JP2014218311A - Postprocessing device and image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a postprocessing device with a structure which ensures that pre-stacked paper are aligned at its rear end even if a staple tray is used in which rear end alignment using the fall of paper due to its own weight or by pushing the paper is difficult.SOLUTION: A postprocessing device comprises: a conveyance path for conveying paper P toward a staple tray 21 disposed opposite to binding means which is used for binding processing of the paper; a prestack conveyance path 4 which branches from the conveyance path and makes the paper wait for a while; end edge fences 24, 25 which are disposed on the staple tray 21 and strike against the end edge of the paper for end edge alignment; a return roller 41 which is disposed above the staple tray 21 near the end edge fences 24, 25 and moves the paper toward the end edge fences; and a conveyance auxiliary member 42 which is disposed at a position opposed to the return roller 41 across the paper and is smaller than the frictional force between paper sheets caused when the paper is moved by the return roller 41.

Description

  The present invention relates to a post-processing apparatus and an image forming system, and more particularly to a paper alignment mechanism for binding processing for paper after image formation.

  In addition to the case where paper such as recording paper printed out by an image forming apparatus such as a copier, printer or printing machine is discharged from the image forming apparatus, paper post-processing attached to the image forming apparatus In some cases, the device is discharged after being subjected to processing such as folding and binding processing.

In the binding process performed by the paper post-processing device, when the paper is conveyed one by one to the staple tray, the rear end of the paper in the paper conveyance direction by the return roller and the tapping roller that abuts the upper surface of the paper and can rotate in the direction opposite to the conveyance direction. The rim is abutted against the rear end fence located on the tray.
A sheet bundle whose rear end in the conveyance direction is abutted against the rear end fence is subjected to a stapling process after the rear ends of the sheets are aligned (for example, Patent Document 1).

On the other hand, there is known a pre-stack system in which a plurality of sheets are accumulated in a part of the apparatus and then re-conveyed toward a staple tray while the sheets are introduced one by one.
In this method, a plurality of sheets are collected in a conveyance path shorter than the introduction path of the staple tray and then re-conveyed toward the staple tray. Therefore, the conveyance time can be increased as compared with the case where the sheets are directly introduced into the staple tray. There is an advantage.
In the pre-stack method, a configuration is known in which the rear end of the sheet bundle is pushed toward the rear end fence by a discharge claw used when discharging the sheet bundle from the staple tray in order to align the rear end of the sheet bundle ( For example, Patent Document 2).
The sheet bundle that has been rear-end aligned by abutting the rear end against the rear-end fence is stapled and then discharged from the staple tray by the discharge claw described above.

The paper introduced into the staple tray is subjected to alignment processing in the vertical direction, that is, so-called vertical alignment by abutting the rear end against the rear end fence.
The vertical alignment is performed by dropping the paper by its own weight or by forcibly pushing the tip with the discharge claw described above.
However, the fall of the weight of the paper is affected by the inclined state of the staple tray, and the leading edge is not pushed and moved by the discharge claw unless the paper area up to the leading edge is placed on the staple tray.
In other words, if the length of the staple tray is not secured as the sheet stacking surface in the direction in which the sheets are vertically aligned, in other words, in the direction in which the sheets are introduced to the staple tray, the sheets protrude from the machine. The tip cannot be pushed and moved.

Moreover, if the inclination of the staple tray is not sufficient, the weight drop cannot occur.
In such a case, there is a case where a staple tray called a half tray provided when the post-processing apparatus is small is used.
A staple tray using a half tray will be described with reference to FIG. 1, but the inclination is relatively small and the length of the sheet stacking surface is short.
In such a half tray, it is difficult to expect the paper to fall by its own weight, and it is difficult to push it toward the rear end fence because the leading edge of the pushed paper may be out of the machine.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet post-processing apparatus having a configuration capable of reliably aligning the trailing edge of a pre-stacked sheet even when a staple tray in which trailing edge alignment is difficult to be performed by dropping or pushing the sheet by its own weight is used. And providing an image forming system.

