Abstract:
A sheet handling device has a sheet-aligning rotary member with an ejection device for ejecting sheets into a sheet stacking device, a sheet end stopper for holding the end of the sheet stacked in the sheet stacking device; and at least one rotary member for aligning the sheets ejected in the sheet stacking device with the sheet end stopper. The rotary member has an arc-shape outer peripheral surface around a portion of a circumference of said at least one rotary member.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sheet handling device having a sheet-aligning rotary member, and more particularly, to a sheet post-handling device that sequentially receives sheets of copy paper and the like ejected from an image forming apparatus, such as a copying machine, a printer, or a laser beam printer, after image formation, and subjects the sheets to processes, such as alignment and binding, and ejects and stacks the sheets in a stacking section. 
     2. Description of the Related Art 
     In image forming apparatuses, such as printing machines, copying machines, and printers, sheets are conveyed for image formation, and are ejected and stacked in an ejection tray after image formation. For the purpose of stacking in alignment, the ejected sheets are aligned in the sheet width direction by a regulating means that is movable in that direction, and are aligned in the sheet feeding direction by a rotary paddle returning the sheet so as to contact an abutting section. 
     When the sheets are aligned in the sheet feeding direction by a rotary paddle, the amount of deflection of the rotary paddle increases as the number of sheets to be stacked increases, which also increases the contact pressure between the rotary paddle and the sheets. As a result, the sheets may buckle when in contact with the abutting section, or overload may be imposed on the motor. 
     If the contact pressure is set to be small so that the stacked sheets do not buckle, even when the number of sheets increases, since the returning force decreases, it is necessary to increase the number of revolutions of the rotary paddle, and to turn the rotary paddle a multiple number of turns to align a single sheet. This may result in insufficient time to align the sheets in the sheet width direction. Moreover, since the sheets are aligned in the sheet width direction while in contact with the rotary paddle, the alignment in the sheet width direction may not be smooth. 
     The rotary paddle produces the returning force from stiffness of the paddles. Since the paddles are generally made of resin material, such as polyurethane, stiffness is likely to change with environmental changes, such as temperature changes, thereby making the contact pressure unstable. Furthermore, when curled paper or the like is aligned by the paddles, the rear end of the paper may be caught by the guide surface of the paddle, which results in alignment failure. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the above problems, and an object of the present invention is to provide a sheet handling device and an image forming apparatus equipped with a sheet-aligning rotary member having superior aligning ability. 
     According to one aspect of the present invention, there is provided a sheet handling device including: a sheet stacking device; an ejection device for ejecting sheets to the sheet stacking device; at least one rotary member having an arc-shaped outer peripheral surface around a portion of its circumference; and a sheet end stopper for holding the ends of the sheets stacked in the sheet stacking device. 
     The rotary member may be movable in a direction substantially perpendicular to a sheet stacking surface of the sheet stacking device. 
     In accordance with one aspect of the invention, the rotary member includes a rotation shaft, a support member for supporting the rotation shaft in engagement therewith, a guide portion provided in the support member, and a slide guide device in engagement with the guide portion so as to support the support member slidably in a direction substantially perpendicular to the sheet stacking surface of the sheet stacking device. 
     In accordance with another aspect of the invention, when the circumferential length of the arc-shaped outer peripheral surface of the rotary member is l 1 , the length from a contact point between the sheet stacking surface of the sheet stacking device and the outer peripheral surface of the rotary member to the sheet end stopper is l 2 , and the length from an intersection of a line perpendicularly extending from the outer peripheral surface of the ejection device on the downstream side and the sheet stacking surface of the sheet stacking device to the sheet end stopper is l 3 , l 1 ≧l 2  and l 2 ≧l 3 . 
     In accordance with still another aspect of the invention, the rotary member has a turning center on the outer peripheral side with respect to the rotation center. Furthermore, the rotary member has a support portion fixed to the rotation center, and an outer peripheral portion supported by the support portion so as to turn on the turning center with respect to the support portion. 
     A positioning portion may be provided in the support portion so that the outer peripheral portion aligns with a circle formed when the rotary member turns, and an urging device may be provided to urge the outer peripheral portion toward the positioning portion. 
     At least one of the rotary members may have a high-friction member on the outer peripheral surface thereof. The high-friction member may be detachable from the rotary member, and may be provided at at least two points symmetrical with respect to the ejection center of the sheets to be ejected from the ejection device. The high-friction member may be made of rubber. 
