JP2014177330A - Post-processing device and image formation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a post-processing device configured to securely align end edges of sheets of paper which are fed together one over the other to each other.SOLUTION: A control part 1000 performs driving control over a conveyance member 20 so as to secure conveyance of a lower sheet of paper between sheets of paper which are fed together one over the other to an end edge fence 11 by a return roller 14 by controlling a conveyance style such that the end edge of the lower sheet of paper located on a staple tray 8 far away from the return roller 14 is at a distance, larger than the distance between the return roller 14 and end edge fence 11, from an end edge of the upper sheet of paper.

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).
In the alignment process, in addition to the case where the sheets are stacked one by one on the staple tray, there are cases where two sheets are double-fed and simultaneously discharged onto the staple tray.

When transporting two sheets of paper at the same time, using the above-described return roller and hitting roller to transport the rear end in the sheet transport direction toward the rear end fence, there are the following problems.
That is, both the return roller and the hitting roller are in contact with the upper surface of the paper and transport the paper in the direction opposite to the transport direction. For this reason, when the coefficient of friction between the lower sheet and the conveying member in contact with the lower sheet is higher than the coefficient of friction between the sheets, or because the area of the image carried between the upper and lower sheets differs easily For example, the lower sheet may not be transported.
When the sheets are slid down toward the rear end fence by gravity, the inclination angle of the tray on which the sheets are stacked becomes a problem. In other words, when the inclination angle is small, the lower sheet cannot move if the friction coefficient between the sheet and the tray is large, and as a result, even if a return roller or a hitting roller is used, The trailing edge cannot be aligned.

  Therefore, as a transport format in which the lower paper is positively moved, the leading edge position of the lower paper and the upper paper is shifted so that each paper is transported to the rear end fence. Has been proposed (for example, Patent Document 2).

In the configuration disclosed in Patent Document 2, the leading edges of the sheets to be fed are shifted while being discharged to the tray, and after the sheets are discharged to the tray, they are preceded by the upper and lower individual sheets. The trailing edge can be aligned by conveying the sheet on the tray with a member that contacts the upper surface of the sheet.
On the other hand, in the configuration disclosed in Patent Document 2, it is assumed that there is friction between sheets. For this reason, for example, in a solid color copy in which a lot of toner is placed on the paper, the friction between sheets is considerably reduced.
Furthermore, when the inclination of the tray is small, it is likely to be affected by the frictional force generated between the lower sheet and the surface of the tray. For this reason, the lower sheet cannot receive a force indirectly exceeding the frictional force between the sheet and the tray only by the conveyance force acting directly on the upper sheet. As a result, the lower sheet is not conveyed to the trailing edge fence, and the sheets are not aligned in the sheet conveying direction.
Further, the disclosure in Patent Document 2 is based on the premise that there is no configuration corresponding to the return roller and that the tray is inclined to some extent. For this reason, there is a problem that the sheets cannot be properly aligned when the assumed length in the transport direction of the paper is larger than the length of the staple tray in the transport direction or when the inclination of the staple tray is small.

  An object of the present invention is to provide a post-processing apparatus and an image forming system having a configuration capable of surely aligning edges of sheets when double-fed in view of the problems in the conventional post-processing apparatus. .

  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 tapping roller and a return roller that are moved toward the edge fence, a discharge unit that includes a discharge claw that discharges the paper on the staple tray after the binding process, and a conveyance path toward the conveyance path and the prestack tray. A post-processing apparatus having a conveying member and a driving source for the discharging means, and disposed at a paper inlet in the conveying path to detect passage of the paper An entrance sensor, a paper presence / absence detection sensor which is disposed near the edge fence of the staple tray and detects the presence / absence of paper is connected to the input side; A control unit to which a driving source of the means is connected, and the return roller is disposed closer to the edge fence than the hitting roller, and the distance from the edge fence is L2. When the two sheets are double-fed, the control unit waits for the first sheet on the prestack tray, and after the second sheet passes through the conveyance path, When the second sheet is fed out from the prestack tray and conveyed along the conveyance path along with the second sheet toward the staple tray, the lower end of the sheet in the conveyance direction is positioned on the upper side. The lower sheet is first carried into the staple tray by shifting by a distance L1 that satisfies L2 ≦ L1 with respect to the distance L2 between the edge fence and the return roller with respect to the position of the rear end of the sheet to be conveyed. In the post-processing apparatus, the driving state of the driving source is set as described above.