  In order to achieve this object, the present invention provides a transport path for transporting a sheet toward a staple tray provided facing the binding means used for the sheet binding process, and the sheet is once branched from the transport path. A pre-stack conveyance path for waiting; an edge fence provided on the staple tray for abutting the edge of the paper to align the edge; and disposed above the staple tray in the vicinity of the edge fence. A post-processing apparatus provided with a hitting roller that moves toward the edge fence, between the sheets generated when the sheet is moved by the hitting roller at a position facing the hitting roller with the sheet interposed therebetween. In the post-processing apparatus, a conveyance auxiliary member smaller than the frictional force is provided.

  According to the present invention, since the conveyance auxiliary member is a member smaller than the frictional force between the sheets generated when the sheet is moved by the tapping roller, the sliding between the sheet and the staple tray when the tapping roller is operated. The sheet can be moved with the resistance reduced. As a result, even if the inclination of the staple tray is small and the leading edge of the sheet cannot be pushed and moved, the trailing edge of the sheet can be aligned only by using the hitting roller.

It is a schematic diagram for demonstrating the structure used for one Example of the post-processing apparatus which concerns on embodiment of this invention. It is a schematic diagram for demonstrating the principal part structure of the post-processing apparatus shown in FIG. It is a schematic diagram for demonstrating the other example regarding the principal part structure shown in FIG. It is a schematic diagram for demonstrating another example regarding the principal part structure shown in FIG. It is a block diagram for demonstrating the structure of the control part used for another Example of the post-processing apparatus which concerns on embodiment of this invention. It is a figure for demonstrating the principal part structure of the post-processing apparatus in which the control part shown in FIG. 5 is used. It is a figure explaining the case where the 1st sheet | seat is introduce | transduced aiming at the principal part structure of the post-processing apparatus shown in FIG. FIG. 8 is a diagram illustrating a prestack state of the first sheet illustrated in FIG. 7. It is a figure explaining the case where the 2nd sheet | seat is introduce | transduced in the state shown in FIG. FIG. 10 is a diagram illustrating an aspect related to a conveyance state between sheets from the state illustrated in FIG. 9. It is a figure which shows the state which pre-stacked two sheets from the state shown in FIG. FIG. 12 is a diagram illustrating a case where a third sheet is introduced in the state illustrated in FIG. 11. FIG. 13 is a diagram illustrating a merged state of the third sheet illustrated in FIG. 12 and two sheets that have been prestacked. FIG. 13 is a diagram illustrating a state in which three sheets are introduced into the staple tray in the state illustrated in FIG. 12. It is a figure which shows the state which the hitting roller act | operated in the state shown in FIG. FIG. 6 is a diagram illustrating a state in which three sheets are aligned with a rear end fence of a staple tray.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described based on illustrated embodiments.
FIG. 1 is a schematic diagram for explaining an image forming system using a sheet post-processing apparatus according to an embodiment of the present invention.
In FIG. 1, an image forming system 100 includes a sheet post-processing device 300 used for sheet processing continuously attached to and connected to a sheet discharge unit in an image forming apparatus 200 such as a copying machine, a printer, or a printing machine.

  The sheet post-processing device 300 used in the image forming system 100 has a function as a post-processing device that performs a folding process such as a binding process for binding a plurality of sheets together and a folding process.

In the image forming system 100, after an image is formed on the paper P in the image forming apparatus 200, the paper post-processing apparatus 300 receives the paper P from the image forming apparatus 200 and performs various post-processing on the received paper P.
Examples of the various post processes include an end binding process and a half-fold process. The half-folding process includes a saddle stitching process.

In the present embodiment, in the edge binding process and the saddle stitching process, the sheet post-processing apparatus 300 is attached to the image forming apparatus 200, and binding is performed using a part of a sheet bundle instead of using a needle.
The sheet post-processing apparatus 300 that performs such various post-processing has a discharge mode, an end binding mode, and a middle folding mode as operation modes.

