JP4279705B2 - Image forming system - Google Patents

Description

The present invention is provided integrally or separately in an image forming apparatus such as a copying machine, a printer, or a printing machine, and performs predetermined processing such as sorting, stacking, binding, and saddle stitching on an image-formed sheet (recording medium). binding to an image forming system including a sheet processing equipment of exhaust paper with the image forming apparatus performs.

  FIG. 13 shows an example of a sheet post-processing apparatus that has been conventionally used. In the drawing, the sheet output from the image forming apparatus 1 enters the post-processing apparatus 2, passes through the position of the sensor S 1, and is conveyed to the processing tray 18 by the conveying roller 4, the conveying roller 5, the conveying roller 7, and the conveying roller 8. The The conveyed paper falls by its own weight in the direction of arrow B, and the conveyance direction is aligned by the rear end fence 11. The trailing edge of the sheet is detected by the sensor S2 in advance, and the width direction is aligned by the alignment fence 10 after a time during which the sheet conveyance direction can be aligned. By repeating this operation, a large number of sheets are aligned one by one. When the alignment of the final sheet is completed, the aligned sheet bundle is bound by the stapler 12, the discharge belt 14 in the processing tray 18 is rotated in the direction of arrow C, and the discharge claw 13 attached to the discharge belt 14 adjusts the alignment unit. The sheet bundle is discharged from the direction 18 to the arrow D direction. The sheet bundle is discharged to the tray 3 by the discharge roller 15 and the driven roller 16 and stacked. The tray 3 has a mechanism that moves up and down according to the number of stacks.

  The driven roller 16 is attached to a conveyance guide plate 17, and the conveyance guide plate 17 can be rotated around a fulcrum 17a so that the same conveyance force can be obtained even if the thickness of a sheet bundle to be conveyed changes. The discharge roller 15 is pressed by the weight of the conveyance guide plate 17. The above is the operation in the case of one copy.

  In the case of two or more copies, the image forming apparatus 1 staples the first copy of the first set on the processing tray 18 and finishes discharging the first copy of the second set on the processing tray 18 when the first copy is discharged. The copy interval with the first sheet of the next part is set, and the first sheet of the next part is copied.

  As described above, conventionally, it is necessary to stop the copy operation in order to secure time for stapling between the sections, resulting in a decrease in productivity.

  In order to cope with the deterioration of the productivity, there is also a technology for preventing or reducing the decrease in productivity by temporarily retaining the first sheet of the second copy in the machine to increase the apparent interval between the portions. Proposed. As this type of technology, for example, the invention disclosed in Patent Document 1 or 2 is known.

  For example, in Patent Document 1, in a finisher that stacks sheets discharged from an image forming apparatus and performs stapling processing, a stacking tray that aligns and stacks sheets, a first transport path that transports sheets to the stacking tray, A stapling unit that performs a stapling process on a bundle of sheets stacked on the stacking tray, a paper folding unit that performs a paper folding process on the paper, a sheet is conveyed to the paper folding unit, and the first conveying path A second transport path that feeds in the middle, and when the staple processing is being performed on the sheet bundle of the previous set, the first sheet of the next set is transported through the second transport path and 2 sheets Disclosed is an invention in which a sheet of eyes is transported through the first transport path, and the first and second sheets are merged and overlapped in the middle of the first transport path and accommodated on the stacking tray. Has been.

Further, in Patent Document 2, in the sheet post-processing apparatus that stacks sheets conveyed from the image forming apparatus on an intermediate stacker, aligns them, binds them with a stapler, and then discharges the sheet bundle onto a sheet discharge tray. In order to form the next sheet bundle after the bound sheet bundle, the first sheet and the second sheet sent from the image forming apparatus in the sheet conveyance path before being introduced into the intermediate stacker. An invention is disclosed that includes conveying means for superimposing the sheets and conveying them to the intermediate stacker, driving means for driving the conveying means, and control means for controlling timing of the driving means.
JP-A-8-301508 Japanese Patent Laid-Open No. 9-235069

  In the prior art, when the number of staying is increased, the apparent interval increases, and there is a great merit that it can cope with a high-speed machine. However, after a plurality of sheets are retained, it is necessary to transport them in an overlapped state, and in the case of such a post-processing apparatus, since the transport path is generally complicated, the transport limit becomes large. There is a demerit.

