JP2020083506A - Sheet discharging device, sheet post-processing device including the same, and image forming system - Google Patents

Abstract

To provide a sheet discharging device capable of suppressing sheet push-out or misalignment caused by interference between an already discharged sheet and a leading-edge of a subsequent sheet, a sheet post-processing device including the same, and an image forming system.SOLUTION: A sheet discharging device 150 includes: a discharging tray 50; an alignment mechanism 110 for aligning a position of a sheet P on the discharging tray 50 in a sheet width direction; an upper surface detection unit 71 for detecting a height of a detection surface at a first detection position at an upstream end of the discharging tray 50 in the sheet discharging direction; and an angle detection sensor 142 for detecting a height of the detection surface at a second detection position downstream of the first detection position in the sheet discharging direction. The alignment mechanism 110 has a pair of alignment members 120, movable in the sheet width direction and a vertical direction, for aligning the sheet P. The angle detection sensor 142 detects the height of the detection surface at the second detection position by detecting the alignment member 120.SELECTED DRAWING: Figure 7

Description

The present invention relates to a sheet discharging device that discharges a sheet such as a paper sheet on which an image is formed by an image forming apparatus such as a copying machine, a facsimile, a printer, a sheet post-processing device including the sheet discharging device, and an image forming system.

Conventionally, a plurality of sheets (sheets) on which images are formed by an image forming apparatus such as a copying machine or a printer are stacked, and a stacking sheet bundle is bound together by staple processing, and a punch hole is formed by a punch hole forming apparatus. A sheet post-processing device capable of performing post-processing such as punch hole forming processing for making (punching) is used.

In such a sheet post-processing apparatus, a sheet ejection port for ejecting a sheet subjected to a predetermined post-processing, an ejection tray on which the sheets ejected from the sheet ejection port are stacked, and a topmost sheet on the ejection tray. A detection sensor that detects a sheet and a tray elevating mechanism that elevates and lowers the discharge tray are provided, and there is also one that is provided with an alignment mechanism that aligns the positions of the sheets stacked on the ejection tray in the width direction. Then, the discharge tray is arranged at a predetermined height position based on the detection result of the detection sensor, so that the height position of the uppermost sheet on the discharge tray becomes substantially constant.

It should be noted that a sheet post-processing apparatus including a discharge tray on which sheets are stacked, a tray elevating mechanism that raises and lowers the discharge tray, and an alignment mechanism that aligns the positions of the sheets stacked on the discharge tray in the width direction is disclosed in, for example, Patent Document 1. 1 is disclosed.

JP, 2014-227278, A

However, in the conventional sheet post-processing apparatus, the detection sensor normally detects the uppermost sheet at the upstream end portion of the discharge tray in the sheet discharge direction. Therefore, if the downstream side of the topmost paper on the output tray is curled, the leading edge of the succeeding paper comes into contact with the curled portion of the paper on the output tray, and the paper already output on the output tray is curled. However, there is a problem in that it causes the extrusion and the misalignment.

The present invention has been made to solve the above problems, and an object of the present invention is to suppress extrusion and misalignment of a sheet due to interference between the already discharged sheet and the leading edge of the succeeding sheet. A sheet discharging device, a sheet post-processing device including the same, and an image forming system.

In order to achieve the above-mentioned object, a sheet discharging device having a first structure of the present invention is a sheet discharging port for discharging a sheet, a discharging member for discharging a sheet from the sheet discharging port, and a sheet discharging port. A discharge tray on which sheets are stacked, a tray elevating mechanism that raises and lowers the discharge tray, an alignment mechanism that aligns the position of the sheets stacked on the discharge tray in the sheet width direction orthogonal to the sheet discharge direction, and the sheet discharge of the discharge tray The first detection position that detects the height of the detection surface with the top surface of the discharge tray or the top surface of the uppermost sheet on the discharge tray as the detection surface at the first detection position at the upstream end in the direction of A second detection unit that detects the height of the detection surface at a second detection position on the downstream side of the sheet discharge direction, and a control unit that controls the discharge member, the tray lifting mechanism, and the alignment mechanism. The aligning mechanism is movable in the sheet width direction and the vertical direction, and has a pair of aligning members that align the sheets by contacting side edges of the sheets in the sheet width direction. The alignment member comes into contact with the detection surface and swings in conjunction with the elevation of the discharge tray. The second detection unit detects the height of the detection surface at the second detection position by detecting the alignment member. The first detection unit and the second detection unit are provided so as to detect the upper surface of the discharge tray when the discharge tray is arranged at the reference position. The control unit lowers the discharge tray every time a predetermined number of sheets are stacked on the discharge tray, and arranges the first detection unit at the first height position where the detection surface is detected. When the detection surface is not detected, the discharge tray is further lowered and placed at the second height position where the second detection unit detects the detection surface.

