Abstract:
Sheet post processing apparatus is disclosed in a compact form for receiving from an image forming machine successive sheets of printed material and performing post processing thereto, by feeding sheets into the apparatus at the output speed of the image forming machine, by stopping the leading edge of the sheets by feed rolls, performing a first post process on the sheet, upstream of the feed rolls, then feeding the processed sheet, by said feed rolls, at a higher speed by either a bypass path to a receiver or through a divergent path by a diverter to an inclined tray beneath the first processor for performance of a different post process and then from the inclined tray to a stacker by an additional output feed associated with the inclined tray.

Description:
BACKGROUND OF THE INVENTION 
     This invention regards a post processor that receives the sheets, onto which the image has already been recorded and which are discharged from image formation machines, such as printers, copiers, facsimile machines, and printing presses, and fed into the post processor, and that discharge the sheets after the necessary processing inside. 
     There have been, in the prior art, post processors that take the sheets onto which the image has already been recorded and which are discharged from the image formation machines such as printers and copiers and that discharge the sheets after the necessary processing such as sorting, inverting and punching and/or binding inside the post processor. 
     By incorporating a perforator or punch into the post processor, sheets can be perforated or punched. In order to do so, the post processor takes sheets in completely and stops them, and the perforator is placed where its perforation point meets the stopped sheet. However, since this structure requires a large space for taking and stopping the sheets, the size of the post processor may be enlarged. 
     On the other hand, if the post processor stops sheets before completely taking them inside, that is, to stop them while the image formation machine holds the latter half of the sheets, the size of the post processor can be minimized. However, in that case, since the control of the image formation machine needs to be changed to stop the sheets, the cost of initializing a post processor increases and it cannot be used for the existing image formation machines. 
     The post processor with a sheet inverting function can rotate sheets half way without damaging them. Upon such basic performance as a premise, it is desirable for the post processor to be very compact, not to require too much installation space and to maintain low cost. 
     Therefore, the post processor conventionally receives the sheets discharged from the image formation machine at the specified speed and discharges the sheets after the processing such as binding. This requires the processing capability with the speed not to disturb the sheet output timing of the image formation machine. 
     In order to do so, the transporting speed of the sheets inside of the post processor is set up to be higher than the speed of the image formation machine to create necessary processing time. However, since the sheet transporting structure in the post processor is typically designed to have several feed rollers placed at intervals that are shorter than the length of the sheets, the transporting speed of all sending rollers needs to be generalized. Therefore, it has been considered difficult to set up the transporting speed in the post processor higher than the sheet infeed speed of the image formation machine. 
     SUMMARY OF THE INVENTION 
     In view of the above, an object of the present invention is to provide a post processor that is compact and inexpensive while being equipped with a post processing function and that can be installed in conjunction with the existing image formation machines. 
     In order to achieve the above objective, this invention provides the post processor for an image formation machine that receives the sheets discharged from the image formation machine with infeed means and which discharges them after the necessary processing inside, wherein gate means to stop the leading edge of moving sheets in the middle of the sheet feed path, and that locates the automatic punch to punch holes in the specified position close to the front edge of the temporarily stopped sheets, and has a free space to enable the sheets to bend in front of the automatic punch. 
     The above post processor stops the front end of the sheets by the gate means and punches the sheets by the punch means while the image formation machine continues to feed sheets regardless of the functions of the post processor. The latter half of the sheet is sent toward the post processor even during the punching or other post processing. Therefore, the middle portion of the sheet bends in a loop and the sheet escapes into a free space since only the front end of the sheet is stopped by the gate means during the punching process. 
     Then, the post processor restarts feeding sheets after the completion of the punching process. 
     The feed rollers can be established in the middle of the sheet feed path and can be used as the aforementioned gate means by turning on and off the feed rollers. By doing so, it is cost effective because the gate means does not have to be separately provided. 
     The above feed rollers should be structured with two driving rollers facing each other. If the feed rollers are formed by two driving rollers like this, the resistance increases while the sending rollers stop, and the rollers become less likely to idle when the sheets contact the stopped rollers causing the sheets to stop at a certain position. 
     In order to achieve the above purpose, this invention provides a post processor for an image formation machine that has the feed path to take the sheets discharged from the image formation machine at the lead edge, to pass them through the machine, and to discharge them from the output from the post processor. 
