIG. 4B  is a diagram explaining a table stored in a storage unit; 
         FIG. 5  is a flow chart explaining an operation in the folding processing unit in the copy machine of the first embodiment; 
         FIG. 6  is a diagram explaining a state in which a blade is positioned at an initial position; 
         FIG. 7  is a diagram explaining a state in which the blade is moving from the initial position to a protruded position; 
         FIG. 8  is a diagram explaining a state in which the blade is positioned at the protruded position; 
         FIG. 9  is a diagram explaining a state in which the blade has been moved from the protruded position to the initial position side; 
         FIG. 10  is a diagram explaining a state in which the blade has been brought back to the initial position; 
         FIG. 11  is a diagram explaining a state in which the blade has been further moved from the position of  FIG. 7  to the protruded position side; 
         FIG. 12  is a diagram explaining a state in which the blade has been further moved from the position of  FIG. 8  to the initial position side; 
         FIG. 13  is a block diagram showing a functional configuration in a copy machine (post processing device) of a second embodiment; 
         FIG. 14  is a flow chart explaining an operation in the folding processing unit in the copy machine of the second embodiment; 
         FIG. 15A  is a diagram explaining a crank mechanism that composes the folding processing unit in another embodiment; 
         FIG. 15B  is a diagram explaining an operation of the crank mechanism; 
         FIG. 15C  is a diagram explaining an operation of the crank mechanism; and 
         FIG. 15D  is a diagram explaining an operation of the crank mechanism. 
     
    
    
     EXPLANATION OF REFERENCE NUMERALS 
     
         
         
           
               1  Copy machine (Image forming apparatus) 
               2  Copy machine main body (Image forming apparatus main body) 
               100  Post processing device 
               110  Second paper conveying unit (Conveying unit) 
               201  Sheet placement member (Placement portion) 
               204  Through portion 
               222  Blade member (First folding member) 
               223  Pair of folding rollers (Second folding member) 
               300  Driving mechanism 
               310  Cam mechanism (Converting unit) 
               350  Rotating member 
               360  Rotational drive unit 
               365  Signal receiving unit 
               366  Rotational load monitoring unit 
               370  Rotational drive control unit 
               400  Rotational position detecting mechanism 
             HP Initial position 
             TP Protruded position 
             T Paper (Image formation target material, sheet member) 
           
         
       
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First Embodiment 
     A copying machine  1  according to a first embodiment of an image forming apparatus of the present invention will be described hereafter making reference to the figures. Firstly, the overall configuration of the copying machine  1  will be described.  FIG. 1  is a diagram for explaining an overall configuration of a copy machine of a first embodiment. 
     A copy machine  1  is provided with a copy machine main body  2  (image forming apparatus main body) and a post processing device  100 . The copy machine main body  2  (image forming apparatus main body) forms a toner image onto paper T. The post processing device  100  is disposed on a paper discharging side of the copy machine main body  2 . The post processing device  100  performs punching processing, staple processing, and fold processing on the paper (image formation target material, sheet member) T on which a toner image is formed. 
     The copy machine main body  2  includes an original conveying unit  10 , an original scanning unit  20 , a first paper conveying unit  30 , a toner image forming unit  40 , a transfer unit  50 , and a fusing unit  60 . 
     The original conveying unit  10  is an ADF (auto document feeder), and includes an original placement portion  11 , a first roller  12 , a guide  13 , a pair of timing rollers  14 , and an original discharging unit  15 . The first roller  12  supplies an original G mounted on the original placement portion  11  sheet by sheet to the pair of timing rollers  14 . The pair of timing rollers  14  conveys the original G or stops the conveyance of the original G in order to make the timing of the scanning of the original G by the original scanning unit  20  coincide with the timing of supplying the original G to the position for scanning of the original G by the original scanning unit  20  (position at which the guide  13  is disposed). The guide  13  introduces the conveyed original G to the first scanning surface  21   a  as described above. The original discharging unit  15  discharges an original G read by the original scanning unit  20  (passed through the guide  13 ) to the outside of the copy machine main body  2 . 
     An original collection unit  16  is formed on an outer side of the copy machine main body  2  in the original discharging unit  15 . An original G discharged from the original discharging unit  15  is stacked and collected in the original collection unit  16 . 
     The original scanning unit  20  includes a first scanning surface  21   a  and a second scanning surface  22   a . The first scanning surface  21   a  is formed along the upper surface of a first contact glass  21 . The first contact glass  21  is arranged to oppose the guide  13 . The first scanning surface  21   a  is a face that scans an original G. The second scanning surface  22   a  is disposed adjacently to the first scanning surface  21   a . The second scanning surface  22   a  is disposed along the majority of a right side of the first scanning surface  21   a , in a configuration shown in  FIG. 1 . The second scanning surface  22   a  is used when scanning an original G without using the original conveying unit  10 . The second scanning surface  22   a  is formed along the upper surface of a second contact glass  22 . The original G is placed on the second contact glass  22 . The second scanning surface  22   a  is a face that scans the original G. 
     The original scanning unit  20  is provided with an illumination unit  23 , a first mirror  24 , a second mirror  25 , a third mirror  26 , an imaging lens  27 , and an image capture unit  28 . The illumination unit  23 , the first mirror  24 , the second mirror  25 , the third mirror  26 , the imaging lens  27 , and the image capture unit  28  are provided in an inner portion of the copy machine main body  2 . The illumination unit  23  and the first mirror  24  move respectively in a sub-scanning direction X. The first mirror  25  and the third mirror  26  are disposed on the left side of the illumination unit  23  and the first mirror  24  in  FIG. 1 . Furthermore, the second mirror  25  and the third mirror  26  respectively move in the sub-scanning direction X while maintaining a fixed distance (optical path length) from the first scanning surface  21   a  or the second scanning surface  22   a  to the image capture unit  28 . The distance (optical path length) from the first scanning surface  21   a  or the second scanning surface  22   a  to the image capture unit  28  is a distance passing through the first mirror  24 , the second mirror  25 , the third mirror  26 , and the imaging lens  27 . 
     The illumination unit  23  is a light source that illuminates light onto the original G. The first mirror  24 , the second mirror  25 , and the third mirror  26  are mirrors that maintain a fixed optical path length while introducing light reflected by the original G to the imaging lens  27 . The imaging lens  27  images light that is incident from the third mirror  26  onto the image capture unit  28 . The image capture unit  28  is provided with a plurality of imaging devices. The plurality of imaging devices is arrayed along a horizontal scanning direction (a direction that is orthogonal to the sub-scanning direction X). The imaging devices are devices for obtaining image data based on a focused light image by converting the incident light to an electrical signal, and for example may be a charge coupled device (CCD) or the like. 
     The first paper conveying unit  30  includes a second feed roller  31 , a third feed roller  32 , a pair of registration rollers  33 , a switching unit  39 , a first paper discharging unit  34 , and a second paper discharging unit  38 . The second feed roller  31  supplies the paper T contained in a paper feeding cassette  36  to the transfer unit  50 . The third feeding roller  32  supplies the paper T placed on the manual feed tray  37  to the transfer unit  50 . The pair of registration rollers  33  conveys the paper T or stops the conveyance of the paper T in order to make the timing of the forming of a toner image on the transfer unit  50  coincide with the timing of supplying the paper T to the transfer unit  50 . The pair of registration rollers  33  corrects skew (inclination of the supplied sheet) of the paper T. The switching unit  39  reverses a conveying direction of the paper T so as to convey the paper T having been discharged from the fusing unit  60  to one of the first paper discharging unit  34  and the second paper discharging unit  38 . The first paper discharging unit  34  and the second paper discharging unit  38  discharges the paper T having a toner image fused thereonto to an external side of the copy machine main body  2 . A discharged paper collection unit  35  is formed in the first paper discharging unit  34 , on an external side of the copy machine main body  2 . The paper T discharged from the first paper discharging unit  34  is stacked and collected in the discharged paper collection unit  35 . 
     The toner image forming unit  40  includes a photosensitive drum  41 , a charging member  42 , a laser scanning unit  43 , a developing unit  44 , a cleaning unit  45 , a toner cartridge  46 , a primary transfer roller  47 , an intermediate transfer belt  48 , and a counter roller  49 . 
