Patent Publication Number: US-8123215-B2

Title: Sheet aligning apparatus and image forming system

Description:
This application is based on Japanese Patent Application No. 2008-126829 filed on May 14, 2008 in Japanese Patent Office, the entire content of which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a sheet aligning apparatus and an image forming system. Especially, the present invention relates to a sheet aligning apparatus which makes it possible to perform a sheet post processing efficiently and an image forming system equipped with the sheet aligning apparatus. 
     Conventionally, as an image forming system, a well known system is equipped with an image forming apparatus, such as a printer, a copying machine, and a composite machine, and a post processing apparatus which performs a post processing, such as a punching process, a folding process, a binding process, and so forth for to sheets on which images have been formed by the image forming apparatus. 
     A post processing section as a structural section of an image forming system is generally an apparatus which performs a shifting process, a punching process, a binding process, a folding process, a pasting bookbinding process, etc. for sheets on which images have been formed. 
     Moreover, for such a punching process section, a binding process section, a folding process section, and a pasting bookbinding process section, an aligning process section for aligning sheets as a pretreatment section of those processes is provided. 
     Generally, this aligning process section is provided in a post processing section, has a structure which comprises an inclined intermediate stacker and a movable regulating member provided in the both sides or one side of the intermediate stacker, and conducts an aligning process for sheets on a conveyance path to convey sheets to a binding process section or a folding process section. Namely, the aligning process section drops and slides sheets into the inclined intermediate stacker to align sheets in the conveying direction. In the stage where the preset number of sheets has been accumulated in the intermediate stacker, the aligning process section stops feeding sheets to the intermediate stacker, reciprocates a movable regulating member, and aligns sheets in the widthwise direction of the conveyance path. Thereafter, a post processing, such as a punching process, a binding process, a folding process, and a pasting bookbinding process, is performed for the aligned sheets. 
     Furthermore, in conventional post processing apparatuses, there is a post processing apparatus in which a sheet reversing conveying section called an intermediate conveyance unit and a sheet width regulating member to align sheets widthwise are provided before post processing. However, there is no post processing apparatus equipped with a sheet aligning section to align sheets in the sheet conveying direction in the sheet reversing conveying section. The conventional post processing apparatuses conduct sheet aligning just before performing post processing, such as a punching process, a binding process, and a folding process by regulating the leading end or back end of sheets in respective post process. 
     Therefore, since it is necessary to take time to align sheets in each post process, there is a problem that a sheet processing speed becomes low. 
     Moreover, conventional aligning process sections need to stop conveying a succeeding sheet during conducting post processing for preceding sheets. Therefore, since the sheet processing speed becomes low more, the conventional aligning process sections are not suited for the high speed performance of an image forming apparatus. As a result, there is a problem that the high speed performance of an image forming apparatus is not fully exhibited. 
     Furthermore, when performing an aligning process, since conveyance stop control is executed, the control method becomes complicated, and stability tends to be failed. Therefore, there is further a problem that a conveyance trouble such as a jam tends to occur easily. 
     In order to solve these problems, for example, Japanese Patent Unexamined Publication No. 2007-137536 discloses a technique to provide a sheet aligning apparatus in an intermediate conveyance unit so that a plurality of sheets are conveyed simultaneously and an aligning process for succeeding sheets can be performed at high speed even if preceding sheets are subjected to a post processing. 
     According to the technique disclosed by the above publication, a sheet storage section to store a plurality of inversed sheets is provided between an image forming apparatus and a post processing apparatus, the sheet storage section receives sheets by a stop member capable of shifting upward and downward, and conducts sorting and aligning succeeding sheets in the conveying direction by shifting the stop member. 
       FIG. 16  is a front side cross sectional view of an intermediate conveyance unit B which has the sheet storage section equipped with the sheet aligning device disclosed by the above publication. 
     Hereafter, the structure and operations of the sheet aligning apparatus by the use of the above intermediate conveyance unit B are explained as an conventional example with reference to  FIG. 16 . 
     In  FIG. 16 , the intermediate conveyance unit B is provided at the downstream side of an image forming apparatus main body A in the sheet conveying direction, and a post processing apparatus FS is arranged further at the downstream side of the intermediate conveyance unit B. 
     A sheet conveyance section of the intermediate conveyance unit B is constituted by a sheet conveying-in section (first conveying section)  11 , a sheet storage section (second conveying section)  12 , a sheet conveying-out section (third conveying section)  13 , and a sheet reversing section (fourth conveying section)  14 . 
     The sheet conveying-in section  11  is equipped with a sheet conveying-in conveyance path r 11  which comprises conveying rollers R 1  and R 2  and a guide plate  111 . In the sheet conveying-in section  11 , sheets S discharged from a discharging section  5 E of the image forming apparatus main body A are conveyed sequentially. 
     The sheet storage section  12  is equipped with two guide plates  121 , a widthwise aligning section  122 , a stop member  123 , a lengthwise aligning member  124 , a conveying-in drive roller R 3 , a conveying-out drive roller R 4 , and a sheet storage conveyance path r 12 . 
     The two guide plates  121  are arranged in parallel, and form the sheet storage conveyance path r 12  therebetween. 
     The sheet storage conveyance path r 12  is a conveying path for conveying in or conveying out sheets S for the sheet storage section  12 . 
     Plural sheets S conveyed from the sheet conveying-in section  11  into the sheet storage section  12  are arranged on the stacked condition and stored in the sheet storage section  12 . Then, the plural sheets S are aligned in the sheet conveying direction between the stop member  123  and the lengthwise aligning member  124 , further aligned in the sheet width direction by the widthwise aligning member  122 , and thereafter discharged upward. 
     The stop member  123  being stopping and waiting at an initial stop position P 0  is shifted upward by a motor (not illustrated in the drawing) along the sheet storage conveyance path r 12 , and stopped at the first stop position P 1  or the second stop position P 2 . 
     Namely, a preceding sheet S 1  is conveyed in the sheet conveying-in direction from the sheet conveying-in section  11  into the sheet storage section  12 , and the leading end of a preceding sheet S 1  in the sheet conveying-in direction comes in contact with a stopping surface  123 A of the stop member  123 . Thereafter, the stop member  123  is shifted upward in the sheet conveying-out direction by a stop member shifting section (the above motor) so that the stop member  123  conveys the preceding sheet S 1  inversely in the sheet conveying-out direction. Then, the back end of the preceding sheet becomes the inversed leading end of the preceding sheet in the sheet conveying-out direction by the inversely conveying, and when the inversed leading end (the back end) of the preceding sheet arrives at a middle point between the conveying-in drive roller R 3  and the conveying-out drive roller R 4 , the stop member  123  is stopped at the first stop position P 1 . Hereafter, in order to make the word “the leading end in the conveying-out direction” distinguishable from the word “the leading end in the conveying-in direction”, “the leading end in the conveying-out direction” is expressed as “the inversed leading end in the conveying-out direction” or “the inversed leading end”. 
     Here, the first stop position P 1  is a position to stop the stop member when the inversed leading end of the preceding sheet has passed over the lower end position of a conveyance path switching member G 1  and reached a region before a nip section of a conveying-out drive roller R 4 , whereby the interruption of a succeeding sheet can be avoided. 
     After the stop member  123  conveying the preceding sheet S 1  has stopped at the first stop position P 1 , a succeeding sheet S 2  is conveyed in towards the sheet storage section  12  by the rotation of the conveying-in drive roller R 3 . Since the inversed leading end of the preceding sheet S 1  is positioned upward from the leading end of the succeeding sheet S 2  by shifting the stop member  123  to the first stop position P 1 , the inversed leading end of the preceding sheet S 1  does not interfere with the leading end of the succeeding sheet S 2 . 
     Then, with the conveying-in of the succeeding sheet S 2  into the sheet storage section  12 , the stop member  123  is driven by the stop member shifting section, and returns to the initial stop position P 0 , and the preceding sheet S 1  and the succeeding sheet are stored on the stacked condition in the sheet storage section  12 . 
     When the predetermined number of sheets S are stored in the sheet storage section  12 , the stop member  123  is driven again by the stop member shifting section so as to be shifted upward, and is stopped at the second stop position P 2  located at the downstream side of the first stop position P 1  in the sheet conveying-out direction. 
     Here, the second stop position P 2  is a position to stop the stop member  124  when the reversed leading end of the plural sheets S shifted together with the stop member  123  arrives at a position where the reversed leading end of the plural sheets S come in contact with the lengthwise aligning member  124  in such a way that the plural sheets S are aligned in the sheet conveying direction. 
