JP2012128167A - Sheet processing device and image forming system - Google Patents

Abstract

To provide a sheet processing apparatus that can cope with many types of sheets and can improve productivity.
A sheet processing apparatus includes: a conveying unit configured to convey a sheet; and the conveyance of the sheet is stopped, and the sheet is held in a stopped state for a predetermined stabilization time at a position where the sheet is stopped. A control unit 501 is provided for controlling the conveying unit so that the sheet conveyance direction is reversed and the sheet is conveyed in the reverse direction after the stable time has elapsed. The control unit 501 sets the stabilization time based on the sheet information indicating the sheet characteristics. For example, the stabilization time is set shorter as the sheet size becomes smaller.
[Selection] Figure 9

Description

  The present invention relates to a sheet processing apparatus that performs conveyance control for reversing the conveyance direction of a sheet, and an image forming system including the sheet processing apparatus.

  An image forming apparatus such as a digital multi-function peripheral (MFP) having a function of punching an image-formed sheet (generally paper) is known. In such an image forming apparatus, for example, the sheet conveyance direction is reversed before perforating the sheet, and the skew of the sheet is corrected by abutting the end of the sheet against the skew correction member. Perforation can be performed at various positions (see, for example, Patent Document 1).

  FIG. 13 is a timing chart when the sheet conveying direction is reversed in the conventional image forming apparatus. In the conventional image forming apparatus, the sheet conveyed in the forward direction from the upstream side toward the downstream river is stopped at the stop position. Regardless of the type of sheet, such as whether it is thick paper or thin paper, large or small, the sheet is kept for a certain period of time (hereinafter referred to as “stable time”) until vibration due to the sheet or roller is stabilized. Hold in a stopped state. Thereafter, the sheet is conveyed in the reverse direction from the downstream river toward the upstream side, and the skew of the sheet is corrected by abutting the trailing edge of the sheet against the skew correction member. Thus, the punching position accuracy is ensured by performing punching processing on the sheet by the punching device after correcting the light shielding of the sheet.

  The reason why the sheet is stopped by providing the stabilization time in this way is as follows. That is, when the sheet being conveyed is decelerated or stopped, the paper itself has an inertial force, so that a mechanical load for conveying the sheet increases due to a speed change. Here, since the stop position of the sheet is usually constant, if the sheet is rapidly decelerated in order to shorten a series of processing time from image formation to punching, the load is further increased.

  In addition, when the sheet being conveyed is decelerated or stopped, the load for conveying the sheet is also great due to the natural vibration of the stepping motor that is the driving motor for conveying the sheet and the inertial force of the sheet and the sheet conveying roller itself. Become. Furthermore, vibration when the phase of the driving current of the stepping motor is switched becomes noticeable when the rotational speed of the stepping motor is extremely slow.

  In this way, there is a possibility that reverse conveyance that reverses the conveyance direction of the sheet in a state where the load is increased and the stepping motor step out. Therefore, the operation is stopped by setting the time until the sheet, the sheet conveying roller shaft, the drive motor and the like are stabilized to be stable so that the step-out does not occur regardless of the type of the sheet.

JP 2008-213962 A

  However, in recent years, with the development of papermaking technology, it has become possible to easily obtain a wide variety of sheets such as thinner paper, thicker paper, special paper, and the like. It is required to support many sheet types. There is also a demand for an image forming apparatus having high productivity (that is, a large number of sheets that can be processed per unit time).

  Here, for example, if the stabilization time is set based on the case of large-size and thick paper, the stabilization time is shorter than the set stabilization time in the case of a small-size sheet or a thin-thick sheet. Therefore, image formation is performed under conditions with low productivity.

  In order to improve productivity, for example, it is necessary to narrow the interval between sheets discharged after image formation. For this purpose, since the next sheet is conveyed downstream when the sheet is reversed and conveyed, it is necessary to shorten the stabilization time during which the sheet is stopped. That is, as in the conventional case, in reverse conveyance control in which a sheet is stopped with a constant stabilization time regardless of the type of paper, it is extremely difficult to achieve both compatibility with many types of sheets and improvement in productivity. .

  An object of the present invention is to provide a sheet processing apparatus that can cope with many types of sheets and can improve productivity.

