JP2005324933A - Paper processing device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper processing device capable of functioning in the same manner as in a case where a carrying means for carrying sheet is installed in a pre-stack route even if the carrying means is not installed in the pre-stack route. <P>SOLUTION: This paper processing device comprises a carrying route D guiding paper to a staple tray F, the pre-stack route E branched from the carrying route D and allowing the paper to be temporarily retreated therein, and carrying rollers R4 and R5 carrying the paper in a staple tray F direction and a side reverse to the staple tray F direction. The paper processing device has a function to carry the preceding paper temporarily retreated in the pre-stack route E in the overlapped state thereof with a subsequent paper. The paper processing device also comprises a branch claw 17 guiding the paper to the pre-stack route E when the paper is allowed to flow reversely. The paper is allowed to flow reversely by carrying rollers 4 and 5 installed in the carrying route D, and the paper is retreated to the pre-stack route E in which a carrying function is not set by the branch claw 17 and the carrying rollers R4 and R5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is provided with an image forming apparatus and the like, and a sheet processing apparatus for sorting, binding, stacking, and the like of a sheet-like transfer medium discharged from the apparatus, for example, transfer paper (paper), and the sheet processing apparatus are integrated or separated. The present invention relates to an image forming apparatus provided on a body.

  For example, the invention disclosed in Patent Document 1 is known as this type of technology. This document discloses the following sheet feeding configuration. That is, this document exemplifies an example of a system that intermittently delays sheets in an online printing process. This system necessitates interrupting or delaying the printing of the copy sheet that follows the set when it neats (aligns) the set of previous copy sheets ejected from the printer or copier. It is something that is not. In this example, the output (discharge) path of a printer or copier that is substantially flat or straight is defined by flat upper and lower baffles as in the prior art. In this flat sheet output path, a plurality of output (discharge) feed rollers capable of reversing (reversing) are provided at the downstream end so as to be in front of a module or unit that performs ordering (alignment) and needle fixing. is there. These output rollers also serve as rollers for supply to the compiler unit. A turning gate is provided between the nip of the output roller and the nip of the upstream feed roller, and this gate changes the course of the sheet sent upstream rather than downstream by the reversely rotated output roller. It changes from the main output path that forms the chute to the entrance branched at a certain angle. In the turning chute, a roller capable of rotating in reverse is provided, and the sheet in the chute is always sandwiched between the rollers. The chute is not here for reversing the sheet, nor is the sheet reversed in this.

The preceding sheet is in a normal sheet discharge roller (also serving as an entrance roller of a tidy device (compiler)) and slightly protrudes. This normal feeding operation continues until the end of the preceding sheet passes through the entrance of the turning chute, which is the path for the buffer that intersects the main output path. Thereafter, the output roller rotates in the reverse direction, and the preceding sheet is rapidly fed upstream. At the same time, the turning gate turns to the lower sheet path side, and the succeeding sheet guides the preceding sheet to the chute before reaching the gate. Then, the gate is lifted to the original position as soon as the preceding sheet is caught in the nip of the roller. The following sheet tries to pass over the preceding sheet in the chute. Therefore, the following sheet moves straight as usual and moves without being disturbed by the output roller. At that time, all the rollers move so as to advance the sheet downstream, and the preceding sheet is fed from the chute and becomes the lower side of the sheet along with the succeeding sheet in the main output path. Both sheets are reliably moved separately by the rollers, but they move together through the main sheet output path towards the nip of the output rollers. Both sheets reach the output roller and are fed forward in a state where they overlap each other.
JP-A-7-002417

  The patent document discloses a technique in which a preceding sheet is temporarily retracted by a chute and is conveyed while being superposed on a subsequent sheet. In this technology, as described above, the reverse chute roller is provided in the turning chute, and the sheet in the chute is always sandwiched between the rollers, and the sheet is retracted and held according to the rotation direction of the roller. And unloading (sending out) were possible.

  Conventionally, it is necessary to provide a roller in the chute for retracting the sheet in this way, and to drive it at the same timing, which complicates the mechanism and control.

  The present invention has been made in view of the situation of the prior art as described above, and the object thereof is to function in the same manner as in the case where a roller for conveying a sheet is not provided in a chute for retracting the sheet. An object of the present invention is to provide a sheet processing apparatus and an image forming apparatus that have a simple structure and are low in cost.

  In order to achieve the object, the first means includes a first conveyance path for guiding the sheet to the processing tray, and a second conveyance path that branches from the first conveyance path and temporarily retracts the sheet. And a transport means for transporting the paper in the direction opposite to the processing tray side and the processing tray side, the preceding paper temporarily retracted in the second transport path is followed. In a paper processing apparatus having a function of transporting the paper in a superimposed manner, the paper processing device includes switching means for guiding the paper to the second transport path when the paper is made to flow backward, and is provided in the first transport path. The sheet is caused to flow backward by the conveyance unit, and the sheet is retracted by the switching unit and the conveyance unit to the second conveyance path in which a conveyance function is not set.

  The second means is a paper processing apparatus based on the same premise as the first means, the switching means for guiding the paper to the second transport path when the paper is made to flow backward, and the paper to flow backward. When the preceding sheet is guided to the second conveying path by the switching unit, the preceding sheet is held by the conveying unit provided in the first conveying path downstream of the switching unit in the sheet conveying direction. And a control means for stopping the conveying means and waiting until the succeeding sheets are overlaid.