     An inclined tray is located in the area directly underneath the feed path to incline the leading edge of the sheets downwardly to a sheet stopper on the lower end of the tray, a sheet transporting means to discharge the sheets placed on the inclined tray to an output portion of the post processor, a divergent feed path to feed the sheets from the middle of the aforementioned feed path onto the inclined tray, and a diverter located at the connection of the aforementioned feed path and the diverging path to alternatively switch the flow path to the output path or the diverging path, and that sets up the angle of the sheet and the higher side of the inclined tray to be acute when the sheets sent from the aforementioned diverging path move from the higher side to the lower side of the tray by being guided by the inclination of the inclined tray and stop when they hit the sheet stopper. 
     The above post processor receives the sheets discharged from the image formation machine at the lead end, passes them through the machine and discharges them from the output when the diverter opens the bypass path. On the other hand, when the diverter opens the diverging path, the sheets discharged from the image formation machine enter into the infeed path and flow onto the inclined tray from the bypass path through the diverging path. Since the angle of the sheet and the higher side of the inclined tray is set up to be acute when the sheets fed from the diverging path touch the inclined tray, the sheets entering into the inclined tray from the diverging path flow naturally from the higher end to the lower end along the inclination of the inclined tray and stop when they hit the sheet stopper. The sheets are reversed or inverted at this stage. Then, the sheet transporting means activates to push back and discharge the sheets placed on the top of the inclined tray. 
     The diverging feed means should be formed to force the sheets out toward the inclined tray in the aforementioned diverging path and to let the front end of the sheets reach the sheet stopper of the inclined tray before the diverging feed means releases the rear end of the sheets. By doing so, the front end of the sheets accurately reaches at the sheet stopper at high speed and the edges of the sheets can be aligned nicely. In a natural dropping method, first it takes time for the sheets to reach the sheet stopper and to stabilize themselves, and the sheets may stop in the middle of the process and the lead edges do not match. 
     A runner should be incorporated into a part of the diverging feed means and kick out the rear of the sheets onto the inclined tray. By doing so, high speed processing can be done without letting the trailing end of the sheet touch the leading end of the following sheet. 
     The punch should be located in front of the aforementioned diverter and enables punching the sheets between the infeed portion of the paper path and the diverter. By doing so, the punch can perforate both the sheets that passes through the feed path and the sheets that are supplied to the inclined tray in an inverted condition. 
     A cut off portion can be formed in a part of the aforementioned inclined tray and a stapler can be established to fit the cut off portion. By doing so, the sheets placed on the inclined tray according to the page number by inverting them on the tray can be bound by the stapler. 
     A tray guide should be formed above the aforementioned inclined tray and a deformed portion should be formed in either or both the inclined tray and/or the tray guide to correspond to the cut off portion. Thus, the gap between them becomes narrower by focusing around the cut off portion. By doing so, the stapler can easily bind the sheets because the thickness of a batch of sheets is tightened and reduced by the deformed portions. Since the deformed portions are partial and the resistance to the sheet decreases, the sheets can be inserted into or discharged from the deformed portions smoothly. 
     The post processor has the one way clutch mechanism associated with the infeed rollers to feed the sheets almost at the same speed as the output speed of the image formation machine. High speed rollers located behind the infeed rollers which have a sheet feeding speed higher than that of the aforementioned infeed rollers, and to cause the infeed rollers to move along with the sheets when the transporting speed of the sheet surpasses the infeed speed of the infeed rollers occurs. 
     In the aforementioned post processor, the sheets sent by the infeed rollers are put between the high speed rollers and forcefully pulled in when the sheets reach the high speed rollers. On the other hand, since the infeed rollers are equipped with the one way clutch mechanism, the transporting speed of the sheets that are fed by the high speed rollers surpasses the sending speed of the infeed rollers occurs, and the infeed rollers change speed to move along with the sheets. 
     The structure of the high speed rollers should have two power rollers facing each other. By doing so, the high speed rollers can send the sheet assuredly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a vertical section of the post processor; 
     FIG. 2 is a partial perspective of the post processor; 
     FIG. 3 is an enlarged section indicating the main portion of the feed path and a diverging path; 
     FIG. 4 is an enlarged section indicating the main portion of the diverging path and an inclined tray; 
     FIG. 5 is a perspective of the sheet transporting device below the inclined tray; 
     FIG. 6 is an X—X line section of FIG. 4; 
     FIG. 7 is a perspective of the inclined tray; 
     FIG. 8 is an exploded perspective indicating the tray guide and the feed rollers; and 
     FIG. 9 is an enlarged section of the main portion of the infeed portion indicating another form of the free space. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The post processor  1  has an upper tray  3   a  and a lower tray  3   b  installed in parallel to the box-shaped body  2  as shown in FIG.  2 . The post processor  1  and trays are installed on the output side of the image formation machine M as indicated by a dotted line in FIG.  1 . The wheels  4  are installed on the bottom of the post processor  1  for moving, and the post processor can freely move to the extent that the wheels do not come off the rail  5  of the image formation machine M. The post processor  1  can be moved by the handle  6  provided in the front center of the aforementioned lower tray  3   b,  when collecting the later described punching wastes and removing the jammed sheets S. If the post processor  1  is moved by the handle  6  it can be balanced with pressure applied to the handle  6  even when the balance leans toward the tray due to the sheets placed on the tray. Therefore, the post processor  1  can be moved smoothly. 
