Patent Publication Number: US-10310435-B2

Title: Sheet post-processing apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2016-093013, filed on May 6, 2016, the entire contents of which are incorporated herein by reference. 
     FIELD 
     An embodiment described here generally relates to a sheet post-processing apparatus, which performs post-processing on sheets on which images are formed. 
     BACKGROUND 
     In the related art, there is known a post-processing apparatus, which executes post-processing such as stapling processing on sheets stacked onto a processing tray. The sheet post-processing apparatus includes a lateral alignment member that aligns sheets misaligned in the width direction (lateral alignment processing) and a longitudinal alignment member that aligns the sheets misaligned in the direction that is orthogonal to the sheet width direction of the sheets (longitudinal alignment processing) in order to align misaligned sheets stacked onto the processing tray before the post-processing is performed. In particular, the sheet post-processing apparatus in the related art uses the longitudinal alignment member that rotates about a rotating shaft extending to the sheet width direction in order to clear the misalignment of sheets in the direction that is orthogonal to the width direction of the sheets. 
     However, in the sheet post-processing apparatus in the related art, there is a problem that once any external force is applied to the sheets after longitudinal alignment processing or lateral alignment processing are executed, the aligned sheets are misaligned. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view showing a configuration of an image-forming system according to a first embodiment. 
         FIG. 2  is a block diagram showing an electric configuration of an image-forming apparatus and a sheet post-processing apparatus according to the first embodiment. 
         FIG. 3  is a cross-sectional view schematically showing a configuration of a sheet post-processing apparatus according to the first embodiment. 
         FIG. 4  is a perspective view showing a relationship between standby trays and paddle members of the sheet post-processing apparatus according to the first embodiment. 
         FIG. 5  is a view showing a detailed structure of the paddle member of the sheet post-processing apparatus according to the first embodiment. 
         FIG. 6  is a cross-sectional view showing a standby position of a first paddle and a second paddle of the sheet post-processing apparatus according to the first embodiment. 
         FIG. 7  is a cross-sectional view showing movement of a sheet from the standby tray to a processing tray by using the first paddle of the sheet post-processing apparatus according to the first embodiment. 
         FIG. 8  is a cross-sectional view showing the longitudinal alignment processing performed by using the first paddle of the sheet post-processing apparatus according to the first embodiment. 
         FIG. 9  is a cross-sectional view showing a stop position of the first paddle and the second paddle of the sheet post-processing apparatus according to the first embodiment. 
         FIG. 10  is a cross-sectional view showing the longitudinal alignment processing performed by using the second paddle of the sheet post-processing apparatus according to the first embodiment. 
         FIG. 11  is a view showing the longitudinal alignment processing performed by using the first paddle for the second time of the sheet post-processing apparatus according to the first embodiment. 
         FIG. 12  is a view showing a sheet pressing state performed by the second paddle of the sheet post-processing apparatus according to the first embodiment. 
         FIG. 13  is a view showing that subsequent sheets are to be received where the second paddle of the sheet post-processing apparatus according to the first embodiment is in contact with the plurality of sheets. 
         FIG. 14  is a view showing the standby position of the first paddle and the second paddle of the sheet post-processing apparatus according to the first embodiment. 
         FIG. 15  is a flowchart showing a control executed by a post-processing controller of the sheet post-processing apparatus according to the first embodiment. 
         FIG. 16  is a view showing each operation position on the processing tray of a first alignment plate and a second alignment plate of a sheet post-processing apparatus according to a second embodiment. 
         FIG. 17  is a flowchart showing a control executed by a post-processing controller of the sheet post-processing apparatus according to the second embodiment. 
         FIG. 18  is a flowchart showing a control executed by a post-processing controller of a sheet post-processing apparatus according to a third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     According to one embodiment, a sheet post-processing apparatus includes a transport roller, a processing tray, a stopper, a paddle member, and a controller. The transport roller transports sheets. The processing tray holds the sheets transported by the transport roller. The stopper is disposed on an upstream side of the processing tray in a sheet transport direction. The paddle member rotates around a rotating shaft, and comes in contact with the sheets held on the processing tray. The rotating shaft is disposed in a sheet width direction of the sheets held on the processing tray, the sheet width direction is orthogonal to the sheet transport direction. The rotating paddle member comes in contact with the sheets held on the processing tray against the stopper and aligns ends of the sheets misaligned in the sheet transport direction. The controller stops rotation of the paddle member in a state that the paddle member comes in contact with the sheets held on the processing tray. Further, the controller drives the transport roller to transport subsequent sheets to the processing tray. 
     Hereinafter, a sheet post-processing apparatus of each embodiment will be described with reference to the drawings. It should be noted that in the following description, configurations having identical or similar functions are denoted by identical reference symbols, and description common thereto will sometimes be omitted. 
     With reference to  FIG. 1  to  FIG. 15 , a sheet post-processing apparatus of a first embodiment will be described.  FIG. 1  is a view showing an overall configuration of the image-forming system.  FIG. 2  is a block diagram showing an electric configuration of an image-forming apparatus  1  and a sheet post-processing apparatus  2 . The image-forming system includes the image-forming apparatus  1  and the sheet post-processing apparatus  2 . The image-forming apparatus  1  forms images on sheet-like media such as paper (hereinafter, described as “sheets”). The sheet post-processing apparatus  2  performs post-processing on the sheets transported from the image-forming apparatus. 
     The image-forming apparatus  1  shown in  FIG. 1  includes a control panel  11 , a scanner  12 , a printer  13 , a paper feed device  14 , a paper discharge device  15 , and an image-forming controller  16 . 
     The control panel  11  includes various keys that receive user&#39;s operations. For example, the control panel  11  receives an input on a type of post-processing performed on sheets. The control panel  11  transmits information on the input type of post-processing to the post-processing apparatus  2 . 
     The scanner  12  includes a read unit that reads image information of an object to be scanned. The scanner  12  transmits the read image information to the printer  13 . 
