Patent Publication Number: US-2007108689-A1

Title: Sheet processing apparatus and image forming apparatus

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a sheet processing apparatus and an image forming apparatus, particularly to a sheet processing apparatus and an image forming apparatus capable of discharging a residual sheet at turning on the power.  
      2. Description of the Related Art  
      Heretofore, some of image forming apparatuses such as a copying machine, a printer and a facsimile are provided with a sheet processing apparatus for relieving troublesome tasks required to perform such treatments as a stapling treatment and a punching treatment on sheets with images formed thereon. The sheet processing apparatus is designed to sequentially receive sheets with images formed thereon into the apparatus and selectively perform such treatments as the stapling treatment and the punching treatment on the sheets.  
      Now, the image forming apparatus, which is provided with such a sheet processing apparatus, performs initialization control at turning on the power such as driving-gear engagement check, high-transfer-voltage control, and scanner motor drive check. Then, after the treatments have been performed by such initialization control, the image forming apparatus enters into a standby mode, starts feeding sheets when receiving a printing request from external equipment connected, and performs image forming operation in accordance with a predetermined electrophotographic process.  
      Incidentally, a controlling portion of the image forming apparatus is adapted to control the apparatus, when detecting any residual sheets within a main body of the image forming apparatus at turning on the power, to enter into a jam clearance mode and wait for a predetermined jam clearance operation to be performed by a user.  
      Then, thereafter when, for example, a sensor detects that a door for jam clearance has been opened and closed by the user to perform the jam clearance, and a signal is transmitted to the controlling portion of the image forming apparatus through a sensor input portion, the controlling portion detects that the jam clearance has been performed based on the door open/close information. When the jam clearance has been completed by the user and the power is turned on again, the above-described initialization control is carried out and the apparatus enters into the standby mode.  
      On the other hand, as a conventional image forming apparatuses, there is one designed such that a sheet presence/absence detecting means is disposed in a sheet conveying path to detect a presence or absence of a residual sheet in the sheet conveying path, when carrying out the initialization operation to cause an image forming means to enter into a standby mode for enabling the image forming operation at turning on the power. Such image forming apparatus is designed so that, when any residual sheet is detected by the sheet presence/absence detecting means, the residual sheet is conveyed to a sheet processing apparatus during the initialization operation and discharged to a sheet discharge tray of the sheet processing apparatus (for example, refer to Japanese Patent Application Laid-Open No. H08-286586).  
      Now, when the residual sheet is conveyed as described above, the conventional sheet processing apparatus is designed to discharge the residual sheet to the sheet discharge tray, and is designed to convey and discharge the conveyed sheet in accordance with the sheet discharging speed of the main body of the image forming apparatus.  
      However, when a sheet is thus discharged in accordance with the sheet discharging speed of the main body of the image forming apparatus, a size of the sheet to be discharged is unknown. Therefore, for example, in the case where the sheet discharging speed is too fast relative to the sheet size, the sheets are unevenly stacked on the downstream side in the sheet discharge direction on the sheet discharge tray. Also, when the sheet is conveyed in a skewed state from the main body of the image forming apparatus, the sheet is stacked on the sheet discharge tray in the skewed state as is.  
      That is, since the conventional sheet processing apparatus, when discharging a residual sheet, discharges the sheet synchronously with the sheet discharging speed of the main body of the image forming apparatus without correcting the skew feed, stackability of sheet on the sheet discharge tray cannot be secured.  
     SUMMARY OF THE INVENTION  
      The present invention has been made in view of the above-described present situation. An object of the present invention is to provide a sheet processing apparatus and an image forming apparatus capable of securing stackability of a sheet when discharging a residual sheet.  
      An object of the present invention is to provide a sheet processing apparatus comprising: a first sheet stacking portion connected to a main body of an image forming apparatus for stacking thereon a sheet conveyed from the main body of the image forming apparatus; a second sheet stacking portion provided downstream of the first sheet stacking portion with respect to a sheet conveying direction for stacking thereon the sheet discharged from the first sheet stacking portion after being treated thereon; a trailing edge aligning portion for aligning a trailing edge in the sheet conveying direction of the sheet stacked on the first sheet stacking portion; a discharging member having a holding member for holding the sheet, the trailing edge of which has been aligned by the trailing edge aligning portion, and while holding the sheet by the holding member, moving the sheet to a sheet discharging position, in which the sheet is discharged onto the second sheet stacking portion by releasing the holding by the holding member; and a control device for controlling the discharging member in such a manner that, when a residual sheet remains in the main body of the image forming apparatus and the residual sheet is conveyed at turning on the power for the main body of the image forming apparatus, the trailing edge of the residual sheet is aligned by the trailing edge aligning portion, and then the discharging member is moved to the sheet discharging position while holding the residual sheet by the holding member.  
      Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a cross-sectional view showing the construction of an image forming apparatus provided with a sheet processing apparatus according to an embodiment of the present invention.  
       FIG. 2  illustrates the construction of the sheet processing apparatus.  
       FIG. 3  shows a manner in which a sheet is discharged onto a treatment tray of the sheet processing apparatus.  
       FIG. 4  illustrates a driving mechanism for an offset roller and a conveying roller of the sheet processing apparatus.  
       FIG. 5  illustrates a driving mechanism for the offset roller, the conveying roller, a sheet bundle discharging member and a sheet clamp member of the sheet processing apparatus.  
       FIGS. 6A and 6B  illustrate the operation of the offset roller and the resultant movement of the sheet.  
       FIG. 7  illustrates the operation of the sheet clamp member.  
       FIG. 8  shows a manner in which the sheet bundle discharging member discharges a sheet bundle onto a stack tray.  
       FIG. 9  is a block diagram showing the construction of a controlling portion of the sheet processing apparatus.  
       FIG. 10  is a flow chart illustrating a part of the sheet processing operation of the sheet processing apparatus and a main body of the image forming apparatus at turning on the power.  
       FIG. 11  is a flow chart illustrating the remainder of the sheet processing operation of the sheet processing apparatus and the main body of the image forming apparatus at turning on the power. 
    
    
     DESCRIPTION OF THE EMBODIMENTS  
      Embodiments of the present invention will be hereinafter described in detail with reference to the drawings.  
       FIG. 1  is a cross-sectional view showing a construction of an image forming apparatus provided with a sheet processing apparatus according to an embodiment of the present invention.  FIG. 1  shows an image forming apparatus A, a main body  500  of the image forming apparatus, an automatic original feeder (ADF)  300  installed on an upper face of the main body  500  of the image forming apparatus and a sheet processing apparatus  400  that processes sheets discharged from the image forming apparatus A.  
      In addition, in  FIG. 1 , a reader portion (image inputting device)  120  converts an image of an original into image data. A printer portion  200  which is an image forming portion has a plurality of types of sheet cassettes  204  and  205 , and outputs the image data as a visible image onto a sheet by a print command.  
      When in the image forming apparatus A of such a construction, an image of an original is to be read to thereby form an image, originals stacked on the automatic original feeder (ADF)  300  are adapted to be first conveyed sequentially one by one onto a platen glass surface  102 .  
      Next, when the original is thus conveyed to a predetermined position on the platen glass surface  102 , the lamp  103  of the reader portion  120  is turned on and a scanner unit  101  is moved and irradiates the original. Reflected light from this original is inputted to a CCD image sensor portion  109  through the intermediary of mirrors  105 ,  106 ,  107  and a lens  108 , and electrical processing such as photoelectric conversion is effected in this CCD image sensor portion  109 , and ordinary digital processing is effected.  
      Next, the image signal thus subjected to the electrical processing is converted into a modulated optical signal by the exposure controlling portion  201  of the printer portion  200 , and irradiates a photosensitive drum  202 . By this irradiating light, a latent image is formed on the photosensitive drum  202 , and this latent image is developed by a developing device  203  with a result that a toner image is formed on the photosensitive drum  202 .  
      Next, in timed relationship with the leading edge of this toner image, a sheet S is conveyed from the sheet cassette  204  or  205 , and in a transferring portion  206 , the toner image is transferred to the sheet S. Thereafter, the toner image transferred to the sheet S is fixed by a fixing portion  207 , and after the toner image has been thus fixed, the sheet S is discharged from a sheet discharging portion  208  to the outside of the image forming apparatus.  
      Then, the sheet S outputted from the sheet discharging portion  208  is conveyed to the sheet processing apparatus  400 , where a treatment such as sorting or stapling is effected in accordance with an operating mode designated in advance.  
