JP2010143668A - Sheet stacking device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet stacking device and an image forming device which is free from rear-end-leaning. <P>SOLUTION: Sheets discharged on a discharge tray from a paper discharge part are prevented from leaning on a rear end of the paper discharge part by allowing the sheets to move close to and away from a restriction part for restricting an upstream end of the sheets stacked on the discharge tray in a sheet discharge direction and an aligning property of the upstream end in the sheet discharge direction of the sheets stacked on the discharge tray is improved. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sheet stacking apparatus and an image forming apparatus, and more particularly to a configuration for stacking discharged sheets satisfactorily.

  2. Description of the Related Art Conventionally, in image forming apparatuses such as printers, facsimiles, copiers, and multifunction printers, sheet stacking apparatuses that include a discharge tray on which discharged image formed sheets and read originals are stacked are generally known. When sheets are stacked on such a discharge tray, the upstream end (rear end) of the discharged sheet in the sheet discharge direction may lean against the rear end regulating plate or the discharge roller. Therefore, unevenness is provided on the outer peripheral portion of the discharge roller, and the trailing edge of the sheet discharged by the unevenness is kicked out and discharged to prevent the trailing edge of the sheet from leaning.

  In recent years, image forming apparatuses are compatible with various sheets from thin paper sheets to thick paper sheets according to user needs, and high quality images have been required for all sheets. However, with the discharge roller giving priority to the discharge stackability as described above, there is a possibility that a mark may be left on the image surface due to the unevenness of the outer peripheral portion of the discharge roller, particularly in a sheet on which a color image is printed with thick paper. Therefore, in order to maintain a balance between the image quality and the discharge stackability, it is necessary to strictly manage the size and shape of the irregularities on the outer periphery of the discharge roller.

  In view of this, there is one in which the rear end regulating plate is swung to prevent the rear end of the discharge sheet from leaning (see Patent Document 1). Hereinafter, a conventional sheet stacking apparatus of this system will be described with reference to FIG.

  In FIG. 17, when the sheet is discharged by the discharge roller pair 8, the trailing edge regulating plate 10 has a lower end so that the trailing edge leaning due to the upstream edge of the discharged sheet being caught in the trailing edge regulating plate 10 does not occur. Is swingable in the sheet discharge direction of the sheet.

Then, the trailing edge regulating plate 10 is swung to push the upstream end of the discharged sheet in the sheet discharge direction to the downstream side in the sheet discharge direction so that the sheets are satisfactorily stacked on the discharge tray 9.
JP 58-183559 A

  However, the configuration as shown in FIG. 17 is not sufficient as a countermeasure against leaning and has the following problems.

  As shown in FIG. 18, when a sheet having no stiffness (rigidity) such as a thin paper sheet is to be discharged, the sheet does not move even if the sheet is pushed out by the rear end regulating plate 10, and the bottom of the discharge roller pair 8. There is a possibility that the upstream end of the sheet in the sheet discharge direction may lean against the side roller. In such a state, the previously discharged sheet leans against the lower roller of the discharge roller pair 8 to block the discharge port, and the discharge of the succeeding sheet is prevented, or the preceding sheet that blocks the discharge port. Or sneak under. As a result, the succeeding sheet discharged from the discharge roller pair 8 may jam, the preceding sheet may be pushed out by the succeeding sheet and dropped from the discharge tray 9, or the sheet stacking order may be changed. Further, there is a possibility that the sheet is reversely fed into the inside of the apparatus through the gap between the lower roller of the discharge roller pair 8 and the rear end regulating plate 10 due to the rotation of the lower roller of the discharge roller pair 8. There is a risk of not only damage to the device but also damage to the device.

  Therefore, the present invention has been made in view of such a situation, and a sheet stacking apparatus and an image forming apparatus capable of reliably stacking a sheet on a discharge tray by preventing the trailing end of the discharged sheet from leaning. Is intended to provide.

  In order to achieve the above object, the present invention provides a discharge unit that discharges a sheet, a sheet stacking unit that stacks sheets discharged by the discharge unit, and an upstream end in the sheet discharge direction of the sheets stacked on the sheet stacking unit. And a sheet moving unit that moves the sheets stacked on the sheet stacking unit in a direction in which the sheets are separated and approached with respect to the limiting unit, and the sheet moving unit is disposed on the sheet stacking unit. The discharged sheet is moved in a direction away from the restricting portion, and then moved in a direction approaching the restricting portion.