     The photosensitive drum  41  ( 41   a ,  41   b ,  41   c ,  41   d ) functions as a photosensitive body or an image supporting body to form respective toner images of black, cyan, magenta and yellow. The charging member  42 , a laser scanner unit  43 , a developing unit  44 , and a cleaning unit  45  are disposed in order from upstream to downstream along the rotation direction of the photosensitive drum  41  in the periphery of each photosensitive drum  41   a ,  41   b ,  41   c , and  41   d . The charging member  42  applies a charge to the surface of the photosensitive drum  41 . The laser scanner unit  43  is disposed away from a surface of the photosensitive drum  41 . The laser scanning unit  43  scans and exposes the surface of the photosensitive drum  41  based on the image data related to the original G having been read by the original scanning unit  20 . In this manner, a charge on the exposed portion on the surface of the photosensitive drum  41  is removed to thereby form an electrostatic latent image. The developing unit  44  attaches toner to the electrostatic latent image formed on the surface of the photosensitive drum  41  to thereby form a toner image. After the surface of the photosensitive drum  41  is destaticized by a destaticizing device (not shown), the cleaning unit  45  removes residual toner and the like from the surface of the photosensitive drum  41  having been destaticized. 
     The toner cartridge  46  contains respective colors of toner supplied to the developing unit  44 . The toner cartridge  46  and the developing unit  44  are connected by a toner supply passage (not shown). 
     The primary transfer rollers  47  ( 47   a ,  47   b ,  47   c ,  47   d ) are respectively disposed opposite each photosensitive drum  41   a ,  41   b ,  41   c ,  41   d  in the intermediate transfer belt  48 . The intermediate transfer belt  48  is a belt passing through the toner image forming unit  40  and the transfer unit  50 . A part of the intermediate transfer belt  48  is pinched between each photosensitive drum  41   a ,  41   b ,  41   c ,  41   d  and each primary transfer roller  47   a ,  47   b ,  47   c ,  47   d . Primary transfer of a toner image formed on the surface of each photosensitive drum  41   a ,  41   b ,  41   c ,  41   d  is executed onto the part of the intermediate transfer belt  48 . The counter roller  49  is disposed on an inner side of the annular intermediate transfer belt  48 . The counter roller  49  is a drive roller that propels the intermediate transfer belt  48  in the direction of an arrow A shown in  FIG. 1 . 
     The transfer unit  50  includes a secondary transfer roller  51 . The secondary transfer roller  51  is disposed on an opposite side of the counter roller  49  in the intermediate transfer belt  48 . The secondary transfer roller  51  and the counter roller  49  pinch the part of the intermediate transfer belt  48 . The secondary transfer roller  51  executes secondary transfer of the toner image, which has been subjected to primary transfer onto the intermediate transfer belt  48 , onto the paper T. 
     The fusing unit  60  includes a heating rotating body  61  and a pressuring rotating body  62 . The heating rotating body  61  and the pressuring rotating body  62  pinch the paper T that includes the toner image having been subjected to the secondary transfer, to thereby melt and pressurize the toner, and fuse that toner onto the paper T. 
     The post processing device  100  is configured to be connectable to the copy machine main body  2 . The post processing device  100  is provided with a second paper conveying unit  110  (conveying path), a punching unit  120 , a stapling unit  130 , and a folding unit  190 . 
     The second paper conveying unit  110  has a conveying path  110   a , a conveying path  110   b , a conveying path  110   c , a conveying path  110   d , and a conveying path  110   e . The second paper conveying unit  110  is configured to be capable of conveying the sheet-like paper T in a predetermined conveying direction. 
     The conveying path  110   a  is provided with an introduction unit  111 , a branching guide  112 , and a first discharging unit  113 . 
     The introduction unit  111  introduces the paper T having been discharged from the second paper discharging unit  38  of the copy machine main body  2  into the post processing device  100 . The introduction unit  111  conveys the paper T having been introduced into the post processing device  100  to the punching unit  120 . 
     The branching guide  112  switches the conveying direction of the paper T having been discharged from the punching unit  120  to one of the first discharging unit  113  and the stapling unit  130 . 
     The first discharging unit  113  discharges the paper T having been discharged from the punching unit  120  and the paper T having been discharged from the stapling unit  130 , from the post processing device  100 . 
     A main tray  114  is disposed in the first discharging unit  113 , on an external side of the post processing device  100 . The paper T having been discharged from the first discharging unit  113  is stacked and collected in the main tray  114 . 
     The punching unit  120  performs a series of processes relating to punching processing. The punching processing is processing for forming a hole for binding the paper T at a predetermined position on the paper. 
     The stapling unit  130  is a unit for binding the paper T by means of a staple (stapling processing). The stapling unit  130  is provided with a paper receiving tray  131 , a receiving unit  132 , a staple processing unit  133 , and a conveying roller  134 . Here, the paper receiving tray  131 , the receiving unit  132  and the conveying roller  134  compose a part of the conveying path  110   c.    
     The paper receiving tray  131  temporarily retains a plurality of sheets of paper T having been introduced from the punching unit  120  by switching of the branching guide  112 . 
     The receiving unit  132  receives and retains a lower end part of the paper T having been introduced to the paper receiving tray  131 . 
     The stapling processing unit  133  moves to the vicinity of an edge part or a central part of the paper T being retained on the paper receiving tray  131  and performs stapling processing in the vicinity of the edge part or the central part of the paper T. 
     The conveying roller  134  conveys a stack of paper having been stapled (saddle stitched) in the vicinity of the central part thereof from the paper receiving tray  131  to the folding processing unit  190 . 
     The folding processing unit  190  double-folds the stack of paper having been, for example, saddle stitched, from the vicinity of the central part (folding processing). The folding processing unit  190  is described in detail hereafter. 
     The folding processing unit  190  in the post processing device  100  (folding device) according to the present embodiment is described with reference to  FIGS. 2 to 3B .  FIG. 2  is a diagram explaining a configuration of a folding processing unit that composes a post processing device.  FIG. 3A  is a diagram explaining a cam mechanism that composes the folding processing unit.  FIG. 3B  is a diagram explaining a cam mechanism that composes the folding processing unit. In the following description, “paper T” shall be considered to include a stack of the paper T, for the sake of convenience. 
     As shown in  FIG. 1 , the folding processing unit  190  is disposed on a downstream side of the second paper conveying unit  110 . Into the folding processing unit  190 , for example, a sheet of paper T or a stack of paper T having been stapled is introduced. The folding processing unit  190  performs the folding processing on the paper T having been introduced. And then, the folding processing unit  190  discharges the paper T thus folded to a lower discharging tray  145 . The lower discharging tray  145  is provided in a lower part of a side face of the post processing device  100 . 
     The folding processing unit  190  is provided with: a sheet introduction path  200 ; a sheet placement member  201  (placement portion) with a sheet placement face  202  (placement face); a through portion  204 ; an alignment portion  210 ; a pushing member  211 ; a receiving member  212 ; a folding portion  220 ; and a second discharging unit  230 . 
     The sheet introduction path  200  is a path for introducing the paper T, having been conveyed on the conveying path, into the folding processing unit  190 . As shown in  FIG. 1 , the sheet introduction path  200  is disposed in an upper part of a right side of the folding processing unit  190 . The sheet introduction path  200  conveys the paper T toward the sheet placement member  201  (sheet placement face  202 ). 
     The sheet placement member  201  composes a part of the conveying path  110   d  (second paper conveying unit  110 ). The sheet placement member  201  includes the sheet placement face  202  on which the sheet-like paper T can be placed. 
     The sheet placement member  201  is provided with the upstream sheet placement member  201 A, the downstream sheet placement member  201 B, and the through portion  204 . 
     The upstream sheet placement member  201 A includes an upstream sheet placement face  202 A. The downstream sheet placement member  201 B includes a downstream sheet placement face  202 B. 
     The upstream sheet placement member  201 A and the downstream sheet placement member  201 B are members on which the paper T is placed for performing the folding processing on the paper T having been introduced. 
