JP2007269475A - Sheet post-handling device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet post-handling device and an image forming device equipped therewith having a configuration for improving the procedures required in the jammed state in an image forming system including the sheet post-handling device and the image forming device. <P>SOLUTION: In this sheet post-handling device B folding a sheet delivered from the image forming device A in Z shape and including first folding rollers 6, 7, 8 forming nip parts required for nipping a bent part of sheet bent by a first stop member 9 and a second stop member 10 and forming a fold and a first movable guide member 4 and a second movable guide member 12 for guiding sheets into the nip parts, a sheath-like storage conveyance passage 24 being deep in the vertical direction and being a sheet storage conveyance passage is provided separately from a conveyance passage 18, and the storage conveyance passage 24 stores all the sheets in the other conveyance passages 15, 16, 17 when jammed state occurs further in the other sheet post-handling device arranged on the downstream side. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention includes a sheet post-processing device that is a finisher device that performs sorting, stacking, binding, folding, saddle stitching, and the like of sheets (transfer paper) discharged from an image forming apparatus, and the sheet post-processing device. The present invention relates to an image forming apparatus.

2. Description of the Related Art A sheet post-processing apparatus that is disposed on the downstream side of an image forming apparatus such as a copying machine or a printer and performs processing such as binding on output recording paper is widely known. However, these functions have been multi-functional recently, and sheet post-processing apparatuses having a folding function such as bi-folding / Z-folding also exist (see, for example, Patent Documents 1 and 2).
In the future, as a further function, sheet post-processing apparatuses such as a folding apparatus and a bookbinding apparatus are connected in stages downstream from the image copying apparatus, and various systems are expected to be configured.
JP 2002-274749 A JP 05-119556 A

However, as such various systems are configured and the system itself becomes larger, there is a problem that the burden of the jam processing work when a jam occurs may increase.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sheet post-processing apparatus having a configuration for improving jam handling in an image forming system including the sheet post-processing apparatus and the image forming apparatus, and an image forming apparatus provided with the sheet post-processing apparatus. is there.

  In order to solve the above-described problem, the invention according to claim 1 is a sheet post-processing apparatus that performs a folding process on a sheet discharged from the image forming apparatus, wherein the sheet post-processing apparatus enters the folding processing conveyance path. First and second stop members provided to block the conveyance of the sheet, and a plurality of nip portions necessary for sandwiching the bent portion of the sheet bent by these stop members and forming a fold. A first folding roller, a second folding roller and a third folding roller, first and second movable guide members for guiding the sheet to the nip portions, and a paper discharge roller for discharging the folded sheet to the outside of the apparatus. And a control means, wherein a sheath-shaped accommodation conveyance path is provided on the upstream side of the sheet discharge roller, and the control means is provided downstream of the sheet post-processing apparatus. Other sea placed If a jam in the post-processing apparatus has occurred, and controls all the sheets in the other conveying path in the sheet post-processing apparatus so as to accommodate the sheath of the accommodating conveying path.

The invention according to claim 2 is characterized in that the sheet post-processing apparatus according to claim 1 conveys the sheet to the sheath-shaped accommodation conveyance path by driving the sheet discharge roller in the direction opposite to the sheet discharge direction. .
The invention according to claim 3 is characterized in that the sheet post-processing apparatus according to claim 1, wherein a trigger is provided by a paper discharge sensor provided in the vicinity of the paper discharge roller for the forward / reverse operation timing of the paper discharge roller. To do.
According to a fourth aspect of the present invention, when a jam occurs in another downstream sheet post-processing apparatus, the sheet in the image forming apparatus is received and the sheet is stacked on the sheath-shaped accommodation conveyance path. A sheet post-processing apparatus according to claim 1.
According to a fifth aspect of the present invention, there is provided an image forming apparatus in which the sheet post-processing apparatus according to any one of the first to fourth aspects is provided on the downstream side.

  According to the present invention, when a jam occurs in the downstream sheet post-processing apparatus by providing the accommodation conveyance path extending in a sheath shape in the vertical direction in the sheet post-processing apparatus that performs the Z-shaped folding process, All the sheets in the sheet post-processing apparatus that performs the folding process on the mold can be stacked on the accommodation conveyance path that extends in the form of a sheath in the vertical direction, and the jam handling performance can be improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration of a sheet post-processing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic circuit diagram illustrating control of the sheet post-processing apparatus and the image forming apparatus of FIG. In the following description, the sheet post-processing apparatus is assumed to be attached to the image forming apparatus.
In FIG. 1 and FIG. 2, in the sheet post-processing apparatus B, the recording paper (sheet) discharged from the image forming apparatus A is detected by the entrance sensor 1. The branching claw 2 is rotationally driven by a solenoid 23. When the solenoid 23 is on, the branch claw 2 moves to a straight conveyance position.