According to the sheet ejection device of the first configuration of the present invention, the second detection unit is located at the second detection position downstream of the first detection position where the first detection unit detects the height of the detection surface in the sheet ejection direction. Detects the height of the detection surface. Then, the control unit lowers the discharge tray every time when a predetermined number of sheets are stacked on the discharge tray, and arranges the discharge tray at a first height position where the first detection unit detects the detection surface, and then performs the second detection. When the unit does not detect the detection surface, the discharge tray is further lowered and is placed at the second height position where the second detection unit detects the detection surface. Accordingly, even if the downstream side portion of the uppermost sheet on the discharge tray is curled, it is possible to prevent the leading edge of the succeeding sheet from coming into contact with the curled portion of the sheet on the discharge tray. Therefore, it is possible to prevent the sheet discharged onto the discharge tray from being pushed out or misaligned.

FIG. 1 is a schematic diagram showing the configurations of an image forming apparatus and a sheet post-processing apparatus according to an embodiment of the present invention. It is a schematic diagram showing an internal configuration of the upper part of the sheet post-processing apparatus of one embodiment of the present invention. FIG. 3 is a cross-sectional view showing a structure around a sheet discharging device of the sheet post-processing device according to the embodiment of the present invention. FIG. 3 is a perspective view showing a structure around a sheet ejection device of the sheet post-processing device according to the embodiment of the present invention. FIG. 3 is a cross-sectional view showing a structure around a matching member of the sheet post-processing apparatus according to the embodiment of the present invention. FIG. 3 is a perspective view showing a structure around a matching member of the sheet post-processing apparatus according to the embodiment of the present invention. FIG. 4 is a cross-sectional view showing the structure around the sheet ejection device of the sheet post-processing device of one embodiment of the present invention, showing a state in which an alignment member is brought into contact with the upper surface of the sheet without curling. FIG. 3 is a cross-sectional view showing the structure around the sheet ejection device of the sheet post-processing device of one embodiment of the present invention, showing a state in which the downstream side portion of the sheet on the ejection tray is curled. FIG. 6 is a cross-sectional view showing the structure around the sheet ejection device of the sheet post-processing device of one embodiment of the present invention, showing a state in which an alignment member is brought into contact with the upper surface of the curled sheet. FIG. 3 is a perspective view showing a structure around a sheet ejection device of a sheet post-processing apparatus according to an embodiment of the present invention, showing a state in which an alignment member is brought into contact with the upper surface of the curled sheet.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First, an image forming system including an image forming apparatus 100 and a sheet post-processing apparatus 20 according to an embodiment of the present invention will be described with reference to FIG. In the present embodiment, a multifunction peripheral is illustrated as an example of the image forming apparatus 100, but the sheet post-processing device 20 of the present invention may be used in a laser printer, an inkjet printer, a facsimile machine, etc. other than the digital multifunction peripheral. Can be similarly connected.

As shown in FIG. 1, the image forming apparatus 100 is a so-called in-body discharge type digital multi-function peripheral, and an image reading unit 8 for reading an image of an original as an electric signal is provided on an upper portion of the main body of the image forming apparatus 100. The document feeder 3 is attached to the above-mentioned document feeder. A sheet post-processing device (sheet post-processing device) 20 is connected to the left side of the main body of the image forming apparatus 100.

The main body of the image forming apparatus 100 includes an image forming unit that forms a toner image on a sheet (sheet), a fixing device that fixes the toner image on the sheet, and the sheet after the fixing is conveyed to the main body of the image forming apparatus 100. A sheet discharging unit for discharging, a main body control unit 80, and the like are provided. The main body control unit 80 controls the operation of the image forming apparatus 100, and is configured to be communicable with the post-processing control unit 81 of the sheet post-processing device 20 and controls the post-processing control unit 81. The post-processing control unit 81 is an example of the “control unit” in the present invention.

As shown in FIG. 2, inside the sheet post-processing device 20, a punch hole forming device 21 for forming punch holes on a conveyed sheet P (see FIG. 3), and a plurality of conveyed sheets P are stacked ( A stacking processing tray 30 and a stapler (stapling device) 40 that staples a bundle of sheets stacked on the processing tray 30 are provided. On the side surface of the sheet post-processing device 20, a discharge tray 50 that can be raised and lowered to a position suitable for discharging the sheet P is provided.

The punch hole forming device 21 is arranged above the sheet post-processing device 20, and forms a plurality of punch holes along one side edge (front side or rear side of the apparatus) parallel to the conveyance direction of the sheet P. .. The punch hole forming device 21 may be one that forms a plurality of punch holes along the side edge in the direction orthogonal to the conveyance direction of the paper P. A paper P that is carried into the paper post-processing device 20 from the image forming apparatus 100 is located at a substantially central portion on the upstream side of the punch hole forming device 21 and in the direction orthogonal to the paper conveyance direction (direction perpendicular to the paper surface of FIG. 2). A carry-in detection sensor (not shown) for detecting the tip of the sheet is disposed.

Above the discharge tray 50, an upper tray 55 is mainly provided for discharging the paper P that is not bound. Below the sheet post-processing device 20, a sheet folding unit (not shown) for folding the sheet P is provided.