     The conveyance path switching member G 1  is arranged at the upper portion of the sheet storage section  12  and switches a conveying-in path to convey a sheet S into the sheet storage section  12  and a conveying-out path to covey a sheet S from the sheet storage section  12 . 
     The plural sheets S aligned by the lengthwise aligning member  124  are pinched between the conveying-out drive roller R 4  and the conveying-out follower roller R 11  by the switch operation of the conveyance path switching member G 1 , and are conveyed to the sheet conveying-out section  13 . 
     The sheet conveying-out section  13  is equipped with a sheet conveying path r 13  including an intermediate conveying roller R 5 , a sheet ejecting roller R 6 , and a guide plate  131 . In the sheet conveying-out section  13 , the plural sheets S stored in the sheet storage section  12  are conveyed out inversely on the stacked condition, and are conveyed into a succeeding sheet post processing apparatus FS. 
     Further, the sheet inversing section  14  is equipped with a sheet conveying path r 14  including conveying rollers R 7  and R 8 , and a guide plate  141 . In the sheet inversing section  14 , the plural sheets S stored in the sheet storage section  12  pass over an upper sheet conveying path r 15 , are re-inversed by a switchback operation on a sheet conveying path r 14 , pass over a lower sheet conveying path r 16 , are discharged from the lower sheet conveying path r 16 , and are sent into the succeeding sheet post processing apparatus FS. 
     A conveyance path switching member G 2  arranged at the sheet conveying-out section  13  switches a path either one of the sheet conveying path r 13  to convey the plural sheets S conveyed from the sheet storage section  12  to the conveying-out drive roller R 4  along the guide plate  131  and the sheet conveying path r 15  to convey the plural sheet S to the sheet inversing section  14 . 
     A conveyance path switching member G 3  arranged at the lower part of the sheet inversing section  14  switches a path either one of the sheet conveying path r 15  being opened by the conveyance path switching member G 2  and the sheet conveying path r 16  to discharge the plural sheets S from the sheet inversing section  14 . The conveyance path switching members G 1 , G 2 , and G 3  are connected with solenoids respectively and are driven by them. 
     According to the intermediate conveyance unit B described in the above publication, even when preceding sheets are subjected to a post processing, it is possible to stack plural succeeding sheets without making them to interfere with each other and to conduct a lengthwise aligning process at high speed, without stopping conveyance of the plural succeeding sheets. 
     Moreover, since the stop member  123  constituting the sheet storage section  12  to store the preceding sheets S 1  is shifted to the first stop position P 1  before the leading end of the succeeding sheet S 2  advances into the sheet storage conveyance path r 12 , the leading end of the succeeding sheet S 2  does not interfere with the inversed leading end of the preceding sheet S 1 , and the succeeding sheet S 2  is stacked properly on the preceding sheet S 1 . 
     However, in the intermediate conveyance unit B described in the above publication, since the shifting of the stop member  123  from the initial stop position P 0  to the first stop position P 1  is performed at high speed, even if the stop member  123  is stopped at the first stop position P 1 , the sheet S 1  may proceed excessively according to the inertia of the sheet S 1 . That is, when the stop member  123  is stopped at the first stop position P 1 , if the leading end (inversed back end) of the sheet S 1  is in close contact with the contact surface of the stop member  123 , the back end (the inversed leading end) may locate between the conveying-in drive roller R 3  and the conveying-out drive roller R 4 . However, the leading end separates away from the contact surface of the stop member  123  according to the inertia of the sheet S 1 . As a result, the inversed leading end of the sheet S 1  is pinched between the conveying-out follower roller R 11  of the conveyance path switching member G 1  and the conveying-out drive roller R 4 , and there is fear to cause a problem that the sheet S 1  is left on the pinched condition even if the stop member  123  is shifted downward to the initial position P 0 . An occurrence of the phenomenon that the sheet to be shifted downward does not come down without following the stop member  123  being shifted causes problems, such as a conveyance failure of a sheet, and an aligning failure, and further causes a big problem. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to solve the above problems and to provide a sheet aligning apparatus capable of aligning sheets properly and conveying the sheets stably at high speed at the time of performing a post processing and an image forming system equipped with the sheet aligning apparatus. 
     In order to attain the above object, a sheet aligning apparatus reflecting on aspect of the present invention, comprises: 
     (1) a sheet storing section having an open end portion through which a sheet is conveyed in or out; 
     (2) a conveying-in section having a conveying-in path to covey a sheet into the open end portion of the sheet storing section; 
     (3) a conveying-out section having a conveying-out path to covey out a sheet from the open end portion of the sheet storing section, wherein the conveying-in path and the conveying-out form a meeting point at the open end portion; 
     (4) a stop member arranged in the sheet storing section so as to oppose the open end portion; 
     (5) a shifting section to shift the stop member from an initial position to a first position, wherein when the stop member is positioned at the initial position, the stop member comes in contact with a leading end of a preceding sheet conveyed into the sheet storing section through the open end portion, and when the shifting section shifts the stop member from the initial position to the first position, the preceding sheet is shifted inversely together with the stop member and a back end of the preceding sheet proceeds as the inversed leading end from the meeting point to the conveying-out path so that a succeeding sheet is allowed to be conveyed from the conveying-in path into the open end portion; 
     (6) a shift regulating section to regulate the shift of the preceding sheet when the shifting section shifts the stop member from the initial position to the first position, so that the back end of the preceding sheet is prevented from proceeding more than a predetermined distance due to the inertia of the shift. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  is an entire structural view of an image forming system according to the present invention which comprises an image forming apparatus main body A, an automatic document sheet feeding apparatus DF, a large amount sheet feeding apparatus LT, an intermediate conveyance unit B, and a sheet post processing apparatus FS. 
         FIG. 2  is a schematic structural view for explaining the structure and operations of a driving section of the first embodiment of a sheet aligning apparatus B 1  according to the present invention. 
         FIG. 3  is a graph for explaining a control method for a shifting speed of a stop member  123  in the first embodiment according to a sheet aligning apparatus B 1  of the present invention. 
         FIG. 4  is a cross sectional view showing a driving section of a widthwise aligning section  122 . 
         FIGS. 5(   a ) and  5 ( b ) each is a cross sectional view showing a sheet conveyance process in the first embodiment according to a sheet aligning apparatus B 1  of the present invention. 
         FIGS. 6(   a ) and  6 ( b ) each is a cross sectional view showing a sheet conveyance process in the first embodiment according to a sheet aligning apparatus D 1  of the present invention. 
         FIGS. 7(   a ) and  7 ( b ) each is a cross sectional view showing a sheet conveyance process in the first embodiment according to a sheet aligning apparatus B 1  of the present invention. 
         FIGS. 8(   a ) and  8 ( b ) each is a cross sectional view showing a sheet conveyance process in the first embodiment according to a sheet aligning apparatus B 1  of the present invention. 
         FIG. 9  is a schematic structural view for explaining the structure and operations of a driving section of the second embodiment according to a sheet aligning apparatus B 1  of the present invention. 
         FIG. 10  is a schematic structural view for explaining the structure and operations of a driving section of the third embodiment according to a sheet aligning apparatus B 1  of the present invention. 
         FIG. 11  is a control block diagram showing a command system at the time of controlling each part by a control section  9 B in the first to third embodiment of the sheet aligning apparatus B 1  according to the present invention. 
         FIG. 12  is a timing chart about the second and third embodiments in the sheet aligning apparatus B 1  according to the present invention. 
         FIG. 13  is a flowchart for explaining the procedures of operations of the first embodiment of in the sheet aligning apparatus B 1  to according to the present invention. 
         FIG. 14  is a flowchart for explaining the procedures of operations of the second embodiment of in the sheet aligning apparatus B 1  to according to the present invention. 
         FIG. 15  is a flowchart for explaining the procedures of operations of the third embodiment of in the sheet aligning apparatus B 1  to according to the present invention. 
         FIG. 16  is a front side cross sectional view of an intermediate conveyance unit B disclosed by Patent document 1. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Although the present invention is explained based on the embodiments indicated in the drawing, the present invention is not limited to these embodiments. 
     [Image Forming System] 
       FIG. 1  is an entire configuration view of an image forming system according to the present invention which comprises an image forming apparatus main body A, an automatic document sheet feeding apparatus DF, a large amount sheet feeding apparatus LT, an intermediate conveying-out unit B, and a sheet post processing apparatus FS. 