The image forming apparatus 200 has a known configuration, and an example is an electrophotographic color image forming apparatus.
In the image forming apparatus 200, for example, a control unit, an image forming unit, an optical writing unit, a paper feeding unit, a paper feeding conveyance path, an image reading unit, an intermediate transfer unit, a fixing unit, a paper discharge conveyance path, a double-side conveyance path, and the like ( Neither is shown), and an image is formed on both sides or one side of the paper 5.

In FIG. 1, the principle structure of the sheet post-processing apparatus 300 will be described together with the operation as follows.
The sheet post-processing apparatus 300 is provided with an introduction path 1 for receiving the image-formed paper P discharged from the image forming apparatus and three paths branched from the introduction path 1.
The three paths include an upper transport path 2 toward the proof tray 6, a straight transport path 3 that performs shift processing, end binding, or two-point binding processing, and a lower transport path 4 that performs saddle stitching and folding processing. Yes.
An inlet roller 10 and an inlet sensor 13 are arranged in the introduction path 1, and it is detected by these sensors that the paper P is carried into the paper post-processing apparatus.

A transport roller front 11 is disposed downstream of the entrance roller 10. Further, the branching claws 7 and 8 positioned at the branching portion at the terminal end of the introduction path 1 rotate to sort the sheet transporting direction into the upper transporting path 2, the straight transporting path 3, and the lower transporting path 4. .
The straight conveyance path 3 is provided with a conveyance roller rear 12 positioned behind the branch claw 7 in the conveyance direction, and the sheet P is conveyed to the conveyance path 3 through this.
A paper discharge roller 26 and a paper discharge sensor 28 are arranged in the conveyance path 3.

  In the sort mode, the conveyance roller rear 12 having the shift mechanism is driven by a driving means (not shown). That is, when driven, the sheet P is moved by a certain amount in a direction perpendicular to the conveying direction during conveyance, whereby the sheet P is shifted by a certain amount, and discharged by the sheet discharge roller 26 toward the sheet discharge tray 5 and sequentially stacked. To go.

The paper discharge port to the paper discharge tray 5 has a pair structure in which a paper or a bundle of paper is sandwiched by a paper discharge roller 26 and a driven roller 27 and discharged.
This is because the discharge guide provided with the driven roller 27 with respect to the discharge roller 26 can be selectively moved between a closed state in which a sheet or a sheet bundle can be discharged and an unopened state in which the sheet is discharged. After the paper shift operation is completed, the paper is nipped and discharged.
Further, a filler 40 is disposed in the vicinity of the upper portion of the paper discharge port so as to freely rotate at a position near the center of the paper P when stacked, and the tip of the filler 40 is in contact with the upper surface of the paper P.
Near the base of the filler 40, there is an upper surface detection sensor (not shown) that detects the height position of the tip of the filler 40, and detects the paper surface height of the stack paper P by these.

When the upper surface detection sensor is turned on as the sheet height increases due to an increase in the number of sheets deposited on the discharge tray 5, the control unit 200 shown in FIG. 5 controls the drive means (not shown) of the discharge tray 5. The paper discharge tray 5 is lowered to maintain the paper surface height at a fixed position.
That is, when the upper surface detection sensor turns off when the discharge tray 5 is lowered after being raised, the lowering of the discharge tray 5 is stopped. This operation is repeated, and when the paper discharge tray 5 reaches the specified tray full height, a stop signal is issued from the sheet post-processing device to the image forming device to stop the image forming operation of the system.

A staple tray 21 is disposed in the transport path 3.
A return roller denoted by reference numeral 41 performs a pendulum motion and comes into contact with the paper, and the rear end, which is one of the paper edges, returns the paper toward the rear end fences 24 and 25 located in the vicinity of the edge fence. The vertical position of the sheet bundle is aligned by touching. The return roller 41 is also called a hitting roller because of the pendulum motion. In the following explanation, it is also called a hitting roller.
On the staple tray 21, a jogger fence 22, which is an edge fence that advances and retracts in a direction perpendicular to the paper surface and aligns the edges in the width direction of the paper P discharged onto the staple tray 21, 23 is provided.
By performing these two operations, the sheet bundle discharged on the staple tray 21 is aligned and stacked.
When the edge binding mode is selected, the stapled sheet 50 is moved in a direction perpendicular to the paper surface to staple the aligned sheet bundle at the appropriate position at the lower edge of the sheet bundle, and is discharged in the sheet discharge direction by the discharge claw 29. The paper discharge process is performed.

