Abstract:
An apparatus and method for processing paper ejected from an image forming device includes the use of a plurality of bins for sorting the paper ejected from the image forming device into packets and for housing the packets. A tray for stacking the packets is provided, along with a packet conveying device for conveying the packets from the plurality of bins to the tray. A detection device is included for detecting the maximum amount of paper that can be stacked onto the tray. A control device is also included which performs a number of controlling functions such as halting the packet conveying device, counting the number of empty bins from which the packets have already been removed and transmitting the number to an image forming device controller, in addition to controlling the guidance of the paper subsequently ejected from the image forming device in the empty bins.

Description:
FIELD OF THE INVENTION 
     The invention generally relates to an apparatus and method for processing paper, and more particularly, to a paper processing apparatus and method that can sort and staple sheets of paper ejected from a copying machine or printer, on which images have been formed. 
     DESCRIPTION OF RELATED ART 
     In recent years, various types of sorters for image forming devices such as copying machines and printers have been proposed. These sorters sort sheets of paper on which images have been formed into multiple bins in proper page sequence and staple them together when necessary. 
     In order to handle a large amount of paper, a sorter of this type must be constructed such that it contains a large-capacity tray separate from the multiple bins, wherein packets of sheets (hereinafter termed “packets”) once sorted into the bins are transferred to the tray such that more sheets may be sorted into the emptied bins. A sorter of this type is conventionally known. See, for example, Japanese Published Patent Application No. 4-66786. 
     However, in a sorter of the type in which packets are sent from the bins to the high-capacity tray, if the tray reaches the limit of its capacity then Subsequent copy processing must be stopped. As a result, this reduces the productivity of the copy procedure. If copy processing were nonetheless to continue and subsequent sheets were to be sent to the sorter, then the sheets that could not be transferred to the tray and the sheets that were subsequently sent into the sorter would mix together, creating problems. 
     Thus, there reins an opportunity to improve the sorting and housing of paper in sorters. In particular, there exists a need for a paper processing apparatus and method that can perform continuous sorting for a number of packets exceeding the number of installed bins, and that can continue the image formation process even after the large-capacity tray to which the packets are transferred has reached the limit of its capacity. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a paper processing apparatus and method that, in paper sort mode, can perform continuous sorting for a number of packets exceeding the number of installed bins, and that can continue the image formation process even after the large-capacity tray to which the packets are transferred has reached the limit of its capacity. 
     In order to attain the above object, an apparatus and method for processing paper ejected from an image forming device are disclosed. The apparatus comprises a plurality of bins for sorting the paper ejected from the image forming device into packets, and for housing the packets, a tray for stacking the packets; packet conveying device for conveying the packets from the plurality of bins to the tray, detecting device for detecting the maximum amount of paper that can be stacked onto the tray; and control device for halting the packet conveying device when the detecting device detects the maximum amount of paper that can be stacked onto the tray, for counting the number of empty bins from which the packets have already been removed, for transmitting the counted number of empty bins to an image forming device controller, and for controlling the guiding the of paper subsequently ejected from the image forming device in the empty bins. 
     In the invention, where, for example, 30 packets are to be made but only 20 bins exist to handle them, initially the copy operations for the first 20 packets are performed, and one packet is sent to and housed in each bin. The packets are then removed from the bins and conveyed to and housed in the large-capacity tray by device of the packet conveying means. The subsequent copy operations for the remaining 10 packets are then performed. In this example, where it is detected by the detecting device that the tray has reached the limit of its capacity when the 17 th  packet has been sent to the tray to be housed, the operation of the packet conveying device is stopped temporarily and the counted number of empty bins from which packets have been removed (in this case, 17) is sent to the image forming device controller. The image forming device then performs copying for the remaining 10 packets, and the paper ejected from the image forming device is distributed to and housed in the empty bins. 
     As is clear from the above explanation, since the number of empty bins is counted and the sheets that are subsequently sent to the sorter are housed in the empty bins, the image forming operation need not be completely prohibited even when the large-capacity tray has become full. Instead, the image forming operation can be continued in accordance with the number of empty bins, and this results in an improved copying efficiency. Moreover, the problem of sheets already housed in the bins becoming commingled with the sheets newly sent to the bins can be prevented. 