  Therefore, it has been proposed that the number of staying sheets is limited by the setting information and the sheet feeding tray. However, in this case, the number of staying sheets is changed based on information determined by the system, and production is unnecessarily performed. May cause a decline in sex. For example, when the thick paper is set in the paper feed tray, if the number of staying sheets is limited, the system cannot detect the degree of the thick paper, and the restriction is applied based on the maximum paper thickness that can be passed. However, the frequency with which the user uses the maximum paper thickness of the system is often not so high, and if a little thick paper is used, the productivity decreases more than necessary, which is not preferable for the user.

  In addition, when transporting paper with heavy load such as thick paper, it is necessary to reduce the staying number of sheets. However, since the time for post-processing such as stipple is not reduced, the staying number is less than the set value. If it was changed, the process would not be in time and had to be stopped once.

  Further, in the above-described prior art, it is necessary to cause the sheet to stay in the sheet post-processing apparatus due to a change in the processing speed (CPM-COPY PER MINUTE) on the image forming apparatus main body side. However, the number of sheets to stay depends on the CPM of the image forming apparatus main body, the number of processed sheets, and the processing mode. Also, when determining whether to discharge or stay by the paper presence / absence detection sensor provided in the processing tray for temporarily holding the paper in order to perform processing such as stapling in the paper post-processing apparatus, the processing mode for the small number of sheets Depending on the presence or absence of the paper in the processing tray, there may be a case where the number of sheets is larger than the number of sheets to be processed and the conveyance becomes impossible. Therefore, it is necessary to change the number of sheets to stay depending on the main body CPM, the number of processed sheets, and the processing mode. Further, as the CPM of the image forming apparatus main body is increased in speed, the sheet post-processing apparatus needs to be in time for the main body CPM.

  In addition, when the staying paper is transported again, the amount of misalignment with the next paper affects the alignment accuracy after paper discharge from the processing tray, so the interval of misalignment needs to be constant. However, if the sheet being conveyed at high speed is stopped immediately, the stop position may be deviated from the target position due to inertial force.

  SUMMARY OF THE INVENTION The present invention has been made in view of such a state of the art, and an object thereof is to provide a sheet processing apparatus and an image forming system that can maintain the best productivity and are easy to use.

First means for achieving the above object, an image formation with an image forming apparatus for forming a visible image on the sheet, and a sheet processing apparatus for discharging a sheet conveyed from the image forming apparatus as the sheet bundle In the system , a sheet conveyance path through which the sheet received from the image forming apparatus is conveyed, and a sheet branched from the sheet conveyance path, and conveyed in the reverse direction along the sheet conveyance path by the switching unit, An intermediate tray for stacking and retaining one or more sheets, and a control unit for transporting sheets to the intermediate tray side based on information from the image forming apparatus and changing the number of sheets to be retained in the intermediate tray ; , wherein the retention number is changed, when staying number inputted from the external input device is less than the number set in advance, the image forming apparatus before the number And it transmits to the sheet processing apparatus, to the last sheet parts being processed and controls to be wider than before the change the first sheet interval of the parts to be next processed.

According to a second means, in the first means, the image forming apparatus performs the next process from the last sheet of the processing section based on the difference between the staying sheet number input from the external input device and the preset staying sheet number. The paper interval at the head of the copy is changed.

The third means is characterized in that, in the first means, the image forming apparatus changes the leading sheet interval of the next processing section from the last sheet of the processing section according to the size of the sheet to be retained.