     [Image Forming Apparatus Main Body A] 
     The image forming apparatus main body A shown in the drawing is equipped with an image reading section  1 , an image processing section  2 , an image writing section  3 , an image forming section  4 , a feed sheet conveying section  5 , and a fixing device  6 . 
     An image forming section  4  is constituted by a photoreceptor drum  4 A, a charging section  4 B, a developing section  4 C, a transferring section  4 D, a separating section  4 E, and a cleaning section  4 F. 
     The feed sheet conveying section  5  is equipped with a sheet cassette  5 A, a first sheet feeding section  5 B, a second sheet feeding section  5 C, a conveying section  5 D, a discharging section  5 E, and an automatic double-sided copy sheet feeding section (ADU)  5 F. 
     An operation display section  8  including an input section and a display section is arranged at the upper front side of the image forming apparatus main body A. The automatic document sheet feeding apparatus DF is mounted on the upper part of the image forming device body A. The intermediate conveyance unit B is linked with the discharging section  5 E side of the left side plane (illustrated in the drawing) of the image forming apparatus main body A, and the sheet post processing apparatus FS is linked with the further left side. 
     Images on one side or both sides of document sheets placed on a document stand of the automatic document sheet feeding apparatus DF are read by an optical system of the image reading section  1 . Analog signals having been subjected to an photoelectric conversion are further subjected to an analog processing in the image processing section  2 , an A/D conversion, a shading correction, an image compression process, and the like, thereafter, are sent to the image writing section  3 . 
     In the image writing section  3 , light rays outputted from a semiconductor laser is irradiated onto a photoreceptor drum  4 A of the image forming section  4 , thereby forming a latent image. In the image forming section  4 , an electrically-charging, exposure, development, transfer, separation, cleaning, etc. are performed. 
     An image is transferred by a transferring section  4 D onto a sheet S fed by the first sheet feeding section  5 B. The sheet S carrying the image is fixed by the fixing device  6 , and is sent into an intermediate conveyance unit B from the discharging section  5 E. Alternately, the sheet S on the one side of which an image has been formed is sent into the automatic double-sided copy sheet feeding section  5 F so as to form an image on another side of the sheet in the image forming section  4 . After the double-sided image processing, the sheet S is again discharged by the discharging section  5 E, and is sent into the intermediate conveyance unit B. 
     A communication section of the control section  9 A arranged in the image forming apparatus main body A and a communication section of the control section  9 B arranged in intermediate conveyance unit B are connected via a communication line  9 C, and transmits and receives an input signal and a control signal. 
     Moreover, the control section  9 B controls the operations of each part in intermediate conveyance unit B through transmission and receipt of signals with the control section DA. 
     [Large Amount Sheet Feeding Apparatus LT] 
     The large amount sheet feeding apparatus LT is constituted by a sheet stack section  7 A and a first sheet feeding section  7 B, and feeds out a large amount of sheets S continuously into the image forming apparatus main body A. 
     [Intermediate-Conveyance-Unit B] 
     The structure and operations of the sheet aligning apparatus B 1  constituting a part of the intermediate conveyance unit B according to the present invention are similar to those of the conventional example explained with reference to  FIG. 16 , and a member having the same function is applied with the same reference symbol. Therefore, the explanation for such a member is omitted, and different structures and different operations are explained hereafter. 
     The sheet aligning apparatus B 1  according to the present invention shall is an apparatus with a structure adding a conveyance path switching member G 1  to a sheet storage section  12 . 
     Hereafter, in the sheet aligning apparatus B 1  according to the present invention, the structures and operations of the first, second and third embodiments are explained with reference to the drawing. 
       FIG. 2  is a schematic structural diagram for explaining the structures and operations of a driving section of the first embodiment in the sheet aligning apparatus B 1  according to the present invention. 
     In  FIG. 2 , the conveyance path switching member G 1  which supports a conveying-in follower roller R 10  as a sheet conveying-in section and a conveying-out follower roller R 11  is driven and rocked by a solenoid SOL 1 . The conveying-in drive roller R 3  is driven by a solenoid SOL 2  so as to open and close the sheet conveying-in conveyance path r 11 . A lengthwise aligning member  124  for aligning sheets in the sheet conveying direction is driven and rocked by a solenoid SOL 3 . 
     A motor M 1  as a conveying-in roller driving section drives and rotates a conveying roller R 2 , and rotates a conveying-in drive roller R 3  through a belt. 
     A motor M 2  as a conveying-out roller driving section drives and rotates a conveying-out drive roller R 4  as a sheet conveying-out section. 
     The stop member  123  is shifted by a stop member shifting section, and the stop member shifting section is constituted by a motor M 3  with a changeable speed, a belt  125 , a guide bar  126  and so forth. The stop member  123  is attached to a belt  125  being rotated by a motor M 3 , is guided by a guide bar  126 , and shifts up and down between an initial stop position P 0  and a first stop position P 1  or between the initial stop position P 0  and a second stop position P 2 . 
     A sheet shifting section YS as a sheet storage section according to the present invention is constituted by the stop member  123  capable of shifting and a sheet storage conveyance path r 12  formed by two guide plates  121 , and shifts sheets along a sheet storage conveyance path r 12 . 
     Here, since sheets S are inversely conveyed in the sheet shifting section YS according to the present invention, the sheet conveying-out direction is made inverse to the sheet conveying-in direction. Therefore, the leading end of a sheet in the sheet conveying-in direction is the same portion of the back end (the inversed back end) of the sheet in the sheet conveying-out direction. 
     Further, two rollers of the conveying-in drive roller R 3  and the conveying-in follower roller R 10  which come in pressure contact with each other in order to convey a sheet S from the sheet conveying-in conveyance path r 11  into the sheet shifting section YS are named generically as a sheet conveying-in roller pair. The sheet conveying-in roller pair is arranged on a sheet conveying-in conveyance path r 11  located at an upstream side from a juncture C in the sheet conveying-in direction. 
     Furthermore, two rollers of the conveying-out drive roller R 4  and the conveying-out follower roller R 11  which come in pressure contact with each other in order to convey out a sheet S from the sheet shifting section YS into the next process are named generically as a sheet conveying-out roller pair. The sheet conveying-out roller pair is arranged on a sheet storage conveyance path r 12  located at a downstream side from a juncture C in the sheet conveying-out direction. 
     The first embodiment according to the sheet aligning apparatus B 1  of the present invention differs from the conventional example explained with reference o  FIG. 16  in the point that a shifting speed Vb 1  of the stop member  123  from the initial stop position P 0  to the first stop position P 1  is controlled by the control section  9 B. That is, a motor capable of changing a speed, such as a stepping motor, is used as the motor M 3  as a stop member shifting section, and a shifting speed at the time of shifting the stop member  123  from the initial stop position P 0  to the first stop position P 1  is changed in order to make the inertia moment of the stop member  123  small. 
     Hereafter, the control method of the speed control in the first embodiment according to the sheet aligning apparatus B 1  of the present invention is explained with reference to  FIG. 3 . 
       FIG. 3  shows a graph for explaining the control method of the shifting speed of the stop member  123  in the first embodiment according to the sheet aligning apparatus B 1  of the present invention. 
     In  FIG. 3 , an axis of ordinate shows change of the shifting speed at the time of shifting the stop member  123  from the initial stop position P 0  to the first stop position P 1 , and an axis of abscissa shows necessary time at the time of shifting the stop member  123  from the initial stop position P 0  to the first stop position P 1 . The dotted line a is a line which shows the speed change in the conventional example in which the shifting speed Va 1  of the stop member  123  is made an usual sheet conveying speed, and the solid line b is a line which shows the speed change when the shifting speed Vb 1  of the stop member  123  is controlled by the stop member shifting section according to the present invention. The sign “Ta” shows the speed reducing time in the conventional example, and the sign “Tb” shows the speed reducing time in the present invention. 
     Example 
     The present inventor conducted the comparative experiment between Example 1 and Comparative example 1 with reference to the influence of the inertia provided to a sheet S 1  by the shifting speed at the time of shifting the stop member  123  from the initial stop position P 0  to the first stop position P 1 . 
     Comparative Example 1 
     In Comparative example 1, the shifting speed Va 1  of the stop member  123  was made to 600 mm/s of the usual sheet conveying speed, and the speed reducing time Ta was set to 15 m. 
     Example 1 
     In Example 1, in order to reduce the inertia moment provided to a sheet, the shifting speed Vb 1  of the stop member  123  was made to 300 mm/s slower than the usual sheet conveying speed, and the speed reducing time Ta was set to 9 ms. 
     The result of the comparative experiment is shown in Table 1. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Shifting 
                 Speed 
                   