  As in the present invention, the sheet discharged to the sheet stacking portion is moved away from the restricting portion that restricts the upstream end in the sheet discharge direction, and moved again toward the restricting portion, so that the upstream end in the discharge direction of the discharged sheet It is possible to prevent the trailing edge of the sheet from leaning and to stack sheets with good alignment.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

  FIG. 1 is a diagram illustrating a configuration of a laser beam printer which is an example of an image forming apparatus provided with a sheet stacking apparatus according to a first embodiment of the present invention.

  As shown in FIG. 1, the laser beam printer according to the present embodiment includes a photosensitive drum Cd, a scanner S that irradiates a laser beam on the photosensitive drum Cd based on image information, and forms an electrostatic latent image. A fixing device T for fixing the toner image transferred to the sheet is provided. The photosensitive drum Cd constitutes an image forming unit together with a developing unit that makes toner appear on the electrostatic latent image to be visualized, and a cleaning unit that removes toner remaining on the surface of the photosensitive drum Cd after transfer. The process cartridge C is detachably attached to A.

  Then, the sheet 3 fed from the cassette is transported to a transfer portion constituted by the photosensitive drum Cd of the process cartridge C and a transfer roller, and the toner image is transferred. Further, after the toner image is transferred to the sheet 3, the sheet 3 is conveyed to a fixing device T disposed downstream of the transfer unit in the sheet discharge direction, and the toner image is fixed on the sheet 3 by the fixing device T. A discharge roller pair 8 as a discharge unit is disposed downstream of the fixing device T in the sheet discharge direction. The discharge roller pair 8 discharges the sheet 3 onto a discharge tray 9 constituting a sheet stacking unit.

  Here, details of the sheet stacking unit in the present embodiment will be described.

  In FIG. 1, the discharge tray 9 sequentially stacks the sheets 3 discharged from the discharge roller pair 8 provided above the apparatus main body A. The discharge tray 9 is movable in the direction of the arrow 9a or the arrow 9b along the sheet stacking surface by the rotation of the tray cam 11 constituting the sheet moving means together with the tray spring 12 in the direction of the arrow 11a. The discharged sheet 3 slides on the inclined sheet stacking surface of the discharge tray 9, and the upstream end (rear end) of the sheet 3 in the sheet discharge direction hits the rear end restricting plate 10 as a restricting portion and is aligned. An arrow 9a is a direction away from the trailing edge regulating plate 10, and in the present embodiment, the direction is along the sheet stacking surface of the discharge tray 9 and coincides with the sheet discharge direction. An arrow 9b is a direction approaching the trailing edge regulating plate 10, and in the present embodiment, it is along the sheet stacking surface of the discharge tray 9 and in the opposite direction to the discharge direction.

  The tray cam 11 has an outer peripheral surface (cam surface) in contact with the discharge tray 9 and is provided to be rotated counterclockwise as indicated by an arrow 11a by a driving source such as a motor (not shown). The direction of rotation may be either counterclockwise or clockwise. Since the outer peripheral surface of the tray cam 11 is not fixed at a distance from the rotation center, the discharge tray 9 is reciprocated by rotating and engaging the outer peripheral surface of the short diameter portion and the long diameter portion of the tray cam 11 with the discharge tray 9. . The tray spring 12 presses the discharge tray 9 against the tray cam 11 so that the outer peripheral surfaces of the discharge tray 9 and the tray cam 11 are always engaged.

  FIG. 2 shows that the outer peripheral surface of the long diameter portion engages with the discharge tray 9 by the rotation of the tray cam 11 from the stacking position (broken line position) of the discharge tray 9 where the outer peripheral surface of the short diameter portion of the tray cam 11 contacts the discharge tray 9. The movement position (solid line position) when the discharge tray 9 moves in the direction of the arrow 9a.

  When the tray cam 11 rotates from the broken line position to the solid line position, the outer peripheral surface of the tray cam 11 that contacts the discharge tray 9 increases the diameter from the rotation center, thereby preventing the discharge tray 9 from being restricted against the pressing force of the tray spring 12. As shown in FIG. Thereby, the discharge tray 9 is moved to the movement position.

  Further, when the tray cam 11 rotates from the solid line position to the broken line position, the outer peripheral surface of the tray cam 11 that comes into contact with the discharge tray 9 becomes smaller in diameter from the center of rotation, so that the tray spring 12 causes the discharge tray 9 to move to the rear end regulating plate 10. Press in the direction to approach. Thereby, the discharge tray 9 is moved again to the loading position.