During the paper discharge, the paper discharge roller 26 and the driven roller 27 face each other so that the paper is nipped and conveyed, and a paper bundle is arranged on the paper discharge tray 5 to be discharged.
In the lower conveyance path 4, saddle stitch conveyance rollers 61, 62, 63 and a stapler 51 for saddle stitching are arranged.
When the sheets are conveyed to the saddle stitching position by these members, the binding process is performed at a predetermined position in the width direction.

The sheet that has been subjected to the saddle stitching process is conveyed to the sheet folding stopper 64 of the sheet folding section by the saddle stitch conveying rollers 62 and 63, and is folded by the sheet folding blade 71 and the middle folding plate 72. Is discharged to the middle folding tray 9.
The paper folding stopper 64 is a member that can move along the paper conveyance direction.
The position of the sheet folding stopper 64 is changed by the control unit 1000 described in FIG. 13 along a sheet conveyance direction via a stepping motor (not shown) as a drive source, and the moving speed at the time of the change is also changed. It is a member to be changed.

A branch claw 8 is used to transport the paper to the lower transport path 4.
When the sheet that has passed through the straight conveyance path 3 is detected by the sheet leading edge detection sensor 14, it waits for the time for the trailing edge of the sheet to pass through the branching portion of the lower conveyance path 4, and the conveyance roller is switched in accordance with the switching of the branching claw 8. The rear 12 is reversed and switched back and guided to the lower transport path 4.

The features of the present embodiment will be described as follows with the above configuration as an object.
One of the features of this embodiment is that the sliding resistance is reduced by reducing the frictional resistance between the paper and the staple tray when introducing the paper into the staple tray by tapping rollers. There is to make it.
FIG. 2 is a diagram illustrating an example for exhibiting the above characteristics.
In the figure, a conveyance assisting member 91 is disposed at a position facing the hitting roller 41 across the paper in the staple tray 21.

The hitting roller 41 is made of rubber, sponge, or the like, and a member having a relatively high coefficient of friction between the paper and the paper is used in order to securely grip and move the paper.
When it is assumed that the friction coefficient between the sheets is relatively small with respect to the hitting roller 41 and the vertical drag from the hitting roller 41 is the same, the conveying force is the same as that of the hitting roller 41 and the sheet. The combination of paper and paper is relatively small.
When the paper is moved toward the trailing edge fences 24 and 25 by the tapping roller 41 on the staple tray 21, the frictional force between the staple tray 21 and the lowermost paper is more than the frictional force between the papers. If it is large, there will be a shift between sheets. For this reason, there are sheets that reach the trailing edge fence and sheets that do not exist in the sheet bundle, and the trailing edges of all the sheets in the sheet bundle cannot be aligned.
For this reason, in this embodiment, the conveyance auxiliary member 91 in which the frictional force between the staple tray 21 and the lowermost sheet is smaller than the frictional force generated between the sheets generated during the movement of the sheet is provided. It is provided so that the paper does not shift.

In the embodiment shown in FIG. 2, a conveyance auxiliary member 91 is provided in which a plate-like member made of a low friction member that can contact the lowest-order sheet placed on the staple tray 21 is used.
The conveyance assisting member 91 is made of a material in which the frictional force generated between the staple tray 21 and the paper is smaller than the frictional force generated between the papers. Specifically, the following material is used. Yes. That is, a metal material such as a resin having low sliding resistance such as polyacetal, polyamide, polytetrafluoroethylene, or the like with good sliding property, an electrogalvanized steel sheet, or a steel sheet coated with polytetrafluoroethylene is used. .
Further, the present invention is not limited to the above-described materials, and a configuration in which the plate material is subjected to bead processing to reduce the contact area with the paper to reduce the sliding resistance can be used.