  The third means is characterized in that in the first or second means, there is provided a guide member for guiding the paper carried into the second transport path when the paper is made to flow backward.

  The fourth means is any one of the first to third means, wherein the transport means is a first transport means provided on the upstream side of the paper transport from the switching means, and a paper transport from the switching means. And a second conveying means provided on the downstream side in the direction, wherein the reverse flow of the paper is performed by the second conveying means.

  The fifth means is characterized in that, in the fourth means, the guide member is driven by the same drive source as the second paper conveying means.

  A sixth means is characterized in that, in the third means, a driving force is not applied to the guide member.

  7. A sheet processing apparatus according to claim 1, wherein the seventh means is the first or second means, wherein the second transport path is curved.

  The eighth means is a paper processing apparatus based on the same premise as the first means, the switching means for guiding the paper to the second transport path when the paper is made to flow backward, and the paper to flow backward. When the preceding paper is guided to the second transport path by the switching means, after the preceding paper has been detached from the transport means provided in the first transport path downstream of the switching means in the paper transport direction. Control means for stopping the conveying means, holding the paper in contact with the preceding weight by the weight of the preceding paper, and waiting until the following paper is overlaid. Features.

  A ninth means is characterized in that, in the eighth means, the second transport path is formed in a substantially linear shape.

  The tenth means is any one of the first to ninth means, wherein the control means causes the leading edge of the succeeding sheet to be superimposed on the preceding sheet and then transported to the processing tray side. It is characterized by.

  The eleventh means is characterized in that, in the tenth means, at least two sheets are conveyed to the processing tray side.

  The twelfth means is characterized in that the image forming apparatus is provided with the sheet processing apparatus according to any one of the first to eleventh means as a single body or as a separate body.

  In the following embodiments, the processing tray is the staple processing tray F, the first transport path is the transport path D, the second transport path is the prestack path E, and the transport means is the transport roller 2. , 7, 9, 10, 11 (R1, R2, R4, R5) and the first and second transport motors, the switching means to the branching claw 17, the control means to the CPU 360, and the first transport means to The transport rollers 2, 7 (R1, R2), the second transport means are transport rollers 9, 10, 11 (R4, R5), the guide members are transport rollers 8 (R3), and the paper processing device is paper post-processing The image forming apparatus corresponds to the apparatus PR, and the image forming apparatus corresponds to the code PR.

  According to the present invention, a simple and low-cost sheet processing apparatus and image formation that can function in the same way as when a sheet conveying unit is not provided in the second conveying path. An apparatus can be provided.

The best mode for carrying out the present invention will be described below with reference to the drawings.
1. First Embodiment <Overall Configuration>
FIG. 1 is a diagram illustrating a system configuration of an image forming system including a sheet post-processing apparatus and an image forming apparatus as a sheet processing apparatus according to an embodiment of the present invention. In FIG. Part of the device is shown.

  In FIG. 1, a sheet post-processing device PD is attached to a side portion of the image forming apparatus PR, and a sheet (recording medium) discharged from the image forming apparatus PR is guided to the sheet post-processing device PD. The sheet passes through a conveyance path A having a post-processing unit (in this embodiment, a punch unit 100 as a punching unit) for performing post-processing on a single sheet, and passes through conveyance rollers 2, 3, and 4 to the upper tray 201. Alignment and stapling, etc. via the conveying path B, the conveying path C that leads to the shift tray 202 through the conveying path B, the conveying rollers 2, 5 and 6, the conveying roller 7, the rotation guide 8, the conveying rollers 9, 10 and the staple discharge roller 11. The branching claws 15 and the branching claws 16 respectively distribute to the conveyance path D leading to the processing tray F (hereinafter also referred to as a staple processing tray). The tray surface on which the sheets of the staple processing tray F are stacked is inclined so that the downstream side in the conveyance direction of the sheets discharged from the staple discharge roller 11 is upward, and the inclination angle is inclined with respect to the gravity direction. The minimum angle is set so as not to interfere with the middle folding plate 74 on the lower side of the surface and the driving mechanism thereof and the mechanism such as the end surface binding stapler S1.

  The paper guided to the staple processing tray F through the transport paths A and D and subjected to alignment, stapling, and the like in the staple processing tray F is guided to the shift tray 202 by the branch guide plate 54 and the movable guide 55. The sheet is configured to be distributed to a processing tray G to be folded (hereinafter also referred to as a middle folding processing tray), and the sheet subjected to folding or the like in the middle folding processing tray G is guided to the lower tray 203 through the conveyance path H. . Further, a branching claw 17 is disposed in the conveyance path D, and is held in a state shown in the figure by a low load spring (not shown). After the rear end of the sheet passes through the conveyance path 9, the conveyance rollers 9, 10 and the staple discharge roller 11 is configured such that at least the conveying roller 9 is reversed to guide the trailing edge of the sheet to the sheet accommodating portion E so that the sheet is retained and conveyed while being overlapped with the next sheet. By repeating this operation, it is possible to convey two or more sheets in a superimposed manner.

