Abstract:
A waiting tray is provided in a sheet-conveying path and holds sheets if the sheets need to be post-processed. A processing tray receives sheets conveyed from the waiting tray. It may receive sheets conveyed through the sheet-conveying path and coming not via the waiting tray, before the sheets are post-processed. A conveying mechanism is provided, which causes the sheets to fall, due to gravity, from the waiting tray onto a processing tray. A sheet-aligning mechanism aligns the sheets on the processing tray, at their transverse edges and longitudinal edges. On the processing tray, the sheets are post-processed, forming a bundle. The conveying mechanism conveys the bundle of sheets to a storage tray. A control mechanism controls the speed of sheet-feeding rollers provided at upstream of the waiting tray, thereby to the place sheets at a preset position on the waiting tray.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2004-282209, filed Sep. 28, 2004, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a sheet post-process apparatus, such as a finisher, which is designed for installation at the outlet side of a multi-function periperal (MFP).  
         [0004]     2. Description of the Related Art  
         [0005]     An apparatus called “finisher” is known, which receives printed sheets supplied from an MFP and staples them together. In the finisher, the sheets supplied from the MFP are sequentially conveyed to a tray and stapled by a stapler, forming a bundle of sheets. The bundle of sheets is ejected from the apparatus onto a storage tray.  
         [0006]     Jpn. Pat. Appln. KOKAI Publication No. 6-99070 discloses a finisher. This finisher performs a post-process on sheets. In the post-process, a stapler staples sheets. To process the sheets at the same rate as the MFP processes them, it is necessary to reduce the speed at which sheets are conveyed in the finisher. The finisher therefore has a long sheet-conveying path.  
         [0007]     Having a long sheet-conveying path, the finisher cannot be as small as desired.  
         [0008]     Jpn. Pat. Appln. KOKAI Publication No. 5-16569 discloses a technique of detecting both of the leading edge and trailing edge of a sheet, thereby to control the speed of conveying the sheet.  
       BRIEF SUMMARY OF THE INVENTION  
       [0009]     An object of the present invention is to provide a sheet post-process apparatus in which each sheet conveyed to the waiting tray can be placed at a preset position on the waiting tray.  
         [0010]     A sheet post-process apparatus according to this invention comprises: a plurality of rollers which receive sheets from an MFP and convey the sheets forward; a waiting tray which is provided in a conveying path and holds the sheets conveyed from the rollers when the sheets need to be post-processed; a control mechanism which controls a speed of sheet-feeding rollers included in the plurality of rollers and provided at upstream of the waiting tray, thereby to place sheets at a preset position on the waiting tray; a processing tray which holds the sheets conveyed from the waiting tray and the sheets conveyed via the conveying path without being conveyed to the waiting tray, before the sheets are post-processed; a conveying mechanism which causes the sheets to fall, due to gravity, from the waiting tray onto the processing tray; a sheet-aligning mechanism which aligns the sheets with one another on the processing tray, at transverse edge and longitudinal edge, thereby forming a bundle of sheets; a post-process mechanism which performs a post-process on the bundle of sheets on the processing tray; sheet-conveying means for conveying the bundle of sheets from the processing tray; and a storage tray which holds the bundle of sheets conveyed from the processing tray.  
         [0011]     Preferably, the control mechanism may comprises: first detecting means for detecting sheet information supplied from the MFP; second detecting means provided between the first detecting means and the waiting tray, for detecting a leading edge of a sheet; and control means for generating a control signal for controlling a speed of the sheet-feeding rollers, from the sheet information and the leading edge detected by the first and second detecting means, respectively.  
         [0012]     It is desired that the control mechanism should control the speed of sheet-feeding rollers in accordance with job information supplied from the MFP.  
         [0013]     Preferably, the control mechanism may control the speed of the sheet-feeding rollers in accordance with information representing a size of the sheets.  
         [0014]     Preferably, the control mechanism may control the speed of the sheet-feeding rollers in accordance with information representing a thickness of the sheets.  
         [0015]     In the apparatus, the waiting tray holds sheets to be post-processed. The conveying mechanism causes these sheets to fall, due to gravity, onto the processing tray. Hence, it suffices to provide a sheet-waiting section that is just as long as the waiting tray. This renders the sheet post-process apparatus small.  
