Patent Publication Number: US-2012028779-A1

Title: Sheet processing apparatus, image forming system and sheet processing method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority from the prior U.S. Patent Application No. 61/368,588, filed on Jul. 28, 2010, the entire contents of which are incorporated herein by reference. 
     This application is also based upon and claims the benefit of priority from Japanese Patent Application No. 2010-229446, filed on Oct. 12, 2010, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     Exemplary embodiments described herein relate to a sheet processing apparatus, an image forming system and a sheet processing method provided with processing functions, such as, sorting, stapling and reinforcing functions. 
     BACKGROUND 
     Sheet processing apparatuses are known which, when some sort of cause abnormality is sensed during reinforcing operation in a saddle unit having a reinforce roller unit, causes a reinforce roller to move to a home position and causes display means to display for urging the jam processing. However, in case that the home position is near the end portion of the sheet to be reinforced, there is a problem that this position is not sufficient for releasing the jam. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a construction view of a finisher in a first embodiment; 
         FIG. 2  is a perspective view showing a shifting mechanism in the first embodiment; 
         FIG. 3  is a perspective view showing a shift tray elevating mechanism in the first embodiment; 
         FIG. 4  is a perspective view showing an outlet section to the shift tray in the first embodiment; 
         FIG. 5  is a plan view of a staple processing tray in the first embodiment as seen from a direction perpendicular to a sheet conveying plane; 
         FIG. 6  is a perspective view showing the staple processing tray and its drive mechanism in the first embodiment; 
         FIG. 7  is a perspective view showing a discharge mechanism of a sheet stack in the first embodiment; 
         FIG. 8  is a perspective view showing an edge stapler and its moving mechanism in the first embodiment; 
         FIG. 9  is a perspective view showing an obliquely rotating mechanism in the first embodiment; 
         FIG. 10  is a view to describe an operation of a moving mechanism of a fold plate in the first embodiment, and shows a state before entering into a folding operation at the center; 
         FIG. 11  is a view to describe an operation of the moving mechanism of the fold plate in the first embodiment, and shows a state to return to an original position after folding at the center; 
         FIG. 12  is a view showing a staple processing tray and a fold processing tray in the first embodiment; 
         FIG. 13  is a front view of a reinforce roller unit in the first embodiment; 
         FIG. 14  is a side view of the reinforce roller unit in the first embodiment; 
         FIG. 15  is a block diagram showing a control of a sheet processing apparatus in the first embodiment; 
         FIG. 16  is a chart of the position movement of a reinforce roller showing an ordinary reinforcing operation in the first embodiment; 
         FIG. 17  is a chart of the position movement of the reinforce roller at the time of the jam in the first embodiment; 
         FIG. 18  is a chart of an initial operation in case that the sensor is ON in the first embodiment; 
         FIG. 19  is a chart of an initial operation in case that the sensor is OFF in the first embodiment; and 
         FIG. 20  is a chart of the position movement of the reinforce roller at the time of the jam in a second embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, there is provided a sheet processing apparatus including: a fold roller pair to fold a sheet being pushed into a nip thereof, a reinforce roller to reinforce a fold of the sheet folded by the fold roller pair; a support portion to move the reinforce roller from a home position in a direction perpendicular to a sheet conveying direction; a motor to drive the support portion; a sensor to sense a position of the support portion; and a control unit which, in case that the sensor senses a position where the support portion abnormally stops, controls the support portion to move from the abnormally stopped position to a second position which is different from a first position that is a home position. 
     Hereinafter, an embodiment of a sheet processing apparatus will be described with reference to the accompanied drawings. 
     (First Embodiment) In a first embodiment, at the time of the jam, a reinforce roller moves to a position which is more distant from an end portion of a sheet to be reinforced than an ordinary home position 
       FIG. 1  shows a construction of an image forming system composed of a finisher PD as a sheet processing apparatus of a first embodiment and an image forming apparatus PR.  FIG. 1  shows the whole of the finisher PD and a part of the image forming apparatus PR. 
