Patent Publication Number: US-7717414-B2

Title: Sheet processing apparatus and sheet processing method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sheet processing apparatus that feeds a sheet having an image formed thereon by a copying machine, a printer, a multifunction peripheral (MFP), or the like to a finisher and has a collating function. 
     2. Description of the Related Art 
     In recent years, among image forming apparatuses, there is an image forming apparatus in which a finisher is provided adjacent to an image forming apparatus main body in order to perform post-processing such as processing for sorting sheets after image formation and processing for applying staple processing to the sheets. An inserter may be arranged at a pre-stage of the finisher in order to feed sheets having images formed thereon to the finisher. 
     In a general inserter, since a user needs to arrange orders of sheets to be inserted in advance and insert the sheets, a burden is imposed on the user. 
     In JP-A-2001-270653, a collating device is described. In this example, prints are supplied from plural printing machines to plural trays on a belt conveyor, respectively, and the prints received by the trays are collected and stacked to collate the prints. However, in this example, since the plural trays and the belt conveyor are necessary, the apparatus is large in scale. 
     In JP-A-10-186741, an original conveying apparatus that copies plural originals by the number n and sorts the copies is described. In this example, a system for varying discharge speed at the time when a first sheet is discharged and at the time when second to nth sheets are discharged on the basis of the number of copies n is adopted. 
     However, since it is necessary to frequently switch discharge speed of the sheets, a structure of the apparatus is complicated. 
     Moreover, in JP-A-9-48531, a supplying apparatus that supplies sheets to a collating machine to bind the sheets is described. This example is a large-scale apparatus for bookbinding. 
     The present invention provides a sheet processing apparatus and a sheet processing method that can classify sheets into predetermined states and discharge the sheets. 
    
    
     
       DESCRIPTION OF THE DRAWING 
         FIG. 1  is a schematic diagram showing a sheet processing apparatus according to an embodiment of the invention; 
         FIG. 2  is a diagram showing a structure of a main part of the sheet processing apparatus of the invention in enlargement; 
         FIG. 3  is a schematic explanatory diagram for explaining a processing operation for sheets in the sheet processing apparatus of the invention; 
         FIGS. 4A to 4H  are explanatory diagrams for explaining operations of the sheet processing apparatus of the invention; 
         FIG. 5  is a block diagram showing a control system for the sheet processing apparatus of the invention; and 
         FIG. 6  is a flowchart for explaining operations of the sheet processing apparatus of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Throughout this description, the embodiments and examples shown should be considered as exemplars, rather than limitations on the apparatus of the present invention. 
     An embodiment of the invention will be hereinafter explained in detail with reference to the drawings. In the respective figures, identical components are denoted by identical reference numerals and signs. 
       FIG. 1  is a diagram showing an embodiment of a sheet processing apparatus of the invention. In  FIG. 1 , reference numeral  10  denotes an image forming apparatus, which is, for example, an MFP (Multi-Function Peripherals) as a complex machine, a printer, and a copying machine. 
     An original stand (not shown) is provided above a main body  11  of the image forming apparatus  10 . An auto document feeder (ADF)  12  is provided to be opened and closed freely on the original stand. An operation panel  13  is provided on the main body  11 . The operation panel  13  has an operation unit  14  including various keys and a display unit  15  of a touch panel type. 
     The main body  11  has a scanner unit  16  and a printer unit  17  in the inside thereof. Plural cassettes  18  having sheets of various sizes stored therein are provided below the main body  11 . The scanner unit  16  scans an original sent by the ADF  12  or an original placed on the original stand. 
     The printer unit  17  includes a photoconductive drum and a laser, scans and exposes the surface of the photoconductive drum with a laser beam from the laser, and forms an electrostatic latent image on the photoconductive drum. A charging device, a developing device, a transfer device, and the like are arranged around the photoconductive drum. The electrostatic latent image on the photoconductive drum is developed by the developing device and a toner image is formed on the photoconductive drum. The toner image is transferred onto a sheet by the transfer device. 
     A constitution of the printer  17  is not limited to the above example. There are various systems as the constitution of the printer  17 . A finisher  20  is arranged on a sheet discharge side of the image forming apparatus  10 . A sheet having an image formed thereon by the image forming apparatus  10  is conveyed to the finisher  20 . 