In the above configuration, for the paper positioned at the lowest position on the staple tray 21, the transport resistance generated between the staple tray 21 and the transport resistance generated between the sheets is reduced.
In other words, the frictional force obtained from the vertical drag and the friction coefficient between the staple tray and the lowermost sheet with respect to the frictional force obtained from the vertical drag received from the hitting roller 41 and the friction coefficient between the sheets. Is small and sliding resistance is weak. As a result, the lowermost sheet positioned on the staple tray side is more easily moved toward the rear end fences 24 and 25 than the upper stacked sheets.
Accordingly, since each of the sheet bundles on the staple tray 21 can move toward the rear end fences 254 and 25, even when the inclination of the staple tray 21 is small or the front end of the sheet cannot be pushed toward the rear end fence. , It becomes possible to align the rear ends.

Next, another embodiment relating to the features of this embodiment will be described.
In the configuration shown in FIG. 3, a driven roller 42 disposed at the same position as the configuration shown in FIG. 2 is used as a conveyance auxiliary member.
Since the driven roller 42 can be moved along with the movement of the sheet, it is possible to obtain a state in which the frictional force is small between the lowermost sheet and the staple tray 21.
In this configuration, when the sheet moves using the frictional force generated by the friction coefficient between the vertical drag painters by the tapping roller 41, the lowermost sheet is linked with the movement of the upper sheet. It can move toward the end fences 24, 25. As a result, the rear end of the sheet is abutted against the rear end fences 24 and 25 and the rear ends are aligned.

As the configuration of the driven roller 42, a configuration equipped with a one-way clutch can be used.
In this configuration, the rotation direction is set so that the sheet can be rotated only in the direction in which the sheet is conveyed toward the rear end fences 24 and 25.
Thus, it is possible to prevent the sheet from being rebounded in the reverse direction due to repulsion when the trailing edge of the sheet hits the trailing edge fences 24 and 25 and to maintain the sheet bundle in which the trailing edge is aligned.
Further, the driven roller 42 can be driven to rotate instead of the one-way clutch. The drive in this case is preferably a sponge that can move the paper toward the rear end fences 24 and 25 and that can move the paper with the material.
By using a sponge, the frictional force against the paper can be kept small, and some slip can occur between the paper and the paper can be returned too much or the damage to the printing surface can be prevented by using flexibility. .

Next, a modified example of the configuration using the driven roller will be described.
In FIG. 4, the driven roller 42 is provided so as to be able to come into contact with and separate from the paper on the staple tray 21 side. A configuration that can be rotationally driven in the moving direction is shown. The driven roller 42 is supported by a swing lever (not shown) so as to be able to contact and separate from the paper.
In this configuration, the sheet is brought into contact with the sheet when the sheet is conveyed by the hitting roller 41 and is rotated in a direction in which the sheet is moved toward the rear end fences 24 and 25. The amount of rotation at the time of rotation corresponds to the amount of movement by which the rear end of the sheet can hit the rear end fences 24 and 25. As a result, the lowermost sheet can be moved toward the rear end fences 24 and 25 by the contact of the driven roller 42 when the upper sheet is moved by the hitting roller 41.
In this configuration, since the amount of rotation necessary to move toward the rear end fences 24 and 25 is given to the driven roller 42, it is possible to prevent the paper from returning too much and causing damage to the printing surface. Become.
Note that the configuration in which the driven roller 42 is brought into contact with and separated from the sheet is not limited to using a swing member, and a solenoid or a cam drive may be used.