     In  FIG. 1 , the finisher PD is fixed to the image forming apparatus PR, and a recording medium discharged from a sheet discharge port of the image forming apparatus PR is lead to an inlet  18  of the finisher PD. A sheet passes through a path A having finishing means for finishing the sheet, and then is sorted by path selectors  15 ,  16  into any one of a path B for leading the sheet to an upper tray  201 , a path C for leading the sheet to a shift tray  202 , a path D for leading the sheet to a processing tray F (hereinafter referred to also as a staple tray) which aligns, staples or otherwise processes the sheet or sheets. 
     The sheets led to the staple tray F through the paths A and D and then aligned and stapled in the staple tray F are sorted by a guide plate  54  and a movable guide  55  that composes deflecting means into the path C for leading the sheet to the shift tray  202  and a processing tray G (hereinafter referred to also as a fold processing tray) which folds or otherwise processes the sheets. The sheets which have been folded or otherwise processed in the fold processing tray G are further strongly folded by a reinforce roller unit  400 , and then are lead to a lower tray  203  through a path H. In addition, a path selector  17  is arranged in the path D, and is kept in the state shown in  FIG. 1  by a low load spring. After the back end of the sheet passes through the path selector  17 , at least a conveying roller  9  out of the conveying rollers  9 ,  10  and a staple outlet roller  11 , and a refeed roller  8  are rotated in the reverse direction to thereby lead the back end thereof to a prestacking portion E and to cause the sheet to stay there, and the sheet is conveyed together with the next sheet superposed thereon. Such an operation like this is repeated and thereby two or more sheets can also be conveyed in the superposed state. 
     On the path A which is mutual to the paths B, C, D, an inlet sensor  301  to sense the sheet received from the image forming apparatus PR is arranged at the upstream side, and at the down stream side thereof an input roller pair  1 , a punch unit  100 , a waste hopper  101 , a conveying roller pair  2 , the path selectors  15 ,  16  are sequentially arranged. The path selectors  15 ,  16  are maintained in the state shown in  FIG. 1  by the springs, and when their solenoids are turned ON, the path selector  15  rotates upward and the path selector  16  rotates downward to thereby sort the sheet into one of the paths B, C, D. 
     The finisher PD selectively performs punching (the punch unit  100 ), jogging and edge stapling (jogger fences  53  and an edge stapler S 1 ), jogging and center stapling (jogger fences  53  and center staplers S 2 ), sorting (the shift tray  202 ) or center folding (a fold plate  74 , a fold roller pair  81  and the reinforce roller unit  400 ) for a sheet or sheets. 
     A shift tray outlet section I which is located at the most downstream position of the finisher PD includes shift outlet rollers  6 , a return roller  13 , a sheet surface sensor  330 , the shift tray  202 , a shifting mechanism J shown in  FIG. 2  and a shift tray elevating mechanism K shown in  FIG. 3 .  FIG. 2  is an enlarged perspective view of the main portion indicating the shifting mechanism J, and  FIG. 3  is an enlarged perspective view of the main portion of the shift tray elevating mechanism K. 
     In  FIGS. 1 and 3 , the return roller  13  contacts a sheet discharged from the shift outlet rollers  6  and causes the back end of the sheet to abut against an end fence  32  shown in  FIG. 2  for thereby aligning it. The return roller  13  is caused to be rotated by the rotation force of the shift outlet rollers  6 . A limit switch  333  is arranged in the vicinity of the return roller  13 , and when the shift tray  202  is lifted and raises the return roller  13 , the limit switch  333  turns on to cause a tray motor  168  to stop rotating. This prevents the shift tray  202  from overrunning. Furthermore, as shown in  FIG. 1 , the sheet surface sensor  330  is provided as a sheet surface sensing means which senses a sheet surface position of a sheet or that of a sheet stack discharged out on the shift tray  202 . 
     As shown in  FIG. 3 , the sheet surface censor  330  has a lever  30 , a sheet surface sensor  330   a  (for stapling use) and a sheet surface sensor  330   b  (for non-stapling use). The lever  30  rotates around its shaft portion and has a contact end  30   a  which makes contact with the top of the back end of a sheet loaded on the shift tray  202  and a sectorial interrupter  30   b.    