     According to another aspect of the present invention, there is provided an image forming apparatus comprising image forming means for forming an image on a sheet and a sheet handling device, including: a sheet stacking device; an ejection device for ejecting sheets with an image formed thereon to the sheet stacking device; at least one rotary member placed above the sheet stacking device and having an arc-shaped outer peripheral surface around a portion of a circumference of the rotary member; and a sheet end stopper for holding the ends of the sheets stacked in the sheet stacking device. 
     According to the above configuration, since the nearly arc-shaped rotary member is turned in contact with the stacked sheets, the amount of return of the sheets can be increased, and a single sheet can be aligned by one turn of the rotary member, which reduces the number of revolutions of the motor. Moreover, this ensures sufficient time for alignment in the sheet width direction. Since the rotary member is arc-shaped, it can be retracted from the sheet stacking space after alignment in the sheet feeding direction, which allows the sheets to be smoothly aligned in the sheet width direction without imposing a load. 
     Furthermore, since the rotary member has the pressure portion for raking the sheet, whose end remains on the guide surface below the ejection rollers, onto the sheet stacking surface, even curled paper and the like can be reliably aligned. 
     Even when the number of sheets to be stacked on the stacking device increases or decreases, since the rotary member can move in the direction of thickness of the stacked sheets, the contact pressure thereof does not significantly change and is made uniform, which can conform to a large number of stacked sheets. 
     As described above, according to the present invention, since the arc-shaped rotary member is turned in contact with the stacked sheets, it is possible to increase the amount of movement of the sheets. 
     Since the length of the arc-shaped outer peripheral portion of the rotary member is longer than the distance from the sheet landing position to the sheet end stopper, the sheet can be reliably moved to the sheet end stopper by only one turn of the rotary member. 
     Since the rotary member is movable in the direction of thickness of the sheets, the amount of change in contact pressure due to changes in the number of stacked sheets can be reduced, or a constant and stable alignment amount can be ensured regardless of the number of sheets. 
     Furthermore, even if a sheet ejected from the ejection device leans on the lower guide, it can be raked by the raking portion provided in the rotary member. This allows the sheet to reliably land on the handling tray and to be moved to the sheet end stopper. 
     Since the driving-side ejection roller is placed in the upper part of the path, and the return roller is placed in a small space between the path and the post-handling tray, the device can be reduced in size. Since the outer peripheral portion of the return roller is turnable on another center, multiple stacked sheets can be smoothly returned without causing step-out. Since the return roller can retract inside the rear end guide during alignment in the sheet width direction, smooth alignment can be achieved without imposing load. In addition, since the rubber members of the return rollers are placed symmetrically with respect to the sheet ejection center, the sheets can be prevented from skewing during returning operation. Since the rubber members are detachable, maintenance is facilitated. 
     Further objects, features, and advantages of the present invention will be apparent from the following description of the preferred embodiments with reference to the attached drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an explanatory sectional view showing the configuration of a sheet post-handling device according to the present invention; 
     FIG. 2 is an explanatory sectional view showing the configuration of an image forming apparatus according to the present invention; 
     FIGS. 3A,  3 B, and  3 C are explanatory views of return rollers and a shift mechanism for aligning members provided in a post-handling tray; 
     FIGS. 4A,  4 B,  4 C, and  4 D are explanatory views showing the motions of the return roller and a stack ejection belt in the sheet post-handling device; 
     FIG. 5 is a cross-sectional view of a shift mechanism for a stack tray; 
     FIG. 6 is a cross-sectional view of the shift mechanism for the stack tray; 
     FIG. 7 is an explanatory view showing the standby positions of the aligning members in a non-sort mode and a sort mode in the sheet post-handling device; 
     FIG. 8 is an explanatory view showing an aligning operation in a staple mode in the sheet post-handling device; 
     FIGS. 9A and 9B are state views showing the operation of the return roller when multiple sheets are stacked; and 
     FIG. 10 is an assembly view of the return roller. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A sheet post-handling device and an image forming apparatus having the device according to the present invention will be described in detail with reference to the attached drawings. FIG. 1 is an explanatory sectional view showing the configuration of a sheet post-handling device according to the present invention, FIG. 2 is an explanatory sectional view showing the configuration of an image forming apparatus according to the present invention, FIGS. 3A,  3 B, and  3 C are explanatory views of return rollers and a shift mechanism for aligning members provided in a post-handling tray, FIGS. 4A,  4 B,  4 C, and  4 D are explanatory views showing the motions of the return roller and a stack ejection belt in the sheet post-handling device, FIG. 5 is a cross-sectional view of a shift mechanism for a stack tray, FIG. 6 is a cross-sectional view of the shift mechanism for the stack tray, FIG. 7 is an explanatory view showing the standby positions of the aligning members in a non-sort mode and a sort mode in the sheet post-handling device, FIG. 8 is an explanatory view showing an aligning operation in a staple mode in the sheet post-handling device, FIGS. 9A and 9B are state views showing the operation of the return roller when multiple sheets are stacked, and FIG. 10 is an assembly view of the return roller. 