         [0016]     The sheet-feeding rollers provided immediately before the waiting tray rotate at the same high speed as the sheet-conveying rollers. If the sheets are ejected, they may stagger in the direction they are conveyed, depending upon their condition. This problem can be solved, because the control mechanism controls the speed of sheet-feeding rollers included in the plurality of rollers and provided at upstream of the waiting tray, thereby placing the sheets at a preset position on the waiting tray. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0017]      FIG. 1  is a perspective view of a post-process apparatus according to this invention;  
         [0018]      FIG. 2  is a top view of the post-process apparatus according to the invention;  
         [0019]      FIG. 3  is a perspective view illustrating how the waiting tray of the post-process apparatus performs its function;  
         [0020]      FIG. 4  is a perspective view depicting the sheet-bundle conveying mechanism provided in the post-process apparatus, and explaining how sheets are aligned at longitudinal edges in the post-process apparatus;  
         [0021]      FIG. 5  is a perspective view showing the mechanism for aligning sheets at their transverse edges;  
         [0022]      FIG. 6  is a perspective view illustrating how the stapler provided in the post-process apparatus performs its function;  
         [0023]      FIG. 7  is a sectional view of the post-process apparatus, showing how the first sheet moves from the input rollers to the sheet-feeding roller;  
         [0024]      FIG. 8  is a sectional view of the apparatus, explaining how the first sheet moves from the sheet-feeding rollers to the waiting tray;  
         [0025]      FIG. 9  is a sectional view of the apparatus, explaining how the second sheet moves from the sheet-feeding rollers to the waiting tray;  
         [0026]      FIG. 10  is a sectional view of the post-process apparatus, showing how the waiting-tray rollers operate;  
         [0027]      FIG. 11  is another sectional view of the apparatus, illustrating how the waiting-tray rollers operate;  
         [0028]      FIG. 12  is a sectional view of the apparatus, explaining how an active drop is carried out;  
         [0029]      FIG. 13  is a sectional view of the apparatus, explaining how the third sheet is conveyed;  
         [0030]      FIG. 14  is a sectional view of the apparatus, illustrating how the stapler operates;  
         [0031]      FIG. 15  is a sectional view of the apparatus, explaining how a bundle of sheets moves between the processing tray and the storage tray;  
         [0032]      FIG. 16  is a sectional view of the apparatus, illustrating how sheets move from the waiting tray to the storage tray;  
         [0033]      FIG. 17  is a sectional view of the apparatus, explaining how the position of the storage tray is changed;  
         [0034]      FIG. 18  is a sectional view of the apparatus, explaining the speed control mechanism that controls the speeds at which the input rollers and sheet-feeding rollers are rotated; and  
         [0035]      FIG. 19  is a flowchart explaining how the speed control mechanism controls the speeds of rotation of the input rollers and sheet-feeding rollers. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0036]     An embodiment of this invention will be described, with reference to the accompanying drawings.  
         [0037]      FIG. 1  is a perspective view of a section of a sheet post-process apparatus according to this invention.  FIG. 2  is a top view of said section of the post-process apparatus. As  FIG. 1  shows, the post-process apparatus comprises a waiting tray  10 , a processing tray  12 , a stapler  14 , a first storage tray  16 , and a second storage tray  18 .  
         [0038]     The sheet post-process apparatus further comprises a pair of input rollers  22 , a pair of sheet-feeding rollers  24 , and an input-roller motor  26 . The input rollers  22  receive a sheet  20  supplied from an MFP and convey the sheet  20  to the sheet-feeding rollers  24 . The sheet-feeding rollers  24  convey the sheet  20  to the waiting tray  10 . The input-roller motor  26  drives the input rollers  22 .  
         [0039]     One of the input rollers  22  is an upper input roller  22   a , and the other input roller  22  is a lower input roller  22   b . Likewise, one of the sheet-feeding rollers  24  is an upper sheet-feeding roller, and the other sheet-feeding roller  24  is a lower sheet-feeding roller.  
         [0040]     The waiting tray  10  comprises two tray parts  10   a  and  10   b . The tray parts  10   a  and  10   b  can move from left to right, and vice versa. When the tray parts  10   a  and  10   b  take a closed position, the waiting tray  10  can receive sheets. Waiting-tray rollers  28 , a waiting-roller drive  30  and a waiting-roller motor  32  are provided. The waiting-tray rollers  28  align sheets on the tray parts  10   a  and  10   b  while both tray parts remain in the closed position. The waiting-tray rollers  28  can move up and down when they are driven and controlled by the waiting-roller drive  30 . The waiting-roller motor  32  rotates the waiting-tray rollers  28 .  
         [0041]     When the number of sheets  20  stacked on the waiting tray  10  reaches a prescribed value, a waiting-tray motor  34  drives the waiting-tray parts  10   a  and  10   b  to an opened position as is illustrated in  FIG. 3 . The sheets  20  fall onto the processing tray  12 , due to gravity. This event is known as “active drop.” 
         [0042]     The sheet post-process apparatus has a paper guide  36 , which guides sheets from the MFP to the waiting tray  10  and thence to the processing tray  12 . The paper guide  36  has a paper-pass ceiling.  