     When the sheet surface sensor  330   a  (for stapling use) and the sheet surface sensor  330   b  (for non-stapling use) sense that sheets are stacked on the shift tray  202  to a prescribed height, the tray motor  168  is driven to lower the shift tray  202  by a prescribed amount. The sheet surface position of the sheet stack on the shift tray  202  is therefore maintained at a substantially constant height. 
       FIG. 4  is a perspective view showing a construction of the outlet section I to the shift tray  202 . 
     In  FIGS. 1 and 4 , the shift outlet roller  6  has a drive roller  6   a  and a driven roller  6   b.  The driven roller  6   b  is supported at its upstream side in the sheet discharge direction and is supported swingably in the up-and-down direction, and is rotatably supported to the free end of a guide plate  33 . The driven roller  6   b  contacts the drive roller  6   a  due to its own weight or a biasing force, and a sheet is nipped between both the rollers  6   a,    6   b  and is discharged. 
     When a stapled sheet stack is to be discharged, the guide plate  33  is lifted upward and then lowered at a prescribed timing. This timing is determined on the basis of a sensing signal of a shift outlet sensor  303 . Its stop position is determined on the basis of a sensing signal of a guide plate sensor  331 , and the guide plate  33  is driven by a guide plate motor  167 . In addition, the guide plate motor  167  is drive controlled in accordance with the ON/OFF state of a limit switch  332 . 
     A construction of the staple tray F for stapling will be described. 
       FIG. 5  is a plan view of the staple tray F as seen from the direction perpendicular to the sheet conveying plane,  FIG. 6  is a perspective view showing the staple tray F and its driving mechanism, and  FIG. 7  is a perspective view showing a sheet stack discharging mechanism. As shown in  FIG. 6 , firstly sheets which are led by the staple outlet roller  11  to the staple tray F are sequentially stacked on the staple tray F. At this instant, a knock roller  12  aligns every sheet in the longitudinal direction (a sheet conveying direction), while jogger fences  53  aligns the sheet in the lateral direction (a direction perpendicular to the sheet conveying direction—sometimes referred to as a sheet width direction). Between consecutive jobs, i.e., during an interval between the last sheet of a sheet stack and the first sheet of the next sheet stack, an edge stapler S 1  is driven by a staple signal from a control unit to thereby perform a stapling operation. The sheet stack which has been stapled is immediately conveyed to the shift outlet roller  6  by a discharge belt  52  with hooks  52   a  and is discharged to the shift tray  202  which is set at a receiving position. 
     As shown in  FIG. 7 , an HP sensor  311  senses the hook  52   a  of the discharge belt  52  brought to its home position. The HP sensor  311  is turned ON/OFF by the hook  52   a.  Two hooks  52   a  are arranged at spaced face-to-face positions on the outer circumference of the discharge belt  52 , and alternately move and convey the sheet stacks housed on the staple tray F. The discharge belt  52  can be rotated in the reverse direction such that one hook  52   a  held in a stand-by position so as to move the sheet stack and the back of the other hook  52   a  at the opposite side align the leading end of the sheet stack housed in the staple tray F in the sheet conveying direction, as needed. The hook  52   a  function as aligning means of the sheet stack in the sheet conveying direction at the same time. 
     As shown in  FIG. 5 , a discharge motor  157  causes the discharge belt  52  to move via a discharge shaft  65 . The discharge belt  52  and a drive pulley  62  therefor are positioned at the center of the discharge shaft  65  in the direction of sheet width. The discharge rollers  56  are mounted on the discharge shaft  65  in a symmetrical arrangement. The discharge rollers  56  rotate at a higher peripheral speed than the discharge belt  52 . 
     As shown in  FIG. 6 , a solenoid  170  causes the knock roller  12  to move about a fulcrum  12   a  in a pendulum fashion, so that the knock roller  12  intermittently acts on the sheets transferred to the staple tray F and causes the sheets to abut against rear fences  51 . In addition, the knock roller  12  rotates counterclockwise. The jogger fences  53  are driven by a jogger motor  158  rotatable in the forward and reverse directions via a timing belt, and move back and forth in the sheet width direction. 