     Referring to FIG. 1, a sheet post-handling device (finisher)  1  according to the present invention is connected to an image forming apparatus  300 . A recycle document feeder (RDF)  305  is mounted at the top of the image forming apparatus  300 . 
     In the image forming apparatus  300 , as shown in FIG. 2, documents are automatically fed by the recycle document feeder  305 , and images thereon are read by an image reading section  306 . According to the read image information, signals are sent from a controller (not shown) to a laser oscillator to emit laser light. 
     The laser light is reflected off a rotating polygon mirror  309 , onto reflecting mirrors  310 , and is applied onto an electrophotographic photoconductive drum  312  uniformly charged on its surface so as to serve as an image forming means, thereby forming an electrostatic latent image. The electrostatic latent image on the photoconductive drum  312  is developed by a developing device  311 , and is transferred as a toner image onto a sheet S that is formed of paper, an OHP sheet, or the like. 
     Sheets S are appropriately and selectively delivered from a sheet cassette  351  or  352  by a pickup roller  313  constituting a sheet feeding means, are separated one by one by a separation means  307 , and are conveyed to a pair of register rollers  314  and  315  by a pair of pre-register rollers  316  and  317 . The skewing of the sheet S is corrected by the register rollers  314  and  315 , and the sheet S is conveyed between the photoconductive drum  312  and a transfer device opposed thereto in synchronization with the rotation of the photoconductive drum  312 , where the toner image formed on the photoconductive drum  312  is transferred onto the sheet S by the action of the transfer device. 
     Subsequently, the sheet S is guided to a pair of fixing rollers  301  and  302 , and is subjected to heating and pressing by the fixing rollers  301  and  302 , whereby the toner image transferred onto the sheet S is permanently fixed. Upper and lower fixing separation claws  303  and  304  are in contact with the fixing rollers  301  and  302 , respectively, so as to separate the sheet S from the fixing rollers  301  and  302 . 
     The separated sheet S is conveyed out of the image forming apparatus  300  by a pair of ejection rollers  399 , and is guided to the sheet post-handling device  1  connected to the image forming apparatus  300 . 
     The sheet post-handling device  1  and the image forming apparatus  300  are connected by engaging a lock arm  2  at the top of the sheet post-handling device  1  with a holding member  3  of the image forming apparatus  300 . Furthermore, a slide unit  4  fixed to the image forming apparatus  300  is placed at the bottom of the sheet post-handling device  1 , and allows the sheet post-handling device  1  to move in a sheet ejecting direction (Y-direction in FIG.  1 ). In order to remove a sheet remaining inside the body of the image forming apparatus  300  or the sheet post-handling device  1  because of feeding failure or for other reasons, the sheet post-handling device itself is moved in the Y-direction by turning the lock arm  2  in the X-direction, so that it can be smoothly detached from the image forming apparatus  300 . 
     The sheet S ejected by the ejection rollers  399  is fed further downstream through a sheet path  7  formed by an upper guide  5  and a lower guide  6  in the sheet post-handling device  1 . A sheet detection sensor  8  serves to detect a sheet passing therethrough and to detect a jammed sheet. A pair of ejection rollers  9  consists of an ejection roller  9   a  and an ejection roller  9   b  in pressure contact with the ejection roller  9   a . In this embodiment, a driving shaft  9   c  is placed on the upper side so that return rollers are disposed in a small space below the sheet path  7 . 
     A post-handling tray  30  serving as a sheet stacking means is formed as an intermediate tray for temporarily collecting sheets and for subjecting the sheets to alignment and stapling. 
