JP5760725B2 - Paper processing apparatus and image forming system - Google Patents

Description

  The present invention relates to a paper processing apparatus and an image forming system, and in particular, binding processing to sheet-like recording media (hereinafter referred to as paper in the present specification) such as paper, transfer paper, printing paper, and OHP sheets. And a sheet processing apparatus that performs predetermined processing such as folding processing, and an image forming system that includes the sheet processing apparatus and an image forming apparatus such as a printer, a copy, a facsimile, and a digital multifunction peripheral that combines these functions. About.

  Nowadays, a sheet processing apparatus that performs processing such as alignment, sorting, punching, edge binding, saddle stitching, and folding on an image-formed sheet is connected to the subsequent stage of the image forming apparatus to constitute one system. Increasing use. For this reason, this type of apparatus is also referred to as a sheet post-processing apparatus.

  As such a sheet post-processing apparatus, for example, the inventions disclosed in Patent Document 1 (Japanese Patent No. 3417994) and Patent Document 2 (Japanese Patent No. 3617936) are known. Among them, Patent Document 1 discloses a sheet output path of a copier in order to output a sheet without delaying or interrupting printing in the copier even when the compiler discharges paper discharged from the copier and binds the book. A turning chute branched from the output path and a turning gate at the entrance of the chute are provided upstream of the output feed roller, and the succeeding first sheet is kept while the job set is organized and bound by the compiler tray. Is stopped by the output feed roller, rotated in the reverse direction, sent upstream, and temporarily stored in the chute via the gate, and the first sheet is removed from the chute by the feed roller when the second sheet passes through the gate. A technology has been developed to return to the output path and to discharge to the compiler tray with the first and second sheets overlapped. It is.

  Further, in Patent Document 2, in order to avoid a decrease in productivity in image formation without complicating the configuration, increasing the size, and increasing the cost, a predetermined position on the conveyance path of the post-processing apparatus is provided. When a switching claw is provided as a backflow prevention means, and only allows passage of the paper in the transport direction, and the post-processing unit is not in a state of accepting the first paper of the next part without completing the post-processing of the previous part, The control means reversely rotates the transport roller and the transport roller pair so that the leading sheet passing through the switching claw waits in the branch path, and then the transport roller and the transport roller pair rotate forward, and the next sheet is transported. In other words, a technique is disclosed in which sheets that have been waiting are conveyed in a stacked state and discharged onto a post-processing tray in the post-processing unit. In addition, reverse rotation means rotating in the direction of conveyance toward the inlet side, and normal rotation means rotating in a direction away from the inlet side.

  By the way, in the invention described in Patent Document 1, the paper that is temporarily held by the turning chute (branch path) is completely transferred to the turning chute (branch path) by the switchback, and the turning gate (branch claw) is the output path. If the (conveyance path) is not opened, the turning gate (branch claw) and the next sheet to be conveyed collide with each other, so it is necessary to provide a certain interval between sheets in the image forming apparatus. At that time, the sheet is kept waiting on the branch path for the time required for the post-processing time so that the image forming apparatus does not open the sheet between the sheets as much as possible. However, since it is necessary to provide a certain interval between the sheets on the image forming apparatus side, it cannot be denied that the productivity of the entire image forming system is lowered.

  Therefore, in the invention described in Patent Document 2, the control unit reversely rotates the transport roller and the transport roller pair so that the leading sheet passing through the switching claw waits on the branch path, and then the transport roller and the transport roller pair are correctly set. It is rotated so that the next sheet to be conveyed and the waiting sheet are superimposed and conveyed. However, the branching claw is always pressed by a spring or the like so as to block the conveyance path, and is in a position where the branching path is opened. After the end passed through the branch path, the paper was sent to the branch path so as to be transported in a switchback manner. In this case, since the sheet being conveyed on the conveyance path is always in contact with the direction pressed by the branching claw, the sheet and the image forming surface of the sheet may be damaged.

  Therefore, the problem to be solved by the present invention is to enable paper processing without damaging the paper or the image forming surface of the paper while maintaining productivity.

In order to solve the above-described problems, the present invention provides a first conveyance path that is branched by a branching unit and connected to a second conveyance path on which a sheet waits, and a sheet that is conveyed along the first conveyance path. First conveying means for conveying in a first direction that is the conveying direction and a second direction that is opposite to the conveying direction, and the first conveying path and the second conveying path at the branch portion The guide means for guiding the paper by setting the first state in which both of the above are opened, or the second conveyance path is set in the second state in which the first conveyance path is shut off, and the paper is on standby In this case, the guide means is set in the second state to transport the first transported paper in the second direction, and the next transported paper is transported to the standby destination. and when conveyed together with the sheet, and set the guide means to said first state, said superimposed sheets first And a control means for conveying in a direction, the control means, after the rear end with respect to said first direction of the sheet conveyed earlier conveyed in the second direction passes through the branch portion, the before the tip with respect to said first direction of the sheet passes through the branch portion, it is conveyed to the first direction then superimposed sheets conveyed conveyed in the first direction to the paper The first conveying means is composed of a conveying roller which can be rotated in the forward and reverse directions and located downstream of the branching portion in the first direction. Two positions of the position where no conveying force is applied are set, and the second conveying means is provided in the second conveying path, and the sheet is disposed downstream of the first direction and the second conveying path. In the third direction on the side, and the first conveying means The second conveying means is arranged at an interval smaller than the minimum dimension in the conveyance direction of the paper to be conveyed, and the rear end side of the paper is waiting on the second conveyance path with respect to the first direction. And when the leading end side of the sheet is out of the nip of the first conveying means, the first conveying means maintains the nip state, When the leading end side of the sheet is in a position where it is nipped by the first conveying means, the first conveying means is set in a nip open state .

