JP2024070624A - SHEET PROCESSING APPARATUS AND CONTROL METHOD THEREOF - Google Patents

Abstract

[Problem] To facilitate jam removal by the user without providing an internal tray dedicated to jam removal. [Solution] A sheet processing device has a transport means for transporting multiple sheets, a bundle creating means for overlapping multiple sheets to create a sheet bundle, and a post-processing means for performing post-processing on the sheet bundle. When a jam occurs downstream of the bundle creating means, the sheet processing device controls the transport means and the bundle creating means to transport one or more sheets located upstream of the bundle creating means to the bundle creating means and to cause the bundle creating means to hold one or more sheets. [Selected Figure] Figure 1

Description

The present invention relates to a sheet processing device and a control method thereof.

A sheet processing device performs post-processing (e.g., sorting, binding, alignment) on sheets output from an image forming device or the like. When a sheet jam occurs in the sheet processing device, the sheet processing device immediately stops operation (sheet transport, post-processing), displays a message on the operation panel indicating that a jam has occurred, and prompts the user to remove the sheet. The user opens a door to access the sheet and removes the sheet. Typically, the longer the sheet transport path, the more sheets need to be removed and the more doors the user needs to access, making the user's work more complicated. According to Patent Document 1, it is proposed to place a dedicated internal tray in the sheet processing device to store stuck sheets resulting from a jam.

JP 2003-095508 A

Conventional technology makes it easy for users to remove jams, but requires a dedicated internal tray. This increases costs and requires the securing of installation space within the sheet processing device.

Therefore, the present invention aims to make it easier for users to clear jams.

The present invention relates to, for example,
a first conveying means for conveying a plurality of sheets entering from an entrance in order;
a bundle forming means for stacking the plurality of sheets conveyed by the conveying means to form a sheet bundle;
a second conveying means for conveying the sheet bundle from the bundle forming means;
a post-processing unit that performs post-processing on the sheet bundle conveyed by the second conveying unit;
a discharge means for discharging the sheet bundle that has been subjected to the post-processing by the post-processing means;
a control means for controlling the first conveying means, the bundle forming means, the second conveying means, the post-processing means, and the discharge means,
The control means
determining whether a jam has occurred on the upstream side or downstream side of the bundle forming means in a conveying direction of the sheet;
when the jam occurs downstream of the bundle forming means, the second conveying means, the post-processing means and the discharging means are stopped from operating, while the first conveying means continues to convey the sheets to the bundle forming means, causing the bundle forming means to form a sheet bundle for external discharge;
A sheet processing device is provided which, when a jam occurs upstream of the bundle creating means, stops operation of the first conveying means and the bundle creating means, while continuing the conveying of sheets to the bundle creating means by the second conveying means, the operation of the post-processing means, and the operation of the discharge means.

The present invention makes it easy for users to clear jams without having to provide an internal tray specifically for jam clearance.

FIG. 1 is a diagram illustrating an image forming system. FIG. FIG. FIG. 2 is a diagram for explaining functions of a CPU. FIG. 2 is a diagram illustrating a jam recovery unit. FIG. 5A to 5C are diagrams illustrating a method for creating a sheet bundle. 5A shows a method for controlling the inlet rollers, and FIG. 5B shows a method for controlling the pair of conveying rollers 22. 5A and 5B are diagrams showing a method of controlling a pair of conveying rollers 24. 5A to 5C are diagrams showing a method of controlling a pair of conveying rollers 26. FIG. 6A and 6B are diagrams for explaining a method of discharging a sheet stack caused by a jam. 11 is a flowchart illustrating a jam processing procedure. FIG. 4 is a diagram illustrating a driving timing of the roller. FIG. 11 is a diagram for explaining a third embodiment. 11 is a flowchart illustrating a process for determining a discharge method.

The following embodiments are described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe multiple features, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicate explanations are omitted.

Example 1
[Outline of Image Forming System]
1 is a schematic cross-section of an image forming system 100 having an image forming apparatus 1 and a post-processing apparatus 4. The image forming apparatus 1 forms an image on a sheet P. The image forming apparatus 1 may use any of an electrophotographic method, an inkjet method, a thermal transfer method, etc., but here, an electrophotographic method is used as an example. The post-processing apparatus 4 performs post-processing (e.g., alignment, punching, stapling, bookbinding) on the sheet P. Note that a conveying device that relays the sheet P from the image forming apparatus 1 to the post-processing apparatus 4 may be connected between the image forming apparatus 1 and the post-processing apparatus 4.

The image forming apparatus 1 has a plurality of feeding devices 6 that accommodate a plurality of sheets P. The feeding devices 6 feed the sheets one by one at a predetermined feeding interval. The sheet P fed from the feeding device 6 is corrected for skew by the registration rollers 7, and is transported to the transfer nip by the registration rollers 7. The transfer nip is composed of a photosensitive drum 9 rotatably supported by the image forming cartridge 8, and a transfer roller 10 to which a predetermined transfer voltage is applied. A toner image is formed on the surface of the photosensitive drum 9 through the processes of exposure, charging, latent image formation, and development in the image forming cartridge 8. In particular, the laser scanner unit 15 forms an electrostatic latent image by exposing the uniformly charged surface of the photosensitive drum 9 to laser light. The transfer nip transfers the toner image from the photosensitive drum 9 to the sheet P. The sheet P is transported to the fixing device 11, which applies heat and pressure to the sheet P and the toner image to fix the toner image on the sheet P. The horizontal conveying section 14 conveys the sheet P that has passed through the fixing unit 11, and discharges it to the post-processing device 4. When double-sided printing is performed, the sheet P is conveyed to the inversion rollers 12, which execute a switchback conveyance in which the leading and trailing ends of the sheet P are switched. As a result, the sheet P is sent to the re-feeding section 13. The re-feeding section 13 conveys the sheet P again to the registration rollers 7. An image is then formed again on the sheet P.

The post-processing device 4 has a housing 4a. Inside the housing 4a, a buffer section 81 and a post-processing section 71 are provided. The buffer section 81 has a bundle creation section 60 that overlaps a plurality of sheets P to form a sheet bundle and temporarily holds the sheet bundle. The buffer section 81 may temporarily hold only one sheet P. The post-processing section 71 accumulates a predetermined number of sheets P and performs alignment processing and binding processing. The post-processing device 4 has a conveying path R1 and a conveying path R2. The conveying path R1 is a conveying path from the entrance roller 21 to the pair of conveying rollers 24. Alternatively, the conveying path R1 may be understood as a conveying path from the entrance roller 21 to the bundle creation section 60. The conveying path R2 is a conveying path that connects the backflow prevention valve 23 (or the bundle creation section 60) and the post-processing section 71. In this way, the conveying path R1 and the conveying path R2 are connected to the bundle creation section 60. In the following, the front end of the sheet P in the conveying direction is referred to as the leading end, and the rear end of the sheet P in the conveying direction is referred to as the trailing end. Of the two ends of the sheet P, the end that enters the post-processing device 4 first is called the first end, and the end that enters the post-processing device 4 later is called the second end. Note that the leading end may be changed from the first end to the second end, and the trailing end may be changed from the second end to the first end, due to switchback transport.

The entrance roller 21 is a transport roller that receives and transports the sheet P that has entered through the entrance from the horizontal transport section 14 to the post-processing device 4. There may be a difference between the transport speed of the sheet P in the post-processing device 4 and the transport speed of the sheet P in the horizontal transport section 14. In order to absorb this speed difference, a one-way clutch may be provided in the drive mechanism of the transport roller pair 53 of the horizontal transport section 14. When the sheet P is pulled by the entrance roller 21, the transport roller pair 53 of the horizontal transport section 14 rotates freely, absorbing the speed difference. A sheet sensor 52 that detects the passage of the sheet P is arranged in the horizontal transport section 14.

The post-processing device 4 has an upper tray 25 and a lower tray 37. When the sheet P is discharged to the upper tray 25, the sheet P is transferred from the conveying roller pair 22 to the conveying roller pair 24 and discharged to the upper tray 25 through the discharge port 54. The sheet sensor 51 detects whether a sheet or a sheet stack is present on the upper tray 25. The conveying roller pair 22 is a conveying roller pair provided downstream of the entrance roller 21 in the conveying direction of the sheet P. The conveying roller pair 24 is a conveying roller pair provided downstream of the conveying roller pair 22 in the conveying direction of the sheet P. The conveying roller pair 24 can be freely rotated forward and backward, so it may also be called a reversing roller pair.

When the sheet P is discharged to the lower tray 37, the conveyance of the sheet P is temporarily stopped when the rear end (second end) of the sheet P passes through the check valve 23. After that, the conveyance roller pair 24 switches the sheet P back, and the second end of the sheet P is replaced from the rear end to the front end. The front end (second end) of the sheet P is guided to the conveyance path R2 by the check valve 23, and is conveyed further downstream by the conveyance roller pair 26. When the front end (second end) of the sheet P reaches the conveyance roller pair 26, the conveyance roller pair 24 changes from a clamping state (contact state) to an open state (contact release state). In other words, the two rollers constituting the conveyance roller pair 24 are separated. This makes it possible for the conveyance roller pair 24 to accept the succeeding sheet P. The conveyance roller pair 26 is temporarily stopped while the conveyance roller pair 26 is clamping the sheet P. When the succeeding sheet P passes through a predetermined position, the conveyance roller pair 26 starts to rotate in the reverse direction. This conveys the sheet P toward the conveyance roller pair 24. As a result, the succeeding sheet P is stacked on top of the preceding sheet P to form a sheet bundle. The pair of conveying rollers 26 repeatedly switches back the sheet P or the sheet bundle, making it possible to buffer multiple sheets P regardless of the length of the sheets P. This operation is called a buffer operation or a stacking operation. The mechanisms involved in the buffer operation are called the bundle creation unit 60 and the buffer unit 81. The buffer operation allows image formation on the sheets P in the image forming apparatus 1 to continue even while post-processing is being performed in the post-processing unit 71. In other words, by having the succeeding sheet P wait in the buffer unit 81 until post-processing of the preceding sheet P is completed, the overall productivity of the image forming system 100 is maintained.

The sheet P conveyed from the conveying roller pair 26 is sent to the conveying roller pair 29 via the conveying roller pair 28, and is conveyed to the post-processing section 71. The post-processing section 71 has an upper guide 31 and a lower guide 32, and the sheet P is guided by the upper guide 31 and the lower guide 32.