     The upstream sheet placement member  201 A and the downstream sheet placement member  201 B are disposed to extend from an upper right side to a lower left side of an inner part of the folding processing unit  190 . The upstream sheet placement member  201 A and the downstream sheet placement member  201 B are disposed across the through portion  204  (described later). 
     The upstream sheet placement member  201 A and the downstream sheet placement member  201 B are composed of plate-like members. The upstream sheet placement member  201 A and the downstream sheet placement member  201 B are disposed in line in the sheet conveying direction. 
     The paper T placed on the upstream sheet placement member  201 A and the downstream sheet placement member  201 B is fed into a first nip N 1  of the pair of folding rollers  223  by a blade member  222  (described later in detail) penetrating the through portion  204 . 
     The through portion  204  is formed to penetrate the sheet placement face  202  to an opposite face  203  side that is on an opposite side of the sheet placement face  202 . 
     The through portion  204  is disposed between the upstream sheet placement member  201 A and the downstream sheet placement member  201 B. 
     The through portion  204  is a through hole through which the blade member  222  penetrates. 
     The alignment portion  210  is provided to align the paper T on the upstream sheet placement member  201 A and the downstream sheet placement member  201 B, so as to accurately perform the folding processing on the paper T having been introduced. The alignment portion  210  aligns the paper T in a direction parallel to the conveying direction of the paper T (left downward direction in  FIG. 1 ) and in a direction orthogonal to conveying direction of the paper T. 
     As shown in  FIG. 1 , the pushing member  211  and the receiving member  212  are provided to align a front end and a rear end of the paper T in the conveying direction of the paper T. The pushing member  211  is disposed on an upstream side in the conveying direction of the sheet. The receiving member  212  is disposed on a downstream side in the conveying direction of the sheet. 
     The pushing member  211  is formed to have a cross-section that is substantially L-shaped. In addition, a driving pulley  213  and a driven pulley  214  are disposed below the upstream sheet placement member  201 A. An endless belt  215  is stretched around the driving pulley  213  and the driven pulley  214 . The pushing member  211  is attached to the endless belt  215 . In addition, the pushing member  211  projects from above the upstream sheet placement member  201 A at a substantially central position in the width direction of the upstream sheet placement member  201 A. 
     The driving pulley  213  is disposed at a position corresponding to the substantially central position of the upstream sheet placement member  201 A in the sheet conveying direction. The driven pulley  214  is disposed in the vicinity of an upstream end of the upstream sheet placement member  201 A. A rotational driving force from a motor (not shown) is transferred to the driving pulley  213  by a driving mechanism (not shown). The driving pulley  213  and the driven pulley  214  can rotate back and forth. As the driving pulley  213  rotates, the driven pulley  214  is driven to rotate via the endless belt  215 . This makes the pushing member  211  project from an upper part of the upstream sheet placement member  201 A and move in a direction parallel to the sheet conveying direction. 
     The receiving member  212  is formed to have a cross-section that is substantially L-shaped. In addition, a driving pulley  216  and a driven pulley  217  are disposed below the downstream sheet placement member  201 B. An endless belt  218  is stretched around the driving pulley  216  and the driven pulley  217 . The receiving member  212  is attached to the endless belt  218 . In addition, the receiving member  212  projects from above the downstream sheet placement member  201 B at a substantially central position in the width direction of the downstream sheet placement member  201 B. 
     The driving pulley  216  is disposed in the vicinity of an upstream end of the downstream sheet placement member  201 B. The driven pulley  217  is disposed in the vicinity of a downstream end of the downstream sheet placement member  201 B. A rotational driving force from a motor (not shown) is transferred to the driving pulley  216 , by a driving mechanism (not shown). The driving pulley  216  and the driven pulley  217  can rotate back and forth. As the driving pulley  216  rotates, the driven pulley  217  is driven to rotate via the endless belt  218 . This makes the receiving member  212  project from above the downstream sheet placement member  201 B and move along an entire length of the downstream sheet placement member  201 B, in a direction parallel to the sheet conveying direction. 
     By moving the pushing member  211  and the receiving member  212  according to a size of the paper T (a length thereof in the conveying direction), the paper T introduced into the upstream sheet placement member  201 A and the downstream sheet placement member  201 B is aligned in a direction parallel to the sheet conveying direction, in other words a longitudinal direction of the paper T. 
     Widthwise alignment members (not illustrated) are members for aligning the paper T in a direction orthogonal to the conveying direction of the paper T, in other words in the width direction of the paper T. The widthwise alignment members are provided in pair in a direction parallel to the conveying direction of the paper T. The pair of widthwise alignment members is arranged above the upstream sheet placement member  201 A and the downstream sheet placement member  201 B, across the blade member  222  in the sheet conveying direction, with an interval therebetween in the width direction. The pair of widthwise alignment members performs widthwise alignment and skew compensation of the paper T. The pair of widthwise alignment members is provided above the upstream sheet placement member  201 A. The pair of widthwise alignment members has a rack and pinion mechanism (not illustrated). The rack and pinion mechanism is driven in connection with a motor (not illustrated) that can rotate back and forth. 
     The rack and pinion mechanism and the motor move the widthwise alignment member according to a size (a length in the width direction) of the paper T having been introduced onto the upstream sheet placement member  201 A and the downstream sheet placement member  201 B. Alignment such as widthwise alignment and skew compensation of the paper T is thus performed. 
     The folding portion  220  forms a fold on the paper T at the first nip N 1  (described later). The folding portion  220  dispatches the paper T on which the fold has been formed toward the second discharging unit  230 . 
     The folding portion  220  is provided with a blade member  222  (first folding member) and a pair of folding rollers  223  (second folding member). In addition, the folding portion  220  has a driving mechanism  300  and a rotational position detecting mechanism  400 . 
     The blade member  222  is a member that is brought into contact with the paper T to thereby perform the folding processing on the paper T. 
     The blade member  222  has a tip end part  222   a  that is brought into contact with the paper T. An edge part of the blade member  222  that is on an opposite side to the tip end part  222   a  is held by a holding member  222   b.    
     The blade member  222  is disposed on the opposite face  203  side, which is opposite to the sheet placement face  202 , of the sheet placement member  201 . The blade member  222  is disposed to be movable between an initial position HP (refer to  FIG. 6 ) and a protruded position TP (refer to  FIG. 8 ). At the initial position HP (refer to  FIG. 6 ), the tip end part  222   a  of the blade member  222  is positioned at a predetermined position on the opposite face  203  side. At the protruded position TP (refer to  FIG. 8 ), the tip end part  222   a  of the blade member  222  penetrates the through portion  204  and is positioned at a predetermined position on the sheet placement face  202  side. 
     The blade member  222  folds and moves the paper T by moving from the initial position HP to the protruded position TP in a state in which the paper T is placed on the sheet placement member  201 . 
     More specifically, the blade member  222  is brought into contact with the paper T so as to push out the paper T, and bends (folds) and feeds the paper T into the first nip N 1  (described later). The blade member  222  moves in a direction which is substantially orthogonal to the sheet placement face  202  including the sheet conveying direction and the sheet width direction. 
     The pair of folding rollers  223  is disposed on the sheet placement face  202  side of the sheet placement member  201 . In the present embodiment, the pair of folding rollers  223  is disposed above the blade member  222 . 
     The pair of folding rollers  223  includes a first roller  223 A and a second roller  223 B. Both of the first roller  223 A and the second roller  223 B constituting the pair of folding rollers  223  are rotationally driven via a rotational driving mechanism which is not illustrated. 
     The first nip N 1  is formed between the first roller  223 A and the second roller  223 B. 
     The pair of folding rollers  223  pinches and receives the paper T thus folded as well as the blade member  222  in a state in which the blade member  222  is positioned at the protruded position TP. 
     The driving mechanism  300  is a driving mechanism that makes the blade member  222  reciprocate between the initial position HP and the protruded position TP. 
     The driving mechanism  300  includes a rotational driving unit  360  (refer to  FIG. 4 ), a rotating member  350  (refer to  FIG. 2 ), and a cam mechanism  310  (converting unit). 