     The post processor  1  has a safety switch  8 , which turns on when pushed by the pin  7  of the image formation machine M. When the post processor  1  is disconnected from the image formation machine M, the safety switch  8  opens and automatically turns off the power of the post processor  1 . By providing the safety switch  8 , there is no risk of being electrocuted when working on the post processor  1  disconnected from the image formation machine M in comparison to the structure that manually turns the power on and off. There is also no simple mistake of forgetting to turn on the power when the post processor  1  is connected to the image formation machine M. 
     The opening cover  1   a  is located on the top of the post processor  1  as indicated by the two dotted lines in FIG.  1 . The post processor  1  also has two support portions  9   a  and  9   b  for the upper tray  3   a  and the lower tray  3   b.    
     Next, the internal structure of the post processor  1  will be explained. The infeed portion  10  for the sheet S is provided on the side that the post processor  1  connects to the image formation machine M almost at the same height as the output portion  9   a  of the aforementioned tray  3   a.  A swinging infeed guide  12  is supported around the short shaft  11  (refer to FIG. 1) in the infeed portion  10 . The infeed guide  12  fits into the outlet M 1  of the image formation machine M and stabilizes itself by placing its own cam side  12   a  on the step M 2  of the aforementioned outlet M 1 . When the post processor  1  is disconnected from the image formation machine M, the infeed guide  12  loses its support and lowers the front end due to its own balance. 
     The paper path  13  is provided between the aforementioned infeed portion  10  and the output portion  9   a  on the top portion of the post processor  1 . The paper path  13  roughly consists of a set of upper and lower sheet guides  14  leading to the aforementioned infeed guide  12 , the first infeed rollers  15   a  and  15   b  in the middle of the sheet guides  14  and the second feed rollers  16   a  and  16   b  near the output portion  9   a.    
     The upper roller  15   a  of the aforementioned first infeed rollers  15   a  and  15   b  is a so-called free rotating roller. The lower roller  15   b  is the driving roller that rotates counter-clockwise along with the rotating shaft  17  in FIG.  1 . Both infeed rollers  15   a  and  15   b  transport the sheets S by putting the sheets S between them at the same speed as the sheet feed speed of the image formation machine M. The rotating shaft  17  of the aforementioned lower feed roller  15   b  has a known clutch mechanism that switches the feed roller  15   b  to both rotating and stopping conditions by disconnecting the transmission from the power source (not shown) when the clutch mechanism is activated. The clutch mechanism has a so-called one way structure that transmits the power in only one direction. If the reverse phenomenon that the transporting speed of the sheet S surpasses the feed speed of the infeed roller  15   b  occurs, the clutch mechanism switches the infeed roller  15   b  to move along with the sheet S. 
     The upper roller  16   a  of the feed rollers  16   a  and  16   b  is a free rotating roller. The lower roller  16   b  is the driving roller that rotates counter-clockwise around the rotating shaft  18  in FIG.  1 . Both feed rollers  16   a  and  16   b  transport the sheet S by putting the sheets S between them at the same speed as the sheet feed speed of the image formation machine M. The upper feed roller  16   a  is installed on the movable sheet guide  20  that can freely swing around the hinge  19 , th rough the spring arm  21 . Therefore, the upper feed roller  16   a  can be opened with the sheet guide  20  if the sheets are jammed in the paper path  13  (as shown in broken lines in FIG.  4 ). The handle  20   a  is installed on the front edge of the sheet guide  20  and the top of the handle  20   a  is pushed outside from the bottom of the aforementioned cover  1   a.  Therefore, the cover  1   a  can also be opened by lifting up the edge of the sheet guide  20  by the handle  20   a.    
