JP2004269128A - Sheet processing equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet processing device capable of increasing the stacked amount of sheets and preventing each sheet from leaning. <P>SOLUTION: The sheet processing device is arranged so that sheets are stacked on a tray 504 and their trailing edges are put in alignment and is equipped with a swingable aligning wall 570 whereto the trailing edges of the sheets are pressed for alignment and a sheet surface sensor 525 for sensing the surface of the sheets stacked on the tray 504, wherein the sensor 525 is mounted on the trailing edge aligning wall 570. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet processing apparatus that stacks sheets on a stacking unit and aligns the stacked sheet ends.
[0002]
[Prior art]
Today, some image forming apparatuses include a sheet post-processing apparatus so that a plurality of sheets after image formation are collectively bound or bound and discharged.
[0003]
For example, as shown in FIG. 12, a sheet post-processing apparatus connected to an image forming apparatus such as a printing machine, a copying machine, a printer, etc., transfers a sheet S on which an image is formed by the image forming apparatus main body 200 into the sheet post-processing apparatus 500. Are temporarily stacked on the processing tray 540, where sheet post-processing such as alignment and binding of the sheets S is performed. Thereafter, the bundle of sheets is nipped by the bundle discharging means 580, and the bundle is discharged by rotating the rollers.
[0004]
In the above-described sheet post-processing apparatus, the sheets discharged in a bundle are stacked on a stack tray 504 having an inclined stacking surface as shown in FIG. 12, and the discharged sheets S move on the inclined stacking surface of the stack tray 504 by their own weight. The rear end of the sheet is aligned on the fixed rear end alignment wall 576. At this time, the sheet surface is detected by the sheet surface detection sensor 525 so that the uppermost sheet surface of the sheet bundle at the time of stacking the sheets is always at the fixed position, and the stack tray 504 is moved up and down. Further, the number of stacked sheets depends on the vertical operation stroke of the stack tray 504.
[0005]
In recent years, in a sheet post-processing apparatus, space saving and large-capacity stacking have been desired. In a sheet post-processing apparatus that achieves space saving and large-capacity loading, the rear end alignment wall is configured to swing between a vertical position and a retracted position inclined toward the upstream side in the transport direction, and the swinging rear end alignment wall is used to swing the rear end of the sheet. A configuration is adopted in which the edges are aligned and the sheet bundle is pressed back by the sheet returning member.
[0006]
With this configuration, it is possible to improve the sheet consistency on the stack tray even when the stack tray is substantially leveled, and convert the space where the tilt angle of the tray is approximately horizontal to a vertical operation stroke. Therefore, the number of sheets stacked on the stack tray can be increased.
[0007]
Further, in order to move the tray 504 up and down according to the stacking amount of the sheet bundle on the stack tray 504, a sheet surface detection sensor for detecting the stacking amount of the sheet bundle is provided. This sensor causes a rotatable lever to protrude from the wall to the sheet side, and when this lever is pressed by the loaded uppermost sheet, the stack tray 504 is moved downward as a predetermined amount of sheets are loaded. I have.
[0008]
[Problems to be solved by the invention]
However, in the related art, the sheet surface detection sensor is disposed on a fixed wall located below the swinging rear end alignment wall. For this reason, the sheet surface is detected in a state where the stack tray 504 is at a lower position, and the vertical stroke with respect to the lower limit position of the stack tray 504 is reduced by the lower position of the sheet surface detection sensor. The loading capacity was decreasing.
[0009]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a sheet processing apparatus capable of increasing a sheet stacking amount and preventing a sheet from leaning.
[0010]
[Means for Solving the Problems]
A typical configuration according to the present invention for achieving the above object is to stack a sheet on a stacking unit and align the edge of the stacked sheet by pressing the edge of the sheet in the sheet processing apparatus. And a sheet detecting means for detecting the uppermost sheet surface of the sheets stacked on the stacking means, wherein the sheet detecting means is disposed on the end aligning means. It is characterized by the following.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an image forming apparatus including a sheet processing apparatus to which the present invention is applied will be specifically described with reference to the drawings.
[0012]
Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an image forming apparatus main body 200 equipped with a sheet post-processing apparatus 500 according to an embodiment of the present invention, FIG. 2 is a top view of the sheet post-processing apparatus 500, and FIG. FIG.