A sheet sensor 38 is disposed in the transport section connecting the transport roller pair 28 and the transport roller pair 29. The sheet sensor 38 is a reflective photosensor that determines the presence or absence of a sheet P. An alignment reference plate 39 is disposed at the most downstream portion of the post-processing section 71. When the leading edge (second end) of the sheet P hits the alignment reference plate 39, the sheet stack is aligned (matched) in the vertical direction.

A flexible pressing guide 56 is fixed to the upper guide 31. The pressing guide 56 abuts against the sheet P in the post-processing section 71 with a predetermined pressure. The half-moon roller 33 is a paddle member for pushing the sheet P that has passed through the pair of conveying rollers 29 into the alignment reference plate 39. The half-moon roller 33 is rotatably supported by the upper guide 31 downstream of the pressing guide 56. After the rear end (first end) of the sheet P passes the sheet sensor 38, the half-moon roller 33 conveys the sheet P toward the alignment reference plate 39. The contact force of the half-moon roller 33 against the sheet P is adjusted to a force that causes the half-moon roller 33 to slip on the sheet P when the sheet P abuts against the alignment reference plate 39. In addition, a stack pressing flag 30 is rotatably supported downstream of the pair of conveying rollers 29. The stack holding flag 30 prevents the rear end of the sheet P from lifting up so that the rear end (first end) of the sheet P stacked in the post-processing section 71 does not interfere with the leading end (second end) of the following sheet P.

When the post-processing section 71 has finished aligning a predetermined number of sheets P (sheet stack), the stapler 50 performs the binding operation. When the binding operation is completed, the guide drive section 35 moves the discharge guide 34 from the standby position toward the discharge rollers 36. This causes the discharge guide 34 to push the sheet stack toward the discharge rollers 36. The discharge guide 34 again switches the leading and trailing ends of the sheet stack. When the leading end (first end) of the sheet stack reaches the discharge rollers 36, the discharge guide 34 stops and returns to the standby position. The discharge rollers 36 discharge the sheet stack handed over from the discharge guide 34 to the lower tray 37.

The display device 5 displays the operating status of the image forming system 100, such as jams and malfunctions. The display device 5 instructs the user to replace consumables and remove jammed sheets P. The display device 5 may have a touch sensor that detects user input.

[Buffer section]
FIG. 2 is an enlarged view of the cross section of the buffer unit 81. The first upper guide 40, the first lower guide 41, and the second lower guide 43 form a transport path R1. Between the entrance roller 21 and the transport roller pair 22, the sheet P is guided by a transport guide constituted by the first upper guide 40 and the first lower guide 41. The first upper guide 40 is provided with a sheet sensor 27. The sheet sensor 27 may be called an entrance sensor because it is provided near the entrance of the transport path R1. The sheet sensor 27 is a reflective photosensor that determines the presence or absence of the sheet P. The first lower guide 41 facing the sheet sensor 27 is provided with a hole. This is to prevent infrared light from the sheet sensor 27 from being reflected by the first lower guide 41 and returning. In other words, the infrared light from the sheet sensor 27 returns to the sheet sensor 27 only during the period when the sheet P is passing through. The size of the hole is larger than the spot diameter of the infrared light.

The third upper guide 46 and the third lower guide 47 form the transport path R2. It may be understood that the second upper guide 42 and the second lower guide 43 also form part of the transport path R2. A check valve 23 is provided downstream of the transport roller pair 22. The check valve 23 has a rotating shaft 23a and is provided so as to be rotatable about the rotating shaft 23a. The rotating shaft 23a is constantly biased in the C2 direction by a spring (not shown). The tip of the check valve 23 and the tip of the second upper guide 42 are formed in a comb shape. When the sheet P is fed by the transport roller pair 22, the check valve 23 is pressed by the sheet P and rotates in the C1 direction, allowing the sheet P to pass. When the rear end of the sheet P passes through the check valve 23, the check valve 23 rotates in the C2 direction and returns to its original position.

The conveying roller pair 24 is a roller pair consisting of an upper roller 24a and a lower roller 24b. A driving force (rotational force) is transmitted to the upper roller 24a and the lower roller 24b, and they rotate synchronously. A separation lever 44 is connected to the upper roller 24a. The separation lever 44 has a lever fulcrum shaft 44a and a solenoid connection shaft 44b. The separation lever 44 is supported so as to be rotatable around the lever fulcrum shaft 44a. The separation lever 44 is rotatably connected to a solenoid 45 at the solenoid connection shaft 44b. When a current flows through the solenoid 45, the core of the solenoid 45 moves in the direction D1. As a result, the separation lever 44 rotates in the direction E1, and the conveying roller pair 24 is in a separated state. When the current flowing through the solenoid 45 stops, the upper roller 24a moves in the direction E2 due to the spring 48, and the solenoid 45 moves in the direction D2.

The conveying roller pair 24 and the conveying roller pair 26 are capable of switching the rotation direction. The conveying roller pair 24 and the conveying roller pair 26 can convey the sheet P in either the F1 direction or the F2 direction when performing the buffer operation.

[Hardware configuration]
FIG. 3 shows the controller of the image forming system 100. Here, the hardware configuration of the post-processing device 4 will be mainly described in detail. The video controller 301 controls the image forming device 1 and the post-processing device 4 in an integrated manner. The engine control unit 302 controls the image forming device 1. The main control unit 303 controls the post-processing device 4. The signal line 304 is a signal line that transmits an instruction (command) from the video controller 301 to the engine control unit 302 by serial communication. The signal line 305 is a signal line that transmits a command from the video controller 301 to the main control unit 303 by serial communication. The signal line 306 is a signal line that transmits a status from the engine control unit 302 to the video controller 301 in response to the command. The signal line 307 is a signal line that transmits status data from the main control unit 303 to the video controller 301 by serial communication. When performing image formation, the video controller 301 transmits serial commands to the engine control unit 302 and the main control unit 303, and receives status data from the engine control unit 302 and the main control unit 303. In this way, when a plurality of devices are connected and operated, the video controller 301 manages the control and state of each device, and maintains the consistency of the operation between the devices. The engine control unit 302 controls the actuator and the electrophotographic process provided in the image forming apparatus 1. The engine control unit 302 controls the motor 350 and causes the motor 350 to drive the conveying roller pair 53. The engine control unit 302 obtains the detection result of the sheet sensor 52, and transmits the detection result to the main control unit 303 via the video controller 301. The motor 350 may be connected to the I/O port 313 of the main control unit 303 via a drive circuit (not shown). The sheet sensor 52 may also be directly connected to the I/O port 313 of the main control unit 303.

The main control unit 303 is an integrated circuit (IC) that executes various controls by the CPU 308 executing a control program stored in the ROM 310. The RAM 309 is a memory that temporarily stores control data required for the operation of the post-processing device 4. The ROM 310 is a memory that stores the control program and control tables required for the operation of the post-processing device 4. The communication circuit 311 is a communication circuit that allows the main control unit 303 to communicate with the video controller 301. The system timer 312 is a timer circuit that manages the timing required for various controls. The I/O port 313 is a circuit that outputs control signals to various units in the post-processing device 4 and inputs signals from the various units. The bus 314 connects the various units so that they can communicate with each other.

The input circuit 315 transmits the input signal from the sheet sensor 27 to the main control unit 303. The input circuit 329 transmits the input signal from the sheet sensor 38 to the main control unit 303.

The drive circuit 318 receives control signals from the main control unit 303 and drives the motors 341 to 345. The drive circuit 323 drives the solenoid 45. The motor 341 drives the inlet roller 21. The motor 342 drives the transport roller pair 22. The motor 343 drives the transport roller pair 24. The motor 344 drives the transport roller pair 26. The motor 345 drives the transport roller pair 28 and the transport roller pair 29. The solenoid 45 drives the separation lever 44.

The drive circuit 322 receives control signals from the main control unit 303 and drives the motors 346 to 349. The motor 344 drives the discharge roller 36. The motor 347 drives the discharge guide 34. The motor 348 drives the half-moon roller 33. The motor 349 drives the stapler 50.

[Function block]
4 shows a number of functions that the CPU 308 realizes according to a control program. However, some or all of the functions may be realized by a hardware circuit such as an ASIC (application specific integrated circuit) or an FPGA (field programmable gate array). Only the parts related to this embodiment will be described here.

The sensor control unit 420 inputs detection signals from the sheet sensor 27 and the sheet sensor 38 to the transport control unit 401. The transport control unit 401 is responsible for control related to the transport of the sheet P. The horizontal transport control unit 411 controls the horizontal transport unit 14 via the video controller 301 and the engine control unit 302. The buffer control unit 412 controls the buffer operation of the buffer unit 81. For example, based on the input from the sensor control unit 420, the buffer control unit 412 controls the operation of the buffer unit 81 and the transport to the upper tray 25 or the lower tray 37 via the motor control unit 421 or the solenoid control unit 422. The buffer control unit 412 also manages the position of the sheet P based on the input from the sensor control unit 420.

The post-processing control unit 413 acquires the detection result of the sheet sensor 38 via the sensor control unit 420. The post-processing control unit 413 controls the operation timing of the motors 346 to 349 via the motor control unit 421 according to the detection result.

The timer group 414 has multiple timers required to control the operation timing and operation content of the inlet roller 21 and the conveying roller pairs 22, 24, and 26. The timer group 414 may be implemented as a hardware circuit within the system timer 312.

The jam processing section 415 detects a jam of the sheet P based on the detection results of the sheet sensors 27, 38, and 50, and performs jam processing of the sheet P or displays a message on the display device 5.

Figure 5 shows details of the jam processing unit 415. The jam detection unit 511 detects whether a jam of sheet P has occurred near the sheet sensor 27 (buffer unit 81) based on the detection result of the sheet sensor 27. The jam detection unit 511 detects whether a jam of sheet P has occurred near the sheet sensor 38 (e.g., post-processing unit 71) based on the detection result of the sheet sensor 38. The jam detection unit 511 detects whether a jam of sheet P has occurred near the sheet sensor 52 (horizontal conveying unit 14) based on the detection result of the sheet sensor 52.