A PM motor (not shown) is used as a drive source for the first guide plate 4. The first folding roller 6 has an electromagnetic clutch (not shown) attached to its shaft. The first folding roller 6 rotates when the electromagnetic clutch is on, and the shaft rotates idly when the electromagnetic clutch is off.
The first shielding guide plate 9 is driven by a PM motor (not shown), and when the PM motor is rotated forward, the first shielding guide plate 9 moves to a position that closes the first conveyance path 16 indicated by a dotted line, Further, when the PM motor is rotated in the reverse direction, it moves to the solid line position where the sheet is conveyed to the first conveyance path 16.
A PM motor (not shown) is used to drive the second shielding guide plate 10. The second shielding guide plate 10 moves to a position that closes the third conveyance path 17 indicated by a dotted line when the PM motor is rotated forward, and the sheet is conveyed to the third conveyance path 17 when the PM motor is reversed. Move to (solid line position).

A PM motor (not shown) is used to drive the second guide plate 12. The first folding roller 6 has an electromagnetic clutch (not shown) attached to its shaft. The first folding roller 6 rotates when the electromagnetic clutch is on, and the shaft rotates idly when the electromagnetic clutch is off.
The entrance roller 21 and the paper discharge roller 27 are driven by a single stepping motor 28, and an electromagnetic clutch (not shown) is mounted on the roller shaft. The inlet roller 21 rotates when the electromagnetic clutch is on, and the shaft rotates idle when the electromagnetic clutch is off.
The first folding roller 6, the second folding roller 7, the third folding roller 8, the other conveying rollers 22, 26 and the like are driven by a single brushless motor 25. The brushless motor 25 can set the speed in two stages, i.e., when conveying a sheet to be Z-folded and conveying a sheet not subjected to the Z process.

As described above, the sheet post-processing apparatus B is attached to the side portion of the image forming apparatus A, and the sheet discharged from the image forming apparatus A is guided to the sheet post-processing apparatus B. First, the flow of sheets in the sheet post-processing apparatus B will be described.
When the folding operation is not performed, the bifurcating claw 2 is retracted downward to be conveyed straight, and is discharged through the discharge roller 27 as it is. When folding is selected, the sheet is guided and conveyed to the second conveyance path 15 by the branching claw 2 at the illustrated position.
When a sheet (not shown) enters the inside from the first conveyance path 15 and reaches the registration detection sensor 5, these sheets are further moved when the sheet advances further against the first guide plate 4 and the second guide plate 12. The PM motor is excited so that the guide plates 4 and 12 do not move, and the first folding is performed until the solenoid (electromagnetic clutch) 23 of the first folding roller 6 is turned on after Tms after the sheet reaches the registration detection sensor 5. Skew correction is performed at the nip portion of the roller 6 and the driven roller 6a, and then the sheet is conveyed to the second conveyance path 16.

The sheet conveyed to the second conveyance path 16 hits the first guide plate 4 and bends toward the nip portion between the first folding roller 6 and the second folding roller 7. As the sheet is further bent, the sheet is held in the nip portion of the roller pair of the first folding roller 6 and the second folding roller 7.
If the second folding is selected, the second shielding guide plate 10 is turned on, and the sheet is conveyed as it is toward the nip portion between the second folding roller 7 and the third folding roller 8.
If a mode other than the two-fold mode is selected, the sheet is conveyed to the third conveyance path 17. The sheet conveyed to the third conveyance path 17 hits the second guide plate 12 and bends near the nip portion between the second folding roller 7 and the third folding roller 8.
Further, the bent portion of the sheet is held in the nip portion of the roller pair of the second folding roller 7 and the third folding roller 8 and is conveyed toward the fourth conveyance path 18. Then, the sheet is conveyed from the fourth conveyance path 18 to the sheet discharge unit, and the sheet is discharged out of the apparatus by the sheet discharge roller 27, and the process ends.