  In the conveyance path A common to the upstream of the conveyance path B, the conveyance path C, and the conveyance path D, an inlet sensor 301 that detects a sheet received from the image forming apparatus, an inlet roller 1, a punch unit 100, and a punch downstream thereof. The waste hopper 101, the conveying roller 2, the branching claw 15 and the branching claw 16 are sequentially arranged. The branch claw 15 and the branch claw 16 are held in the state shown in FIG. 1 by a spring (not shown), and when the solenoid (not shown) is turned on, the branch claw 15 rotates upward and the branch claw 16 rotates downward. The paper is distributed to the conveyance path B, the conveyance path C, and the conveyance path D.

  When guiding the paper to the conveyance path B, the branching claw 15 is in the state of FIG. 1 and the solenoid is OFF. When guiding the paper to the conveyance path C, the branching claw 15 is turned on by turning on the solenoid from the state of FIG. When the paper is guided to the transport path D, the branch claw 16 is in the state of FIG. 1, the solenoid is OFF, and the branch claw 15 is in the state of FIG. By turning on the solenoid, the solenoid is turned upward.

  In this paper post-processing apparatus, punching (punching unit 100), paper alignment + edge binding (jogger fence 53, edge binding stapler S1), paper alignment + saddle stitching (jogger fence 53, saddle stitching stapler) is performed on the paper. S2), paper sorting (shift tray 202), center folding (folding plate 74, folding roller 81), and the like can be performed.

  In this embodiment, the image forming apparatus PR performs optical writing on an image forming medium such as a photosensitive drum based on the input image data to form a latent image on the surface of the photosensitive drum, and the formed latent image is displayed. This is an image forming apparatus using a so-called electrophotographic process in which toner is developed, transferred to a recording medium such as paper, fixed, and discharged, and the image forming apparatus using the electrophotographic process itself is well known, so the details here Description and illustration of this configuration are omitted. In this embodiment, an image forming apparatus using an electrophotographic process is illustrated. However, a system using a known image forming apparatus such as an inkjet or a printing machine and a printing machine (printer) may also be used. Needless to say.

<Stipple processing tray>
In the processing tray F that performs paper alignment and stapling processing, the paper guided to the processing tray F by the staple discharge roller 11 is sequentially stacked on the tray surface 66. In this case, alignment in the vertical direction (paper conveyance direction) is performed by the tapping roller 12 for each sheet, and alignment in the horizontal direction (paper width direction orthogonal to the sheet conveyance direction) is performed by the jogger fence 53. Thereafter, the end-face stitching stapler S1 is driven by a staple signal from the control device 350 between job breaks, that is, between the last sheet of the sheet bundle and the first sheet of the next sheet bundle, and the binding process is performed. The sheet bundle subjected to the binding process is immediately sent to the shift paper discharge roller 6 by the discharge belt 52 having the discharge claw 52a, and is discharged to the shift tray 202 set at the receiving position. The discharged sheet bundle is brought closer to the lower end side of the shift tray 202 by the gathering roller 13.

  The home position of the discharge claw 52 a is detected by a discharge belt HP sensor 311, and this release belt HP sensor 311 is turned on / off by a discharge claw 52 a provided on the discharge belt 52. Two discharge claws 52a are arranged at opposing positions on the outer periphery of the discharge belt 52, and the sheet bundle accommodated in the processing tray F is moved and conveyed alternately. Further, if necessary, the discharge belt 52 is reversely rotated, and the sheet bundle accommodated in the processing tray F on the back surface of the discharge claw 52a facing the discharge claw 52a waiting to move the sheet bundle. The tips in the transport direction may be aligned.

  Further, the drive shaft of the discharge belt 52 driven by a discharge motor (not shown) has the discharge belt 52 and its drive pulley arranged at the center of alignment in the paper width direction, and the discharge roller 56 is arranged and fixed symmetrically. The peripheral speed of the discharge roller 56 is set to be faster than the peripheral speed of the discharge belt 52. The tapping roller 12 is given a pendulum motion by a tapping SOL (not shown) around the fulcrum 12 a and intermittently acts on the sheet fed to the staple processing tray F so as to abut the sheet against the rear end fence 51. The hitting roller 12 rotates counterclockwise. The jogger fence 53 is driven via a timing belt by a jogger motor (not shown) capable of forward and reverse rotation, and reciprocates in the paper width direction.

  The end-face stitching stapler S1 is driven via a timing belt by a forward / reversely movable stapler moving motor (not shown), and moves in the sheet width direction in order to bind a predetermined position of the sheet edge. A stapler movement HP sensor for detecting the home position of the end face binding stapler S1 is provided at one end of the moving range, and the binding position in the paper width direction is controlled by the amount of movement of the end face binding stapler S1 from the home position. The

  The saddle stitching stapler S2 is disposed such that the distance from the trailing edge fence 51 to the needle striking position of the saddle stitching stapler S2 is equal to or longer than a distance corresponding to half of the conveyance direction length of the maximum sheet size that can be saddle stitched. Two are arranged symmetrically with respect to the alignment center in the width direction. Further, the saddle stitching stapler S2 includes a needle portion, and is divided into two units of a stitcher (driver) unit S21 for driving out the needle and a clincher unit S22 for bending the needle, and the stitcher unit S21 conveys the processing tray F. It is arranged on the road D side. In the figure, reference numeral 310 denotes a paper presence / absence sensor that detects the presence / absence of paper on the staple processing tray F.