  According to the present invention, paper processing can be performed without damaging the paper or the image forming surface of the paper while maintaining productivity.

1 is a diagram illustrating a schematic configuration of an image forming system including a sheet processing apparatus and an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a schematic configuration of a sheet post-processing apparatus as the sheet processing apparatus in FIG. 1. FIG. 2 is a block diagram illustrating a control configuration of the image forming system illustrated in FIG. 1. FIG. 4 is an enlarged view showing a main configuration of a sheet post-processing apparatus along a horizontal conveyance path. FIG. 9 is an operation explanatory diagram of the conveyance process according to the first exemplary embodiment, showing a state where both the previous sheet and the next sheet are positioned on the horizontal conveyance path. FIG. 9 is an operation explanatory diagram of the conveyance process according to the first exemplary embodiment and illustrates a state when a preceding sheet is positioned on a branch path and a next sheet enters the branching unit. FIG. 9 is an operation explanatory diagram of the conveyance process according to the first exemplary embodiment and illustrates a state where a previous sheet and a next sheet are superimposed and conveyed. It is a figure which shows the detail of operation | movement of the upper branch nail | claw and the lower branch claw in FIG. FIG. 9 is an operation explanatory diagram of the conveyance process according to the second exemplary embodiment, showing a state where both the previous sheet and the next sheet are positioned on the horizontal conveyance path. FIG. 9 is an operation explanatory diagram in the conveyance process of the second embodiment and shows a state when a previous sheet is positioned on a branch path and a next sheet enters the branching section. FIG. 9 is an operation explanatory diagram of the conveyance process according to the second exemplary embodiment and illustrates a state where a previous sheet and a next sheet are superimposed and conveyed. The figure which shows the modification of the branch path in Example 2, and its function shows a difference with the branch path of Example 1. FIG. FIG. 9 is a diagram illustrating a modification example of the branch path and its function in the second embodiment, and shows a paper state in the branch path. FIG. 10 is an enlarged view illustrating a configuration of a main part along a horizontal conveyance path of a sheet post-processing apparatus according to a third embodiment. FIG. 10 is an operation explanatory diagram according to the third exemplary embodiment, showing a state where both the previous sheet and the next sheet are positioned on the horizontal conveyance path. In operation | movement explanatory drawing in Example 3, the state when the previous paper is located in a branch path and the next paper approached into the branch part is shown. FIG. 10 is an operation explanatory diagram according to the third exemplary embodiment and illustrates a state when the next sheet overlaps the previous sheet. FIG. 10 is an operation explanatory diagram according to the third exemplary embodiment and illustrates a state in which the previous paper and the next paper are conveyed while being overlapped.

  In the present invention, the paper that has been transported to the standby path in the branch path temporarily branched from the transport path is guided to the branch path from the branch claw by the switchback, and the branch claw is operated before the transport is completed, The conveyance path can be opened for the next sheet to be conveyed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals are given to components that can be regarded as the same or the same, and duplicate descriptions are omitted as appropriate.

FIG. 1 is a diagram illustrating a schematic configuration of an image forming system including a sheet processing apparatus and an image forming apparatus according to an embodiment of the present invention.
In FIG. 1, the image forming system includes an image forming apparatus 1 and a sheet processing apparatus 2 connected to a subsequent stage of the image forming apparatus 1. Since the sheet processing apparatus 2 is a sheet post-processing apparatus that performs post-processing on a sheet on which an image has been formed in the subsequent stage of the image forming apparatus 1, the sheet processing apparatus 2 will be described below as a sheet post-processing apparatus 2.

  The image forming apparatus 1 includes an image forming engine, and forms an image on a sheet based on image data input by a local connection from a scanner or PC (Personal Computer) (not shown), or input via a network, or Print and discharge to the next stage. As the image forming engine, a known engine such as an electrophotographic method or a droplet discharge method such as an ink jet is used. Here, since the image forming apparatus 1 only needs to have a function of forming an image on a sheet, the method of the image forming engine is not limited.