     An inclined tray  23  is located in the area directly underneath the aforementioned paper path  13  through the later mentioned diverging path  22 . The inclined tray  23  inclines to lift the edge of the aforementioned output portion  9   b  to be higher, and the sheet stopper  24  is located on the lower edge end of the tray  23 . The inclination of the inclined tray  23  is such that the angle (refer to FIG. 1, hereinafter simply called the entering angle) of the sheet S and the higher side of the inclined tray  23  becomes acute when the sheet S sent from the later mentioned diverging path  22  touches the inclined tray  23 . 
     The inclined tray  23  receives the sheets S and slips them to the bottom. Several ribs  25  (FIG. 7) are provided on the top of the inclined tray  23  to reduce friction with the sheet S. A tray guide  26  is located above the inclined tray  23 , and several sheets S can be stored between the inclined tray  23  and the tray guide  26 . Several ribs  27  (FIG. 8) are also formed on the surface of the tray guide  26  to reduce friction with the sheet S. 
     The adjustment unit  29  (FIGS. 6 and 7) that aligns the stored sheets S by putting one side of them to the permanent standard wall  28  on the other side is located on the inclined tray  23 . The adjustment unit  29  consists of the L shaped sliding part  29   a  located on the opposite edge of the permanent standard wall  28  and the swinging arm  29   b  that moves the sliding part  29   a.  The sliding part  29   a  fits in the slit  23   a  formed on the inclined tray  23  and can slide straight back and forth directly across the feed direction of the sheet S. On the other hand, the swinging arm  29   b  swings back and forth within a certain range by the power source such as motors or solenoid (not shown). The sliding part  29   a  moves straight back and forth along with the swinging arm  29   b  between the solid line and the two dotted lines in FIG.  7 . The leaf spring style cushion  29   c  is provided at the connection of the sliding part  29   a  and the swinging arm  29   b  as indicated by the broken line in FIG.  6 . When the large pressure is applied to the sliding part  29   a,  the cushion  29   c  bends and prevents unnatural movements of the sliding part  29   a.    
     Sheet transport means  30  as shown in FIGS. 5 and 6 is installed on the lower side of the inclined tray  23 . The sheet transporting means  30  has the endless timing belt  31  that rotates along the bottom of the inclined tray  23  and the T-shaped pins  32  on the timing belt  31 . It pushes out the drive pins  32  along the driving belts  33  on the inclined tray  23  and only the pins  32  are extend out on the top of the inclined tray  23  by the rotation of the timing belt  31 . Two sets of the timing belts  31  and the driving belts  33  are located at transversely spaced intervals (FIG. 6) and two drive pins  32  push the sheet S placed on the top of the inclined tray  23  equally. 
     Two drive pins  32  are provided for each timing belt  31  and are pushed out on the top of the inclined tray  23  one by one in order to increase the efficiency of the timing belt  31  by eliminating unnatural movements. The drive pins  32  directly touch the edge of the sheet S and push it upwardly on tray  23 . Since the drive pins  32  also push out the sheet S by directly touching the edge of the sheet S, the function can be completed by locating the key portion of the upside down T shaped drive pins to face the sheet S. However, the reasons why the drive pins  32  are purposely shaped like a T are to improve the productivity by enabling the installation in either direction as well as to prevent from producing malfunctioned products due to operational mistakes. The timing belt  31  of the sheet transporting means  30  is merely an example. Chains and strings can be used instead, or the drive pins  32  can be driven by a linear motor. 
     The cut off portion  34  is provided on the corner of the sheet stopper  24  and on the inclined tray  23  as shown in FIGS. 6 and 7. The electric stapler  35  is installed on the body  2  at the side of the tray and fits in the cut portion  34 . Therefore, it will be seen that the sheet transporting means  30  moves a batch of the sheets S to the binding point of the stapler  35  and temporarily stops the sheets S. Since the stapler  35  can be located close to the center of the body  2  by doing this, it is effective to minimize the size of the post processor  1 . 
     The upwardly deformed portion  23   b  of tray  23  is formed around the cut off portion  34  of the inclined tray  23  as shown in FIG.  7 . The downwardly deformed portion  26   a  of the aforementioned tray guide  26  is formed in the opposite position from the portion  23   b  of the inclined tray  23 , as shown in FIG.  8 . The gap between the inclined tray  23  and the tray guide  26  is narrower than other portions because of portions  23   b  and  26   a  being closer together. The portions  23   b  and  26   a  do not have to be formed on both the inclined tray  23  and the tray guide  26 , but on either one of them. 