Next, the movement of the first and second guide plates 4 and 12 will be described. When the information on the sheet size and the folding method is received from the image forming apparatus A, the first guide plate 4 and the second guide plate 12 move to the home position indicated by the solid line.
FIG. 1 further shows a first guide plate (HP) home position sensor 3, an arrival sensor 11, a second guide plate (HP) home position sensor 13, a paper discharge sensor 14, and a first shielding guide plate (HP) home position. A sensor 9, a second guide plate (HP) home position sensor 20, and a fifth conveyance path 24 extending in a sheath shape in the vertical direction are shown. In the control circuit of FIG. 2, the image forming apparatus control means, the sheet folding apparatus control means, and the bookbinding apparatus control means include CPUs 29, 30, and 31, respectively.

When the sheet output from the image copying apparatus A is a mixture of a sheet that is subjected to Z-folding and a sheet that is not to be output, all the sheets carried from the image copying apparatus A are conveyed to the second conveying path 15; When the arrival sensor 11 detects the leading edge of the sheet, the first shielding guide plate 9 and the second shielding guide plate 10 are respectively connected to the first conveyance path 16 and the third conveyance path 17 in the case of a sheet for which Z folding processing is performed. Move to a position to block.
In the case of a sheet not subjected to the Z-folding process, the first shielding guide plate 9 and the second shielding guide plate 10 are positioned at the home positions of the first conveyance path 16 and the third conveyance path 17 (dotted lines in FIG. 1). Therefore, the mixed output of the sheet that is Z-folded and the sheet that is not Z-folded is possible without reducing the productivity of the image copying apparatus A.

However, there is a difference in the time taken from the second conveyance path 15 outlet to the fourth conveyance path 18 due to the difference in conveyance path between the sheet that performs the Z-folding process and the sheet that does not perform the Z-folding process. This is because the sheet that performs the Z-folding process passes through the first conveyance path 16 and the third conveyance path 17, but the sheet that does not perform the Z-folding process passes through the first conveyance path 16 and the third conveyance path 17 without passing through the first conveyance path 16 and the third conveyance path 17. This is a result of direct conveyance from the second conveyance path 15 outlet to the fourth conveyance path 18.
For this reason, when a sheet that is not subjected to the Z-folding process is conveyed after the sheet that is subjected to the Z-folding process, the gap between the sheets is shortened and is conveyed to the downstream sheet post-processing apparatus as it is.
Therefore, when a sheet to be Z-folded is conveyed, when the sheet is conveyed to the inlet sensor 1, the inlet roller 21 is driven, and the sheet is secondly counted while counting the number of pulses of the driving stepping motor. When the sheet is conveyed to the conveyance path 15 and the sheet is nipped by the conveyance roller pair 22, the electromagnetic clutch mounted on the entrance roller 21 is turned off so that the sheet rotates idly. At this timing, the brushless motor switches the speed.

In the present invention, when a jam occurs in another sheet post-processing apparatus disposed further downstream of the sheet post-processing apparatus B, when a jam signal is received from the downstream sheet post-processing apparatus, the process up to the fourth conveyance path 18 is normally performed. When the leading edge of the sheet reaches the sheet discharge sensor 14, a sheet discharge motor (not shown) is rotated forward (driven in the sheet discharge direction) by an amount determined for each sheet size, and the sheet discharge roller pair 27 After stopping in a state where the sheet is nipped, the sheet is reversed to extend to the fifth conveyance path 24 that is a sheet containing conveyance path that extends in a sheath shape in the vertical direction or has a substantially U-shaped shape in the vertical direction. The sheet is conveyed.
This operation is repeated until all the sheets in the sheet post-processing apparatus B are conveyed to the fifth conveyance path 24. At this time, the sheets in the upstream image forming apparatus A are also carried in, and all the sheets are stacked on the fifth conveyance path 24.
As described above, the sheet can be conveyed to the deep substantially U-shaped conveyance path by reversing the sheet ejection motor that drives the sheet ejection roller, thereby improving the jam handling performance without increasing the cost due to the use of a new mechanism and parts. Obtainable.