  2 is a diagram illustrating a schematic configuration of the sheet post-processing apparatus 2, FIG. 3 is a block diagram illustrating a control configuration of the image forming system illustrated in FIG. 1, and FIG. 4 is a schematic diagram of the sheet post-processing apparatus 2 along the horizontal conveyance path. It is an enlarged view which shows a part structure. The sheet post-processing apparatus 2 includes punching means (piercing unit 4), alignment means (jogger 9, staple rear end rear end fence 23), binding means (end binding stapler 12), and the like as sheet processing means. Further, in order to execute each of these processes, a horizontal conveyance path 20 for receiving a sheet from the image forming apparatus 1 and conveying it to the post-processing tray 8 side, and a proof conveyance path 17 for conveying the sheet to the proof tray 21 side are provided. Is provided.

  An entrance roller 3, a punching unit 4, a horizontal transport roller 5, an upper branch claw 15, a lower branch claw 19, and a switchback roller 6 are arranged in the horizontal transport path 20 from the transport upstream side to the downstream side. The proof conveyance path 17 is branched from the position of the upper branch claw 15, and a proof conveyance roller 16 and a proof discharge roller 18 are arranged. Further, a branch path (pre-stack path) 25 branches downward from the branch position 24 of the lower branch claw 19 of the horizontal conveyance path 20, and the pre-stack roller 7 is disposed in the branch path 25. In FIG. 4, the sheet P is carried from the main body discharge roller 1-1 of the image forming apparatus 1 to the entrance roller 3 of the sheet post-processing apparatus 2.

  A post-processing tray (stipple tray) 8 is provided on the most downstream side of the horizontal conveyance path 20, a jogger 9 on the side surface side of the post-processing tray 8, a tapping roller 10 on the upper surface side, and a rear end reference fence on the rear end side. 23 is arranged. A paper discharge roller 13 is provided on the most downstream side of the post-processing tray 8, and a driven roller of the roller pair of the paper discharge rollers 13 is rotatably supported by the paper discharge opening / closing guide plate 22. A paper discharge tray 14 is provided on the paper discharge side of the paper discharge roller 13 so as to be movable up and down, and an end binding stapler 12 is provided on the rear end reference fence 23 side.

  The control configuration of the paper post-processing apparatus 2 includes a control unit 201, a paper transport unit 202, a branch claw switching unit 203, a transport unit nip separation unit 204, sensors 205, and a post-processing unit 206. Are connected to each other so that signals can be transmitted and received. The post-processing unit 206 controls operations of the hitting roller 10, the jogger 9, the end binding stapler 12, and the discharge claw 11. The control unit 201 is communicably connected to the control unit of the image forming apparatus 1, and the sheet size, the number of sheets to be bound, and sheet conveyance information are transmitted from the image forming apparatus 1 to the control unit 201 of the sheet post-processing apparatus 2. In 201, the respective units are controlled based on the received information.

  The control unit 201 includes a CPU, a ROM, and a RAM. The CPU reads out a program stored in the ROM, expands the program in the RAM, and executes processing defined by the program while using the RAM as a work area and a data buffer. To do.

  In the sheet post-processing apparatus 2 configured in this manner, the proof is set in three modes: a discharge mode, a straight discharge mode, and a stipple mode. Perform the action. This operation is executed under the control of the control unit 201.

The proof paper discharge mode is a mode in which the paper P is conveyed from the image forming apparatus 1 and discharged to the proof paper discharge unit 21 via the horizontal conveyance path 20 (upstream side) and the proof conveyance path 16. In this mode, the sheet is conveyed by the entrance roller 3, the horizontal conveyance roller 5, and the proof conveyance roller 16, and is discharged by the proof discharge roller 18. At that time, the upper branch claw 15 is positioned in a direction in which the sheet is guided in the direction of the proof conveyance path 16 by a driving unit (not shown) (for example, a motor and its power transmission mechanism), and switches the conveyance path. The operation timing of the upper branch claw 15 is set based on the timing when the entrance sensor 26 detects the leading edge of the sheet. In the following description, the paper is indicated by a reference symbol P, the front end of the paper is indicated by a reference symbol Pf with a subscript f, and the rear end of the paper is indicated by a subscript b by a reference symbol Pb. Also, for the first sheet P1, the straight sheet discharge mode in which the front end of the sheet is P1f and the rear end of the sheet is P1b with the number of subscripts 1 and 2 is conveyed from the image forming apparatus 1. In this mode, the paper is discharged to the paper discharge tray 14 through the horizontal conveyance path 20. In this mode, the paper P is transported by the entrance roller 3, the horizontal transport roller 5, and the switchback roller 6, and is discharged to the paper discharge tray 14 by the paper discharge roller 13. The switchback roller 6 is a roller that can rotate in the forward direction and the reverse direction, and rotates in the forward rotation direction (paper discharge direction) during straight discharge. The upper branch claw 15 and the lower branch claw 19 are stopped at a position where the horizontal conveyance path 20 is opened. This position is the default position of the upper branch claw 15 and the lower branch claw 19 (see FIG. 4).