  As described above, the discharge tray 9 is held movably between the stacking position and the moving position by the action of the tray cam 11 and the tray spring 12 constituting the sheet moving means.

  Next, the operation when the discharge sheet is discharged onto the discharge tray 9 will be described with reference to FIGS.

  As shown in FIG. 3, the sheet discharged from the discharge roller pair 8 is not normally stacked on the discharge tray 9, and the upstream end of the discharged sheet in the sheet discharge direction leans against the discharge roller pair 8. Leaning may occur.

  Even in such a case, the tray cam 11 is rotated in the direction of the arrow 11a, and the discharge tray 9 is moved in the direction of the arrow 9a, whereby the discharge tray 9 and the discharge tray 9 are already loaded as shown in FIG. The moved sheet moves. In this way, the sheet already stacked on the discharge tray 9 moves and moves, and the upstream end of the sheet leaning against the discharge roller pair 8 falls on the discharge tray 9. To do. Even when sheets are not stacked on the discharge tray 9, the upstream end in the sheet discharge direction of the sheet leaning against the discharge roller pair 8 by the above-described operation is dropped onto the discharge tray 9, and the discharge tray 9 Good loading on top is possible.

  Here, the conditions under which the sheet leaning against the discharge roller pair 8 can drop onto the discharge tray 9 will be described.

  In FIG. 7, the position where the sheet leans against the discharge roller pair 8 is on the downstream side in the sheet discharge direction with respect to the nip portion (nip portion) of the discharge roller pair 8. Therefore, if the distance from the nip portion of the discharge roller pair 8 to the most downstream end in the horizontal direction of the discharge roller pair 8 is X1, the sheet leaning against the discharge roller pair 8 can be reliably discharged if the distance X1 or more can be moved. It becomes possible to drop and load on the tray 9.

In order to drop and stack the sheet leaning on the discharge roller pair 8 onto the discharge tray 9, the necessary movement amount X2 of the discharge tray 9 is defined as follows. The angle between the discharge tray 9 and the horizontal line is θ.
X2 ≧ X1 / cosθ
It becomes.

Accordingly, in the tray cam 11, when the discharge tray 9 is moved, the distance from the rotation center on the short diameter side to the outer peripheral surface is R1, and the distance from the rotation center on the long diameter side to the outer peripheral surface is R2.
R2-R1 = X2 ≧ X1 / cos θ
The relationship is established.

  With the above arrangement, as shown in FIG. 4, the sheet whose upstream end in the sheet discharge direction is leaning against the discharge roller pair 8 can be stacked on the discharge tray 9. However, as described above, the sheet whose upstream end in the sheet discharge direction is dropped on the discharge tray 9 is different from the sheet that is already stacked and stacked on the discharge tray 9 as shown in FIG. Will be misaligned.

  In such a case, it is necessary to perform an alignment operation on the stacked sheets on the discharge tray 9. Therefore, the tray cam 11 shown in FIG. 5 is rotated in the direction of the arrow 11b, and the discharge tray 9 is moved in the direction of the arrow 9b. In this way, the sheet on the discharge tray 9 can be moved in the direction of the trailing edge regulating plate 10. As shown in FIG. 5, the sheet that has fallen on the discharge tray 9 has its upstream end protruding in the sheet discharge direction toward the trailing edge regulating plate 10 than the already stacked sheets. I hit it. Then, by bringing the upstream end of the discharged sheet in the sheet discharge direction into contact with the rear end regulating plate 10, alignment of the discharged sheet and the upstream end of the stacked sheet in the sheet discharge direction is performed as shown in FIG. .

  As described above, when the sheet on the discharge tray 9 is moved in the direction of the rear end regulating plate 10, the sheet discharged on the discharge tray 9 hits the rear end regulating plate 10 as shown in FIG. It is necessary to avoid buckling and bending or entering into the gap. Therefore, it is desirable that the movement amount X2 of the discharge tray 9 is 20 mm or less so that even a thin sheet with weak waist does not buckle.

That is, the required movement amount X2 of the discharge tray 9 is
20 mm ≧ X2 ≧ X1 / cos θ
I can say that.

  However, in order to prevent buckled sheets from buckling, an uneven shape is formed in the width direction intersecting with the sheet discharge direction of the sheet stacking surface of the discharge tray 9 so that the discharged sheets are not corrugated. It is possible to further increase the movement amount X2 by sitting on the back.