  The sheet bundle that has undergone saddle stitching in the staple processing tray F is folded in the middle of the sheet. This middle folding is performed in the middle folding processing tray G. For this purpose, it is necessary to transport the bound sheet bundle to the middle folding processing tray G. In this embodiment, a sheet bundle deflecting unit is provided on the most downstream side in the conveyance direction of the staple processing tray F, and conveys the sheet bundle to the middle folding processing tray G side.

  The sheet bundle deflection mechanism includes a branch guide plate 54 and a movable guide 55. The branch guide plate 54 is provided so as to be swingable in the vertical direction around the fulcrum 54a, and a rotatable pressure roller 57 is provided on the downstream side thereof, and is pressed against the discharge roller 56 side by a spring. The branch guide plate 54 is driven by a cam, and the movable guide plate 55 is driven by a link.

<Folding processing tray>
The middle folding processing tray G includes a lower guide plate 91 and an upper guide plate 92 installed in the vertical direction, and a folding plate 74 that reciprocates in the direction perpendicular to the guide plates 91 and 92 is provided at the folding position. It has been. Since the folding position varies depending on the paper size, the lower guide plate 91 is provided with a movable rear end fence 73 for making the central portion of the paper face the folding plate 74, and the paper is conveyed on both guide plates 919 and 92. Is performed by transport rollers 71 and 72. A sheet bundle folded in half by the folding plate 74 and the folding roller 81 passes through the conveyance path H and is discharged to the lower tray 203 by the discharge roller 83.

<Control device>
As shown in FIG. 2, the control device 350 includes a microcomputer having a CPU 360, an I / O interface 370, and the like. Each switch of the control panel of the image forming apparatus PR main body, the entrance sensor 301, and the upper discharge sensor 302 , A shift paper discharge sensor 303, a paper presence / absence sensor 310, a discharge belt home position sensor 311, a bundle arrival sensor 321, a movable rear end fence HP sensor 322, a folding section passage sensor 323, a paper surface detection sensor 330, and the like. The data is input to the CPU 360 via the I / O interface 370.

  Based on the input signal, the CPU 360 moves a tray raising / lowering motor for the shift tray 202, a discharge guide plate opening / closing motor for opening / closing the opening / closing guide plate, a shift motor for moving the shift tray 202, and a tapping roller motor for driving the tapping roller 12. , Solenoids such as hitting SOL, a conveyance motor for driving each conveyance roller, a sheet discharge motor for driving each sheet discharge roller, a discharge motor for driving the discharge belt 52, a stapler moving motor for moving the end surface binding stapler S1, and end surface binding The driving of an oblique motor that rotates the stapler S1 obliquely, a jogger motor that moves the jogger fence 53, and the like is controlled. A pulse signal of a not-shown staple conveyance motor that drives the motor staple discharge roller is input to the CPU 360 and counted, and the hitting SOL and the jogger motor are controlled according to this count. The punch unit 100 also performs drilling according to instructions from the CPU 360 by controlling the clutch and the motor.

  The sheet post-processing device PD is controlled by the CPU 360 executing a program written in a ROM (not shown) while using a RAM (not shown) as a work area. In addition, the program data is downloaded from a server via a network or from a recording medium such as a CD-ROM or SD card to a storage medium such as a hard disk device (not shown) via a recording medium driving device instead of or in addition to the ROM. It can also be used after being rolled or upgraded.

<Operation>
FIG. 3 is a schematic configuration diagram for explaining the operation of the sheet post-processing apparatus according to the present invention, and FIGS. 4 to 7 temporarily store sheets in a transport path (hereinafter referred to as a prestack path) E that temporarily stores sheets. It is operation | movement explanatory drawing of the prestack operation | movement which carries out re-transporting.

  In FIG. 3, the punch unit 100 is omitted from FIG. 1, and only the pre-stack operation and the path for discharging from the staple processing tray F to the shift tray 202 are schematically illustrated. In the paper transport system, transport rollers R1 and R2 on the upstream side of the branch claw 17 and transport rollers R4 and R5 on the downstream side of the branch claw 17 are independently driven by first and second transport motors (not shown). The In FIG. 3, the conveyance rollers upstream of the branching claw 17 are shown as two rollers R1 and R2, and the conveyance rollers downstream of the branching claw 17 are shown as R4 and R5, whereas in FIG. Three transport rollers 1, 2, and 7 are installed on the upstream side of the claw 17, and three transport rollers 9, 10, and 11 are installed on the downstream side (these are also arranged on the upstream side with respect to the branch claw 17). The transport rollers 1, 2 and 7 are one motor (first transport motor), and the transport rollers 9, 10, and 11 arranged on the downstream side are the other motor (second transport motor). 3), the operation functions in the arrangement of the conveying rollers in FIG. 3, and will be described below with reference to the schematic diagram in FIG. Note that it is essential that the distance between the transport rollers R1, R2, R4, and R5 be set to an interval that can deliver the paper.

  The transport rollers R4 and R5 transport the paper transported from the transport path A to D in the reverse direction (transport in the direction of reversing toward the receiving port from the image forming apparatus PR, hereinafter referred to as “reverse flow”). Can do. This reverse flow is performed by reversing the rotation direction of the second transport motor. It is also possible to use a clutch instead of the reverse rotation of the motor to rotate the gears in the reverse direction and reverse the rotation.