  According to the present invention, the two sheets carried into the staple tray can be preceded by the lower sheet by shifting the position of the rear end in the transport direction between the first sheet and the second sheet. Moreover, the sheet can be moved toward the edge fence in advance by the difference between the distance between the edge fence and the return roller and the shifted distance, and then the second sheet is returned to the return roller and the return roller. It is moved toward the edge fence by hitting rollers. As a result, the sheet located on the lower side is abutted against the edge fence regardless of the frictional relationship with the tray or the difference in sliding property due to the difference in image area between the sheets, and the edges can be aligned.

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 figure for demonstrating the malfunction when two sheets of paper are double-fed. FIG. 2 is a diagram for explaining an example of a sheet conveyance process in the post-processing apparatus illustrated in FIG. 1. It is a figure for demonstrating the state which passed from the conveyance process shown in FIG. It is a figure for demonstrating the edge alignment mechanism of the paper used for the post-processing apparatus shown in FIG. It is a block diagram for demonstrating the structure of the control part used for the post-processing apparatus shown in FIG. It is a flowchart for demonstrating the effect | action of the control part shown in FIG. It is a figure for demonstrating another Example of the post-processing apparatus which concerns on this embodiment. It is a flowchart for demonstrating the effect | action of the control part made into the object of the structure of FIG. It is a figure for demonstrating the principal part modification of the structure shown in FIG. It is a flowchart for demonstrating the effect | action of the control part aiming at the structure of FIG. It is a figure for demonstrating the other Example of the post-processing apparatus which concerns on this embodiment. It is a flowchart for demonstrating the effect | action of the control part aiming at the structure of FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to illustrated embodiments.
FIG. 1 is a diagram illustrating a configuration of a post-processing apparatus according to an embodiment of the present invention and an image forming system using the same.
In FIG. 1, the image forming system 100 has a configuration in which a post-processing device 1 described below is arranged continuously to a sheet discharge portion of the fixing device G1 in the image forming device G.

The post-processing apparatus 1 includes a second conveyance path 3 and a third conveyance path 4 that are branched in the middle of the first conveyance path 2 that conveys the image-formed paper discharged from the image forming apparatus G.
The second conveyance path 3 is continuous to the proof tray 3A, and the third conveyance path 4 is continuous to the binding means 5 that performs post-processing such as sheet shift processing, binding processing, and two-point binding processing. .
The third transport path 4 is a prestack transport path for transporting paper toward a prestack tray (not shown).
The pre-stack tray is a tray used for temporarily waiting the paper branched from the first conveyance path and feeding it again.
At the branch position of the first conveyance path 2, a rotatable first that can be switched from the first conveyance path 2 to the third conveyance path 4 with the sheet conveyance direction directed toward the first conveyance path 3. A branch claw 6 and a second branch claw 7 are respectively arranged.
In the first conveyance path 2, a portion for conveying the sheet toward the staple tray 8 in the binding unit 5 is extended at a position where the sheet passes through each branch position.

The first transport path 2 is provided with an inlet roller 2A on the paper inlet side of the punching unit 9 and an inlet sensor S1 that is disposed at the paper inlet and detects the passage of the paper.
Further, a front conveying roller 10A is disposed on the upstream side in the conveying direction across the branch position in the first conveying path 2, and a rear conveying roller 10B is disposed on the downstream side in the conveying direction, and a sheet is disposed in the vicinity of the rear conveying roller 10B. A rear passage sensor S2 for detecting the passage of is disposed.

The binding means 5 is provided with an edge fence 11 provided on the staple tray 8 for aligning the edges by abutting the edge of the paper, and an end binding stapler 12 disposed in the vicinity of the edge fence 11. Yes.
The staple tray 8 is provided with a hitting roller 13 and a return roller 14 that are disposed above and move the sheet toward the edge fence 11.
Further, the binding means includes a discharge means 15 below the staple tray 8 and a jogger fence 16 that aligns the side edges facing the side edges of the paper.
The discharge means 15 is provided on a part of the discharge belt 15A and a part of the discharge belt 15A, which is located below the staple tray 8 and has a stretched surface along the sheet conveyance direction on the tray 8, and has an edge of the sheet. A release claw 15B that pushes and releases is provided.
The staple tray 8 is provided with a sheet presence / absence detection sensor S3 that is disposed in the vicinity of the edge fence of the staple tray 8 and detects the presence / absence of the sheet.