     The printer  13  forms an output image (hereinafter, described as “toner image”) on, for example, a photoreceptor by using a developer such as toner on the basis of the image information transmitted from the scanner  12  or an external device such as a client PC. The printer  13  transfers the toner image from a photoconductor to a sheet. The printer  13  applies heat and pressure to the toner image transferred onto the sheet, to fix the toner image onto the sheet. 
     The paper feed device  14  supplies a sheet to the printer  13  every time the printer  13  forms a toner image onto the photoconductor. The paper discharge device  15  transports the sheets, which are discharged from the printer  13 , to the post-processing apparatus  2 . 
     As shown in  FIG. 2 , the image-forming controller  16  controls an overall operation of the image-forming apparatus  1 . In other words, the image-forming controller  16  controls the control panel  11 , the scanner  12 , the printer  13 , the paper feed device  14 , and the paper discharge device  15 . The image-forming controller  16  is formed of a control circuit including a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory) (not shown). 
     Next, the sheet post-processing apparatus  2  will be described with reference to  FIG. 1  and  FIG. 2 . As shown in  FIG. 1 , the post-processing apparatus  2  is connected to the image-forming apparatus  1 , and is disposed adjacently to the image-forming apparatus  1 . The post-processing apparatus  2  executes the post-processing on sheets transported from the image-forming apparatus  1 , the post-processing being specified via the control panel  11  or by an external device such as a client PC. For example, the post-processing includes stapling processing or sorting processing, for example. 
     The post-processing apparatus  2  includes a standby device  21 , a processing device  22 , a discharge device  23 , and a post-processing controller  24 . The standby device  21  temporarily retains (buffers) sheets S (see  FIG. 3 ) transported from the image-forming apparatus  2 . For example, the standby device  21  keeps a plurality of subsequent sheets S to be standby during post-processing performed on preceding sheets S by the processing device  22 . The standby device  21  is provided above the processing device  22 . When the sheets in the processing device  22  are discharged to the discharge device  23 , then the standby device  21  drops the retained sheets S down to the processing device  22 . 
     The processing device  22  performs post-processing on the sheets S. For example, the processing device  22  aligns the plurality of sheets S. The processing device  22  performs stapling processing on the plurality of aligned sheets S. As a result, the plurality of sheets S are bound together. The processing device  22  discharges the sheets S, which are subjected to the post-processing, to the discharge device  23 . 
     The discharge device  23  includes a fixed tray  23   a  and a movable tray  23   b . The fixed tray  23   a  is provided to an upper portion of the post-processing apparatus  2 . The movable tray  23   b  is provided to a side portion of the post-processing apparatus  2 . The sheets S that are subjected to the stapling processing or the sorting processing and then discharged are discharged to the movable tray  23   b.    
     As shown in  FIG. 2 , the post-processing controller  24  controls an overall operation of the post-processing apparatus  2 . In other words, the post-processing controller  24  controls the standby device  21 , the processing device  22 , and the discharge device  23 . Further, as shown in  FIG. 2 , the post-processing controller  24  controls inlet rollers  32   a,    32   b , transport rollers  33   a ,  33   b , paddle members  25 , a paddle motor  28 , a first lateral alignment motor  29   a , a second lateral alignment motor  29   b , a first alignment plate  51   a , and a second alignment plate  51   b . The post-processing controller  24  is a control circuit including a CPU  241 , a ROM  242 , and a RAM  243 . Although in this embodiment, two motors of the first lateral alignment motor  29   a  and the second lateral alignment motor  29   b  are used, the respective alignment plates  51   a ,  51   b  may be moved by one motor. 
       FIG. 3  is a view schematically showing a configuration of a sheet post-processing apparatus  2  in detail. It should be noted that in description on the following embodiments, a “sheet transport direction” means a transport direction D of the sheets S to a standby tray  211  of the standby device  21  (entry direction of the sheets S to the standby tray  211 ) or a transport direction of the sheets S from a processing tray  221  to the movable tray  23   b.    
     Further, in the description on the following embodiments, an “upstream side” and a “downstream side” mean an upstream side and a downstream side in the sheet transport direction D, respectively. Further, in the description on the following embodiments, a “front end” and a “rear end” mean an “end of the downstream side” and an “end of the upstream side” in the sheet transport direction D, respectively. Additionally, in the embodiments, a direction orthogonal to the sheet transport direction D is referred to as a sheet width direction W. 
     Hereinbelow, the post-processing apparatus  2  will be described with reference to  FIG. 3 . A transport path  31  is a transport path from a sheet supply port  31   p  and a sheet discharge port  31   d . The sheet supply port  31   p  is disposed near to the image-forming apparatus  1 . The sheets S are supplied from the image-forming apparatus  1  to the sheet supply port  31   p . Meanwhile, the sheet discharge port  31   d  is located near the standby device  21 . The sheets S discharged from the image-forming apparatus  1  are discharged via the sheet discharge port  31   d  to the standby device  21 . 
     The inlet rollers  32   a  and  32   b  are provided near the sheet supply port  31   p . The inlet rollers  32   a  and  32   b  transport the sheets S, which have been supplied to the sheet supply port  31   p , toward the downstream side of the transport path  31 . For example, the inlet rollers  32   a  and  32   b  transport the sheets S, which have been supplied to the sheet supply port  31   p , to the transport rollers  33   a  and  33   b.    
     The transport rollers  33   a  and  33   b  are disposed near the sheet discharge port  31   d . The transport rollers  33   a  and  33   b  receive the sheets S transported from the inlet rollers  32   a  and  32   b . The transport rollers  33   a  and  33   b  transport the sheets S from the sheet discharge port  31   d  to the standby device  21 . 
     The standby device  21  includes a standby tray (buffer tray)  211 , a transport guide  212 , discharge rollers  213   a  and  213   b , and an opening and closing drive device (not shown). 
     The rear end of the standby tray  211  is located near the transport rollers  33   a  and  33   b . The rear end of the standby tray  211  is located to be slightly lower than the sheet discharge port  31   d  of the transport path  31 . The standby tray  211  is tilted with respect to a horizontal direction so as to gradually increase in height toward the downstream side of the sheet transport direction D. During post-processing performed in the processing device  22 , the standby tray  211  keeps a plurality of sheets S to be standby in a stacked manner. 
       FIG. 4  is a view schematically showing a relationship between the standby tray  211  and the paddle members  25  described below. The standby tray  211  includes a first tray member  211   a  and a second tray member  211   b . The first tray member  211   a  and the second tray member  211   b  are separated from each other in the sheet width direction W. The first tray member  211   a  and the second tray member  211   b  are driven by the opening and closing drive device, and move in approaching directions and separating directions. 