     The above features and advantages of the invention will be better understood from the following detailed description taken into conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following description, like parts are designated by like reference numbers throughout the several drawings. 
     FIG. 1 is an elevational view of the external appearance of a stapler/sorter comprising an embodiment of the invention and a copying machine. 
     FIG. 2 is a drawing showing the basic construction of the stapler/sorter. 
     FIG. 3 is a drawing explaining the packet removal and stacking operations in the stapler/sorter. 
     FIG. 4 is a drawing continuing the explanation of FIG. 3 of the packet removal and stacking operations in the stapler/sorter. 
     FIG. 5 is a drawing continuing the explanation of FIG. 4 of the packet removal and stacking operations in the stapler/sorter. 
     FIG. 6 is a drawing continuing the explanation of FIG. 5 of the packet removal and stacking operations in the stapler/sorter. 
     FIG. 7 is a drawing continuing the explanation of FIG. 6 of the packet removal and stacking operations in the stapler/sorter. 
     FIG. 8 is a drawing continuing the explanation of FIG. 7 of the packet removal and stacking operations in the stapler/sorter. 
     FIG. 9 is a block diagram showing the controller for the copying machine and the stapler/sorter. 
     FIG. 10 is a flow chart showing the main routine of the control sequence of the CPU controlling the stapler/sorter. 
     FIG. 11 is a flow chart showing the sorting subroutine. 
     FIG. 12 is a flow chart showing the stacking subroutine. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the paper processing apparatus pertaining to the invention will be explained below with reference to the accompanying drawings. In the embodiment explained below, the invention is applied in a stapler/sorter connected to an electrophotographic copying machine. 
     In FIG. 1, reference numeral  1  is an electrophotographic copying machine and reference numeral  10  is a stapler/sorter. Copying machine  1  forms images on paper using the public domain electrophotographic method, and is equipped with recycle-type automatic original document feeder  5  on top it. This automatic original document feeder  5  feeds the pages of a multi-page original document that sits in a tray to the platen glass in proper page sequence, ejects them from the platen glass when exposure of the number of copies designated by the operator has been performed, and then returns them to the tray. 
     Referring to FIG. 2, the stapler/sorter  10  comprises essentially a large-capacity non-sort tray  20  a bin assembly  30  having  20  bins  31  ( 31   1  through  31   20 ), a removal unit  40  to remove the packets housed in the bins  31 , a stapling unit  70 , a paper conveying unit  80 , a packet conveying gate  100 , and a punch unit  120 . 
     The stapler/sorter  10  can process sheets of paper on which images have been formed and that have been ejected from copying machine  1  in accordance with the various modes described below: (1) stacking of sheets in non-sort tray  20  without sorting them (non-sort mode), (2) sorting of sheets into bins  31  in proper page sequence (sort mode), (3) stapling of sorted packets (sort/staple mode), (4) removal of stapled packets housed in bins  31  and stacking the packets in non-sort tray  20  (sort/staple/stack mode), (5) removal of sorted packets from bins  31  and stacking them in non-sort tray  20  without stapling them (sort/stack mode), (6) distributing each page of a document to a different bin  31  (group mode), (7) stapling of grouped packets (group/staple mode), (8) removal of stapled packets from bins  31  and stacking them in non-sort tray  20  (group/staple/stack mode), and (9) removal of grouped packets from bins  31  and stacking them in non-sort tray  20  without stapling them (group/stack mode). Moreover, each of these modes can be combined with punch processing, in which punch holes are formed on a single sheet basis at a time while paper conveyance by paper conveying unit  80  is underway. 
     The internal construction of stapler/sorter  10  will now be explained in detail. 