  The stipple mode is a mode in which a sheet is conveyed from the image forming apparatus 1 and a plurality of sheets are bound in the post-processing tray 8 from the date to the post-processing tray 8 through the horizontal conveyance path 20. In this mode, the sheet is conveyed by the entrance roller 3, the horizontal conveyance roller 5, and the switchback roller 6 and stacked on the post-processing tray 8. The paper discharge opening / closing guide plate 22 is open, and the nip of the paper discharge roller 13 is in a separated state. The switchback roller 6 can rotate in the forward direction and the reverse direction, and rotates in the forward direction during post-processing of the staple mode. The upper branch claw 15 and the lower branch claw 19 are located at a default position where the horizontal conveyance path 20 is opened.

  The paper discharged to the post-processing tray 8 is knocked down by the hitting roller 10, and the rear end of the paper is abutted against the rear end reference fence 23. As a result, the rear end reference fence 23 is used as a reference for alignment in the transport direction. The hitting roller 10 rotates in the direction in which the sheet is conveyed to the rear end reference fence 23, and repeats the operation of contacting the sheet each time the sheet is discharged and then waiting. Further, the jogger 9 aligns the direction perpendicular to the transport direction. The operation timing of the hitting roller 10 and the jogger 9 is operated after a predetermined time has elapsed from the timing when the staple paper discharge sensor 28 detects the trailing edge of the paper.

  This operation is repeated for the number of sheets corresponding to one part of the sheet conveyed from the image forming apparatus 1 to form a sheet bundle in which the sheet conveyance direction and the direction orthogonal to the sheet conveyance direction are aligned. The rear end portion is bound by the end binding stapler 12. The bound sheet bundle is pushed up by the discharge claw 11 that moves along the upper surface of the post-processing tray 8 and is discharged onto the discharge tray 14. The operation timing of the edge binding stapler 12 and the discharge claw 11 is set based on the timing when the staple paper discharge sensor 28 detects the trailing edge of the final sheet, and operates after a predetermined time has elapsed from the timing.

  In the present embodiment, the discharge opening / closing guide plate 33 is always open during the staple mode operation, and the nip of the discharge roller 13 is always away.

  Hereinafter, it explains in detail divided into each example.

  5 to 7 are diagrams illustrating operations in the conveyance process according to the first embodiment. The configuration of each part has been described with reference to FIGS.

  Example 1 is an example in the case of prestacking in the stipple mode. In this case, the first sheet P1 is prestacked on the branch path 25. That is, the first sheet P1 of the sheet bundle to be post-processed is conveyed from the image forming apparatus 1, and at this time, the upper branch claw 15 and the lower branch claw 19 are positions where the horizontal conveyance path 20 is opened, that is, It stops at the default position. The switchback roller 6 stops when the rear end P1b of the first sheet P1 conveyed along the horizontal conveyance path 20 passes the branch position 24. Next, the lower branching claw 19 rotates to a position for guiding the paper P1 in the direction of the branching path 25, opens the entrance side of the branching path 25, and closes the upstream side of the horizontal conveyance path 20.

  In this state, as shown in FIG. 6, the switchback roller 6 rotates in the reverse direction, the first sheet P1 is switched back and conveyed to the branch path 25 from the sheet rear end P1b side. The operation timing of the switchback roller 6 and the lower branch claw 19 is after a lapse of a predetermined time from the timing when the staple paper discharge sensor 28 detects the paper trailing edge P1b. This predetermined time is appropriately set according to the distance between the detection position of the staple paper discharge sensor 28 and the nip of the switchback roller 6 and the conveyance speed. FIG. 5 shows a state immediately before the sheet trailing edge P 1 b enters the branch path 25. Further, FIG. 5 shows a state in which the sheet bundle Pa of the previous job is bound by the end binding stapler 12 on the post-processing tray 8 and discharged by the discharge claw 11.

  The rear end P1b of the first sheet P1 transported by the switchback reaches the nip of the prestack roller 7, and is further transported downward in the drawing in the branch path 25. The prestack roller 7 can be rotated forward and backward. In the present embodiment, the rotation direction of the pre-stack roller 7 is defined as forward rotation when conveyed in the downward direction in FIG. 2 and reverse rotation when conveyed in the horizontal conveyance path 20 direction.

  When the leading edge P1f of the first sheet P1 passes through the nip of the switchback roller 6, the switchback roller 6 stops and waits. The prestack roller 7 also stops. The lower branching claw 19 switches to a direction in which the sheet is conveyed to the horizontal conveyance path 20 and opens the horizontal conveyance path 20. At this time, the operation timings of the switchback roller 18, the lower branching claw 19, and the prestack roller 7 are set after a predetermined time has elapsed from the timing when the prestack sensor 29 detects the paper trailing edge Pb. The prestack sensor 29 is provided on the downstream side in the transport direction when the prestack roller 7 rotates in the forward direction of the prestack roller (in the direction of arrow R3).

