JP2007076903A - Paper loading device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and economical paper loading device capable of reducing influence on image by a paper returning member. <P>SOLUTION: This paper loading device is provided with a tray 4 for loading a paper to be loaded, a tray shift means for shifting and moving the tray 4 in the direction crossing the direction of delivery orthogonally, the paper returning member 3 for returning the paper delivered on the tray 4 onto the upstream side in the direction of delivery to align rear ends of papers, a moving means for moving the paper returning member 3 to a predetermined position, and a tray control means for controlling each part including the moving means. The tray control means moves a contact position of the paper returning member 3 with a paper in accordance with a delivery condition of the paper by the moving means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a paper stacking device that is mounted on an image forming apparatus such as a copying machine, a laser printer, a facsimile machine, a printing machine, or a paper post-processing device and performs shift sorting.

  2. Description of the Related Art Conventionally, a so-called paper stacking device is known that stacks paper on which an image is formed by a copying machine or the like for each job and stacks it. In such an apparatus, there is a sorter type in which a plurality of paper discharge trays (bins) are provided. However, a mechanism that shifts the paper back and forth in the horizontal direction on the paper discharge tray is generally employed. Such a mechanism is described herein as a shift tray. Such a shift tray is normally capable of stacking 1000 to 2000 sheets in A4 size, and a drive motor used for the tray shift is a DC motor that is small and inexpensive and can obtain a large torque.

  Conventionally, shift trays generally have two tray stop positions before and after the front end stop position and the rear end stop position of the tray shiftable width because of simplification of the mechanism and ease of control. In this case, the shift amount of the sheet is set to about 30 mm so that the sheet can be easily identified.

  By the way, in such a paper stacking apparatus having a paper discharge tray, an aligning device for aligning the discharged paper is provided, and a device for moving the position of the return member to a return position that contacts the discharged paper and a standby position that does not contact the discharged paper (For example, refer to Patent Documents 1 and 2).

JP 2003-2524 A JP 2002-167104 A

  However, in the conventional technique as described above, if the return member is kept in contact with the same portion, image smearing or image scraping occurs. On the other hand, in order to avoid this, if the return member is placed on standby and is not in contact, the stackability of the stacked sheets deteriorates, for example, the stacked sheet bundle collapses. That is, when the tray is shifted, if the return member is not brought into contact, the loaded paper is broken due to the momentum of the shifting operation and the stacking property is deteriorated. In particular, in a high-speed machine, there is a case where a tray shift is performed while discharging paper in order to suppress a decrease in productivity at the time of tray shift. At this time, if the return member is not in contact with the stacked paper, Since the end face and the end face of the discharged paper come into contact with each other, the paper is displaced and the stackability is deteriorated. In this way, a return member is required to align the discharged paper, but on the other hand, in terms of the influence on the image, the enlargement of the apparatus by separately providing a discharge paper aligning device, and economical efficiency There was a problem.

  The present invention has been made in view of the above, and an object of the present invention is to provide a small and economical paper stacking device that reduces the influence of the paper returning member on the image.

  In order to solve the above-described problems and achieve the object, the invention according to claim 1 is a discharge tray on which sheets to be stacked are stacked, and a direction in which the discharge tray is orthogonal to the discharge direction of the sheets. A tray shift means for shifting the sheet to the sheet discharge position, a sheet return means for returning the sheet discharged onto the discharge tray to the upstream side in the discharge direction and aligning the trailing edge of the sheet, and a movement for moving the sheet return means to a predetermined position. And a tray control means for controlling each part including the moving means, wherein the tray control means determines the contact position of the paper return means to the paper according to the paper discharge state by the moving means. It is characterized by moving.

  According to the first aspect of the present invention, the contact position of the paper returning means to the paper is moved by the moving means according to the discharge state of the paper, so that the deterioration of the stacking property is avoided, and the paper returning means is placed at the same location. By moving the contact position instead of keeping touching the image, it is possible to reduce the occurrence of image smearing or image shaving.

  The invention according to claim 2 is characterized in that the paper returning means is driven by the same drive source as the means for conveying the paper.

  According to the second aspect of the invention, in the first aspect, the sheet returning means is driven by the same drive source as the means for conveying the paper, so that the apparatus can be downsized and the cost can be reduced. .