      When images successively read in are to be outputted onto the two sides of a sheet S, the sheet S on one side of which the toner image has been fixed by the fixing portion  207  is first directed to a path  215  by a changeover member  209  being once changed over to a solid-line direction in  FIG. 1 , and is conveyed to a surface reverse path  212  via a path  218  by a direction changeover member  217  being changed over to a broken-line and a direction changeover member  213  being changed over to a broken-line direction.  
      Next, after the trailing edge of the sheet has passed the direction changeover member  213 , the direction changeover member  213  is changed over to a solid-line direction, and the rotational direction of a roller  211  is reversed to thereby direct the sheet to a path  210 , whereafter the sheet is conveyed to the transferring portion  206  so that an image may be formed on the back side of the sheet S.  
      On the other hand, the sheet processing apparatus  400  is provided with a stapling function which is a binding operation by the stapler unit, in addition to a sorting operation of sorting the sheet. As shown in  FIG. 2 , the sheet processing apparatus  400  is provided with a treatment tray  410  for treating the sheets S successively discharged from the main body  500  of the image forming apparatus, and a stack tray  421  for finally stacking thereon the sheet bundle treated on the treatment tray  410 . The sheet processing apparatus  400  is constructed to form a sheet bundle of the number of sheets corresponding to the number of originals on the treatment tray  410  exemplified as a first sheet stacking portion and discharge each sheet bundle to the stack tray  421  exemplified as a second sheet stacking portion.  
      In  FIG. 2 , a sheet receiving portion  401  receives the sheet S discharged from the main body  500  of the image forming apparatus. The sheet S received by this sheet receiving portion  401  is detected by an entrance sensor  403 , and thereafter is conveyed by a conveying roller  405  and an offset roller  407 , and thereafter, as shown in  FIG. 3 , is discharged onto the treatment tray  410 . The sheets S thus stacked on the treatment tray  410  have their presence or absence detected by a sheet bundle discharge sensor  415  shown in  FIG. 2 .  
      The entrance sensor  403  is a sheet detecting device for detecting the trailing edge of the sheet S conveyed from the main body  500  of the image forming apparatus.  
      The offset roller  407  is held for upward and downward movement by an offset roller arm  406  movable in a vertical direction about a shaft  406 a shown in  FIGS. 4 and 5 . This offset roller  407 , when it conveys the sheet S to the treatment tray  410 , is adapted to be moved to an upper position through the offset roller arm  406 , whereby the sheet S is conveyed onto the treatment tray  410  without being hindered by the offset roller  407 .  
      This offset roller arm  406  is movable up and down with the shaft  406   a  as a fulcrum by the pickup solenoid  433 . That is, the offset roller  407  is moved up and down by the ON/OFF of the pickup solenoid  433  through a down lever  433   a.    
      Also, this offset roller  407 , as shown in  FIG. 5 , is adapted to be driven by a conveying motor  431  which drives the conveying roller  405 , through belts  431   a  and  431   b,  and when the conveying motor  431  is rotated, the offset roller  407  is adapted to be rotated in the conveying direction, or rotated in a direction reverse to the conveying direction (hereinafter referred to as the reverse rotation), by an amount according to the amount of rotation of the conveying motor  431 .  
      Incidentally, in this embodiment, the pickup solenoid  433  is turned off before the sheet S has passed through the conveying rollers  405 . That is, timing when the pickup solenoid should be turned off is prescribed based on the movement amount of the sheet from the entrance sensor  403  (in the embodiment, 80 mm). Thereby, the offset roller  407  moves down with the aid of the gravitational force of the offset roller  407  and lands on the sheet, and thereafter is adapted to be rotated in the sheet conveying direction for a predetermined time, and to be reversely rotated when a predetermined time further elapses.  
      By the offset roller  407  being thus reversely rotated, the trailing edge of the sheet is abutted against a sheet trailing edge stopper  411  exemplified as a regulating member provided upright on the upstream end portion of the treatment tray  410  with respect to the conveying direction for regulating the trailing edge of the sheet S.  
      Incidentally, in this embodiment, a trailing edge aligning portion  408 , which aligns the trailing edge in the sheet conveying direction of the sheet stacked on the treatment tray  410 , is composed of the offset rollers  407  exemplified as a sheet conveying member, which can rotate forward and reversely, and the sheet trailing edge stopper  411 . The sheet S is aligned in the conveying direction by the trailing edge aligning portion  408 .  