     The rotational driving unit  360  can output a rotational driving force. The rotational driving unit  360  is configured to be capable of reversing a direction of the rotational drive. The rotational driving unit  360  is configured to include, for example, a motor. 
     The rotational driving unit  360  is configured to be capable of reversing a rotational direction between a positive rotational direction, which is a normal rotational direction, and a negative rotational direction, which is a rotational direction opposite to the positive rotational direction. 
     The rotational driving unit  360  is controlled by the rotational drive control unit  370  (described later, refer to  FIG. 4A ). For example, in a case in which the rotational drive control unit  370  (drive control unit) receives a predetermined signal and determines that the blade member  222  is in a state of moving from the initial position HP to the protruded position TP, the rotational driving unit  360  is controlled by the rotational drive control unit  370  to reverse the direction of rotational drive. 
     Alternatively, in a case in which the rotational drive control unit  370  (drive control unit) receives a predetermined signal and determines that the blade member  222  is in a state of moving from the protruded position TP to the initial position HP, the rotational driving unit  360  is controlled by the rotational drive control unit  370  to maintain the direction of rotational drive. 
     Here, the predetermined signal is a signal that is output in a case in which a jam detection unit (not illustrated) detects a paper jam, a signal that is output when a monitoring unit for monitoring a load in the rotational driving unit  360  (not illustrated) detects an overload, and the like. 
     In addition, the rotational driving unit  360  is controlled by the rotational drive control unit  370  to stop the rotational drive, for example in a case in which the rotational drive control unit  370  detects that the blade member  222  is positioned at the initial position HP based on rotational position information received from the rotational position detecting mechanism  400  (described later). 
     The rotating member  350  is directly or indirectly connected to the rotational driving unit  360 . 
     The rotating member  350  includes a shaft member  351  and a rotating plate member  352  that is connected to an end of the shaft member  351 . 
     The rotating member  350  is rotated by the rotational driving force from the rotational driving unit  360 . 
     In other words, the shaft member  350  is rotated by the rotational driving force from the rotational driving unit  360 . And the rotating plate member  352  is rotated by the rotational driving force from the rotational driving unit  360 , via the shaft member  351 . 
     The cam mechanism is a driving mechanism that converts a rotational motion of the rotating member  350  into a reciprocating motion. The cam mechanism  310  converts the rotational motion into the reciprocating motion in such a way that, as the rotating member  350  makes one rotation, the blade member  222  makes one reciprocation. 
     The cam mechanism  310  includes a cam member  311 , a contacting member  312 , and a spring member  380 . The cam member  311  is connected to the shaft member  351  in the rotating member  350 . The cam member  311  rotates integrally with the rotating member  350 . 
     The contacting member  312  is formed on the holding member  222   b . The holding member  222   b  holds the blade member  222 . The contacting member  312  is disposed to be in contact with an external edge of the cam member  311 . The contacting member  312  is configured to reciprocate as the cam member rotates. Here, the holding member  222   b  on which the contacting member  312  is formed holds the blade member  222 . As a result, the blade member  222  reciprocates as the contacting member  312  reciprocates. 
     A first end  381  of the spring member  380  is connected to the shaft member  351 . A second end  383  of the spring member  380  is connected to the holding member  222   b . The spring member  380  biases the contacting member  312  toward the cam member  311 , via the shaft member  351  and the holding member  222   b.    
     The spring member  380  maintains a state in which the contacting member  312  is in contact with the external edge of the cam member  311 . 
     The rotational position detecting mechanism  400  detects a rotational position of the rotating member  350 . The rotational position detecting mechanism  400  outputs rotational position information. 
     The rotational position detecting mechanism  400  includes a detected portion  410  and a detecting sensor  420 . 
     The detected portion  410  is disposed on an external edge of the rotating plate member  352  constituting the rotating member  350 . The detected portion  410  includes a first region  401  (transparent region) and a second region  402  (non-transparent region). 
     The first region  401  is a region that is positioned at a measured position of the detecting sensor  420  which is described later, in a state in which the blade member  222  is positioned between the initial position HP and a position immediately before the protruded position TP. In the present embodiment, the first region  401  is a region that transmits light that is output from the detecting sensor  420 . 
     The second region  402  is a region that is positioned at the measured position of the detecting sensor  420  which is described later, in a state in which the blade member  222  is positioned between the protruded position TP and a position immediately before the initial position HP. In the present embodiment, the second region  402  is a region that does not transmit light that is output from the detecting sensor  420  (non-transparent region, light shielding region). 
     It should be noted that a mode of the detected portion  410  is not limited to the above mentioned mode. 
     The detecting sensor  420  is disposed at a position corresponding to the detected portion  410 . 
     The detecting sensor  420  detects detection information (position information) relating to the detected portion  410 . In addition, the detecting sensor  420  outputs the detection information (position information) thus detected. In other words, the detecting sensor  420  detects a rotational position of the rotating member  350  (rotating plate member  352 ) and outputs the rotational position information (position information). 
     Next, the functional configuration of the copy machine  1  will be described with reference to  FIGS. 4A and 4B .  FIG. 4A  is a block diagram showing a functional configuration in a copy machine (post processing device) of the first embodiment.  FIG. 4B  is a diagram explaining a table stored in a storage unit. 
     The copy machine main body  2  is provided with the above described constituent features (the original conveying unit  10 , the original scanning unit  20 , the first paper conveying unit  30 , the toner image forming unit  40 , the transfer unit  50 , and the fusing unit  60 ). An image forming unit  3  is configured from the first paper conveying unit  30 , the toner image forming unit  40 , the transfer unit  50 , and the fusing unit  60 . Description of the constituent elements that have been described above will be omitted. In addition to the abovementioned functional configuration, the copy machine main body  2  further includes an operation unit  70 , a storage unit  80 , and a main control unit  90 . 
     The operation unit  70  includes a numeric keypad (not shown), a touch panel (not shown), a start key (not shown), and the like. The numeric keypad is operated for input of numerals related to print copy number and the like. The touch panel displays a plurality of keys to which various functions are assigned. As the various functions, a function for setting the copy magnification, a function for allocating a plurality of pages to a single sheet of paper T (2 in 1, and the like), a function for executing the punching processing, the stapling processing or the fold processing can be exemplified. The keys displayed on the touch panel are operated (by touch) in order to execute any of the various functions on the copy machine  1 . The start key is operated to execute printing. In response to operation of any of the keys, the operation unit  70  supplies a signal expressing operation of the key to the control unit  90 . 
     The storage unit  80  is configured from a hard disk, semiconductor memory, and the like. The storage unit  80  stores image data based on the original G read by the original scanning unit  20 . In addition, the storage unit  80  stores a control program used in the copy machine  1 , data used by the control program, and the like. 
     The main control unit  90  controls the original conveying unit  10 , the original scanning unit  20 , the image forming unit  3 , the touch panel constituting the operation unit  70 , and a post processing control unit  150 . 
     The post processing device  100  is provided with the above described constituent elements (the second paper conveying unit  110 , the punching unit  120 , the stapling unit  130 , and the folding unit  190 ). Description of the constituent elements that have been described above will be omitted. The post processing device  100  is further provided with, in addition to the above described constituent elements, the post processing control unit  150  and a storage unit  600 . 
     The folding unit  190  includes the rotational driving unit  360 , a signal receiving unit  365 , and the rotational drive control unit  370 . The rotational driving unit  360  is as described above. 
     The signal receiving unit  365  receives a predetermined signal. After receiving a predetermined signal, the signal receiving unit  365  notifies the rotational drive control unit  370  of the reception. 
     Here, the signal is, as described above, a signal that is output in a case in which a jam detection unit (not illustrated) detects a paper jam, a signal that is output when a monitoring unit for monitoring a load in the rotational driving unit  360  (not illustrated) detects an overload, and the like. 
     The rotational drive control unit  370  controls the rotational driving unit  360 . 
     The rotational drive control unit  370  receives the rotational position information from the rotational position detecting mechanism  400  (detecting sensor  420 ). 
     In addition, the rotational drive control unit  370  receives the abovementioned notification from the signal receiving unit  365 . 