  According to a third aspect of the present invention, at least two positions of the sheet return means are provided, that is, a sheet return position and a sheet holding position, and the sheet holding position is disposed upstream of the sheet return position. Features.

  According to the third aspect of the present invention, in the first or second aspect, by providing at least two positions of the paper return means, that is, the paper return position and the paper holding position, the paper return means is brought into contact with the paper at the same place. Further, by disposing the paper holding position on the upstream side of the paper return position, the paper return means is brought into contact with the paper end surface side where there is no more image, so that the image is smudged or image scraped. It becomes possible to reduce the degree of.

  The invention according to claim 4 is characterized in that the position of the sheet return means when the sheet is discharged to the sheet discharge tray is the sheet holding position.

  According to the fourth aspect of the invention, in the third aspect, when the paper is discharged to the paper discharge tray, the paper return means is set to the paper holding position so that the rear end of the paper is discharged. Therefore, it is possible to avoid the deterioration of the stacking property that occurs when the trailing edge of the discharged paper is placed on the paper returning means and is ejected to the downstream side where the paper returning means does not reach.

  Further, the invention according to claim 5 is characterized in that the sheet returning means is moved to a position in contact with the sheet on the rear end side of the sheet after aligning the sheet discharged to the sheet discharge tray.

  According to the fifth aspect of the present invention, in the third or fourth aspect, the sheet return means is moved to a sheet holding position that is in contact with a sheet that is unlikely to have an image at the rear end of the sheet as much as possible. It is possible to suppress the occurrence of image contamination, image shaving, etc. while securing the image quality.

  The invention according to claim 6 is characterized in that the tray control means sets the paper return means to the paper holding position when the discharge tray is shifted.

  According to the sixth aspect of the present invention, in the third, fourth, or fifth aspect, there is a possibility that an image at the rear end of the sheet exists by setting the position of the sheet returning means to the sheet holding position when the discharge tray is shifted. It is possible to suppress the occurrence of image smearing, image scraping, and the like by moving to a paper holding position that comes into contact with a low-quality paper.

  The invention according to claim 7 further includes a sheet detection unit that detects a conveyance state of the sheet, and the tray control unit determines a sheet discharge state and an alignment state according to a detection result of the sheet detection unit. The sheet returning means is moved.

  According to the seventh aspect of the present invention, in any one of the third to sixth aspects, the paper discharge state and the alignment state are determined according to the detection result of the paper detection means arranged in the paper conveyance path. It is possible to determine the movement timing of the sheet returning means without providing a simple sheet state detecting means.

  The paper stacking apparatus according to the present invention (aspect 1) avoids deterioration of stackability by moving the contact position of the paper return means to the paper according to the discharge state of the paper, and prevents paper return. By moving the contact position instead of keeping the means in contact with each other at the same location, it is possible to reduce the occurrence of image smearing or image scraping.

  Further, the paper stacking apparatus according to the present invention (Claim 2) is that the paper return means is driven by the same drive source as that for conveying the paper in Claim 1, thereby reducing the size and cost of the apparatus. There is an effect that it is possible to achieve a reduction of the above.

  The paper stacking apparatus according to the present invention (Claim 3) is the paper stacking apparatus according to Claim 1 or 2, wherein the paper return means is provided with at least two positions of the paper return position and the paper holding position. It is not necessary to contact the sheet with the sheet, and the sheet holding position is arranged on the upstream side with respect to the sheet returning position, so that the sheet returning unit is brought into contact with the sheet end surface where there is no image. In addition, it is possible to reduce the degree of image contamination and image shaving.

  According to a fourth aspect of the present invention, there is provided a paper stacking device according to the third aspect, wherein when the paper is ejected to the paper ejection tray, the paper return means is set to the paper holding position, thereby When the paper is discharged, the trailing edge of the discharged paper is placed on the paper return means, and the deterioration of the stacking property caused by being pushed out to the downstream side where the paper return means does not reach can be avoided. Play.

  The paper stacking device according to the present invention (Claim 5) is the paper stacking apparatus according to Claim 3 or 4, wherein the paper return means is moved to a paper holding position where it is in contact with a paper having a low possibility that an image at the rear end of the paper exists as much as possible. By doing so, it is possible to suppress the occurrence of image contamination, image shaving, and the like while ensuring stackability.