     The number  36  in FIGS. 6 and 7 denotes a sheet sensor located on the fixed wall  28 . It detects the sheet S by its signal and prevents the stapler  35  from activating when the sheets S are not properly positioned. The reference characters  37  and  38  are two sheet sensors located on the sheet stopper  24  and detect two paper sizes, which are the size of the sheet S indicated by two dotted lines S-L and S-A in FIG. 6 representing letter size and A4 sheet sizes, by matching each signal of both sensors  37  and  38 . The reference character  39  designates the home position sensor of the drive pin  32 . It detects the piece  32   a  (FIG. 6) provided on the drive pin  32  and stops it in the home position by controlling the timing belt  31  by its signal. Each of the aforementioned sensors  36 - 38  is an optical sensor in the operating form, but micro switches or lead switches can also be used. 
     The reference character  40  in FIG. 5 represents a support base for the sheet transporting means  30 . A pulley  41  for the timing belts  31  are installed in shafts  42 . Reference character  43  represents a tension for timing belt  31 . Reference character  44  is a driving motor for the timing belt  31 . 
     As shown in FIGS. 1,  3  and  4 , the sheet diverting path  22  is formed between the paper path  13  and the inclined tray  23 . This diverting path  22  consists of the upper half portion of the aforementioned tray guide  26  and the diverter feed means located across the tray guide  26  and the body  2 . The diverter feed means are the high speed rollers  45   a  and  45   b  installed on the tray guide  26  and the body  2 . The rollers  45   a  of the high speed rollers  45   a  and  45   b  are attached to the tray guide  26  (FIG. 8) and are free rotating rollers. The other rollers  45   b  are the power rollers that rotate counter-clockwise with the rotating shaft  46  in FIG.  4 . Both high speed rollers  45   a  and  45   b  put the sheet S between them and transport them at higher speed (say, approximately twice as high in an operating mode) than the sheet feeding speed of the aforementioned feed rollers  15   a  and  15   b  (= the sheet feed speed of the image formation machine M). The high speed roller  45   a  attached to the tray guide  26  is installed on the same type of the spring arm that is used to install the aforementioned feed roller  16   a  and touches the high speed roller  45   b  by a specified pressure. 
     The installation positions of the high speed rollers  45   a  and  45   b  in the diverting path  22  is set up so that the distance between the connection of the high speed rollers  45   a  and  45   b  and the sheet stopper  24  of the inclined tray  23  is shorter than the length of the sheet. Therefore, when the front end of the sheet S reaches the sheet stopper  24 , the rear end of the sheet S is still remained in the high speed rollers  45   a  and  45   b.  Therefore, the high speed rollers  45   a  and  45   b  continue to feed out the rear end of the sheet S as they bend it, the resilient ribs of the later mentioned runner  47  push the trailing end of the sheet further, and the front end of the sheet S is caused to touch the sheet stopper  24  (FIG.  4 ). 
     The runner  47  with several resilient ribs is permanently installed around the rotating shaft  46  of the high speed roller  45   b  as shown in the FIGS. 4 and 8. The ribs of the runner  47  are elastic and bend easily when they touch the surface of the sheet as indicated by a broken line in the FIG.  4 . The runner  47  always rotates with the rotating shaft  46  and drives the rear end of the sheet S toward the top of the tray  23  in the moment that the rear end of the sheet S comes out of the high speed rollers  45   a  and  45   b  (as shown in broken lines in FIG.  4 ). 
     A pivoted diverter or gate  48  is located in the middle of the aforementioned paper path  13  between the infeed rollers  15   a  and  15   b  and the bypass rollers  16   a  and  16   b.  This diverter  48  is connected to solenoid (not shown) by a shaft  49 . It opens the path of the paper path  13  by lowering its edge when solenoid is magnetized as indicated by a solid line in FIG.  3 . It opens the flow path of the diverging path  22  by lifting its edge when solenoid is demagnetized as indicated by a broken line in FIG.  3 . Switching of paper paths by the diverter  48  is an alternative. The switch gate  48  closes the diverter path  22  when the paper path  13  is opened, and on the contrary, closes the paper path  13  when the diverter path  22  is opened. 