According to the present invention, since the sheet processing apparatus has to change the sheet staying number of sheets by the information from the image forming apparatus main body, it can maintain the best productivity, to provide ease of use Ige imaging system it can.

The best mode for carrying out the present invention will be described below with reference to the drawings.
<First Embodiment>
FIG. 1 is a schematic diagram showing an outline of a system configuration of an image forming system including a sheet post-processing apparatus and an image forming apparatus according to the first embodiment of the present invention. In FIG. 1, the image forming system according to the present embodiment includes an image forming apparatus 1 and a sheet post-processing apparatus 2, and a sheet after image formation is performed by the image forming apparatus 1 performs post-processing such as stapling. It is conveyed to the paper post-processing device 2.

  The sheet post-processing apparatus 2 includes a processing tray 18, a main conveyance path E that guides the sheet to the processing tray 18, sheet conveyance means (conveyance rollers) 4, 5, 6, 7, and 8, and alignment that aligns the sheets. Means (alignment fence) 10 and binding means (stapler) 12 for binding the bundle of sheets are provided. Further, the sheet post-processing apparatus 2 includes a discharge unit (discharge belt) 14 that discharges the sheet bundle bound by the binding unit 12 from the processing tray 18, a stack tray 3 that stacks the discharged sheet bundle, and the stack tray. 3 is provided with a discharge means (discharge roller) 15 for discharging the sheet bundle, and the conveyance rollers 6, 7, and 8 can reverse the sheet to be conveyed (reverse to the receiving port side from the image forming apparatus). It is the composition.

  The main transport path E has switching means 9 (switching claw) for guiding the paper to another transport path F when the paper is made to flow backward so that it overlaps with the next paper fed through the main transport path E. In addition, the sheet evacuated to another transport path F is transported again in a state where a plurality of sheets are stacked, and can be discharged to the processing tray 18. In this case, the number of sheets to be reversed is changed by the information sent from the main body of the image forming apparatus 1 in the paper post-processing apparatus 2.

  More specifically, the sheet output from the image forming apparatus 1 enters the sheet post-processing apparatus 2 and is transported by the transport roller 4 and the transport roller 5 driven by a transport motor (not shown). The switching claw 9 is rotated counterclockwise, passes through a transport path (main transport path) E secured thereby, and is transported by a transport roller 7 and a transport roller 8 driven by a transport motor (not shown). It is conveyed to. The sheet conveyed into the processing tray 18 falls by its own weight in the direction of arrow B, and the conveyance direction is aligned by the rear end fence 11. The trailing edge of the sheet is detected by the sensor S2 in advance, and the width direction is aligned by the alignment fence 10 after a time during which the sheet conveyance direction can be aligned. By repeating this operation, a large number of sheets are aligned one by one.

When the final sheets are aligned, the aligned sheet bundle is bound by the stapler 12, the discharge belt 14 in the processing tray 18 rotates in the direction of arrow C, and the discharge claw 13 attached thereto rotates the processing belt 18 from the processing tray 18 in the direction of arrow D. Release the stack of paper. The sheet bundle is discharged and stacked on the stack tray 3 by the discharge roller 15 and the driven roller 16. The stack tray 3 has a mechanism that moves up and down according to the number of stacks. The driven roller 16 is attached to a conveyance guide plate 17 and is configured to be rotatable around a fulcrum 17a so that the same conveyance force can be obtained even if the thickness of a sheet bundle to be conveyed changes. 17 is configured to pressurize the discharge roller 15 by its own weight.
The above is the operation in the case of one copy.