  According to a sixth aspect of the present invention, there is provided a paper stacking apparatus according to the third, fourth, or fifth aspect, wherein the position of the paper return means is set to the paper holding position when the paper discharge tray is shifted. There is an effect that it is possible to suppress the occurrence of image smearing, image scraping, and the like by moving the sheet to a sheet holding position where the image is unlikely to exist.

  According to a seventh aspect of the present invention, there is provided the paper stacking apparatus according to any one of the third to sixth aspects, wherein the paper discharge state and the alignment state are determined according to the detection result of the paper detection means arranged in the paper transport path. By determining, it is possible to determine the movement timing of the sheet returning means without providing a special sheet state detecting means, and it is possible to achieve cost reduction.

  Exemplary embodiments of a paper stacking apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings.

(Embodiment)
The present invention relates to a discharge tray for stacking sheets to be stacked, tray shift means for shifting the discharge tray in a direction orthogonal to the discharge direction of the sheet, and discharging the sheet discharged onto the discharge tray. A sheet return means for returning to the upstream side in the direction and aligning the rear end of the sheet, a movement means for moving the sheet return means to a predetermined position, and a tray control means for controlling each part including the movement means. Is configured to move the contact position of the paper return means to the paper according to the discharge state of the paper by the moving means, avoid deterioration of stackability, and keep the paper return means in contact at the same place, By moving the contact position, it is possible to reduce the occurrence of image smearing or image shaving. This will be specifically described below.

  FIG. 1 is an external view showing an example in which a paper stacking apparatus according to an embodiment of the present invention is mounted on an image forming apparatus. As shown in the drawing, a paper stacking device 200 having a tray 4 is mounted on the paper discharge port side of an image forming apparatus 100 such as a copying machine. The configuration and operation of the paper stacking apparatus 200 will be described in detail below.

  FIG. 2 is an explanatory diagram showing a cross-sectional configuration of the paper stacking apparatus according to the embodiment of the present invention. In the figure, reference numeral 1 is a conveyance roller for receiving a sheet discharged from the image forming apparatus 100, reference numeral 2 is a discharge roller for discharging the received sheet to the tray 4, and reference numeral 3 is a sheet interlocking with the discharge roller 2. Returning member, reference numeral 5 is a drive motor for conveyance, reference numeral 6 is a tray shift motor which is a drive source for shifting the tray 4 in the horizontal direction, and reference numeral 7 is for driving the tray 4 up and down (vertical direction). A tray up / down motor, 9 is an end fence that abuts the rear end of the sheet and serves as an alignment reference surface of the rear end of the sheet.

  In FIG. 2, the sheet conveyed from the image forming apparatus 100 to the sheet stacking apparatus 200 is discharged onto the tray 4 by the transfer roller 1 and the discharge roller 2 that are rotated by the drive motor 5. A conveyance sensor 8 is provided between the conveyance roller 1 and the paper discharge roller 2 to detect the conveyance state of the paper, that is, the presence or absence of the paper. The paper discharged on the tray 4 is returned to the upstream side in the paper discharge direction by the paper return member 3 and aligned so that the rear ends of the paper are aligned. The paper return member 3 is configured to be interlocked with the shaft of the paper discharge roller 2. Further, the tray 4 is provided with a shift mechanism that moves the tray 4 in the front-rear direction orthogonal to the paper discharge direction, and a tray shift motor 6 that drives the shift mechanism. This realizes a configuration in which the sheets are shifted and sorted in the front-rear direction. Further, as will be described later, a tray position detection unit that determines a tray stop position when shifting the tray 4 is provided inside the shift mechanism. Further, a mechanism for moving the tray 4 in the vertical (vertical) direction according to the number of sheets stacked is provided.

  FIG. 3 is an explanatory diagram illustrating the configuration of the shift mechanism and the tray position detection unit of the paper stacking apparatus according to the embodiment of the present invention. As shown in the figure, the rotation of the tray shift motor 6 is transmitted to the worm gear 36 via the timing belt, and is transmitted to the worm wheel 35 that meshes with the worm gear 36. The worm wheel 35 has a pin 37 attached at an eccentric position, and the pin 37 is loosely fitted in a long hole 9 a that is long in the vertical direction of the end fence 9. Further, the tray 4 is suspended and attached to the end fence 9.