     A punch  50  is disposed in the paper path  13  in advance of the switch gate  48 . The punch  50  is publicly known to move the punch blade  54  attached to the cam follower  53  up and down by the eccentric cam attached to the rotating shaft  51 . The aforementioned infeed rollers  15   a  and  15   b  function to be the gate means to stop the front end of the sheet S when the punch  50  is activated, that is to stop feeding the sheet S by stopping the rotation of the infeed rollers  15   a  and  15   b  when the punch  50  is activated. For example, a shutter type part that opens and closes the paper path  13  can be installed in the middle of the paper path  13  instead of using the infeed rollers  15   a  and  15   b  as a gate means. However, in this case, since the gate means is separately installed, it becomes a factor of the higher cost. In other words, the punch  50  provided above with the infeed rollers  15   a  and  15   b,  stop the sheet S by stopping the infeed rollers  15   a  and  15   b  and the sheets S are punched by activating the punch  50  in that condition. Therefore, the sheet stopper for the punch  50  does not need to be installed separately, this way the low cost can be maintained. 
     As seen in FIG. 9, in relation to the punch  50 , a free space  55  between guides  12  that enables to bend the sheets S is in front of the punch  50 , which is between the punch  50  and the outlet M 1  of the image formation machine M. The free space  55  can be formed, for example, between the infeed guide  14  and the infeed guide  12  as shown in FIG. 3 or between the infeed guide  12  and the outlet M 1  as shown in FIG. 9 or can also be formed by combining FIGS. 3 and 9 (not shown). The minimum size required for the free space  55  is determined based on how many pieces of the sheet S are sent from the image formation machine M when the front end of the sheet S is stopped during the operation of the punch  50  as mentioned later. 
     As seen in FIG. 3, an elastic synthetic resin board  56  is located in the free space  55  and the sheet S pushes and curves it when the sheet S bends with a big loop. By doing so, the bent sheet S does not wrinkle easily. 
     Also, as seen in FIG. 3, a box  57  for punching waste of the punch  50  is installed under the paper, path  13  next to the tray guide  26 . 
     As mentioned earlier, the upper tray  3   a  and the lower tray  3   b  that receive the sheets S are located in the output portions  9   a  and  9   b.  The upper tray  3   a  can be detached from the body  2 , but it does not move when it is installed in a permanent position. On the contrary, the lower tray  3   b  can be detached from the body  2  and shifts its position up and down according to the number of sheets placed on it. That is, the lower tray  3   b  is connected to the elevator means  58  as seen in FIG.  2 . The elevator means consists of the motor  58   a,  the gears  58   b,  the screw shaft  58   c  and the elevating arm  58   d  as shown in FIG.  2 . It detects the weight of the sheets S placed on the lower tray  3   b  by a sensor (not shown) and moves up and down to maintain a constant level of the sheets S by controlling the aforementioned motor  58   a  by its signal. The sensors  58   e  and  58   f  are provided in the elevator device  58  and detect the upper and lower thresholds of the elevating arm  58   d.    
     The operation of the post processor  1  is as follows. As mentioned earlier, the post processor  1  is installed on the output side of the image formation machine M and turns on when the pin  7  pushes the safety switch  8  of the image formation machine M. 
     The sheets S are discharged from the image formation machine M into paper path  13 . Since the switch gate  48  usually closes the feed path by lifting its front end as indicated by a two dotted line in FIG. 3, it lowers the front edge of the switch gate  48  by magnetizing solenoid as indicated by a solid line in the same figure, and it opens the paper path  13 . Then, the sheets S discharged from the image formation machine M will be discharged onto the upper tray  3   a  after going into the infeed rollers  15   a  and  15   b  and then to the feed rollers  16   a  and  16   b  as shown by the arrow Y in FIG.  3 . 
     To perforate the sheet S, the perforator stops the infeed roller  15   b  first and then stops the front end of the sheet S discharged from the image formation machine M. In this condition, if the punch moves the puncher blade  54  up and down with one rotation of the eccentric cam  52 , it punches holes on the edge of the sheet S. On the other hand, the latter half of the sheet S continues to be fed from the image formation machine M, while the front of the sheet is punched by activating the puncher  50 , but the center of the sheet S bends to the extent that the length of the sheets are fed during that period as indicated by a broken line in FIG.  3  and they move into the free space  55 . The punching application is completed before the sheet S fills the free space  55  and the infeed roller  15   b  rotates and sends the sheets S to the feed rollers  16   a  and  16   b.    
     Punching wastes drop into and are stored in the box  57  underneath the perforator  50 . Therefore, they need to be collected and disposed regularly. In that case, pull the post processor  1  by the handle  6  of the lower tray  3   b  and remove the box  57  by disconnecting the post processor  1  from the image formation machine M. 