  FIG. 2 is an operation explanatory view showing the operation of FIG. 1, and shows a state where the sheet is conveyed and is in the main conveyance path. FIG. 3 is an operation explanatory view showing a state in which the first sheet in the main conveyance path in FIG. As described with reference to FIG. 1, the first sheet G is conveyed from the image forming apparatus 1 to the sheet post-processing apparatus 2 and is reversely fed from the state in the main conveyance path E (FIG. 2) to other conveyances. It enters the path F from the rear end (FIG. 3). FIG. 4 is a schematic view showing a state in which the second sheet is sent out to the main transport path E in the state of FIG. FIG. 5 is a schematic diagram showing a state in which the first and second sheets are conveyed and are in the main conveyance path. FIG. 6 is a schematic view showing a state in which the first and second sheets in the main conveyance path in FIG. 5 are reversely fed and the rear end portion enters the other conveyance path. When the first sheet G is in the state shown in FIG. 3, the second sheet H is conveyed to the main conveyance path E in FIG. At this time, the sensor S2 senses the leading edge of the second paper H and is transported to the main transport path E together with the first paper G in the other transport path F (FIG. 5).

  FIG. 7 is a schematic view showing a state in which the third sheet is conveyed to the main conveyance path in the state of FIG. FIG. 8 is a schematic view showing a state in which the first, second and third sheets are simultaneously conveyed to the processing tray through the main conveyance path.

  When the number of copies is two or more, the image forming apparatus 1 continuously copies to the sheet post-processing apparatus 2 with the same interval as the other interval between the last sheet of the preceding section and the first sheet of the next section. Send it in. At that time, a signal is sent from the image forming apparatus 1. The signal from the image forming apparatus 1 includes the number of sheets to be conveyed, the conveyance speed, and processing mode information. The number of sheets, the acceleration point, and the acceleration that the sheet is retained by receiving these signals by the sheet post-processing apparatus 2. The linear velocity, reverse flow point, and reverse linear velocity are determined.

  With reference to FIG. 7 and FIG. 8, the backflow method of the third paper I will be described. When the first and second sheets G and H enter the other conveyance path F as shown in FIG. 6, the third sheet I passes from the image forming apparatus 1 to the sheet post-processing apparatus 2 via the conveyance roller 4. When the prestack sensor S2 is turned on, the sheets stacked on the intermediate tray (the other conveyance path F) are once conveyed from the intermediate tray to the conveyance path.

  The rear end of the third sheet I is conveyed to the backflow point based on the information that the sensor S1 is turned off, and the state shown in FIG. 5 is obtained. In the reverse flow method, similarly to the method in which the first and second papers G and H are made to flow backward, the transport rollers 6, 7, and 8 are reversely rotated and simultaneously conveyed to the intermediate tray (the other transport path F) while being reversely rotated. It becomes like 6. The stop is performed based on information that the leading edge of the third sheet turns off the sensor S2. At this time, the first paper G and the second paper H are separated and stopped, and the second paper H is advanced in the paper discharge direction from the leading edge of the first paper G.

  When the third sheet I is conveyed as shown in FIG. 7 and the leading edge of the sheet turns on the sensor S2, the first and second sheets that are stacked by rotating the conveying rollers 6, 7, and 8 in the forward direction are stacked. G and H also start conveyance, and the three sheets are simultaneously discharged to the processing tray 18 as shown in FIG. At this time, the paper is discharged so that the leading edge of the third paper I precedes.

  In the above operation, the transport rollers 4 and 5 are rotated in the direction of the arrow, and the first sheet of the second copy is transported. The first sheet G is conveyed at an increased conveyance speed based on the detection information of the sensor S1. Further, the control timing is determined by a pulse count, a timer, or the like after the sensor S1 detects the trailing edge of the sheet, and the sheet 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 6, 7, and 8 are reversed, and the sheet is conveyed by the switching claw 9 as shown in FIG. When the paper edge is detected by the sensor S2, slow down control is performed to stop the paper. Next, the second paper H is transported in the forward direction by the transport rollers 4 and 5, and when the leading end is detected by the sensor S 2, the transport rollers 6, 7 and 8 are rotated and the second paper H is stacked. Transport. If the staying sheet number at that time is smaller than the staying sheet number sent by the signal from the image forming apparatus 1, the same operation as that for the first sheet is repeated and repeated until the staying sheet number received from the main body is reached. The paper is discharged to the processing tray 18 in the state of being overlaid.