     The first tray member  211   a  and the second tray member  211   b , which come close to each other, hold the sheets S transported from the transport rollers  33   a  and  33   b.  Meanwhile, the first tray member  211   a  and the second tray member  211   b  move in the separating directions in the sheet width direction W so as to move the sheets S from the standby tray  211  toward the processing tray  221 . As a result, the sheets S held by the standby tray  211  drop from a space between the first tray member  211   a  and the second tray member  211   b  down to the processing tray  221 . 
     An assist arm  41  shown in  FIG. 3  is provided above the standby tray  211 . For example, the assist arm  41  has a length substantially equal to or larger than the half length of the standby tray  211  in the sheet transport direction D. In this embodiment, the assist arm  41  has a length substantially the same as the standby tray  211  in the sheet transport direction D. The assist arm  41  is a plate-like member provided above the standby tray  211 . The sheets S discharged from the transport rollers  33   a  and  33   b  enter a space between the assist arm  41  and the standby tray  211 . 
     The processing device  22  shown in  FIG. 3  includes the processing tray  221 , a stapler  222 , support rollers  223   a  and  223   b , a transport belt  224 , a stopper  225 , and a lateral alignment member  51 . 
     The processing tray  221  is provided below the standby tray  211 . The processing tray  221  is tilted with respect to a horizontal direction so as to gradually increase in height toward the downstream side of the sheet transport direction D. The processing tray  221  is tilted substantially parallel to the standby tray  211 . The ends of the plurality of misaligned sheets S moved to the processing tray  221  are aligned in the sheet width direction W by the lateral alignment member  51 . Hereinafter, aligning the ends of the misaligned sheets in the sheet width direction W may simply refer to lateral alignment processing. 
     The stapler  222  is provided to the rear end of the processing tray  221 . The stapler  222  performs stapling (binding) processing on a bundle of the plurality of sheets S on the processing tray  221 . 
     The support rollers  223   a  and  223   b  are disposed with a predetermined distance therebetween in the sheet transport direction D. The transport belt  224  is stretched over the transport rollers  223   a  and  223   b . The transport belt  224  rotates in synchronization with the rotating transport rollers  223   a  and  223   b . The transport belt  224  transports the sheets S between the stapler  222  and the discharge device  23 . 
     The stopper  225  is disposed upstream of the sheet transport direction viewed from the transport rollers  223   b.  The sheets S move from the standby tray  211  to the processing tray  221 , and come in contact with stopper  225 . Therefore the stopper  225  aligns the sheets S misaligned in the sheet transport direction. In other words, the sheets S come in contact with the stopper  225  as a reference when the ends of the sheets S misaligned in the sheet transport direction are to be aligned. Specifically, the sheets S are moved by the first paddle  25   a  and the second paddle  25   b  described below toward upstream in the sheet transport direction, and come in contact with the stopper  225 . Thus, the ends of the sheets misaligned in the sheet transport direction are aligned. Hereinafter, aligning the ends of the sheets misaligned in the sheet transport direction (aligning the ends of the sheets in the direction orthogonal to the sheet width direction W) will be simply referred to as longitudinal alignment processing. 
     The lateral alignment member  51  includes the first alignment plate  51   a  and the second alignment plate  51   b  (for example, see  FIG. 16 ). The first alignment plate  51   a  is an alignment plate located at a front side (near side) of the sheet post-processing apparatus  2 , and the second alignment plate  51   b  is an alignment plate located at a rear side (far side) of the post-processing apparatus  2 . The first alignment plate  51   a  and the second alignment plate  51   b  are movable to the W direction orthogonal to the sheet transport direction. The first alignment plate  51   a  and the second alignment plate  51   b  are movable in synchronization or independently by the first lateral alignment motor  29   a  and the second lateral alignment motor  29   b  in the sheet width direction W. As a result, the position of the sheets S is changed. The first alignment plate  51   a  and the second alignment plate  51   b  are also used to sort the sheets S. The first alignment plate  51   a  and the second alignment plate  51   b  are disposed having a predetermined space (distance) at the standby position. The sheets S moved from the standby tray  211  are stacked in the space between the first alignment plate  51   a  and the second alignment plate  51   b . The first alignment plate  51   a  and the second alignment plate  51   b  facing each other come in contact with the sheets S, and thereby the sheets S are aligned in the direction orthogonal to the sheet transport direction. It should be noted that a damper is formed on the first alignment plate  51   a.    
     The paddle member  25  shown in  FIG. 3  includes a first paddle  25   a , a second paddle  25   b , a rotating shaft  26 , and a rotating body  27 . 
     The rotating shaft  26  is the center of rotation of the first paddle  25   a  and the second paddle  25   b  as described later. The rotating shaft  26  is positioned lower than the standby tray  211 . The rotating shaft  26  extends in the sheet width direction W. The rotating shaft  26  is driven by the paddle motor  28 , and rotates in the arrow-A direction (counterclockwise direction) in  FIG. 3 . Further, a plurality of paddle members  25  are disposed in the sheet width direction W (see  FIG. 4 ). 
     Specifically, as shown in  FIG. 4 , the plurality of paddle members  25  are disposed at the rotating shaft  26  extending in the sheet width direction W. The paddle members  25  are disposed on the rotating shaft  26  symmetrically about the center of the processing tray  221  having a predetermined distance between the paddle members  25 . Further, the first paddle  25   a  and the second paddle  25   b  rotate, and come in contact with the sheets S on the processing tray  221 . The paddle members  25  are attached to the rotating shaft  26 , and thus rotate in synchronization with the rotation of the rotating shaft  26 . 
       FIG. 5  is a view showing a detailed structure of the paddle member  25 . As described above, the paddle member  25  includes the first paddle  25   a , the second paddle  25   b , and the rotating body  27 . 
     The rotating body  27  has a cylindrical shape, a part of which is absent. The rotating body  27  has a protrusion  271 . The protrusion  271  is engaged with a preformed groove of the rotating shaft  26  such that the rotating body  27  is detachably mounted to the rotating shaft  26 . Once the rotating shaft  26  rotates in the arrow-A direction (counterclockwise) in  FIG. 3 , the rotating body  27  rotates in the same direction. Further, the first paddle  25   a  and the second paddle  25   b  are attached to the rotating body  27 , and thus rotate counterclockwise together with the rotating body  27 , when the rotating shaft  26  rotates in the arrow-A direction in  FIG. 3 . 