     The rotational drive control unit  370 , when the signal receiving unit  365  receives the predetermined signal (when the notification from the signal receiving unit  365  is received), determines whether the blade member  222  is in a state of moving from the initial position HP to the protruded position TP or the blade member  22  is in a state of moving from the protruded position TP to the initial position HP based on the rotational position information thus received. 
     And then, in a case in which the blade member  222  is determined to be in the state of moving from the initial position HP to the protruded position TP, the rotational drive control unit  370  controls the rotational driving unit  360  to reverse the direction of rotational drive. 
     In a case in which the blade member  222  is determined to be in the state of moving from the protruded position TP to the initial position HP, the rotational drive control unit  370  controls the rotational driving unit  360  to maintain the direction of rotational drive. 
     Furthermore, after performing the abovementioned control, in a case in which the blade member  222  is determined to be positioned at the initial position HP based on the rotational position information, the rotational drive control unit  370  controls the rotational driving unit  360  to stop the rotational drive. 
     Here, as described above, the rotational drive control unit  370  determines whether the blade member  222  is in a state of moving from the initial position HP to the protruded position TP or the blade member  22  is in a state of moving from the protruded position TP to the initial position HP based on the rotational position information thus received. 
     The rotational drive control unit  370  makes the abovementioned determination based on the rotational position information thus received, with reference to the table  610  stored in the storage unit  600  which is described later. 
     The table  610  stored in the storage unit  600  stores a (current) rotational status, a detection status, a blade status (position), and a type of driving control, in association with each other. 
     In the present embodiment, in a case in which the rotational position information including information not “detected” is received from the detecting sensor  420 , the rotational drive control unit  370  determines that the blade member  222  is in the state of moving from the initial position HP to the protruded position TP. And then, the rotational drive control unit  370  controls the rotational driving unit  360  to reverse the direction of the rotational drive. 
     In the present embodiment, in a case in which the rotational position information including information “detected” is received from the detecting sensor  420 , the rotational drive control unit  370  determines that the blade member  222  is in the state of moving from the protruded position TP to the initial position HP. And then, the rotational drive control unit  370  controls the rotational driving unit  360  to maintain the direction of the rotational drive. 
     In addition, after the above described control, if the rotational direction of the rotational driving unit  360  is the positive rotation, when the rotational drive control unit  370  detects that the information received from the detecting sensor  420  is changed from “detected” to “not detected”, the blade member  222  is detected to be positioned at the initial position HP. And then, the rotational drive control unit  370  controls the rotational driving unit  360  to stop the rotational drive. 
     Furthermore, after the above described control, if the rotational direction of the rotational driving unit  360  is the negative rotation, when the rotational drive control unit  370  detects that the information received from the detecting sensor  420  is changed from “not detected” to “detected”, the blade member  222  is detected to have slightly overpassed the initial position HP. And then, the rotational drive control unit  370  controls the rotational driving unit  360  to stop the rotational drive. 
     Here, a case in which the initial position HP is positioned not on the edge part of the first region  401 , but more inward than the edge part of the first region  401  is described. 
     After the above described control, if the rotational direction of the rotational driving unit  360  is the positive rotation, when the rotational drive control unit  370  detects that the information received from the detecting sensor  420  is changed from “detected” to “not detected”, the rotational drive control unit  370  controls the rotational driving unit  360  to stop the rotational drive after further making a predetermined amount of positive rotation. 
     After the above described control, if the rotational direction of the rotational driving unit  360  is the negative rotation, when the rotational drive control unit  370  detects that the information received from the detecting sensor  420  is changed from “not detected” to “detected”, the rotational drive control unit  370  controls the rotational driving unit  360  to stop the rotational drive in the negative rotation and to make a predetermined amount of positive rotation. 
     Next, the operation of the copy machine  1  will be described. Here, a case of performing post processing after copying of an original G placed on the original placement portion  11  will be described. 
     The control unit  90  detects the operation of the start key when a signal is supplied that indicates that the start key constituting the operation unit  70  has been operated. Then, the control unit  90  drives the first roller  12  of the original conveying unit  10  to thereby supply the original G to the first scanning surface  21   a . The control unit  90  produces image data based on the original G supplied to the first scanning surface  21   a  by the original scanning unit  20 . The main control unit  90  temporarily stores the image data thus generated by the original scanning unit  20  in the storage unit  80 . The control unit  90  forms a toner image on the paper T based on the image data temporarily stored in the storage unit  80 . The main control unit  90  controls the first paper conveying unit  30  constituting the image forming unit  3 , the toner image forming unit  40 , the transfer unit  50 , and the fusing unit  60 , respectively. In other words, the main control unit  90  drives the second roller  31  or the third roller  32  to convey the paper T to the transfer unit  50 . In addition, the control unit  90  supplies color image data produced for each color based on the image data to the respective laser scanning units  43 . The main control unit  90  forms an electrostatic latent image on the photosensitive drum  41  by means of the laser light submitted from the laser scanning units  43 . The main control unit  90  forms a toner image on the photosensitive drum  41  using the developing unit  44 . The main control unit  90  subjects the toner image thus formed on the photosensitive drum  41  to primary transfer onto the intermediate transfer belt  48 . The control unit  90  uses the secondary transfer roller  51  to perform secondary transfer of the toner image having been subjected to the primary transfer to the intermediate transfer belt  48  onto the paper T. The main control unit  90  controls the heating rotating body  61  to be heated to a predetermined temperature. The main control unit  90  melts toner in the toner image having been subjected to secondary transfer to the paper T. The main control unit  90  fuses the toner onto the paper T by the pressurizing rotating body  62  that is brought into pressure contact with the heating rotating body  61 . Furthermore, the main control unit  90  uses the first paper conveying unit  30  to discharge the paper T onto which the toner image is fused from the second paper discharging unit  38 . 
     The main control unit  90  controls the post processing control unit  150  to perform the post processing on the paper T being discharged from the second paper discharging unit  38 . 
     The post processing control unit  150  introduces the paper T having been discharged from the second paper discharging unit  38  to the post processing device  100  by means of the second paper conveying unit  110 . And then, the post processing control unit  150  stops the conveyance of the paper T by the second paper conveying unit  110  at the punching unit  120 . 
     The post processing control unit  150  lowers a punching processing unit (not illustrated) of the punching unit  120  toward the paper T. The post processing control unit  150  thus forms a punched hole on the paper T. The post processing control unit  150  conveys the paper T, on which the punched hole is formed, by means of the second paper conveying unit  110 . The post processing control unit  150  discharges the paper T having been conveyed by the second paper conveying unit  110  from the first discharging unit  113 . 
     In a case of performing the stapling processing, the post processing control unit  150  makes the branching guide  112  reverses the conveying direction of the paper T having been introduced into the post processing device  110  to a direction orthogonal to the conveying direction of the paper T. As a result, the post processing control unit  150  temporarily retains the paper T at the paper receiving tray  131 . The post processing control unit  150  moves the stapling processing unit  133  when a predetermined number of sheets of the paper T is temporarily retained at the paper receiving tray  131 . The post processing control unit  150  then makes the stapling processing unit  133  perform the stapling processing in the vicinity of the edge part or the central part of the paper T. In a case in which the stapling processing unit  133  has performed the stapling processing in the vicinity of the edge part of the paper T, the post processing control unit  150  discharges a stack of paper having been stapled from the first discharging unit  113 . On the other hand, in a case in which the stapling processing unit  133  has performed the stapling processing in the vicinity of the central part of the paper T, the post processing control unit  150  conveys a stack of paper having been saddle stitched to the folding processing unit  190  (the sheet placement member  201 ). 
     In the folding processing, the rotational drive control unit  370  controls the rotational driving unit  360  to move the blade member  222  toward the stack of paper (paper T) placed on the sheet placement member  201  (sheet placement face  202 ). The blade member  222  is thus moved toward the pair of folding rollers  223  while folding the stack of paper. The blade member  222  tucks the stack of paper thus folded into the first nip N 1 . The post processing control unit  150  then folds the stack of paper by means of the pair of folding rollers  223 . Furthermore, the post processing control unit  150  controls various driving units (not illustrated) to convey the stack of paper thus folded toward the second discharging unit  230 . 