               
               
                   
                 speed 
                 reducing time 
                 Result 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Comparative 
                 600 mm/s 
                 15 ms 
                 Yes 
               
               
                   
                 example 
               
               
                   
                 Example 
                 300 mm/s 
                  9 ms 
                 No 
               
               
                   
                   
               
               
                   
                 Yes: A conveyance failure was occurred 
               
               
                   
                 No: A conveyance failure was not occurred 
               
            
           
         
       
     
     In Comparative example 1, at the time of shifting the stop member  123  to the first stop position P 1 , the position of the inversed leading end of a sheet S 1  in the sheet conveying-out direction passed over a predetermined region SR due to the inertia of the sheet S 1 , and reached the downstream side in the sheet conveying direction from the position of the nip section between the conveying-out drive roller R 4  and the conveying-out follower roller R 11 . Thereafter, when the conveying-out follower roller R 11  was returned to a position to come in contact with the conveying-out drive roller R 4  to form a nip section by the switching operation of the conveyance path switching member G 1 , the inversed leading end of the sheet S 1  was pinched by the nip section, and a conveyance failure occurred. 
     In Example 1 in which the shifting speed Vb 1  of the stop member  123  was controlled, at the time of shifting the stop member  123  to the first stop position P 1 , the position the inversed leading end of a sheet S 1  in the sheet conveying-out direction was located at a position in predetermined region SR. As a result, by the switching operation of the conveyance path switching member G 1 , the inversed leading end of the sheet S 1  is not pinched by the above-mentioned nip section, and conveyance failure did not occur. 
     Here, in this experiment, on the condition that the stop member  123  was stopped at the first stop position P 1  and the inversed back end of a sheet S 1  was in contact with the stopping surface  123 A of the stop member  123 , the distance from the inversed leading end of the sheet S 1  in the sheet conveying-out direction to the nip section was set to 12 mm. 
     Although the shifting speed Vb 1  of the stop member  123  was made to 300 mm/s in Example 1, the shifting speed Vb 1  is not limited to this speed. As far as a speed can refrain the inertia of a sheet, the speed can be employed as the shifting speed Vb 1 . Moreover, the speed is not necessary to be changed linearly, and can be changed to increase or decrease in a curve shape smoothly. 
     By employing the speed control method of the first embodiment speed according to the sheet aligning apparatus B 1  of the present invention, the inertia moment due to the shifting of the stop member  123  can be reduced. As a result, it is possible to prevent a sheet from being moved across a predetermined region and to avoid resultant conveyance failure. 
       FIG. 4  is a cross sectional view showing a driving section of a widthwise aligning section  122 . 
     The widthwise aligning section  122  is constituted by widthwise aligning plates  122 A of a right and left pair, a motor M 4 , a belt  127 , pins  128 A and  128 B, etc. 
     The widthwise aligning plates  122 A of a right and left pair are engaged with pins  128 A and  128 B attached to a belt  127  being rotated by a motor M 4 , and are adapted to be moved with the pins in the sheet width direction so as to perform the widthwise aligning of sheets S. 
       FIGS. 5 to 8  are cross sectional views showing respectively a sheet conveyance process in the first embodiment according to the sheet aligning apparatus B 1  of the present invention. Hereafter, the sheet conveyance process in the first embodiment of the sheet aligning apparatus B 1  will be explained with reference to  FIGS. 5 to 8 .
     (1) In  FIG. 5(   a ), the conveying-in follower roller R 10  supported rotatably by the lower end of the conveyance path switching member G 1  is brought in contact with the conveying-in drive roller R 3  rotating with a driving force, and is driven with a following rotation. The first preceding sheet S 1  pinched and conveyed by the conveying roller R 2  rotating with a driving force is conveyed along the guide plate  111  on the sheet conveying-in conveyance path r 11 , then, is pinched and conveyed by the conveying-in drive roller R 3 , and advances towards the sheet shifting section YS of the sheet storage section  12 .   (2) In  FIG. 5(   b ), the leading end of the first preceding sheet S 1  conveyed into the sheet shifting section YS comes in contact with the stopping surface  123 A of the stop member  123  being waiting at the initial stop position P 0 , and the first preceding sheet S 1  stops there.   (3) In  FIG. 6(   a ), the conveyance path switching member G 1  is actuated to separate the conveying-out follower roller R 11  supported rotatably at an intermediate position of the conveyance path switching member G 1  away from the conveying-out drive roller R 4 . At this time, the conveying-in drive roller R 3  is pushed by the conveyance follower roller R 11  so as to be rocked around the conveying roller R 2  as the center of rocking, and is retracted from the sheet conveying-in conveyance path r 11  to the outside of the path. Then, the stop member  123  is shifted to the first stop position P 1  located upward by only the predetermined distance L 1  (for example, 30 mm) from the initial stop position P 0  by a motor M 3  as a stop member shifting section, whereby the inversed leading end of the first preceding sheet S 1  reaches to the predetermined region SR, and stops there.   

     Here, the predetermined region SR in this embodiment section is a region between a position at the downstream side in the sheet conveying-out direction from the junction of the sheet conveying-in conveyance path r 11  and the sheet storage conveyance path r 12  and a position of the upstream side in the sheet carrying-out direction from the nip section of the conveying-out drive roller R 4  and the conveying-out follower roller R 11 . More concretely, the predetermined region SR is a region in which the position of the inversed leading end in the sheet conveying-out direction of the preceding sheet S 1  being moved with the shifting of the stop member  123  does not interfere with the position of the leading end in the sheet conveying-in direction of the succeeding sheet S 2  being conveyed in from the sheet conveying-in conveyance path r 11 . That is, if the position of the inversed leading end in the sheet conveying-out direction of the preceding sheet S 1  is within the range of the predetermined region SR, the position of the leading end in the sheet conveying-in direction of the succeeding sheet S 2  being conveyed in from the sheet conveying-in conveyance path r 11  is located below from the predetermined region SR and does not interfere with the preceding sheet S 1 . 
     According to the structure of the first embodiment according to the sheet aligning apparatus B 1  of the present invention, since the shifting speed of the stop member  123  at the time of stopping at the first stop position P 1  is controlled, it is possible to prevent the phenomenon that the inversed leading end of the preceding sheet S 1  passes over predetermined region SR due to inertia and reaches the conveying-out drive roller R 4 . Therefore, it is possible to prevent the problem that the inversed leading end of a sheet S 1  is pinched between the conveying-out drive roller R 4  and the conveying-out follower roller R 11  of the conveyance path switching member G 1  returning from the retracting position and the sheet S 1  is left on the pinched condition even if the stop member  123  is shifted downward.
     (4) In  FIG. 6(   b ), the conveyance path switching member G 1  returns, and simultaneously the conveying-in drive roller R 3  returns to the sheet conveying-in conveyance path r 11  and the conveying-in drive roller R 3  rotating with a driving force comes in pressure contact with the carrying-in follower roller R 10 . Simultaneously, in the sheet storage conveyance path r 12 , the conveying-out drive roller R 4  and the conveying-out follower roller R 11  come in pressure contact with each other. The second succeeding sheet S 2  pinched and conveyed by the conveying roller R 2  is conveyed along the guide plate  111  of the sheet conveying-in conveyance path r 11 , then pinched and conveyed by the conveying-in drive roller R 3  and the carrying-in follower roller R 10 , and advances toward the sheet shifting section YS.   (5) In  FIG. 7(   a ), the second succeeding sheet S 2  is conveyed along the guide plate  121  of the sheet storage conveyance path r 12 , and after its leading end passes over the separated nip section of the conveying-in drive roller R 3  and the conveying-in follower roller R 10 , the stop member  123  is returned to the initial stop position P 0 . The leading end of the second succeeding sheet S 2  comes in contact with the stopping surface  123 A of the stop member  123  of the sheet storage section YS, and stops there. At this initial stop position P 0 , the second succeeding sheet S 2  is made on the condition that its whole surface is superimposed on the top of the preceding first sheet S 1 .   

     In the present embodiment, the predetermined number of sheets stored in the sheet storing section Y is set to two sheets. Therefore, when the number of sheets S stored in the sheet storing section Y becomes two sheets, the sheets S are conveyed out from the sheet storing section Y through the sheet storing path r 12 .
     (6) In  FIG. 7(   b ), as same as in  FIG. 6(   a ), the conveyance path switching member G 1  is actuated to separate the conveying-out follower roller R 11  from the conveying-out drive roller R 4 . Then, the stop member  123  is shifted by a motor M 3  above to a second stop position P 2  by the predetermined distance L 2  (for example, 50 mm) from the initial stop position P 0 , wherein the second stop position P 2  is located above further from the first stop position P 1  located above by the predetermined distance L 1  from the initial stop position P 0 . At this time, the top end (the inversed leading end) of the stacked two sheets S 1  and S 2  comes in contact with the stopping surface  124 A of the lengthwise aligning member  124 , and stops there, and the lengthwise aligning of the two sheets S 1  and S 2  is carried out with high precision. The stop position of the top end (the inversed leading end) of the two sheets S 1  and S 2  having been lengthwise aligned is located at the downstream side in the conveying direction from the nip position of the conveying-out drive roller R 4 . At the same time with the lengthwise aligning or after it has been completed, a widthwise aligning section  122  is driven by a motor M 4  to conduct a widthwise aligning by pressing the side edges of the sheets S 1  and S 2  in a width direction.   (7) In  FIG. 8(   a ), as same as in  FIG. 6(   b ), the conveyance path switching member G 1  returns, and at the same time, the conveying-in drive roller  23  also returns. Then, the conveying-in drive roller R 3  rotating with a driving force and the carrying-in follower roller R 10  come in contact with each other and pinch the leading end of the third sheet S 3  so as to make it possible to convey the third sheet S 3 . Simultaneously, the conveying-out drive roller R 4  and the conveying-out follower roller R 11  come in contact with each other and pinch the top end (the inversed leading end) of the stacked sheets S 1  and S 2 .   (8) In  FIG. 8(   b ), the lengthwise aligning member  124  is actuated by a solenoid SOL 3  and retracts from the sheet conveying path r 13 . The two sheets S 1  and S 2  pinched between the conveying-out drive roller R 4  and the conveying-out follower roller R 11  are conveyed by the rotation of the conveying-out drive roller R 4 , and subsequently the two sheets S 1  and S 2  are pinched by an intermediate conveying roller R 5 , and is discharged to a next step. Almost the same time, the third sheet S 3  pinched between the conveying-in drive roller R 3  and the conveying-in follower roller R 10  is conveyed and proceeds towards the sheet storage section  12 .   