FIG. 9 is a block diagram showing a control configuration of the image forming system according to the present embodiment that performs the control as described above.
In the figure, the control device 31 of the paper post-processing device 2 is composed of a microcomputer having a CPU 32, an I / O interface 33, and the like, each switch of the control panel of the image forming apparatus 1 main body, the inlet sensor SN1, and the paper discharge. Signals from the sensor SN2 and other sensors are input to the CPU 32 via the I / O interface 33. The CPU 32 controls various motors and solenoids based on the input signals. Further, for example, when the paper post-processing apparatus 2 is provided with a punch unit 26 as paper processing means, the punch unit 26 also performs punching according to an instruction from the CPU 32 by controlling a clutch and a motor. The image forming apparatus 1 main body is provided with a CPU 1 a that controls the image forming apparatus 1 main body and transmits necessary information (control signal) to the control device 31 side of the sheet post-processing apparatus 2. A signal from the image forming apparatus 1 in this embodiment is output from the CPU 1a or based on an instruction from the CPU 1a.

  The image forming apparatus 1 and the sheet post-processing apparatus 2 are controlled by the CPU 1a and CPU 32 respectively executing programs written in a ROM (not shown) while using a RAM (not shown) as a work area. .

FIG. 10 is a flowchart showing the operation procedure of the paper post-processing operation of the image forming system according to the present embodiment.
In this operation procedure, by pressing a start key (not shown) of the image forming apparatus 1, the sheet post-processing apparatus 2 receives information on the sheet processing mode and the conveyance speed. The processing mode is roughly divided into a staple mode and a shift mode. In the present embodiment, the operation and effect are obtained in the staple mode. Further, when the conveyance to the first processing tray 18 is completed, information on the paper size and the number of sheets conveyed from the image forming apparatus 1 is received.

  First, the second copy (second paper) is started (step S1), and the control device 31 receives the processing mode, paper size, and linear velocity information from the main body of the image forming apparatus 1 (step S2). Based on these pieces of information, it is determined whether or not the sheet needs to stay in the transport path (step S3). If staying is necessary, the next step S4 is executed. In step S4, the staying number, the speed increasing point, the speed increasing linear velocity V1, the back flow point, and the back flow linear velocity V2 are determined. Here, the speed increasing point is a point for increasing the speed of the paper because the configuration of the paper post-processing apparatus 2 needs to widen the interval between the last paper of the preceding part and the leading paper of the next part. Although the speed increasing linear speed is described in terms of speed increasing points, it is the speed at which the paper is accelerated and conveyed in order to widen the paper interval when stacking the paper. The backflow point is a point at which the paper flows back and is constant.

  Like the acceleration point, in the flowchart, since the control is based on the ON signal of the inlet sensor S1, the distance conveyed to the backflow point differs depending on the paper size. Therefore, it is necessary to determine the backflow point and the backflow linear velocity V2. On the other hand, when the determination is made based on the off signal of the inlet sensor S1, the conveyance distance is constant, and therefore is omitted here. The reverse flow linear velocity is a conveyance speed when the paper is made to flow backward.

  The number of stacked sheets (the number of staying sheets) is determined according to the time when the interval between the last sheet of the preceding section and the leading sheet of the next section is increased and the image forming apparatus does not wait for image formation. In addition, when the number of conveyed sheets is two, only one sheet can be stacked. Therefore, even when the image forming apparatus 1 is waiting for image formation, the second sheet is discharged to the processing tray 18.