     The diverter gate  48  normally opens the flow path of the diverter path  22  by lifting its front edge as indicated by a two dotted line in FIG.  3 . Therefore, the sheets S discharged from the image formation machine M are sent to the infeed rollers  15   a  and  15   b  and then to the high speed rollers  45   a  and  45   b  through the diverter gate  48  as indicated by the arrow Z in FIG.  3 . As mentioned earlier, the speed of the high speed rollers  45   a  and  45   b  is set up to be higher than the sheet feeding speed of the infeed rollers  15   a  and  15   b.  The front end of the sheet S is immediately pulled in at high speed as soon as it is nipped between the high speed rollers  45   a  and  45   b.  At this point, the rear end of the sheet S is placed between the infeed rollers  15   a  and  15   b.  However, since the one-way clutch mechanism is installed between the infeed roller  15   b  and the power source, the infeed roller  15   b  automatically switches to be the free roller that moves along with the sheets S in the period that the transporting speed of the sheet S surpasses its own input speed. 
     If the infeed rollers  15   a  and  15   b  pull the sheet S almost at the same speed as the input speed of the image formation machine M, the sheet transporting speed of the high speed rollers  45   a  and  45   b  downstream from the infeed rollers  15   a  and  15   b  is set up to be higher than the speed of the infeed rollers, and the aforementioned one way clutch mechanism is incorporated into the infeed roller  15   b,  the sheets S that are synchronized and fed at low speed into the formation machine M can be processed at high speed inside of the post processor  1 . Of course, the speed of the feed rollers  16   a  and  16   b  in the paper path  13  can be set up to be higher than the speed of the infeed rollers  15   a  and  15   b.  In this case, the loss of time made by the punching operation can be recovered by transporting the sheets S at high speed. 
     When the divergent path to tray  23  is opened, the front end of the sheet S reaches inclined tray  23  naturally flows toward the sheet stopper  24  along the inclination of the inclined tray  23  because the entering angle of the sheet S and the inclined tray  23  is acute. At this stage, front and back of the sheet S are inverted. The front end of the sheet S is fed by the high speed rollers  45   a  and  45   b  and immediately reaches at the sheet stopper  24 . As mentioned earlier, since the installation positions of the high speed rollers  45   a  and  45   b  are located so that the distance between the connection of the high speed rollers  45   a  and  45   b  (a release point) and the sheet stopper  24  of the inclined tray  23  is shorter than the length of the sheet, the rear end of the sheet S is still remained in the high speed rollers  45   a  and  45   b  even when the front end of the sheet S reaches at the sheet stopper  24 . Therefore, the sheets S bend softly and come out of the high speed rollers  45   a  and  45   b,  as shown in FIG.  4 . Since the runner  47  is mounted around the rotating shaft  46  of the high speed roller  45   b  and rotates with the high speed roller  45   b,  the rear end of the sheet S is kicked out onto the inclined tray  23  in the moment that the rear end of the sheet S comes out of the high speed rollers  45   a  and  45   b  as indicated by a broken line in FIG.  4 . 
     Then, the timing belt  31  of the sheet transporting means  30  activates and the drive pin  32  pushes the sheets S along the driving line  33  of the inclined tray  23 . When the timing belt  31  rotates half way, the sheets S are discharged onto the lower tray  3   b  and stop when the drive pin  32  waits at a home position. If the sheets S are jammed in the diverter path  22  or on the inclined tray  23 , disconnect the post processor  1  can be disconnected from the image formation machine M by the handle  6  of the lower tray  3   b  first and pull the tray guide  26  by the pick up portion  26   b  after removing the box  57  for punching wastes. The jammed sheets S can be easily removed since the tray guide  26  rotates around the upper hinge  26 c (see FIGS. 1 and 8) and opens. 
     Binding several sheets will now be described. First, the sheets S are sent onto the inclined tray  23  one by one from the first page as mentioned earlier. In this case, the sheets S are continuously sent to be processed at high speed. Since the runner  47  kicks out the rear end of the sheets S discharged from the high speed rollers  45   a  and  45   b  onto the inclined tray  23  as mentioned earlier, the rear end of the sheet S and the front end of the following sheet S never touch each other. 
     Each time the sheet S is sent onto the inclined tray  23 , the jogging unit  29  activates once and the sliding part  29   a  moves back and forth once to move each sheet. When the number of the sheets increases, the gap between the portions  23   b  and  26   a  becomes narrower and it becomes difficult to send the sheet S. However, since the swelled portions  23   b  and  26   a  are partial and small, the resistance is relatively small. When the specified number of sheets are sent, the drive pins  32  of the sheet transporting means  30  are activated and transport a batch of the sheets S to the binding point of the stapler  35  and stops. Then, the stapler  35  is activated and binds the batch of the sheets S with metal staples. At this point, the batch of the sheets S is compressed by the portions  23   b  and  26   a,  it is easy to be stapled. 