  The conveyance path D is provided with a branching claw (switching claw) 17 for guiding the sheet to the prestack path E when the sheet is made to flow backward so that it overlaps with the next sheet fed through the conveyance path D. Then, it is possible to re-convey papers that match the pre-stack path E, convey the sheets in a stacked state, and discharge them to the staple processing tray F. In this case, the number of sheets to be reversed is changed by information (control signal or the like) sent from the image forming apparatus PR main body in the sheet post-processing apparatus 2.

  More specifically, the sheet output from the image forming apparatus PR enters the sheet post-processing apparatus PD, and is transported by transport rollers R1 and R2 driven by a first transport motor (not shown). The bifurcating claw 17 is rotated counterclockwise in the figure by force, passes through the conveyance path D secured thereby, and the staple processing tray F by the conveyance rollers R4 and R5 driven by the second conveyance motor (not shown). (In the direction of arrow a).

  The sheet conveyed into the staple processing tray F falls by its own weight in the direction of the arrow b, and the conveyance direction is aligned by the rear end fence 51. After the trailing edge of the sheet is detected by the entrance sensor 301, when the time expected to complete the alignment of the sheet conveyance direction by the trailing edge fence 51 has elapsed, the jogger fence (alignment fence) 10 causes the sheet in the direction orthogonal to the sheet conveyance direction. Alignment is performed. By repeating the operations of the trailing edge fence 51 and the jogger fence 53, the sheets are aligned one by one, and a large number of sheets are aligned.

  When the alignment of the final sheet is completed, the aligned sheet bundle is bound by the stapler S1, the discharge belt 52 in the staple processing tray F rotates in the direction of the arrow c, and the sheet bundle is discharged by the discharge claw 52a attached to the discharge belt 52. The lower end of the sheet is pushed up to discharge the sheet bundle from the staple processing tray F in the direction of arrow d. The sheet bundle is discharged and stacked on the shift tray 202 by the discharge roller 6a and the driven roller 6b. The shift tray 202 has a mechanism that moves up and down according to the number of stacks. The driven roller 6b is rotatably attached to the conveyance guide plate 6c, and the conveyance guide plate 6c can swing around the fulcrum 6c so that the same conveyance force can be obtained even if the thickness of the sheet bundle to be conveyed changes. The sheet bundle is pressed against the discharge roller 6a by the weight of the conveyance guide plate 6c. The above is the operation in the case of one copy.

  In this embodiment, the branch claw 17 guided to the prestack path E is driven to open the prestack path E side, and the transport rollers 7, 9, and 11 are reversed to guide the paper to the prestack path E side. it can. At this time, the re-conveyance start timing of the sheet retreated to the prestack path E is determined based on the detection timing at the entrance sensor 301 at the leading end of the sheet output from the image forming apparatus PR side. Thus, the timing for reversing the sheet to be conveyed based on the detection of the trailing edge of the sheet and retracting it to the prestack path E side is determined.

  When the sheet conveyed from the image forming apparatus PR is retracted to the prestack path E and is conveyed to the side of the staple processing tray F while being overlapped with the next conveyed sheet, first, as shown in FIG. The sheet P1 is conveyed by forward rotation of the conveying rollers R1 and R2 (hereinafter, the direction of conveyance toward the staple processing tray F side is referred to as normal rotation, and the direction of conveyance away from the staple processing tray F is referred to as reverse rotation). As described above, the leading end of the paper P1 pushes the back surface of the branching claw 17 and advances the transport path D downstream in the transport direction. When the rear end of the sheet transports the sheet by a preset number of pulses from the timing when the entrance sensor 301 is cut, the rotation guide R3 and the transport rollers R4 and R5 that have been rotated as shown in FIG. Then, the paper transport direction is reversed and the paper flows backward. At that time, the branching claw 17 closes the conveyance path D side and opens the prestack conveyance path E side as shown in FIGS. 4 and 5. As a result, as shown in FIG. 5, the rear end portion of the sheet P1 that has flowed backward is guided to the prestack path E side along the branching claw 17, and the transport roller is left with a predetermined amount of the front end portion of the sheet in the transport path D. R4 and R5 stop and enter a retreat state.

  In this state, the next sheet P2 is conveyed from the image forming apparatus PR side by the forward rotation of the conveyance rollers R1 and R2, and as shown in FIG. When the leading edge of the sheet P2 is conveyed upstream from the conveying roller R4 to a position of, for example, 10 mm, the conveying rollers R4 and R5 that have been stopped as shown in FIG. 6 start to rotate forward. When two sheets of double feed are sufficient, the paper is discharged to the staple processing tray F as it is, and when three or more sheets are double fed, the transport rollers R4 and R5 are reversed at the same timing as in FIG. Then, the two sheets are transported to the prestack path E side in a state of being overlapped, and stopped. Then, waiting for the conveyance of the third sheet, when the third sheet is conveyed as in the case of the two sheets P2, three sheets are stacked and sent to the staple processing tray F side.