  When each element is determined in step S4, it is determined whether or not the inlet sensor S1 is on (step S5). If it is on, driving of the paper discharge motor is started (step S6). Next, it is determined whether or not the acceleration point has been reached (step S7). If the acceleration point has been reached, the conveyance motor and the discharge motor are increased to the conveyance speed V2 (step S8). Next, it is determined whether or not the number of received sheets is larger than the number of staying sheets (step S9), and if it is larger, the sheet is discharged to the processing tray 18 (step S10). If the number of accepted sheets is smaller than the number of staying in step S9, it is determined whether or not the backflow point has been reached (step S11), and if reached, the conveyance is stopped (step S12). In this case, the point at which the paper flows backward is constant. Next, reverse flow conveyance is started at the conveyance speed V2 (step S13). It is determined whether or not the sensor S2 is off (step S14). If it is off, the discharge motor is decelerated (step S15). The paper discharge motor is stopped (step S16), and it is determined whether or not the sensor S2 is turned on by the next paper (step S17). If it is turned on, the carry motor is operated to start re-feed and step S7. Return to.

  With the above operation, it is possible to cope with changes in the processing mode and the number of processed sheets, and it is possible to perform post-processing compatible with high-speed machines without reducing productivity.

<Second Embodiment>
In this embodiment, the number of sheets to be stacked is changed according to the binding mode. Since the configuration of the image forming system itself is the same as that of the first embodiment described above, the same reference numerals are assigned to the same components, and duplicate descriptions are omitted.

  The stapler 12 can be moved to each binding position by the configuration as shown in FIG. 11. In the case of one-point binding, the stapler 12 stays at the designated location and performs the stippling process. When a plurality of bindings are designated, first, the plurality of bindings are performed by moving to a first binding position, waiting, and appropriately moving. In other words, since one-point binding and multiple binding are performed with one stapler, inevitably longer processing time is required for multiple binding. In this case, a description will be given on the assumption that a sufficient processing time can be secured by stacking two sheets in the case of one-point binding and superposing and conveying four sheets at the time of two-point binding.

  When the final sheets are aligned, the aligned sheet bundle is bound by the stapler 12, the discharge belt 14 in the processing tray 18 rotates in the direction of arrow C, and the discharge claw 13 attached thereto moves from the processing tray 18 in the direction of arrow D. Release the stack of paper. The sheet bundle is discharged and stacked on the tray 3 by the discharge roller 15 and the driven roller 16.

  When the number of copies is two or more, the image forming apparatus 1 normally makes copies to the sheet post-processing apparatus 2 continuously with the same copy interval between the last sheet of the copy and the first copy of the next copy as in other cases. Send it in. Since the processing operations for the second and subsequent copies are the same as those in FIGS. 2 to 8 in the first embodiment, redundant description is omitted.

  When the superimposition number limit is set in the service setting mode or the user setting mode when transported in this manner, it is compared with the superposition number preset in the binding mode to be executed. The smaller number is given priority and the number of overlaps is set. In this case, the image forming apparatus is instructed to increase the paper discharge interval in order to compensate for the processing time that cannot be ensured by the number of overlapped sheets.

  If the number of overlapping sheets increases, it is possible to secure the binding processing time and prevent a decrease in productivity. However, if the number of overlapping sheets increases, there is a possibility that the sheet conveyance load increases and the conveyance quality decreases. When the number of binding locations is small, it is possible to secure a sufficient binding processing time with a small number of overlays. Therefore, when the number of binding locations is small, the number of overlaps is small, and when the number of binding locations is large, overlay is performed accordingly. By using the number of sheets, it is possible to minimize a decrease in conveyance quality while preventing a decrease in productivity.

  When transporting a plurality of sheets in a stacked manner, if thick paper is mixed, the transport quality may be significantly deteriorated. In order to prevent this, it is conceivable to limit the number of stacked sheets systematically based on information such as paper feed tray setting information and normal tray or manual feed tray. Although this method seems to be easy to use at first glance, if the system is limited, it will inevitably be a safe setting number, even if it is a little thick paper, it will be the same setting as ultra thick paper, limiting the number of sheets more than necessary As a result, productivity is reduced more than necessary. This is not very preferable from the viewpoint of usability. In the first place, the number of sheets used in general offices is limited. In the present invention, the number of sheets to be superimposed can be set according to the sheets, so that it is easy to use and the reduction in productivity can be minimized.