  As shown in FIG. 10, the sheet is corrugated by making the width direction both ends intersecting the sheet discharge direction of the sheet stacking surface of the discharge tray 9 into a concave shape and making the central portion in the width direction into a convex protruding portion 9a. It can be loaded on the discharge tray 9 while being seated on. Furthermore, since only the projecting protrusion 9a can be moved by rotating the tray cam 11, the sheet can be moved while being seated, so that even if it is thin paper, it will not easily buckle against the rear end regulating plate 10. can do.

  Even with respect to the sheet leaning against the trailing edge regulating plate 10 by the above-described operation, it is possible to reliably drop the upstream end in the sheet discharge direction on the discharge tray 9 to achieve high alignment and stack. In the present embodiment, the movement amount X2 of the discharge tray 9 necessary to prevent the discharged sheet from leaning against the discharge roller pair 8 will be described. However, by further increasing the movement amount X2, not only the rear end leaning on the discharge roller pair 8 but also the rear end leaning on the rear end regulating plate 10 can be eliminated. In particular, in recent years, a discharge tray capable of stacking large-capacity sheets has been required, and the height between the nip portion of the discharge roller pair and the sheet stacking surface of the discharge tray, that is, the height of the trailing edge regulating plate tends to increase. Eliminating the back end leaning on the back end regulating plate leads to improved alignment and loadability.

  Here, the timing indicating the relationship from the start to the end time of the series of operations described above with the print job will be described with reference to the timing chart of FIG.

  3 to 5, a discharge sensor (not shown) is provided in the conveyance path from the fixing device T to the discharge roller pair 8. When the sheet passes through the conveyance path, the discharge sensor is the downstream end of the sheet in the sheet discharge direction. Or the upstream end is detected. As a result, the time when the downstream end of the sheet in the sheet discharge direction is sandwiched between the nip portion of the discharge roller pair 8 and the time when the upstream end of the sheet in the sheet discharge direction is discharged from the nip portion of the discharge roller pair 8 are predicted. .

  The upstream end of the preceding sheet (one page of the print job in FIG. 9) in the sheet discharge direction is discharged from the nip portion of the discharge roller pair 8 and is stacked on the discharge tray 9 with the rear end leaning on the discharge roller pair 8. If the preceding sheet stacked on the discharge tray 9 has passed through the nip portion of the discharge roller pair 8, the preceding sheet can be moved together with the discharge tray 9 by moving the discharge tray 9. Therefore, the discharge tray 9 starts to move from the loading position.

  The discharge tray 9 moves to the moving position before the downstream end of the subsequent sheet (page 2 of the print job in FIG. 9) contacts the upper surface of the preceding sheet stacked on the discharge tray 9. Further, the operation of returning from the moving position to the loading position is completed.

  The completion timing is determined by the friction when the downstream end of the subsequent sheet discharged from the discharge roller pair 8 comes into contact with the upper surface of the preceding sheet stacked on the discharge tray 9. This is so that it is not obstructed to return to the loading position together. That is, it is completed before the downstream end of the succeeding sheet (page 2 of the print job in FIG. 9) passes through the nip portion of the discharge roller pair 8 and contacts the upper surface of the preceding sheet stacked on the discharge tray 9. If you do.

  By the series of operations described above, it is possible to prevent the occurrence of back end leaning and to perform excellent discharge stacking that achieves both alignment and stackability.

  By the way, if the trailing edge lean detection means is provided on the discharge tray 9, the series of operations for eliminating the trailing edge leaning may be performed only when the trailing edge leaning occurs as described above, and unnecessary operations are omitted. It becomes possible.

  Next, a second embodiment of the present invention will be described with reference to the accompanying drawings.

  Since the main configuration of the laser beam printer (scanner S, process cartridge C, fixing device T, etc.) and the points related to the image forming process are the same as those in the first embodiment, description thereof will be omitted.

  Next, features of the configuration in the present embodiment will be described.

  In FIG. 11, a tray belt 13 serving as a sheet moving unit composed of an endless belt member is disposed on the discharge tray 9 on which the sheets discharged from the discharge roller pair 8 on the downstream side of the sheet discharge direction of the fixing device T are stacked. It is provided so as to protrude from the loading surface. Further, the upper surface of the tray belt 13 can be moved by stacking discharged sheets, and is moved in the direction of the arrow 13a or the arrow 13b by switching between forward and reverse rotation from a drive source such as a motor (not shown). To do.