  At this time, the leading sheet P1 of the job is re-conveyed while being nipped by the nip of the conveying roller R4, so that the leading edge of the leading sheet P1 of the job is the leading edge of the second sheet P2 of the job. Two sheets are discharged to the staple processing tray F at the same time in a preceding state. In the case of three or more sheets, the paper is discharged in a state where the leading edge of the sheet conveyed later is always retracted from the leading edge of the previously conveyed sheet. The discharged sheet bundle is rotated in the direction of arrow b by reversely rotating the discharge belt 52 provided in the staple processing tray F, and then discharged on the side facing the discharge claw 52a waiting to move the sheet bundle. On the back surface of the claw 52a, the leading end of the sheet bundle accommodated in the staple processing tray F is hit, and the sheet is mechanically dropped to the rear end fence 51 to eliminate the deviation in the transport direction and align the sheet bundle.

  Using such a pre-stack path E, after stacking sheets on the pre-stack path E, the multi-feed is performed at the first part, the second part, the second part, the third part, etc. This is a time when the following paper cannot be discharged onto the stapling processing tray F at the same timing as the paper in the middle of the section because post-processing such as stipple is performed on the preceding section unless pre-stacking. At this time, when the image forming operation is waited until the processing on the side of the staple processing tray F is completed on the image forming apparatus PR side, the image forming efficiency is lowered. As for the copy interval with the first sheet, an image is formed at the same timing as the image formation timing in the case of the same portion, and is continuously sent to the paper post-processing apparatus at the same interval. At that time, a signal is sent from the image forming apparatus PR. The signal from the image forming apparatus PR includes the number of transported sheets, the transporting speed, and the processing mode information. When the sheet post-processing apparatus PD receives these signals, the number of sheets for transporting the paper in the prestack path E, the transporting A point (timing) for increasing the conveying speed of the rollers R1, R2 or R4, R5, a speed increasing linear velocity, a point (timing) for starting a reverse flow, and a reverse flow linear velocity are determined.

The above operation is summarized as follows.
The transport rollers R1 and R2 rotate in the arrow direction (forward rotation direction), and the first sheet of the second copy is transported. The first sheet P1 is transported at an increased transport speed based on detection information from the entrance sensor 301. Further, after the entrance sensor 301 detects the trailing edge of the paper P1, the control timing is taken by a pulse count, a timer or the like, and the paper is conveyed to a position where it flows backward. Next, when it is necessary to reverse the sheet by a signal from the main body of the image forming apparatus 1, the conveying rollers R4 and R5 are rotated in the reverse direction, and the sheet P1 is conveyed in the reverse direction by the branching claw 17, and at a predetermined timing. Stop with slowdown control. Thereafter, the second paper P2 is transported in the forward direction by the transport rollers R1 and R2, the transport rollers R4 and R5 are rotated forward, and the second paper P2 is transported in a state of being superimposed on the first paper P1. If the staying number at that time is less than the staying number sent by the signal from the image forming apparatus PR main body, the same operation as the first sheet is repeated, and two sheets are repeated until the staying number received from the main body is reached. The sheets are discharged to the staple processing tray F in the stacked state.

  In this embodiment, the rotation guide 8 is rotatably supported and does not receive a driving force. However, the rotation guide 8 is conveyed by the same drive motor (second conveyance motor) as the conveyance rollers R4 and R5. It can also be configured to drive at the same peripheral speed as the rollers R4 and R5. In this case, a member that presses the sheet against the rotation guide 8 is not necessary, and the rotation guide 8 and the sheet move relatively at the same linear velocity, and therefore it can be considered that there is no frictional force between the two. The rotation guide 8 has only a simple guide function.

  As described above, according to the present embodiment, since the sheet conveying unit is not required in the prestack path E, the configuration is simplified, and the post-processing is performed without reducing the processing efficiency (CPM) on the image forming apparatus PR main body side. be able to.

  Further, when the pre-stack path E is curved by rotating the rotation guide 8 at a speed equivalent to the conveyance speed of the sheet by the conveyance rollers 4 and 5, no frictional force is generated between the rotation guide 8 and the sheet. Thus, even in a curved conveyance path, the reverse flow of the sheet can be reliably performed by the conveyance roller 4.

  Further, by using the driving force of the conveying rollers 4 and 5 as the driving force of the rotation guide 8, a driving source for the rotation guide 8 is not required, and the above function can be exhibited at low cost.

2. Second Embodiment FIG. 8 is a schematic configuration diagram for explaining the operation of a sheet post-processing apparatus according to a second embodiment of the present invention. FIGS. 9 to 12 are sheet post-processing apparatuses according to the second embodiment. FIG. 13 is a flowchart showing a control procedure of the operation. FIG. 13 is a diagram illustrating the operation of the pre-stack operation in which the paper is temporarily stored in the pre-stack path E in FIG. In the following description, the same reference numerals are assigned to the same parts as those in the above-described embodiment, and the overlapping description is omitted.

  In this embodiment, the rotation guide R3 is omitted from the first embodiment shown in FIG. 3, and the sheet is detected on the conveyance path D at a position upstream of the conveyance roller R4 and close to the conveyance roller R4. A sensor 304 is provided. In the second embodiment, as shown in FIG. 8, the pre-stack path E is provided so as to be inclined obliquely upward from the swinging end of the branch claw 17 so that the leading edge of the sheet is always located on the side of the transport roller R4 due to gravity. It is composed. The other parts are configured in the same manner as the paper post-processing apparatus PD shown in FIG.