  A paper discharge roller 17 and a driven roller 18 are disposed on the side opposite to the end binding stapler 12 in the staple tray 8, and a paper discharge tray 19 is provided on the casing wall of the post-processing apparatus 1 in the vicinity of these rollers. Has been. In FIG. 1, reference numeral 20 indicates a transport roller provided in the third transport path 4 toward the prestack tray.

In the post-processing apparatus 1 having the above configuration, a conveyance path is selected according to a conveyance mode for a sheet.
That is, the paper that is discharged from the image forming apparatus G and does not require post-processing such as binding processing is guided to the second conveyance path 3 by the rotation position of the first branching claw 6.
Sheets that require post-processing such as binding processing are those after passing the branch position of the first transport path 2 from the entrance side of the first transport path 2 depending on the rotational positions of the first branch claw 6 and the second branch claw 7. The paper is conveyed toward the extension and sequentially stacked on the staple tray 8.
A bundle of sheets stacked on the staple tray 8 is moved toward the edge fence 11 with the tapping roller 13 and the return roller 14 coming into contact with each other, thereby aligning the edges, and the displacement of the jogger fence 16. By operation, the side edges are aligned.
When a predetermined number of sheets are bound by the stapler 12, the stapler 12 moves in the sheet width direction and performs the binding process at a predetermined position.

By the way, while a predetermined number of sheets are being bound, the sheet discharged from the image forming apparatus G cannot be conveyed toward the staple tray 8.
For this reason, when the succeeding sheet is sandwiched between the rear conveyance rollers 10 positioned in the extended portion of the first conveyance path 2, the conveyance direction up to that time is changed toward the third conveyance path 4. Can be switched.
That is, when the rear end of the sheet in the conveyance direction reaches the branch position with respect to the third conveyance path 4, the rear conveyance roller 10 is reversed and conveyed toward the third conveyance path 4.

The sheet sandwiched between the transport rollers 20 located in the third transport path 4 stops in a state of being sandwiched by the rotation of the transport rollers 20, and is once in a standby state in the third transport path 4.
The bundle of sheets for which the binding process has been completed is conveyed from the staple tray 8 toward the paper discharge tray 19 by the discharge unit 15.
When the sheet bundle that has finished the binding process is discharged, the sheet that has been waiting in the third transport path 4 is fed out again. At this time, a part of the sheet fed out from the third conveyance path 4 faces the rear conveyance roller 10B of the first conveyance path 2, so that the sheet discharged from the image forming apparatus G and the first conveyance path 2 together. Multi-feed toward the staple tray 8.

The reason why edge alignment cannot be performed when two sheets of paper are double-fed as described above will be described next. In FIG. 2, an alternate long and short dash line arrow indicates the movement of the sheet located on the lower side, and a solid line arrow indicates the movement of the sheet located on the upper side.
In FIG. 2, there is a state in which the sheet conveyed from the prestack of the third conveyance path 4 toward the first conveyance path 2 is conveyed with a delay with respect to the sheet conveyed from the image forming apparatus G toward the first conveyance path 2. It is shown in (A).
In such a transport mode, among the sheets discharged to the staple tray 8, the lower sheet (indicated by the alternate long and short dash line) is more offset toward the edge fence 11 than the upper sheet (indicated by the solid line). It is transported in a shifted state.

The double fed paper is conveyed toward the edge fence 11 when the return roller 14 rotates in the direction indicated by the arrow, but the edge of the double fed paper cannot be aligned under the following conditions.
That is, when the inclination of the staple tray 8 is increased in order to promote the sliding of the sheet or when the friction coefficient between the lower sheet and the staple tray is small, the upper sheet is moved by the rotation of the return roller 14. At the same time, the lower sheet moves and hits the edge fence.
However, when the inclination of the staple tray 8 is small or the friction coefficient between the lower sheet and the staple tray 8 is large, the upper sheet reaches the position of the return roller 14 as shown in FIG. Then, the state shown in FIG.
That is, as shown in (C), only the upper sheet is conveyed toward the edge fence 11 by the return roller 14 due to the rotation of the return roller 14, and the lower sheet tends to stay on the staple tray.
As a result, only the upper edge of the sheet abuts against the edge fence 11, and the edges of the sheets positioned on the upper side cannot be aligned.