     Next, the folding processing (operation) of the folding processing unit  190  in post processing device  100  is described with reference to  FIGS. 5 to 12 . 
       FIG. 5  is a flow chart explaining an operation in the folding processing unit in the copy machine of the first embodiment.  FIG. 6  is a diagram explaining a state in which the blade is positioned at an initial position.  FIG. 7  is a diagram explaining a state in which the blade is moving from the initial position to the protruded position.  FIG. 8  is a diagram explaining a state in which the blade is positioned at the protruded position.  FIG. 9  is a diagram explaining a state in which the blade has been moved from the protruded position to the initial position side.  FIG. 10  is a diagram explaining a state in which the blade has been brought back to the initial position.  FIG. 11  is a diagram explaining a state in which the blade has been further moved from the position of  FIG. 7  to the protruded position side.  FIG. 12  is a diagram explaining a state in which the blade has been further moved from the position of  FIG. 8  to the initial position side. 
     First, normal folding processing (operation) is described with reference to  FIGS. 6 to 10 . 
     As shown in  FIG. 6 , the paper T is introduced by the conveying path  110   d  into the folding processing unit  190 . The paper T having been introduced into the folding processing unit  190  is placed on the upstream sheet placement face  202 A of the upstream sheet placement member  201 A and the downstream sheet placement face  202 B of the downstream sheet placement member  201 B. Furthermore, the position of the paper T is aligned in the alignment portion  210 . 
     In this state, the blade member  222  stands by while being positioned at the initial position HP. More specifically, the blade member  222  stands by while being positioned below (on the opposite face  203  side of) the upstream sheet placement face  202 A of the upstream sheet placement member  201 A and the downstream sheet placement face  202 B of the downstream sheet placement member  201 B. 
     Subsequently, the rotational drive control unit  370  controls the rotational driving unit  360  to rotationally drive in the positive rotational direction. 
     As a result, as shown in  FIG. 7 , as the rotating member  350  positively rotates, the cam member  311  connected to the rotating member  350  positively rotates. 
     In addition, the tip end part  222   a  of the blade member  222  moves via the contacting member  312 , and penetrates through the through portion  204 , to the sheet placement face  202  side. The blade member  222  moves from the initial position HP toward the protruded position TP. 
     In addition, the blade member  222  is brought into contact with the paper T and moves the paper T toward the pair of folding rollers  223  while folding the paper T. 
     Subsequently, the rotational drive control unit  370  controls the rotational driving unit  360  to continue the rotational drive in the positive rotational direction. 
     As a result, as shown in  FIG. 8 , the rotating member  350  further positively rotates and the cam member  311  connected to the rotating member  350  further positively rotates. 
     In addition, as a result, the tip end part  222   a  of the blade member  222  further moves via the contacting member  312  to move to (position at) the protruded position TP. 
     In addition, as a result, the blade member  222  tucks the paper T thus folded into the first nip N 1  provided by the pair of folding rollers  223 . 
     Subsequently, the rotational drive control unit  370  controls the rotational driving unit  360  to continue the rotational drive in the positive rotational direction. 
     As a result, as shown in  FIG. 9 , the rotating member  350  further positively rotates and the cam member  311  connected to the rotating member  350  further positively rotates. 
     In addition, as a result, in association with movement of the contacting member  312  that is brought into contact with an external edge of the cam member  311  by the spring member  380 , the tip end part  222   a  of the blade member  222  moves from the protruded position TP toward the initial position HP. 
     Furthermore, as a result, the blade member  222  is spaced apart from the paper T having been folded. 
     Subsequently, the rotational drive control unit  370  controls the rotational driving unit  360  to continue the rotational drive in the positive rotational direction. 
     As a result, as shown in  FIG. 10 , the rotating member  350  further positively rotates and the cam member  311  connected to the rotating member  350  further positively rotates. 
     In addition, as a result, in association with movement of the contacting member  312  that is brought into contact with the external edge of the cam member  311  by the spring member  380 , the tip end part  222   a  of the blade member  222  further moves toward (positions at) the initial position HP. 
     Furthermore, in a case in which the blade member  222  is detected to position at the initial position HP based on the position information from the detecting sensor  420 , the rotational drive control unit  370  controls the rotational driving unit  360  to stop the rotational drive. 
     The pair of folding rollers  223  receives the paper T being tucked by the blade member  222  and feeds the paper T to the conveying path  110   e  while making a fold. 
     The paper T after the folding processing is discharged from the second discharging unit  230 . 
     And then, the post processing device  100  (the folding processing unit  190 ) stops the folding processing (operation). 
     Next, based on  FIG. 5 , the folding processing (operation) in a case of abnormality will be described with reference to  FIGS. 11 and 12 . 
     In Step ST 11 , the rotational drive control unit  370  determines whether a notification of reception of a predetermined signal from the signal receiving unit  365  is received. 
     In a case in which the notification is not received (Step ST 11 , NO), the rotational drive control unit  370  returns the processing to a state before Step ST 11 . 
     In a case in which the notification is received (Step ST 11 , YES), the rotational drive control unit  370  advances the processing to Step ST 12 . 
     Subsequently, in Step ST 12 , the rotational drive control unit  370  determines whether the blade member  222  is in the state of moving from the initial position HP to the protruded position TP based on the rotational position information received from the detecting sensor  320 . 
     In a case in which the blade member  222  is determined to be in the state of moving from the initial position HP to the protruded position TP, as shown in  FIG. 11  (Step ST 12 , YES), the rotational drive control unit  370  advances the processing to Step ST 13 . 
     In a case in which the blade member  222  is determined not to be in the state of moving from the initial position HP to the protruded position TP, for example as shown in  FIG. 12  (in a state in which the blade member  22  is determined to be in a state of moving from the protruded position TP to the initial position HP) (Step S 12 , NO), the rotational drive control unit  370  advances the processing to Step ST 14 . 
     Subsequently, in Step ST 13 , the rotational drive control unit  370  controls the rotational driving unit  360  to drive in a negative rotation in a reversed rotational direction (to reverse the rotational direction). 
     For example, the blade member  222  moves from a position shown in  FIG. 11  to the initial position HP shown in  FIG. 6  via the position shown in  FIG. 7 . 
     As a result, the blade member  222  returns to the initial position HP without being positioned at the protruded position TP, where a higher load is applied. The blade member  222  can thus return to the initial position HP in a low load state. 
     In addition, in Step ST 14 , the rotational drive control unit  370  controls the rotational driving unit  360  to maintain the positive rotation. 
     For example, the blade member  222  moves from the position shown in  FIG. 12  to the initial position HP shown in  FIG. 10  via the position shown in  FIG. 9 . 
     The blade member  222  has already overpassed the protruded position TP where a higher load is applied. As a result, in a state in which the rotational driving unit  360  is maintained in the positive rotation, the blade member  222  can thus return to the initial position HP in a low load state. 
     And then, in Step ST 15 , the rotational drive control unit  370  determines whether the blade member  222  is positioned at the initial position HP based on the rotational position information. 
     In a case in which the blade member  222  is not determined to be positioned at the initial position HP (Step ST 15 , NO), the rotational drive control unit  370  returns the processing to a state before Step ST 15 . 
     Furthermore, in a case in which the blade member  222  is determined to be positioned at the initial position HP (Step ST 15 , YES), the rotational drive control unit  370  controls the rotational driving unit  360  to stop the drive. 
     And then, the post processing device  100  (the folding processing unit  190 ) stops the folding processing (operation). 
     According to the first embodiment, a post processing device that suppresses damage of the folding member and that can reduce an operator&#39;s burden in a case of failure can be provided. 
     In addition, according to the first embodiment, an image forming apparatus including the post processing device can be provided. 