  In the sheet post-processing apparatus PD configured as described above, the sheet conveyed from the image forming apparatus PR is retracted to the pre-stack path E and overlapped with the next conveyed sheet to the side of the staple processing tray F. When transporting, first, as shown in FIG. 9, the paper P1 is transported by the forward rotation of the transport rollers R1 and R2, and the front end of the paper P1 pushes the back surface of the branching claw 17 as described above to move along the transport path D. Proceed downstream in the transport direction. Then, the conveyance of the paper P1 is monitored, and the conveyance rollers R4 and R5 that have been rotated as shown in FIG. As shown in FIG. 5, the paper P1 is reversely rotated, the transport direction of the paper P1 is reversed, and the paper P1 flows backward (step S103). At that time, the branching claw 17 closes the conveyance path D side and opens the pre-stack conveyance path E side as shown in FIG. As a result, as shown in FIG. 10, the rear end portion of the paper P <b> 1 that has flowed backward is guided along the branch claw 17 to the prestack path E side. At this time, the paper detection sensor 304 detects the leading edge (paper trailing edge) of the paper in the backward flow direction (step S104), and the paper P1 is caused to flow backward by a predetermined pulse from this detection timing (step S105), and the leading edge of the paper P1. When the sheet passes through the nip of the pair of conveying rollers R4, the backflow operation of the sheet P1 is stopped (step S106), and the retracted state is set. Then, the transport rollers R4 and R5 are also stopped. After passing through the nip of the conveying roller R4, the timing to stop the conveying roller R4 is when a predetermined pulse has passed since the sheet P1 flows backward and the sensor 304 is turned on. It is preset at the timing of exiting the nip.

  In this state, the next sheet P2 is conveyed from the image forming apparatus PR side by the forward rotation of the conveying rollers R1 and R2, and the next sheet P2 is conveyed to the leading end of the sheet P1 retracted in the prestack path E as shown in FIG. The transport rollers R4 and R5 that have been stopped when the leading edge of the paper P2 is overlaid (steps S107 and S108) start to rotate forward (step S109). When two sheets can be double-fed, the sheet is discharged from the state of FIG. 11 to the staple processing tray F as it is, and when three or more sheets are double-fed, the transport roller is at the same timing as in FIG. R4 and R5 are reversed, and are transported to the prestack path E side in a state where two sheets are overlapped as shown in FIG. Then, waiting for the conveyance of the third sheet, when the third sheet is conveyed as in the case of the two sheets P2, three sheets are stacked and sent to the staple processing tray F side. When the paper detection sensor 304 detects the trailing edge of the paper (step S110), the second transport motor (paper discharge motor) rotates forward as it is when paper is discharged and further overlaps with the next paper. Reverse.

  Other parts that are not particularly described are configured in the same manner as the first embodiment described above and function in the same manner.

  According to this embodiment, since the paper position is set using gravity when the paper is retracted, the apparatus can be configured at low cost.

3. Third Embodiment In the second embodiment, the paper P1 retracted to the pre-stack path E is in a state of slipping out of the nip of the transport roller R4, but is retracted with the paper P1 being sandwiched in the nip. It can also be made. This embodiment will be described as a third embodiment.

  That is, in the retracted state shown in FIG. 10, the next paper P2 is kept in the nip of the transport roller R4 with the leading end of the paper P1 protruding from the nip of the transport roller R4 by a predetermined amount. At the time of arrival, as described above, the paper P1 can be overlapped with the leading edge of the paper P1 advanced from the nip of the transport roller R4 and transported as shown in FIG. In this case, in the second embodiment, since the paper P1 is positioned at the nip position of the transport roller R4 due to the action of gravity, the transport roller R4 is caught in the nip when the transport roller R4 performs superposed transport for some reason. However, the conveyance failure may occur, but the sheet P1 does not leave the nip of the conveyance roller R4. Therefore, the conveyance failure does not occur.

  Here, the preceding paper is described as P1, and the paper that follows and overlaps the paper P1 is described as P2. However, the same applies to the third paper, and in this case, the preceding papers P1 and P2 overlap. In this state, the sheet is nipped by the nip of the conveying roller 4 and retreated.

  This embodiment also operates according to the procedure of the flowchart shown in FIG. The difference from the second embodiment is the reverse rotation amount (reverse pulse amount) of the second transport motor in step S105. That is, in the second embodiment, since the sheet passes through the nip of the transport roller R4 to the upstream side, the motor pulse is set to be sufficient to slip out. However, in the third embodiment, the transport roller R4 of the transport roller R4 is set. Since it is held in a state where it is sandwiched by a predetermined amount in the nip, the reverse pulse amount of the second transport motor is set to be small by an amount corresponding to the amount sandwiched by the nip and protruding downstream in the transport direction.

  Other parts not specifically described are configured in the same manner as the first and second embodiments described above and function in the same manner.

  According to the present embodiment, since the paper position when the paper is retracted is set by the conveyance roller that reversely feeds the paper, the apparatus can be configured at low cost.