  An arrow 13a is a direction away from the trailing edge regulating plate 10, and in the present embodiment, the direction is substantially parallel to the sheet stacking surface of the discharge tray 9 and coincides with the discharge direction. An arrow 13b is a direction approaching the rear end regulating plate 10, and in the present embodiment, indicates that the direction is substantially parallel to the sheet stacking surface of the discharge tray 9 and opposite to the discharge direction.

  Next, an operation when a sheet is discharged onto the discharge tray 9 will be described.

  As shown in FIG. 12, there are sheets that are not stacked and stacked on the discharge tray 9 from the discharge roller pair 8 and the upstream end in the sheet discharge direction leans against the discharge roller pair 8.

  Even in such a sheet, by rotating the tray belt 13 and moving the upper surface of the tray belt 13 in the direction of the arrow 13a, the sheets already stacked on the discharge tray 9 are moved as shown in FIG. Then, the portion of the sheet leaning on the trailing edge of the discharge roller pair 8 already stacked on the discharge tray 9 on the downstream end side in the sheet discharge direction leans against the discharge roller pair 8 as the tray belt 13 moves and moves. The upstream end of the sheet in the sheet discharge direction falls on the discharge tray 9.

  Here, the conditions under which the sheet can drop onto the discharge tray 9 will be described with reference to FIG.

  The position where the trailing edge of the sheet discharge roller pair 8 leans is downstream of the nip portion of the discharge roller pair 8 in the sheet discharge direction. Therefore, if the distance from the nip portion of the discharge roller pair 8 to the most downstream position in the horizontal direction of the discharge roller pair 8 is X1, the sheet leaning against the discharge roller pair 8 is surely discharged if the distance X1 or more can be moved. It can be dropped on the tray 9.

Therefore, the movement amount X2 of the tray belt 13 in the present embodiment required for dropping and stacking the sheet leaning against the discharge roller pair 8 on the discharge tray 9 is an angle formed by the discharge tray 9 and the horizontal line. If θ is
X2 ≧ X1 / cosθ
The relationship is established.

  Therefore, as shown in FIG. 14, the sheet whose upstream end in the sheet discharge direction is leaned against the discharge roller pair 8 can be stacked on the discharge tray 9. However, the sheet discharged onto the discharge tray 9 may be shifted in the sheet discharge direction from the sheets already stacked on the discharge tray 9.

  In such a case, it is necessary to perform an alignment operation on the stacked sheets on the discharge tray 9. Therefore, when the tray belt 13 is rotationally moved in the direction of the arrow 13b, the sheet on the discharge tray 9 can be moved toward the rear end regulating plate 10. As shown in FIG. 14, the upstream end of the sheet discharged in the sheet discharge direction on the discharge tray 9 protrudes toward the trailing edge regulating plate 10 from the upstream end of the sheet stacked in the sheet discharge direction. It abuts against the rear end regulating plate 10. Then, by bringing the upstream end of the discharged sheet in the sheet discharge direction into contact with the rear end regulating plate 10, as shown in FIG. 15, the alignment between the discharged sheet and the upstream end of the stacked sheet in the sheet discharge direction is achieved. Done.

  The series of moving operations of the discharge tray 9 described above eliminates back end leaning and enables discharge stacking that achieves both good alignment and stackability.

  Note that the start and end of the series of movement operations of the discharge tray 9 described above are the same as those described in the first embodiment, and thus are omitted.

  Further, as in the first embodiment, if a trailing edge leaning detection unit is provided on the discharge tray, the above-described series of movement operations of the discharge tray 9 can be performed only when the trailing edge remains. Well, it is possible to omit extra operations.

  In the embodiment described above, the configuration in which the sheet stacking apparatus according to the present invention is integrated into the image forming apparatus has been described. However, the sheet stacking apparatus according to the present invention is different from the image forming apparatus, such as a finisher. The present invention is effective even when applied to the sheet processing apparatus.