  When the second sheet P2 is carried in from the image forming apparatus 1 and conveyed along the horizontal conveyance path 20, the leading edge Pf of the second sheet P2 and the first sheet P1 that has been waiting are transferred. The prestack roller 7 rotates in the reverse rotation direction at the timing when the leading ends Pf are substantially aligned, and the switchback roller 6 rotates in the normal rotation direction (arrow R1 direction). As a result, as shown in FIG. 7, the leading ends P1f and P2f of the first sheet P1 and the second sheet P2 are overlapped and conveyed to the post-processing tray 8 side, and discharged to the post-processing tray 8.

  The overlapping timing is determined by a branch sensor 27 arranged immediately after the branching portion to the proof transporting path 17 (in the vicinity of the leading end of the upper branching claw 15 on the horizontal transporting path 20 side) detecting the second sheet of paper P2. It's time later. Thereafter, a predetermined number of sheets are discharged to the post-processing tray 8, aligned in the transport direction and the direction perpendicular to the transport direction, stapled, and discharged by the discharge claw 11.

  On the other hand, the sheet bundle Pa of the previous job on the post-processing tray 8 is bound by the edge binding stapler 12 and discharged by the discharge claw 11 during this period. As a result, when the two sheets P1, P2 of the next job are discharged to the post-processing tray 8, the paper bundle Pa of the previous job does not exist on the post-processing tray 8.

  FIG. 8 is a diagram showing details of the operation of the upper branch claw 15 and the lower branch claw 19 in FIG. FIG. 4A shows a state when the lower branching claw 19 is in the default position, and FIG. 5B shows a state when the lower branching claw 19 is operated. As described above, the upper branch claw 15 and the lower branch claw 19 are oscillated and driven by a motor (not shown) and a driving unit including a driving force transmission mechanism or a driving unit including a solenoid, as shown in FIGS. It is located at one of the two positions shown in FIG. The former is a position where both the horizontal conveyance path 20 and the branch path 25 are opened and can be conveyed, and the latter is a position where the horizontal conveyance path 20 is blocked and the branch path 25 is opened and the paper is branched. It is a position that can be guided in 25 directions.

  The paper shown in FIGS. 5 to 8 shows a state when the small-size paper P is conveyed. In the case of a small-sized sheet P, as shown in FIG. 6, the first sheet P1 is led from the rear end Pb to the branch path 25 following the horizontal conveyance path 20 by the reverse rotation of the switchback roller 6 (in the direction of arrow R2) (arrow). (D1 direction) When the second sheet P2 is conveyed in the direction of the arrow D2 and the sheet leading edge Pf tries to pass through the lower branch claw 19, the first sheet leading edge Pf passes through the nip of the switchback roller 6. Yes. Therefore, as shown in FIG. 7, when the switchback roller 6 is rotated forward (in the direction of arrow R1) from the state shown in FIG. 6, the first sheet P1 and the second sheet P2 are overlapped and the post-processing tray 8 is overlapped. Can be conveyed in the direction.

  However, in the case of a large-sized sheet having a large sheet size, when the leading end P2f of the second sheet P2 tries to pass through the lower branch claw 19 as shown in FIG. 6, even if the leading edge P2f of the second sheet P2 reaches the nip position of the switchback roller 6 and the switchback roller 6 is rotated forward in this state, the first sheet P1 The leading edge P1f and the leading edge P2f of the second sheet P2 cannot be matched. Therefore, in this embodiment, when the paper is large, the nip of the switchback roller 6 is opened (released) according to the paper transport state. The operation at this time is shown in the operation explanatory diagrams of FIGS. The operations in FIGS. 9 to 11 correspond to the operations in FIGS. 5 to 7 in the first embodiment.

  Note that the small size paper is, for example, B5 landscape size paper as the minimum paper size. This is because the distance between the switchback roller 6 in the horizontal conveyance path and the prestack roller 7 in the branch path 25, the distance between the entrance roller 3 and the horizontal conveyance roller 5, and the distance between the horizontal conveyance roller 5 and the switchback roller 6 are B5 horizontal size. This is because it is necessary to transport a sheet of this minimum paper size. The large size is assumed to be, for example, A3 vertical size or small size vertical (for example, A4 vertical size) paper.

  The second embodiment is an example in the case of prestacking a large size paper in the stipple mode. In this case, the first sheet P1 is prestacked on the branch path 25. That is, the first sheet P1 of the sheet bundle to be post-processed is conveyed from the image forming apparatus 1, and at this time, the upper branch claw 15 and the lower branch claw 19 are positions where the horizontal conveyance path 20 is opened, that is, It stops at the default position. The switchback roller 6 stops when the rear end P1b of the first sheet P1 conveyed through the horizontal conveyance path 20 passes the branch position 24. Next, the lower branching claw 19 moves to a position for guiding the paper P <b> 1 in the direction of the branching path 25, opens the entrance side of the branching path 25, and closes the upstream side of the horizontal conveyance path 20.