In the present embodiment, the upper and lower sheets with respect to the edge fence, in particular, the lower sheet that is less susceptible to the conveying force of the return roller 14 when the upper sheet comes into contact with the return roller 14, A conveyance mode is set so as to face the return roller 14 until the edge fence 11 is reached.
Hereinafter, the principle of this transport mode will be described.
3 and 4 are provided on the first and second transport paths 2 and 4 and the front transport roller 10A, the rear transport roller 10B, and the staple tray 8 used as transport rollers disposed in each of the transport paths. The arrangement | positioning relationship of the return roller 14 and the edge fence 11 is shown.
FIG. 3A shows a state in which subsequent sheets cannot be conveyed toward the staple tray 8 during the binding process of the preceding sheet bundle.
In the same figure, the following paper (shown by the alternate long and short dash line) is nipped and conveyed by the rear conveyance roller 10B, and conveyed toward the third conveyance path 4 when the conveyance direction rear end passes through the second branch claw 7. At this time, the sheet is conveyed toward the third conveyance path 4 by the rotation of the second branch claw 7 and the reverse rotation of the rear conveyance roller 10B, and is temporarily put on standby by the press tacker.

When the sheet bundle is discharged from the staple tray 8 after the binding process is completed, the sheet (shown by a solid line) discharged from the image forming apparatus G is transported into the first transport path 2.
At this time, the sheet discharged from the image forming apparatus G overlaps a part of the sheet (indicated by the alternate long and short dash line) that has been waiting on the third conveyance path 4. FIG. 3B shows this state.

When the paper that has been waiting in the press tacker is fed out again and transported in a state of being overlapped with the paper in the first transport path 2, the third transport path is the distance indicated by reference numeral L <b> 1 in FIG. The feeding timing when feeding from 4 is shifted.
On the other hand, the distance between the edge fence 11 provided in the binding means 5 and the return roller 14 is positioned at a distance indicated by reference numeral L2, and the distance L2 is relative to the deviation L1 between the edges of the sheets. , L2 ≦ L1 is set.

The sheet transported to the staple tray 8 in a stacked state is a distance between the edge of the sheet (shown by a one-dot chain line) positioned on the lower side on the staple tray 8 and the edge of the sheet positioned on the upper side. It precedes L1 and hits the edge fence 11 in a state shifted from the upper sheet.
At this time, based on the distance relationship L2 ≦ L1, the upper sheet does not face the return roller 14 until just before the lower sheet hits the edge fence (period corresponding to L1-L2). The edge of the sheet on the side is conveyed toward the edge fence.
Immediately before the lower sheet hits the edge fence, the upper sheet faces the return roller 14, so that the upper sheet is also conveyed to the edge fence by the return roller 14.

Due to the principle of the transport mode as described above, among the multi-fed sheets, the lower sheet at a position far from the return roller 14 is moved by the return roller 14 before the upper sheet at a position close to the return roller 14. It can be transported toward the edge fence 11.
As a result, the edge of the upper sheet abuts on the edge fence following the lower sheet, so that the edges of the double-fed sheets are reliably aligned.

In particular, when the position of the edge of the upper and lower sheets is shifted, the inclination (inclination angle) of the staple tray 8 is increased and the relationship of the friction coefficient between the tray and the lower sheet is decreased. It is only necessary to specify the amount of deviation between the edges without having to set the conditions.
As a result, it is possible to align the edges of the sheets to be double fed without changing the structure of the staple tray.

Next, another example of edge alignment for the configuration shown in FIGS.
FIG. 5 shows a procedure for causing the hitting roller 13 to contribute to the edge alignment in addition to the staple tray 8, the edge fence 11, and the return roller 14 shown in FIG.
In FIG. 5A, among the two sheets discharged to the staple tray 8, the lower sheet is first sandwiched between the return roller 14 and the staple tray 8.
When the return roller 14 is rotated in the direction of the arrow in this state, the sheet is conveyed to the edge fence 11. As the lower sheet is conveyed, the upper sheet is conveyed together to the edge fence 11 side.