  In the above configuration, the upper sheet is obtained from the tapping roller 41 by making the frictional force between the lowest sheet in the sheet bundle and the staple tray 21 smaller than the frictional force between the sheets. It can be interlocked to move with frictional force. As a result, all the sheets of the sheet bundle can be brought into contact with the trailing edge fences 24 and 25, so that the trailing edge of the sheet can be aligned even when the weight of the sheet is insufficiently dropped or the sheet cannot be pushed and moved. .

Next, another feature of the example of the post-processing apparatus according to this embodiment will be described with reference to FIG.
Another feature of the present embodiment is that the sheet sandwiched between the sheets conveyed to the staple tray in the double feed state is reliably abutted against the rear end fence.
In the post-processing apparatus according to the present embodiment, for example, when three sheets are collectively conveyed to the staple tray, the first and second sheets are pressed using the lower conveyance path 4 shown in FIG. After tucking, a form is used in which the third sheet is conveyed to the staple tray 21 together with the third sheet. Accordingly, in this case, the lower transport path 4 is used as a prestack transport path.

As described above, when the sheets are aligned at the trailing edge in the staple tray 21 in a state where the three sheets are stacked, the central sheet sandwiched between the sheets may be difficult to move toward the position of the trailing edge alignment.
In other words, when the three sheets are moved in the staple tray 21 with their movement direction ends aligned, the movement of the sheet located in the center is insufficient, and the trailing edges of all the sheets cannot be aligned. Therefore, the present embodiment aims to prevent such rear end alignment from becoming insufficient.

Here, the reason why the rear end alignment of the sheet located at the center becomes insufficient is that the uppermost sheet is the tapping roller 41, and the lowermost sheet is the conveyance assisting member 42 having the configuration shown in FIG. The case where they abut each other will be described as follows.
Of the three stacked sheets, the uppermost sheet is obtained by the frictional force due to the vertical drag from the tapping roller 41, and the lowermost sheet is obtained by the frictional force due to the vertical drag from the conveyance assisting member 42. It is done.
However, the sheet located at the center has a conveying force that is a frictional force due to a coefficient of friction between sheets smaller than the frictional force acting on the uppermost and lowermost sheets. For this reason, in the central sheet, the conveying force when moving on the staple tray toward the rear end fence with the ends aligned is weaker than other sheets. As a result, the paper that moves while abutting against the tapping roller and the conveyance auxiliary member can easily make contact with the trailing edge fence, so that the trailing edge can be aligned, but the central sheet has insufficient conveying force to the trailing edge fence. There is a possibility that rear end alignment is not performed.

In the present embodiment, the transport mode is controlled by the control unit 200 shown in FIG.
In FIG. 5, the control unit 200 is a part that controls the conveyance of the sheet starting with the raising and lowering control of the discharge tray 5.
The sheet detection sensors 13 and 14 are connected to the input side of the control unit 200, and the drive units of the branching claws 7 and 8, the rear of the conveyance rollers 12, and the drive unit of the saddle stitch conveyance roller 62 are connected to the output side. . For convenience, in FIG. 5, the names of the respective members are shown in the respective drive units. In the control unit 200, when the passage of the sheet is detected, the setting of the sheet conveyance direction by switching the direction of the branch claw and the rollers used for conveyance are used. Set the rotation direction.
The roller to be used for conveyance in this case corresponds to the binding conveyance roller 62 provided in the lower conveyance path 4 used for the pre-stack conveyance path 12 after the conveyance roller and temporarily waiting for the paper. .

A control procedure in the control unit 200 will be described with reference to FIGS.
FIG. 6 shows a state where the first sheet P1 is introduced, and the configuration shown in FIG. 6 uses the sponge roller 42 as the conveyance auxiliary member shown in FIG.
In FIG. 6, when the leading edge of the first sheet P is detected by the sheet detection sensor 14, the control unit 200 sets the rotation amount after the conveying roller 12 from that point of time, and then stops. Next, as shown in FIG. 7, the direction of the branching claw 8 is switched in a direction in which the sheet can be introduced toward the lower conveyance path 4.
When the switching of the direction of the branching claw 8 is completed, the control unit 200 rotates the saddle stitch conveyance roller 62 after the conveyance roller 12 in the direction opposite to the rotation direction so far, as shown in FIG. The paper P1 is introduced into the lower conveyance path 4 by the guide of the branching claw 8.
The control unit 200 sets the rotation amount of the first sheet P1 introduced into the lower transport path 4 from the start of the rotation of the rear 12 of the transport rollers. The rotation amount is a rotation amount with which the rear end in the conveyance direction of the paper P1 along the direction in which the first sheet P1 is introduced into the lower conveyance path 4 is opposed to the nip portion 12 after the conveyance roller. ing.