  In the sheet processing apparatus according to the present invention, a conveying unit that conveys a sheet, and a sheet conveyed in the forward direction by the conveying unit are stopped, and a predetermined stabilization time is set at a position where the sheet is stopped, Control means for holding the sheet and controlling the conveying means so that the conveying direction of the sheet is reversed and conveyed in the reverse direction after the stable time has elapsed, and the control means includes: The stabilization time is set longer as the load increases when the forward conveyance of the sheet is stopped and conveyed in the reverse direction based on sheet information indicating characteristics.

  According to the present invention, the sheet stabilization time during reverse conveyance control is changed according to the sheet type. As a result, it is possible to deal with many types of sheets and improve productivity.

1 is a cross-sectional view illustrating a schematic configuration of an image forming system including a sheet processing apparatus according to an embodiment of the present invention. It is sectional drawing which shows the structure of the sheet processing apparatus which concerns on embodiment of this invention. It is a figure which shows the structure and operation | movement of the punch unit which the sheet processing apparatus which concerns on embodiment of this invention has. It is another figure which shows the structure and operation | movement of a punch unit which the sheet processing apparatus which concerns on embodiment of this invention has. It is another figure which shows the structure and operation | movement of a punch unit which the sheet processing apparatus which concerns on embodiment of this invention has. FIG. 2 is a control block diagram of the image forming system in FIG. 1. 3 is a flowchart of switchback control executed in the image forming system in FIG. 1. It is an example of the table used in order that the sheet processing apparatus control part of a sheet processing apparatus may set stop time. 6 is a timing chart illustrating a relationship between a sheet size and a stabilization time when performing switchback control of a sheet. It is a figure which shows the state which the entrance sensor detected that the front-end | tip of the sheet | seat entered the sheet processing apparatus. It is a figure which shows the state which stopped the sheet | seat for switchback. FIG. 5 is a diagram illustrating a state in which the sheet conveyance direction is reversed and the trailing edge of the sheet is abutted against a trailing edge stopper member. 6 is a timing chart of reverse conveyance control for reversing the sheet conveyance direction in a conventional image forming apparatus.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Here, an image forming system including the sheet processing apparatus according to the present embodiment will be described.

<Overall configuration of image forming system>
FIG. 1 is a cross-sectional view illustrating a schematic configuration of an image forming system including a sheet processing apparatus according to an embodiment of the present invention. This image forming system generally includes an image forming apparatus 300, an automatic document feeder 500 and a sheet processing apparatus 100.

  The automatic document feeder 500 irradiates the document surface with light while automatically feeding the documents one by one, reads the reflected light with a photoelectric conversion element such as a CCD line sensor, and forms an analog signal as an image signal. Output to the control unit of the device.

  In the image forming apparatus 300, first, an analog signal output from the photoelectric conversion element is converted into a digital signal. Based on the obtained digital signals, electrostatic latent images of respective colors are formed on the yellow, magenta, cyan, and black photosensitive drums 914a, 914b, 914c, and 914d, respectively. The electrostatic latent image is developed with each color toner, and toner images are formed on the photosensitive drums 914a, 914b, 914c, and 914d. On the other hand, an image forming (printing) sheet is fed from one of the cassettes 900a to 900d in the image forming apparatus 300 toward the photosensitive drum 914a, and toner images are formed in the order of the photosensitive drums 914a, 914b, 914c, and 914d. It is directly transferred to the sheet. The sheet on which the toner image has been transferred is conveyed to a fixing device 904, and the fixing device 904 fixes the toner image on the sheet and sends it to the sheet processing apparatus 100. Next, the sheet processing apparatus 100 will be described in detail with reference to FIG.

<Schematic structure of sheet processing apparatus>
FIG. 2 is a cross-sectional view illustrating a configuration of the sheet processing apparatus 100. Here, the sheet processing apparatus 100 is connected to the image forming apparatus 300 so as to take in sheets discharged from the image forming apparatus 300. However, the sheet processing apparatus 100 and the image forming apparatus 300 have an integrated structure. Also good.

  The sheet processing apparatus 100 includes a saddle stitching processing device (saddle unit) 135 and a flat binding processing device as a sheet stacking processing device. The sheet discharged from the image forming apparatus 300 is delivered to the entrance conveyance roller pair 102 of the sheet processing apparatus 100, and the delivery timing of the sheet is detected by the entrance sensor 101 at that time. The inlet conveyance roller pair 102 is driven by an inlet conveyance motor driver 278 (see FIG. 6 described later) and an inlet conveyance motor 208.