[0013]
(overall structure)
As shown in FIG. 1, the sheet S on which an image has been formed, which is disposed above the image forming apparatus main body 200 and below the document reading apparatus 100 and has been discharged from the image forming apparatus main body 200, is temporarily processed by the processing tray 540. A sheet post-processing apparatus 500 that stacks the processed sheets S on the stack tray 504 disposed substantially horizontally after stacking the sheets S thereon, performing post-processing such as stapling, alignment, and the like will be described as an example. .
[0014]
However, in this embodiment, a sheet post-processing device that aligns and stacks the image-formed sheets S discharged from the image forming apparatus main body 200 on the stack tray 504 is directly connected to the image forming apparatus main body 200 without passing through the processing tray 540. This is also effective in the case where the sheet post-processing apparatus 500 is mounted outside the image forming apparatus main body 200.
[0015]
In FIG. 1, reference numeral 500 denotes a sheet post-processing apparatus mounted on the image forming apparatus main body 200, and an automatic document reading apparatus 100 is mounted on the upper part of the image forming apparatus main body 200. The image forming apparatus according to the present embodiment includes the image forming apparatus main body 200, the sheet post-processing apparatus 500, and the automatic document reading apparatus 100. However, the sheet post-processing apparatus 500 may not include the processing tray 540. .
[0016]
As shown in FIG. 1, the image forming apparatus main body 200 is equipped with an original reading unit 150 having an original reading unit 150 and an original feeding device 101 for automatically feeding an original to the original reading unit 150. The automatic document reading apparatus 100 separates an original set upward, feeds the original one sheet at a time from the first page to the left, and conveys the original onto a platen glass 102 via a curved path. Is read, and then discharged to the discharge tray 112.
[0017]
The light of the lamp of the scanner unit 104 is applied to the original, and the reflected light from the original is guided to the image sensor 109 via the first mirror 105, the second mirror 106, and the lens 107, so that the original is read. The image of the document read by the image sensor 109 is subjected to image processing, sent to the exposure control unit 202, and emitted a laser beam.
[0018]
Next, the laser light is reflected by the rotating polygon mirror, and is again turned back by the reflecting mirror to irradiate the photosensitive drum 203 serving as an image forming means whose surface is uniformly charged, and the electrostatic latent image is formed. An image is formed. After the electrostatic latent image on the photosensitive drum 203 is developed by the developing device 205, it is transferred as a toner image onto a sheet S composed of paper, an OHP sheet, or the like.
[0019]
The sheet S is appropriately and selectively fed out of the sheet cassettes 231, 232, 233, and 234 by a pickup roller 238 constituting a sheet feeding unit, is separated by a separating unit 237, and is fed one by one. After the skew is corrected, the toner is sent to the transfer position in synchronization with the rotation of the photosensitive drum 203, and the toner image formed on the photosensitive drum 203 is transferred to the sheet S via the transfer belt 211.
[0020]
Thereafter, the sheet S is guided to the fixing roller pair 206, and the toner image transferred to the sheet S after being heated and pressed by the fixing roller pair 206 is permanently fixed. The upper fixing claw and the lower fixing claw are in contact with the fixing roller pair 206, respectively, whereby the sheet S is separated from the fixing roller pair 206.
[0021]
The separated sheet S is conveyed to the outside of the image forming apparatus main body 200 by the main body side discharge roller pair 207, and is guided to the sheet post-processing apparatus 500 connected to the image forming apparatus main body 200.
[0022]
(Sheet post-processing equipment)
Next, the configuration of the sheet post-processing apparatus 500 will be specifically described.
[0023]
In FIG. 1, the sheet post-processing apparatus 500 includes a processing tray 540, which is a sheet stacking unit disposed on the upstream side in the sheet conveyance direction, and a stack tray 504 disposed substantially horizontally on the downstream side in the sheet conveyance direction. The sheet S discharged from the pair of discharge rollers 207 on the main body side of the forming apparatus main body 200 is conveyed in the sheet post-processing device 500, post-processed by the processing tray 540, and stacked on the stack tray 504. .
[0024]
The post-processing mode performed on the processing tray 540 includes a sort mode for sorting a plurality of sets, a staple mode (staple) mode for binding a plurality of sheets by the staple unit 510, and the like. Selected and set by means.
[0025]
It is also possible to select a staple binding position such as one-point binding or two-point binding, and the staple unit 510 moves from the setting contents such as the sheet size and the binding position to the actual staple binding position.