     In  FIG. 8 , the edge stapler S 1  is driven by a stapler motor  159  which is rotatable in the forward and reverse directions via a timing belt, and moves in the sheet width direction in order to staple a sheet stack at a prescribed position of the sheet end portion. A stapler HP sensor  312  to sense the home position of the edge stapler S 1  is provided at one end of the movable range of the edge stapler S 1 , and the stapling position in the sheet width direction is controlled in terms of the displacement of the edge stapler S 1  from the home position. As shown in the perspective view of  FIG. 9 , the edge stapler S 1  is constructed so that a striking angle of a staple can be selectively set in parallel to or obliquely to the edge portion of the sheet, and so that only the stapling mechanism portion of the edge stapler S 1  at the home position is made rotatable by a prescribed angle obliquely so as to replace staples easily. The edge stapler S 1  is rotated obliquely by an oblique motor  160 , and when a sensor  313  senses that the stapling mechanism has reached a prescribed oblique angle or a staple replacement position, the oblique motor  160  stops. After oblique stapling is finished or the replacement of staples is finished, the stapling mechanism is rotated to the original position to prepare for next stapling. 
     As shown in  FIGS. 1 and 5 , the center staplers S 2  are arranged by two, fixed to a stay  63 , and are arranged respectively at positions where the distance between the rear fences  51  and stapling positions of the center staplers S 2  are not less than a distance corresponding to one-half of the length of the maximum sheet size that can be center stapled, as measured in the conveying direction, and are arranged symmetrically to each other with respect to the alignment center in the sheet width direction. In the case of center stapling, after a sheet stack is aligned by the jogger fences  53  in the direction perpendicular to the sheet conveying direction and is aligned in the sheet conveying direction by the rear fences  51  and the knock roller  12 , the discharge belt  52  is driven to lift the back end portion of the sheet stack with its hook  52  to a position where the center portion of the sheet stack in the sheet conveying direction coincides with the stapling positions of the center staplers S 2 . The discharge belt  52  stops at this position and causes the center staplers S 2  to staple the sheet stack. The stapled sheet stack is conveyed to the fold processing tray G side and is folded at the center. 
     In the drawings, a symbol  64   a  is a front side wall,  64   b  is a rear side wall, and a symbol  310  is a sheet sensor to sense the existence or non existence of the sheets on the staple tray F. 
       FIG. 10  and  FIG. 11  are views, each describing an operation of a moving mechanism of a fold plate  74  for center folding. 
     The fold plate  74  is supported in such a manner that each of elongate slots  74   a  formed in the fold plate  74  is movably received in one of two pins  64   c  studded on each of the front and rear side walls  64   a  and  64   b.  In addition, a pin  74   b  studded on the fold plate  74  is movably received in an elongate slot  76   b  formed in a link arm  76 , and the link arm  76  swings about a fulcrum  76   a,  causing the fold plate  74  to move in the right-and-left direction in  FIGS. 10 and 11 . That is, a pin  75   b  studded on a fold plate cam  75  is movably received in an elongate slot  76   c  formed in the link arm  76 , and the link arm  76  swings in accordance with the rotation movement of the fold plate cam  75 , and in response to this movement, the fold plate  74  reciprocates in the direction perpendicular to a lower guide plate  91  and an upper guide plate  92  in  FIG. 12 . 
     The fold plate cam  75  is rotated in the direction of an arrow shown in  FIG. 10  by a fold plate motor  166 . The stop position of the fold plate cam  75  is determined by sensing both end portions of a semicircular interrupter portion  75   a  with a fold plate HP sensor  325 . 
       FIG. 10  shows the position of the fold plate  74  in the home position where the fold plate  74  is fully retracted from the sheet stack housing range of the fold processing tray G. When the fold plate cam  75  is rotated in the direction of an arrow, the fold plate  74  is moved in the direction of the arrow and enters the sheet stack housing range of the fold processing tray G.  FIG. 11  shows a position where the fold plate  74  pushes the center of the sheet stack on the fold tray G into the nip between the fold roller pair  81 . When the fold plate cam  75  is rotated in the direction of an arrow, the fold plate  74  moves in the direction of the arrow and thereby retracts from the sheet stack housing range of the fold processing tray G. 