     A stapler  10  serves to staple a stack of sheets laid on the post-handling tray  30 . Although this stapler  10  is not further described in this embodiment, it has a structure similar to that of an automatic commercial stapling device that is electrically driven or motor-driven, and fastens the sheets with staples. 
     Stack ejection belts  60  serve to convey and eject sheets on the post-handling tray  30  in stacks into a stack tray  80 . 
     A post-handling tray unit  20  is disposed between the conveyor section for conveying sheets from the image forming apparatus  300  and the stack tray  80  for receiving and holding stacks of sheets that have been subjected to post-handling by the post-handling tray  30 . 
     The post-handling tray unit  20  comprises the post-handing tray  30 , an aligning device  40 , return rollers  50 , and the stack ejection belts  60 . 
     As shown in FIG. 1, the post-handling tray  30  is inclined so that the downstream side in the sheet feeding direction (the left side in FIG. 1) is placed on the upper side and the upstream side (the right side in FIG. 1) is placed on the lower side, and is provided with a rear end stopper  31  at the lower end thereof. 
     The sheet S ejected by the ejection rollers  9  slides on the post-handling tray  30  by its own weight and by the action of the return rollers  50 , which will be described later, until the rear end thereof impacts the rear end stopper  31 . 
     The post-handling tray  30  is also provided with the stack ejection belts  60 . The stack ejection belts  60  move in the sheet ejecting direction by the driving of a motor  70  so as to eject stacks of sheets on the post-handling tray  30  into the stack tray  80 . 
     Next, the aligning device  40  will be described with reference to FIG.  3 A. Dashed line C represents the sheet ejection center. Aligning members  41  and  42  on the front and rear sides of the aligning device  40  are independently movable in a direction orthogonal to the sheet feeding direction (in the sheet width direction). The aligning members  41  and  42  respectively include aligning surfaces  41   a  and  42   a  standing on the post-handling tray  30  so as to regulate both sides of sheets S in abutting contact therewith, and rack gears  41   b  and  42   b  extending in the direction of width of the post-handling tray  30 . 
     The aligning members  41  and  42  are mounted so that the aligning surfaces  41   a  and  42   a  are placed above the post-handling tray  30  and the rack gears  41   b  and  42   b  are placed below the post-handling tray  30 . 
     The rack gears  41   b  and  42   b  are meshed with separate pinion gears  43  and  44  that are connected to separate motors  45  and  46  via gears and the like (not shown). 
     According to the above structure, the pinion gears  43  and  44  are turned by forward and reverse rotations of the motors  45  and  46 , and the rack gears  41   b  and  42   b  meshed with the pinion gears  43  and  44  move to shift the aligning members  41  and  42  in the direction of the width of the sheets S. 
     The aligning members  41  and  42  are provided with sensors  48  and  49  for detecting the home positions thereof. Normally, the aligning members  41  and  42  stand by at the home positions. In this embodiment, the home position of the aligning member on the front side is set at the front limit, and the home position of the aligning member on the rear side is set at the rear limit. 
     Next, the return rollers  50  will be described with reference to FIGS. 3A to  3 C and  4 A to  4 D. As shown in FIG. 4A, the return rollers  50  have a substantially arc-shaped outer peripheral surface, and are fixed to a return roller shaft  51  so as to rock in a direction nearly orthogonal to the sheet stacking surface. The return rollers  50  are urged by springs  52  to form an arc centered on the return roller shaft  51 . 
     The return rollers  50  are mounted on the return roller shaft  51  at regular intervals in the sheet width direction, as shown in FIG.  3 A. Two of the return rollers  50 A, which are placed symmetrically with respect to the sheet ejection center, have friction members  53  made of silicone rubber or the like on the arc-shaped outer peripheral surfaces thereof, and the other return rollers  50 B do not have friction members  53 . 
     The return roller shaft  51  is supported by bearings  54  and  55  so as to turn relative to a front side plate  200  and a support section  201  and to move in the direction of a thickness of the sheets S laid on the post-handling tray  30 . The bearings  54  and  55  are provided with pressure springs  56  and  57 . FIG. 3B is a partly enlarged view of the components shown in FIG. 3A, and FIG. 3C is a view seen from the direction of arrow C in FIG.  3 B. The support section  201  is formed integrally with a rear end guide  100 . The front side plate  200  and the support section  201  have guide grooves  200   a  and  201   a  for vertically guiding the bearings  54  and  55 . 