[0026]
As shown in FIGS. 2 and 3, the sheet S discharged from the image forming apparatus main body 200 is directed toward the stack tray 504 by a discharge unit 508 including a discharge roller 508a on the sheet post-processing apparatus 500 side and a discharge roller 508b driven by the discharge roller 508a. When the rear end of the sheet S passes through the discharge section 508, the rear end of the sheet S is dropped onto the processing tray 540 by the swing roller 550, and is pinched by the swing roller 550 and the driven roller 571. Is done.
[0027]
<Swing roller configuration>
The operation of the swing arm and the swing roller 550 will be described with reference to FIGS.
[0028]
As shown in FIG. 4, the swing roller 550 is attached to a swing arm 551 that can swing vertically about a swing roller shaft 552. Drive from a swing arm drive motor (not shown) is transmitted to the swing arm shaft 553 via a swing cam 554, and when the swing arm drive motor rotates, the swing arm 551 is integrated with the swing cam 554. Then, it swings up and down around the swing roller shaft 552. A swing arm extension spring 555 is mounted on the swing arm 551 to assist upward swing.
[0029]
As shown in FIG. 2, the swing roller 550 is connected to a swing roller drive motor (not shown) from a swing roller shaft 552 via a swing roller drive belt 556 and a swing roller driven pulley 557. The rocking roller 550 is rotated by the driving of.
[0030]
<Swing roller operation>
The home position of the oscillating roller 550 is set at an upper portion that does not come into contact with the sheet S discharged onto the processing tray 540 by the discharge unit 508 (see FIG. 4A). When the sheet S is discharged from the discharge section 508, the swing arm 551 is driven by the swing arm drive motor and rotates around the swing roller shaft 552 in the counterclockwise direction in FIG. The roller 550 descends and presses the rear end of the sheet S with the swing roller 550 to drop the rear end of the sheet into the processing tray 540 (see FIG. 4B).
[0031]
The oscillating roller 550 forms a nip with the driven roller 571, and rotates counterclockwise in response to the driving of the oscillating roller drive motor, so that the rear end of the sheet S on the processing tray 540 returns to the return belt 560. The sheet S is pulled in along the lower guide 561 in the direction opposite to the previous conveying direction until the sheet S contacts the sheet S (see FIG. 4C). Thereafter, the swing roller 550 moves up to the home position again, and prepares for discharging the next sheet S (see FIG. 4A).
[0032]
<Return belt operation>
Next, the operation of the return belt 560 will be described with reference to FIGS.
[0033]
The return belt 560 is supported vertically by the discharge roller shaft 509 and is normally set at a position where it comes into contact with the sheet S on the processing tray 540. As shown in FIG. 3, the return belt 560, which is at least one or more sheet feed rotating bodies, is disposed perpendicular to the direction in which the sheet S abuts against the sheet trailing end stopper 562. The belt member conveys the sheet S in the direction of the sheet rear end stopper 562 by rotating the discharge roller shaft 509 in the counterclockwise direction in FIG. (See FIG. 5A).
[0034]
Further, the return belt 560 is adapted to escape in the thickness direction of the sheets according to the number of sheets S stacked on the processing tray 540 (see FIG. 5B).
[0035]
As described above, due to the rotation of the swing roller 550 and the return belt 560 in the counterclockwise direction, the rear end of the sheet S is positioned at the end of the processing tray 540, and receives the sheet S on the processing tray 540. Is sent to the rear end stopper 562 of the sheet S, and the sheet S is aligned one by one in the sheet conveying direction.
[0036]
<Sheet width direction alignment operation>
The alignment in the sheet width direction will be described with reference to FIG.
[0037]
The front alignment plate 541 and the rear alignment plate 542 are driven by a front alignment motor and a rear alignment motor (not shown), and move in a direction parallel to the discharge roller shaft 509.
[0038]
When the sheet post-processing apparatus 500 is not in operation, the front alignment plate 541 and the rear alignment plate 542 stand by at positions where they detect a front alignment home position sensor and a rear alignment home position sensor (not shown). This position is called an alignment home position position, and is set to a position where the sheet does not hit the alignment plate when the sheet is conveyed.
[0039]
The alignment plates 541 and 542 move to a standby position according to the sheet size before the sheet is conveyed from the image forming apparatus main body 200. After the sheets S are aligned in the transport direction as described above, the alignment plates 541 and 542 are moved to alignment positions in the post-processing mode set before the start of the job, whereby alignment in the sheet width direction is performed.