For example, the jam detection unit 511 monitors the time (passing time) from when the leading edge of the sheet P is detected to when the trailing edge of the sheet P is detected using the system timer 312 or an internal timer. For example, when the leading edge of the sheet P is detected, the jam detection unit 511 starts an internal timer. If the trailing edge of the sheet P is detected before the internal timer finishes timing a predetermined time, the jam detection unit 511 determines that a jam has not occurred. On the other hand, if the trailing edge of the sheet P is not detected before the internal timer finishes timing a predetermined time, the jam detection unit 511 determines that a jam has occurred.

The jam position determination unit 512 identifies the location of the jam based on whether the sensor that detected the jam is the sheet sensor 27, 38, or 50. For example, if the sheet sensor 27 detects a jam, the jam position determination unit 512 may determine that the jam has occurred upstream of the buffer unit 81 or the bundle creation unit 60. If the sheet sensor 52 detects a jam, the jam position determination unit 512 may determine that the jam has occurred in the horizontal conveyance unit 14 (upstream of the buffer unit 81). If the sheet sensor 38 detects a jam, the jam position determination unit 512 may determine that the jam has occurred in the post-processing unit 71 (downstream of the buffer unit 81).

The preceding sheet determination unit 513 determines whether a sheet P or a sheet stack is present in the upper tray 25 based on the detection result of the sheet sensor 51. The message creation unit 514 creates a message that is useful to a user who is clearing the jam, and displays it on the display device 5. The message may include information such as the occurrence of a jam and the position of a door that should be opened to remove the sheet. In addition to text information, the message may also include an image showing the position of the door.

The offset amount determination unit 515 determines the offset amount k between the leading edge of the preceding sheet P and the leading edge of the following sheet included in the sheet bundle formed by the bundle creation unit 60. Normally, the offset amount k is set to a predetermined value kt to assist the sheet bundle alignment operation in the post-processing unit 71. If a jam occurs, the offset amount k may be temporarily reduced. This point will be described in detail in Example 2.

The discharge method determination unit 516 determines the discharge method of the sheet bundle formed by the bundle creation unit 60 when a jam occurs. The discharge methods include a method of discharging the sheet bundle to the upper tray 25, and a method of stopping the discharge of the sheet bundle while protruding (exposing) a part of the sheet bundle from the discharge port 54 and leaving the remaining part of the sheet bundle in the buffer unit 81. This point will be described in detail in Example 3.

[Buffer operation]
Next, an overview of the operation of the buffer control unit 412 to overlap a plurality of sheets P will be described with reference to FIG. 7A to FIG. 7G. Here, the first sheet P to be transported is denoted as P1. The second sheet P to be transported is denoted as P2. The third sheet P to be transported is denoted as P3. The sheet bundle formed by overlapping the sheets P1 and P2 is denoted as W. The transport speeds of the transport roller pairs 22, 24, and 26 are denoted as V1 and V2 (V1<V2). The transport speed V1 is the transport speed before acceleration, and the transport speed V2 is the transport speed after acceleration. Here, acceleration (speed increase) is an acceleration process for ensuring a sheet interval (hereinafter referred to as a paper interval) required when overlapping the sheets P in the buffer unit 81 and when sending the sheet bundle downstream. The sheet interval generally refers to the distance or transport time from the rear end of the preceding sheet Pi to the front end of the following sheet Pi+1 (i is an arbitrary integer).

Figure 7 (A) shows that the conveying speed of the conveying roller pair 22 and the conveying roller pair 24 is accelerated to V2 at the timing t0 when the rear end (second end) of the sheet P1 passes the sheet sensor 27.

Figure 7 (B) shows that the sheet P1 is temporarily stopped when the rear end of the sheet P1 moves a predetermined distance from the sheet sensor 27 and passes through the check valve 23. The conveying speed of the conveying roller pair 22 returns to V1 to receive the sheet P2.

Figure 7 (C) shows that the rotation direction of the transport roller pair 24 switches from forward to reverse, and sheet P1 is transported in the F1 direction at transport speed V2. Sheet P2 is transported to the transport roller pair 22 at transport speed V1.

Figure 7 (D) shows that the leading edge (second edge) of sheet P1 stops at a position transported a predetermined amount Lstop from the transport roller pair 26. In addition, at the timing when sheet P1 is clamped by the transport roller pair 26, the separation lever 44 moves the upper roller 24a in the E1 direction, separating the upper roller 24a from the lower roller 24b. After the upper roller 24a separates from the lower roller 24b, the leading edge (first edge) of sheet P2 passes through the transport roller pair 24.

Figure 7 (E) shows that the conveying speed of the conveying roller pair 22 and the conveying roller pair 24 is accelerated to V2 after the rear end (second end) of the sheet P2 passes the sheet sensor 27. The timing when a predetermined time Twait has elapsed from the timing t0 when the rear end (second end) of the sheet P2 passes the sheet sensor 27 may be called t1. At the timing t1, the conveying roller pair 26 starts to rotate in the reverse direction. As a result, the sheet P1 sandwiched between the conveying roller pair 26 is conveyed in the F2 direction. When the conveying speeds of the sheets P1 and P2 become equal, the upper roller 24a moves in the E2 direction and cooperates with the lower roller 24b to sandwich the sheets P1 and P2. The conveying speed (circumferential speed) of the conveying roller pair 24 is adjusted to V2, which is the conveying speed of the sheets P1 and P2, before the sheets P1 and P2 are sandwiched.

Figure 7(F) shows that sheets P1 and P2 form sheet stack W after the rear end (second end) of sheet P2 passes through check valve 23. However, the second end of sheet P1 and the second end of sheet P2 are offset by a distance k. This distance k is the offset amount. As in Figures 7(B) and 7(C), in Figure 7(F) as well, sheet stack W is temporarily stopped when the rear end of sheet stack W passes through check valve 23. Then, the rotation direction of conveying roller pair 24 switches from forward to reverse.

Figure 7 (G) shows that the sheet stack W is transported in the direction F1 at a transport speed V2 toward the post-processing section 71. When the sheet stack W is sandwiched between the transport roller pair 26, the separation lever 44 separates the upper roller 24a from the lower roller 24b. In other words, the upper roller 24a moves in the direction E1. This enables the transport roller pair 24 to accept the sheet P3.

Figure 7 (H) shows that after the sheet stack W is sent to the post-processing section 71, sheet P3 is newly buffered. In this case, after the rear end of the sheet stack W passes through the pair of transport rollers 24, the upper roller 24a stops once. Sheet P3 enters the pair of transport rollers 24 with the pair of transport rollers 24 separated. When the rear end of sheet P3 passes through the sheet sensor 27, the transport speed of the pair of transport rollers 22 is increased from V1 to V2. After that, the upper roller 24a moves in the direction of E2, and the pair of transport rollers 24 comes into contact. The rotation direction of the upper roller 24a switches from reverse to forward rotation, and the sheet P3 is transported in the direction of F2 at the transport speed V2. Before the rear end of sheet P3 passes through the pair of transport rollers 22, the pair of transport rollers 24 starts transporting sheet P3.

By repeating the series of operations shown in Figures 7(A) to 7(H) in this manner, a sheet stack W is formed and sent to the post-processing section 71.

Here, two sheets P1 and P2 are buffered, but this is only one example. If the third sheet P3 is also buffered, after the operation shown in FIG. 7(G), the leading edge of the sheet stack W stops at a position (pause position) transported a predetermined amount Lstop from the transport roller pair 26. Then, an overlapping operation is applied to the sheet stack W and sheet P3. The overlapping operation is the same as the overlapping operation of sheets P1 and P2 described in relation to FIG. 7(D) to FIG. 7(G).

[Control of each roller during buffer operation]
(1) Method for Controlling the Inlet Rollers 21 FIG. 8A shows a method for controlling the inlet rollers 21 executed by the CPU 308 (buffer control unit 412).

In S801, the buffer control unit 412 sets the conveying speed of the inlet roller 21 to the target speed V1 in the drive circuit 318, starts the motor 341, and starts rotating the inlet roller 21.

In S802, the buffer control unit 412 determines whether the rear end of the sheet P has been detected based on the detection result of the sheet sensor 27. If the rear end of the sheet P is detected, the buffer control unit 412 advances the process to S803.

In S803, the buffer control unit 412 determines whether the sheet P that has passed the sheet sensor 27 is the final sheet based on the job information received from the video controller 301. If sheet P is not the final sheet, the buffer control unit 412 advances the process to S802. On the other hand, if sheet P is the final sheet, the buffer control unit 412 advances the process to S804.

In S804, the buffer control unit 412 sends a stop command to the drive circuit 318 to stop the motor 341, and stops the rotation of the inlet roller 21.

(2) Method for Controlling the Pair of Conveying Rollers 22 (Pre-buffer Rollers) FIG. 8B shows a method for controlling the pair of conveying rollers 22 executed by the CPU 308 (buffer control unit 412).

In S811, the buffer control unit 412 starts the rotation of the conveying roller pair 22. For example, the buffer control unit 412 starts the motor 342 that drives the conveying roller pair 22 by outputting a command to the drive circuit 318 to instruct the motor 342 to start. Note that the initial conveying speed is set to the target speed V1.

In S812, the buffer control unit 412 determines whether the rear end of the sheet P has been detected based on the detection result of the sheet sensor 27. If the rear end of the sheet P is detected, the buffer control unit 412 advances the process to S813.

In S813, the buffer control unit 412 outputs an acceleration command to the drive circuit 318 to start accelerating the pair of conveying rollers 22. This sets the conveying speed to the target speed V2.

In S814, the buffer control unit 412 turns on the deceleration timer 611. A predetermined time is set in the deceleration timer 611. The predetermined time is equal to the transport time required from the timing when the rear end of the sheet P passes the sheet sensor 27 to the timing when the rear end of the sheet P passes the pair of transport rollers 22. In this way, by monitoring the deceleration timer 611, the buffer control unit 412 can know the timing when the rear end of the sheet P leaves the pair of transport rollers 22.

In S815, the buffer control unit 412 determines whether the deceleration timer 611 has timed out. This determination corresponds to determining whether the trailing edge of the sheet P has passed through the pair of conveying rollers 22. When the deceleration timer 611 has timed out, the buffer control unit 412 advances the process to S816.

In S816, the buffer control unit 412 outputs a deceleration command to the drive circuit 318 to start decelerating the pair of conveying rollers 22. This sets the conveying speed to the target speed V1.