When the second sheet P2 is introduced into the post-processing apparatus in a state where the rear end of the first sheet P1 is sandwiched by the rear 12 of the conveying roller, the branching claw 8 is 1 as shown in FIG. The direction is switched in the same direction as when the first sheet P1 is introduced.
After the transport roller 12, the saddle stitch transport roller 62 resumes rotation at a stage before the second sheet P2 reaches the post-transport roller 12. That is, the first sheet P1 is resumed at a time before the second sheet P2 starts to be nipped and transported 12 after the transport roller, and reaches the transport path where the second sheet P2 arrives. It is fed out from the downward conveying path 4. As a result, as shown in FIG. 10, the first sheet P1 moves in advance by the distance that the second sheet P2 starts moving earlier than the time when the second sheet P2 is fed out by the transport roller 12. .
The preceding amount of the first sheet P1 corresponds to an amount capable of maintaining the state where the first sheet is held between the conveyance rollers 12 when the leading edge of the second sheet P2 passes through the branching claw 8. I'm allowed.

The control unit 200 calculates the time until the conveyance roller 12 after the output of the signal from the sheet detection sensor 13 capable of detecting the passage of the second sheet P2, and the second sheet P2 is conveyed by the conveyance roller. The time before reaching the back 12 is set as the conveyance resumption time of the first sheet P1.
As a result, when the second sheet P2 is introduced, nipped and conveyed by the rear 12 of the conveying rollers, and stopped, the end of the first sheet P1 becomes the end of the second sheet P2, as shown in FIG. The part sandwiched by the paper discharge roller 26 and the driven roller 27 protrudes outside the machine.

As shown in FIG. 11, the two sheets P1 and P2, which are sandwiched and stopped by the rear 12 of the conveying roller, are lowered as in the case of introduction to the lower conveying path 4 for the first sheet P1. It is introduced toward the conveyance path 4. At this time, the rear 12 of the conveying roller turns in the reverse direction, and the saddle stitch conveying roller 62 rotates in the direction following this direction.
When the sheets P1 and P2 are introduced into the lower conveyance path 4, the control unit 200 moves the branching claw 8 at the time when the rear ends of the sheets P1 and P2 pass the conveyance roller 12 and the third sheet P3. Is switched to a state of moving toward the rear 12 of the conveying rollers.

  The sheets P1 and P2 introduced into the lower conveyance path 4 are fed by the saddle stitch conveyance roller 62 in which the third sheet P3 is introduced and the rotation direction is switched to the sheet feeding direction according to the retention time. As shown in FIG. 12, it merges with the third sheet P3.

Among the merged sheets P1 to P3, the sheet P2 located at the center has the sheet discharge roller 26 and the driven member with the end portion shifted between the first and second sheets as shown in FIG. The sheet is held by the roller 27 and stopped in a state where a part of the sheet is protruded from the apparatus together with other sheets.
As shown in FIG. 13, the central position where the end located on the rear end fence 24, 25 side precedes the end of the other sheets by the setting of the conveyance form of the first sheet and the second sheet. The paper P <b> 2 is conveyed toward the staple tray 21 by the paper discharge roller 26 and the driven roller 27.
When transporting the sheets P1 to P3 toward the staple tray 21, the tapping roller 41 and the transport auxiliary member 42 are also rotationally driven.
As a result, the sheet P2 whose end on the rear end fence 24, 25 side precedes the uppermost sheet P3 is first hit and receives the vertical drag of the roller 41 and moves to the rear end fence 24, 25 side.
As shown in FIG. 14, the sheet P2 located in the middle at this time precedes and follows the other sheets by utilizing the fact that the frictional force generated by the tapping roller 41 is larger than the frictional force generated between the sheets. It moves toward the end fences 24, 25 and hits the end.