At this time, when the lower sheet reaches the edge fence 11 by giving the distance relationship described in FIGS. 3 and 4, that is, the shift amount between the edges of the sheets, the upper sheet is different in distance ( The edge is located at a position corresponding to (L1-L2).
As shown in FIG. 5B, the upper sheet whose edge is shifted with respect to the lower sheet is insufficiently slid on the staple tray 8, as shown in FIG. 14 may not be able to be transported without being opposed to 14.
Therefore, as shown in FIG. 5C, the upper sheet can be conveyed to the position of the return roller 14 using the hitting roller 13.
The hitting roller 13 is rotated in the direction of the arrow shown in the drawing to rotate in a direction in which the paper is moved toward the edge fence 11, so that when the upper roller touches the upper paper, the paper can be moved toward the return roller 14. it can.
The upper sheet that has reached the position of the return roller 14 is thereafter conveyed toward the edge fence 11 by the return roller 14 as shown in FIG.

Here, the distance relationship described above will be described.
When the distance relationship corresponding to the deviation amount of the edges of the sheets is a relationship opposite to the relationship of L2 ≦ L1 (L2> L1), the lower sheet is being conveyed by the return roller 14 in the middle. Only the upper sheet contacts the return roller 14. For this reason, there is a possibility that only the upper sheet in contact with the return roller 14 is conveyed. When such a phenomenon occurs, it becomes impossible to align the edges of the sheets where the lower sheet does not reach the edge fence.

The above transport mode is controlled by the control unit 1000 shown in FIG.
In FIG. 6, a control unit 1000 is a control unit capable of transmitting and receiving with the control unit of the image forming apparatus G, and an operation panel 1001, an entrance sensor S1, a rear passage sensor S2, and a sheet presence / absence detection sensor S3 are connected to the input side. Yes.
The operation panel 1001 is provided on the image forming apparatus G side, and inputs the presence / absence selection of the post-processing mode, the number of sheets used for the sheet bundle, and the like.
On the output side of the control unit 1000, the driving of a discharge belt 15A used in the discharge means 15 provided with a drive roller drive motor used as each transfer member and a discharge claw 15B that discharges the paper on the staple tray 8 after the binding process is performed. A drive motor for the discharge belt which is a source is connected.

When the post-processing mode is selected, the control unit 1000 waits in the press tacker for the first sheet used when the next job is executed while the number of sheets used for the sheet bundle is discharged to the staple tray 8. The conveyance form to the 3rd conveyance path 4 is set so that it may carry out.
The sheets waiting in the third conveyance path 4 are fed out from the third conveyance path 4 and overlapped with each other as the subsequent second sheet in the next job is conveyed to the first conveyance path 2. In this state, it is conveyed toward the staple tray 8. The state at this time is as shown in FIG. 3 and FIG.

On the other hand, the control unit 1000 controls the driving start timing of the transport roller so that the positions of the edges of the sheets can be shifted when the sheets are transported in an overlapped state. The drive start timing of the transport roller is targeted at the drive start timing which is one of the drive positions at the drive source of the transport roller.
That is, when the first conveyance path is conveyed in a stacked state, as shown in FIG. 4, the lower edge of the sheet discharged to the staple tray 8 is the upper edge of the sheet. The position is shifted with respect to the position. For this reason, the control unit 1000 controls the conveyance start timing of the sheet fed out from the third conveyance path 4 corresponding to the lower sheet. For this control, the conveyance roller 20 located in the third conveyance path 4 is used, and the drive start timing of the conveyance roller 20 is delayed by a timing corresponding to the deviation amount.

For the transport mode as described above, the control unit 1000 uses a procedure according to the flowchart of FIG.
In the control unit 100, the presence / absence determination of the binding processing mode from the operation panel 1001 is executed (ST1).
In this determination, in the post-processing mode, that is, the post-processing mode such as the binding process or the sheet bundle shifting process, the transport mode toward the proof tray 3A is set in the following case (ST3). That is, when the binding process is not performed, when the shift process is not performed, or when the post-processing is not necessary after the punching process, the conveyance mode toward the proof tray 3A is set.

If the post-processing mode is selected in step ST1, the presence / absence of a sheet on the staple tray 8 is determined (ST3). If it is determined that no sheet is loaded, the first sheet is The paper is discharged onto the staple tray as it is.
The subsequent second and subsequent sheets are also discharged in order on the first sheet discharged onto the staple tray as it is. After all sheets are discharged onto the staple tray, stapling is performed, and the sheet bundle is discharged onto the discharge tray.