      A positioning wall  416  as a side edge regulating member shown in  FIG. 4  regulates the position of the edge portion in a direction orthogonal to the sheet conveying direction of the sheet (hereinafter, referred to as width direction). A stapler unit  420  as a binding means is disposed near the positioning wall  416  of the treatment tray  410  and performs stapling treatment on a sheet bundle formed on the treatment tray  410 .  
      Incidentally, the offset rollers  407  move in the width direction being driven by an offset motor  432  as a driving means, which can rotate forward and reversely, through a rack  406   c  and a pinion  406   b.  Thereby, the offset rollers  407  are adapted to come closer to the positioning wall  416  or moves away therefrom. The offset motor  432  constitutes a moving means together with the offset rollers  407 .  
      Design is made such that when the offset roller  407  thus approaches the positioning wall  416 , the sheet abutted against the sheet trailing edge stopper  411  and aligned in the conveying direction is moved to the positioning wall  416  by the frictional force of the offset roller  407  and the positioning thereof in the width direction is effected. After the sheet S has been abutted against the positioning wall  416 , the offset roller  407  is adapted to be slidingly moved on the sheet and stopped.  
      Here, by such an offset roller  407  being provided, the sheet discharged onto the treatment tray  410  is conveyed to the stack tray side by the offset roller  407  rotated in the sheet conveying direction, as shown in FIG.  6 A, whereafter as shown in  FIG. 6B , the sheet is returned to the sheet trailing edge stopper  411  by the reverse rotation of the offset roller  407 , and thereafter has its trailing edge abutted against the sheet trailing edge stopper  411  and is aligned.  
      In  FIGS. 6A, 6B  and  7  which will be described later, unlike  FIG. 4  already described, description is made by the use of a construction in which the offset roller  407  is disposed inside the offset roller arm  406 , but this difference in construction is merely a difference simply in design. That is, there is no difference in function and action from the construction shown in  FIG. 4 .  
      On the other hand, a sheet clamp member  412  exemplified as a holding member shown in  FIG. 5  is adapted to hold down the trailing edge portion of the aligned sheet S from above it by the urging force of urging means (not shown). The sheet clamp member  412  is adapted so as to hold down the aligned sheet S from above it when the offset rollers  407  have been lifted up by the pickup solenoid  433  after completing the alignment in the width direction of the sheet S and the alignment of the tailing edge of the sheet S.  
      Thereby, the sheet S discharged (conveyed) earlier onto the treatment tray  410  can be held in a predetermined position without being subjected to the action such as an associated conveyance with a subsequent sheet S successively fed thereafter. Incidentally, the sheet clamp member  412  is rotated upward to receive the sheet S while the offset rollers  407  perform a reverse rotation as shown in  FIG. 7 .  
      The sheet bundle discharging member  413  exemplified as a discharging member shown in  FIG. 5  discharges a treated sheet bundle onto the stack tray  421 . The sheet bundle discharging member  413  holds the sheet clamp member  412  rotatably. Also, the sheet bundle discharging member  413  is adapted to move in a direction of the stack tray  421  provided downstream side of the treatment tray  410  shown in  FIG. 8  while holding a sheet bundle, which has been aligned or stapled after being aligned, by the sheet clamp member  412 .  
      Then, thereafter, the sheet bundle discharging member  413  is adapted so as, when arriving at a fore end portion of the treatment tray  410  as the sheet discharging position indicated by a solid line in  FIG. 8 , to release the holding of the sheet bundle SA with the sheet clamp member  412  on a stack tray  421  to discharge and stack the sheet bundle SA onto the stack tray  421 . Incidentally, a holding member  421 A shown in  FIG. 2  is adapted to hold the sheet bundle SA thus discharged and stacked onto the stack tray  421 .  
      Here, the sheet bundle discharging member  413  has motive power transmitted thereto by a sheet bundle discharging motor  430  through a rack and a pinion as shown in  FIG. 5 . Thereby, the sheet bundle discharging member  413  can be reciprocally moved between a position for discharging the sheet onto the stack tray  421  and its home position near the sheet trailing edge stopper  411 . The sheet bundle discharging member  413  is ordinarily fixed in the home position by the excitation of the sheet bundle discharging motor  430 .  
      In  FIG. 5 , a clamp solenoid  434  pivotally moves the sheet clamp member  412 . The clamp solenoid  434 , when the offset roller  407  stops rotating after it has conveyed the sheet, and when the offset roller  407  is moved in the width direction, is adapted to be turned on to thereby upwardly pivotally move the sheet clamp member  412  through a lever  434   a  and a releasing lever portion  412   a  provided on the sheet clamp member  412 .  