     Here, although the number of sheets of the sheet S stored in the sheet storage section  12  is made two sheets in this embodiment, the present invention is not limited to this embodiment. It may be structured that the number of sheets is set in accordance with the post processing characteristic of the post processing apparatus FS connected to the sheet aligning apparatus B 1 . 
       FIG. 9  is a schematic structural diagram for explaining the structure and operations of a driving section of the second embodiment according to the sheet aligning apparatus B 1  of the present invention. 
     The driving section of the second embodiment of the sheet aligning apparatus B 1  is similar to the driving section of the first embodiment and a member having the same function is applied with the same reference symbol. Therefore, the explanation for such a member is omitted, and different structures and different operations are explained with reference to drawing. 
     The point of the second embodiment different from the first embodiment is a point that a sheet regulating member  129  is arranged in order to prevent the inversed leading end of a sheet S 1  from proceeding over without stopping a predetermined region SR when the stop member  123  is shifted from the initial stop position P 0  to the first stop position P 1 . 
     In  FIG. 9 , the sheet regulating member  129  is arranged at an upstream position (within the boundary of predetermined region SR) in the sheet conveying direction from the conveying-out drive roller R 4  on the sheet storage conveyance path r 12 , and is structured to be rockable so as to proceed on or retract from the sheet storage conveyance path r 12 . The rocking action of the sheet regulating member  129  is driven by a solenoid SOL 4  as a sheet regulating member driving section connected with a well-known link mechanism. 
     The sheet regulating member  129  is actuated to proceed onto the sheet storage conveyance path r 12  (the position indicated with a dotted line in  FIG. 9 ) at the time of shifting (lifting) up the stop member  123  from the initial stop position P 0  to the first stop position P 1 . Further, at the time of shifting (lowering) down the stop member  123  from the first stop position P 1  to the initial stop position P 0 , the sheet regulating member  129  is actuated to retract from the sheet storage conveyance path r 12  (the position indicated with a solid line in  FIG. 9 ). 
     A sheet S 1  moves with the movement of the stop member  123  being shifted from the initial stop position P 0  to the first stop position P 1 . When the stop member  123  stops at the first stop position P 1 , the position of the inversed leading end of the sheet S 1  in the conveying-out direction tends to go up and pass over the predetermined region SR due to the inertia of the sheet S 1 . At this time, since the sheet regulating member  129  proceed into the sheet storage conveyance path r 12 , the inversed leading end of the sheet S 1  in the conveying-out direction comes in contact with the sheet regulating member  129 , whereby the going-up of the sheet S 1  is regulated. 
     According to the second embodiment, even if the shifting speed of the stop member  123  being shifted from the initial stop position P 0  to the first stop position P 1  is fast, the inversed leading end of the sheet S 1  in the conveying-out direction is stopped within the predetermined region SR. For this reason, the inversed leading end of the sheet S 1  in the conveying-out direction does not reach the nip section between the conveying-out drive roller R 4  and the conveying-out follower roller R 11 , whereby it is possible to prevent the problem that the sheet S 1  is pinched by the nip section and a conveyance failure is caused by the pinched sheet S 1 . 
       FIG. 10  is a schematic structural diagram for explaining the structure and operations of the driving section of the third embodiment according to the sheet aligning apparatus B 1  of the present invention. 
     The driving section of the third embodiment of the sheet aligning apparatus B 1  is similar to the driving section of the first embodiment and a member having the same function is applied with the same reference symbol. Therefore, the explanation for such a member is omitted, and different structures and different operations are explained with reference to drawing. 
     The point of the third embodiment different from the first embodiment is a point that sheet pinching members  123 B and  123 C capable of contacting to or separating from a sheet S 1  are arranged in order to prevent the inversed leading end of a sheet S 1  from passing over a predetermined region SR due to inertia when the stop member  123  is shifted from the initial stop position P 0  to the first stop position P 1 . 
     In  FIG. 10 , the sheet pinching members  123 B and  123 C are arranged on the stop member  123  so as to be rockable, and are structured to pinch the both sides of a sheet S 1  at a portion near the inversed back end of the sheet S 1  coming in contact with the stopping surface  123 A of the stop member  123 . The rocking action of the sheet pinching members  123 B and  123 C is driven by a solenoid SOL 5  as a sheet pinching member driving section connected with a well-known link mechanism. 
     The sheet pinching members  123 B and  123 C are actuated to pinch the sheet S 1  (the position indicated with a solid line in  FIG. 10 ) at the time of shifting (lifting) up the stop member  123  from the initial stop position P 0  to the first stop position P 1 . Further, at the time of shifting (lowering) down the stop member  123  from the first stop position P 1  to the initial stop position P 0 , the sheet pinching members  123 B and  123 C are actuated to separate from the sheet S 1  (the position indicated with a dotted line in  FIG. 10 ). 
     A sheet S 1  moves with the movement of the stop member  123  being shifted from the initial stop position P 0  to the first stop position P 1 . When the stop member  123  stops at the first stop position P 1 , the position of the inversed leading end of the sheet S 1  in the conveying-out direction tends to separate from the stopping surface  123 A of the stop member  123  and go up due to the inertia of the sheet S 1 . At this time, since the sheet pinching members  123 B and  123 C pinch the neighborhood of the inversed back end of the sheet S 1 , the going-up of the sheet S 1  is refrained. 
     According to the third embodiment, even if the shifting speed of the stop member  123  being shifted from the initial stop position P 0  to the first stop position P 1  is fast, the neighborhood of the inversed back end of the sheet S 1  is pinched, and the going-up of the sheet S 1  is refrained, whereby the inversed leading end of the sheet S 1  is stopped within the predetermined region SR. For this reason, the inversed leading end of the sheet S 1  does not reach the nip section between the conveying-out drive roller R 4  and the conveying-out follower roller R 11 , whereby it is possible to prevent the problem that the sheet S 1  is pinched by the nip section and a conveyance failure is caused by the pinched sheet S 1 . 
       FIG. 11  is a control block diagram showing a command system at the time of controlling operations of each part by the control section  9 B in the first to third embodiments of the sheet aligning apparatus B 1  according to the present invention. 
     As shown in  FIG. 11 , the control section  9 B controls the operations of motors M 1 , M 2 , M 3  and solenoids SOL 3 , SOL 4 , and SOL 5  in response to sheet kind information, information about the number of sheets to be processed, and a sheet position information. 
     The sheet kind information is information on the size, thickness, material, and the like of a sheet, and is information set beforehand in the image forming apparatus main body A or information from a sensor provided in each portion, and the sheet kind information is inputted into the control section  9 B as an electrical signal. 
     The control section  9 B controls the speed of the motors M 1 , M 2 , and M 3  based on the sheet kind information. 
     Further, the initial stop position P 0  is made as a fixed position in the above embodiments. However, by changing the setting of the initial stop position P 0  in accordance with the size of a sheet, a sheet of different sizes can be coped with. 
     The information about the number of sheets to be processed is information in connection with the number of sheets to be conveyed out from the image forming apparatus main body A, and is information about the sum number of sheets per one job and information about the order number of a sheet being conveyed, and the information about the number of sheets to be processed is inputted into the control section  9 B as an electrical signal. 
     The control section  9 B controls the speed of the motors M 1 , M 2 , and M 3  based on the information about the number of sheets to be processed. 
     The sheet position information is information inputted into the control section  9 B as an electrical signal from sheet position detecting sensors arranged in the image forming apparatus main body A, an intermediate conveyance unit B and so on. 
     The control section  9 B controls the On-Off actions and speed of the motors M 1 , M 2 , and M 3  and the On-Off actions of the solenoids SOL 3 , SOL 4 , and SOL 5  based on the sheet position information. 
     Next, the timing of operations of the sheet aligning apparatus B 1  in the second and third embodiments according to the present invention is explained with reference to  FIG. 12 . 
       FIG. 12  is a timing chart with regard to the sheet aligning apparatus B 1  in the second and third embodiments according to the present invention. 
     First, the timing of operations of the sheet aligning apparatus B 1  in the second embodiment according to the present invention is explained. 
     In the second embodiment, after the preceding sheet S 1  has been conveyed in the sheet shifting section YS, the conveying-out follower roller R 11  is released from the pressure contact with the conveying-out drive roller R 4  by the solenoid SOL 1 , whereby the sheet storage conveyance path r 12  is opened in the direction toward the sheet conveying-out path. 
     Then, the motor M 3  is driven to shift the stop member  123  in the sheet shifting section YS from the initial stop position P 0  to the first stop position P 1  and to stop the stop member  123  at the first stop position P 1 . Thereafter, before the stop member  123  is shifted downward, the solenoid SOL 1  is turned off electricity, and in turn the conveying-out drive roller R 4  and the conveying-out follower roller R 11  are brought into pressure contact with each other again. 
     When the succeeding sheet S 2  is conveyed into the sheet storage conveyance path r 12  from the sheet conveying-in conveyance path r 11 , the motor M 3  is driven in connection with this conveyance, the stop member  123  is shifted downward to the initial stop position P 0 . 
     The solenoid SOL 1  is turned on electricity again, and the conveying-out follower roller R 11  is released from pressure contact with the conveying-out drive roller R 4 . 
     The solenoid SOL 4  used for this embodiment turns on electricity just before or after the turning on electricity for the solenoid SOL 1  for the second time, and the sheet regulating member  129  is retracted from the sheet storage conveyance path r 12  (refer to  FIG. 9 ). 