FIG. 3 is a cross-sectional view showing the structure around the sheet ejection device 150 of the sheet post-processing device 20 according to the embodiment of the present invention. An intermediate roller pair 27 is disposed on the downstream side of the punch hole forming device 21 (see FIG. 1) with respect to the sheet conveying direction. An actuator-type sheet detection sensor (not shown) that detects passage of the sheet P is arranged upstream of the intermediate roller pair 27.

Further, below the intermediate roller pair 27, there are a processing tray 30 for stacking a predetermined number of sheets P conveyed by the intermediate roller pair 27 in an aligned manner, and a bundle of sheets P stacked on the processing tray 30 (sheet bundle). A stapler 40 (see FIG. 2) that performs a binding process is provided.

A sheet discharge port (sheet discharge port) 22 is provided on the downstream side (left side in FIG. 3) of the processing tray 30 with respect to the sheet discharge direction, and the sheet P is discharged to the discharge tray 50 through the sheet discharge port 22. A discharge roller pair (discharge member) 29 is disposed. A plurality of (two here) discharge rollers 29 are provided along the paper width direction (the direction perpendicular to the paper surface of FIG. 3 and the direction orthogonal to the paper conveyance direction). Further, the discharge roller pair 29 receives a rotational drive force from a drive motor (not shown) via the intermediate gear 28a, the transmission belt 28b, and the like, and has a lower discharge roller 29a made of rubber that can rotate forward and backward, and a drive motor. And an upper discharge roller 29b capable of rotating in the normal and reverse directions, to which a rotational driving force is transmitted via an intermediate gear or the like (both not shown).

The upper discharge roller 29b is supported by a roller holder 31 which can swing up and down about a pivot shaft 31a, and the lower discharge roller 29a and the upper discharge roller 29b can come into contact with and separate from each other. The roller holder 31 is swung by a holder driving mechanism 36 including, for example, a stepping motor and a gear, a motor, a gear, a cam, and the like. The holder drive mechanism 36 is controlled by the post-processing control unit 81 (see FIG. 1).

The upper discharge roller 29b is moved by the holder driving mechanism 36 to form a nip portion by contacting the lower discharge roller 29a to form a nip portion (position in FIG. 3) and a separated position (upwardly illustrated) separated from the upper discharge roller 29b. )), and is placed selectively.

To the upper side of the processing tray 30 and on the downstream side of the intermediate roller pair 27 (left side in FIG. 3 ), the paper P carried in by the intermediate roller pair 27 is hit in the processing tray 30 direction, and the tray surface (the upper surface of the processing tray 30. ), a hitting member (not shown) is provided. The intermediate roller pair 27 is composed of a lower roller 27b that is rotatable by a drive motor (not shown) and an upper roller 27a that is rotated by being driven by the lower roller 27b. Below the lower roller 27b, a roller holder 33 that can be swung about the rotation axis of the lower roller 27b as a fulcrum, and rotatably supported by the roller holder 33 and rotatable by a rotational driving force from a drive motor (not shown). A retractable roller 32 is provided. A pair of pull-in rollers 32 are provided along the paper width direction.

The processing tray 30 is provided so as to incline downward toward the rear end (upstream end in the paper ejection direction) side (right side in FIG. 3) of the stacked paper P, and the pull-in roller 32 rotates the lower roller 27b. By rotating counterclockwise in FIG. 3 while swinging downward about the axis as a fulcrum, the paper P is drawn onto the processing tray 30 from the upstream end (rear end) side and the upstream end of the paper P is projected. It contacts the contact part 30a. As a result, the sheets P are stacked on the processing tray 30 with their upstream ends aligned. Further, the processing tray 30 is provided with a pair of side edge alignment cursors 35 for aligning a predetermined number of sheets stacked on the processing tray 30 in the sheet width direction orthogonal to the sheet transport direction.

The stapler 40 (see FIG. 1) can be moved in the paper width direction by a moving mechanism (not shown), and moves to a predetermined position along the lower end of the processing tray 30 according to the content of the binding process.

Next, the operation of the sheet post-processing device 20 will be described. When the sheet P that has been subjected to the image forming processing by the image forming apparatus 100 is carried in, and if punch hole formation is instructed, a predetermined position of the sheet P conveyed by the punch hole forming apparatus 21 (for example, on the front side of the apparatus). Punch holes are formed at two positions along the side edge), and when the punch hole formation is not instructed, the punch hole forming device 21 is directly passed.

Then, the sheet P is conveyed further downstream by the intermediate roller pair 27.

When the binding process on the processing tray 30 is not instructed, the paper P that has passed through the punch hole forming device 21 is discharged to the discharge tray 50 as it is by the intermediate roller pair 27 and the discharge roller pair 29, as shown in FIG. To be done. At this time, the roller holder 31 is swinging downward, and the upper discharge roller 29b is arranged at the nip forming position where it contacts the lower discharge roller 29a.