     The finisher  20  performs post-processing for the sheet supplied from the image forming apparatus  10  and performs, for example, sort processing and staple processing. When necessary, the finisher  20  folds the sheet in two and discharges the sheet. 
     The finisher  20  shown in  FIG. 1  has a stapling mechanism  21  for applying staple processing to a sheet bundle, a punching mechanism  31  for punching sheets, a sheet discharge tray  51 , and a fixed tray  52 . 
     The sheet discharge tray  51  is a movable type and receives the sheet bundle subjected to the staple processing. The stapling mechanism  21  includes an aligning device that aligns sheets, which are conveyed to the stapling mechanism  21 , in a width direction. The stapling mechanism  21  can also sort and discharge the sheets using this aligning device. 
     When the post-processing such as stapling is not performed, the stapling mechanism  21  directly discharges the sheets conveyed from the image forming apparatus  10  to the sheet discharge tray  51  or the fixed tray  52  without applying any processing to the sheets. 
     The stapling mechanism  21  of the finisher  20  will be briefly explained. Sheets supplied from the image forming apparatus  10  via the punching mechanism  31  are received by inlet rollers  22  provided near a delivery port of the finisher  20 . Sheet feeding rollers  23  are provided on a downstream side of the inlet rollers  22 . Sheets P received by the inlet rollers  22  are stacked on a processing tray  24  via the sheet feeding rollers  23  and the like. 
     The sheets stacked on the processing tray  24  are guided to a stapler  25  and subjected to staple processing. A conveyor belt  26  for conveying the sheets P subjected to the sort processing and the staple processing to the sheet discharge tray  51  is provided. 
     The sheets P conveyed by the conveyor belt  26  are discharged to the sheet discharge tray  51 . The sheet discharge tray  51  is lifted and lowered by a driving unit (now shown) to receive the sheets P. 
     The sheets P may be discharged to the sheet discharge tray  51  without being subjected to the staple processing. In this case, the sheets P are discharged without being dropped to the processing tray  24 . It is also possible to discharge the sheets P for which the post-processing is unnecessary to the fixed tray  52 . A conveying path is provided in order to guide the sheets P to the fixed tray  52 . The conveying path is not shown in the figure. 
     The punching mechanism  31  will be explained. The punching mechanism  31  is arranged between the image forming apparatus  10  and the stapling mechanism  21  and has a punch unit  32  and a dust box  33 . 
     The punch unit  32  is provided with a punching blade (not shown) for applying the punching processing to the sheets P. When this punching blade lowers, punch holes are opened in the sheets P. Punch dust generated by the punching processing falls into the dust box  33 . 
     Moreover, an inserter  40  forming an essential part of the invention is provided between the image forming apparatus  10  and the finisher  20 . The inserter  40  sequentially supplies sheets having images formed thereon to the finisher  20 . This inserter  40  has a collating mechanism for, when plural types of sheets are inserted therein in a stacked state, sequentially delivering the sheets to the finisher  20  in a designated order. The collating mechanism will be described later. 
     The inserter  40  has a sheet feeding tray  41 , a sheet feeding roller  42 , and a back roller  43 . Moreover, the inserter  40  has conveying rollers  53  and  54  for conveying the sheets P stored in the sheet feeding tray  41  to the punching mechanism  31  of the finisher  20 . 
     Plural rollers  55  and  56  for sheet conveyance are provided on a path extending from the image forming apparatus  10  to the inlet rollers  22  of the stapling mechanism  21 . The sheets P discharged from the image forming apparatus  10  are sent to the stapling mechanism  21  via the rollers  55  and  56 . The sheets conveyed by the conveying rollers  53  and  54  of the inserter  40  are sent to the stapling mechanism  21  via the rollers  56 . 
       FIG. 2  is a side view showing a structure of a main part of the inserter  40 . 
     In  FIG. 2 , the sheet feeding tray  41  has an aligning plate  44  that aligns the trailing end of the sheets P and a shutter  45  that receives the leading end of the sheets P. The shutter  45  opens, for example, in an upward direction when the sheets P are discharged. 
     The aligning plate  44  is capable of moving in a conveying direction of the sheets P (an arrow A direction). In order to move the aligning plate  44  in the arrow A direction, a rack  46  formed integrally with the sheet feeding tray  41  and a pinion  47  that meshes with this rack  46  are provided. The aligning plate  44  is moved by rotating the pinion  47  with a motor  48 . A belt mechanism and the like may be used as a moving mechanism for the aligning plate  44 . 