  As described above, the sheet post-processing apparatus of the present invention performs the folding process on the sheet P discharged from the image forming apparatus A, and the sheet is fed into the conveyance path (16, 17) for the folding process. The first and second stop members 9 and 10 provided to block the conveyance, and a plurality of nip portions necessary for sandwiching the bent portion of the sheet bent by these stop members and forming a crease are formed. The first folding roller 6, the second folding roller 7 and the third folding roller 8, the first and second movable guide members 4 and 12 for guiding the sheet to each nip portion, and the sheet subjected to the folding process outside the machine A discharge roller 27 for discharging and a control means 30 are included. Further, a sheath-shaped accommodation conveyance path 24 is provided on the upstream side of the sheet discharge roller, and the control unit is configured to cause a jam in another sheet post-processing apparatus disposed downstream of the sheet post-processing apparatus. Then, control is performed so that all the sheets in the other conveyance paths in the sheet post-processing apparatus are accommodated in the sheath-shaped accommodation conveyance path 24.

FIG. 3 is a schematic diagram for explaining a first flow of a sheet entering the periphery of the folding roller. FIG. 4 is a schematic diagram for explaining a second flow of the sheet entering the periphery of the folding roller. FIG. 5 is a schematic diagram for explaining a third flow of the sheet entering the periphery of the folding roller.
The sheet P that has passed through the nip portion between the first folding roller 6 and the driven roller 6a (FIG. 3) hits the first guide plate 4 moving downward and is gradually bent (FIG. 4). If this bending becomes large, it will be caught in the nip part of the 1st folding roller 6 and the 2nd folding roller 7 (FIG. 5).

FIG. 6 is a schematic diagram for explaining a fourth flow of the sheet entering the periphery of the folding roller. FIG. 7 is a schematic diagram for explaining a fifth flow of the sheet entering the periphery of the folding roller. FIG. 8 is a schematic diagram for explaining the sixth flow of the sheet entering the periphery of the folding roller.
The sheet P, which is folded in place by the nip portion between the first folding roller 6 and the folding roller 7 (FIG. 6), is sent to the third conveyance path 17, hits the second guide plate 12, and is gradually bent (FIG. 7). ). When this deflection becomes large, it is held in the nip portion between the second folding roller 7 and the third folding roller 8 and sent to the fourth conveying path 18 (see FIG. 1) (FIG. 8).

  FIG. 9 is a schematic diagram illustrating how the sheet is folded on the first guide plate during Z-folding. FIG. 10 is a schematic diagram illustrating how the sheet is folded on the second guide plate during Z-folding. 9 and 10, the sheet is folded as illustrated in relation to the abutting surfaces of the first guide plate 4 and the second guide plate 10.

FIG. 11 is a flowchart illustrating a control flow when only the Z-folding process is performed.
With reference to FIG. 1, FIG. 2 and FIG. 11, it is determined whether or not the entrance sensor 1 (FIG. 1) is ON (S1). If it is on, driving of the transport motor 25 (FIG. 2) is started (S2). Next, it is determined whether or not the registration detection sensor 5 (FIG. 1) is on (S3). If it is on, skew correction is started and the motors (not shown) of the first and second guide plates 4 and 12 are excited (S4).
Next, it is determined whether or not the paper discharge sensor 14 is on (S5). If it is on, it is determined whether the jam flag is off (S6). If the jam flag is off, it is determined whether the paper discharge sensor 12 is off (S7). If it is off, the transport motor is stopped (S8). If the jam flag is on in step (S6), the operation proceeds to jam operation (S9).

FIG. 12 is a flowchart for explaining the operation of the first and second guide plates when a folding command is received from the image forming apparatus. Referring to FIGS. 1, 2 and 12, when a folding command is received from image forming apparatus A, it is determined whether or not first guide plate home position (HP) sensor 3 is on (S11).
If not, the motor (not shown) of the first guide plate 4 is driven in reverse (S12). If it is on, it is determined whether the second guide plate HP sensor 13 is on (S13). If not, the motor (not shown) of the second guide plate 12 is driven in reverse (S14).
If the second guide plate HP sensor 13 is on in step (S13), it is determined whether the first guide plate HP sensor 3 is on (S15). If it is on, the driving of the motor of the first guide plate 4 is stopped (S16). Next, it is determined whether the second guide plate HP sensor 13 is on (S17). If ON, the motor of the second guide plate 12 is driven in reverse (S18).

Next, it is determined whether or not the first and second guide plate HP sensors 3 and 13 are on (S19). If it is on, the first guide plate motor is driven in the forward direction as much as it moves to the standby position determined by the sheet size and folding method (S20).
Next, the motor of the second guide plate 12 is driven to rotate forward by the amount of movement to the standby position determined by the sheet size and folding method (S21). It is determined whether the motors of the first and second guide plates 4 and 12 are off (S22). If they are off, the folding preparation is completed.