On the other hand, when the binding process on the processing tray 30 is instructed, the hitting member (not shown) is driven at the timing when the rear end of the paper P passes through the intermediate roller pair 27 to drive the paper P to the processing tray 30. Follow. At this time, the roller holder 31 is swinging upward, and the upper discharge roller 29b is arranged at a position separated from the lower discharge roller 29a (separated position). When the roller holder 31 swings downward, the upper discharge roller 29b nips the sheet P with the lower discharge roller 29a and rotates in the counterclockwise direction in FIG. At this time, the rotation of the lower discharge roller 29a is stopped. When the trailing edge of the sheet P is nipped by the pull-in roller 32, the roller holder 31 swings upward, and the upper discharge roller 29b is separated from the sheet P.

In this state, the drawing roller 32 is rotated in the normal direction (counterclockwise in FIG. 3) so that the sheet P is drawn along the processing tray 30 and the trailing edge is aligned by the abutting portion 30a. The abutting portion 30a is not formed continuously over the entire area in the sheet width direction, but a notch is partially formed. At this time, the leading edge of the paper P is discharged onto the discharge tray 50.

When the receipt of one bundle (predetermined number) of sheets P is completed, the stapler 40 is moved to the notch position of the abutting portion 30a, and the binding process of the rear end of the sheet bundle is performed.

Then, the roller holder 31 is swung downward to move the upper discharge roller 29b to the nip forming position. After that, the sheet bundle is conveyed upward along the processing tray 30 by rotating the lower discharge roller 29a in the forward direction (counterclockwise rotation in FIG. 3) and discharged onto the discharge tray 50. When the sheet bundle on the processing tray 30 is discharged, a discharge member (not shown) that comes into contact with the upstream end of the sheet bundle and moves toward the sheet discharge port 22 along the upper surface of the processing tray 30 is provided. The sheet bundle may be discharged by a discharge member (not shown) and the discharge roller pair 29.

Next, the structure around the discharge tray 50 will be described in detail.

The sheet post-processing device 20 includes a tray elevating mechanism 70 that elevates and lowers the discharge tray 50, and a top sheet stacked on the discharge tray 50 at a first detection position at an upstream end of the discharge tray 50 in the sheet discharge direction. The upper surface of P (the sheet mounting surface (sheet mounting surface) 51 of the discharge tray 50 when the paper P is not mounted) is used as the detection surface, and the upper surface detection unit (first And a detector 71) are provided. Note that the paper ejection device (sheet ejection device) 150 is configured by the paper ejection port 22, the ejection roller pair 29, the ejection tray 50, the tray lifting mechanism 70, the upper surface detection unit 71, the post-processing control unit 81, the alignment mechanism 110 described later, and the like. Is configured.

The tray lifting mechanism 70 is composed of, for example, a drive motor, a pinion gear, a rack, and the like.

The upper surface detection unit 71 is composed of a PI sensor having a light emitting unit and a light receiving unit, and sends the detection result to the post-processing control unit 81 (see FIG. 1). The light emitting unit and the light receiving unit of the upper surface detecting unit 71 are arranged on both sides in the paper width direction with the discharge tray 50 sandwiched therebetween, and the light emitted from the light emitting unit is shielded by the paper P so that the uppermost paper is placed. Detect P.

The post-processing control unit 81 (see FIG. 1) includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and controls the entire sheet post-processing apparatus 20. In addition, the post-processing control unit 81 includes information about the paper P (paper size, type of the paper P (material and thickness of the paper P)) input by the user on the operation unit (not shown) of the image forming apparatus 100, and one bundle. (For example, the number of sheets of paper P) is received via the receiving unit (acquiring unit) 82 (see FIG. 1) provided in the post-processing device 20.

Further, the sheet post-processing device 20 is provided with an alignment mechanism 110 that aligns the positions of the sheets P stacked on the discharge tray 50 in the width direction. As shown in FIGS. 3 and 4, the aligning mechanism 110 is movable in the paper width direction and the vertical direction, and a pair of aligning devices for aligning the paper P in the width direction by abutting the side edges of the paper P in the width direction. The member 120, the width-direction moving mechanism 111 (see FIG. 5) that moves the aligning member 120 in the paper width direction, the up-down direction moving mechanism 112 that moves the aligning member 120 in the up-down direction, and the light-shielding member 134, which will be described later, the angle. It has a detection sensor 142 and the like.

Here, in this embodiment, the aligning member 120 is configured to align the paper P on the discharge tray 50 in the width direction and detect the height of the uppermost paper P.

Specifically, recesses 52 into which the lower end of the aligning member 120 can enter are provided on both sides of the upper surface of the discharge tray 50 in the paper width direction. The aligning member 120 aligns the sheet P by moving in the sheet width direction with the lower end portion entering the recess 52 (projecting below the sheet placement surface 51).

As shown in FIG. 4, the alignment member 120 is held by the lower portion of the carriage 122 (hereinafter referred to as the holding portion 122a). As shown in FIG. 5, a rotating shaft 124 is provided inside the holding portion 122 a, and the matching member 120 is rotatably supported by the rotating shaft 124. The alignment member 120 is integrally formed with a gear portion 120a that is rotatably supported by the rotating shaft 124.