In S817, the buffer control unit 412 determines whether the sheet P that has passed through the pair of conveying rollers 22 is the final sheet based on the job information received from the video controller 301. If the sheet P is not the final sheet, the buffer control unit 412 advances the process to S812. On the other hand, if the sheet P is the final sheet, the buffer control unit 412 advances the process to S818.

At S818, the buffer control unit 412 sends a stop command to the drive circuit 318 to stop the motor 342, and stops the rotation of the conveying roller pair 22.

(3) Method for Controlling the Pair of Conveying Rollers 24 (Reversing Rollers) FIG. 9 shows a method for controlling the pair of conveying rollers 24 executed by the CPU 308 (buffer control unit 412).

In S901, the buffer control unit 412 determines whether the sheet P that has passed through the pair of conveying rollers 22 is the first sheet based on the job information received from the video controller 301. If the sheet P is the first sheet, the buffer control unit 412 advances the process to S902. On the other hand, if the sheet P is not the first sheet, the buffer control unit 412 advances the process to S921.

In S902, the buffer control unit 412 starts the forward rotation of the conveying roller pair 24. The buffer control unit 412 sends a command to the drive circuit 318 to set the conveying speed of the conveying roller pair 24 to the target speed V1 and set the rotation direction to forward. The drive circuit 318 starts the motor 343 in accordance with the command and starts the forward rotation of the conveying roller pair 24. The buffer control unit 412 also sends a command to the drive circuit 318 to start the contact of the conveying roller pair 24. The drive circuit 318 controls the solenoid 45 in accordance with the command and causes the solenoid 45 to execute the contact of the conveying roller pair 24.

In S903, the buffer control unit 412 determines whether the rear end of the sheet P has been detected based on the detection result of the sheet sensor 27. If the rear end of the sheet P is detected, the buffer control unit 412 advances the process to S904.

In S904, the buffer control unit 412 outputs an acceleration command to the drive circuit 318 to start accelerating the pair of conveying rollers 24. This sets the conveying speed to the target speed V2.

In S905, the buffer control unit 412 turns on the inversion timer 621, the separation timer 622, and the stop timer 623. A predetermined time is set in the inversion timer 621. The predetermined time is equal to the transport time required from the timing when the rear end of the sheet P passes the sheet sensor 27 to the timing when the rear end of the sheet P passes the backflow prevention valve 23. In this way, the buffer control unit 412 can know the timing when the rear end of the sheet P passes the backflow prevention valve 23 by monitoring the inversion timer 621. The timing when the sheet P passes the backflow prevention valve 23 is the timing when the reverse rotation of the conveying roller pair 24 starts. A predetermined time is set in the separation timer 622. The predetermined time is the transport time from the timing when the rear end (second end) of the sheet P passes the sheet sensor 27 to the timing when the front end (second end) of the sheet P passes the conveying roller pair 26. A predetermined time is set in the stop timer 623. The predetermined time is the transport time from the timing when the rear end (second end) of the sheet P passes the sheet sensor 27 to the timing when the reverse rotation of the conveying roller pair 24 is completed.

In S906, the buffer control unit 412 determines whether the inversion timer 621 has timed out. If the inversion timer 621 has timed out, the buffer control unit 412 advances the process to S907.

In S907, the buffer control unit 412 starts the reverse rotation of the conveying roller pair 24. The buffer control unit 412 sends a command to the drive circuit 318 to stop the rotation of the conveying roller pair 24, set the rotation direction to reverse, and restart the motor 343.

In S908, the buffer control unit 412 determines whether the separation timer 622 has timed out. If the separation timer 622 has timed out, the buffer control unit 412 advances the process to S909.

In S909, the buffer control unit 412 starts separating the pair of conveying rollers 24. The buffer control unit 412 sends a command to the drive circuit 318 to start separating the pair of conveying rollers 24. The drive circuit 318 controls the solenoid 45 in accordance with the command, causing the solenoid 45 to separate the pair of conveying rollers 24.

In S910, the buffer control unit 412 determines whether the stop timer 623 has timed out. If the stop timer 623 has timed out, the buffer control unit 412 advances the process to S911.

In S911, the buffer control unit 412 stops the rotation of the conveying roller pair 24. The buffer control unit 412 stops the rotation of the conveying roller pair 24 by sending a command to the drive circuit 318.

In S912, the buffer control unit 412 determines whether the sheet P that has passed through the pair of conveying rollers 24 is the final sheet based on the job information received from the video controller 301. If the sheet P is not the final sheet, the buffer control unit 412 advances the process to S921. On the other hand, if the sheet P is the final sheet, the buffer control unit 412 ends control of the pair of conveying rollers 24.

In S921, the buffer control unit 412 determines whether the rear end of the sheet P has been detected based on the detection result of the sheet sensor 27. If the rear end of the sheet P is detected, the buffer control unit 412 advances the process to S922.

In S922, the buffer control unit 412 turns on the start timer 624, the nip timer 625, the reversal timer 621, and the separation timer 622. The start timer 624 is set to a predetermined time. The predetermined time is equal to the transport time from when the rear end of the sheet P passes the sheet sensor 27 to when the transport roller pair 26 starts. The predetermined time set in the nip timer 625 is equal to the time from when the rear end of the sheet P passes the sheet sensor 27 to when the transport speed of the transport roller pair 24 reaches the target speed V2.

In S923, the buffer control unit 412 determines whether the start-up timer 624 has timed out. If the start-up timer 624 has timed out, the buffer control unit 412 advances the process to S924.

At S924, the buffer control unit 412 starts the forward rotation of the pair of transport rollers 24. The buffer control unit 412 sends a command to the drive circuit 318 to set the transport speed of the pair of transport rollers 24 to the target speed V1 and set the rotation direction to forward rotation. The drive circuit 318 starts the motor 343 in accordance with the command, and starts the forward rotation of the pair of transport rollers 24.

In S925, the buffer control unit 412 determines whether the nip timer 625 has timed out. If the nip timer 625 has timed out, the buffer control unit 412 advances the process to S926.

In S926, the buffer control unit 412 sends a command to the drive circuit 318 to start contacting the pair of conveying rollers 24. The drive circuit 318 controls the solenoid 45 in accordance with the command, causing the solenoid 45 to execute contacting of the pair of conveying rollers 24. The buffer control unit 412 then advances the process to S906. The process from S906 onwards is as already described.

(4) Method for Controlling the Pair of Conveying Rollers 26 FIG. 10 shows a method for controlling the pair of conveying rollers 26 executed by the CPU 308 (buffer control unit 412).

In S1001, the buffer control unit 412 determines whether the trailing end of the sheet P has been detected based on the detection result of the sheet sensor 27. If the trailing end of the sheet P is detected, the buffer control unit 412 advances the process to S1002.

In S1002, the buffer control unit 412 determines whether the sheet P that has passed the sheet sensor 27 is the first sheet based on the job information received from the video controller 301. If the sheet P is the first sheet, the buffer control unit 412 advances the process to S1003. On the other hand, if the sheet P is not the first sheet, the buffer control unit 412 advances the process to S1010.

In S1003, the buffer control unit 412 turns on the start timer 631 and the stop timer 633. The specified time set in the start timer 631 is the time from when the sheet sensor 27 detects the rear end of the sheet P to when the pair of conveying rollers 24 starts to rotate in the reverse direction. The specified time set in the stop timer 633 is the time from when the sheet sensor 27 detects the rear end of the sheet P to when the leading edge (second edge) of the sheet P reaches a position a specified distance Lstop away from the pair of conveying rollers 26.

In S1004, the buffer control unit 412 determines whether the start-up timer 631 has timed out. If the start-up timer 631 has timed out, the buffer control unit 412 advances the process to S1005.

In S1005, the buffer control unit 412 starts the forward rotation of the pair of transport rollers 26. The buffer control unit 412 sets the rotation direction of the pair of transport rollers 26 to forward rotation by sending a command to the drive circuit 318. The drive circuit 318 starts the motor 344 in accordance with the command, and starts the forward rotation of the pair of transport rollers 26.

In S1006, the buffer control unit 412 determines whether the stop timer 633 has timed out. If the stop timer 633 has timed out, the buffer control unit 412 advances the process to S1007.

In S1007, the buffer control unit 412 starts the reverse rotation of the conveying roller pair 26. The buffer control unit 412 sends a command to the drive circuit 318 to stop the rotation of the conveying roller pair 26, set the rotation direction to reverse, and restart the motor 344. The buffer control unit 412 then advances the process to S1001.

In S1010, the buffer control unit 412 turns on the start timer 631, the inversion timer 632, and the stop timer 633. The predetermined time set in the start timer 631 is the time Twait required from the timing when the rear end of the sheet P2 is detected until the shift amount k between the sheets P1 and P2 reaches the predetermined amount kt. The predetermined time set in the inversion timer 632 is the time from the timing when the rear end of the sheet P2 is detected until the timing when the conveying roller pair 26 starts to invert. This causes the conveying roller pair 26 to rotate in synchronization with the conveying roller pair 24. The predetermined time set in the stop timer 633 is the time from the timing when the rear end of the sheet P2 is detected until the timing when the leading end (second end) of the sheet P2 reaches a position a predetermined distance Lstop away from the conveying roller pair 26.

In S1011, the buffer control unit 412 determines whether the start-up timer 631 has timed out. If the start-up timer 631 has timed out, the buffer control unit 412 advances the process to S1012.

In S1012, the buffer control unit 412 starts the forward rotation of the pair of conveying rollers 26. The buffer control unit 412 sets the rotation direction of the pair of conveying rollers 26 to forward rotation by sending a command to the drive circuit 318. The drive circuit 318 starts the motor 344 in accordance with the command, and starts the forward rotation of the pair of conveying rollers 26. In S1013, the buffer control unit 412 determines whether the reversal timer 632 has timed out. If the reversal timer 632 has timed out, the buffer control unit 412 advances the process to S1014.

In S1014, the buffer control unit 412 starts the reverse rotation of the conveying roller pair 26. The buffer control unit 412 sends a command to the drive circuit 318 to stop the rotation of the conveying roller pair 26, set the rotation direction to reverse, and restart the motor 344.

In S1015, the buffer control unit 412 determines whether the stop timer 633 has timed out. If the stop timer 633 has timed out, the buffer control unit 412 advances the process to S1016.