     Then, the stop member  123  is shifted to the second stop position P 1  by the driving of the motor M 3 , and the aligning for the sheets S is conducted. Thereafter, the solenoid SOL 1  is turned off electricity again, whereby the conveying-out drive roller R 4  and the conveying-out follower roller R 11  are brought in contact with each other again so as to pinch the sheets S therebetween. 
     Subsequently, the lengthwise aligning member  124  is retracted from the sheet storage conveyance path r 12  by the solenoid SOL 3 , and then the conveying-out drive roller R 4  is rotated by the motor M 2 , and the sheets S are conveyed out towards the next process. During the conveying-out of the sheets S, the motor M 3  is driven, and the stop member  123  is shifted to the initial stop position P 0 . 
     After the sheet is conveyed out from the conveying-out drive roller R 4 , the motor M 2  stop rotation. Then, the solenoid SOL 3  and SOL 4  are turned off electricity, and the lengthwise aligning member  124  and the sheet regulating member  129  proceed into the sheet storage conveyance path r 12  again. 
     Next, the timing of operations of the sheet aligning apparatus B 1  in the third embodiments according to the present invention is explained. 
     Since the timing of operations of the third embodiment is similar to the timing of operations of the second embodiment, only different points are explained. 
     The point that the third embodiment differs from the second embodiment is a point that although the operation of solenoid SOL 4  in the second embodiment is conducted at the time of shifting the stop member  123  to the second stop position, the operation of the solenoid SOL 5  in the third embodiment is conducted at the time of shifting the stop member  123  to the first stop position. 
     That is, in the third embodiment, the solenoid SOL 5  is turned on electricity just before or after the solenoid SOL 1  is turned on electricity before the stop member  123  is shifted to the first stop position P 1 , whereby the sheet pinching members  123 B and  123 C according to the present invention are actuated so as to pinch the preceding sheet on the sheet shifting section YS. 
     After the stop member  123  is shifted to the first stop position P 1 , just before the stop member  123  is shifted to the initial stop position P 0  again, the solenoid SOL 5  is turned off electricity, whereby the pinching of the preceding sheet S 1  by the sheet pinching members  123 B and  123 C is canceled. 
     Since the timing of other operations in the third embodiment are the same as that of each section in the second embodiment except the action of the solenoid SOL 4  and the sheet regulating member  129 , the explanations for them are omitted. 
     Next, the operations of the sheet aligning apparatus B 1  according to the present invention in the first, second and third embodiments are explained with reference to  FIGS. 13 to 15 . 
       FIG. 13  is a flowchart for explaining the operations of the sheet aligning apparatus B 1  according to the present invention in the first embodiment. 
     First, the preceding sheet S 1  discharged from the discharging section  5 E of the image forming apparatus main body A is conveyed through the sheet conveying-in conveyance path r 11  and the sheet storage conveyance path r 12  and stored into the sheet shifting section YS of the sheet storage section  12  by the rotation of the conveying-in drive roller R 3  (Step S 11 ). 
     Next, the control section  9 B judges based on information about the number of processed sheets from the control section  9 A of the image forming apparatus main body A whether or not the number of sheets S 1  stored in the sheet shifting section YS reach the predetermined number (Step S 12 ). If the number of sheets does not reach the predetermined number (in Step S 12 , No), the operation proceeds to Step S 13 . In contrast, if the number of sheets reaches the predetermined number (in Step S 12 , Yes), the operation proceeds to Step S 18 . 
     In Step S 13 , the control section  9 B controls the rotating speed of the motor M 3 , changes the shifting speed of the stop member  123 , and shifts the stop member  123  from the initial stop position P 0  to the first stop position P 1  (step S 13 ). 
     When the stop member  123  is located at the first stop position P 1  and the inversed leading end of the preceding sheet S 1  in the sheet conveying direction is located in the predetermined region SR, the control section  9 B rotates the conveying-in drive roller R 3  to convey in the succeeding sheet S 2  from the sheet conveying-in conveyance path r 11  to the sheet storage conveyance path r 12  (Step S 14 ). 
     In accordance with the conveying-in of the succeeding sheet S 2  in the sheet storage conveyance path r 12 , the control section  9 B shifts the stop member  123  from the first stop position P 1  to the initial stop position P 0  (Step S 15 ). 
     While the stop member  123  stops at the initial stop position P 0 , the succeeding sheet S 2  is stored in the sheet shifting section YS, and is piled up on the preceding sheet S 1  (Step S 16 ). 
     The control section  9 B judges whether or the number of sheets S stored in the sheet shifting section YS reach the predetermined number (step S 17 ), if the number of sheets S reaches the predetermined number (in Step S 17 , Yes), the operation proceeds to Step S 18 , and if the number of sheets S does not reach the predetermined number (in step S 17 , No), the operation returns to Step S 13 . 
     If the number of sheets S stored in the sheet shifting section YS does not reach the predetermined number, the operation returns to step S 13 , and the operations of from Step S 13  to Step S 17  are repeated. 
     If the number of sheets S stored in the sheet shifting section YS reaches the predetermined number, the operation proceeds to Step S 18 , and the control section  9 B shifts the stop member  123  from the initial stop position P 0  to the second stop position P 2 . Further, before the stop member  123  reaches the second stop position P 2 , the solenoid SOL 1  is actuated to rock the conveyance path switching member G 1  so that the conveying-out follower roller R 11  is separated from the conveying-out drive roller R 4 . Furthermore, the solenoid SOL 3  is actuated to make the lengthwise aligning member  124  proceed into the sheet storage conveyance path r 12  (Step S 18 ). 
     When the stop member  123  reaches the second stop position P 2 , the inversed leading end in the sheet conveying-out direction of the sheets S stored in the sheet shifting section YS come in contact with the lengthwise aligning member  124 , whereby the aligning of the sheets S in the conveying direction is performed. Furthermore, the motor M 4  is driven to actuate the widthwise aligning section  122 , whereby the aligning of the sheets S in the sheet width direction is performed (Step S 19 ). 
     When the aligning of sheets S has completed, the conveyance path switching member G 1  is made to rock so that the conveying-out follower roller R 11  is brought in pressure contact with the conveying-out drive roller R 4  so as to pinch the aligned sheets S therebetween. Subsequently, the motor M 2  is driven to rotate the conveying-out drive roller R 4  so that the sheets S are conveyed out toward the next step (Step S 20 ). 
       FIG. 14  is a flowchart for explaining the procedure of operations of the sheet aligning apparatus B 1  in the second embodiment according to the present invention. 
     First, the preceding sheet S 1  discharged from the discharging section  5 E of the image forming apparatus main body A is conveyed through the sheet conveying-in conveyance path r 11  and the sheet storage conveyance path r 12  and stored into the sheet shifting section YS of the sheet storage section  12  by the rotation of the conveying-in drive roller R 3  (Step S 31 ). 
     Next, the control section  9 B judges based on information about the number of processed sheets from the control section  9 A of the image forming apparatus main body A whether or not the number of sheets S 1  stored in the sheet shifting section YS reach the predetermined number (Step S 32 ). If the number of sheets does not reach the predetermined number (in Step S 32 , No), the operation proceeds to Step S 33 . In contrast, if the number of sheets reaches the predetermined number (in Step S 32 , Yes), the operation proceeds to Step S 39 . 
     In Step S 33 , the control section  9 B operates the solenoid SOL 4  such that the sheet regulating member  129  advances into the sheet storage conveyance path r 12  (Step S 33 ). 
     Subsequently, the control section  9 B drives the motor M 3  to shift the stop member  123  from the initial stop position P 0  to the first stop position P 1  (step S 34 ). 
     When the stop member  123  is located at the first stop position P 1  and the inversed leading end of the preceding sheet S 1  in the sheet conveying direction is located in the predetermined region SR, the control section  9 B rotates the conveying-in drive roller R 3  to convey the succeeding sheet S 2  from the sheet conveying-in conveyance path r 11  into the sheet storage conveyance path r 12  (Step S 35 ). 
     In accordance with the conveying-in of the succeeding sheet S 2  in the sheet storage conveyance path r 12 , the control section  9 B shifts the stop member  123  from the first stop position P 1  to the initial stop position P 0  (Step S 36 ). 
     While the stop member  123  stops at the initial stop position P 0 , the succeeding sheet S 2  is stored in the sheet shifting section YS, and is piled up on the preceding sheet S 1  (Step S 37 ). 
     The control section  9 B judges whether or the number of sheets S stored in the sheet shifting section YS reach the predetermined number (step S 38 ), if the number of sheets S reaches the predetermined number (in Step S 38 , Yes), the operation proceeds to Step S 39 , and if the number of sheets S does not reach the predetermined number (in step S 38 , No), the operation returns to Step S 34 . 
     If the number of sheets S stored in the sheet shifting section YS does not reach the predetermined number, the operation returns to step S 34 , and the operations of from Step S 34  to Step S 38  are repeated. 
     If the number of sheets S stored in the sheet shifting section YS reaches the predetermined number, the operation proceeds to Step S 39 , and the control section  9 B actuates the solenoid SOL 4  to retract the sheet regulating member  129  from the sheet storage conveyance path r 12  (Step S 39 ). 
     Subsequently, the control section  9 B shifts the stop member  123  from the initial stop position P 0  to the second stop position P 2 . Further, before the stop member  123  reaches the second stop position P 2 , the solenoid SOL 1  is actuated to rock the conveyance path switching member G 1  so that the conveying-out follower roller R 11  is separated from the conveying-out drive roller R 4 . Furthermore, the solenoid SOL 3  is actuated to make the lengthwise aligning member  124  to proceed into the sheet storage conveyance path r 12  (Step S 40 ). 
     When the stop member  123  reaches the second stop position P 2 , the inversed leading end in the sheet conveying-out direction of the sheets S stored in the sheet shifting section YS come in contact with the lengthwise aligning member  124 , whereby the aligning of the sheets S in the conveying direction is performed. Furthermore, the motor M 4  is driven to actuate the widthwise aligning section  122 , whereby the aligning of the sheets S in the sheet width direction is performed (Step S 41 ). 