     In the first embodiment, with respect to center folding, to fold a sheet stack at the center is assumed, but the first embodiment is also applied to a case to fold a single sheet at the center. In such a case, because a single sheet does not have to be stapled at the center, at a time point when the sheet is discharged, the sheet is fed to the fold processing tray G side, folded by the fold plate  74  and the fold roller pair  81 , and then discharged to the lower tray  203 . 
     Next, the reinforce roller unit  400  will be described. As shown in  FIG. 1 , the reinforce roller unit  400  is provided on the path H between the fold roller pair  81  and an outlet roller pair  83 . The sheet stack which has been folded by the fold plate  74  is pushed into the nip of the fold roller pair  81  and folded, and then the fold thereof is reinforced by the reinforce roller unit  400 . 
     As shown in a plan view of  FIG. 13  and a side view of  FIG. 14 , the reinforce roller unit  400  has a reinforce roller  409 , a support mechanism of the reinforce roller  409 , and a drive mechanism of the reinforce roller  409 . The drive mechanism of the reinforce roller  409  includes a drive pulley  402 , a driven pulley  404 , an endless timing belt  403  which is passed over both the pulleys  402  and  404 , and a pulse motor  401  ( FIG. 14 ) for driving the timing belt  403  to rotate. 
     The support mechanism of the reinforce roller  409  includes a support portion  407  which is connected with and moves integrally with the timing belt  403 , a guide portion  405  which the support portion  407  slides with and regulates the moving direction, an upper guide plate  415  which extends to the opposite side of the reinforce roller of the support portion  407 , regulates the tilt of the reinforce roller  409 , and prevents the guide portion  405  from bending, a roller support portion  408 , a biasing member  411  (a coil spring in  FIG. 14 ) as biasing means for biasing the reinforce roller  409  toward the folding direction of the sheet stack (downward in  FIG. 13 ,  FIG. 14 ). The support mechanism is arranged in the direction perpendicular to the sheet conveying direction, and the drive mechanism causes the reinforce roller  409  to move inside the support mechanism in the direction in which the support mechanism is arranged. 
     The rotation driving force of the pulse motor  401  is transferred to the support portion  407  connected with the timing belt  403 , via the timing belt  403  which is passed over the drive pulley  402  and the driven pulley  404 , and the support portion  407  is guided by the guide portion  405  and moves while sliding in the thrust direction of the guide member  405 . A bend-preventing portion  406  is provided between the support portion  407  and the upper guide plate  415 , and is rotatably supported to the support portion  407 , and being roller-shaped, the bend-preventing portion  406  can move integrally with the support portion  407  in the axial direction of the guide portion  405 . The reinforce roller  409  is arranged between the support portion  407  and a lower guide plate  416 , and a friction portion  410  is fitted on the circumference of the reinforce roller  409 . The reinforce roller  409  moves back and forth. 
     The rotation axis of reinforce roller  409  is supported by the roller support portion  408 , and the roller support portion  408  is supported in such a manner as to be movable in the up-and-down direction in sliding contact with the support portion  407 . In addition, the roller support portion  408  is pressurized from the support portion  407  toward the lower guide plate  416  by the biasing member  411 . In this configuration, the reinforce roller  409  can move in the thrust direction of the guide portion  405 , integrally with the support portion  407 , and during this time, the reinforce roller  409  is constantly pressurized toward the lower guide plate  416  by the biasing member  411 , and moves in the up-and-down direction. In addition, a position sensor  412  and a position sensor  413  are provided at opposite sides in the thrust direction of the guide portion  405 , as sensing means for sensing the position of the support portion  407 . In case that a detecting plate  417  provided on the support portion  407  is positioned at positions of the position sensor  412  and the position sensor  413 , the position sensors  412 ,  413  sense the support portion  407 , respectively. A sheet stack sensor  414  senses a sheet stack conveyed to the reinforce roller unit  400 . 