In S1016, the buffer control unit 412 determines whether the sheet P that has passed through the pair of conveying rollers 24 is the final sheet based on the job information received from the video controller 301. If the sheet P is not the final sheet, the buffer control unit 412 advances the process to S1017. On the other hand, if the sheet P is the final sheet, the buffer control unit 412 advances the process to S1021.

In S1017, the buffer control unit 412 stops the rotation of the conveying roller pair 26. The buffer control unit 412 stops the rotation of the conveying roller pair 26 by sending a command to the drive circuit 318. After that, the buffer control unit 412 advances the process to S1001.

At S1021, the buffer control unit 412 restarts the stop timer 633. At S1022, the buffer control unit 412 determines whether the stop timer 633 has timed out. If the stop timer 633 has timed out, the buffer control unit 412 advances the process to S1023.

In S1023, the buffer control unit 412 stops the rotation of the conveying roller pair 26. The buffer control unit 412 stops the rotation of the conveying roller pair 26 by sending a command to the drive circuit 318.

[Shift amount kt]
The shift amount kt is necessary for the post-processing unit 71 to correctly align the sheet stack. This is due to the alignment method using the half-moon roller 33.

Figures 11(A) to 11(F) show a method of aligning sheet P using the half-moon roller 33. Figure 11(A) shows that sheets P1 and P2 are transported to the post-processing section 71 with the target shift amount kt. In this case, when the half-moon roller 33 rotates, as shown in Figure 11(B), the half-moon roller 33 abuts against sheet P1 and transports it. Sheet P1 hits the alignment reference plate 39 and is aligned vertically.

As the half-moon roller 33 continues to rotate, as shown in FIG. 11C, the half-moon roller 33 contacts and transports sheet P2. As a result, sheet P2 also hits the alignment reference plate 39 and is aligned vertically. Thus, the alignment of sheets P1 and P2 forming the sheet stack W is completed.

On the other hand, as shown in FIG. 11(D), the amount of shift of sheets P1 and P2 may be smaller than the target amount kt. Or, as shown in FIG. 11(E), if the amount of shift is negative, the leading edge (second edge) of sheet P2 will precede the leading edge (second edge) of sheet P1. In these cases, as shown in FIG. 11(F), the half-moon roller 33 rotates in contact with sheet P2 without contacting sheet P1. As a result, only sheet P2 abuts against the alignment reference plate 39, without sheet P1 abutting against the alignment reference plate 39. As a result, misalignment of sheets P1 and P2 occurs. Therefore, the amount of shift is set to the target amount kt.

[Jam Clearance]
12A to 12C are diagrams for explaining jam processing. Note that FIG. 12C will be described in detail in Example 2. FIG. 12A shows that a jam has occurred in the sheet stack W1 being transported to the post-processing section 71. At this time, the following sheets P1 to P3 are present in the buffer section 81. Furthermore, the following sheets P4 and P5 are present in the horizontal transport section 14.

As shown in FIG. 12A, the image forming apparatus 1 has a maintenance door 1201 that can be opened and closed in the X1 direction. By opening the maintenance door 1201, the user can remove the sheet P that is stuck in the horizontal conveying section 14.

The post-processing device 4 has a maintenance door 1202 and a maintenance door 1203. The maintenance door 1202 is a door through which a user can access the buffer section 81. The user can remove a sheet P that is stuck in the buffer section 81 by opening the maintenance door 1202. The maintenance door 1202 can be opened and closed by rotating around a virtual axis Z1. The maintenance door 1203 is a door through which a user can access the post-processing section 71. The user can remove a sheet P that is stuck in the post-processing section 71 by opening the maintenance door 1203. The maintenance door 1203 can be opened and closed by rotating around a virtual axis Z2.

Normally, when a jam occurs, the transport operation of the sheet P must be stopped immediately in the area where the jam occurred. There is a possibility that some abnormality has occurred in the transport mechanism or the sheet P in the area where the jam occurred. If the transport operation is continued, there is a possibility that the jam situation will worsen. Therefore, when a jam occurs, the transport operation is stopped immediately.

As shown in FIG. 12A, if a jam occurs in the sheet bundle W1 downstream of the bundle creation unit 60, such as in the post-processing unit 71, the buffer unit 81 and horizontal transport unit 14 upstream of the post-processing unit 71 are stopped, and the transport of sheets P1 to P5 is stopped. The jam processing unit 415 notifies the video controller 301 that a jam has occurred in the post-processing unit 4, and stops the image forming device 1. This prevents sheets P from being fed into the post-processing unit 4. In this case, all transport operations are stopped immediately when a jam is detected. Therefore, the positions of sheets P1 to P5 thereafter match the positions of sheets P1 to P5 immediately after the jam was detected.

After the transport operation stops, the display device 5 displays a message informing the user that a jam has occurred and urging the user to remove sheet P. When the transport operation stops in the situation shown in FIG. 12(A), the user is required to perform the following operations. That is, the user needs to open the maintenance door 1201 and remove sheets P4 and P5.

Furthermore, the user must open the maintenance door 1202 to remove sheets P1 to P3. The leading edges of sheets P2 and P3 are exposed to the outside from the discharge port 54. Therefore, the user can also pull out sheets P2 and P3 from the post-processing device 4 without opening the maintenance door 1202.

The user must then open the maintenance door 1203 and remove the sheet stack W1 from the post-processing section 71. Although not shown in FIG. 12A, if additional sheets P are still remaining inside the image forming apparatus 1, they must also be removed via the door of the image forming apparatus 1.

As described above, if a jam occurs downstream of the image forming unit of the image forming device 1, the user must perform many tasks to remove the sheet P, and the time required to recover the image forming system 100 is also long. Therefore, the first embodiment solves such problems.

That is, as shown in FIG. 12(A), when a jam of sheet stack W1 occurs in the post-processing unit 71, the jam processing unit 415 immediately stops the transport operation of the post-processing unit 71. Furthermore, the jam processing unit 415 notifies the video controller 301 that a jam has occurred inside the post-processing device 4, and stops the image forming device 1. Furthermore, the jam processing unit 415 continues transporting sheets P1 to P5 in the buffer unit 81 and horizontal transport unit 14, which are upstream of the position where the jam occurred, and also continues the buffering operation of the buffer unit 81. As a result, as shown in FIG. 12(B), sheets P1 to P5 are buffered in the buffer unit 81 to form sheet stack W2. After that, all transport operations are stopped.

Then, the user opens the maintenance door 1203 to remove sheet stack W1, and opens the maintenance door 1202 to remove sheet stack W2. Note that the leading edge of sheet stack W2 protrudes from the discharge port 54 to the outside. Therefore, the user can pull out sheet stack W2 without opening the maintenance door 1202.

In other words, the user does not need to open the maintenance door 1201, the maintenance door 1202, or the door of the image forming apparatus 1. This reduces the amount of work for the user and shortens the time required to recover the image forming system 100.

Figure 13 is a flowchart showing the jam processing executed by the CPU 308 (jam processing unit 415).

In S1301, the jam processing unit 415 determines whether a jam has occurred inside the post-processing device 4. The jam detection unit 511 of the jam processing unit 415 detects the occurrence of a jam based on the detection results of the sheet sensors 27, 38, and 52. The jam position determination unit 512 identifies the position where the jam has occurred based on the detection results of the jam detection unit 511. For example, when the sheet sensor 27 or the sheet sensor 38 detects a jam, the jam position determination unit 512 determines that a jam has occurred inside the post-processing device 4. When a jam has occurred inside the post-processing device 4, the jam processing unit 415 advances the process to S1302.

In S1302, the jam processing unit 415 (message creation unit 514) notifies the video controller 301 of the occurrence of a jam. This causes the video controller 301 to stop the printing operation of the image forming device 1.

In S1303, the jam processing unit 415 determines whether the jam has occurred downstream of the buffer unit 81. When the sheet sensor 38 detects a jam, the jam position determination unit 512 of the jam processing unit 415 determines that the jam has occurred downstream of the buffer unit 81. If the jam has occurred downstream of the buffer unit 81, the jam processing unit 415 advances the process to S1304. If the jam has occurred upstream of the buffer unit 81 (bundle creation unit 60), the jam processing unit 415 advances the process to S1320. A jam occurring upstream of the buffer unit 81 (bundle creation unit 60) refers to a case where the sheet sensor 27 or the sheet sensor 52 detects a jam.

When a jam occurs downstream of the buffer unit 81, in step S1304, the jam recovery unit 415 stops the post-processing unit 71. For example, the jam recovery unit 415 stops the motors 345 to 349.

In S1305, the jam processing unit 415 determines whether the buffering operation of the sheet P transported to the buffer unit 81 is complete. The jam processing unit 415 determines that the buffering operation is complete when a predetermined time has elapsed since the rear end of the sheet P passed the sheet sensor 27. When the buffering operation is complete, the jam processing unit 415 advances the process to S1306.

In S1306, the jam processing unit 415 determines whether there is a subsequent sheet P being transported to the buffer unit 81 from the horizontal transport unit 14, which is upstream of the buffer unit 81, and the image forming device 1. The presence of a subsequent sheet P can be determined from the job information. If there is a subsequent sheet P, the jam processing unit 415 advances the process to S1305. If there is no subsequent sheet P, the jam processing unit 415 advances the process to S1307.

In S1307, the jam recovery unit 415 stops the buffer unit 81 and the horizontal conveying unit 14. That is, the jam recovery unit 415 stops the motors 341 to 344 and the motor 350. As shown in FIG. 3F and FIG. 12B, the sheet stack W2 stops while being sandwiched between the conveying roller pair 24. Therefore, the leading edge of the sheet stack W2 is exposed to the outside from the discharge port 54.

In S1308, the jam processing unit 415 prompts the user to remove the sheet bundle from the buffer unit 81. The message creation unit 514 of the jam processing unit 415 creates a message indicating that a jam has occurred and the user's procedure for removing the sheets P, and displays the message on the display device 5. Here, the sheets P that were upstream of the buffer unit 81 by S1305 and S1306 are buffered in the buffer unit 81 and become the sheet bundle W2. The leading edge of the sheet bundle W2 is exposed from the discharge port 54. Therefore, the user is requested to pull out the sheet bundle W2.