     The first paddle  25   a  and the second paddle  25   b  are formed of an elastic material such as rubber and resin. The first paddle  25   a  protrudes from the rotating body  27  in a radial direction of the rotating body  27 , and is attached to the rotating body  27 . The first paddle  25   a  has a length L 1  in the radial direction of the rotating body  27 . The first paddle  25   a  has a shape that the thickness d 1  of the portion attached on the rotating body  27  is different from the thickness d 2  of the portion at the end of the paddle. In detail, the portion of the first paddle  25   a  between the position x 0  and the position x 1  has the thickness d 1 , the first paddle  25   a  being attached on the rotating body  27  at the position x 0 , the first paddle  25   a  protruding from the position x 0  to the position x 1  in the radial direction. Further, the thickness of the portion of the first paddle  25   a  between the position x 1  and the position x 2  gradually decreases from the position x 1  to the position x 2 , the position x 1  having the thickness d 1 . The first paddle  25   a  has the thickness d 2  (&lt;d 1 ) in the portion between the position x 2  and the position x 3 . 
     The second paddle  25   b  is attached to the rotating body  27 , the second paddle  25   b  and the first paddle  25   a  forming a predetermined angle therebetween. In other words, the second paddle  25   b  is formed on the rotating body  27  behind the first paddle  25   a  by a predetermined distance in the arrow-A direction in  FIG. 3 . 
     The second paddle  25   b  is attached to the rotating body  27 , and protrudes from the rotating body  27  in the radial direction of the rotating body  27 . The length L 2  of the second paddle  25   b  in the radial direction of the rotating body  27  is smaller than the length L 1  of the first paddle  25   a  in the radial direction of the rotating body  27 . Similar to the first paddle  25   a , the second paddle  25   b  has a shape that the thickness d 1  of the portion attached on the rotating body  27  is larger than the thickness d 2  at the end of the paddle. The shape of the second paddle  25   b  is similar to that of the first paddle  25   a , and description thereof is therefore omitted. 
     With reference to  FIG. 6  to  FIG. 14 , operations of the first paddle  25   a  and the second paddle  25   b  will be described. 
       FIG. 6  is a view showing a standby position before the first paddle and the second paddle  25   b  are rotated. The standby position is a position where the first paddle  25   a  and the second paddle  25   b  stand by when the sheets S transported from the transport rollers  33   a  and  33   b  are retained on the standby tray  211 , or when the sheets S are transported from the transport rollers  33   a  and  33   b  directly to the processing tray  221 . In other words, the standby position is a position where the longitudinal alignment processing is not performed on the sheets S by using the first paddle  25   a  and the second paddle  25   b.    
     In the standby position in  FIG. 6 , the first paddle  25   a  is located at a position where the first paddle  25   a  is not protruded from an outer circumferential surface of the transport roller  33   b  to the downstream side in the sheet transport direction D viewed from the axis of the transport roller  33   b . From a different point of view, the first paddle  25   a  is located at the upstream side, in the transport direction, of the outer circumferential surface of the transport roller  33   b  located near the standby tray  211  viewed from the standby tray  211 , where the transport of the sheets S transported from the transport roller  33   b  to the standby tray  211  is not hindered. Further, the end of the second paddle  25   b  is located at a position where the end of the second paddle  25   b  is apart from the sheets S on the processing tray  221  by a predetermined distance. 
       FIG. 7  is a view showing a state where the first paddle  25   a  is in contact with the sheets S transported from the standby tray  211  to the processing tray  221 . In the case where the predetermined number of the sheets S is retained on the standby tray  211 , the post-processing controller  24  drives the pair of standby tray members  211   a  and  211   b  (see  FIG. 4 ) to separate from each other in both the sheet width directions W, and moves the retained sheets S to the processing tray  221 . 
     The post-processing controller  24  drives the paddle motor  28  to thereby rotate the rotating shaft  26 . The first paddle  25   a  rotates together with the rotation of the rotating shaft  26 , thereby comes in contact with the sheets S dropped from the standby tray  211 , and applies a force on the sheets S to move toward the processing tray  221 . The operation that the first paddle  25   a  comes in contact with the sheets S to allow the sheets S to move from the standby tray  211  to the processing tray  221  will sometimes be referred to as “a first operation”. 
       FIG. 8  is a view showing that the first paddle  25   a  further rotates in the arrow-A direction (counterclockwise), and the longitudinal alignment processing is executed on the sheets S moved to the processing tray  221 . 
     The first paddle  25   a  in the state in  FIG. 7  further rotates in the arrow-A direction, guides the sheets S to the processing tray  221 , holds the sheets S with the processing tray  221  therebetween, and is bent (see  FIG. 8 ). The first paddle  25   a , which is still bent, rotates in the arrow-A direction, and thereby moves the sheets S toward the stopper  225  located upstream of the processing tray  221  in the sheet transport direction. Specifically, the first paddle  25   a  holds the bundle of the plurality of sheets S with the processing tray  221  therebetween, and presses the bundle against the stopper  225  such that the longitudinal alignment processing is performed. The operation that the first paddle  25   a  performs the longitudinal alignment processing on the sheets S may be called to as “a second operation”. 
       FIG. 9  is a view showing the state of the first paddle  25   a  and the second paddle  25   b  after the longitudinal alignment processing is performed on the sheets S by using the first paddle  25   a  shown in  FIG. 8 . 
     After the longitudinal alignment processing is performed on the sheets S by using the first paddle  25   a , and the first paddle  25   a  leaves from the sheets S on the processing tray  221 , the post-processing controller  24  controls the paddle motor  28  to stop rotation of the rotating shaft  26 . Thus, the rotation of the first paddle  25   a  and the second paddle  25   b  stops. The second paddle  25   b  stops at the position apart from the sheets S on the processing tray  221  by a predetermined distance. Specifically, after the longitudinal alignment processing is performed on the sheets S by using the first paddle  25   a , the first paddle  25   a  and the second paddle  25   b  stop a rotation operation at the position apart from the sheets S on the processing tray  221  for a predetermined distance. The position of the paddle member  25  shown in  FIG. 9  is referred to as “a first stop position”. 
     Here, a reason why the first paddle  25   a  and the second paddle  25   b  stop at the first stop position is as follows. After the longitudinal alignment processing is executed on the sheets S by using the first paddle  25   a , processing to align the ends of the sheets S in the sheet width direction W by the lateral alignment member  51  (lateral alignment processing) is executed. If the first paddle  25   a  or the second paddle  25   b  is in contact with the sheets S during the lateral alignment processing, the lateral alignment processing is hindered. Therefore, the first paddle  25   a  and the second paddle  25   b  are apart from the sheets S. 