[0040]
For example, in the case of the sort mode, when aligning the Nth sheet in the width direction, the front alignment plate 541 waits at the reference position, and the rear alignment plate 542 moves from the standby position to the sheet alignment position, thereby determining the front side as the reference. The sheet is discharged to the stack tray 504 by the operation described later. When aligning the (N + 1) th sheet, the rear aligning plate 542 waits at the reference position, and the front aligning plate 541 moves from the standby position to the sheet aligning position to perform alignment based on the rear side, and stacks. The sheet is discharged to the tray 504. Thus, the sheets can be stacked on the stack tray 504 in a sorted state each time the bundle is discharged.
[0041]
Of course, it is also possible to perform alignment based on the center position of the sheet. In that case, the alignment is performed by moving both of the alignment plates 541 and 542 from the standby position to the alignment position based on the center position.
[0042]
When the staple binding mode is selected, the above-described width alignment operation is performed at a position corresponding to the set staple binding position.
[0043]
When the staple binding mode is selected, the staple binding operation is subsequently performed. The stapler unit 510 performs a stapling operation by driving a staple clinch motor (not shown). The stapler unit 510 can be moved in the front-rear direction by driving a staple slide motor.
[0044]
When the job is started, the stapler unit 510 moves to the actual staple binding position determined from the contents of the staple binding position set before the start of the job and the sheet size. The stapler unit 510 performs a staple binding operation on the aligned sheet bundle S that has been subjected to the width direction alignment described above.
[0045]
<Bunch discharging means>
Next, the bundle discharging means will be described with reference to FIG.
[0046]
After the alignment in the sheet conveying direction, the alignment in the sheet width direction, and the staple binding operation, the swing roller 550 is driven by the motor and descends around the swing roller shaft 552 until it comes into contact with the sheet bundle S (FIG. 6 (a)), after forming the nip with the driven roller 571, rotate in the clockwise direction, and convey the sheet bundle S until the rear end reaches the vicinity of the upper end of the rear end alignment wall 570 as the end alignment means. The operation is stopped (see FIG. 6B).
[0047]
Thereafter, the swing roller 550 separates from the sheet bundle S and returns to the home position (see FIG. 6C). At the same time, the rear end alignment wall 570 swings in a direction opposite to the sheet conveying direction by a swinging structure described later.
[0048]
<Rear end alignment wall swing configuration>
Here, the swing configuration of the rear end alignment wall 570 will be described. As shown in FIG. 7, the rear end alignment wall 570 is rotatably mounted around a shaft 573, and a rotary shaft 590 for rotating a sheet return member described later is mounted on the upper end, and the rotary shaft 590 is provided. A gear 800b is fixed to one end in the longitudinal direction. This gear 800b meshes with a drive gear 808 attached to the shaft 573, which serves as a swing center of the rear end alignment wall 570, via a gear train (not shown), and the driving force of a motor (not shown) is transmitted to the drive gear 808. Then, the gear 800b rotates.
[0049]
A cam 800a is fixed at a position deviated from the rotation center of the gear 800b, and the cam 800a is configured to abut on a cam rail 805 provided on the apparatus main body. A tension spring 512 is attached to the lower end of the rear end alignment wall 570, and the rear end alignment wall 570 is urged in the clockwise direction in FIG. It comes into contact with the cam rail 805.
[0050]
Accordingly, when the driving force is transmitted to the gear 800b and the gear 800b rotates in the direction of the arrow A, the posture of the rear end alignment wall 570 is changed by the cam rail 805 as shown in FIGS. Is rotated (swinged) around the center. The position of the cam 800a is detected by a home position sensor (not shown). When the rear end alignment wall 570 is stopped, the cam 800a is stopped at a home position where the wall 570 is vertical.
[0051]
<Sheet trailing edge alignment>
Next, means for discharging the sheet bundle S on the processing tray 540 onto the stack tray 504, aligning and stacking the sheets will be described with reference to FIG.
[0052]
The rear end alignment wall 570 can swing about the shaft 573 as described above. Then, in a state where the rear end of the sheet bundle S discharged by the bundle discharging unit is in contact with the upper end of the rear end alignment wall 570 (see FIG. 6B), the rear end alignment wall 570 is retracted upstream in the sheet conveyance direction. Then, the rear end of the sheet bundle S is brought into contact with the slope of the rear end alignment wall 570 (see FIG. 8A).
[0053]
In the process of returning the retracted rear end alignment wall 570 to the home position around the pivot axis of rotation, the rear end of the sheet bundle S is pressed horizontally by the rear end alignment wall 570 to align the rear end of the sheet bundle S. While stacking the sheet bundle S on the stack tray 504 (see FIGS. 8B and 8C).