In S1309, the jam processing unit 415 prompts the user to open the door of the post-processing unit 71. For example, the message creation unit 514 may create a message prompting the user to open the maintenance door 1203 and remove the sheet P from the post-processing unit 71, and display the message on the display device 5. S1309 may be executed before S1308, or S1308 and S1309 may be executed simultaneously.

If a jam occurs upstream of the buffer unit 81, in S1320 the jam recovery unit 415 stops the buffer unit 81 and the horizontal transport unit 14. That is, the jam recovery unit 415 stops the motors 341 to 344 and the motor 350. The post-processing unit 71, which is downstream of the jam occurrence position, can continue the transport operation.

In S1321, the jam processing unit 415 determines whether post-processing and discharge of the sheet stack W in the post-processing unit 71 is complete. When discharge of the sheet stack from the post-processing unit 71 is complete, the jam processing unit 415 advances the process to S1322.

In S1322, the jam recovery unit 415 stops the post-processing unit 71. For example, the jam recovery unit 415 stops the motors 345 to 349.

In S1323, the jam processing unit 415 prompts the user to open the door of the buffer unit 81. For example, the message creation unit 514 creates a message indicating that a jam has occurred and a message prompting the user to open the maintenance door 1202, and displays them on the display device 5. Furthermore, the message creation unit 514 displays a message on the display device 5 indicating the procedure for the user to remove the sheet stack W from the buffer unit 81.

In S1324, the jam processing unit 415 prompts the user to open the door of the horizontal conveying unit 14. For example, the message creation unit 514 creates a message prompting the user to open the maintenance door 1201 and remove the sheet P from the horizontal conveying unit 14, and displays the message on the display device 5. S1324 may be executed before S1323, or S1323 and S1324 may be executed simultaneously.

According to the first embodiment, it becomes easy for the user to clear jams without providing an internal tray dedicated to jam clearance. For example, if the jam occurs downstream of the buffer unit 81, the buffering operation of the subsequent sheets P continues and a sheet stack W2 is created. The leading edge of the sheet stack W2 is exposed to the outside. Therefore, the user can remove all the sheets P upstream of the buffer unit 81 at once without opening the maintenance door 1202. This reduces the burden on the user when a jam occurs. The recovery time of the image forming system 100 is shortened.

Example 2
In the first embodiment, when a jam occurs, the shift amount k of the sheet bundle W2 created in the bundle creation unit 60 is set to a predetermined value kt. In the second embodiment, the shift amount k of the sheet bundle W2 is reduced. For example, the shift amount k may be set to 0. As a result, as shown in FIG. 12C, the leading edges of the multiple sheets P1 to P5 forming the sheet bundle W3 are aligned. When the leading edges of the multiple sheets P1 to P5 are aligned in this way, it becomes easier for the user to grasp the sheet bundle W3 and to pull out the sheet bundle W3.

As shown in FIG. 5, the jam processing unit 415 has a shift amount determination unit 515. When a jam occurs downstream of the buffer unit 81, the shift amount determination unit 515 reduces the shift amount k from kt to zero and causes the post-processing device 4 to form the sheet bundle W3.

The shift amount k is managed by the time Twait, which defines the timing when the pair of conveying rollers 26 start to reverse during buffer operation.

Figure 14 (A) shows the positions of sheets P1 and P2 at the moment when the rear end of sheet P2 is detected by sheet sensor 27. Distance L1 is the transport distance from sheet sensor 27 to transport roller pair 24. Distance L2 is the distance from the stopping position of the leading edge (second edge) of sheet P1 to transport roller pair 24.

At time t0, the rear end of sheet P2 passes through the sheet sensor 27. At time t1, a predetermined time Twait has elapsed from time t0. At this time t1, the pair of conveying rollers 26 starts to rotate in the reverse direction. As a result, sheet P1 is conveyed in the direction F2.

Figure 14 (B) shows the positions of sheets P1 and P2 at timing t2. Timing t2 is the timing when the transport speed of sheet P1 and sheet P2 held by the transport roller pair 26 become equal. The time from timing t0 to timing t2 is represented as Tmerge. At this point, the shift amount k is the target value kt. Note that distance X1 is the distance that the rear end of sheet P2 advances from timing t0 to timing t2. Distance X2 is the distance that the rear end of sheet P2 advances from timing t0 to timing t2.

Figure 14 (C) shows the relationship between the transport speed of sheets P1 and P2 and elapsed time. The vertical axis shows the transport speed. The horizontal axis shows the elapsed time. Timing t0 corresponds to the situation shown in Figure 14 (A). Timing t2 corresponds to the situation shown in Figure 14 (B). Time Tacc is the time from timing t1 to timing t2. In other words, time Tacc represents the time required for the stopped sheet P1 to reach transport speed V2.

The distance X2 that sheet P1 travels from the state in FIG. 14(A) to the state in FIG. 14(B) is the distance that sheet P1 travels from timing t1 to timing t2 in FIG. 14(C).

X2=(V2×Tacc)/2 (1)
A distance X1 that the sheet P2 travels from the state in FIG. 14A to the state in FIG. 14B is the distance that the sheet P2 travels from timing t0 to timing t2.

X1=V2×Tmerge (2)
The following formula is established based on the positional relationship between the sheets P1 and P2 at the timing t2.

L1-X1=L2-X2-kt (3)
By rearranging equations (1) to (3), the following equation is obtained.

L1-L2+kt=V2×Tmerge-(V2×Tacc)/2 (4)
As shown in FIG. 14C, the formula (5) holds true.

Tmerge = Twait + Tacc ... (5)
By rearranging equations (4) and (5) and substituting the normal target value kt with the shift amount k, the following equation is obtained.

Twait=2×(L1−L2+k)/V2−Tacc/2 (6)
The shift amount determination unit 515 can control the time Twait by setting the shift amount k in formula (6). That is, when a jam occurs downstream of the buffer unit 81, the shift amount determination unit 515 substitutes zero for the shift amount k in formula (6) to calculate the time Twait. The buffer control unit 412 obtains timing t2 according to the time Twait, and starts reverse rotation of the conveying roller pair 26 at timing t2. As a result, the shift amount k between the sheets P1 and P2 becomes zero.

According to the second embodiment, when a jam occurs downstream of the buffer unit 81, the shift amount k is reduced, and the sheet bundle W3 is created in the bundle creation unit 60. The leading edges of the multiple sheets P1 to P5 contained in the sheet bundle W3 are aligned. This makes it easier for the user to remove the sheet bundle W3 from the post-processing device 4 when clearing the jam.

Example 3
In the first and second embodiments, when a jam occurs downstream of the buffer unit 81, the sheets P1 to P5 remaining in the buffer unit 81 and upstream thereof form a sheet bundle W3, which is held in the bundle forming unit 60. As shown in Figures 12B and 12C, the leading end of the sheet bundle W3 is exposed to the outside from the discharge port 54. This allows the user to pull out the sheet bundle W3 without opening the maintenance door 1202.

Normally, the sheet P that was being transported inside the image forming system 100 when the jam occurred is discarded. After the image forming system 100 recovers, the page corresponding to the discarded sheet is printed again. Therefore, the above-mentioned sheet stack W3 becomes unnecessary. When the sheet stack W3 is discharged to the upper tray 25, there is an advantage that the user does not need to pull it out. However, if a preceding sheet P or sheet stack W0 is already present on the upper tray 25, the sheet stack W3 and the preceding sheet P or sheet stack W0 will be mixed together. In this case, the user must distinguish or sort the normal sheet P or sheet stack W0 from the sheet stack W3. This may impair user convenience.

Therefore, in the third embodiment, the preceding sheet determination unit 513 determines whether a preceding sheet P or sheet bundle W0 is present on the upper tray 25. The discharge method determination unit 516 determines the discharge method for the sheet bundle W3 depending on the result of the determination of whether a preceding sheet P or sheet bundle W0 is present on the upper tray 25.

As shown in FIG. 15A, if there is no preceding sheet P or sheet stack W0 on the upper tray 25, the sheet stack W3 is completely discharged onto the upper tray 25. This eliminates the need for the user to pull out the sheet stack W3.

As shown in FIG. 15B, when a preceding sheet P or sheet bundle W0 is present on the upper tray 25, the sheet bundle W3 is not loaded on the upper tray 25 and is held by the conveying roller pair 24 of the buffer section 81. This prevents the preceding sheet bundle W0 and the sheet bundle W3 from being mixed on the upper tray 25. In other words, the user is not required to sort the sheet bundle W3 from the preceding sheet P or sheet bundle W0.

Figure 16 is a flowchart showing the process of determining the discharge method for sheet bundle W3 when a jam occurs. Note that the following process can be executed after S1305.

In S1601, the CPU 308 (preceding sheet determination unit 513) determines whether or not there is a preceding sheet P (sheet stack W0) on the upper tray 25 based on the detection result of the sheet sensor 51. If there is a preceding sheet P (sheet stack W0), the CPU 308 advances the process to S1602. If there is no preceding sheet P (sheet stack W0), the CPU 308 advances the process to S1611.

In S1602, the CPU 308 (discharge method determination unit 516) determines that the discharge method is to hold the sheet bundle W3 in the bundle creation unit 60. As a result, the conveying roller pair 24 stops while holding the sheet bundle W3.

In S1611, the CPU 308 (discharge method determination unit 516) determines that the discharge method is to discharge the sheet stack W3 onto the upper tray 25. As a result, the conveying roller pair 24 discharges the sheet stack W3 onto the upper tray 25.

According to the third embodiment, if there is no preceding sheet P (sheet bundle W0) on the upper tray 25, the sheet bundle W3 is discharged to the upper tray 25. This eliminates the need for the user to pull out the sheet bundle W3. On the other hand, if there is a preceding sheet P (sheet bundle W0) on the upper tray 25, the sheet bundle W3 is held in the bundle creation section 60. Therefore, the preceding sheet bundle W0 and the sheet bundle W3 are not mixed on the upper tray 25. In other words, it is unnecessary for the user to separate the sheet bundle W3 from the preceding sheet P or sheet bundle W0.