         [0043]     In the processing tray  12 , the sheets are aligned at the longitudinal edges and the transverse edges. The sheets are aligned at their longitudinal edges by a longitudinal-alignment mechanism  38  as is illustrated in  FIG. 4 . More precisely, an upper longitudinal-alignment motor  40  drives the upper longitudinal-alignment rollers  38   a  of the mechanism  38 , and a lower longitudinal-alignment motor  42  drives the lower longitudinal-alignment rollers  38   b  of the mechanism  38 . Driven by the motors  40  and  42 , the rollers  38   a  and  38   b  move the sheets until one longitudinal edge of every sheet abuts on a stopper  45 . Paddles  44  are provided to facilitate the longitudinal alignment. A paddle motor  46  drives the paddles  44 .  
         [0044]     The sheets are aligned at their transverse edges, too, as is illustrated in  FIG. 5 . More specifically, the transverse alignment is performed by a transverse-alignment mechanism  47  and a transverse-alignment motor  48 .  
         [0045]     When the number of sheets thus aligned in the processing tray  12  reaches the prescribed value, the stapler  14  starts operating. The stapler  14  is positioned as depicted in  FIG. 6  and controlled by a stapler-driving unit  49 .  
         [0046]     Controlled by the unit  49 , the stapler  14  staples the sheets together, forming a bundle of sheets. As shown in  FIG. 4 , a transport mechanism  50  transports the bundle of sheets to the first storage tray  16 . Either the first storage tray  16  or the second storage tray  18  is selected when a storage-tray driving unit  52  ( FIG. 2 ) moves the tray  16  or  18  to a predetermined upper position.  
         [0047]     How the post-process apparatus according to this invention operates will be explained with reference to FIGS.  7  to  17 .  
         [0048]     As  FIG. 7  shows, a sheet  20  conveyed from the MFP is moved from the input rollers  22  to the sheet-feeding rollers  24 , in the direction of the arrow.  
         [0049]     As is illustrated in  FIG. 8 , the sheet  20 , or the first sheet, is placed on the waiting tray  10 . Then, the waiting-tray rollers  28  move down, in the direction of the arrow, aligning the trailing edge of the first sheet  20  at the rear (i.e., upstream) end  60  of the waiting tray  10 .  
         [0050]     As  FIG. 9  depicts, the waiting-tray rollers  28  moves up to receive the second sheet  20   a.    
         [0051]     As  FIG. 10  shows, the second sheet  20  is conveyed to the waiting tray  10 . The waiting-tray rollers  28  move down, aligning the trailing edge of the second sheet  20   a  at the rear end  60  of the waiting tray  10 . Thus, a bundle  20   b  of two sheets  20  and  20   a  is formed in the waiting tray  10 .  
         [0052]     As  FIG. 11  shows, the waiting-tray rollers  28  move upwards. Then, the waiting-tray parts  10   a  and  10   b  move to the opened position as is illustrated in  FIG. 3 . The active drop is therefore performed as shown in  FIG. 12 . The bundle  20   b  is conveyed to the processing tray  12 .  
         [0053]     Thereafter, the third sheet  20   c  and some following sheets are conveyed from the sheet-feeding rollers  24  to the processing tray  12 , not through the waiting tray  10 . These sheets are laid, one after another, upon the bundle  20   b  of two sheets. A bundle  21 , which consists of the prescribed number of sheets, is formed on the processing tray  12 . As the sheets including the third sheet  20  are sequentially laid on the bundle  20   b , the longitudinal-alignment rollers  38  and the transverse-alignment mechanism  47  align the sheets at their longitudinal edges and transverse edges.  
         [0054]     The waiting tray  10  must be positioned so that its rear end  60  may lie downstream of the rear end (upstream-side) of the processing tray  12  when the sheets are laid on the bundle  20   b . As shown in  FIG. 13 , the rear end  60  of the waiting tray  10  is therefore spaced from the rear end  62  of the processing tray  12 , by distance L, in the transverse direction. This enables the bundle  20   b  to fall smoothly from the waiting tray  10  onto the processing tray  12 . This also makes it easy for both alignment mechanisms  38  and  47  to align sheets. Thus, jamming of sheets can be prevented.  
         [0055]     It is desired that the waiting tray  10  and the processing tray  12  be inclined, having their upstream ends at a lower position than their downstream ends. In other words, they should be so positioned that their rear ends  60  and  62  lie at the lowest position. If the trays  10  and  12  are so inclined, the sheets  20  are aligned, due to gravity, at the rear end  60  of the waiting tray  10 , and the bundle  20   b  can be aligned, due to gravity, at the rear end and  62  of the processing tray  12 .  