[0054]
The sheet bundle placed on the stack tray 504 is pulled back by the sheet return member 583 to the rear end alignment wall 570 side after the sheet bundle is discharged, and is pressed down from the upper surface of the sheet bundle. The sheet return member 583 is a paddle-shaped member made of an elastic member (hereinafter, referred to as a “paddle”), and rotates around a paddle rotation shaft 590 (see FIG. 8) extending in the rear end alignment wall. Each time the sheet bundle is discharged onto the stack tray 504 by the swing roller 550, the paddle 583 makes one turn in the counterclockwise direction, so that the discharged sheet bundle is moved toward the rear end alignment wall 570 every time. The sheet can be pulled back and the rear end of the sheet bundle can be pressed.
[0055]
Note that the paddle 583 is held in a state as shown in FIGS. 6A and 6B except during the sheet returning operation, and holds the sheet. The position of the member at this time is detected by a paddle home position sensor (not shown).
[0056]
<Stack tray operation>
Next, the operation of the stack tray 504 will be described with reference to FIG.
[0057]
FIG. 9 is a diagram schematically illustrating the stack tray 504 and the detection positions of the sheet bundle stacked on the stack tray 504, the sheet surface detection sensor, and the tray detection sensor.
[0058]
Both the swingable rear end alignment wall 570 and the fixed rear end alignment wall 576 serve as a stacking reference plane for a sheet bundle stacked on the stack tray. P1 indicates a detection position of a sheet surface detection sensor described later, and P2 indicates a detection position of a tray detection sensor (not shown). Note that P1 and P2 in the figure are blacked out when the corresponding sensors are ON, and are outlined when they are OFF.
[0059]
FIG. 9A shows the position of the stack tray 504 during normal standby. Control is performed so that the mounting surface when the sheet bundle is discharged is between P1 and P2. That is, when the stack of sheets is stacked, the position of the upper surface of the stack of sheets S is between P1 and P2, and when the stack of sheets is not stacked, the stacking surface of the stack tray 504 is set. Is controlled between P1 and P2.
[0060]
Increasing the interval between P1 and P2 is effective in reducing the number of times the stack tray is activated. In the present embodiment, the position of P1 is determined by the stacking capacity of the stack tray 504 when the sheet bundle is discharged. The position of P2 is set to the lowest position in a range where the consistency can be guaranteed.
[0061]
As shown by the broken line in FIG. 9B, the tray is located at a position where both the sheet surface detection sensor and the tray detection sensor are turned off immediately after the sheet bundle S is removed. When the control unit recognizes that both sensors have been turned off, it drives the stack tray upward. Then, when the tray is raised to the position P2 and the tray detection sensor is turned on, the driving stops. The position of the tray when stopped is shown by a solid line in the figure.
[0062]
The sheet bundle is repeatedly discharged from the state of FIG. 9B, and when the uppermost surface of the stacked sheet bundle becomes higher than P1, that is, as shown in FIG. 9C, the tray detection sensor and the sheet surface When both of the detection sensors are turned on, the stack tray is driven downward until the sheet surface detection sensor is turned off.
[0063]
FIG. 9D shows a state when the sheet surface detection sensor is turned off and the lowering operation is stopped.
[0064]
As described above, the stop position when the stack tray 504 is lifted, such as after the sheet bundle is removed, is set to P2, and the stop position when the stack tray 504 is lowered when the stack discharge is repeated is set to P1, whereby the sheet is The stack tray is driven until the top surface of the sheet bundle reaches a predetermined position (in this embodiment, the upper limit position where the stackability and consistency of the stack tray can be guaranteed) from the state in which the stack is not stacked and the stack discharge is repeated. This can save power and extend the life of the motor driving the stack tray.
[0065]
Further, as another embodiment, the control of stopping the lowering operation may be performed after the sheet surface detection sensor is turned off and further lowered a predetermined distance, and then stopped above P2. This enables more bundles of sheets to be discharged before the next stack tray lowering operation is started, which is more effective.
[0066]
<Relationship between sheet surface detection sensor and rear end alignment wall>
As described above, in the present embodiment, when the gear 800b fixed to the paddle rotation shaft 590 attached to the rear end alignment wall 570 rotates, the paddle 583 rotates and the rear end alignment wall 570 swings. It has become.