       FIG. 10  is a view showing that the second paddle  25   b  performs the longitudinal alignment processing on the sheets S. The post-processing controller  24  drives the paddle motor  28  to thereby rotate again the first paddle  25   a  and the second paddle  25   b  in the arrow-A direction. The first paddle  25   a  and the second paddle  25   b  are driven by the paddle motor  28  and rotate counterclockwise. 
     Hereinafter, the sheet post-processing apparatus  2  will be described where the second paddle  25   b  is focused on. 
     The second paddle  25   b  comes in contact with the sheets S, is bent, moves the sheets S toward the stopper  225 , and presses the sheets S against the stopper  225 . The operation that the second paddle  25   b  performs the longitudinal alignment processing on the sheets S may be referred to as “a third operation”. 
     Here, a reason why the longitudinal alignment processing is further performed by using the second paddle  25   b  is as follows. When the sheets S are pressed against the stopper  225  by using the first paddle  25   a , the sheets S may sometimes be pressed too much. In this case, the sheets S are pressed against the stopper  225 , and move in the sheet transport direction D by a repulsive force. Thus, the longitudinal alignment processing on the sheets S may not be executed accurately. In this regard, after the sheets S are pressed by the first paddle  25   a , the sheets S are pressed again by the second paddle  25   b . Thus, the longitudinal alignment processing is executed again on the sheets S on which the sufficient longitudinal alignment processing is not performed by using the first paddle  25   a , and the alignment state may be more accurate in the sheet transport direction. 
       FIG. 11  is a view showing that, after the longitudinal alignment processing is performed by using the second paddle  25   b , the paddle member  25  is further rotated in the A direction, and the longitudinal alignment processing is executed again by using the first paddle  25   a.    
     The first paddle  25   a , which is still bent, rotates in the arrow-A direction, and thereby moves the sheets S to the stopper  225  such that the longitudinal alignment processing is performed. Thereafter, the rotating first paddle  25   a  and second paddle  25   b  stop again at the first stop position (see  FIG. 9 ). 
       FIG. 12  is a view showing that the second paddle  25   b  presses the bundle of the plurality of sheets S. 
     The post-processing controller  24  further rotates the paddle member  25  (the first paddle  25   a  and the second paddle  25   b ) stopped at the first stop position (see  FIG. 9 ) from the first stop position in the arrow-A direction, and stops the paddle member  25  at a second stop position. At the second stop position, the end of the second paddle  25   b  comes in contact with the bundle of the plurality of sheets S on which the longitudinal alignment processing is applied, and is bent. Further, at the second stop position, the first paddle  25   a  is not protruded from the paddle guide  29 .  FIG. 13  is a view showing that subsequent sheets S′ are to be received where the second paddle  25   a  is in contact with the plurality of sheets S (at the second stop position). The first paddle  25   a  is stopped at the second stop position, and it is thus possible to transport the subsequent sheets S′ to the processing tray  221  while holding the sheets S pressed by the second paddle  25   b . The transport rollers  33   a  and  33   b  transport the sheets S′ to the processing tray  221 . 
       FIG. 14  is a view showing the first paddle  25   a  and the second paddle  25   b  return to the standby position. The first paddle  25   a  and the second paddle  25   b  of the state shown in  FIG. 13  (at the second stop position) further rotate in the arrow-A direction to the standby position. As a result, a series of operations is completed. 
       FIG. 15  is a flowchart showing a control of the rotation operation of the paddle members  25  (the first paddle  25   a  and the second paddle  25   b  ) shown in  FIG. 6  to  FIG. 14  executed by the post-processing controller  24 . Note that when operations and processing common to the first paddle  25   a  and the second paddle  25   b  are described below, the first paddle  25   a  and the second paddle  25   b  are simply referred to as the paddle member  25  (or paddle members  25 ) for convenience. In other words, when the term paddle member  25  is used, the paddle member  25  means both of the first paddle  25   a  and the second paddle  25   b.    
     The post-processing controller  24  drives the paddle motor  28  in a positive direction to rotate the first paddle  25   a  and the second paddle  25   b  in the arrow-A direction (counterclockwise direction) about the rotating shaft  26 . Further, the post-processing controller  24  drives the paddle motor  28  in the direction opposite to the positive direction to rotate the first paddle  25   a  and the second paddle  25   b  clockwise around the rotating shaft  26 . 
     First, when the plurality of sheets S are retained on the standby tray  211 , the post-processing controller  24  drives the paddle motor  28  in the positive direction to rotate the paddle members  25  from the standby position shown in  FIG. 6  to the arrow-A direction in Act 101  in  FIG. 15 . 
     In Act 102 , the post-processing controller  24  causes the paddle members  25  to come in contact with the sheets S. The first paddle  25   a  comes in contact with the sheets moving from the standby tray  211  to the processing tray  221 , and assists the sheets S to move faster to processing tray  221  (see  FIG. 7 ). 
     In Act 103 , the post-processing controller  24  keeps on rotating the paddle members  25 , and allows the first paddle  25   a  to execute the longitudinal alignment processing. The first paddle  25   a  executes the longitudinal alignment processing on the sheets S moved to the processing tray  221  (see  FIG. 8 ). In other words, the first paddle  25   a  comes in contact with the sheets S on the processing tray  221 , moves the sheets S to the stopper  225 , and presses the sheets S against the stopper  225 . Therefore the first paddle  25   a  accurately aligns the ends of the sheets S in the sheet transport direction D. Thus, the first paddle  25   a  executes the longitudinal alignment processing. 
     In Act 104 , the post-processing controller  24  determines whether or not the paddle members  25  rotate by a predetermined angle θ 1  from the standby position (see  FIG. 6 ). When the post-processing controller  24  determines that the paddle members  25  rotate by the predetermined angle θ 1  (Yes in Act 104 ), the processing of the post-processing controller  24  proceeds to Act 105 . In Act 105 , the post-processing controller  24  stops the rotation of the paddle members  25 . As a result, the paddle members  25  stop at the first stop position (see  FIG. 9 ). When the post-processing controller  24  determines that the paddle members  25  are yet to rotate by the predetermined angle θ 1  (No in Act 104 ), the post-processing controller  24  keeps on rotating the paddle members  25 . 
     In Act 106 , the post-processing controller  24  determines whether or not a predetermined time elapses after the rotation of the paddle members  25  is stopped in Act 105 . 
     When the post-processing controller  24  determines that the predetermined time is yet to elapse (No in Act 106 ), the post-processing controller  24  stands by until the predetermined time elapses. When the post-processing controller  24  determines that the predetermined time elapses (Yes in Act 106 ), the processing of the post-processing controller  24  proceeds to Act 107 . In Act 107 , the post-processing controller  24  rotates again the paddle members  25 . The paddle members  25  are driven by the paddle motor  28 , and rotate from the first stop position (see  FIG. 9 ) in the arrow-A direction (counterclockwise). 