     Then, the drive pins  32  of the sheet transporting means  30  are activated again and discharge the bound batch of the sheets S onto the lower tray  3   b.  The drive pins  32  are designed to transport the sheets S initially at high speed and to decrease the speed before discharging them onto the lower tray  3   b.  By doing so, the sheets S never jump out of the lower tray  3   b.  The lower tray  3   b  can move up and down as mentioned earlier. It descends when the sheets are placed on the tray and automatically ascends when the sheets S are removed from it. 
     It is needless to say that the punch  50  can perforate the edge of the sheet S even when several sheets S are stapled by being rotated. 
     Refilling of the metal staples in the stapler  35  should be done by disconnecting the post processor  1  from the image formation machine M. 
     In another form, this invention has a feature that both high speed rollers  45   a  and  45   b  are driving rollers. That is, fix a gear (not shown) to the edge of the rotating shaft by stabilizing the full high speed roller  45   a  to one rotating shaft. On the other hand, also fix a gear (not shown) to the edge of the rotating shaft  46  of the other high speed roller  45   b.  Both gears rotate the high speed roller  45   a  in the opposite direction from the high speed roller  45   b  at the same rotation speed. When the high speed rollers  45   a  and  45   b  grips the sheet S between them as mentioned earlier, they may slip at first due to the resistance because the rear end of the sheet S is remained in the infeed rollers  15   a  and  15   b.  However, if both high speed rollers  45   a  and  45   b  are driving rollers like in this operation form  2 , the high speed rollers  45   a  and  45   b  can send the sheet accurately and pull them by the strong force. 
     By setting up both high speed rollers  45   a  and  45   b  to be driving rollers, the incidents can be prevented when the post processor  1  is not used for a long period of time. That is, since the high speed rollers  45   a  and  45   b  have rubber-like elastic structures, the contacting parts become flat and their shapes become distorted causing the sheet infeed to be unstable when the high speed rollers  45   a  and  45   b  are not used for a long period of time while the strong pressure is applied to them. If both high speed rollers  45   a  and  45   b  are driving rollers, the gap between both high speed rollers becomes narrower than the thickness of the sheets S and both high speed rollers do not touch. If both high speed rollers do not touch, their shapes will not be distorted even when they are not used for a long period of time. However, the thickness of the sheets S is actually extremely thin, it is difficult for the high speed rollers  45   a  and  45   b  not to touch and actually they touch slightly. If they only touch slightly, the degree of shape distortion is small enough not to cause any operational problems. 
     Both infeed rollers  15   a  and  15   b  should also be driving rollers that consists of the gate means. That is, gears (not shown) are fixed to the edge of the rotating shaft of the upper roller  15   a  and the rotating shaft  17  of the lower roller  15   b  and both gears rotate the upper roller  15   a  in the opposite direction from the lower roller  15   b  at the same rotation speed. The difference between the driving rollers and the free rollers is that when the sheets S collide tangentially while rollers are stopping, the free rollers slightly rotate when pushed by the sheets S, but the driving rollers do not rotate when pushed by the sheets S because they are connected to the driving source and have resistance. Therefore, by setting up both infeed rollers  15   a  and  15   b  to be driving rollers, they can close the gate more strongly, and as a result, the stop position of the sheet S becomes constant and therefore the punching accuracy improves. Although the rotating shaft  17  of the lower infeed roller  15   b  has a clutch mechanism as mentioned earlier, the clutch function of the rotating shaft  17  directly applies to the upper infeed roller  15   a.    
     By setting up both infeed rollers  15   a  and  15   b  to be driving rollers, the incidents can be prevented when the post processor  1  is not used for a long period of time like the aforementioned high speed rollers  45   a  and  45   b.    
     As mentioned earlier, since the post processor of this invention locates the high speed rollers behind the infeed rollers and also provides the one way structure clutch mechanism in the infeed rollers, the high speed rollers can easily transport the sheets, which were taken in at the transporting speed of the image formation machine, at high speed. Therefore, it can conduct the specified post processing without disturbing the sheet output timing of the image formation machine. 
     As mentioned in the application item  2 , if the high speed rollers are provided with two driving rollers facing each other, they can send sheets more accurately and their shapes do not change when they are left unused for a long period of time because they do not need to firmly touch each other.