     First, paper conveying unit  80  comprises a pair of receiving rollers  81  that receive sheets ejected from copying machine  1 , a switching claw  82  that switches the direction of paper conveyance, a first conveying assembly  83  that extends essentially vertically, and a second conveying assembly  90  that extends essentially horizontally from the first conveying assembly  83  toward bin assembly  30 . The switching claw  82  is mounted with pin  82   a  as a fulcrum such that it can rotate based on the switching ON and OFF of solenoid SL 50 . When the solenoid SL 50  is in the OFF state, the switching claw  82  is set in the position indicated by the solid line in FIG.  2 . When this condition is present, the sheet being received by the pair of receiving rollers  81  are guided by the curved, right-hand side surface of the switching claw  82  and sent to the first conveying assembly  83 . When the solenoid SL 50  is in the OFF state, the switching claw  82  revolves slightly in a clockwise direction. When this condition is present, the sheets are guided by the top surface of the switching claw  82  and guide plate  79  and conveyed onto the non-sort tray  20  via packet conveying gate  100 . This is further explained below. 
     The first conveying assembly  83  comprises guide plates  84 .  85 ,  86  and  87 , as well as pairs of conveying rollers  88  and  89 . The second conveying assembly  90  comprises conveying rollers  91  and  92 , as well as guide plates  93  and  94 , and can rotate approximately 90° upward with shaft  95  as a fulcrum. When the sort mode or group mode is active, the second conveying assembly  90  is set in the conveyance position indicated by the solid line in Fill.  2 , and sends sheets conveyed from the first conveying assembly  83  to the bins  31  via the conveying rollers  91  and  92 . When packet removal processing is performed as explained below, the second conveying assembly  90  rotates approximately 90° in a counter-clockwise direction with the shaft  95  as a fulcrum, rising, and retracting from the paper conveying position. 
     The pair of rollers  81 ,  88  and  89  and the rollers  91  and  92  are driven to rotate by motor M 50 . 
     The bin assembly  30  comprises  20  bins  31   1  through  31   20 . Each bin  31  is oriented diagonally at a fixed distance from the adjacent bins, and engages with a spiral thread formed on the outer circumference of a drive shaft not shown in the drawings, on which pins  32  at the lower ends of the bins  31  are vertically mounted. By rotating this drive shaft forward or backward by means of motor M 60 , the bins  31  are raised or lowered by one pitch through one rotation of the drive shaft. The position indicated by the solid line in FIG. 2 is the lowermost position (home position) of the bin assembly  30 . When it is in this position, the first bin  31   1  faces the conveying rollers  91  and  92 . From here on, the position of bin  31  facing the conveying rollers  91  and  92  is termed level X 2 . When the drive shaft rotates once backward, the first bin  31   1  descends to level X 1 , and the packet is bound by staple unit  70  at this level X 1 . When the drive shaft rotates once forward, the first bin  31   1  rises to level X 2 , and the packet is removed at this level X 2 . At this time, the subsequent bins  31   2  through  31   20  also rise one pitch, and the bin  31   2  is set at level X 1 . When any bin  31  is set at levels X 1  or X 2 , the spacing between itself and the adjacent bins  31  above and below is set more widely. The setting of the bin spacing is obtained by changing the pitch of the spiral thread of the drive shaft. 
     The removal unit  40  will now be explained. 
     The removal unit  40  grasps and removes a packet from the bin  31  set at level X 2 , and comprises essentially an upper roller  42  supported by an upper arm  45 , and a lower roller  43  supported by a lower arm  46 . When the second conveying assembly  90  retracts upwards, the upper arm  45  rotates counter-clockwise using shaft  95  as a fulcrum, and the lower arm  46  rotates clockwise using shaft  47  as a fulcrum. As a result, the leading edge of the packet in the bin  31  is grasped and lifted by the rollers  42  and  43 , and the packet is removed through the driven rotation of the rollers  42  and  43 . 
     Next, the packet conveying gate  100  will be explained. 
     The packet conveying gate  100  is equipped with a pair of rollers  102  and  103 , as shown in FIG.  2 . The rollers  102  and  103  can rotate in a forward or backward direction by motor M 21 . This packet conveying gate  100  is guided by a guide in ember not shown in the drawings such that it may rise or descend, and the motor M 20  operates as its drive source. The home position of the packet conveying gate  100  is the position indicated by the solid line in FIG. 2, and at this home position, the gate  100  conveys packets sent from the pair of receiving rollers  81  while being guided by the upper surface of the switching claw  82  to the left in FIG.  2  through the rotation of the rollers  102  and  103 , and sends them to the non-sort tray  20 . 