The carriage 122 is moved in the paper width direction by the width direction moving mechanism 111 along a guide shaft 126 and a drive shaft 128 extending in the paper width direction. The width direction moving mechanism 111 may be configured by, for example, an endless moving belt to which the carriage 122 is attached and extends in the paper width direction, a pulley around which the moving belt is wound, a drive motor that rotationally drives the pulley, and the like. However, it may be configured by a rack extending in the paper width direction, a pinion provided on the carriage 122 and engaging with the rack, a drive motor for rotationally driving the pinion, and the like.

As shown in FIG. 6, the input gear 132 and the light blocking member 134 are fixed to one end (the left end in FIG. 6) of the drive shaft 128. The input gear 132 is connected to the pulse motor 136 via a one-way member (not shown) including a one-way gear that transmits rotation only in one direction. Further, near the one end of the drive shaft 128, an angle detection sensor (second detection unit) 142 including a PI sensor having a light emitting unit and a light receiving unit is provided. The angle detection sensor 142 detects opening or blocking of the optical path by the light blocking piece 134a of the light blocking member 134, and transmits the detection result to the post-processing control unit 81. As will be described later, the angle detection sensor 142 detects that the aligning member 120 is the upper surface of the uppermost sheet P on the discharge tray 50 (or the sheet mounting surface of the discharge tray 50 (the sheet mounting surface when the sheet P is not mounted). The height of the detection surface is detected by abutting against the detection surface (mounting surface) 51). As will be described later, the angle detecting sensor 142 and the light blocking piece 134a open the optical path of the angle detecting sensor 142 when the downstream side portion of the paper P on the discharge tray 50 is curled even a little. It is provided at the position where That is, the upper surface detection unit 71 and the angle detection sensor 142 are provided so as to detect (turn on) the upper surface of the discharge tray 50 when the discharge tray 50 is arranged at the reference position.

The drive shaft 128 is formed in a D cut shape. The carriage 122 has a bearing portion 122b into which the drive shaft 128 is inserted. Since the bearing portion 122b is formed in a circular shape in cross section, the drive shaft 128 idles with respect to the bearing portion 122b.

As shown in FIG. 5, inside the carriage 122, a gear 138 that is slidable in the axial direction with respect to the drive shaft 128 and rotates integrally with the drive shaft 128, and a gear portion of the alignment member 120 that rotates the gear 138. The intermediate gear 140 which transmits to 120a is provided. The carriage 122, the intermediate gear 140, the gear 138, the drive shaft 128, the input gear 132, the pulse motor 136, a one-way member (not shown), and the like constitute the vertical movement mechanism 112.

When the pulse motor 136 (see FIG. 6) rotates in the forward direction, the alignment member 120 rotates in the forward direction around the drive shaft 128 (rotates in the clockwise direction in FIG. 3), and the tip of the alignment member 120 is lifted. At this time, after the light-shielding piece 134a of the light-shielding member 134 opens the optical path of the angle detection sensor 142, the pulse motor 136 is further rotated by a predetermined pulse and stopped, so that the alignment member 120 is removed from the paper P on the discharge tray 50. It is placed at the retracted position (the position above FIG. 9).

When the pulse motor 136 reversely rotates from this state, the matching member 120 reversely rotates (rotates counterclockwise in FIG. 3) due to its own weight, and the leading end of the matching member 120 moves downward. At this time, when the aligning member 120 is arranged at a position where the aligning member 120 does not come into contact with the paper P on the discharge tray 50 (a position on the outer side in the paper width direction with respect to the paper stacking area), the lower end of the aligning member 120 is located in the recess 52. After entering, the aligning member 120 is arranged at the aligning position (position in FIGS. 3 and 4) where the sheet P can be aligned. When the aligning member 120 is arranged at a position where it comes into contact with the paper P on the discharge tray 50 (position on the inner side in the paper width direction with respect to the paper stacking area), as shown in FIG. The portion contacts the paper P, and the downward movement (counterclockwise rotation) of the alignment member 120 is stopped by the action of a one-way member (not shown) between the pulse motor 136 and the input gear 132. At this time, the alignment member 120 has the highest position at the second detection position downstream of the first detection position where the upper surface detection unit 71 detects the height of the uppermost paper P on the discharge tray 50, in the paper discharge direction. The upper surface of the paper P.

Here, as shown in FIG. 8, when the uppermost paper P on the discharge tray 50 is curled at the downstream side in the paper discharge direction, the succeeding paper P (the discharge roller pair 29 discharges the paper P). The leading edge of the sheet P) may come into contact with the curled portion of the uppermost sheet P. In this case, the paper P on the discharge tray 50 is pushed out or misalignment occurs.