  The sheet conveyed by the inlet conveyance roller pair 102 passes through the conveyance path 103 and the punch unit 250 for punching the sheet, and then is delivered to the first shift conveyance roller pair 105 and the second shift conveyance roller pair 106. It is. The first and second shift transport roller pairs 105 and 106 are driven by a shift transport motor driver 290 (see FIG. 6 described later) and a shift transport motor 291 which will be described later.

  After driving the first and second shift conveyance roller pairs 105 and 106 by a predetermined fixed amount, the lateral registration detection sensor 104 detects the end position in the width direction orthogonal to the sheet conveyance direction. . From the obtained detection result, the lateral registration deviation amount of the sheet from the center position in the sheet conveying direction is obtained, and the sheet is oriented in the direction perpendicular to the paper surface of FIG. Direction / backward direction) (shift operation). This shift operation is performed while being conveyed by the pair of shift conveyance rollers 105 and 106. Since this shift operation (lateral registration correction) is a known technique, detailed description thereof is omitted.

  Thereafter, the sheet is conveyed by a predetermined amount, and the conveyance is stopped. The period during which the sheet is held stopped is the stable time. After the stable time has elapsed, the conveyance direction of the sheet is reversed and the conveyance is started, and the sheet is conveyed by a predetermined amount to correct the skew of the trailing edge of the sheet. The sheet is brought into contact with the trailing edge stopper member 251 and the skew of the trailing edge of the sheet is corrected. At this time, if necessary, the punch unit 250 can perform a punching process for forming punch holes in the rear end portion of the sheet.

  Thereafter, the sheet is conveyed by the conveyance roller 110, the separation roller 111, and the buffer roller pair 115, and then conveyed to either the upper conveyance path 117 or the bundle conveyance path 121 by controlling the posture of the flapper 118. When the sheet is guided to the upper conveyance path 117, the sheet is discharged to the upper tray 136 by the upper discharge roller 120. On the other hand, when the sheet is guided to the bundle conveyance path 121, the sheet sequentially passes through the lower conveyance path 126 by the buffer roller pair 122 and the bundle conveyance roller pair 124. FIG. 2 shows a state where the flapper 118 guides the sheet to the bundle conveyance path 121.

  When performing saddle stitch processing on the sheet, the posture of the flapper 125 is controlled, so that the sheet is transported to the saddle transport path 133 and further guided to the saddle stitch processing device 135 by the saddle entrance roller pair 134, and the saddle stitch processing device 135. In Saddle Stitching. The saddle stitching process is a general process and is not a main part of the present invention, and thus detailed description thereof is omitted.

  When the sheet is discharged to the lower tray 137, the sheet is conveyed to the lower conveyance path 126 by the bundle conveyance roller pair 124 and the flapper 125. Then, the sheet is discharged to the intermediate processing tray 138 by the lower discharge roller pair 128 and subjected to alignment processing on the intermediate processing tray 138 by a return means such as a paddle and a knurled belt (not shown). After that, the sheet bundle is bound by the stapler 132 as necessary, and then the sheet bundle is discharged to the lower tray 137 by the bundle discharge roller pair 130.

<Configuration of punch unit 250>
3, 4, and 5 are diagrams showing the configuration and operation of a punch unit 250 included in the sheet processing apparatus 100. Each of FIG. 3A to FIG. 5A is a perspective view of the punch unit 250, and each FIG. Each (C) is a cross-sectional view of the punch unit 250 as viewed from the direction of the arrow g in each (A).

  The first punch sensor 271 and the second punch sensor 272 determine where the slider 260 is located. For example, as shown in FIG. 3, when the first punch sensor 271 and the second punch sensor 272 are shielded from light by the slider 260, the slider 260 is positioned on the back side when viewed from the direction of the arrow g. On the other hand, as shown in FIG. 5, when the first punch sensor 271 and the second punch sensor 272 are not shielded from light, the slider 260 is positioned on the front side when viewed from the direction of the arrow g.