         [0056]     As seen from FIGS.  10  to  13 , the sheet post-process apparatus has the following three characterizing features: 
        (1) The waiting tray  10  extends longer in the sheet-conveying direction than the length of sheets  20 .     (2) The processing tray  12  extends shorter in the sheet-conveying direction than the length of sheets  20 .     (3) Because of the feature (2), any sheet  20  that has fallen from the waiting tray  10  onto the processing tray  12  is supported not only by the processing tray  12 , but also by the first storage tray  16 .        
 
         [0060]     These features (1), (2) and (3) reduce the size of the sheet post-process apparatus (i.e., finisher) in the sheet-conveying direction.  
         [0061]     As  FIG. 14  shows, the stapler  14  staples the bundle  21  of sheets. Then, the transport mechanism  50  transports the bundle  21  to the storage tray  16  as illustrated in  FIG. 15 . Thus, the post-process ends.  
         [0062]     If the sheets need not undergo the post-process, they are not conveyed to the processing tray  12 . They are ejected from the waiting tray  10  onto the first storage tray  16  as shown in  FIGS. 16 and 17 . As  FIG. 16  shows, the sheets supplied from the MFP are sequentially conveyed to the first storage tray  16  via the input rollers  22 , sheet-feeding rollers  24  and waiting tray  10 . The waiting-tray rollers  28  move down, serving to convey sheets  20 . As depicted in  FIG. 17 , the storage-tray driving unit  52  lifts the first storage tray  16  a little and receives the sheets coming from the waiting tray  10 .  
         [0063]     The post-process apparatus has a mechanism that controls the speeds of rotation of the input rollers  22  and sheet-feeding rollers  24 . This mechanism will be described with reference to  FIG. 18   
         [0064]     As  FIG. 18  depicts, a entrance sensor  70  is provided at the nip between the input rollers  22 , to which a sheet  20  is conveyed, and a sheet sensor  72  is provided at upstream of the sheet-feeding rollers  24 . The entrance sensor  70  detects the leading edge and trailing edge of the sheet  20 . The sheet sensor  72  detects the leading edge of the sheet  20 . The output signals of the entrance sensor  70  and sheet sensor  72  are supplied to a speed-controlling unit  74 . The unit  74  generates a control signal  76  from the output signals of the sensors  70  and  72 . The control signal  76  is supplied to a sheet-feeding roller motor (not shown). Controlled by the signal  76 , the motor drives the sheet-feeding rollers  24  at a specific speed.  
         [0065]     How the speed of rotation of the sheet-feeding rollers  24  is controlled will be explained, with reference to the flowchart of  FIG. 19 .  
         [0066]     When a sheet  20  is conveyed from the MFP to the post-process apparatus, the input rollers  22  and the sheet-feeding rollers  24  are rotated at the same speed V 1 . In Step  100 , the entrance sensor  70  detects the leading edge of the sheet  20  conveyed to the post-process apparatus, generating a signal. In Step  102 , the entrance sensor  70  detects the trailing edge of the sheet  20 , generating a signal. The two signals thus generated are supplied to the speed-controlling unit  74 . In Step  104 , the speed-controlling unit  74  finds the size of the sheet  20  from the speed V 1  of the input rollers  22 .  
         [0067]     In Step  106 , the speed-controlling unit  74  determines whether the sheet  20  has the A4 size or a smaller size. If YES, the operation goes to Step  108 . In Step  108 , the sheet sensor  72  detects the leading edge, the speed-controlling unit  74  generates a control signal  76 . In Step  110 , the signal  76  is supplied to the sheet-feeding roller motor to decrease the speed of the motor from V 1  to V 2 . V 1 ≧V 2 , but V 1 =V 2  if the sheet  20  is an A4-size sheet.  
         [0068]     In Step  112 , the speed-controlling unit  74  changes the speed of the sheet-feeding rollers  24  back to V 1  when the sheet  20  is conveyed to the waiting tray  10 .  
         [0069]     If NO in Step  106 , or if the sheet  20  has a size larger than the A4 size, the operation goes to Step  114 . In Step  114 , the sheet sensor  72  detects the leading edge of the sheet  20 . Nevertheless, the speed of the sheet-feeding rollers  24  is maintained at V 1  in Step  116 .  
         [0070]     In the embodiment, the speed of the sheet-feeding rollers  24  is controlled in accordance with the data acquired within the post-process apparatus. Instead, the speeds of conveying sheets of different sizes can be controlled in accordance with the job information generated in the MFP.  
         [0071]     Thus, the speed of the sheet-feeding rollers  24  is controlled on the basis of the data about the sheet  20 . This renders the post-process apparatus compatible with various types of MFPs. For the same reason, the post-process apparatus can work together with any MFP even if the MFP is altered in specification.  
         [0072]     Furthermore, the post-process apparatus can perform a post-process on sheets, regardless of the thickness of the sheets.  
         [0073]     One embodiment of the invention has been described. The invention is not limited to the embodiment, nevertheless. The components described above may be replaced with other components that are identical in function.