Therefore, in the present embodiment, when the uppermost sheet P on the discharge tray 50 is curled on the downstream side in the sheet discharge direction, the leading edge of the succeeding sheet P is the uppermost sheet on the discharge tray 50. The discharge tray 50 is lowered by a predetermined amount so that it is hard to contact the curled portion of the paper P. That is, the post-processing control unit 81 compares the height detection result by the angle detection sensor 142 using the alignment member 120 with the height detection result by the upper surface detection unit 71. When the height detection result of the angle detection sensor 142 is lower than the height detection result of the upper surface detection unit 71, the post-processing control unit 81 places the discharge tray 50 at the first height position. When the sheet P is discharged to the discharge tray 50 by the, and the height detection result by the angle detection sensor 142 is higher than the height detection result by the upper surface detection unit 71, the discharge tray 50 is set to the second height lower than the first height position. The paper P is discharged to the discharge tray 50 in the state of being arranged at the height position of. In other words, when the height detection result by the angle detection sensor 142 is higher than the height detection result by the upper surface detection unit 71, the post-processing control unit 81 determines that the height detection result by the angle detection sensor 142 is higher than the height detection result by the upper surface detection unit 71. The paper P is discharged to the discharge tray 50 in a state where the discharge tray 50 is lowered as compared with the case where the height is less than the result of the detection.

Specifically, every time a predetermined number of sheets of paper P are discharged onto the discharge tray 50 by the discharge roller pair 29 (every first timing when the number of stacked sheets of paper P on the discharge tray 50 increases by the first stacked number). The discharge tray 50 is lowered until the uppermost sheet P on the discharge tray 50 is detected by the upper surface detection unit 71 (until the upper surface detection unit is switched on). At this time, the discharge tray 50 is lowered from the reference position to a position where the upper surface detection unit 71 is once switched off, and then is raised to a position where the upper surface detection unit 71 is switched on and stopped, and a first elevating operation is performed. At this time, the height of the uppermost sheet P at the upstream end of the discharge tray 50 from the floor surface is constant.

Then, the alignment member 120 is moved to a position inside the sheet stacking area in the sheet width direction in a state where the aligning member 120 is rotated to the retracted position (position above FIG. 9). After that, by rotating the pulse motor 136 in the reverse direction, the aligning member 120 rotates counterclockwise in FIG. 7 due to its own weight, and contacts the upper surface of the uppermost sheet P.

At this time, when the paper P is not curled (in the case of FIG. 7, the paper P is parallel to the paper placement surface 51) or when the upstream end of the paper P is curled, the light is blocked. The piece 134a blocks the optical path of the angle detection sensor 142, and the angle detection sensor 142 detects the light blocking piece 134a. Then, the succeeding paper P is discharged onto the discharge tray 50 arranged at the first height position (the height position where the upper surface detection unit 71 detects the detection surface).

On the other hand, when the downstream portion of the paper P (the position where the alignment member 120 abuts) is curled even a little (in the case of FIGS. 9 and 10), the light blocking piece 134a opens the optical path of the angle detection sensor 142. The angle detection sensor 142 does not detect the light shielding piece 134a (it is OFF). In this case, the second raising/lowering operation is performed in which the discharge tray 50 is lowered to the position where the angle detection sensor 142 detects the light blocking piece 134a (the position where it is switched on) and stopped. That is, the discharge tray 50 is lowered by the difference between the height detection result of the angle detection sensor 142 and the height detection result of the upper surface detection unit 71. Then, the succeeding paper P is discharged onto the discharge tray 50 arranged at the second height position (the height position where the angle detection sensor 142 detects the detection surface).

Note that the height detection of the paper P by the upper surface detection unit 71 and the height detection of the paper P by the angle detection sensor 142 are, for example, 10 to 20 when the papers P are discharged one by one onto the discharge tray 50. This is executed every time the first sheet number is ejected, and when the sheet bundle is ejected onto the ejection tray 50, for example, it is executed every time the sheet bundle is ejected. In addition, when the sheets P are discharged one by one onto the discharge tray 50, the alignment of the sheets P in the width direction by the aligning member 120 is executed every time one sheet P is discharged, and the sheet bundle is discharged onto the discharge tray 50. If it is discharged, it is not executed.

In the present embodiment, as described above, at the second detection position downstream of the first detection position where the upper surface detection unit 71 detects the height of the upper surface (detection surface) of the uppermost sheet P in the paper discharge direction. The angle detection sensor 142 detects the height of the upper surface (detection surface) of the uppermost sheet P. Whenever the angle detection sensor 142 does not detect the detection surface after the discharge tray 50 is lowered to the first height position every time the predetermined number of sheets P are stacked on the discharge tray 50, the discharge tray 50 is removed. It is further lowered and placed at the second height position. As a result, even if the downstream side portion of the uppermost sheet P on the discharge tray 50 is curled, the leading edge of the succeeding sheet P contacts the curled portion of the sheet P on the discharge tray 50. Therefore, it is possible to prevent the ejection of the sheet P ejected onto the ejection tray 50 and the occurrence of misalignment.