     The return roller shaft  51  is connected to the motor  70  via a pulley  58  and a timing belt  59 . In response to driving by the motor  70 , the return rollers  50  turn together with, and are centered on, the return roller shaft  51  in the counterclockwise direction in FIGS. 4A to  4 D. 
     As shown in FIG. 4A, the home position of the return roller  50  is set so that the return roller  50  is not in contact with the sheets ejected into the post-handling tray  30  by the ejection rollers  9 . 
     When a sheet S is ejected from the ejection rollers  9 , the return rollers  50  turn one turn centered on the return roller shaft  51  in the counterclockwise direction by driving by the motor  70 , as shown in FIG. 4B, and pull the sheet S until the sheet S impacts the rear end stopper  31 . 
     If the ejected sheet S leans on the rear end guide  100 , the return rollers  50  catch the rear end of the sheet S by sheet raking portions  50   a  and turn one turn centered on the return roller shaft  51  counterclockwise while raking out the rear end of the sheet S, as shown in FIGS. 4A and 4B. Thereby the sheet S reliably lands on the post-handling tray  30  and is pulled to abut against the rear end stopper  31 . Subsequently, the return rollers  50  stop at the home positions, and wait for the next sheet S to be ejected. As shown in FIG. 4D, when the length of the arc of the return roller  50  is l 1 , the length from an intersection p 1  of the outer periphery of the return roller  50  and the sheet stacking surface of the post-handling tray  30  to the rear end stopper  31  is l 2 , and the length from an intersection p 2  of a line vertically extending downward from the outer peripheral surface of the ejection roller  9   b  and the sheet stacking surface, or an intersection p 2  of a line vertically extending downward from a vertical surface  100   a  of the rear end guide  100  and the sheet stacking surface to the rear end stopper  31  is l 3 , the formula l 1 ≧l 2  and l 2 ≧l 3  is satisfied. 
     Accordingly, the rear end of the sheet ejected from the ejection rollers  9  lands within the range of l 3  from the sheet stopper  31 , and the sheet is aligned by one turn of the return roller  50  corresponding to the length l 1  longer than the length l 3 . In the configuration of this embodiment, as shown in FIGS. 4A, the outer peripheral portion of the return roller  50  is completely retracted inside the rear end guide  100  at a predetermined stop position, where sheet alignment in the widthwise direction is performed by the aligning members  41  and  42 . Therefore, there is no load in alignment in the widthwise direction, and this allows for smooth sheet alignment. 
     As shown in FIGS. 9A and 9B, the return roller  50  is supported on the return roller shaft  51  by a support portion  50   d  so as to turn on a second fulcrum  50   b  in the direction of the arrow, and is urged in the direction of the arrow A by a spring  101  with respect to a stopper  50   c  provided in the support portion  50   d . Therefore, even when multiple sheets are stacked on the post-handling tray  30 , the return roller  50  turns counterclockwise, and the outer peripheral portion thereof contacts the upper surface of the sheets and retracts inside the periphery, as shown in FIG.  9 B. This allows the return roller  50  to turn smoothly, and achieves reliable sheet alignment without producing load and tension at the contact portion. 
     Since the two friction members  53  are placed symmetrically with respect to the sheet ejection center in this case, pressure is uniformly applied to the sheets so that the sheets can be aligned in a well-balanced manner without skewing. Even when multiple sheets are laid on the post-handling tray  30 , as shown in FIG. 4C, since the return roller shaft  51  itself can shift upward, the amount of return from one turn of return roller  50  can be stably ensured. Furthermore, in this embodiment, the friction members  53  have engaging recesses  53   a , as shown in FIG. 10, and are detachably mounted by engaging the engaging recesses  53   a  with engaging projections  50   e  formed in the return roller  50 . 
     Next, the stack ejection belt  60  will be described with reference to FIGS. 3A and 4A to  4 D. The stack ejection belt  60  has a hook portion  60   a , as shown in FIGS. 4A to  4 D, is looped over pulleys  61  and  62 , and is connected to the motor  70  via a gear  63 , a one-way gear  64 , and the timing belt  59 . The one-way gear  64  transmits the driving force to the gear  63  only when the motor  70  turns clockwise. 