FIGS. 13 and 14 are flowcharts for explaining the control when the Z-folding process and the normal processing sheet are mixed. With reference to FIGS. 1, 2, 13 and 14, first, it is determined whether or not the inlet sensor 1 is on (S31). If it is on, driving of an inlet motor (not shown) is started (S32).
It is determined whether or not the inlet motor is driven with a specified pulse (S33). If it is driven with a specified pulse, it is determined whether or not to perform a Z-folding process (S34). The drive is started at / second (S35). If the Z-folding process is not performed, the conveyance motor 25 starts to be driven at 800 mm / second (S36).
Thereafter, it is determined whether the arrival sensor 11 is on (S37). If it is on, it is determined whether the sheet is a Z-folding process execution sheet (S38). If it is a Z-folding process execution sheet, the first and second shielding guide plate HP sensors. It is determined whether 19 and 20 are on (S39).

If there is no Z-folding process execution sheet in step (S38), it is determined whether or not the first and second shielding guide plate HP sensors 19 and 20 are on (S40). The motor is driven forward (S41).
Next, it is determined whether or not the motor is driven with the designated pulse (S42). If the motor is driven with the designated pulse, the flow continues after the first and second shielding guide plate HP sensors 19 and 20 in step (S39) are turned on. Return to. If it is not on in step (S39), the motors of the first shielding guide plates 9 and 10 are driven in reverse (S43), and it is determined again whether the first and second shielding guide plate HP sensors 19 and 20 are on (step S39). S44).
If the first and second shielding guide plate HP sensors 19 and 20 in step (S39) are on, it is determined whether or not the registration detection sensor 5 (FIG. 1) is on (S45). If it is on, skew correction is started and the motors (not shown) of the first and second guide plates 4 and 12 are excited (S46).
Next, it is determined whether or not the paper discharge sensor 14 is on (S47). If it is on, it is determined whether the jam flag is off (S48). If the jam flag is off, it is determined whether the paper discharge sensor 12 is off (S49). If it is off, the transport motor is stopped (S50). If the jam flag is on in step (S48), the operation proceeds to jam operation (S51).

FIG. 15 is a schematic diagram illustrating a first flow of a sheet that is not subjected to Z-folding processing. FIG. 16 is a schematic diagram illustrating a second flow of a sheet that is not subjected to Z-folding processing. FIG. 17 is a schematic diagram illustrating a third flow of a sheet that is not subjected to Z-folding processing.
Referring to FIGS. 15 to 17, the sheet P that has passed through the nip portion between the first folding roller 6 and the driven roller 6 a (FIG. 15) hits the first shielding guide plate 9, and gradually approaches the first folding roller 6 and the first folding roller 6. It is directed to the nip portion of the two-fold roller 7 (FIG. 16). When the sheet P is further fed, it is picked up by the nip portion between the first folding roller 6 and the second folding roller 7 (FIG. 17).

FIG. 18 is a schematic diagram illustrating a fourth flow of a sheet that is not subjected to Z-folding processing. FIG. 19 is a schematic diagram illustrating a fifth flow of a sheet that is not subjected to Z-folding processing. FIG. 20 is a schematic diagram illustrating a sixth flow of a sheet that is not subjected to the sheet Z folding process.
18 to 20, the front end of the sheet P that has passed through the nip portion between the first folding roller 6 and the folding roller 7 (FIG. 18) hits the second shielding guide plate 10, and gradually the second folding roller 7 And directed toward the nip portion of the third folding roller 8 (FIG. 19). When the sheet P is further fed, it is picked up by the nip portion between the second folding roller 7 and the third folding roller 8 (FIG. 20) and sent to the fourth conveyance path 18 (not shown).

  FIG. 21 is a flowchart for explaining the jam signal reception monitoring operation. In FIG. 21, it is determined whether a jam signal is received from the downstream sheet post-processing apparatus (S61). If a jam signal is received, the jam flag is turned on (S62).

  FIG. 22 is a flowchart for explaining the control when a sheet jam occurs in the downstream sheet post-processing apparatus. In FIG. 22, a paper discharge motor (not shown) starts designated pulse forward rotation driving for each sheet size (S71). Next, it is determined whether or not the paper discharge motor is stopped (S72). If it is stopped, reverse rotation driving of the paper discharge motor is started (S73), and then it is determined whether or not the paper discharge motor is stopped. (S74) If it is stopped, the control is terminated.