Further, as described above, when the height detection result of the angle detection sensor 142 is higher than the height detection result of the upper surface detection unit 71 (for example, in the case of FIG. 9), the post-processing control unit 81 uses the angle detection sensor 142. Compared with the case where the height detection result is lower than the height detection result by the upper surface detection unit 71 (for example, in the case of FIG. 7), the height detection result by the angle detection sensor 142 and the height detection by the upper surface detection unit 71. The paper P is discharged onto the discharge tray 50 with the discharge tray 50 being lowered by the difference from the result. As a result, when the height detection result of the angle detection sensor 142 is higher than the height detection result of the upper surface detection unit 71, the leading edge of the succeeding paper P may come into contact with the curled portion of the paper P on the discharge tray 50. While suppressing, it is possible to prevent the height position of the discharge tray 50 from becoming too low. That is, the discharge tray 50 can be easily arranged at an appropriate height position.

Further, as described above, the alignment member 120 is provided so as to be vertically rotatable about the rotary shaft 124 extending in the paper width direction, and the light blocking piece 134a is interlocked with the rotation of the alignment member 120. Rotate. Accordingly, since the rotation angle of the angle detection sensor 142 can be easily detected, the height of the uppermost sheet P on the discharge tray 50 can be easily detected.

Further, as described above, every time two or more first sheets (here, 10 to 20 sheets) of paper P are discharged to the discharge tray 50, the uppermost surface is detected by the upper surface detection unit 71 and the angle detection sensor 142. The height of the paper P is detected. As a result, it is possible to more reliably prevent the ejection of the paper P discharged onto the discharge tray 50 and the occurrence of misalignment.

It should be considered that the embodiments disclosed this time are exemplifications in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and includes meanings equivalent to the scope of claims for patent and all modifications within the scope.

For example, in the above embodiment, the example in which the sheet ejection device 150 is provided in the sheet post-processing device 20 has been described, but the present invention is not limited to this, and the sheet ejection device may be provided in the image forming apparatus.

Further, in the above-described embodiment, an example in which the alignment member 120 is moved in the vertical direction by rotation is shown, but the present invention is not limited to this, and the alignment member 120 may be translated in the vertical direction.

Further, in the above embodiment, an example in which the rotation angle of the matching member 120 is detected in one step (whether it is a certain angle or more) using the angle detection sensor 142 and the light shielding piece 134a has been shown, but the present invention is not limited to this. Not limited to this, the rotation angle of the alignment member 120 may be detected in multiple stages. In this case, for example, a plurality of slits may be provided in the light shielding piece 134a at regular angular intervals, and the rotation angle of the matching member 120 may be detected in multiple stages based on the output pulse signal. Further, for example, a plurality of angle detection sensors 142 may be provided.

Further, in the above-described embodiment, every time the first number of sheets P (here, 10 to 20 sheets) of paper P are ejected to the ejection tray 50, the uppermost paper P is detected by the upper surface detection unit 71 and the angle detection sensor 142. Although the example of detecting the height is shown, the present invention is not limited to this. For example, the upper surface detection unit 71 outputs the first number of sheets P (here, 10 to 20 sheets) to the discharge tray 50 (the number of sheets P stacked on the discharge tray 50 is the first number of stacked sheets). The height of the uppermost sheet P is detected (every first timing that increases only), and the angle detection sensor 142 causes the discharge tray 50 to output a second number (eg, 2) that is an integer multiple of 2 or more of the first number. The height of the uppermost paper P is detected every time the paper P of several hundred sheets is discharged (every second timing when the number of the paper P stacked on the discharge tray 50 is increased by the second stack number). Good. With this configuration, for example, compared with the case where the height of the uppermost sheet P is detected by the upper surface detection unit 71 and the angle detection sensor 142 each time the first number of sheets P of paper are discharged to the discharge tray 50. As a result, it is possible to shorten the time required to discharge the paper P.

Further, configurations obtained by appropriately combining the configurations of the above-described embodiments and modified examples are also included in the technical scope of the present invention.

20 Paper post-processing device (sheet post-processing device)
22 Paper outlet (sheet outlet)
29 Ejection roller pair (ejection member)
30 processing tray 40 stapler (stapling device)
50 Ejection Tray 70 Tray Elevating Mechanism 71 Upper Surface Detection Section (First Detection Section)
81 Post-processing control unit (control unit)
100 Image Forming Apparatus 110 Alignment Mechanism 111 Width Direction Movement Mechanism 112 Vertical Direction Movement Mechanism 120 Alignment Member 124 Rotation Shaft 134a Light Shielding Piece 142 Angle Detection Sensor (Second Detection Section)
150 Paper ejection device (sheet ejection device)
P paper (sheet)

Claims (9)