Whether or not the preceding sheet for the next job, that is, the first sheet (the sheet indicated by the alternate long and short dash line in FIGS. 3 and 4) is introduced in the state where sheets are present on the staple tray 8 in step ST3. Discriminated (ST4).
When the first sheet in the next job is introduced in step ST5, as described in FIGS. 3 and 4, a process of waiting the first sheet in the third transport path 4 is executed.
That is, when the trailing edge of the first sheet is detected by the rear passage sensor S2 (ST5), the rear conveyance path roller 10B is changed from the normal rotation state during conveyance to the reverse rotation, and at the same time, the third conveyance path 4 The inner conveyance roller 20 is driven to introduce the first sheet into the third conveyance path 4 (ST6).
The first sheet introduced into the third conveyance path 4 is maintained in the primary standby state by the press tacker, but not all of the length in the conveyance direction is introduced into the third conveyance path 4. As shown in FIG. 3, the apparatus waits in a state where a part remains in the first transport path 2.
In step ST5, detection by the rear passage sensor is used as a trigger, but switchback is possible if the rear end of the paper passes through the second branching claw. For example, the timer counting may be started after the trailing edge of the sheet has passed the entrance sensor S1, and the time when the trailing edge of the sheet is expected to pass the second branching claw may be used as a trigger for reversing the rear conveyance roller.

When the preceding first sheet is waiting in the third conveyance path 4, it is determined whether the succeeding second sheet (the sheet indicated by the solid line in FIGS. 3 and 4) has been introduced in the next job. Discriminated (ST7).
When the second sheet is transported through the first transport path 2, the second sheet is introduced and at the same time, the preceding first sheet is fed out from the third transport path 4. Thus, in the first transport path 2, as shown in FIG. 4, the first and second sheets are transported toward the staple tray 8 in a state where the first and second sheets overlap each other.

At this time, the control unit 1000 provides a shift (L1) between the edges of the first sheet and the second sheet, and this shift causes a distance (L2) between the return roller 14 and the edge fence 11. ) To set the drive timing of the transport roller 20 in the third transport path 4 (ST8). In this process, the feed start timing by the transport roller 20 located in the third transport path 4 is delayed.
The above procedure is continued until the specified number of sheets is reached (ST9). Note that when sheets overlap each other, not all sheets used for the sheet bundle are targeted, but the first and second sheets in the succeeding job are targeted when the preceding job is being executed.
For this reason, the process of step ST10 is a process of determining that the first and second sheets are abutted against the edge fence of the staple tray 8.

In the above configuration, the lower sheet on the staple tray 8 close to the return roller 14 is transported by the return roller 14 toward the edge fence in advance of the upper sheet farther than the return roller 14. Is done. As a result, even when the inclination angle of the staple tray 8 is small, the return roller 14 can be reliably conveyed while facing the lower sheet.
Further, the tapping roller 13 rotates in the direction of the arrow shown in FIG. 5 and rotates in a direction in which the sheet moves toward the edge fence 11, so that when the upper roller contacts the upper sheet, the sheet is directed toward the return roller 14. Can be moved.
After that, the upper sheet that has reached the position of the return roller 14 is conveyed toward the edge fence 11 by the return roller 14 as shown in FIG. Alignment is possible.

Next, another example of the post-processing apparatus according to this embodiment will be described.
The feature of another embodiment is that the facing angle of the sheet with respect to the staple tray 8 is changed by moving the discharge claw 15B used for the discharge means 15 and pushing up the sheet.
FIG. 8 is a view for explaining the operation of the release claw 15B.
In FIG. 8, (A) shows a state before the paper is pushed up by the discharge claw 15B, and (B) shows a pushed-up state.

The reason for using the action of pushing up the paper by the discharge claw 15B is as follows.
The two sheets discharged to the staple tray 8 slide toward the rear end fence along the inclination of the staple tray 8, and the lower sheet moves between the return roller 14 and the staple tray 8 as described with reference to FIG. If the sheet is nipped, the edges of the sheets can be aligned.
However, as described with reference to FIG. 2, when the inclination of the staple tray 8 is small or when the friction coefficient between the staple tray and the lower sheet is large, the sheet does not slide along the inclination of the staple tray. The paper stops at the position shown in (A).
For this reason, the lower sheet cannot be transported forward toward the edge fence 11 by the return roller 14, and the sheet cannot be aligned in the transport direction.