     When the aligning of sheets S has completed, the conveyance path switching member G 1  is made to rock so that the conveying-out follower roller R 11  is brought in pressure contact with the conveying-out drive roller R 4  so as to pinch the aligned sheets S therebetween. Subsequently, the motor M 2  is driven to rotate the conveying-out drive roller R 4  so that the sheets S are conveyed out toward the next step (Step S 42 ). 
       FIG. 15  is a flowchart for explaining the procedure of operations of the sheet aligning apparatus B 1  in the third embodiment according to the present invention. 
     First, the preceding sheet S 1  discharged from the discharging section  5 E of the image forming apparatus main body A is conveyed through the sheet conveying-in conveyance path r 11  and the sheet storage conveyance path r 12  and stored into the sheet shifting section YS of the sheet storage section  12  by the rotation of the conveying-in drive roller R 3  (Step S 51 ). 
     Next, the control section  9 B judges based on information about the number of processed sheets from the control section  9 A of the image forming apparatus main body A whether or not the number of sheets S 1  stored in the sheet shifting section YS reach the predetermined number (Step S 52 ). If the number of sheets does not reach the predetermined number (in Step S 52 , No), the operation proceeds to Step S 53 . In contrast, if the number of sheets reaches the predetermined number (in Step S 52 , Yes), the operation proceeds to Step S 60 . 
     In Step S 53 , the control section  9 B operates the solenoid SOL 5  to actuate the sheet pinching member  123 B and  123  to pinch the neighborhood of the inversed back end of the sheet in the sheet conveying-out direction (Step S 53 ). 
     Subsequently, the control section  9 B drives the motor M 3  to shift the stop member  123  from the initial stop position P 0  to the first stop position P 1  (step S 54 ). 
     The control section  9 B operates again the solenoid SOL 5  to actuate the sheet pinching member  123 B and  123  to cancel the pinching of the sheet (Step S 56 ). 
     When the stop member  123  is located at the first stop position P 1  and the inversed leading end of the preceding sheet S 1  in the sheet conveying direction is located in the predetermined region SR, the control section  9 B rotates the conveying-in drive roller R 3  to convey the succeeding sheet S 2  from the sheet conveying-in conveyance path r 11  into the sheet storage conveyance path r 12  (Step S 56 ). 
     In accordance with the conveying-in of the succeeding sheet S 2  in the sheet storage conveyance path r 12 , the control section  9 B shifts the stop member  123  from the first stop position P 1  to the initial stop position P 0  (Step S 57 ). 
     While the stop member  123  stops at the initial stop position P 0 , the succeeding sheet S 2  is stored in the sheet shifting section YS, and is piled up on the preceding sheet S 1  (Step S 58 ). 
     The control section  9 B judges whether or the number of sheets S stored in the sheet shifting section YS reach the predetermined number (step S 59 ), if the number of sheets S reaches the predetermined number (in Step S 59 , Yes), the operation proceeds to Step S 60 , and if the number of sheets S does not reach the predetermined number (in step S 59 , No), the operation returns to Step S 53 . 
     If the number of sheets S stored in the sheet shifting section YS does not reach the predetermined number, the operation returns to step S 53 , and the operations of from Step S 53  to Step S 59  are repeated. 
     If the number of sheets S stored in the sheet shifting section YS reaches the predetermined number, the operation proceeds to Step S 60 , and the control section  9 B shifts the stop member  123  from the initial stop position P 0  to the second stop position P 2 . Further, before the stop member  123  reaches the second stop position P 2 , the solenoid SOL 1  is actuated to rock the conveyance path switching member G 1  so that the conveying-out follower roller R 11  is separated from the conveying-out drive roller R 4 . Furthermore, the solenoid SOL 3  is actuated to make the lengthwise aligning member  124  to proceed into the sheet storage conveyance path r 12  (Step S 60 ). 
     When the stop member  123  reaches the second stop position P 2 , the inversed leading end in the sheet conveying-out direction of the sheets S stored in the sheet shifting section YS come in contact with the lengthwise aligning member  124 , whereby the aligning of the sheets S in the conveying direction is performed. Furthermore, the motor M 4  is driven to actuate the widthwise aligning section  122 , whereby the aligning of the sheets S in the sheet width direction is performed (Step S 61 ). 
     When the aligning of sheets S has completed, the conveyance path switching member G 1  is made to rock so that the conveying-out follower roller R 11  is brought in pressure contact with the conveying-out drive roller R 4  so as to pinch the aligned sheets S therebetween. Subsequently, the motor M 2  is driven to rotate the conveying-out drive roller R 4  so that the sheets S are conveyed out toward the next step (Step S 62 ). 
     Here, in order to perform the lengthwise aligning more exactly, when the stop member  123  stops at the second stop position P 2 , the above embodiments are structured such that the lengthwise aligning is performed by pinching the sheets between the stop member  123  and the lengthwise aligning member  124 . However, the lengthwise aligning may performed without the lengthwise aligning member  124 . That is, the lengthwise aligning is performed by bringing sheets in contact with a stop member without providing the lengthwise aligning member  124 . The structure in which the lengthwise aligning member  124  is not provided is the same structure shown in  FIG. 2  except the lengthwise aligning member  124  and the solenoid SOL 3 , and since other structure and operations are the same as that of the first, second and third embodiments, the explanation for them are omitted. 
     As describe above, the object of the present invention is attained by the sheet aligning apparatus and the image forming system employing the following preferable structures. 
     1. A sheet aligning apparatus comprises: 
     a sheet storage conveyance path to convey in or convey out sheets; 
     a sheet conveying-in conveyance path having a meeting point with the sheet storage conveyance path at a downstream side in a sheet conveying-in direction and to convey in sheets toward the meeting point; 
     a sheet conveying-in section provided at an upstream side in the sheet conveying-in direction on the sheet conveying-in conveyance path from the meeting point and to convey in sheets toward the meeting point; 
     a stop member having a bumping stop surface to stop sheets conveyed into the sheet storage conveyance path by coming in contact with the leading end of the sheets in a sheet conveying-in direction and capable of shifting along the sheet storage conveyance path; 
     a sheet storing section constituted by the sheet storage conveyance path and the stop member and to store sheets conveyed into the sheet storage conveyance path; 
     a stop member shifting section to shift the stop member from an initial stop position to wait at the time of storing sheets to a first stop position to prevent interruption of succeeding sheets, or to a second stop position to align plural sheets stored in the sheet storing section in a sheet conveying direction; 
     a sheet conveying-out section provided at a downstream side from the meeting point in the sheet conveying-out direction and to convey out sheets from the sheet storage conveyance path; and 
     a lengthwise aligning member provided at a downstream side from the sheet conveying-out section in the sheet conveying-out direction and to align sheets in the sheet conveying direction by coming in contact with the inversed leading end in the sheet conveying-out direction of the sheets shifted with the shifting of the stop member toward the second stop position; 
     wherein the stop member shifting section controls the shifting speed at the time of shifting the stop member from the initial stop position to the first stop position in such a way that the inversed leading end in the conveying-out direction of the sheets is prevented from reaching the sheet conveying-out section due to inertia of the sheets right after the stop member have been shifted and stopped at the first stop position. 
     2. A sheet aligning apparatus comprises: 
     a sheet storage conveyance path to convey in or convey out sheets; 
     a sheet conveying-in conveyance path having a meeting point with the sheet storage conveyance path at a downstream side in a sheet conveying-in direction and to convey in sheets toward the meeting point; 
     a sheet conveying-in section provided at an upstream side in the sheet conveying-in direction on the sheet conveying-in conveyance path from the meeting point and to convey in sheets toward the meeting point; 
     a stop member having a bumping stop surface to stop sheets conveyed into the sheet storage conveyance path by coming in contact with the leading end of the sheets in a sheet conveying-in direction and capable of shifting along the sheet storage conveyance path; 
     a sheet storing section constituted by the sheet storage conveyance path and the stop member and to store sheets conveyed into the sheet storage conveyance path; 
     a stop member shifting section to shift the stop member from an initial stop position to wait at the time of storing sheets to a first stop position to prevent interruption of succeeding sheets, or to a second stop position to align plural sheets stored in the sheet storing section in a sheet conveying direction; 
     a sheet conveying-out section provided at a downstream side from the meeting point in the sheet conveying-out direction and to convey out sheets from the sheet storage conveyance path; 
     a lengthwise aligning member provided at a downstream side from the sheet conveying-out section in the sheet conveying-out direction and to align sheets in the sheet conveying direction by coming in contact with the inversed leading end in the sheet conveying-out direction of the sheets shifted with the shifting of the stop member toward the second stop position; 
     a sheet regulating member provided between the sheet conveying-out section and the meeting point and to regulate the inversed leading end in the conveying-out direction of the sheets from reaching the sheet conveying-out section due to inertia of the sheets right after the stop member have been shifted and stopped at the first stop position; and 
     a sheet regulating member driving section to make the sheet regulating member advance into or retract from the sheet storage conveyance path; 
     wherein the sheet regulating member driving section is controlled in such a way that when the stop member shifting section shifts the stop member from the initial stop position to the first stop position, the sheet regulating member driving section makes the sheet regulating member advance into the sheet storage conveyance path before the stop member is shifted to the first stop position, and when the stop member shifting section shifts the stop member from the initial stop position to the second stop position, the sheet regulating member driving section makes the sheet regulating member retract from the sheet storage conveyance path before the stop member is shifted to the second stop position. 