  The slider 260 is driven by a punch motor 221 driven by a punch motor driver 279 (see FIG. 6 described later), and moves in the directions of arrows P and Q shown in FIGS. For example, the slider 260 moves in the direction of the arrow Q when the punch motor 221 rotates clockwise as shown in FIG. 3, and moves in the direction of the arrow P when rotated counterclockwise as shown in FIG. When the pin 274 fixed to the punch 273 at the position of FIG. 3 moves the cam 275 in the direction perpendicular to the moving direction of the slider 260, the punch 273 interlocked with the pin 274 is moved to the sheet as shown in FIG. Perforate the sheet by moving perpendicular to the. Thereafter, when the slider 260 further moves, the state shown in FIG. 5 is obtained, and the punch 273 comes out of the sheet.

  The encoder 280 fixed to the opposite output shaft of the punch motor 221 causes the punch motor clock sensor 276 to generate a clock when the punch motor 221 rotates. By counting this clock, the amount of movement of the slider 260 operated by the punch motor 221 is detected. When the slider 260 moves once a predetermined distance, one punching operation is completed.

<Control block of image forming system>
FIG. 6 is a control block diagram of the image forming system. The system control unit 305 includes a CPU 310, a ROM 306 and a RAM 307 as storage means. The ROM 306 stores a control program, and the CPU 310 expands and executes the control program in the RAM 307, thereby executing overall control of the image forming system. That is, the system control unit 305 collectively controls the document feeding device control unit 301, the image reader control unit 302, the image signal control unit 303, the printer control unit 304, the operation unit 308, and the sheet processing device control unit 501. . The RAM 307 temporarily stores control data and is used as a work area for arithmetic processing associated with control.

  The document feeder controller 301 controls driving of the automatic document feeder 500 based on an instruction from the system controller 305. The image reader control unit 302 performs drive control on an optical system such as a light source, a lens, and an image sensor for reading a document surface, and transfers RGB analog image signals output from the image sensor to the image signal control unit 303. The image signal control unit 303 converts the RGB analog image signal received from the image reader control unit 302 into a digital signal in accordance with an instruction from the system control unit 305, performs various image processing, and sends it to the printer control unit 304. Output. The printer control unit 304 forms an image on a sheet.

  The operation unit 308 includes a plurality of keys for setting various functions relating to image formation, a display unit for displaying setting information, and the like. A key signal input by pressing each key of the operation unit 308 is supplied to the system control unit 305, and the system control unit 305 performs processing according to the key signal, and information regarding this processing is displayed on the display unit.

  The sheet processing apparatus control unit 501 is mounted on the sheet processing apparatus 100 and controls the operation of the sheet processing apparatus 100 by performing data communication with the system control unit 305 via a communication IC (not shown). The sheet processing apparatus control unit 501 includes a CPU 401, a ROM 402, and a RAM 403. The CPU 401 controls various drive units such as actuators and sensors that constitute the sheet processing apparatus 100 by developing and executing a control program stored in the ROM 402 in the RAM 403. For example, the sheet processing apparatus controller 501 includes the inlet sensor 101, the inlet conveyance motor 208 that drives the inlet conveyance roller pair 102, the shift conveyance motor 291 that drives the shift conveyance roller pair 105 and 106, and the like shown in FIG. Be controlled. The RAM 403 temporarily stores control data and is used as a work area for arithmetic processing associated with control.

<Reverse conveyance control of sheet in image forming system>
FIG. 7 is a flowchart of sheet reverse conveyance control executed in the image forming system. That is, conveyance of a sheet carried from the image forming apparatus 300 to the sheet processing apparatus 100, reversal of the conveyance direction by reversal conveyance control, skew correction and punching processing of the trailing edge of the sheet, and sheet conveyance of the punching process will be described. Here, a case of so-called copying (copying) of a document will be taken up. The control flow shown in FIG. 7 is realized in principle by the CPU 401 of the sheet processing apparatus control unit 501 controlling various drive units constituting the sheet processing apparatus 100 based on an instruction from the system control unit 305. The

  First, a document is set on the automatic document feeder 500, image forming conditions such as the number of copies, enlargement / reduction printing, presence / absence of punching processing are set, and a copy start instruction is input. Is read and an image of the read original surface is formed on the sheet. At this time, the CPU 401 receives sheet information related to a sheet on which an image is formed from the system control unit 305 (step S100).

  Here, a cassette for feeding sheets is designated by the user from among the cassettes 900a to 900d, or is automatically determined by the system control unit 305 in accordance with the set image forming conditions. The system control unit 305 transmits sheet information of the sheets stored in the designated or determined cassette to the sheet processing apparatus control unit 501. Here, it is assumed that the CPU 401 receives the sheet size stored in the selected cassette as sheet information.