     On the other hand, in order to receive stapled or non-stapled packets, the packet conveying gate  100  descends to the position facing the bin  31  set at level X 2  (see FIG.  3 ). At this removal position, the gate  100  grasps by means of rollers  102  and  103  packet S grasped and then removed from the bin  31  by the removal rollers  42  and  43  (see FIG.  4 ), and places packet S in the gate  100  based on the forward rotation of the rollers  102  and  103  (see FIG.  5 ). When the packet S is completely received by the gate  100 , the forward rotation of the rollers  102  and  103  stops, and the gate  100  simultaneously rises (see FIG.  6 ). When the gate  100  rises to a prescribed height, the rollers  102  and  103  rotate backward, and the grasped packet S is ejected onto the non-sort tray  20  (see FIG.  7 ). The gate  100  then descends to the removal position (see FIG.  8 ), and the stacking operation is repeated. 
     The packet conveying gate  100  normally ejects non-sort sheets onto the tray  20  one sheet at a time at the position indicated in FIG. 2 (home position), and when the packets are stacked, the gate  100  begins ejecting packets onto the tray  20  from a position slightly lower than the home position. As the number of packets stacked on the tray  20  increases, the gate  100  rises above the home position and then stops, whereupon its packet is ejected onto the tray  20 . The position at which the gate  100  rises and stops corresponds to a position at which a fixed distance is maintained between the packet ejection height from the rollers  102  and  103  and the top surface of the sheets stacked on the tray  20 . In other words, the gate  100  rises to a position at which it can drop the next packet from a prescribed distance to the top surface of the paper on the tray at all times. 
     Incidentally, a sensor SE 23  is provided for detecting the accumulation of sheets of paper on the non-sort tray  20  to its maximum capacity by detecting the top surface of the paper on tray  20 . The sensor SE 23  is located above the tray  20 . 
     The stapling unit  70  will now be explained. 
     The stapling unit  70  consists of a public domain motor-powered mechanism, and comprises a head member  71  on which a cartridge that holds staples can be detachably mounted and an anvil member  72  that catches and bends staples that have been fired from the head member  71 . This stapling unit  70  moves toward the bin  31  set at the level X 1 , and drives staples into the packets at one corner location or two center locations (see FIG.  4 ). In other words, where the front side of the stapler/sorter  10  is deemed the home position, the stapling unit  70  moves toward the back side, stops at a prescribed position, moves toward the bin  31  drives in a staple, and finally returns to the home position. 
     FIG. 9 shows the controller for the copying machine  1  and the stapler/sorter  10 . This controller mainly comprises a CPU  125  for controlling the copying machine  1 , and a CPU  130  for controlling the stapler/sorter  10 . The CPU  130  is equipped with a ROM  131  that houses a control program and a RAM  132  that houses the parameters for the execution of the control program, and is connected to the sensor SE 23  and the motors M 20  and M 21  by I/O ports  133 . The CPUs  125  and  130  exchange information by interface  140 . 
     The sort mode operation of the stapler/sorter  10  having the construction described above will now be briefly explained. 
     The automatic original document feeder  5  can count how many times the original document has been recycled to the automatic original document feeder for copying, and in the sort mode, where the set number of copies exceeds  21 , the original document is recycled for copying jobs comprising 20 copies each. For example, where the number of packets to be made is  50 , first, 20 copies of each original document are made and distributed to bins  31   1  to  31   20  (first cycle). This is termed job one. After job one is completed, the packets in the bins  31  are sequentially stapled if necessary, and are then stacked on the non-sort tray  20  by the packet conveying gate  100 . Another 20 copies are then made of the original document (second cycle), distributed to the bins  31   1  through  31   20 , and stacked on the tray  20  as before. In the third cycle, the original document is copied 10 times, and the copies are distributed to the bins  31   1  through  31   10  and then stacked on the tray  20 . 