  In this state, the switchback roller 6 rotates reversely, and the first sheet P1 is switched back and conveyed to the branch path 25 from the sheet rear end P1b side. The rear end P1b of the paper P1 to be prestacked is nipped by the prestack roller 7, and the switchback roller 6 and the prestack roller 7 are stopped when the prestack sensor 29 detects the paper rear end P1b and transports it for a predetermined time. Then, the paper P1 to be prestacked stops. FIG. 9 shows a state immediately before the sheet trailing edge P1b enters the branch path 25 (immediately before the switchback roller 6 rotates reversely). In FIG. 9, the sheet bundle Pa of the previous job is in a state in which the rear end portion is bound by the end binding stapler 12 on the post-processing tray 8 and is discharged by the discharge claw 11.

  After the switchback roller 6 and the prestack roller 7 are stopped, as shown in FIG. 10, the switchback roller 6 leaves the nip state in the roller stop state (in the direction of arrow D11), and the nip state of the first sheet P1 is released. Then, the first sheet P1 enters a standby state. The nip opening operation of the switchback roller 6 is started after a predetermined time elapses from the detected timing when the prestack sensor 29 detects the trailing edge P1b of the first sheet P1.

  In this state, when the second sheet P2 is carried from the image forming apparatus 1 and conveyed along the horizontal conveyance path 20, the lower branch claw 19 moves to a position where the horizontal conveyance path 20 is opened. The lower branch claw 19 rotates in a direction to open the horizontal conveyance path 20 without waiting for the leading edge P2f of the second sheet P2 to pass through the lower branch claw 19. Then, as shown in FIG. 11, the prestack roller 7 rotates reversely (arrow R4) at the timing when the leading edge P1f of the first sheet P1 prestacked and the leading edge P2f of the next second sheet P2 are substantially aligned. Direction), and the pre-stacked first sheet P1 is sent out to the horizontal conveyance path 20.

  Simultaneously with the substantially aligned timing, the switchback roller 6 rotates in the forward rotation direction (arrow R1 direction) and operates from the nip open state to the nip state (arrow D12 direction). As a result, the leading edge P1f of the first sheet P1 and the leading edge P2f of the second sheet P2 are superposed in a substantially aligned state, and are discharged to the staple tray 8 in that state. At this time, as shown in FIG. 11, the nip of the paper discharge roller 13 is opened so that the paper discharge operation of the two stacked sheets P1 and P2 is not hindered.

  In this embodiment, the paper size is described as large. However, whether the paper size is pre-stacked and the leading end P1f side of the stopped paper is out of the nip of the switchback roller 6 (state in FIG. 6) or not. (State of FIG. 10). Accordingly, whether to control the small size or the large size is selected depending on the distance between the switchback roller 6 and the prestack roller 7, the prestack time, the stop position of the paper, and the like. Therefore, the size of the paper size is not only dimensional but also depends on the positional relationship of each element of the apparatus. Further, depending on the setting of the distance between the rollers of the switchback roller 6 and the prestack roller 7, the sheet size may not be limited and the nip of the switchback roller 6 may be controlled to be opened as in the second embodiment. .

  12 and 13 are diagrams showing a modification of the branch path 25 and its function in the second embodiment. In the second embodiment, the conveyance gap L2 of the introduction portion 25a to the branch path 25 is larger than the conveyance gap L1 of the horizontal conveyance path 20 or the introduction portion 25a of the branch path 25 of the first embodiment. That is, as shown in FIG. 12, the width is increased by the difference L3 between the guide plate 25b of the conveyance path 25 of the first embodiment and the guide plate 25c of the conveyance path 25 of the second embodiment. When the conveyance gap L2 is increased in this way, a sufficient gap with the guide plate 25c can be secured even when the lower branch claw 19 is in the default position, so that the paper P1 during switchback conveyance is pressed against the lower branch claw 19 This eliminates rubbing and reduces the conveyance resistance. The conveyance gap L1 is substantially the same as the conveyance gap in the horizontal conveyance path 20 upstream from the branch point 24 when the sheet is switched back.

  FIG. 14 is an enlarged view showing a main part configuration along the horizontal conveyance path of the sheet post-processing apparatus 2 according to the third embodiment. As shown in FIG. 14, in the third embodiment, instead of the prestack roller 7 provided in the branch path 25 as compared with the first embodiment, the first and second two-stage prestack rollers 30 and 31 are transported. Are provided in series. Other parts are the same as those in the first embodiment.

  FIGS. 15 to 18 are operation explanatory views showing the operation at the time of prestacking in the third embodiment. That is, in this third embodiment, the function of the prestack roller 7 of the first embodiment is the same as that of the second prestack roller 31 for transporting the paper downstream to the branch path 25 and the horizontal path 20 from the branch path 25. The first pre-stack roller 30 for feeding is divided. Thus, in the first embodiment, the prestack roller 7 rotates forward or reversely according to the conveyance state of the paper, but in the third embodiment, the first prestack roller 30 rotates only in the reverse direction (arrow R4 direction). The second pre-stack roller 31 was set to rotate only in the normal direction (in the direction of arrow R3). In both cases, two positions of a nip state and a nip open state can be taken by a drive unit (not shown).