     In Act 108 , the post-processing controller  24  keeps on rotating the paddle members  25 , and allows the second paddle  25   b  to execute the longitudinal alignment processing, as shown in  FIG. 10 . 
     Further, in Act 109 , the post-processing controller  24  keeps on rotating the paddle members  25 , and allows the first paddle  25   a  to execute again the longitudinal alignment processing, as shown in  FIG. 11 . 
     In Act 110 , the post-processing controller  24  determines whether or not the paddle members  25  rotate by a predetermined angle θ 2  from the standby position (see  FIG. 6 ). When the post-processing controller  24  determines that the paddle members  25  rotate by the predetermined angle θ 2  (Yes in Act 110 ), the processing of the post-processing controller  24  proceeds to Act 111 . In Act 111 , the post-processing controller  24  stops again the rotation of the paddle members  25 . As a result, the paddle members  25  stop again at the first stop position (see  FIG. 9 ). 
     Next, in Act 112 , the post-processing controller  24  rotates the paddle members  25  by a predetermined angle θ 3  from the first stop position (see  FIG. 9 ), and stops the rotation of the paddle members  25 . The second paddle  25   b  rotates by the predetermined angle θ 3 , and then stops at the second stop position, where the second paddle  25   b  comes in contact with the sheets S on the processing tray  221  (see  FIG. 12 ). The second paddle  25   b  is formed of an elastic material such as rubber and resin, and thus presses the sheets on the processing tray  221  at the second stop position in the bent state. As a result, the aligned sheets, on which the longitudinal alignment processing and the lateral alignment processing are applied, are not to be misaligned. In the second stop position, the first paddle  25   a  is located at the position that does not inhibit the subsequent sheets S′ from transporting to the processing tray  221  (for example, see  FIG. 13 ). Absolute values of the angles θ 1 , θ 2 , and θ 3  have a relationship represented by θ 3 &lt;θ 1 &lt;θ 2 . 
     In Act 113 , the post-processing controller  24  determines whether or not the sheet processed in Act 112  is the final sheet. When the post-processing controller  24  determines that the sheet processed in Act 112  is not the final sheet (No in Act 113 ), the processing of the post-processing controller  24  proceeds to Act 115 . In Act 115 , the post-processing controller  24  stands by for receiving the subsequent sheets S′ on the processing tray  221 . Here, when the subsequent sheets S′ are transported to the processing tray  221 , the front ends of the subsequent sheets S′ may come in contact with the sheets S on the processing tray  221  and the sheets S, on which the alignment processing is already applied, may be misaligned. 
     However, in this embodiment, the second paddle  25   b  presses the sheets S after the alignment processing. As a result, even if the front ends of the subsequent sheets S′ come in contact with the processing tray  221 , the aligned sheets S may not to be misaligned. 
     It should be noted that the post-processing controller  24  controls the transport rollers  33   a  and  33   b  in Act 115 , and transports the subsequent sheets S′ to the processing tray  221 . After the subsequent sheets S′ are transported to the processing tray  221 , the processing of the post-processing controller  24  returns to Act 101 . In Act 101 , the post-processing controller  24  rotates again the paddle members  25  in the arrow-A direction (counterclockwise), and guides the subsequent sheets S′ to the processing tray  221 . Then, the post-processing controller  24  executes the processing in Act 102  to Act 113  as described above. 
     Meanwhile, when the post-processing controller  24  determines that the sheet processed in Act 112  is the final sheet (Yes in Act 113 ), the processing of the post-processing controller  24  proceeds to Act 114 . In Act 114 , the post-processing controller  24  moves the paddle members  25  to the standby position. A series of processing is completed. 
     According to this embodiment, the sheets S on which the alignment processing is already executed are pressed by the second paddle  25   b , and it is therefore possible to prevent the sheets S on the processing tray from being misaligned. 
     Next, a second embodiment will be described with reference to  FIG. 16  and  FIG. 17 . In the second embodiment, stapling processing is performed by the stapler  222  where the plurality of sheets S on the processing tray  221  are pressed by the paddle members  25 . 
       FIG. 16  is a view showing a relationship among the paddle members  25 , the first alignment plate  51   a , and the second alignment plate  51   b  on the processing tray  221 . 
     The lateral alignment member  51  (including the first alignment plate  51   a  and the second alignment plate  51   b  ) is moved to the standby position, a first alignment position, and a second alignment position on the processing tray  221 . 
     The standby position is the position of the first alignment plate  51   a  and the second alignment plate  51   b  that receive the sheets S discharged from the transport rollers  33   a  and  33   b , or the sheets S moved from the standby tray  211 . It should be noted that the position of the first alignment plate  51   a  and the second alignment plate  51   b  in  FIG. 16  shows the standby position. 
     The first alignment position is the position where the first alignment plate  51   a  and the second alignment plate  51   b,  which have moved in the direction orthogonal to the sheet transport direction with reference to the center of the processing tray  221 , align the sheets S. Further, the distance between the first alignment plate  51   a  and the second alignment plate  51   b  at the first alignment position is preset slightly longer than the length of the sheets S to be aligned in the width direction. 
     The second alignment position is the position where the first alignment plate  51   a  and the second alignment plate  51   b,  which have moved in the direction orthogonal to the sheet transport direction with reference to the center of the processing tray  221 , align the sheets S. Further, the distance between the first alignment plate  51   a  and the second alignment plate  51   b  at the second alignment position is preset the same as or slightly shorter than the length of the sheets S to be aligned in the width direction. 
     It should be noted that, with reference to  FIG. 16 , the X coordinate value=0 indicates the center of the processing tray  221 . Further, at the standby position, the first alignment position, and the second alignment position, the first alignment plate  51   a  and the second alignment plate  51   b  are symmetric about the center of the processing tray  221 . 
     To illustrate the respective positions of the first alignment plate  51   a  and the second alignment plate  51   b ,  FIG. 16 , in the lower part, shows values −X 3 , −X 2 , −X 1 , X 1 , X 2 , and X 3  with reference to the center (X coordinate=0) of the processing tray  221 . Further, Table 1 shows the X coordinate values when the first alignment plate  51   a  and the second alignment plate  51   b  are placed at each operation position. It should be noted that the center of the processing tray  221  has the X coordinate value=0. Further, X 1 , X 2 , and X 3  have a relationship represented by X 1 &lt;X 2 &lt;X 3 . 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                   
                 Position of X 
               