  The CPU 401 determines the sheet size based on the received sheet information (step S101). Then, the CPU 401 sets a stable time for holding the sheet stopped in the reverse conveyance for reversing the sheet conveyance direction according to the determined sheet size (steps S102a, 102b, and 102c).

  FIG. 8 is an example of a table used by the CPU 401 to set a stable time, and is stored in the ROM 402. When the sheet size is a small size (the conveyance direction length is less than 216 mm), the stabilization time T is set to “5 (msec)” (step S102a). When the sheet size is a medium size (the conveyance direction length is 216 mm or more and less than 300 mm), the stabilization time T is set to “15 (msec)” (step S102b). When the sheet size is a large size (the length in the transport direction is 300 mm or more), the stabilization time T is set to “30 (msec)” (step S102c).

  The set value of the stabilization time T is not limited to the value shown in FIG. Further, the stabilization time of FIG. 8 is set when the sheet characteristics other than the sheet size, for example, the basis weight and material are the same, but only the sheet size is different. For a sheet having the same size and different other characteristics such as basis weight and material, a table corresponding to the table shown in FIG. It can be set as a structure. The CPU 401 reads an appropriate stabilization time as appropriate and sets the stabilization time.

  FIG. 9 is a timing chart showing the relationship between the sheet size and the stabilization time when the sheet is switched back. In FIG. 9, “forward direction” refers to conveying a sheet from the upstream side to the downstream side, and “reverse direction” refers to conveying the sheet from the downstream side to the upstream side opposite to the forward direction by reverse conveyance. Point to.

  Since the stabilization time when the sheet size is medium is shorter than the stabilization time when the sheet size is large, the processing can be performed faster by the difference time. Similarly, the stabilization time when the sheet size is small is shorter than the stabilization time when the sheet size is medium. Therefore, the processing can be performed faster by the difference time, and the sheet size is large. The processing speed can be further increased than the case.

  Subsequently, the CPU 401 controls the inlet conveyance motor driver 278, the shift conveyance motor driver 290, and the like to activate the motors such as the inlet conveyance motor 208 and the shift conveyance motor 291 (step S103). Thus, in order to receive the sheet on which the image is formed from the image forming apparatus 300, the entrance conveyance roller pair 102 and the shift conveyance roller pair 105 and 106 start to rotate in the direction in which the sheet is conveyed downstream.

  Subsequently, the CPU 401 determines whether or not passage of the sheet is detected by the entrance sensor 101 (step S104). If the sheet has not passed (“NO” in S104), the standby state is set in step S104. If the sheet passes (“YES” in S104), the process proceeds to step S105.

  FIG. 10 is a diagram illustrating a state in which the entrance sensor 101 detects that the leading edge of the sheet has entered the sheet processing apparatus 100. The CPU 401 conveys the sheet by a conveyance distance determined in advance according to the sheet size (step S105). This conveyance distance is the distance from the position where the inlet sensor 101, which is the sheet detection position, to the position where the reverse conveyance of the sheet is started. FIG. 11 is a diagram illustrating a state in which the sheet is stopped for the reverse conveyance. As the sheet size increases, the transport distance becomes longer.

  After step S105, the CPU 401 holds the sheet in a stopped state for the stabilization time set in any of steps S102a, 102b, and 102c (step S106). This is because immediately after stopping the conveyance of the sheet, it vibrates due to the inherent vibrations of the motors and the inertial force of the rollers and the sheet itself, and the load is increased, so it is necessary to wait for these vibrations to stabilize. is there. Here, the longer the sheet conveyance distance in step S105, that is, the longer the sheet conveyance direction length, the longer the stabilization time T is set. In other words, the stabilization time is set shorter as the sheet conveyance distance (the length in the sheet conveyance direction) becomes shorter. Therefore, the smaller the sheet size, the shorter the time interval between sheets to be conveyed, Productivity can be improved.