[0067]
Further, the rear end alignment wall 570 is provided with a sheet surface detection sensor as a sheet detection unit for detecting the surface of the sheet stacked on the stack tray 504 as described above. As shown in FIG. 10A, the sheet surface detection sensor 525 is constituted by a lever member rotatable about the same axis as the paddle rotation shaft 590, and is pressed by the sensor spring 530 with an appropriate urging force, and is moved to the home position. Is mounted so as to protrude outward (toward the seat) from the wall surface of the rear end alignment wall 570.
[0068]
Next, using FIGS. 10A to 10E and FIGS. 11A to 11E, the operation in which the rear end alignment wall 570 and the paddle 583 rotate in synchronization with each other is described by a sheet surface detection sensor. The description will be made in correspondence with the position 525. FIG. 10 shows a case where the shape of the sheet surface detection sensor 525 and the spring force of the sensor spring 530 are optimized, and FIG. 11 shows a case where the shape of the sheet surface detection sensor is the same and the spring force is strong.
[0069]
The stack tray 504 is configured to be able to be moved up and down by a driving unit (not shown) in order to keep the upper surface height of the stacked sheet bundle S constant, and the sheet surface detection sensor 525 detects the sheet stacked on the stack tray 504. This is for detecting the height of the upper surface of the bundle S.
[0070]
FIGS. 10A and 11A show the state before the operation is started. At this time, the rear end alignment wall 570 is in the vertical position, and the sheet surface detection sensor 525 does not detect the uppermost sheet surface. ), And the paddle 583 faces downward.
[0071]
FIGS. 10B and 11B are diagrams in which the drive is transmitted and the paddle 583 starts rotating in the direction of arrow A. At this time, the cam 800a rotates in the same direction along the cam rail 805 by the urging force of the spring 512 (see FIG. 7), and the rotation of the cam 800a and the movement along the cam rail 805 causes the rear end alignment wall 570 to move in the direction indicated by the arrow B. In the direction around the axis 573. Further, in FIG. 10B, the sheet surface detection sensor 525 also starts to retreat inside the wall surface of the rear end alignment wall 570 due to its own weight, but in FIG. 11B, the sheet surface detection sensor 525 has a spring force greater than its own weight. Is stronger than that of the rear end alignment wall 570, so that the rear end alignment wall 570 protrudes toward the seat.
[0072]
FIGS. 10C and 11C show a state in which the rear end alignment wall 570 is completely retracted (inclined). The inclination angle of the rear end alignment wall 570 is the maximum, and the paddle 583 faces upward. At this time, the paddles 583 are synchronized with each other so as to maintain an angle as shown in the figure not in contact with the sheet bundle.
[0073]
Also, in FIG. 11C, the sheet surface detection sensor 525 protrudes outward (to the side of the sheet) from the wall surface of the rear end alignment wall 570 due to the spring force of the sensor spring 530, but in FIG. Reference numeral 525 retreats inward from the rear end alignment wall 570 (on the opposite side of the sheet). This can be achieved by setting the spring force to such a degree that the sheet surface detection sensor 525 completely retracts inside the rear end alignment wall 570 by its own weight when the rear end alignment wall 570 is at the retracted position.
[0074]
FIGS. 10D and 11D show that the paddle 583 further rotates, and the rear end alignment wall 570 starts rotating in the direction in which the sheet bundle is pushed out by the cam 800a and the cam rail 805. From this state, a force for holding the sheet S by the paddle 583 starts to be generated. The sheet pressing force increases as the paddle 583 rotates. As shown in FIG. 10D, the rear end of the sheet is pushed out toward the stack tray 504 by the rear end alignment wall 570, but is gradually pressed from above by the paddle 583, so that the sheet is separated from the rear end alignment wall 570. I can't go. Further, since the sheet S has room to escape to the stack tray 504 side until the paddle 583 completes the rotation, the rear end of the sheet does not buckle due to too strong force in the returning direction.
[0075]
However, as shown in FIG. 11D, when the sheet surface detection sensor 525 protrudes outward (toward the sheet) from the rear end alignment wall 570, not only the rear end of the sheet S is not aligned but also the paddle The direction of the force applied by 583 acts in the direction of returning (the direction of climbing the inclination of the rear end alignment wall 570) from the direction of pressing the sheet S downward. Therefore, as shown in FIG. 11E, the sheet S is sandwiched between the sheet surface detection sensor 525 and the paddle 583, and when the rear end alignment wall 570 returns to the vertical position, the sheet S leans on the rear end alignment wall 570. Would.