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

<Third Embodiment>
In this embodiment, the control is changed when the number of sheets to be overlaid is changed. Since the configuration of the image forming system itself and the conveyance state of the paper are the same as those in the first embodiment, equivalent parts are not included. The same reference numerals are assigned, and duplicate descriptions are omitted.

  That is, in this embodiment, when the number of sheets to be overlapped is changed and the input information is less than the preset number of sheets to be overlapped, the number of sheets is transmitted from the image processing apparatus 1 to the sheet post-processing apparatus 2 side, and The image forming process of the image forming apparatus is controlled so that the interval between the last sheet of the section being processed and the leading sheet interval of the section to be processed next is wider than before the change.

As shown in FIG. 4, when the second sheet is conveyed by the conveying rollers 4 and 5 and the front end of the sheet is detected by the sensor S2, the conveying rollers 6, 7, and 8 rotate in the direction of the arrow in FIG. Transport in a stacked state. When this operation is repeated and the sheets are overlapped and the set number of sheets is overlapped, the overlapped sheets are simultaneously discharged to the processing tray 18 as shown in FIG. At this time, as for the number of sheets to be overlapped, one-point binding and a plurality of bindings are performed with one stapler. In this case, two sheets are overlapped in the case of one-point binding, and four sheets are overlapped and conveyed in the case of two-point binding, so that a sufficient processing time can be ensured. .

  In the case of one-point binding, assuming that there is no overlap, that is, the number of staying sheets is 0 and an external input device such as an operation unit of the image forming apparatus 1 is set, the image forming apparatus 1 recognizes the set number of sheets and the sheet post-processing apparatus 2 side Tells the number of stays to 0. Thereafter, the image processing apparatus 1 uses the difference between the sheet size and the staying number (in this case, 1-1 = 0 sheets × the sheet interval for each sheet) and the leading sheet interval of the section to be processed next. And the control is changed so that the sheet is conveyed to the sheet post-processing apparatus 2 side with an interval. Similarly, in the case of two-point binding, if two sheets are overlapped, the image forming apparatus 1 recognizes the set number of sheets and informs the sheet post-processing apparatus 2 of the number of staying sheets 2. Thereafter, the leading sheet interval of the next processing section is determined from the final sheet set by the sheet size and the difference number of stays (in this case, 4-2 = 2 sheets × the sheet interval for each sheet), and the interval is calculated. The control is changed so that it is opened and transported to the post-processing side.

FIG. 12 is a flowchart showing a control procedure at this time. Further details will be described with reference to this flowchart.
In this process, first, it is determined whether or not there is a job capable of staying in a sheet (step S21), and it is determined whether or not the number of staying sheets is changed only when the job is capable of staying in a sheet (step S22). If there is a change, the staying sheet number information is transmitted to the sheet post-processing apparatus 2 (step S23). If the set sheet number is smaller than the default (step S24), the difference between the sheet size and the default set staying sheet number is confirmed. (Step S25). Next, the time between jobs is reset to the time obtained by multiplying the number of sheets remaining between the paper sheets (step S26), and when the last sheet of the job is reached (step S27), the time between jobs is the reset time. (Step S28), the next job is started. If NO is determined in steps S21, S22, and S24, the default time between jobs is set (step S29), and the next job is started.

  When transporting a plurality of sheets in a superimposed manner as described above, if thick paper is mixed, the transport quality may be significantly deteriorated. In order to prevent this, the number of overlapped sheets is limited, and as a result, there is a gap between sheets more than necessary or once stopped, and the productivity is considerably lowered. However, in the present embodiment, since the minimum sheet interval setting is performed based on the binding mode, the sheet size, and the prestack difference number from the default, it is possible to maintain the conveyance quality and suppress the productivity from being lowered more than necessary.