  Therefore, the rotation of the tray shift motor 6 becomes the rotation of the worm wheel 35, and the end fence 9 is shifted in the front-rear direction perpendicular to the paper discharge direction by rotating the pin 37. Since the tray 4 is attached to the end fence 9, the tray 4 shifts in synchronization with the end fence 9. Further, in this way, the shift mechanism is configured such that the tray 4 reciprocates once in the front-rear direction by one rotation of the worm wheel 35.

  The worm wheel 35 is integrally provided with a rotation detection plate 38 whose center of rotation is coaxial, and the rotation detection plate 38 is provided with a plurality of slits 38a corresponding to the tray stop position. Further, a slit position sensor 32 for detecting the position of the slit 38a is provided.

  FIG. 4 is an explanatory view showing the configuration of the sheet return member 3 portion. This figure shows a configuration example of one sheet return member 3 on the left and right (two in total), and the operation is the same. The pulleys 13, 14, 15, 16, and 17 are used to rotate the shaft 22 of the paper discharge roller 2, and the timing belts 10, 11, and 12 are wound around each of them to constitute a drive transmission system. Then, the sheet return member 3 assembled integrally with the timing pulley 17 is rotated. The pulley 13 is assembled integrally with the shaft 22. The pulleys 14 and 15 are assembled integrally with the shaft 23. The pulley 16 is a two-stage pulley and is attached to the shaft of the folder 18. The pulley 17 is attached to the shaft of the folder 24 (see FIG. 5A). The other end of the folder 24 is rotatably attached to a shaft to which the pulley 16 of the folder 24 is attached. However, the maximum movable angle is regulated by the shape of the folder. Further, a connection member 19 is attached to the folder 18, and the other end is attached to a solenoid 20 which is a sheet return member moving means.

  FIG. 5A is an explanatory diagram illustrating a state when the paper return member 3 is in the paper return position. The contact position point A between the sheet return member 3 and the tray 4 is about 10 mm away from the end fence 9. At this time, the solenoid 20 is pulled by a spring (not shown) in a non-suction (OFF) state, and the folder 18 comes into contact with the folder stopper 21 and stops.

  FIG. 5B is an explanatory diagram illustrating a state when the paper return member 3 is in the paper holding position. The solenoid 20 is in the suction (ON) state and pulls the folder 18 toward the solenoid 20 side. Further, since the folder 24 to which the paper return member 3 is attached is rotatably attached to the folder 18, the position of the paper return member 3 moves to the solenoid 20 side, and the paper return member 3 and the tray 4 are moved. The contact position is the position of the point B, and the position of the point B is set to be, for example, a position about 2 mm away from the end fence 9.

  Further, in this state, when the solenoid 20 is brought into a non-suction (OFF) state, the folder stopper 21 is pulled by a spring (not shown), so that the position of the sheet return member 3 is in the state shown in FIG.

  Next, FIGS. 6-1 to 6-5 show the state up to conveyance, discharge, and rear end alignment (stacking) of the paper P. FIG. FIG. 6A is an explanatory diagram illustrating a state when the paper P is received from the image forming apparatus 100 and the leading edge of the paper P is discharged. Here, the conveyance sensor 8 is in a detection state. The solenoid 20 is in the suction (ON) state, and the position of the sheet return member 3 is at the sheet holding position.

  FIG. 6B is an explanatory diagram illustrating a state immediately after the paper P is discharged onto the tray 4. Here, the conveyance sensor 8 is in a non-detection state. The solenoid 20 is in the suction (ON) state, and the position of the sheet return member 3 is at the sheet holding position.

  FIG. 6C is an explanatory diagram illustrating a state in which the paper P is discharged onto the tray 4 and the rear end of the paper P is dropped on the tray 4. The conveyance sensor 8 is in a non-detection state. The solenoid 20 is in the suction (ON) state, and the position of the sheet return member 3 is at the sheet holding position. The time until the trailing edge of the paper P falls on the tray 4 after the trailing edge of the paper P is detected by the transport sensor 8 (when the detection state changes from the detection state to the non-detection state). If the time has elapsed, it is determined that there is a trailing edge of the paper P on the tray 4, and the position of the paper return member 3 is moved to the paper return position. That is, in order to align the rear end of the paper P, the paper return member 3 is moved to the rear end position of the paper P.