  With this configuration, the first sheet P1 of the sheet bundle to be post-processed is conveyed from the image forming apparatus 1. At this time, the upper branch claw 15 and the lower branch claw 19 open the horizontal conveyance path 20. It is stopped at the position, that is, the default position shown in FIG. The switchback roller 6 stops when the rear end P1b of the first sheet P1 conveyed along the horizontal conveyance path 20 passes the branch position 24, and the lower branch claw 19 is moved as shown in FIG. The sheet P1 is moved to a position for guiding the sheet P1 in the direction of the branch path 25, the entrance side of the branch path 25 is opened, and the upstream side of the horizontal transport path 20 is closed.

  In this state, as shown in FIG. 16, the switchback roller 6 reversely rotates (in the direction of arrow R2), and the first sheet P1 is switched back and conveyed to the branch path 25 from the sheet rear end P1b side. At this time, the first prestack roller 30 is in the nip open state, and the second prestack roller 31 is in the nip state. The operation timing of the switchback roller 6 and the lower branch claw 19 is after a predetermined time has elapsed from the timing when the staple paper discharge sensor 28 detects the paper trailing edge P1b. The predetermined time is appropriately set according to the distance between the detection position of the staple paper discharge sensor 28 and the nip of the switchback roller 6 and the conveyance speed, as in the first embodiment.

  The rear end P1b of the first sheet P1 transported in the switchback arrives at the nip of the second prestack roller 31 and is further transported downward in the drawing 25 in the drawing. When the prestack sensor 29 detects the paper trailing edge P1b, the switchback roller 6, the second prestack roller 31, and the first prestack roller 30 stop after a predetermined time has elapsed from the detection timing. Next, the lower branching claw 19 switches to a direction in which the sheet is conveyed to the horizontal conveyance path 20 and opens the horizontal conveyance path 20. Further, when a predetermined time has elapsed, the first prestack roller 30 is switched to the nip state, and the second prestack roller 31 is switched to the nip separation state.

  As shown in FIG. 17, when the second sheet P2 is carried from the image forming apparatus 1 and is conveyed along the horizontal conveyance path 20, the leading edge P2f of the second sheet P2 and The first prestack roller 30 rotates in the reverse direction (in the direction of arrow R4) at the timing when the leading edge P1f of the first sheet P1 that has been waiting is substantially aligned, and the first sheet P1 is moved along the horizontal conveyance path 20. Send out in the direction. At the same time, the switchback roller 6 rotates in the forward direction. As a result, as shown in FIG. 18, the first sheet P 1 and the second sheet P 2 are overlapped and conveyed to the post-processing tray 8 side, and discharged to the post-processing tray 8.

  As for the overlapping timing, the branch sensor 27 detects the second sheet and operates after a predetermined time. Thereafter, a predetermined number of sheets are discharged to the staple tray 6, aligned in the transport direction and the direction perpendicular to the transport direction, stapled, and discharged by the discharge claw.

  In the first to third embodiments, only one sheet is waited on the branch path 25, but a plurality of sheets can be waited. The number of sheets to wait is appropriately set according to the post-processing time of the previous job (copy).

As described above, according to the present embodiment, the following effects can be obtained.
1) Since the first sheet P1 temporarily waiting in the branch path 25 operates the lower branch claw 19 before the transport to the branch path 25 is completed by the switchback and opens the horizontal transport path 20, The lower branch claw 19 and the second sheet P2 conveyed next do not collide. Therefore, it is not necessary for the image forming apparatus 1 to open an extra sheet between the first sheet P1 and the second sheet P2 so as to avoid interference with the lower branch claw 19. As a result, the first sheet P1 is made to wait on the branch path 25 for the time required for the post-processing of the previous job, and the gap between the second sheet P2 ejected from the image forming apparatus 1 cannot be opened. As a result, it is possible to prevent a reduction in productivity of sheet processing in the image forming system.

2) Since it is not necessary to convey the paper P while spreading the lower branch claw 19 with the conveyance force of the paper P, the first sheet P1 and the second sheet P2 to be prestacked are positioned at the lower branch claw 19 position. The sheet can be conveyed simultaneously with the contact, and as a result, the sheet or the image forming surface of the sheet is not damaged.