               
                   
                 Position 
                 Member 
                 coordinate in FIG. 16 
               
               
                   
                   
               
             
            
               
                   
                 Standby 
                 First alignment 
                 X3 
               
               
                   
                 position 
                 plate 
               
               
                   
                   
                 Second alignment 
                 −X3  
               
               
                   
                   
                 plate 
               
               
                   
                 First alignment 
                 First alignment 
                 X2 
               
               
                   
                 position 
                 plate 
               
               
                   
                   
                 Second alignment 
                 −X2  
               
               
                   
                   
                 plate 
               
               
                   
                 Second alignment 
                 First alignment 
                 X1 
               
               
                   
                 position 
                 plate 
               
               
                   
                   
                 Second alignment 
                 −X1  
               
               
                   
                   
                 plate 
               
               
                   
                   
               
            
           
         
       
     
     Specifically, when the lateral alignment member  51  is at “the standby position”, the X coordinate value of the first alignment plate  51   a  is X 3 , and the X coordinate value of the second alignment plate  51   b  is −X 3 . 
     When the lateral alignment member  51  is at the first alignment position, the X coordinate value of the first alignment plate  51   a  is X 2 , and the X coordinate value of the second alignment plate  51   b  is −X 2 . The first alignment plate  51   a  and the second alignment plate  51   b  at the first alignment position are closer to the center of the processing tray  221  than they are at the standby position. The first alignment plate  51   a  and the second alignment plate  51   b  facing each other come in contact with the plurality of sheets S at the first alignment position, and align the ends of the sheets in the sheet width direction. 
     When the lateral alignment member  51  is at the second alignment position, the X coordinate value of the first alignment plate  51   a  is X 1 , and the X coordinate value of the second alignment plate  51   b  is −X 1 . At the second alignment position, the first alignment plate  51   a  and the second alignment plate  51   b  are symmetric about the center of the processing tray  221 , and are closer to the center of the processing tray  221  than they are at “the standby position” and than they are at “the first alignment position”. The first alignment plate  51   a  and the second alignment plate  51   b  facing each other come in contact with the plurality of sheets S at “the second alignment position”, and further align the ends of the sheets in the sheet width direction. 
       FIG. 17  is a flowchart showing a sheet press operation of the paddle members  25  executed by the post-processing controller  24 . It should be noted that the description common to the first embodiment will be simplified. 
     First, when the plurality of sheets S are retained on the standby tray  211  in Act 201 , the post-processing controller  24  drives the first tray member  211   a  and the second tray member  211   b  to separate from each other. The plurality of sheets S move from the standby tray  211  to the processing tray  221 . Further, the post-processing controller  24  rotates the paddle members  25  from the standby position (see  FIG. 6 ). The paddle members  25  is driven by the paddle motor  28  to start to rotate in the arrow-A direction. The first paddle  25   a  comes in contact with the sheet that moves from the standby tray  211  to the processing tray  221  (see  FIG. 7 ). 
     Next, the post-processing controller  24  drives the first alignment plate  51   a  and the second alignment plate  51   b  in Act 202 . The first alignment plate  51   a  and the second alignment plate  51   b , which are at the standby position of the lateral alignment member described above, start to move to the first alignment position. 
     In Act 203 , the post-processing controller  24  keeps on rotating the paddle members  25  to allow the first paddle  25   a  to execute the longitudinal alignment processing, as shown in  FIG. 8 . 
     In Act 204 , when the post-processing controller  24  determines that the paddle members  25  rotate by the predetermined angle θ 1 , then the post-processing controller  24  stops the rotation of the paddle members  25 . The first paddle  25   a  and the second paddle  25   b  stop at the first stop position, where the first paddle  25   a  and the second paddle  25   b  are separated from the processing tray  221  (see  FIG. 9 ). 
     In Act 205 , the post-processing controller  24  stops the first alignment plate  51   a  and the second alignment plate  51   b  at the first alignment position. Here, the paddle members  25  are separated from the plurality of sheets S on the processing tray  221 . Thus, the first alignment plate  51   a  and the second alignment plate  51   b  can execute the lateral alignment processing with being unaffected by the paddle members  25 . 
     In Act 206 , the post-processing controller  24  determines that the predetermined time elapses after the rotation of the paddle members  25  are stopped, and then rotates again the paddle members  25  in the arrow-A direction. 
     In Act 207 , the post-processing controller  24  allows the second paddle  25   b  to execute the longitudinal alignment processing, as shown in  FIG. 10 . Here, the first alignment plate  51   a  and the second alignment plate  51   b  are placed at the first alignment position. As a result, the sheets may not be misaligned in the sheet width direction when the longitudinal alignment processing is performed by using the second paddle  25   b.    
     In Act 208 , the post-processing controller  24  moves the second alignment plate  51   b  from the first alignment position to the second alignment position, and stops the second alignment plate  51   b  when it reaches the second alignment position. 
     Further, in Act 208 , the post-processing controller  24  keeps on rotating the paddle members  25 . In Act 209 , the post-processing controller  24  allows the first paddle  25   a  to execute again the longitudinal alignment processing on the sheets S on the processing tray  221  (see  FIG. 11 ). 
     In Act 210 , the post-processing controller  24  moves the first alignment plate  51   a  from the first alignment position to the second alignment position, and stops the first alignment plate  51   a  when it reaches the second alignment position. The first alignment plate  51   a  and the second alignment plate  51   b  facing each other come in contact with the plurality of sheets S, and execute further the lateral alignment processing. 
     Next, in Act 211 , when the post-processing controller  24  determines that the paddle members  25  rotate by the predetermined angle θ 2  from the standby position (see  FIG. 6 ), the post-processing controller  24  stops the rotation of the paddle members  25 . The rotating first paddle  25   a  and second paddle  25   b  stop again at the first stop position (see  FIG. 9 ). 
     Next, in Act 212 , after the predetermined time elapses, the post-processing controller  24  rotates the paddle members  25  by the predetermined angle θ 3  from the first stop position (see  FIG. 9 ), and stops the paddle members  25  at the second stop position where the sheets S are pressed. At the second stop position, the end of the second paddle  25   b  comes in contact with the sheets on the processing tray  221 . The second paddle  25   b  is formed of an elastic material, and thus presses the plurality of sheets S on the processing tray  221  while it is in the bent state (see  FIG. 12 ). It should be noted that the first paddle  25   a  is at the second stop position, where the transport of the subsequent sheets S is not hindered (see  FIGS. 12 and 13 ). 