Therefore, in the control unit 1000 shown in FIG. 7, after the position of the paper discharged to the staple tray 8 is detected by the paper presence / absence detection sensor S <b> 2, the paper cannot be conveyed toward the edge fence 11 by the return roller 14. In this case, a control for pushing up the paper is performed.
FIG. 9 is a flowchart showing a control procedure in the control unit 1000.
In FIG. 9, when the paper is discharged to the staple tray 8 (ST20), the return roller 14 is driven to bring the paper into a state where it can be conveyed toward the edge fence 11 (ST21).
At this time, the presence / absence of the sheet is determined based on the detection signal from the sheet presence / absence detection sensor S2 (ST22), and if there is no detection signal from the sheet presence / absence detection sensor S2, it is determined that the conveyance by the return roller 14 is not performed.

When the sheet cannot be conveyed by the return roller 14, the discharge claw 15B provided on the discharge belt 15A is moved in the direction opposite to that during the sheet conveyance. (ST23)
At this time, as shown in FIG. 8B, when the discharge claw 15B is moved, the back portion, which is the upper surface of the discharge claw 15B, is brought into contact with the paper to make it easier to slide the paper.
When the paper is pushed up by the discharge claw 15B, the paper slides using gravity. The inclination angle is changed according to the presence / absence detection of the sheet by the sheet passage detection sensor S2.

  In this manner, by using the paper pushing-up operation by the discharge claw 15B, simultaneous sliding of the two sheets can be promoted, and the return roller 14 is reliably conveyed to the edge fence 11. As a result, the edges of the two sheets can be aligned.

  Incidentally, when the hitting roller 13 provided in the discharge means 15 is used, the hitting roller 13 contacts only the upper sheet, so that only the upper sheet is transported, resulting in two sheets of paper. There is a risk that the edges of each other cannot be aligned.

Next, a modification of the main part of the configuration shown in FIG. 8 will be described.
The configuration shown in FIG. 10 is characterized in that the amount of movement of the discharge claw 15B is changed for the configuration shown in FIG.
That is, in the configuration shown in FIG. 11, unlike the case shown in FIG. 8, the discharge claw 15 </ b> B is moved to the extension region of the belt 15 </ b> A to increase the facing angle of the sheet with respect to the staple tray 8.

In this case, the control unit 1000 uses the procedure shown in FIG.
In FIG. 11, after the detection signal from the sheet presence / absence detection sensor S2 in the procedure described with reference to FIG. 9 is determined (ST22), if the sheet is not detected, the discharge is performed with the movement amount greater than the movement amount shown in FIG. The claw 15B is moved in the direction opposite to that during paper conveyance (ST24 ').
As a result, the discharge claw 15B moves to the extension region of the belt 5A and pushes up the back surface of the paper, but as shown in FIG. 10C, the paper faces the staple tray 8 with the position of the return roller 14 as a fulcrum. A state where the angle can be increased is obtained.
If a sheet is detected in step ST22, the movement drive in the reverse direction in step ST24 ′ is stopped, and the discharge claw 15B is moved in the same direction as when the sheet is discharged from the position where the sheet is pushed up. Return to the discharge standby position (ST25 ').

  In this configuration, the amount of paper that is pushed up increases, so that the paper can slide well and the paper can easily move toward the edge fence. become.

In the configuration shown in FIGS. 8 and 10, a material having a high coefficient of friction such as rubber is used for the surface of the discharge claw 15 </ b> B in contact with the paper in order to push up the paper.
By using such a material having a high coefficient of friction, it is possible to favorably move the paper at the position where it is pushed up without being slipped when contacting the paper. As a result, the paper can be easily pushed up, and the paper can be easily moved toward the return roller 14.