     The sheet feeding roller  42  and the back roller  43  are provided orthogonal to the conveying direction of the sheets P, formed in a columnar shape, and driven to rotate by motors  71  and  72  (described later with reference to  FIG. 5 ). The sheet feeding roller  42  and the back roller  43  are movable in a paper surface direction of the sheets P, i.e., a direction in which the stored sheets P are pressed, and a direction away from the sheets P. 
     The motors  71  and  72  that rotate the sheet feeding roller  42  and the back roller  43  and moving mechanisms for the sheet feeding roller  42  and the back roller  43  are attached to a plate  49 . The sheet feeding roller  42  has a function of rotating counterclockwise in the figure to discharge the sheets P from the sheet feeding tray  41 . The back roller  43  has a function of rotating clockwise in the figure to retract the sheets P in a direction opposite to the sheet feeding direction. 
     The inserter  40  according to the invention performs a collating operation shown in  FIG. 3 . For example, when a sheet bundle  100  stacked for each of plural types in such as manner as AAA, BBB, and CCC are stored in the sheet feeding tray  41 , the inserter  40  can select one sheet out of each of the plural types of sheets, combine the respective types in such a manner as ABC, ABC, and ABC, and discharge the sheets in good order. 
       FIGS. 4A to 4D  and  FIGS. 4E to 4H  are diagrams for explaining operations in performing such collating. 
     First,  FIG. 4A  shows a state in which three types of sheets A, B, and C are stacked in stages, for example, stacked in an order of A 1 , A 2 , A 3 , B 1 , B 2 , B 3 , C 1 , C 2 , and C 3  and stored in the sheet feeding tray  41 . Reference signs A 1 , A 2 , . . . represent a first sheet of a type A, a second sheet of the type A, and the like. 
     The types of the sheets mean sheets having images formed thereon on the basis of different originals, respectively, and do not mean sheet sizes and materials of the sheets. 
     When the sheet bundle  100  is stored in the sheet feeding tray  41 , the aligning plate  44  moves the sheet bundle  100  to the shutter  45  side, aligns the sheet bundle  100 , and returns to the original position. The sheet feeding roller  42  moves in a direction to the sheet bundle. The back roller  43  moves to a position apart from the sheet bundle. 
     In this state, the shutter  45  opens and the sheet feeding roller  42  rotates in the counterclockwise direction. Consequently, a sheet A 1  at the top is discharged by the sheet feeding roller  42  and guided to the rollers  53  (see  FIG. 2 ). 
     As shown in  FIG. 4B , the back roller  43  moves in the direction to the sheet bundle  100  and the sheet feeding roller  42  moves to a position apart from the sheet bundle  100 . In this state, the back roller  43  rotates in the clockwise direction. Consequently, a sheet A 2  at the top of the sheet bundle  100  is retracted by the back roller  43 . Moreover, as shown in  FIG. 4C , the next sheet A 3  is also sent to a retracted position by the back roller  43 . 
     When the sheets A 2  and A 3  are retracted, as shown in  FIG. 4D , the back roller  43  stops the rotation and the sheet feeding roller  42  moves in the direction to the sheet bundle  100  again. The sheet feeding roller  42  rotates in the counterclockwise direction and a sheet B 1  of the next type is discharged. 
     Moreover, as shown in  FIG. 4E , the sheet feeding roller  42  moves to a position apart from the sheet bundle  100  and the back roller  43  rotates in the clockwise direction. Consequently, the next sheets B 2  and B 3  are sent to the retracted position by the back roller  43 . 
     When the sheets B 2  and B 3  are retracted, as shown in  FIG. 4F , the back roller  43  stops the rotation, the sheet feeding roller  42  moves in the direction to the sheet bundle  100  again and rotates in the counterclockwise direction, and a sheet C 1  of the next type is discharged. 
     Thereafter, as shown in  FIG. 4G , the sheet feeding roller  42  moves to a position apart from the sheet bundle  100  and the back roller  34  rotates in the clockwise direction. Consequently, the next sheets C 2  and C 3  are sent to the retracted position by the back roller  43 . All the sheets A 2 , A 3 , B 2 , B 3 , C 2 , and C 3  on the sheet feeding tray  41  are sent to the retracted position. 