     The position sensor  413  senses the home position of the reinforce roller  409 . After the sheet stack is conveyed to the prescribed position and stops, the reinforce roller  409  is moved from the position of the position sensor  413  to that of the position sensor  412  to perform the reinforcing operation. In this time, the number of pulses is counted, and in case that the reinforce roller  409  is not sensed by the position sensor  412  after counting a prescribed number of the pulses, that an abnormality (lock of the mechanism, stop due to an insufficient driving torque, step-out of the motor, sheet jam) occurs during the movement of the reinforce roller  409  is judged. Here, the term “sheet jam” means to become in a state in which the reinforce roller  409  abnormally stops during the reinforcing operation by the reinforce roller  409  and the sheet can not be conveyed. 
     When judged to be abnormal, the pulse motor  401  is reversely rotated so as to return the reinforce roller  409  in the direction of the position sensor  413 . In this time, an occurrence of a sheet jam is displayed on the display portion. 
       FIG. 15  is a block diagram showing a control of the sheet processing apparatus. A control unit  1500  has a CPU  1501  and an I/O interface  1502 . Signals from switches and so on of the control panel of the image forming apparatus PR and signals from sensors  1503  are inputted into the CPU  1500  via the I/O interface  1502 . The CPU  1501  controls to drive a solenoid  1504  and a motor  1505  on the basis of the inputted signals. 
     Signals from the inlet sensor  301 , the shift outlet sensor  303 , the sheet surface sensor  330 , the guide plate sensor  331 , the sheet sensor  310 , the HP sensor  311 , the stapler HP sensor  312 , the staple changing position sensor  313 , the fold plate HP sensor  325 , the position sensor  412 , the position sensor  413  and the sheet stack sensor  414 , for example, are inputted to the CPU  1501 . 
     In order to control the finisher PD, the abnormality sensing control, and the display control for a display  1507 , the CPU  1500  executes the program written in a memory  1506 . In addition, a CPU provided in the image forming apparatus PR executes a display control for an operation and display unit in the image forming apparatus PR, in accordance with the control output of the CPU  1501 . 
       FIG. 16  is a chart of the position movement of the reinforce roller  409  showing an ordinary reinforcing operation. The home position of the reinforce roller  409  is at a position located outward from the position of the position sensor  413  (left side in  FIG. 16 ) by an A-STEP. At the time of reinforcing, after being sensed with the position sensor  413 , the reinforce roller  409  moves to the right by a B-STEP, and then returns to the left. Then after being sensed again with the position sensor  413 , the reinforce roller  409  stops at the position located outward by the A-STEP. In the case of sensing the detecting plate  417  ( FIG. 13 ,  FIG. 14 ), the position sensor  413  is turned ON, and in the case of not sensing the detecting plate  417 , the position sensor  413  is turned OFF. 
     Hereinafter, a series of flow will be described from the time of the occurrence of abnormality. Even if the pulse motor  401  is driven to cause the reinforce roller  409  to move in the direction of the position sensor  413 , the position sensor  413  is not turned ON in a prescribed time, this state means that a sheet jam is generated and an abnormality occurs. In this time, a display showing that a sheet jam is generated is made on the operating portion of the image forming apparatus PR. In addition, the finisher PD may have the display  1507  to display a sheet jam being generated. 
     In order to shorten the reinforcing time, the moving amount of the reinforce roller  409  might be preferably short. For this reason, there may be a case in which the reinforce roller  409  does not move to the sufficiently distant position at the time of releasing the jam. When the reinforce roller  409  returns at the time of the jam, because the position of the reinforce roller  409  and the state of the sheet and so on are not found, the reinforce roller  409  is caused to return to the retract position at a low speed with a large torque. 
       FIG. 17  is a chart of the position movement of the reinforce roller  409  at the time of a jam in the first embodiment. At the time of the jam, after the position sensor  413  senses the detecting plate  417  provided on the support portion  407 , the position is confirmed, and the reinforce roller  409  is caused to stop at a C-STEP having the number of steps larger than the ordinary home position. As both the positions of the home position and the retract position are positions sensed with the position sensor  413 , the positions with high certainty can be taken. 