     In addition, according to the first embodiment, the post processing device  100  (copy machine  1 ) includes: the driving mechanism that makes the blade member  222  reciprocate between the initial position HP and the protruded position TP, including the rotational driving unit  360  that can output a rotational driving force and can reverse the direction of rotational drive, the rotating member  350  that is directly or indirectly connected to the rotational driving unit  360  and is rotated by the rotational driving force from the rotational driving unit  360 , and the cam mechanism  310  that is connected to the rotating member  350  and converts a rotational motion of the rotating member  350  into a reciprocating motion; the rotational position detecting mechanism  400  that detects a rotational position of the rotating member  350  and outputs rotational position information; the signal receiving unit  365  that receives a predetermined signal; and the rotational drive control unit  370  that receives the rotational position information from the rotational position detecting mechanism  400 , and when the signal receiving unit  365  receives the predetermined signal, determines whether the blade member  222  is in a state of moving from the initial position HP to the protruded position TP or the blade member  222  is in a state of moving from the protruded position TP to the initial position HP based on the rotational position information, and, in a case in which the blade member  222  is determined to be in the state of moving from the initial position HP to the protruded position TP, controls the rotational driving unit  360  to reverse the direction of rotational drive, and in a case in which the blade member  222  is determined to be in the state of moving from the protruded position TP to the initial position HP, controls the rotational driving unit  360  to maintain the direction of rotational drive. 
     As a result, the post processing device  100  (the copy machine  1 ) can return the blade member  222  to the initial position HP in a low load state. As a result, the post processing device  100  (the copy machine  1 ) can suppress (further) damage to the blade member  222 . In addition, the post processing device  100  (the copy machine  1 ) can reduce the user&#39;s burden of operation. 
     Furthermore, according to the first embodiment, the rotational position detecting mechanism  400  includes the detected portion  410  that is disposed on the rotating member  350 , and the detecting sensor  420  that is disposed at a position corresponding to the detected portion  410  and detects position information relating to the detected portion  410 . 
     As a result, the post processing device  100  (the copy machine  1 ) can determine the position of the blade member  222  based on the detected information. As a result, the post processing device  100  (the copy machine  1 ) is configured in a simple configuration to be capable of determining the position of the blade member  222 . 
     Furthermore, according to the first embodiment, the cam mechanism  310  converts the rotational motion into the reciprocating motion in such a way that, as the rotating member  350  makes one rotation, the blade member  222  makes one reciprocation. As a result, the post processing device  100  (the copy machine  1 ) can correctly determine the position of the blade member  222  as well as the state of moving of the blade member  222 , by obtaining the rotational position information of the rotating member  350 . 
     Furthermore, according to the first embodiment, in a case in which the blade member  222  is determined to be positioned at the initial position HP based on the rotational position information, the rotational drive control unit  370  controls the rotational driving unit  360  to stop the rotational drive. As a result, the post processing device  100  (the copy machine  1 ) can infallibly position the blade member  222  at the initial position HP in a case of abnormality. In addition, the post processing device  100  (the copy machine  1 ) can reduce the user&#39;s burden of operation. 
     Second Embodiment 
     Next, a second embodiment of the present invention will be described in detail with reference to  FIGS. 13 and 14 .  FIG. 13  is a block diagram showing a functional configuration in a copy machine (post processing device) of the second embodiment.  FIG. 14  is a flow chart explaining an operation in the folding processing unit in the copy machine of the second embodiment. 
     In the second embodiment, description will center on the points of difference from the first embodiment. Description in relation to the first embodiment is suitably applied and employed in relation to points that are not described in particular detail in relation to the second embodiment. 
     The second embodiment of the present invention is different from the first embodiment mainly in that a rotational load monitoring unit  366  is provided in place of the signal receiving unit  365  provided in the first embodiment. 
     In the second embodiment, the rotational driving unit  360  can output a rotational driving force as in the first embodiment. The rotational driving unit  360  is configured to be capable of reversing a direction of the rotational drive. The rotational driving unit  360  is configured to include, for example, a motor. 
     The rotational driving unit  360  is configured to be capable of reversing a rotational direction between a positive rotational direction, which is a normal rotational direction, and a negative rotational direction, which is a rotational direction opposite to the positive rotational direction. 
     Here, as a motor constituting the rotational driving unit  360 , various motors such as a stepping motor, a brushed motor, a brushless motor can be used. In addition, in the second embodiment, as a detection method of rotational load in the rotational load monitoring unit  366 , a detection method suitable for characteristics of each motor can be employed. The rotational load monitoring unit  366  will be described later. 
     In the second embodiment, the rotational driving unit  360  is controlled by the rotational drive control unit  370  (described later, refer to  FIG. 13 ) as in the first embodiment. For example, in the second embodiment, in a case in which the rotational load monitoring unit  366 , which is described later, determines that the rotational load in the rotational driving unit  360  is at least a predetermined load and the rotational drive control unit  370  (drive control unit) determines that the blade member  222  is in a state of moving from the initial position HP to the protruded position TP, the rotational driving unit  360  is controlled by the rotational drive control unit  370  to reverse the direction of rotational drive. 
     Alternatively, in a case in which the rotational load monitoring unit  366 , which is described later, determines that the rotational load in the rotational driving unit  360  is at least a predetermined load and the rotational drive control unit  370  (drive control unit) receives a predetermined signal and determines that the blade member  222  is in a state of moving from the protruded position TP to the initial position HP, the rotational driving unit  360  is controlled by the rotational drive control unit  370  to maintain the direction of rotational drive. 
     In the second embodiment, the folding unit  190  includes the rotational driving unit  360 , the rotational load monitoring unit  366 , and the rotational drive control unit  370 . The rotational driving unit  360  is the same as in the first embodiment. 
     The rotational load monitoring unit  366  detects a rotational load in the rotational driving unit  360  and determines whether the rotational load is at least a predetermined load. In addition, in a case in which the rotational load in the rotational driving unit  360  is determined to be at least the predetermined load, the rotational load monitoring unit  366  notifies the rotational drive control unit  370  of the determination. 
     Here, the rotational load monitoring unit  366  can detect the rotational load based on a predetermined parameter. 
     For example, the rotational load monitoring unit  366  detects the rotational load based on a current value, rotational speed, rotational cycle, back electromotive force and the like as parameters. 
     For example, in a case in which the rotational driving unit  360  is a brushed motor or a brushless motor, a current value can be used as a parameter. 
     And then, when the current value shows a predetermined change, for example the current value is at least a predetermined value, the rotational load monitoring unit  366  determines that the rotational load of the rotational driving unit  360  is at least the predetermined load. 
     In this case, the rotational load monitoring unit  366  can be configured to include a resistive element mounted on a substrate (not illustrated) and a current detecting unit. 
     Alternatively, in a case in which the rotational driving unit  360  is, for example, a stepping motor, a brushed motor, a brushless motor and the like, the rotational speed of the rotational driving unit (motor) can be used as a parameter. 
     And then, when the rotational speed shows a predetermined change, for example the rotational speed is no greater than a predetermined speed, the rotational load monitoring unit  366  determines that the rotational load of the rotational driving unit  360  is at least the predetermined load. 
     In this case, the rotational load monitoring unit  366  can be configured to include, for example, a plurality of through holes provided at predetermined intervals on the detected portion  410  and a rotational speed calculating unit that calculates the rotational speed based on a detection result from the detecting sensor  320 . 
     Yet alternatively, in a case in which the rotational driving unit  360  is, for example, a stepping motor, a brushed motor, a brushless motor and the like, the rotational cycle can be used as a parameter. 
     And then, when the rotational cycle shows a predetermined change, for example the rotational cycle is at least a predetermined cycle, the rotational load monitoring unit  366  determines that the rotational load of the rotational driving unit  360  is at least the predetermined load. 
     In this case, the rotational load monitoring unit  366  can be configured to include, for example, one or a plurality of through holes provided on the detected portion  410  and a rotational cycle calculating unit that calculates the rotational cycle based on a detection result from the detecting sensor  320 . In addition, in a case in which the rotational driving unit  360  is configured to include a brushless motor, the rotational load monitoring unit  366  can be configured to include a hall element mounted on the substrate and a rotational cycle calculating unit that calculate the rotational cycle based on a signal that is output from the hall element. 
     The rotational drive control unit  370  controls the rotational driving unit  360 . 
     The rotational drive control unit  370  receives the rotational position information from the rotational position detecting mechanism  400  (detecting sensor  420 ). 
     In addition, in the second embodiment, the rotational drive control unit  370  receives the abovementioned notification from the rotational load monitoring unit  366 . 