     In this state, the shutter  45  closes and the sheet feeding roller  42  and the back roller  43  moves in the direction away from the sheet bundle  100 . The motor  48  in  FIG. 2  causes the aligning plate  44  to move to the shutter  45  side and align the sheet bundle  100  on the sheet feeding tray  41 . 
     The sheet feeding roller  42 , the back roller  43 , and the shutter  45  return to the state in  FIG. 4A  to discharge the sheet A 2  at the top of the sheet bundle  100 . After that, the operations in  FIGS. 4B to 4D  and  FIGS. 4E to 4H  are repeated. However, the number of sheets retracted by the back roller  43  is reduced by one from the case described above and only the sheet A 3  is retracted. 
     The sheet B 2  is discharged and the sheet B 3  is retracted and then the sheet C 2  is discharged and the sheet C 3  is retracted. The sheets A 3 , B 3 , and C 3  remain in the sheet feeding tray  41 . The aligning plate  44  is moved to the shutter  45  side to align the sheets and returned to the original position. 
     In this state, the sheet feeding roller  42 , the back roller  43 , and the shutter  45  returns to the state in  FIG. 4A . However, since it is unnecessary to retract the sheets with the back roller  43  anymore, the sheet feeding roller  42  sequentially discharges the remaining sheets A 3 , B 3 , and C 3 . 
     The sheets discharged in the order of A 1 , B 1 , C 1  . . . A 3 , B 3 , and C 3  in this way are sent to the finisher  20 , subjected to punching processing by the punching mechanism  31  when necessary, further subjected to staple processing by the stapling mechanism  21 , and discharged to the sheet discharge tray  51 . 
     In the example described above, the sheet bundle  100 , in which the three pieces of each of the three types of sheets are stacked, is inserted in the sheet feeding tray  41 . When a user operates an operation unit  70  (described later with reference to  FIG. 5 ) provided in the inserter  40  to input “three types and three pieces”, collating processing is performed. In the case in which five pieces of each of four types of sheets are stacked and inserted in the sheet feeding tray  41 , when the user inputs “four types and five pieces”, the collating processing is performed five times for each of the four types of sheets. 
     The inserter  40  performs, on the basis of inputted information “n types and m pieces”, discharge, retraction, and alignment of sheets once, repeats the discharge, retraction, and alignment plural times, sequentially reduces the number of sheets to be retracted by one every time the discharge, retraction, and alignment is performed once, and performs only the discharge when the number of sheets to be retracted is reduced to zero. 
     A structure of a control system for the inserter  40  of the invention will be explained with reference to a block diagram in  FIG. 5 . 
     In  FIG. 5 , a control unit  60  has, other than a CPU, a ROM  61 , a RAM  62 , a counter  63 , and the like. The control unit  60  controls the inserter  40  in accordance with a control program stored in the ROM  61 . 
     The control unit  60  is connected to the operation unit  70  and controls operations of the inserter  40  in response to operation from the operation unit  70 . The RAM  62  is used for temporarily storing control data and used in arithmetic operation work at the time of control. Operations of the counter  63  will be described later. 
     The operation unit  70  includes, for example, plural keys or a display unit that also functions as a touch panel. The user operates the keys or the touch panel to input the types n and the pieces m of sheets to be inserted. 
     The inserter  40  has the motors  71  and  72  that drive to rotate the sheet feeding roller  42  and the back roller  43 . Further, the inserter  40  has driving units  73  and  74  that control to move the sheet feeding roller  42  and the back roller  43  in directions toward and away from the sheet bundle  100 , respectively. The control unit  60  controls these motors  71  and  72  and the driving units  73  and  74 . 
     The control unit  60  controls the driving of the motor  48  to control a position of the aligning plate  44  of the inserter  40 . Moreover, the control unit  60  controls opening and closing operations of the shutter  45 . 
     The control unit  60  is connected to a finisher control unit  75  that controls the finisher  20 . The finisher control unit  75  controls the stapling mechanism  21  and the like of the finisher  20 . The finisher control unit  75  and the control unit  60  transmit information to each other. The inserter  40  and the finisher  20  operate in cooperation with each other. 
     As the control of the finisher  20  by the finisher control unit  75 , there are stapling by the stapler  25 , conveyance of the sheets P to the stapler  25 , discharge of sheets after being stapled, and the like. 