     At the time of the normal operation, the reinforcing operation time is given priority, and the reinforce roller  409  is returned to the ordinary home position. On the other hands, as the time of the jam is an abnormal time, releasing the jam is given priority, and the reinforce roller  409  is controlled to be moved to the retract position which is distant sufficiently outward from the home position. After the jam is released, the reinforce roller  409  moves to the ordinary home position by an initial operation. Here, the initial operation means that at the time of the jam, because what position the reinforce roller  409  stops at is not found, the reinforce roller  409  once returns to the home position via the position sensor  413 . 
       FIG. 18  is a chart of an initial operation in case that the position sensor  413  is ON. In case that the position sensor  413  senses the detecting plate  417  and thereby is ON, the position sensor  413  is once turned OFF, and then after the position sensor  413  is turned ON, the reinforce roller  309  is operated to return to the home position. To begin with, when the position sensor  413  is ON, the reinforce roller  409  is moved to the right, and if the position sensor  413  is turned OFF the reinforce roller  409  is moved to the right by the A-STEP. Then the reinforce roller  409  is moved to the left, and if the position sensor  413  is turned ON, the reinforce roller  409  is moved to the left by the C-STEP and thereby returns to the home position. 
       FIG. 19  is a chart of an initial operation in case that the position sensor  413  is OFF. When the position sensor  413  does not sense the detecting plate  417  and is OFF, the reinforce roller  409  is moved to the left, and if the position sensor  413  is turned ON, the reinforce roller  409  is moved to the left by the C-STEP and thereby returns to the home position. 
     With the above-described configuration, at the time of the jam, the reinforce roller  409  can be moved to a proper position in accordance with the condition. That is, in case that the home position is near the end portion of the sheet where the sheet is to be reinforced and the jam can not be sufficiently released at the position, the reinforce roller  409  can be moved to a position suitable for releasing the jam. In case that the home position is approximated to the end portion of the sheet where the sheet is to be reinforced so as to give priority to the processing time, at the time of the jam, being realistic about the time the reinforce roller  409  can be moved to a position with margin that is the retract position. In addition, in case that the reinforce roller  409  can be driven at a low speed with a large torque from the beginning also at the time of reinforcing, and the reinforce roller  409  can be stopped in the small slowed down number of steps at the time of returning, and in addition when the home position is approximated to the end portion of the sheet where the sheet is to be reinforced as much as possible, such a control is particularly effective. 
     (Second embodiment) In a second embodiment, at the time of the jam, the reinforce roller moves to a position which is more distant than the return position. The same symbols are given to the same constituent components as in the first embodiment. 
       FIG. 20  is a chart of the position movement of the reinforce roller  409  at the time of a jam in a second embodiment. At the time of the jam, the reinforce roller  409  is moved to the right, and after the position sensor  412  senses the detecting plate  417  provided on the support portion  407 , the position is confirmed, and the reinforce roller  409  is caused to stop at the C-STEP having the number of steps larger than the return position. 
     With the above-described configuration, at the time of the jam, the reinforce roller  409  can be moved to a proper position in accordance with the condition. That is, in case that the home position is near the end portion of the sheet where the sheet is to be reinforced and the jam can not be sufficiently released at the position, the reinforce roller  409  can be moved to a position suitable for releasing the jam. In case that the home position is approximated to the end portion of the sheet where the sheet is to be reinforced so as to give priority to the processing time, at the time of the jam, being realistic about the time the reinforce roller  409  can be moved to a position with margin that is the retract position. In addition, in case that the reinforce roller  409  can be driven at a low speed with a large torque from the beginning also at the time of reinforcing, and the reinforce roller  409  can be stopped in the small slowed down number of steps at the time of returning, and in addition when the home position is approximated to the end portion of the sheet where the sheet is to be reinforced as much as possible, such a control is particularly effective. In addition, in case that at the time of the jam the reinforce roller  409  is nearer to the return position than the home position, the jam processing time can be shortened. 
     In addition, the above-described embodiments are not limited to the individual embodiment, but the first embodiment and the second embodiment can be combined. 
     While certain embodiments have been described, those embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.