1 is a diagram illustrating a system configuration of an image forming system including a sheet post-processing apparatus and an image forming apparatus as a sheet processing apparatus according to an embodiment of the present invention. 1 is a block diagram illustrating a control configuration of an image forming system according to an embodiment of the present invention. It is the schematic for demonstrating operation | movement of the paper post-processing apparatus which concerns on embodiment of this invention. FIG. 4 is an operation explanatory diagram under the schematic configuration of FIG. 3, showing a state where a sheet is conveyed and is in a conveyance path D; FIG. 5 is an operation explanatory diagram under the schematic configuration of FIG. 3, showing a state in which the preceding paper that was in the conveyance path D in FIG. 4 is reversely fed and retracted to the prestack path. FIG. 4 is an operation explanatory diagram under the schematic configuration of FIG. 3, showing a state in which a subsequent sheet is conveyed along a conveyance path D. FIG. 4 is an operation explanatory diagram under the schematic configuration of FIG. 3, showing a state in which a succeeding sheet is superimposed on a preceding sheet and re-conveyed. It is the schematic for demonstrating operation | movement of the paper post-processing apparatus which concerns on the 2nd Embodiment of this invention. FIG. 9 is an operation explanatory diagram under the schematic configuration of FIG. 8, showing a state where a sheet is conveyed and is in a conveyance path D; FIG. 9 is an operation explanatory diagram under the schematic configuration of FIG. 8, showing a state in which a preceding sheet in the conveyance path D is reversely fed and retracted to the prestack path. FIG. 9 is an operation explanatory diagram under the schematic configuration of FIG. 8, showing a state in which a subsequent sheet is conveyed to the conveyance path D. FIG. 9 is an operation explanatory diagram under the schematic configuration of FIG. 8, showing a state in which a succeeding sheet is superimposed on a preceding sheet and re-conveyed. It is a flowchart which shows the control procedure in 2nd Embodiment.

Explanation of symbols

1, 2, 7, 9, 10, 11 (R1, R2, R4, R5) Conveying rollers (pair)
8 (R3) Rotation guide 17 Branch claw 301 Entrance sensor 360 CPU
D Conveying path E Pre-stacking path F Stipple processing tray M1 First conveying motor M2 Second conveying motor PD Paper post-processing apparatus PR Image forming apparatus

Claims (12)

A first transport path for guiding paper to the processing tray;
A second conveyance path that branches off from the first conveyance path and temporarily retracts the paper;
Conveying means for conveying the paper in the direction opposite to the processing tray side and the processing tray side;
A sheet processing apparatus having a function of superimposing and transporting a preceding sheet that has been temporarily retracted to the second transport path with a following sheet,
Switching means for guiding the paper to the second transport path when the paper is made to flow backward,
The paper is caused to flow backward by the transport means provided in the first transport path, and the paper is retracted by the switching means and the transport means to the second transport path where a transport function is not set. Characteristic paper processing apparatus. A first transport path for guiding paper to the processing tray;
A second conveyance path that branches off from the first conveyance path and temporarily retracts the paper;
Conveying means for conveying the paper in the direction opposite to the processing tray side and the processing tray side;
A sheet processing apparatus having a function of superimposing and transporting a preceding sheet that has been temporarily retracted to the second transport path with a following sheet,
Switching means for guiding the paper to the second transport path when the paper is made to flow backward;
When the sheet is caused to flow backward and the preceding sheet is guided to the second conveying path by the switching unit, the preceding unit is conveyed by the conveying unit provided in the first conveying path downstream in the sheet conveying direction from the switching unit. Control means for stopping the conveying means in a state where the paper to be held is held, and waiting until the following paper is overlaid,
A sheet processing apparatus comprising:   The sheet processing apparatus according to claim 1, further comprising a guide member that guides a sheet carried into the second conveyance path when the sheet is caused to flow backward. The transport means comprises a first transport means provided on the upstream side of the paper transport with respect to the switching means, and a second transport means provided on the downstream side of the paper transport direction with respect to the switching means,
4. The sheet processing apparatus according to claim 1, wherein the backward flow of the sheet is performed by a second transport unit. 5.   The sheet processing apparatus according to claim 4, wherein the guide member is driven by the same drive source as the second sheet conveying unit.   The sheet processing apparatus according to claim 3, wherein no driving force is applied to the guide member.   The sheet processing apparatus according to claim 1, wherein the second conveyance path is curved. A first transport path for guiding paper to the processing tray;
A second conveyance path that branches off from the first conveyance path and temporarily retracts the paper;
Conveying means for conveying the paper in the direction opposite to the processing tray side and the processing tray side;
A sheet processing apparatus having a function of superimposing and transporting a preceding sheet that has been temporarily retracted to the second transport path with a following sheet,
Switching means for guiding the paper to the second transport path when the paper is made to flow backward;
When the sheet is caused to flow backward and the preceding sheet is guided to the second conveying path by the switching unit, the preceding unit moves from the conveying unit provided in the first conveying path downstream in the sheet conveying direction from the switching unit. Control means for stopping the conveying means after the sheet to be released is held, holding the paper in contact with the conveying means by the weight of the preceding paper, and waiting until the following paper is superimposed; ,
A sheet processing apparatus comprising:   9. The sheet processing apparatus according to claim 1, wherein the second transport path is formed in a substantially linear shape.   10. The sheet processing according to claim 1, wherein the control unit conveys the leading end portion of the following sheet to the preceding sheet and then transports the sheet to the processing tray side. 11. apparatus.   The sheet processing apparatus according to claim 10, wherein at least two sheets are conveyed to the processing tray side.   12. An image forming apparatus comprising the sheet processing apparatus according to claim 1 as a single unit or as a separate body.

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