  After the stabilization time has elapsed in step S106, the CPU 401 reverses the sheet conveyance direction and conveys the sheet in the reverse direction (step S107). Further, the CPU 401 corrects the skew of the trailing edge of the sheet by conveying the sheet in the reverse direction by a certain distance, butting the trailing edge of the sheet against the trailing edge stopper member 251 and bending the sheet ( Step S108). FIG. 12 is a diagram illustrating a state in which the sheet conveyance direction is reversed and the trailing edge of the sheet is abutted against the trailing edge stopper member 251. In the state shown in FIG. 12, the CPU 401 controls the punch motor driver 279 to drive the punch motor 221 to execute punching processing on the sheet (step S109). Thereafter, the CPU 401 conveys the sheet in the forward direction and discharges the sheet to the upper tray 136 or the lower tray 137 (end).

<Other embodiments>
Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. Furthermore, each embodiment mentioned above shows only one embodiment of this invention, and it is also possible to combine each embodiment suitably.

  For example, in the above-described embodiment, a case where three types of sheet sizes are classified and three types of stable times are set has been described. However, the present invention is not limited to this, and the number of cases is smaller and the reverse is performed more finely. The stabilization time may be set from the linearity calculated from In the above embodiment, the sheet size is used as the sheet information. However, the present invention is not limited to this, but the basis weight, surface properties, thickness, gap, material (material type), presence / absence of coated / uncoated, stiffness, toner paste The stabilization time may be determined using one or more pieces of sheet information selected from the amount or the like. For example, the stabilization time is set longer as the basis weight is increased, the thickness is increased, the density of the material is increased, and the amount of toner is increased. Further, the sheet information is received from the upstream device holding the sheet information. However, the stable time obtained by the upstream device can be received instead of the sheet information.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program code. It is a process to be executed. In this case, the program and the storage medium storing the program constitute the present invention.

DESCRIPTION OF SYMBOLS 100 Sheet processing apparatus 251 Rear end stopper member 300 Image forming apparatus 305 System control part 301 Document feeding apparatus control part 302 Image reader control part 303 Image signal control part,
304 Printer Control Unit 308 Operation Unit 401 CPU
501 Sheet processing apparatus control unit

Claims (7)

Conveying means for conveying the sheet;
The sheet conveyed in the forward direction by the conveying means is stopped, the sheet is held for a predetermined stabilization time at the position where the sheet is stopped, and the conveyance direction of the sheet after the stabilization time has elapsed. Control means for controlling the conveying means so as to be reversed and conveyed in the reverse direction,
The control means sets the stabilization time to be longer as the load when the forward conveyance of the sheet is stopped and the reverse conveyance is increased based on the sheet information indicating the characteristics of the sheet. A sheet processing apparatus. A skew correction member against which the sheet abuts in order to correct skew of the trailing edge of the sheet conveyed by the conveying means;
The control means controls the conveying means to reverse the conveying direction of the sheet, convey the sheet in the reverse direction, and abut the sheet against the skew feeding correction member to thereby adjust the trailing edge of the sheet. The sheet processing apparatus according to claim 1, wherein skew feeding is corrected.   The sheet information is at least one selected from the size, basis weight, surface property, gap, material, presence / absence of coating / non-coating, rigidity, and toner paste amount of the sheet. Item 3. The sheet processing apparatus according to Item 1 or 2. The sheet information is the size of the sheet,
The sheet processing apparatus according to claim 3, wherein the control unit sets the stabilization time to be shorter as the length of the sheet in the conveyance direction becomes shorter. The sheet information is the thickness of the sheet,
The sheet processing apparatus according to claim 3, wherein the control unit sets the stabilization time to be shorter as the thickness of the sheet becomes thinner.   5. The control unit according to claim 2, wherein the control unit holds a table that defines a relationship between the sheet information and the stabilization time, and sets the stabilization time based on the sheet information from the table. The sheet processing apparatus according to claim 1. An image forming apparatus for forming an image on a sheet;
A sheet processing apparatus connected to the image forming apparatus and into which a sheet image-formed in the image forming apparatus is carried,
The image forming apparatus includes a transmission unit that transmits sheet information indicating the characteristics of the sheet to the sheet processing apparatus,
The sheet processing apparatus stops the sheet being conveyed in a forward direction with a conveying unit that conveys the sheet, and holds the sheet for a predetermined stabilization time at a position where the sheet is stopped. Control means for controlling the conveying means so as to reverse the conveying direction of the sheet after the stable time has elapsed and to convey the sheet in the reverse direction,
The control means sets the stabilization time to be longer as the load when the forward conveyance of the sheet is stopped and the reverse conveyance is increased based on the sheet information indicating the characteristics of the sheet. An image forming system.

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