     When the return roller  50  pulls the last sheet S so that the sheet S contacts the rear end stopper  31 , the stack ejection belt  60  moves along the inclination of the post-handling tray  30  in the direction of the arrow A in FIG. 4D (in the sheet feeding direction) in response to the driving by the motor  70 , and ejects the stack of sheets S, which have been aligned and stapled on the post-handling tray  30 , into the stack tray  80 . 
     Next, the structure of the stack tray  80  will be described with reference to FIGS. 5 and 6. The stack tray  80  has a sub-tray  79  built therein. By drawing the sub-tray  79  out, sheets of large sizes, for example, A 3  and B 4  sizes, can be stacked therein. 
     The stack tray  80  is supported by tray support plates  81  and  82  on both sides, and timing belts  83  and  84  are fixed to the tray support plates  81  and  82 . 
     The timing belt  83  is looped over pulleys  85  and  86 , and the timing belt  84  is looped over pulleys  87  and  88 . The pulleys  86  and  88  are fixed on a driving shaft  90  on which a driving gear  89  is fixed, and are connected to a driving motor  92  via a train of gears  91 . 
     The tray support plates  81  and  82  are provided with rollers  93  and  94  that are rotatable with respect to roller guides  95  and  96 . The rollers  93  and  94  move in the vertical direction (in the Z-direction in FIG. 5) along the roller guides  95  and  96  in response to driving by the driving motor  92 . 
     A sheet surface height detection sensor  97  serves to detect the height of a stack of sheets, and to adjust the height of the surface of the sheets stacked on the stack tray  80  with respect to the post-handling tray  30  to a predetermined height. 
     Next, description will be given of the travel of sheets S in the sheet post-handling device  1  with reference to FIGS. 1 and 7 to  10 . First, description will be given of an operation to be performed when a non-sort mode is selected by a user through a control section (not shown) in the body of the image forming apparatus  300 . When the user places a document on the recycle document feeder  305  and turns on a start key (not shown), an image is formed on a sheet S in the image forming apparatus  300 , and the sheet S is output from the ejection rollers  399  of the image forming apparatus  300 . Then, the ejection rollers  9  of the sheet post-handling device  1  turn to guide and carry the ejected sheet S in the sheet post-handling device  1 . 
     As shown in FIG. 7, when there is no sheet in the post-handling tray  30 , that is, when the first sheet S in a job is to be ejected, the aligning members  41  and  42  on the front and rear sides, which have been on standby at the home positions, move to the positions slightly offset outward from both sides of the sheet S (PS 11 , PS 21 ). 
     The ejected sheet S starts to move toward the rear end stopper  31  by its own weight. In addition, the return rollers  50  that are stopped at the home position turn counterclockwise in FIG. 1 in response to driving by the motor  70 , thereby promoting the movement of the sheet S toward the rear end stopper  31 . 
     When the rear end of the sheet S contacts the rear end stopper  31  and the sheet S reliably stops, the aligning member  42  on the rear side stays at a position PS 21  to serve as the reference, as shown in FIG.  7 . In contrast, the aligning member  41  on the front side moves to a position PS 12  to align the sheet S at the first aligning position. 
     Next, description will be given of an operation to be performed when the user selects a staple-and-sort mode. When the user places a document on the recycle document feeder  305  and turns on the start key (not shown), an image is formed on a sheet S in the image forming apparatus  300 , the ejection rollers  9  of the sheet post-handling device  1  turn, and the sheet S is ejected from the ejection rollers  399  of the image forming apparatus  300 . The ejected sheet S is guided to the sheet post-handling device  1 , is carried therein, and is ejected into the post-handling tray  30  by the ejection rollers  9 . 
     The ejected sheet S starts to move toward the rear end stopper  31  by its own weight. In addition, the return rollers  50  that have stopped at the home positions turn counterclockwise in FIG. 1 in response to driving by the motor  70 , thereby promoting the movement of the sheet S toward the rear end stopper  31 . 
     When the rear end of the sheet S contacts the rear end stopper  31  and the sheet S stops, the aligning member  41  stops at the home position, and the aligning member  42  carries and aligns the sheet S ejected on the rear end stopper  31  to a stapling position (FIG.  8 ). 
     When all the sheets in the first stack are ejected and aligned in the post-handling tray  30 , they are stapled by the stapler  10 . The sheets on the post-handling tray  30  are ejected in a stack onto the stack tray  80  by the stack ejection belts  60 . 
     While the present invention has been described with reference to what are presently considered to be the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.