     In Act 213 , the post-processing controller  24  determines whether or not the sheet processed in Act 212  is the final sheet. When the post-processing controller  24  determines that the sheet processed in Act 212  is not the final sheet (No in Act 213 ), the processing of the post-processing controller  24  proceeds to Act 217 . In Act 217 , the post-processing controller  24  moves the first alignment plate  51   a  and the second alignment plate  51   b  until they reach the standby position (see  FIG. 10 ). Then the post-processing controller  24  stands by for receiving the subsequent sheets S′ on the processing tray  221 . The subsequent processing of the post-processing controller  24  is similar to that in Act 201  to Act 213  described above, and description thereof is therefore omitted. 
     In Act 212 , when the post-processing controller  24  determines that the sheet processed in Act 212  is the final sheet (Yes in Act 213 ), processing of the post-processing controller  24  proceeds to Act 214 . In Act 214 , the post-processing controller  24  moves the first alignment plate  51   a  and the second alignment plate  51   b  toward the standby position (see  FIG. 10 ) in order to execute stapling processing by the stapler  222 . The first alignment plate  51   a  and the second alignment plate  51   b  move from the second alignment position to the standby position. 
     Here, the distance between the first alignment plate  51   a  and the second alignment plate  51   b  at the second alignment position is set slightly shorter than the length of the sheets S to be aligned in the width direction. Thus, when the first alignment plate  51   a  and the second alignment plate  51   b  execute the lateral alignment processing on the sheets S, the sheets are bent temporarily. When the first alignment plate  51   a  and the second alignment plate  51   b  are separated from the sheets S after the lateral alignment processing, the aligned sheets may sometimes be misaligned by a restoring force of the sheets. However, since the second paddle  25   b  presses the sheets S on the processing tray  221 , the aligned sheets S may not to be misaligned. 
     In Act 215 , the post-processing controller  24  controls the stapler  222  to execute stapling processing on the plurality of sheets S pressed by the second paddle  25   b . The stapler  222  can execute the stapling processing where the second paddle  25   b  presses the sheets S on the processing tray  221 , and the bundle of the well-aligned sheets may thus be obtained. 
     In Act 216 , after the stapling processing is executed, the post-processing controller  24  rotates the paddle members  25  to the standby position (see  FIG. 6 ). As a result, a series of operations is completed. 
     According to the second embodiment, the stapling processing is executed where the second paddle  25   b  presses the sheets S on the processing tray  221 , and the bundle of the well-aligned sheets may thus be obtained. Further, after the longitudinal alignment processing and the lateral alignment processing are executed a plurality of times, the sheets may be still aligned well since the second paddle  25  presses the sheets. 
     Further, as shown in  FIG. 16 , the rear ends of the sheets are pressed by the plurality of second paddles  25   b  attached along the rotating shaft  26 . Even if any external force is applied to the sheets, the aligned sheets are not to be misaligned. 
     Next, with reference to  FIG. 18 , a third embodiment will be described. According to the third embodiment, the stapling processing is executed at one spot or two spots by the stapler  222  where the plurality of sheets S on the processing tray  221  are pressed by the paddle members  25 . 
     It should be noted that the processing in Act 201  to Act 213  executed by the post-processing controller  24  of the third embodiment is the same as that of the second embodiment, and processing on and after Act 214  of the third embodiment is different that of the second embodiment. 
       FIG. 18  is a flowchart showing an operation of the stapling processing at one spot or two spots executed by the stapler  222  controlled by the post-processing controller  24 . The processing in Act 201  to Act 213  is common to the second embodiment, and description thereof is therefore omitted. 
     After the processing in Act 201  to Act 213  is executed, the post-processing controller  24  determines whether a job instructed by the image-forming controller  16  is a stapling job at one spot or a stapling job at two spots in Act 301 . 
     When the post-processing controller  24  determines that the job instructed by the image-forming controller  16  is the stapling job at one spot (stapling at one spot in Act 301 ), the processing of the post-processing controller  24  proceeds to Act 302 . In Act 302 , the post-processing controller  24  moves the first alignment plate  51   a  to the standby position. 
     In Act 303 , the post-processing controller  24  allows the stapler  222  to execute the stapling processing. 
     In Act 304 , the post-processing controller  24  moves the paddle members  25  until the paddle members  25  reach the standby position (see  FIG. 6 ), and discharges the bundle of the sheets stapled at one spot to the movable tray  23   b . A series of processing is completed. 
     When the post-processing controller  24  determines that the job instructed by the image-forming controller  16  is the stapling job at two spots (stapling at two spots in Act 301 ), the processing of the post-processing controller  24  proceeds to Act 305 . In Act 305 , the post-processing controller  24  moves the first alignment plate  51   a  to the standby position. 
     In Act 306 , the post-processing controller  24  allows the stapler  222  to execute the stapling processing on the plurality of sheets S at the first spot. 
     In Act 307 , the post-processing controller  24  moves the paddle members  25  to the standby position (see  FIG. 6 ). 
     As a result, it is possible to execute promptly the processing on next sheets after the stapling processing is completed, which contributes to enhance the total processing speed of the sheet post-processing apparatus. Further, since the stapling processing is executed at the first spot in Act 306 , the plurality of aligned sheets S are not misaligned largely even if the sheets S are not pressed by the buddle members  25 . 
     In Act 308 , the post-processing controller  24  moves the second alignment plate  51   b  to the standby position. 
     Further, in Act 308 , the post-processing controller  24  moves the stapler  222  to the second stapling processing spot. 
     Next, in Act 309 , the post-processing controller  24  controls the stapler  222  to execute the stapling processing at the second spot. The stapler  222  executes the stapling processing at the second spot on the bundle of the sheets, on which the stapling processing has been executed at the first spot. After that, the post-processing controller  24  discharges the bundle of the sheets stapled at the two spots to the movable tray  23   b . A series of processing is completed. 
     It should be noted that, description has been made in the first to third embodiments with reference to an example in which the sheets on the processing tray  221  are pressed by the second paddle  25   b . However, the scope of the present invention is not limited thereto. Thus, the sheets on the processing tray  221  may alternatively be pressed by the first paddle  25   a . When the first paddle  25   a  presses the sheets on the processing tray  221 , it is no need to execute the alignment processing by using the first paddle  25   a  for a plurality of times, which contributes to enhance the total processing speed of the sheet post-processing apparatus. 
     Further, in the first to third embodiments, the puddle member is rotated twice. However, the embodiment is not limited thereto. Specifically, after the longitudinal alignment processing is executed on the sheets on the processing tray  221  by using the first paddle  25   a , the sheets on which the longitudinal alignment processing is applied may be pressed by the second paddle  25   b . In this case, it contributes to further enhance the total processing speed of the sheet post-processing apparatus. 
     While certain embodiments have been described, these 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.