       FIG. 9  is a block diagram showing the construction of the controlling portion of the sheet processing apparatus  400  of such a construction.  FIG. 9  shows a CPU  100  as an example of control device in this embodiment. The CPU  100  has a ROM  110  therein. The ROM  110  has stored therein a program, etc. corresponding to a control procedure shown in  FIGS. 10 and 11  which will be described later. The CPU  100  is adapted to read out and execute this program and control each portion.  
      Also, the CPU  100  contains therein a RAM  121  in which data for work and input data are stored, and the CPU  100  is adapted to perform the control with reference to the data contained in the RAM  121  on the basis of the aforementioned program. Further, sensors such as an entrance sensor  403  exemplified as a sheet detecting device and a sheet bundle discharge sensor  415  and a retention jam timer T for detecting a sheet retention within the sheet processing apparatus are connected to the input port of the CPU  100 .  
      Further, motors and solenoids such as the conveying motor  431 , the offset motor  432 , the sheet bundle discharging motor  430 , the pickup solenoid  433 , the clamp solenoid  434  are connected to output ports of the CPU  100 . The CPU  100  is adapted to control the loads of the various motors and solenoids connected to the output ports in accordance with the aforementioned program based on the states of the sensors.  
      Also, the CPU  100  is provided with a serial interface portion (I/O)  130 , and is adapted to effect the giving and receiving of control data with (the controlling portion of) the image forming apparatus main body  500 , and also perform the control of each portion on the basis of control data sent from (the controlling portion of) the main body  500  of the image forming apparatus through the serial interface portion (I/O)  130 .  
      The main body  500  of the image forming apparatus recognizes the size of the sheet discharged from the sheet discharging portion  208 . Owing to this, the controlling portion of the sheet processing apparatus  400 , which is constituted of a micro computer system, can recognize the size of the sheet inserted into the treatment tray  410  by means of serial communication with the controlling portion of the main body  500  of the image forming apparatus.  
      In the present embodiment, the sheet bundle stacked on the stack tray  421  constitutes a portion of the treatment tray  410  and therefore, when the discharge of the sheet bundle SA is done from the treatment tray  410 , the stack tray  421  is adapted to be lowered by a stack tray lifting/lowering motor  450  (see  FIG. 9 ) until the uppermost surface of the stacked sheet bundle is substantially flush with the treatment tray  410 .  
      Next, the residual sheet processing operation of the sheet processing apparatus  400  and the main body  500  of the image forming apparatus at turning on the power will be described with reference to the flow charts shown in  FIGS. 10 and 11 .  
      When the main body  500  of the image forming apparatus detects a sheet remaining in the apparatus (in the path) with a residual sheet detecting device (not shown) at turning on the power (“Y” in S 1000 ), the main body  500  of the image forming apparatus discharges the sheet to the sheet processing apparatus  400  (S 1001 ).  
      The CPU  100  of the sheet processing apparatus  400  (see  FIG. 9 ) detects the sheet discharged from the main body  500  of the image forming apparatus by the entrance sensor  403  of the sheet processing apparatus  400 . When the entrance sensor  403  turns on (“Y” in S 1010 ), the CPU  100  activates the pickup solenoid  433 . Owing to this, the offset rollers  407  supported by the offset roller arm  406  is pulled up and raised (S 1020 ).  
      Next, the conveying motor  431  is turned on to drive the conveying rollers  405  and the offset rollers  407  provided on the sheet discharging path to rotate in the same sheet conveying direction as the discharge direction from the main body  500  of the image forming apparatus (S 1030 ). Thereafter, the sheet arrives at the conveying roller  405  and there is brought about a state in which motive power is transmitted from the conveying roller  405  to the sheet, and the sheet is separated from the sheet discharging portion  208  (see  FIG. 1 ) of the image forming apparatus main body  500 , whereupon the delivery of the sheet is completed.  
      Next, the retention jam timer T is set to detect retained sheet (jammed sheet) in the sheet processing apparatus (S 1040 ). Next, the CPU  100  conveys the sheet to the treatment tray  410  by  80  mm in this embodiment by the conveying roller  405  (S 1050 ) and yet, turns the pickup solenoid  433  off before the sheet completely leaves the conveying roller  405 , and makes the offset roller  407  lower onto the sheet with the aid of the gravitational force of the offset roller  407  (S 1060 ).  