A sheet discharge port for discharging sheets,
A discharge member for discharging the sheet from the sheet discharge port,
A discharge tray on which the sheets discharged from the sheet discharge port are stacked,
A tray elevating mechanism for elevating the discharge tray,
An alignment mechanism for aligning the position of the sheets stacked on the discharge tray in the sheet width direction orthogonal to the sheet discharge direction,
At the first detection position at the upstream end of the discharge tray in the sheet discharge direction, the height of the detection surface is detected using the upper surface of the discharge tray or the uppermost sheet of the discharge tray as the detection surface. A first detector,
A second detection unit that detects the height of the detection surface at a second detection position downstream of the first detection position in the sheet discharge direction;
A control unit that controls the discharge member, the tray lifting mechanism, and the alignment mechanism;
Equipped with
The matching mechanism is
A pair of aligning members that are movable in the sheet width direction and the up-down direction, align the sheets by contacting side edges of the sheet in the sheet width direction,
The alignment member is in contact with the detection surface and swings in conjunction with the elevation of the discharge tray,
The second detection unit detects the height of the detection surface at the second detection position by detecting the alignment member,
The first detection unit and the second detection unit are provided to detect the upper surface of the discharge tray when the discharge tray is arranged at the reference position,
The control unit lowers the discharge tray every time when a predetermined number of sheets are stacked on the discharge tray, and arranges the first detection unit at a first height position where the detection surface is detected, When the second detection unit does not detect the detection surface, the discharge tray is further lowered, and the second detection unit is arranged at a second height position where the detection surface is detected. Ejection device. When the height detection result by the second detection unit is higher than the height detection result by the first detection unit, the control unit determines that the height detection result by the second detection unit is the height by the first detection unit. Compared to the case where the height is less than the detection result, the discharge tray is lowered in the state where the discharge tray is lowered by the difference between the height detection result by the second detection unit and the height detection result by the first detection unit. The sheet ejection device according to claim 1, wherein the sheet is ejected to a tray. The alignment member is provided so as to be vertically rotatable about a rotation shaft extending in the sheet width direction,
The sheet ejection device according to claim 1, wherein the light blocking piece rotates in conjunction with rotation of the alignment member. The first detection unit and the second detection unit detect the height of the uppermost sheet every time when two or more first sheets are discharged to the discharge tray. The sheet discharging device according to claim 1. The first detection unit detects the height of the uppermost sheet every time two or more first sheets of the sheets are discharged to the discharge tray,
The second detection unit may detect the height of the uppermost sheet every time a second number of sheets, which is an integer multiple of 2 or more of the first number, is discharged to the discharge tray. The sheet ejection device according to claim 1, wherein the sheet ejection device is a sheet ejection device. A sheet discharging device according to any one of claims 1 to 5,
A processing tray on which the sheets are stacked,
A stapling device for binding the sheets on the processing tray;
A sheet post-processing apparatus comprising: An image forming apparatus that is connected to the sheet post-processing apparatus according to claim 6, forms an image on the sheet, and conveys the sheet on which the image is formed to the sheet post-processing apparatus,
An image forming system comprising: A sheet discharge port for discharging sheets,
A discharge member for discharging the sheet from the sheet discharge port,
A discharge tray on which the sheets discharged from the sheet discharge port are stacked,
A tray elevating mechanism for elevating the discharge tray,
At the first detection position at the upstream end of the discharge tray in the sheet discharge direction, the height of the detection surface is detected using the upper surface of the discharge tray or the uppermost sheet of the discharge tray as the detection surface. A first detector,
A second detection unit that detects the height of the detection surface at a second detection position downstream of the first detection position in the sheet discharge direction;
A control unit for controlling the tray lifting mechanism,
Equipped with
The first detection unit and the second detection unit are provided to detect the upper surface of the discharge tray when the discharge tray is arranged at the reference position,
The control unit lowers the discharge tray every time when a predetermined number of sheets are stacked on the discharge tray, and arranges the first detection unit at a first height position where the detection surface is detected, When the second detection unit does not detect the detection surface, the discharge tray is further lowered, and the second detection unit is arranged at a second height position where the detection surface is detected. Ejection device. A sheet discharge port for discharging sheets,
A discharge member for discharging the sheet from the sheet discharge port,
A discharge tray on which the sheets discharged from the sheet discharge port are stacked,
A tray elevating mechanism for elevating the discharge tray,
At the first detection position at the upstream end of the discharge tray in the sheet discharge direction, the height of the detection surface is detected using the upper surface of the discharge tray or the uppermost sheet of the discharge tray as the detection surface. A first detector,
A second detection unit that detects the height of the detection surface at a second detection position downstream of the first detection position in the sheet discharge direction;
A control unit for controlling the tray lifting mechanism,
Equipped with
The first detection unit and the second detection unit are provided so as to be turned on when the discharge tray is arranged at the reference position,
The control unit is
The discharge tray is lowered from the reference position to a position where the first detection unit is once switched off at each first timing when the number of stacked sheets on the discharge tray increases by a predetermined first stacked number. After that, the first elevating operation is performed in which the detecting unit is raised to a position where it is turned on and stopped.
The first detection unit and the first detection unit after the first elevating operation are repeated at every second timing when the first elevating operation is repeated and the number of sheets stacked on the discharge tray increases by a predetermined second sheet number. Comparing the detection results of the two detection units, and when the first detection unit is ON and the second detection unit is OFF, the discharge tray is lowered to the position where the second detection unit is switched to the second position and stopped. A sheet ejection device, which performs a lifting operation.

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