     3. A sheet aligning apparatus comprises: 
     a sheet storage conveyance path to convey in or convey out sheets; 
     a sheet conveying-in conveyance path having a meeting point with the sheet storage conveyance path at a downstream side in a sheet conveying-in direction and to convey in sheets toward the meeting point; 
     a sheet conveying-in section provided at an upstream side in the sheet conveying-in direction on the sheet conveying-in conveyance path from the meeting point and to convey in sheets toward the meeting point; 
     a stop member having a bumping stop surface to stop sheets conveyed into the sheet storage conveyance path by coming in contact with the leading end of the sheets in a sheet conveying-in direction and capable of shifting along the sheet storage conveyance path; 
     a sheet storing section constituted by the sheet storage conveyance path and the stop member and to store sheets conveyed into the sheet storage conveyance path; 
     a stop member shifting section to shift the stop member from an initial stop position to wait at the time of storing sheets to a first stop position to prevent interruption of succeeding sheets, or to a second stop position to align plural sheets stored in the sheet storing section in a sheet conveying direction; 
     a sheet conveying-out section provided at a downstream side from the meeting point in the sheet conveying-out direction and to convey out sheets from the sheet storage conveyance path; 
     a lengthwise aligning member provided at a downstream side from the sheet conveying-out section in the sheet conveying-out direction and to align sheets in the sheet conveying direction by coming in contact with the inversed leading end in the sheet conveying-out direction of the sheets shifted with the shifting of the stop member toward the second stop position; 
     a sheet pinching member arranged in the vicinity of the stop surface of the bumping stop surface of the stop member and capable of coming in contact with or separating from the sheet in the sheet storage conveyance path so as to pinch the sheet from both sides of the sheets in the thickness direction; and 
     a sheet pinching member driving section to make the sheet pinching member take a pinching position to come in contact with the sheet or a pinching releasing position to separate from the sheet; 
     wherein the sheet pinching member driving section is controlled in such a way that when the stop member shifting section shifts the stop member from the initial stop position to the first stop position, the sheet pinching member driving section makes the sheet pinching member take the pinching position before the stop member is shifted to the first stop position, and when the stop member shifting section shifts the stop member from the initial stop position to the second stop position, the sheet pinching member driving section makes the sheet pinching member take the pinching releasing position before the stop member is shifted to the second stop position. 
     4. A sheet aligning apparatus comprises: 
     a sheet storage conveyance path to convey in or convey out sheets; 
     a sheet conveying-in conveyance path having a meeting point with the sheet storage conveyance path at a downstream side in a sheet conveying-in direction and to convey in sheets toward the meeting point; 
     a sheet conveying-in section provided at an upstream side in the sheet conveying-in direction on the sheet conveying-in conveyance path from the meeting point and to convey in sheets toward the meeting point; 
     a sheet conveying-out section provided at a downstream side from the meeting point in the sheet conveying-out direction and to convey out sheets from the sheet storage conveyance path; 
     a stop member having a bumping stop surface to stop sheets conveyed into the sheet storage conveyance path by coming in contact with the leading end of the sheets in a sheet conveying-in direction and capable of shifting along the sheet storage conveyance path; 
     a sheet storing section constituted by the sheet storage conveyance path and the stop member and to store sheets conveyed into the sheet storage conveyance path; and 
     a stop member shifting section to shift the stop member from an initial stop position to wait at the time of storing sheets to a first stop position to prevent interruption of succeeding sheets, or to a second stop position to align plural sheets stored in the sheet storing section in a sheet conveying direction; 
     wherein the stop member shifting section controls the shifting speed at the time of shifting the stop member from the initial stop position to the first stop position in such a way that the inversed leading end in the conveying-out direction of the sheets is prevented from reaching the sheet conveying-out section due to inertia of the sheets right after the stop member have been shifted and stopped at the first stop position. 
     5. A sheet aligning apparatus comprises: 
     a sheet storage conveyance path to convey in or convey out sheets; 
     a sheet conveying-in conveyance path having a meeting point with the sheet storage conveyance path at a downstream side in a sheet conveying-in direction and to convey in sheets toward the meeting point; 
     a sheet conveying-in section provided at an upstream side in the sheet conveying-in direction on the sheet conveying-in conveyance path from the meeting point and to convey in sheets toward the meeting point; 
     a sheet conveying-out section provided at a downstream side from the meeting point in the sheet conveying-out direction and to convey out sheets from the sheet storage conveyance path; 
     a stop member having a bumping stop surface to stop sheets conveyed into the sheet storage conveyance path by coming in contact with the leading end of the sheets in a sheet conveying-in direction and capable of shifting along the sheet storage conveyance path; 
     a sheet storing section constituted by the sheet storage conveyance path and the stop member and to store sheets conveyed into the sheet storage conveyance path; 
     a stop member shifting section to shift the stop member from an initial stop position to wait at the time of storing sheets to a first stop position to prevent interruption of succeeding sheets, or to a second stop position to align plural sheets stored in the sheet storing section in a sheet conveying direction; 
     a sheet regulating member provided between the sheet conveying-out section and the meeting point and to regulate the inversed leading end in the conveying-out direction of the sheets from reaching the sheet conveying-out section due to inertia of the sheets right after the stop member have been shifted and stopped at the first stop position; and 
     a sheet regulating member driving section to make the sheet regulating member advance into or retract from the sheet storage conveyance path; 
     wherein the sheet regulating member driving section is controlled in such a way that when the stop member shifting section shifts the stop member from the initial stop position to the first stop position, the sheet regulating member driving section makes the sheet regulating member advance into the sheet storage conveyance path before the stop member is shifted to the first stop position, and when the stop member shifting section shifts the stop member from the initial stop position to the second stop position, the sheet regulating member driving section makes the sheet regulating member retract from the sheet storage conveyance path before the stop member is shifted to the second stop position. 
     6. A sheet aligning apparatus comprises: 
     a sheet storage conveyance path to convey in or convey out sheets; 
     a sheet conveying-in conveyance path having a meeting point with the sheet storage conveyance path at a downstream side in a sheet conveying-in direction and to convey in sheets toward the meeting point; 
     a sheet conveying-in section provided at an upstream side in the sheet conveying-in direction on the sheet conveying-in conveyance path from the meeting point and to convey in sheets toward the meeting point; 
     a sheet conveying-out section provided at a downstream side from the meeting point in the sheet conveying-out direction and to convey out sheets from the sheet storage conveyance path; 
     a stop member having a bumping stop surface to stop sheets conveyed into the sheet storage conveyance path by coming in contact with the leading end of the sheets in a sheet conveying-in direction and capable of shifting along the sheet storage conveyance path; 
     a sheet storing section constituted by the sheet storage conveyance path and the stop member and to store sheets conveyed into the sheet storage conveyance path; 
     a stop member shifting section to shift the stop member from an initial stop position to wait at the time of storing sheets to a first stop position to prevent interruption of succeeding sheets, or to a second stop position to align plural sheets stored in the sheet storing section in a sheet conveying direction; 
     a sheet pinching member arranged in the vicinity of the stop surface of the bumping stop surface of the stop member and capable of coming in contact with or separating from the sheet in the sheet storage conveyance path so as to pinch the sheet from both sides of the sheets in the thickness direction; and 
     a sheet pinching member driving section to make the sheet pinching member take a pinching position to come in contact with the sheet or a pinching releasing position to separate from the sheet; 
     wherein the sheet pinching member driving section is controlled in such a way that when the stop member shifting section shifts the stop member from the initial stop position to the first stop position, the sheet pinching member driving section makes the sheet pinching member take the pinching position before the stop member is shifted to the first stop position, and when the stop member shifting section shifts the stop member from the initial stop position to the second stop position, the sheet pinching member driving section makes the sheet pinching member take the pinching releasing position before the stop member is shifted to the second stop position. 
     7. An image forming system, comprises: 
     an image forming section to form an image on a sheet, the sheet aligning apparatus described in any one of above 1 to 6, provided downstream side of the image forming apparatus in the sheet conveying direction and to receive the sheet on which an image is formed by the image forming apparatus, and a post processing apparatus provided downstream side of the sheet aligning apparatus and to conduct a post processing for the sheets discharged from the sheet aligning apparatus. 
     According to the structure of the present invention, when the stop member is shifted from the initial stop position to the first stop position in order to avoid the interference among sheets, it is possible to prevent a sheet from proceeding excessively due to the inertia of the sheet, whereby it is possible to provide a sheet aligning apparatus and a image forming system in which there is no problems, such as a sheet conveyance failure and a sheet alignment failure.