Next, another example regarding the post-processing apparatus according to the present embodiment will be described.
The feature of the present embodiment is that the return roller 14 is provided so as to be movable along the sheet conveyance direction. FIG. 12 shows the principle configuration of the above feature.
The return roller 14 conveys the lower sheet shifted from the edge of the upper sheet on the staple tray 8 toward the edge fence 11 prior to the upper sheet. However, as shown in FIG. 12A, contact cannot be made unless the lower sheet slides down due to the inclination angle of the staple tray 8 or the like.
Therefore, in this embodiment, as shown in FIG. 12B, the return roller 14 is moved in the paper transport direction according to the detection result from the paper presence / absence detection sensor S2, and is brought into contact with the lower paper. It has become.
When the return roller 14 is moved and brought into contact with the lower sheet, the sheet is detected by the sheet presence / absence detection sensor S2.
For this reason, the control unit 1000 calculates the detection result of the sheet presence / absence detection sensor S2 and the amount of movement of the return roller 14.

FIG. 13 is a flowchart for explaining the operation of the control unit 1000 targeted for this embodiment. In each step, the same steps as those shown in FIG. 9 are denoted by the same reference numerals.
In the figure, if no paper is detected on the staple tray 8 by the paper presence / absence detection sensor S, the return roller 14 is moved in the direction away from the rear end fence 11 along the transport direction (ST25).
If there is a sheet, the sheet is conveyed by continuing only rotation without moving (ST26).
When the conveyance of the sheets by the return roller 14 is completed and the edges are aligned, the return roller 14 is returned to the original position (ST27, ST28).
The amount of movement of the return roller 14 is determined by a signal from the sheet presence / absence detection sensor S2. Specifically, the movement amount is changed until the sheet is detected by the sheet presence / absence detection sensor S2.

  In the above configuration, even in the case where the inclination angle of the staple tray 8 cannot be increased, the sheet can be reliably conveyed only by moving the return roller 14.

1 Post-processing device 2 First transport path
4 Second transport path 8 Staple tray 10B Rear transport roller 11 Edge fence 14 Return roller 15 Discharge means 15B Discharge claw 100 Image forming system 1000 Control unit 1001 Operation panel G Image forming apparatus

JP 2003-192213 A Japanese Patent No. 3417994

Claims (6)

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 against the edge of the sheet to align the edge, and a tapping roller that is disposed above the staple tray in the vicinity of the edge fence and moves the sheet toward the edge fence. And a return roller, a discharge means having a discharge claw for discharging the paper on the staple tray after the binding process, a transfer member provided in the transfer path toward the transfer path and the prestack tray, and a drive source of the discharge means A post-processing device comprising:
An inlet sensor that is disposed at the paper entrance in the transport path to detect the passage of paper and a paper presence sensor that is disposed in the vicinity of the edge fence in the staple tray to detect the presence or absence of paper are connected to the input side and output. A control unit to which the drive source of the return roller and the hitting roller and the drive source of the discharge means are connected on the side;
The return roller is positioned closer to the edge fence than the hitting roller and is positioned at a position where the distance from the edge fence is L2,
The control unit waits for the first sheet in the prestack tray when the two sheets are double-fed, and after the second sheet has passed through the conveyance path, the first sheet When the paper is fed out from the prestack tray and transported along the transport path together with the second sheet and transported toward the staple tray, transport of the sheet positioned above the rear end in the transport direction of the sheet positioned below is performed. The lower sheet is first transported to the staple tray by shifting the distance L1 such that L2 ≦ L1 with respect to the distance L2 between the edge fence and the return roller with respect to the rear end position in the direction. A post-processing apparatus that sets a driving state of a driving source. The post-processing apparatus according to claim 1, wherein
The control unit is configured to change the angle at which the paper is pushed up and faced to the staple tray by moving a discharge claw provided in the discharge unit in accordance with the presence or absence of paper by the paper presence / absence detection sensor. Post-processing device. The post-processing apparatus according to claim 1 or 2,
The post-processing device is characterized in that a material having a high coefficient of friction is used for the discharge claw. The post-processing apparatus according to any one of claims 1 to 3,
The post-processing apparatus, wherein the discharge claw is capable of moving the paper toward the return roller while the upper surface and the paper are in contact with each other when the discharge claw is moved. The post-processing apparatus according to any one of claims 1 to 4,
The post-processing apparatus, wherein the return roller is provided so as to be movable along a conveyance direction of the sheet with respect to the staple tray.   6. An image forming system, wherein the post-processing device according to claim 1 is arranged continuously with a paper discharge unit of the image forming apparatus.

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