[0076]
FIGS. 10E and 11E show a state in which the paddle 583 and the sheet rear end alignment wall 570 rotate in synchronization, and the rear end alignment, sheet return, and sheet bundle pressing of the sheet bundle are completed. . The paddle 583 is facing downward again, and the trailing end alignment wall 570 has returned to the vertical position and stopped.
[0077]
As shown in FIG. 10E, if the shape and the spring force of the sheet surface detection sensor 525 are optimized, the uppermost sheet surface of the sheet bundle stacked on the stack tray 504 is detected by the sheet surface detection sensor 525. In this case, the height of the uppermost sheet surface on the stack tray is always kept within a certain range by lowering the stack tray 504 by a driving unit (not shown) until the sheet surface detection sensor 525 stops detecting the sheet surface. This makes it possible to maintain the stackability even in the next sheet discharging and stacking operation.
[0078]
Of course, depending on the material and configuration of the sheet surface detection sensor 525, if the spring force is too weak, the sheet surface detection sensor 525 remains retracted inside the rear end alignment wall 570 due to the frictional resistance of the sliding portion of the sheet surface detection sensor 525. In other words, the sensor may erroneously detect. Also, as shown in FIG. 11E, when the sheet S is sandwiched between the paddle 583 and the sheet surface detection sensor 525, the stack tray 504 is set to the lower limit sensor (not shown) because the sheet surface detection sensor 525 continues to react. , And the sheet S remains leaning against the rear end alignment wall 570, so that the stackability is deteriorated.
[0079]
As described above, in the configuration having the sheet surface detection sensor 525 and the paddle 583 on the oscillating sheet rear end alignment wall 570, the shape and the spring force of the sheet surface detection sensor 525 are optimized, and the rear end alignment wall 570 is formed. When the swing retreat position is set, the sheet surface detection sensor 525 is retracted inside the wall surface of the rear end alignment wall 570, so that the stackability can be improved.
[0080]
When the sheet surface detection sensor 525 is installed on the fixed rear end alignment wall 576 located below the rear end alignment wall 570 that oscillates to prevent the sheet from leaning, the rear end that oscillates as described above. Compared to the case where the sheet surface detection sensor 525 is provided on the alignment wall 570, the uppermost sheet surface is detected in a state where the stack tray 504 is below, and if the lower limit position of the stack tray 504 is the same, the vertical stroke is It goes without saying that the sheet stacking capacity is reduced because the sheet surface detection sensor 525 is reduced by the amount below.
[0081]
As described above, by disposing the sheet surface detection sensor 525 on the swinging sheet trailing end alignment wall 570, the vertical operation stroke of the stack tray 504 can be increased, and the stacking capacity can be increased.
[0082]
Further, a paddle 583 for holding the sheet bundle while returning the sheet bundle is provided on the swinging rear end alignment wall 570. When the swinging rear end alignment wall 570 is in the inclined retracted position, the sheet surface detection sensor 525 causes the rear end alignment wall to move. By retreating to the inside of the sheet 570, the sheet trailing edge alignment is improved, and the stackability is improved.
[0083]
Further, it is possible to provide a sheet post-processing apparatus in which the stacking capacity is increased and the stacking property is improved, and the space and the capacity of the entire system including the image forming apparatus can be reduced.
[0084]
(Embodiment)
Next, preferred embodiments to which the present invention can be applied are listed below.
[0085]
[Embodiment 1] In a sheet processing apparatus for stacking sheets on a stacking unit and aligning the end of the stacked sheets,
End aligning means capable of swinging to press and align the sheet end,
Sheet detection means for detecting the uppermost sheet surface of the sheets stacked on the stacking means,
Has,
2. A sheet processing apparatus according to claim 1, wherein said sheet detecting means is disposed in said end aligning means.
[0086]
[Embodiment 2] The sheet end aligning means has a sheet end aligning wall for pressing and aligning an edge of the sheet, and the sheet trailing end aligning wall swings between a vertical position and an inclined position. The sheet processing apparatus according to the first embodiment, wherein:
[0087]
[Embodiment 3] The sheet processing apparatus according to Embodiment 1 or Embodiment 2, wherein the sheet surface detection means has a rotatable detection lever.
[0088]
[Embodiment 4] The detection lever is located closer to the loading means than the wall surface of the rear end alignment wall, so that the uppermost sheet surface can be detected when the sheet rear end alignment wall is in the vertical position. 4. The sheet processing apparatus according to claim 3, wherein the sheet does not project from the wall surface of the sheet rear end alignment wall toward the sheet when the sheet rear end alignment wall is in the inclined position.