<Technical ideas derived from Examples 1 to 3>
[Item 1]
a first conveying means for conveying a plurality of sheets entering from an entrance in order;
a bundle forming means for stacking the plurality of sheets conveyed by the first conveying means to form a sheet bundle;
a second conveying means for conveying the sheet bundle from the bundle forming means;
a post-processing unit that performs post-processing on the sheet bundle conveyed by the second conveying unit;
a discharge means for discharging the sheet bundle that has been subjected to the post-processing by the post-processing means;
a control means for controlling the first conveying means, the bundle forming means, the second conveying means, the post-processing means, and the discharge means,
The control means
determining whether a jam has occurred on the upstream side or downstream side of the bundle forming means in a conveying direction of the sheet;
when the jam occurs downstream of the bundle forming means, the second conveying means, the post-processing means and the discharging means are stopped from operating, while the first conveying means continues to convey the sheets to the bundle forming means, causing the bundle forming means to form a sheet bundle for external discharge;
A sheet processing device that, when a jam occurs upstream of the bundle creating means, stops operation of the first conveying means and the bundle creating means, while continuing transport of sheets to the bundle creating means by the second conveying means, operation of the post-processing means, and operation of the discharge means.

In this way, the bundle creation means that creates a bundle of sheets for the post-processing means also serves as the holding means that holds the sheets that have accumulated due to a jam. This makes it possible for the user to easily clear jams without having to provide an internal tray dedicated to jam clearance.

The inlet roller 21 is an example of a first conveying means. The bundle forming unit 60 and the buffer unit 81 are an example of a bundle forming means. The pair of conveying rollers 28, 29 is an example of a second conveying means. The post-processing unit 71 is an example of a post-processing means. The main control unit 303 and the CPU 308 function as a control means.

[Item 2]
a first tray capable of stacking a sheet bundle discharged from a discharge port of the bundle forming means;
a second tray capable of stacking the sheet bundle discharged from the discharge means,
2. The sheet processing apparatus according to claim 1, wherein, when the jam occurs downstream of the bundle creating means, the control means stops the transport of the sheet bundle for external discharge by the bundle creating means in a state in which a portion of the sheet bundle for external discharge protrudes from the discharge outlet and another portion of the sheet bundle for external discharge remains in the bundle creating means.

In this way, a portion of the sheet stacks W2, W3 for external discharge protrudes from the discharge port 54, while the other portions of the sheet stacks W2, W3 remain in the stack creating means. This allows the user to pull out the sheet stacks W2, W3 without opening the maintenance door 1202. The upper tray 25 is an example of a first tray. The lower tray 37 is an example of a second tray.

[Item 3]
a first tray capable of stacking a sheet bundle discharged from a discharge port of the bundle forming means;
a second tray capable of stacking the sheet bundle discharged from the discharge means,
3. The sheet processing apparatus according to claim 1, wherein the control unit controls the bundle forming unit so that the sheet bundle for external discharge is discharged to the first tray when the jam occurs downstream of the bundle forming unit.

This allows the user to avoid opening the maintenance door 1202 and removing the sheet stacks W2 and W3. This will greatly improve the usability of jam removal.

[Item 4]
a first tray capable of discharging a sheet bundle from a discharge port of the bundle forming means;
a second tray capable of discharging the sheet stack from the discharge means;
a detection unit that detects whether a sheet conveyed prior to the sheet stack to be discharged to the outside is present on the first tray,
The control means
when the jam occurs downstream of the bundle forming means and the previously transported sheet is present in the first tray, the bundle forming means stops transport of the bundle of sheets to be discharged to the outside in a state in which a portion of the bundle of sheets to be discharged to the outside protrudes from the discharge port and another portion of the bundle of sheets to be discharged to the outside remains in the bundle forming means,
3. The sheet processing device according to claim 1, further comprising: a first tray that receives the first sheet from the first tray and a second tray that receives the first sheet from the first tray;

In this way, when a preceding sheet is present in the first tray, the sheet bundles W2 and W3 for external discharge are prevented from being mixed with the preceding sheet. Therefore, the user does not need to separate the sheet bundles W2 and W3 for external discharge from the preceding sheet. When no preceding sheet is present in the first tray, the sheet bundles W2 and W3 for external discharge are discharged to the first tray. This eliminates the need for the user to open the maintenance door 1202 and to pull out the sheet bundles W2 and W3. This will greatly improve the usability of jam handling. Note that the sheet sensor 51 is an example of a detection means.

[Item 5]
the bundle creating means is configured to create a sheet bundle by overlapping a succeeding sheet on a preceding sheet,
The control means
when no jam has occurred, the bundle forming means is controlled so that a leading edge of the preceding sheet in the sheet bundle is positioned ahead of a leading edge of the succeeding sheet in a direction from the bundle forming means to the post-processing means;
5. A sheet processing apparatus according to any one of items 1 to 4, wherein, when a jam occurs, the bundle forming means is controlled so that the leading edge of the preceding sheet in the sheet bundle is aligned with the leading edge of the succeeding sheet in the direction from the bundle forming means to the post-processing means.

As shown in FIG. 12C, the sheet stack W3 may be created so that the leading edge of the preceding sheet is positioned ahead of the leading edge of the succeeding sheet. This may make it easier for the user to pull out the sheet stack W3.

[Item 6]
The sheet processing apparatus according to any one of items 1 to 5, wherein the control means notifies a sheet transporting device connected upstream of the sheet processing apparatus that the jam has occurred, and causes a display means of the sheet transporting device to display a message indicating that the jam has occurred.

This will allow the user to visually understand that a jam has occurred, and will also help the user understand that they need to clear the jam.

[Item 7]
7. The sheet processing apparatus according to item 6, wherein the message includes information prompting the user to pull out the sheet bundle for external discharge from a discharge port of the bundle forming means.

This allows the user to understand that sheet stack W3 can be removed without opening the maintenance door 1202.

[Item 8]
A housing and
a first door provided in the housing and opened when removing sheets or sheet bundles remaining in the first conveying means and the bundle forming means;
a second door provided in the housing and opened when removing the sheets or sheet bundle remaining in the second conveying means, the post-processing means, and the discharge means,
The control means
when the jam occurs at the bundle forming means or on the upstream side of the bundle forming means, displaying on the display means a message prompting the user to open the first door and perform jam clearance;
8. The sheet processing apparatus according to claim 6, further comprising: when the jam occurs downstream of the bundle forming means, the display means displays a message prompting the user to open the second door and perform jam clearance.

This allows the user to understand where the jam has occurred and which door needs to be opened. In particular, if a jam has occurred in the buffer section 81 or the entrance rollers 21, the display device 5 displays a message urging the user to open the maintenance door 1202 and remove the sheet P. If a jam has occurred in the post-processing section 71, the display device 5 displays a message urging the user to open the maintenance door 1203 and remove the sheet P. This message may further include information urging the user to pull out the sheet bundles W2 and W3.

[Item 9]
The bundle creation means includes:
a first roller pair for conveying the sheet delivered from the first conveying means;
a second roller pair that can rotate in a normal direction and a reverse direction and can come into contact with and separate from the first roller pair;
a third roller pair that is rotatable in a normal direction and a reverse direction and that transfers the sheet bundle from the bundle forming means to the second conveying means,
the second roller pair receives the first sheet from the first roller pair by rotating in a forward direction, and delivers the first sheet to the third roller pair and separates the first sheet from the third roller pair by rotating in a reverse direction;
the third roller pair rotates forward to convey the first sheet to a predetermined position, and rotates reversely to return the first sheet to the second roller pair;
the second roller pair receives the first sheet returned from the third roller pair and also receives the second sheet from the first roller pair, and then comes into contact with the first roller pair and rotates forward to stack the first sheet and the second sheet to create a sheet bundle, and then rotates in the reverse direction to deliver the sheet bundle to the third roller pair;
the third roller pair is configured to rotate forward to deliver the sheet stack to the second conveying means,
9. The sheet processing apparatus according to any one of items 1 to 8, wherein when a jam occurs downstream of the bundle forming means, the control means stops rotation of the second roller pair in a state in which a portion of the sheet bundle is exposed from an outlet of the bundle forming means.

As illustrated in Figures 7(A) to 7(H), the conveying roller pair 22 is an example of a first roller pair. The conveying roller pair 24 is an example of a second roller pair. The conveying roller pair 26 is an example of a third roller pair. The CPU 308 may control multiple roller pairs to switch back the sheet P and create a sheet bundle. Note that the switchback operation is merely one example of a method for creating a sheet bundle, and other creation methods may be used.

[Item 10]
the first conveying means has a detection means for detecting a sheet,
10. The sheet processing apparatus according to any one of items 1 to 9, wherein the control unit determines that a jam has occurred upstream of the bundle forming unit when the time during which the sheet is continuously detected by the detection unit exceeds a predetermined time.

The sheet sensor 27 is an example of a detection means. In this manner, a jam may be detected based on the passing time of the sheet P.

[Item 11]
11. The sheet processing apparatus according to any one of items 1 to 10, wherein the control means determines that a jam has occurred upstream of the bundle creating means when notified of the occurrence of a jam from a sheet conveying device connected upstream of the sheet processing apparatus.

In this way, the CPU 308 (jam detection unit 511) may determine that a jam has occurred upstream of the buffer unit 81 based on information notified by the video controller 301 of the image forming device 1.

[Item 12]
the second conveying means has a detection means for detecting a sheet,
12. The sheet processing apparatus according to any one of items 1 to 11, wherein the control unit determines that a jam has occurred downstream of the bundle forming unit when the time during which the sheet is continuously detected by the detection unit exceeds a predetermined time.

The sheet sensor 38 is an example of a detection means. In this manner, the sheet sensor 38 may be used to detect that a jam has occurred downstream of the bundle creation means.

[Item 13]
A conveying means for conveying a plurality of sheets;
a bundle forming means for stacking the plurality of sheets conveyed by the conveying means to form a sheet bundle;
a post-processing unit that performs post-processing on the sheet bundle created by the bundle creating unit;
a control means for controlling the conveying means and the bundle forming means to convey, when a jam occurs downstream of the bundle forming means, one or more sheets located upstream of the bundle forming means to the bundle forming means and to cause the bundle forming means to hold the one or more sheets;
A sheet processing apparatus comprising:

In this way, the bundle creation means that creates a bundle of sheets for the post-processing means also serves as the holding means that holds the sheets that have accumulated due to a jam. This makes it possible for the user to easily clear jams without having to provide an internal tray dedicated to jam clearance.