  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.

  As described above, according to the first to third embodiments, the sheet processing apparatus changes the number of sheets staying (number of sheets to be reversed) according to a signal from the image forming apparatus main body. Regardless of this, it is possible to prevent the malfunction of paper retention.

  Also, by making the paper faster than the main body acceptance line speed when the paper flows backward, the first paper can be reliably pre-stacked before the second paper is detected by the sensor S2, and the high speed machine can also be used. Yes.

  In addition, since the paper is stopped while being slowed down when the paper is stopped at the staying position, it is possible to stop at the target position by eliminating the inertia force of the roller, and the interval between the next paper is constant. Can be kept in.

  In addition, since the number of overlapping sheets can be set in accordance with the paper, it is easy to use and the reduction in productivity can be minimized.

  Furthermore, since the minimum sheet interval setting is performed by the binding mode, the sheet size, and the pre-stack difference number from the default, it is possible to maintain the conveyance quality and suppress the productivity from being lowered more than necessary.

1 is a diagram illustrating a schematic configuration of an image forming system according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a state where a sheet is conveyed and is in a main conveyance path in the explanation operation of FIG. 1. FIG. 3 is a schematic diagram illustrating a state where the first sheet in the main conveyance path in FIG. 2 is reversely fed and is in another conveyance path. FIG. 4 is a schematic diagram illustrating a state in which a second sheet is transported to a main transport path in the state of FIG. 3. FIG. 6 is a schematic diagram illustrating a state where first and second sheets are conveyed and are in a main conveyance path. FIG. 6 is a schematic diagram illustrating a state in which the first sheet in the main conveyance path in FIG. 5 is reversely fed and is in another conveyance path. FIG. 7 is a schematic diagram illustrating a state in which a third sheet is transported to the main transport path in the state of FIG. 6. FIG. 6 is a schematic diagram illustrating a state in which first, second, and third sheets are simultaneously conveyed to a processing tray through a main conveyance path. 1 is a block diagram illustrating an outline of a control configuration of an image forming system according to an embodiment of the present invention. 6 is a flowchart illustrating a control procedure of the sheet post-processing apparatus according to the first embodiment. It is a perspective view which shows the structure of the stapler which concerns on 2nd Embodiment. 10 is a flowchart illustrating a control procedure of an image forming apparatus according to a third embodiment. It is a figure which shows schematic structure of the image forming system which concerns on a prior art example.

Explanation of symbols

1 Image forming apparatus 1a, 31 CPU
2 Paper post-processing device 4, 5, 6, 7, 8 Transport roller 9 Switching claw S1, S2 Sensor E Main transport path (paper transport path)
F Other transport path (paper transport path)
G 1st paper H 2nd paper I 3rd paper

Claims (3)

And an image forming apparatus for forming a visible image on a sheet, an image forming system including a sheet processing apparatus for discharging a sheet conveyed from the image forming apparatus as a sheet bundle,
A paper transport path through which paper received from the image forming apparatus is transported;
An intermediate tray that branches from the paper transport path, transports the paper transported along the paper transport path by the switching means in the reverse direction, and retains the paper;
Control means for transporting sheets to the intermediate tray side based on information from the image forming apparatus and changing the number of sheets retained in the intermediate tray ;
Equipped with a,
When the staying sheet number is changed and the staying sheet number input from the external input device is less than the preset sheet number, the image forming apparatus transmits the sheet number to the sheet processing apparatus and An image forming system , characterized in that control is performed so that a leading sheet interval of a section to be processed next from a last sheet is wider than before the change . The image forming apparatus changes the leading sheet interval of the next processing section from the last sheet of the processing section based on the difference between the staying sheet number input from the external input device and a preset staying sheet number. The image forming system according to claim 1. Wherein the paper-size image forming apparatus to be retained, the image forming system according to claim 1, in which the last sheet parts being processed and changes the first sheet interval of the parts to be next processed.

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