1 is a diagram illustrating a schematic configuration of a laser beam printer which is an example of an image forming apparatus including a sheet stacking apparatus according to a first embodiment of the invention. FIG. 3 is a diagram illustrating a configuration of a sheet stacking unit of the sheet stacking apparatus. FIG. 3 is a diagram illustrating a state of a discharge tray when a sheet is discharged to the discharge tray in the sheet stacking apparatus. FIG. 4 is a diagram illustrating a state of a discharge tray after sheets are discharged in the sheet stacking apparatus. FIG. 6 is a diagram illustrating a state of the discharge tray after sheets are stacked on the discharge tray in the sheet stacking apparatus. FIG. 6 is a diagram illustrating a state of the discharge tray when alignment of sheets on the discharge tray is finished in the sheet stacking apparatus. The figure for demonstrating the structure of the moving means of the discharge tray of the said sheet | seat stacking apparatus. The figure for demonstrating the movement amount of the discharge tray of the said sheet | seat stacking apparatus. 6 is a timing chart of sheet discharge and discharge tray movement of the sheet stacking apparatus. The figure explaining the uneven | corrugated shape of the sheet | seat stacking surface of the discharge tray of the said sheet stacking apparatus. FIG. 4 is a diagram illustrating a schematic configuration of a laser beam printer which is an example of an image forming apparatus including a sheet stacking apparatus according to a second embodiment of the invention. FIG. 4 is a diagram illustrating a state of a tray belt when a sheet is discharged to a discharge tray in the sheet stacking apparatus. FIG. 3 is a diagram illustrating a state of a tray belt after a sheet is discharged in the sheet stacking apparatus. FIG. 3 is a diagram illustrating a state of a tray belt after sheets are stacked on a discharge tray in the sheet stacking apparatus. FIG. 4 is a diagram illustrating a state of a tray belt at the end of alignment of sheets on a discharge tray in the sheet stacking apparatus. The figure for demonstrating the movement amount of the tray belt of the said sheet | seat stacking apparatus. FIG. 6 is a diagram illustrating a schematic configuration of a conventional sheet stacking apparatus. The figure which shows a mode that the sheet | seat leaning back in the conventional sheet stacking apparatus is extruded with a back end control board.

Explanation of symbols

A device main body C process cartridge Cd electrophotographic photosensitive drum S scanner T fixing device 8 discharge roller 9 discharge tray 10 rear end regulating plate 11 tray cam 12 tray spring 13 tray belt

Claims (9)

A discharge unit for discharging the sheet;
A sheet stacking unit for stacking sheets discharged by the discharge unit;
A regulation unit that regulates an upstream end in the sheet discharge direction of the sheets stacked on the sheet stacking unit;
Sheet moving means for moving the sheets stacked on the sheet stacking unit in a direction of separating and approaching the regulating unit,
The sheet moving means moves the sheet discharged to the sheet stacking portion in a direction away from the restricting portion, and then moves the sheet in a direction approaching the restricting portion. apparatus.   2. The sheet stacking apparatus according to claim 1, wherein the sheet moving unit moves the sheet stacking unit in a direction in which the sheet stacking unit moves away from and approaches the regulating unit.   3. The sheet stacking apparatus according to claim 1, wherein the sheet stacking unit includes a sheet stacking surface having a concavo-convex shape in a width direction intersecting a sheet discharge direction.   The sheet stacking unit has a projecting protrusion that forms the uneven sheet stacking surface, and the sheet moving means moves the projecting unit away from and toward the regulating unit. The sheet stacking apparatus according to claim 3.   The sheet moving means includes a cam that engages with the sheet stacking portion, and the cam moves the sheet stacking portion in a direction of separating and approaching the regulating portion by rotation. Item 5. The sheet stacking apparatus according to any one of Items 2 to 4.   2. The endless belt member that moves the sheet stacked on the sheet stacking surface of the sheet stacking unit in a direction in which the sheet stacking unit moves away from and approaches the regulating unit. Sheet stacking device.   The sheet moving means moves the sheet discharged from the discharge unit between a stacking position where the sheet discharged from the discharge unit is stacked and a moving position farther from the regulation unit than the stacking position. The sheet stacking apparatus according to claim 1, wherein the sheet stacking apparatus is a sheet stacking apparatus.   The moving means moves the sheet discharged from the discharge unit from the stacking position to the moving position after the upstream end in the sheet discharge direction of the sheet has passed through the discharge unit, and the sheet discharge direction of the next sheet to be discharged Moving the sheet discharged from the discharge unit from the moving position to the stacking position before the downstream end contacts the sheet stacking surface of the sheet stacking unit or the upper surface of the sheet stacked on the sheet stacking unit. 8. The sheet stacking apparatus according to claim 7, wherein Image forming means for forming an image on a sheet;
9. An image forming apparatus comprising: the sheet stacking apparatus according to claim 1 for stacking sheets on which images are formed.

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