On the other hand, the sheets that move on the staple tray 21 are linked using the inter-sheet friction in accordance with the movement of the sheet P2, but the uppermost sheet P3 receives the frictional force of the tapping roller 41 and the lowermost sheet P3. The sheet P1 moves under the frictional force of the conveyance assisting member.
For this reason, even if the sheet P2 located at the center hits the rear end fences 24 and 25 prior to the other sheets, the rear ends of the rear end fences 24 and 25 are caused by the frictional force between the members. Can be faced. As a result, the rear end fences 24 and 25 are applied to the rear end fences 24 and 25 by the frictional force from the tapping roller 41 and the frictional force from the conveyance assisting member 42, which are larger than the frictional force between the central sheet P2 and the central sheet P2 that is in contact with the rear end fences 24 and 25. The rear end can be abutted.
As a result, as shown in FIGS. 15 and 16, the rear ends of the three sheets abut against the rear end fences 24 and 25, thereby aligning the rear ends.

In the above configuration, by shifting the edge of the central sheet that may move only by the inter-sheet friction that provides a smaller frictional force than the frictional force of the tapping roller 41 or the conveyance assisting member 42, and the other sheet. The trailing edge can be aligned by receiving the driving force of the tapping roller that is larger than the inter-paper friction.
As a result, even when the inclination of the staple tray 21 is small or the edge of the sheet cannot be pushed and moved, all the sheets to be fed can be brought into contact with the trailing edge fence, so that the trailing edge can be aligned. Become.

DESCRIPTION OF SYMBOLS 1 Post-processing apparatus 4 Lower conveyance path 8 Branching claw 12 After conveyance roller 21 Staple trays 24, 25 Rear end fence 41 Tapping roller 42 Roll as a conveyance auxiliary member 62 Saddle stitch conveyance roller 91 Conveyance member 100 Image forming system 200 Control unit G Image forming apparatus P1 to P3 Paper

Japanese Patent Laid-Open No. 07-165365 JP 2008-001479 A

Claims (8)

A transport path for transporting paper toward a staple tray provided opposite to the binding means used for paper binding processing, a pre-stack transport path for branching from the transport path to temporarily wait for paper, and the staple tray An edge fence that is provided and abuts the edge of the sheet to align the edge, and a return roller that is disposed above the staple tray in the vicinity of the edge fence and moves the sheet toward the edge fence A post-processing apparatus comprising:
Post-processing is characterized in that a conveyance auxiliary member smaller than a frictional force between sheets generated when the sheet is moved by the return roller is provided at a position facing the return roller across the sheet. apparatus.   The post-processing apparatus according to claim 1, wherein the conveyance auxiliary member is a plate-like member made of a low friction member that contacts a sheet placed on the staple tray.   A roller that can be driven to rotate is used as the conveyance assisting member, and the roller is driven by a rotation amount that allows the end of the sheet to abut against a rear end fence positioned on the staple tray. The post-processing apparatus according to claim 1.   The post-processing apparatus according to claim 1, wherein the roller used as the conveyance auxiliary member is provided so as to be able to contact and separate from the sheet.   The post-processing apparatus according to claim 2, wherein the plate-like member used as the conveyance auxiliary member is made of sponge.   The post-processing apparatus according to claim 4, wherein the roller used as the conveyance auxiliary member is made of a sponge.   When the three sheets are stacked and conveyed toward the staple tray, a conveyance mode is set in which the sheet at the position sandwiched between the sheets is preceded by other sheets and conveyed toward the rear end fence. The post-processing apparatus according to claim 1.   8. An image forming system comprising: the post-processing apparatus according to claim 1 attached to an image forming apparatus.

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