3) The pitch between the switchback roller 6 in the horizontal conveyance path 20 and the pre-stack roller 7 in the branch path 25 is normally a pitch that allows conveyance of the minimum paper size, for example, B5 horizontal size. Therefore, when a paper P having a large size, for example, A3 vertical size or a small size, for example, A4 vertical size, is temporarily held in the branch path 25, when the first sheet P1 is conveyed to the branch path 25 by switchback, The switchback roller 6 is opened so that it does not need to be conveyed until it passes through the nip of the switchback roller 6 in the horizontal conveyance path 20, and the lower branch claw 19 can convey the second sheet P2 in this state. The second sheet P2 is conveyed by operating in the state. As a result, when the leading edge P2f of the second sheet P2 and the leading edge P1f of the first sheet P1 are aligned, the nip of the switchback roller 6 can be bound and conveyed to the post-processing tray 8 side. As a result, even with a large size sheet, it is possible to shorten the conveyance time and to minimize the distance between the sheet to be conveyed next, without causing a decrease in productivity.

  Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention, and all of the technical matters included in the technical idea described in the claims are included. The subject of the present invention. The above-described embodiments show preferred examples, but those skilled in the art can realize various alternatives, modifications, variations, and improvements from the contents disclosed in the present specification. These are included in the technical scope described in the appended claims.

  In the present embodiment, the first conveyance path in the claims is the horizontal conveyance path 20, the branching portion is at the branch position 24, the second conveyance path is at the branch path 25, and the first direction is at D2. The second direction is D1, the first transport means is the switchback roller 6, the paper processing device is the paper post-processing device 2, the guiding means is the lower branching claw 19, the control means is the control unit 201, The first transported paper is the first paper P1, the next transported paper is the second paper P2, the rear end of the first transported paper is the reference P1b, and the front end of the paper is the reference In P1f, the branch claw is the lower branch claw 19, the transport gap of the second transport path is L2, the third direction is D1, the second transport means is the prestack roller 7, One transport roller is connected to the pre-stack roller 7 in two directions that can rotate only in the forward direction and only in the reverse direction. Feed rollers for first and second prestack roller 30 and 31, the image forming system to a system consisting of the sheet post-processing apparatus 2 and the image forming apparatus 1 Tokyo, corresponding.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Paper post-processing apparatus (paper processing apparatus)
6 Switchback Roller 7 Pre-Stack Roller 19 Lower Branch Claw 20 Horizontal Transport Path 24 Branch Position 25 Branch Path 30 First Pre-Stack Roller 31 Second Pre-Stack Roller 201 Controller L2 Transport Gap P Paper P1 First Sheet P2 2nd sheet P1b 1st sheet trailing edge P1f 1st sheet leading edge

Japanese Patent No. 3417994 Japanese Patent No. 3617936

Claims (6)

A first conveyance path that is branched by a branching unit and connected to a second conveyance path on which a sheet waits;
First conveying means for conveying a sheet conveyed along a first conveying path in a first direction that is a conveying direction and a second direction that is opposite to the conveying direction;
The first state where both the first conveyance path and the second conveyance path are opened at the branching section, or the first conveyance path is blocked and the second conveyance path is opened second. Guidance means for setting the state and guiding the paper;
When the paper waits, the guide means is set in the second state to transport the paper transported first in the second direction and wait for the paper transported next In the case of transporting together with the previously transported paper , the guide means is set to the first state, and the control means for transporting the paper in the first direction by stacking the paper,
With
The control means is configured such that after the rear end of the paper transported in the second direction passes through the branching portion, the front end of the paper in the first direction has the front end in the first direction. before passing through the branching portion, it is conveyed by then superimposing the sheet to be conveyed is conveyed in the first direction to the paper in the first direction,
The first transport means is composed of a transport roller that is capable of rotating in the forward and reverse directions and located downstream of the branching portion in the first direction. 2 positions of the position where the conveying force is not applied are set,
The second transport unit is provided in the second transport path, and transports the paper in the first direction and a third direction downstream of the second transport path,
The first transport unit and the second transport unit are arranged at an interval smaller than the minimum dimension in the transport direction of the paper to be transported,
The rear end side of the paper in the first direction is nipped by the second transport means when waiting on the second transport path, and the front end side of the paper in the first direction is the first direction. When the first transport unit is out of the nip of the transport unit, the first transport unit maintains a nip state, and when the leading end side of the sheet is nipped by the first transport unit with respect to the first direction. The sheet processing apparatus, wherein the first conveying unit is set in a nip open state . The sheet processing apparatus according to claim 1,
A paper processing apparatus, wherein the leading edge of the first transported paper is overlapped with the leading edge of the next transported paper in the first direction, with the leading edge substantially aligned with respect to the first direction . In the paper processing apparatus according to claim 1 or 2,
The paper processing apparatus according to claim 1, wherein the guide means includes a branching claw that switches a paper conveyance direction by a swinging motion. In the paper conveyance device according to any one of claims 1 to 3,
The sheet processing apparatus, wherein a conveyance gap of the second conveyance path in the branching section is set wider than a conveyance gap of the first conveyance path. The sheet processing apparatus according to any one of claims 1 to 4,
The sheet processing apparatus, wherein the second transport unit includes a single transport roller that can rotate forward and reverse, or two transport rollers that can rotate only in the forward direction and in the reverse direction . An image forming system comprising the sheet processing apparatus according to claim 1 .

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