      Thereafter, the CPU  100  waits until the trailing edge of the sheet passes the entrance sensor  403  of the sheet processing apparatus to turn off the entrance sensor  403  (S 1070 ). Then, when the entrance sensor  403  turns off (“Y” in S 1070 ), the CPU  100  judges that the sheet is not jammed, and resets the retention jam timer T (S 1090 ).  
      Also, the offset rollers  407  are caused to rotate for a predetermined period of time from the turning off of the entrance sensor  403  to convey the sheet S so that the trailing edge of the sheet moves to a predetermined position downstream of the sheet trailing edge stopper  411 . Then, when the sheet S is conveyed to such a position, the CPU  100  stops the rotation of the conveying motor  431  to thereby stop the conveying rollers  405  and the offset rollers  407  (S 1100 ).  
      In addition, when the entrance sensor  403  of the sheet processing apparatus does not turn off (N in S 1070 ) even if the retention jam timer T has timed up (Y in S 1150 ), the CPU  100  judges that a jam has occurred and enters into a jam mode (S 1160 ).  
      Next, the CPU  100  turns the clamp solenoid  434  on at a point of time whereat the rotation of the offset roller  407  has been stopped (S 1100 ), and as shown in  FIG. 6B , opens the sheet clamp member  412  installed in the home position near the trailing edge stopper  411 . Thereafter, the CPU  100  rotates the conveying motor  431  in a direction reverse to the conveying direction, and pulls back the sheet S by the offset roller  407  (S 1120 ), and causes the trailing edge of the sheet to abut against the trailing edge stopper  411 .  
      The amount of rotation of the offset roller  407  when the trailing edge of the sheet is abutted against the sheet trailing edge stopper  411  is set, with the skew feed of the sheet S occurring when it is conveyed from the main body  500  of the image forming apparatus taken into account. Therefore, in this embodiment, the rotation amount of the offset rollers  407  is prescribed to a rotation amount, in which the sheet can be conveyed somewhat more than the distance from a switch back point at which the conveyance of the sheet S is stopped to the sheet trailing edge stopper  411 .  
      Next, the offset rollers are raised (S 1130 ) and the sheet bundle discharging member  413  is caused to proceed in a direction of the stack tray  421  by the sheet bundle discharging motor  430  in a state that a sheet S is clamped (held) by the sheet clamp member  412  as shown in  FIG. 8 . Then, when the sheet bundle discharging member  413  arrives at the fore end portion of the treatment tray  410 , the hold of the sheet by the sheet clamp member  412  is released on the stack tray  421  so that the sheet may be discharged onto the stack tray  421  (S 1140 ).  
      In addition, after discharging the sheet as described above, the sheet bundle discharging member  413  is returned to its home position. Also, the pickup solenoid  433  is turned off to lower the offset rollers  407 , and thus the series of the processing is terminated.  
      As described above, the CPU  100  is designed so as, when a residual sheet is conveyed from the main body  500  of the image forming apparatus at turning on the power, to cause the sheet bundle discharging member  413  to move to the position, in which the sheet is discharged onto the stack tray  421 , while holding the residual sheet after the trailing edge of the residual sheet is aligned. Owing to this, even when the sheet size is unknown, the alignment of the residual sheet on the stack tray can be secured.  
      In this embodiment, although the CPU  100  reads out the program written on the RAM (or ROM) shown in the flow chart in  FIGS. 10 and 11  to control the operation, a similar effect will also be obtained if design is made such that the processing in the control program is carried out by hardware.  
      Also, in the above description, the case where the CPU  100  of the sheet processing apparatus  400  controls the above process has been described. However, design may be made such that the controlling portion of the main body  500  of the image forming apparatus performs the above control.  
      As described in this embodiment, when a residual sheet is conveyed from the main body of the image forming apparatus at turning on the power, the discharging member is moved to the sheet discharging position, in which the sheet is discharged onto the second sheet stacking portion, while holding the residual sheet by the holding member after aligning the trailing edge of the residual sheet. Thereby, the stackability of the sheet when the residual sheet is discharged can be secured.  
      While the present invention has been described with reference to the exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.  
      This application claims the benefits of Japanese Patent Application No. 2005-328111, filed Nov. 11, 2005, which is hereby incorporated by reference herein in its entirety.