[0089]
[Embodiment 5] The stacking means is configured to be displaceable in accordance with the stacking amount of sheets to be stacked, and when the sheet surface detecting means detects the uppermost sheet surface, the stacking means determines that the sheet surface detecting means has the uppermost sheet. The sheet processing apparatus according to any one of Embodiments 1 to 4, wherein the sheet processing apparatus is configured to be displaced to a position where a surface is not detected.
[0090]
[Sixth Embodiment] A sheet according to any one of the first to fifth embodiments, further comprising a sheet pressing unit for pressing the sheet when the sheet edge is aligned by the end alignment unit. Processing equipment.
[0091]
[Seventh Embodiment] The sheet processing apparatus according to the sixth embodiment, wherein the sheet pressing means and the end aligning means are driven synchronously.
[0092]
[Embodiment 8] In an image forming apparatus that performs predetermined processing on a sheet on which an image is formed by an image forming unit and discharges and stacks the sheet,
An image forming apparatus, comprising: the sheet processing apparatus according to any one of Embodiments 1 to 7 for processing an image-formed sheet.
[0093]
【The invention's effect】
As described above, according to the present invention, it is possible to stack sheets on the stacking means, and to improve the sheet trailing end alignment when aligning the stacked sheet edges, thereby improving the sheet stackability. Become. Further, it is possible to increase the vertical operation stroke of the loading means and increase the loading capacity.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view of an image forming apparatus including a sheet post-processing apparatus according to an embodiment of the present invention.
FIG. 2 is a top view of the sheet post-processing apparatus.
FIG. 3 is a cross-sectional view illustrating a mechanism for moving a swing roller and an alignment member provided on a processing tray.
FIG. 4 is a cross-sectional view illustrating the operation of the swing roller.
FIG. 5 is a sectional view showing the operation of the return belt.
FIG. 6 is a cross-sectional view illustrating a sheet bundle discharging operation.
FIG. 7 is a cross-sectional view illustrating a swing configuration of a rear end alignment wall.
FIG. 8 is a cross-sectional view illustrating an operation of aligning the rear end of the sheet bundle.
FIG. 9 is a schematic diagram showing a stack tray operation.
FIG. 10 is a schematic diagram showing synchronization of sheet surface detection and operation of a rear end alignment wall and a paddle when a spring force is appropriate.
FIG. 11 is a schematic diagram showing synchronization between sheet surface detection and movement of a rear end alignment wall and a paddle when a spring force is strong.
FIG. 12 is a cross-sectional view illustrating the overall configuration of a conventional sheet post-processing apparatus.
[Explanation of symbols]
S ... sheet
100 Document reading device
101: Document feeder
102… Platen glass
104… Scanner unit
105… First mirror
106… second mirror
107 ... lens
109… Image sensor
112 ... discharge tray
150… Document reading section
200: Image forming apparatus main body
203: Photoconductor drum
205… Developer
206: fixing roller pair
207… Main body side discharge roller pair
211… Transfer belt
231,232,233,234 ... sheet cassette
237 ... separation means
238… Pickup roller
500… Sheet post-processing device
504: Stack tray
508 ... discharge section
508a ... discharge roller
508b… Discharge roller
509 ... discharge roller shaft
510… Staple unit
512 ... spring
525… Sheet surface detection sensor
530… Sensor spring
540: Processing tray
541… front alignment plate
542… rear alignment plate
550… Swing roller
551… Swing arm
552: Swing roller shaft
553… Swing arm shaft
554… Swing cam
555: swing arm extension spring
556… Swing roller drive belt
557… Swing roller driven pulley
560… Return belt
561… Lower guide
562… Sheet rear end stopper
570… Rear end matching wall
571… driven roller
573… axis
576… Fixed rear end alignment wall
583… paddle
590… paddle rotation shaft
800a… Cam
800b ... gear
805… Cam rail
808… Driving gear

Claims (1)

In a sheet processing apparatus for stacking sheets on a stacking unit and aligning the stacked sheet ends,
End aligning means capable of swinging to press and align the sheet end,
Sheet detection means for detecting the uppermost sheet surface of the sheets stacked on the stacking means,
Has,
2. A sheet processing apparatus according to claim 1, wherein said sheet detecting means is disposed in said end aligning means.

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