       FIG. 6  is a flowchart for explaining the collating processing based on the control by the control unit  60 . The collating processing will be explained together with the operations in  FIGS. 4A to 4H . 
     Step S 1  in  FIG. 6  is a step in which the user operates the operation unit  70  to input the types n and the pieces m of sheets. The user inputs “n types and m pieces”. In the example in  FIGS. 4A to 4H , the user inputs n=3 and m=3. 
     Step S 2  is a step of aligning the sheet bundle  100  stored in the sheet feeding tray  41  with the aligning plate  44 . The next step S 3  is a step of discharging one sheet at the top of the sheet feeding tray  41  with the sheet feeding roller  42 . The step is equivalent to  FIG. 4A . 
     In step S 4 , the control unit  60  determines whether (m−1)=0. When (m−1) is not 0, in the next step S 5 , the control unit  60  retracts (m−1) sheets with the back roller  43 . In the case of m=3, the control unit  60  retracts two sheets. This step is equivalent to  FIGS. 4B and 4C . 
     In the next step S 6 , the control unit  60  increments a value of the counter  63  by 1. In step S 7 , the control unit  60  determines whether a value of the counter  63  is n. An initial value of the counter  63  is 0 and counted up by +1 every time the operation from steps S 3  to S 5  is performed. Therefore, according to the loop from step S 3  to step S 7 , the control unit  60  repeats the operation for discharging one sheet and retracting (m−1) sheets until the value of the counter  63  reaches n. This operation is equivalent to the operation from  FIGS. 4A to 4G . 
     When the value of the counter  63  reaches n in step S 7 , the control unit  60  shifts to step S 8 . The value of the counter  63  is reset and returns to 0. In the next step S 9 , the control unit  60  changes the value m to m−1. When an input value is 3, m is changed to 2. 
     In the next step S 10 , the control unit  60  determines whether m=0. Unless m≠0, the control unit  60  returns to step S 2  and performs the alignment processing. This operation is equivalent to  FIG. 4H . 
     In step S 3 , the control unit  60  discharges one sheet at the top of the sheet feeding tray  41 . In step S 4 , the control unit  60  determines whether (m−1)=0. When (m−1) is not 0, the control unit  60  shifts to the next step S 5  and retracts (m−1) sheets with the back roller  43 . Since the value m is changed to 2, in step S 5 , the control unit retracts one sheet. 
     The control unit  60  repeats the operation from steps S 3  to S 5  (for discharging one sheet and retracting one sheet) n times. When the value of the counter  63  reaches n in step S 6 , the control unit  60  shifts to step S 8  through step S 7 . The value of the counter  63  is reset and returns to 0. In the next step S 9 , the control unit  60  changes the value m to m−1. In this case, the value m further decreases by 1 to 1. 
     In the next step S 10 , since m≠0, the control unit  60  returns to step S 2  and performs the alignment processing again. In step S 3 , the control unit  60  discharges one sheet at the top of the sheet feeding tray  41 . 
     In step S 4 , the control unit  60  determines whether (m−1)=0. In this case, since (m−1)=0, the step S 5  is detoured and the retracting processing is not performed. In this case, the control unit  60  returns to step S 3  through the next steps S 6  and S 7  and repeats discharge of one sheet n times. 
     When the value of the counter reaches n in step S 6 , the control unit  60  shifts from step S 7  to step S 8 . The value of the counter  63  is reset and returns to 0. In the next step S 9 , the control unit  60  changes the value m to m−1. Therefore, the value m changed is 0. In step S 10 , the control unit  60  determined that m=0, shifts to step S 1 , and finishes the collating processing. 
     In this way, in the invention, when the sheet types n and the pieces m are inputted, the inserter  40  can automatically execute the collating processing. 
     The invention is not limited to the above explanation. Various modifications are possible without departing from the scope of claims. For example, as the finisher  20 , a saddle stitcher may be provided other than the stapling mechanism  21 . The saddle stitcher is an apparatus that bundles plural sheets supplied from the image forming apparatus  10  or plural sheets collated by the inserter  40  and folds the sheet bundle in two. 
     Although exemplary embodiments of the present invention have been shown and described, it will be apparent to those having ordinary skill in the art that a number of changes, modifications, or alterations to the invention as described herein may be made, none of which depart from the spirit of the present invention. All such changes, modifications, and alterations should therefore be seen as within the scope of the present invention.