1 is a schematic diagram illustrating an overall configuration of a sheet post-processing apparatus according to an embodiment of the present invention. FIG. 2 is a schematic circuit diagram illustrating control of the sheet post-processing apparatus and the image forming apparatus in FIG. 1. It is the schematic explaining the 1st flow of the sheet | seat which entered the folding roller periphery. It is the schematic explaining the 2nd flow of the sheet which entered the folding roller periphery. It is the schematic explaining the 3rd flow of the sheet which entered the folding roller periphery. It is the schematic explaining the 4th flow of the sheet | seat which entered the folding roller periphery. It is the schematic explaining the 5th flow of the sheet which entered the folding roller periphery. It is the schematic explaining the 6th flow of the sheet which entered the folding roller periphery. It is the schematic explaining how a sheet is folded by the 1st guide plate at the time of Z folding. It is the schematic explaining how to fold a sheet with the 2nd guide board at the time of Z folding. It is a flowchart explaining the control flow at the time of only Z folding processing. 10 is a flowchart for explaining the operation of the first and second guide plates when a folding command is received from the image forming apparatus. It is a flowchart (the 1) explaining the control at the time of Z folding process and a normal process sheet | seat mixed loading. It is a flowchart (the 2) explaining the control at the time of Z folding process and a normal process sheet | seat mixed loading. It is the schematic explaining the 1st flow of the sheet | seat which does not perform Z folding process. It is the schematic explaining the 2nd flow of the sheet | seat which does not perform Z folding process. It is the schematic explaining the 3rd flow of the sheet | seat which does not perform Z folding process. It is the schematic explaining the 4th flow of the sheet | seat which does not perform Z folding process. It is the schematic explaining the 5th flow of the sheet | seat which does not perform Z folding process. It is the schematic explaining the 6th flow of the sheet | seat which does not perform sheet Z folding process. It is a flowchart explaining jam signal reception monitoring operation. 10 is a flowchart illustrating control when a sheet jam occurs in a downstream sheet post-processing apparatus.

Explanation of symbols

A image forming apparatus B sheet post-processing apparatus 4 first movable guide member (first guide plate)
6 First folding roller 7 Second folding roller 8 Third folding roller 9 First stop member (first shielding guide plate)
10 Second stop member (second shielding guide plate)
12 Second movable guide member (second guide plate)
14 Paper discharge sensor 15 Transport path (second transport path)
16 transport path (first transport path)
17 Transport path (third transport path)
18 Transport path (4th transport path)
24 Sheath-shaped accommodation transport path (fifth transport path)
27 Paper discharge roller 29 CPU (for image forming apparatus control means)
30 CPU (for sheet folding device control means)

Claims (5)

A sheet post-processing apparatus that performs a folding process on a sheet discharged from an image forming apparatus, and includes a first and a second stop member provided to block conveyance of the sheet into a folding processing path. A first folding roller, a second folding roller, and a third folding roller that sandwich a bent portion of the sheet bent by these stop members and form a plurality of nip portions necessary to form a fold, and each of the nips In a sheet post-processing apparatus including first and second movable guide members that guide the sheet to a section, a discharge roller that discharges the folded sheet to the outside of the apparatus, and a control unit,
In the case where a jam occurs in another sheet post-processing apparatus disposed downstream of the sheet post-processing apparatus, a sheath-like accommodation conveyance path is provided on the upstream side of the paper discharge roller. In addition, the sheet post-processing apparatus is controlled so that all the sheets in the other conveyance paths in the sheet post-processing apparatus are accommodated in the sheath-shaped accommodation conveyance path.   The sheet post-processing apparatus according to claim 1, wherein the control unit conveys the sheet into the sheath-shaped accommodation conveyance path by driving the sheet discharge roller in the direction opposite to the sheet discharge direction.   2. The sheet post-processing apparatus according to claim 1, wherein a trigger is set by a paper discharge sensor provided in the vicinity of the paper discharge roller for the forward / reverse operation timing of the paper discharge roller.   The control unit receives a sheet in the image forming apparatus and stacks the sheet on the sheath-shaped accommodation conveyance path when a jam occurs in the other sheet post-processing apparatus. The sheet post-processing apparatus according to Item 1.   An image forming apparatus comprising: the sheet post-processing apparatus according to claim 1 provided on the downstream side.

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