     Incidentally, when the 37 th  packet has been stacked on the tray  20 , if it is detected by the sensor SE 23  that the maximum capacity of the tray has been exceeded, then the gate  100  is held at the home position, and subsequent stacking operations are prohibited. The CPU  130  then counts the number of empty bins from which the packets were removed (in this case 17), and transmits the counted number of empty bins (17) to the CPU  125 . The CPU  125  compares the transmitted number of empty bins and the number of packets remaining to be made, sets the number of packets to be made, which is less than the number of empty bins, and continues copying. In this example, because the number of empty bins is 17 and the number of remaining packets to be made is 10, copying for 10 packets is performed. The remaining 10 packets made are distributed to the empty bins  31 . If the packets are removed from the non-sort tray  20  during this time, then the packets distributed to the bins  31  are stacked on the tray  20  by the gate  100 . 
     The control process of the CPU  130  will now be explained with reference to the flow charts of FIGS. 10 through 12. 
     FIG. 10 shows the main routine for the CPU  130 . 
     When the power is turned ON and the program starts, first, in step S 1 , various control parameters and various devices are initialized. In step S 2 , the internal timer is started. Next, the subroutines of steps S 3  through S 7  are called in sequence and necessary processing is performed. Finally, when the ending of the internal timer is confirmed in step S 8  the CPU  130  returns to step S 2 . 
     In step S 3 , detection signals from various sensors, etc., in the stapler/sorter  10  are read. In step S 4 , the control signals are output to various motors, etc. In step S 5 , the routine to sort sheets that are sent from the copying machine  1  to the stapler/sorter  10  and to house them in the bins  31  is performed. In step S 6 , the routine to convey the packets housed in each bin  31  to the non-sort tray  20  for stacking is performed. In step S 7 , other routines such as the detection of paper jam is performed. 
     FIG. 11 shows the subroutine for the sorting operation performed in the step S 5 . 
     First, when it is confirmed in step S 11  that copying by copying machine  1  has begun, the routine to sort the copy sheets into the bins  31  is begun in step S 12 . Next, when it is confirmed in step S 13  that the sheets have been ejected to the prescribed bins  31 , the number of ejected copy sheets is counted in step S 14  and the next bin  31  is moved to paper eject level X 2  in step S 15 . 
     Then in step S 16 , it is determined whether or not the last paper for job one has been ejected. If it has, sorting is stopped in step S 17 . 
     FIG. 12 shows the subroutine for the stacking operation performed in step S 6 . First, it is determined in step S 21  whether or not the job one has been completed. If the job one has not been completed (if copying is still underway), in step S 30  the holding operation is performed i.e., the removal unit  40  or the gate  100  are held in a stand-by state. If the job one is completed, after confirmation in step S 22  that the stack mode has been set, a bin  31  from which a packet is to be removed is sought in step S 23 . Where it is determined in step S 24  that such a bin exists, the bin  31  is moved to the level X 2  in step S 25  and stacking is performed. The number in the empty bin counter is then increased by 1 in step S 26 . 
     It is then determined in step S 27  based on detection signals from the sensor SE 23  whether or not the capacity of the non-sort tray  20  is being exceeded. If its capacity is not being exceeded, then the processes of steps S 24  through S 26  are repeated. If its capacity is being exceeded, then the stacking operation is prohibited in step S 28 , and the number in the empty bin counter is transmitted to copying machine control CPU  125  in step S 29 . The CPU  125  then sets the remaining number of copies to be performed based on the transmitted number of empty bins and continues the copying operation. When this occurs, the copy sheets ejected from the copying machine  1  are distributed to the empty bins  31 . 
     The paper processing apparatus pertaining to the invention is not limited to the embodiment described above, and may be modified in various ways within its essential scope. 
     For example, the stapling unit  70  and the punch unit  120  are not essential to the invention. 
     Moreover, the invention may be applied in an apparatus other than the copying machine  1 , such as a sorter connected to a printer that outputs image information transmitted from a host computer as hard copies. 
     While the invention has been described in detail with reference to a preferred embodiment and selected variations thereof it should be apparent to those skilled in the art that many modifications and variations are possible without departure from the scope and spirit of the invention as defined in the appended claims.