The inlet rollers 21 are an example of a conveying means. The bundle forming unit 60 is an example of a bundle forming means. The post-processing unit 71 is an example of a post-processing means. The main control unit 303 and the CPU 308 function as a control means.

[Item 14]
The bundle forming means has an outlet,
Item 14. The sheet processing apparatus according to item 13, wherein when a jam occurs downstream of the bundle creating means, the bundle creating means creates a sheet bundle by stacking one or more sheets located upstream of the bundle creating means, and holds the sheet bundle while leaving a portion of the sheet bundle exposed from the discharge outlet.

In this way, a portion of the sheet stacks W2 and W3 for external discharge protrudes from the discharge port 54, while the other portions of the sheet stacks W2 and W3 remain in the stack creating means. This allows the user to pull out the sheet stacks W2 and W3 without opening the maintenance door 1202.

[Item 15]
a first conveying means for conveying a plurality of sheets entering from an entrance in order;
a bundle forming means for stacking the plurality of sheets conveyed by the first conveying means to form a sheet bundle;
a second conveying means for conveying the sheet bundle from the bundle forming means;
a post-processing unit that performs post-processing on the sheet bundle conveyed by the second conveying unit;
a discharge unit that discharges the sheet stack that has been subjected to the post-processing by the post-processing unit,
determining whether a jam has occurred on the upstream side or downstream side of the bundle forming means in a conveying direction of the sheet;
when the jam occurs downstream of the bundle forming means, stopping the operations of the second conveying means, the post-processing means and the discharging means, while continuing the conveyance of the sheets to the bundle forming means by the first conveying means, thereby causing the bundle forming means to form a sheet bundle for external discharge;
when the jam occurs upstream of the bundle forming means, stopping the operations of the first conveying means and the bundle forming means, while continuing the conveyance of the sheet to the bundle forming means by the second conveying means, the operation of the post-processing means, and the operation of the discharge means;
A method for controlling a sheet processing apparatus having the same.

The invention is not limited to the above-described embodiment, and various modifications and variations are possible without departing from the spirit and scope of the invention. Therefore, the following claims are appended to disclose the scope of the invention.

21: Inlet roller, 81: Buffer section, 29: Pair of conveying rollers, 71: Post-processing section, 303: Main control section

Claims (15)

a first conveying means for conveying a plurality of sheets entering from an entrance in order;
a bundle forming means for stacking the plurality of sheets conveyed by the first conveying means to form a sheet bundle;
a second conveying means for conveying the sheet bundle from the bundle forming means;
a post-processing unit that performs post-processing on the sheet bundle conveyed by the second conveying unit;
a discharge means for discharging the sheet bundle that has been subjected to the post-processing by the post-processing means;
a control means for controlling the first conveying means, the bundle forming means, the second conveying means, the post-processing means, and the discharge means,
The control means
determining whether a jam has occurred on the upstream side or downstream side of the bundle forming means in a conveying direction of the sheet;
when the jam occurs downstream of the bundle forming means, the second conveying means, the post-processing means and the discharging means are stopped from operating, while the first conveying means continues to convey the sheets to the bundle forming means, causing the bundle forming means to form a sheet bundle for external discharge;
A sheet processing device that, when a jam occurs upstream of the bundle creating means, stops operation of the first conveying means and the bundle creating means, while continuing transport of sheets to the bundle creating means by the second conveying means, operation of the post-processing means, and operation of the discharge means. a first tray capable of stacking a sheet bundle discharged from a discharge port of the bundle forming means;
a second tray capable of stacking the sheet bundle discharged from the discharge means,
2. The sheet processing apparatus according to claim 1, wherein, when the jam occurs downstream of the bundle creating means, the control means stops the transport of the sheet bundle for external discharge by the bundle creating means in a state in which a portion of the sheet bundle for external discharge protrudes from the discharge outlet and another portion of the sheet bundle for external discharge remains in the bundle creating means. a first tray capable of stacking a sheet bundle discharged from a discharge port of the bundle forming means;
a second tray capable of stacking the sheet bundle discharged from the discharge means,
The sheet processing apparatus according to claim 1 , wherein the control unit controls the bundle forming unit so that the sheet bundle to be discharged to the outside is discharged to the first tray when the jam occurs downstream of the bundle forming unit. a first tray capable of discharging a sheet bundle from a discharge port of the bundle forming means;
a second tray capable of discharging the sheet stack from the discharge means;
a detection unit that detects whether a sheet conveyed prior to the sheet stack to be discharged to the outside is present on the first tray,
The control means
when the jam occurs downstream of the bundle forming means and the previously transported sheet is present in the first tray, the bundle forming means stops transport of the bundle of sheets to be discharged to the outside in a state in which a portion of the bundle of sheets to be discharged to the outside protrudes from the discharge port and another portion of the bundle of sheets to be discharged to the outside remains in the bundle forming means,
2. The sheet processing apparatus according to claim 1, further comprising: a stack forming means for controlling a stack of sheets to be discharged to the first tray when the jam occurs downstream of the stack forming means and when the previously transported sheets are not present in the first tray; the bundle creating means is configured to create a sheet bundle by overlapping a succeeding sheet on a preceding sheet,
The control means
when no jam has occurred, the bundle forming means is controlled so that a leading edge of the preceding sheet in the sheet bundle is positioned ahead of a leading edge of the succeeding sheet in a direction from the bundle forming means to the post-processing means;
2 . The sheet processing apparatus according to claim 1 , further comprising: a stack forming means for controlling a leading edge of the preceding sheet in the sheet stack to be aligned with a leading edge of the succeeding sheet in a direction from the stack forming means to the post-processing means when a jam occurs. The sheet processing device according to claim 1, wherein the control means notifies a sheet transport device connected upstream of the sheet processing device that the jam has occurred, and causes a display means of the sheet transport device to display a message indicating that the jam has occurred. The sheet processing device according to claim 6, wherein the message includes information prompting the user to pull out the sheet stack for external discharge from the discharge port of the stack creating means. A housing and
a first door provided in the housing and opened when removing sheets or sheet bundles remaining in the first conveying means and the bundle forming means;
a second door provided in the housing and opened when removing the sheets or sheet bundle remaining in the second conveying means, the post-processing means, and the discharge means,
The control means
when the jam occurs at the bundle forming means or on the upstream side of the bundle forming means, displaying on the display means a message prompting the user to open the first door and perform jam clearance;
The sheet processing apparatus according to claim 6 , wherein, when the jam occurs downstream of the bundle forming means, the display means displays a message prompting the user to open the second door and carry out jam clearance. The bundle creation means includes:
a first roller pair for conveying the sheet delivered from the first conveying means;
a second roller pair that can rotate in a normal direction and a reverse direction and can come into contact with and separate from the first roller pair;
a third roller pair that is rotatable in a normal direction and a reverse direction and that transfers the sheet bundle from the bundle forming means to the second conveying means,
the second roller pair receives the first sheet from the first roller pair by rotating in a forward direction, and delivers the first sheet to the third roller pair and separates the first sheet from the third roller pair by rotating in a reverse direction;
the third roller pair rotates forward to convey the first sheet to a predetermined position, and rotates reversely to return the first sheet to the second roller pair;
the second roller pair receives the first sheet returned from the third roller pair and also receives the second sheet from the first roller pair, and then comes into contact with the first roller pair and rotates forward to stack the first sheet and the second sheet to create a sheet bundle, and then rotates in the reverse direction to deliver the sheet bundle to the third roller pair;
the third roller pair is configured to deliver the sheet stack to the second conveying means by rotating in a forward direction,
2 . The sheet processing apparatus according to claim 1 , wherein the control means stops rotation of the second roller pair when a jam occurs downstream of the bundle forming means and a portion of the sheet bundle is exposed from an outlet of the bundle forming means. the first conveying means has a detection means for detecting a sheet,
2 . The sheet processing apparatus according to claim 1 , wherein the control unit determines that a jam has occurred upstream of the bundle forming unit when a time period during which the sheet is continuously detected by the detection unit exceeds a predetermined time period. The sheet processing device according to claim 1, wherein the control means determines that a jam has occurred upstream of the bundle creation means when a jam has occurred and is notified of the occurrence of a jam from a sheet transport device connected upstream of the sheet processing device. the second conveying means has a detection means for detecting a sheet,
2 . The sheet processing apparatus according to claim 1 , wherein the control unit determines that a jam has occurred downstream of the bundle forming unit when a time period during which the sheet is continuously detected by the detection unit exceeds a predetermined time period. A conveying means for conveying a plurality of sheets;
a bundle forming means for stacking the plurality of sheets conveyed by the conveying means to form a sheet bundle;
a post-processing unit that performs post-processing on the sheet bundle created by the bundle creating unit;
a control means for controlling the conveying means and the bundle forming means to convey, when a jam occurs downstream of the bundle forming means, one or more sheets located upstream of the bundle forming means to the bundle forming means and to cause the bundle forming means to hold the one or more sheets;
A sheet processing apparatus comprising: The bundle forming means has an outlet,
14. The sheet processing apparatus according to claim 13, wherein when a jam occurs downstream of the bundle creating means, the bundle creating means creates a sheet bundle by stacking one or more sheets located upstream of the bundle creating means, and holds the sheet bundle while leaving a portion of the sheet bundle exposed from the discharge outlet. a first conveying means for conveying a plurality of sheets entering from an entrance in order;
a bundle forming means for stacking the plurality of sheets conveyed by the first conveying means to form a sheet bundle;
a second conveying means for conveying the sheet bundle from the bundle forming means;
a post-processing unit that performs post-processing on the sheet bundle conveyed by the second conveying unit;
a discharge unit that discharges the sheet stack that has been subjected to the post-processing by the post-processing unit,
determining whether a jam has occurred on the upstream side or downstream side of the bundle forming means in a conveying direction of the sheet;
when the jam occurs downstream of the bundle forming means, stopping the operations of the second conveying means, the post-processing means and the discharging means, while continuing the conveyance of the sheets to the bundle forming means by the first conveying means, thereby causing the bundle forming means to form a sheet bundle for external discharge;
when the jam occurs upstream of the bundle forming means, stopping the operations of the first conveying means and the bundle forming means, while continuing the conveyance of the sheet to the bundle forming means by the second conveying means, the operation of the post-processing means, and the operation of the discharge means;
A method for controlling a sheet processing apparatus having the same.