     In the second embodiment, the rotational drive control unit  370 , when the rotational load monitoring unit  366  detects the rotational load of the rotational driving unit  360  (when the notification from the rotational load monitoring unit  366  is received), determines whether the blade member  222  is in a state of moving from the initial position HP to the protruded position TP or the blade member  22  is in a state of moving from the protruded position TP to the initial position HP based on the rotational position information thus received. 
     Next, in the second embodiment, based on  FIG. 14 , the folding processing (operation) in a case of abnormality will be described with reference to  FIGS. 11 and 12 . 
     A part of the operation in the second embodiment is different from the operation in the first embodiment and the rest is the same. More specifically, the operation in Step ST 21  (control flow; refer to  FIG. 14 ) of the second embodiment is different from Step ST 11  (control flow; refer to  FIG. 5 ) of the first embodiment. 
     In the second embodiment, in Step ST 21 , the rotational drive control unit  370  determines whether a notification of the rotational load being at least the predetermined load if received from the rotational load monitoring unit  366 . 
     In a case in which the notification is not received (Step ST 21 , NO), the rotational drive control unit  370  returns the processing to a state before Step ST 21 . 
     In a case in which the notification is received (Step ST 21 , YES), the rotational drive control unit  370  advances the processing to the Step ST 22 . 
     The operations from Step ST 22  to Step ST 25  in the second embodiment are the same as Step ST 12  to Step ST 15  in the first embodiment and therefore descriptions in the first embodiment are employed and descriptions for the second embodiment are omitted. 
     In addition, according to the second embodiment, the post processing device  100  (copy machine  1 ) includes: the driving mechanism that makes the blade member  222  reciprocate between the initial position HP and the protruded position TP, including the rotational driving unit  360  that can output a rotational driving force and can reverse the direction of rotational drive, the rotating member  350  that is directly or indirectly connected to the rotational driving unit  360  and is rotated by the rotational driving force from the rotational driving unit  360 , and the cam mechanism  310  that is connected to the rotating member  350  and converts a rotational motion of the rotating member  350  into a reciprocating motion; the rotational position detecting mechanism  400  that detects a rotational position of the rotating member  350  and outputs rotational position information; the rotational load monitoring unit  366  that detects a rotational load generated in the rotational driving unit  360  and determines whether the rotational load is at least a predetermined load; and the rotational drive control unit  370  that receives the rotational position information from the rotational position detecting mechanism  400 , and when the rotational load monitoring unit  366  determines that the rotational load is at least the predetermined load, determines whether the blade member  222  is in a state of moving from the initial position HP to the protruded position TP or the blade member  222  is in a state of moving from the protruded position TP to the initial position HP based on the rotational position information, and, in a case in which the blade member  222  is determined to be in the state of moving from the initial position HP to the protruded position TP, controls the rotational driving unit  360  to reverse the direction of rotational drive, and in a case in which the blade member  222  is determined to be in the state of moving from the protruded position TP to the initial position HP, controls the rotational driving unit  360  to maintain the direction of rotational drive. 
     As a result, according to the second embodiment, the post processing device  100  (the copy machine  1 ) can return the blade member  222  to the initial position HP in a low load state as in the first embodiment. As a result, the post processing device  100  (the copy machine  1 ) can suppress (further) damage to the blade member  222 . In addition, the post processing device  100  (the copy machine  1 ) can reduce the user&#39;s burden of operation. 
     Furthermore, according to the second embodiment, the rotational position detecting mechanism  400  includes the detected portion  410  that is disposed on the rotating member  350 , and the detecting sensor  420  that is disposed at a position corresponding to the detected portion  410  and detects detection information relating to the detected portion  410 . 
     As a result, according to the second embodiment, the post processing device  100  (the copy machine  1 ) can determine the position of the blade member  222  based on the detected information as in the first embodiment. As a result, the post processing device  100  (the copy machine  1 ) is configured in a simple configuration to be capable of determining the position of the blade member  222 . 
     Although the preferred embodiments of the post processing device  100  (the copy machine  1 ) according to the present invention have been described above, the post processing device  100  (the copy machine  1 ) according to the present invention is not limited to such embodiments, and may be executed in various modes. 
     In the above embodiments, the driving mechanism is configured to include the cam mechanism as the converting unit. However, the present invention is not limited thereto. The driving mechanism can be configured to include, for example, a crank mechanism. 
     The crank mechanism  310 A is described with reference to  FIGS. 15A to 15D .  FIG. 15A  is a diagram explaining a crank mechanism that composes the folding processing unit in another embodiment.  FIG. 15B  is a diagram explaining an operation of the crank mechanism.  FIG. 15C  is a diagram explaining an operation of the crank mechanism.  FIG. 15D  is a diagram explaining an operation of the crank mechanism. 
     As shown in  FIG. 15A , the driving mechanism  300 A includes a crank mechanism  370 . 
     The crank mechanism is a driving mechanism that converts a rotational motion of a crank portion  371  into a reciprocating motion via a rod portion  372 . The crank mechanism  370  converts the rotational motion into the reciprocating motion in such a way that, as the crank portion  371  makes one rotation, the blade member  222  makes one reciprocation. 
     The crank mechanism  370  includes the crank portion  371  and the rod portion  372 . 
     The crank portion  371  is rotationally driven by the driving force from the rotational driving unit  360 . 
     A first end portion of the rod portion  372  is connected to a predetermined position on an outer peripheral side of the crank portion  371 . The rod portion  372  converts a rotational motion of the crank portion  371  into a reciprocating motion. 
     The blade member  222  is attached to a second end portion of the rod portion  372 . 
     The crank mechanism  370  makes the blade member  222  reciprocate similarly to the cam mechanism  310 . 
     More specifically, as shown in  FIGS. 15B to 15D , the crank portion  371  is rotated by the rotational drive of the rotational driving unit  360 . As the crank portion  371  rotates, the rod portion  372  reciprocates. As a result, the blade member  222  connected to the second end side of the rod portion  372  reciprocates between the initial position HP and the protruded position TP. 
     In addition, in the above described embodiments, the rotational drive control unit  370  is included in the post processing device  100 . However, the present invention is not limited thereto and the rotational drive control unit  370  can be included in the copy machine main body  2 . 
     Furthermore, in the above described embodiments, the detecting sensor is a sensor that detects transmitted light. However, the present invention is not limited thereto and the detecting sensor can be a sensor that detects reflected light or a sensor that directly measures a rotational angle. 
     Moreover, in the above described embodiments, the detected portion is a portion including a light transmitting part and a light shielding part that are continued for a predetermined range. However, the present invention is not limited thereto and the detected portion can be a portion in which light transmitting parts (light shielding parts, reflecting parts) are provided at predetermined intervals, or a portion in which the light transmitting part (light shielding part, reflecting part) which is continued but has a width narrowed (or widened) from place to place is provided. 
     In addition, in the above described embodiments, the post processing device having the folding unit has been described. However, the present disclosure discloses an invention of a folding device having the folding unit as well. 
     Furthermore, the copy machine  1  according to the above described embodiments transfers a toner image onto paper T via the intermediate transfer belt  48  (indirect transfer configuration). However there is no limitation to this configuration, and the toner image formed by the photosensitive drum may be directly transferred onto the paper T (direct transfer configuration). 
     Moreover, the copy machine  1  according to the above described embodiment is configured to print on one side of the paper T. However there is no limitation to this configuration, and double-sided printing of the paper may be executed. 
     Although the copy machine  1  according to the present embodiment is a color copy machine. However there is no limitation to this configuration, and the copy machine  1  may be a black-and-white copy machine. 
     The image forming apparatus according to the present invention is not limited to the copy machine  1  described above. In other words, the image forming apparatus according to the present invention may be a multifunction peripheral provided with a copying function, a facsimile function, a printer function, and a scanning function, or may be a facsimile or a printer. 
     Furthermore, the image formation target material onto which the toner image is fixed by the image forming apparatus according to the present invention is not limited to the paper T, and may be, for example, a film sheet such as an OHP (overhead projector) sheet and the like. 
     Moreover, the folding device according to the present invention performs the folding processing on a sheet member including a sheet-like image formation target material, a film sheet, and the like.