  6-4, the paper P is discharged onto the tray 4, the rear end of the paper P falls on the tray 4, the solenoid 20 is in a non-suction (OFF) state, and the position of the paper return member 3 is changed to the paper return. It is explanatory drawing which shows the state moved to the position.

  6-5 is an explanatory diagram illustrating a state in which the paper P discharged onto the tray 4 is aligned by the paper return member. After the solenoid 20 is in the non-suction (OFF) state, a time until the trailing edge of the sheet is aligned by the sheet returning member 3 is set in advance, and when the time has elapsed, the trailing edge of the sheet P is aligned. Judging, the position of the paper return member 3 is moved to the paper holding position.

  FIG. 7 is a block diagram showing the configuration of the control system of the paper stacking apparatus according to the embodiment of the present invention. Each section of the paper stacking apparatus 200 is controlled by a main control plate. The main control board is controlled in a centralized manner by the CPU 25 connected in signal to the control unit 31 of the image forming apparatus 100. The CPU 25 includes a forward / reverse driver 27 for driving a drive motor 5 as a stepping motor, a forward / reverse driver 28 for driving a tray shift motor 6 as a DC motor, and a forward / reverse driver 29 for driving a tray up / down motor 7 as a DC motor. A ROM 26 storing a control program is connected. Further, the CPU 25 detects a paper P using a photo interrupter with a filler and feeds back a signal thereof, and a slit for detecting a shift driving slit position described later using a photo interrupter and feeding back the signal. A position detection sensor 32, a paper surface detection sensor 33 for detecting the paper surface position on the tray 4 using a photo interrupter with a filler and feeding back the signal, and a lower limit position of the tray 4 using a photo interrupter with a filler are detected and the signal is fed back. Each sensor of the tray lower limit detection sensor 34 to be connected is connected.

  That is, in FIG. 7, the entire sheet stacking apparatus 200 is controlled by the main control plate. The main control board includes a CPU 25 by a microcomputer system, and the CPU 25 is connected to the conveyance sensor 8, the slit position sensor 32, the drive motor 5, the tray shift motor 6, the tray up / down motor 7, and the like. Further, in order to communicate with the ROM 26 storing the control program and the control unit 31 of the image forming apparatus 100, they are electrically connected by an I / F cable. As a result, the power of the paper stacking apparatus 100 is also supplied from the image forming apparatus 100. The CPU 25 controls the tray position based on a control signal from the image forming apparatus 100, conveyance information of the paper P from the conveyance sensor 8, slit detection information on the rotation detection plate by the slit position sensor 32, and the like. Furthermore, since the conveyance information of the paper P is input from the conveyance sensor 8 by ON / OFF, it is also possible to detect the space between the paper P.

  Further, since the sheet conveyance information is obtained from the conveyance sensor 8 by ON / OFF, the trailing edge of the sheet can be detected, and the timing of the suction / non-suction (ON / OFF) of the solenoid 20 can be recognized. The movement control of the sheet return member 3 can be performed.

  Next, the operation up to the paper discharge process will be described with reference to the flowchart shown in FIG. The control in this figure is executed by the CPU 25. When the sheet passing is started, first, the drive motor 5 and the solenoid 20 are turned on to set the sheet return member 3 to the sheet holding position (step S11). Subsequently, it is determined whether or not the paper has been passed (step S12). If the paper has not been passed, the paper is accepted (step S13), and it is determined whether or not the trailing edge of the paper has been detected (step S13). 14). If the trailing edge of the sheet is detected, time measurement is started or the number of pulses is checked (step S15), and it is determined whether or not a predetermined time has passed (step S16). If it is determined that the predetermined time has elapsed, the solenoid 20 is turned off and the paper return member 3 is set to the paper return position (step S17). Subsequently, time measurement is started or the number of pulses is confirmed (step S18), and it is determined whether a predetermined time has elapsed (step S19). If it is determined that the predetermined time has elapsed, the solenoid 20 is turned on, and the paper return member 3 is set to the paper holding position (step S20). Subsequently, it is determined whether or not there is a tray shift request (step S21). If it is a tray shift request, the tray shift is executed (step S22). On the other hand, if the sheet passing is completed in step S12, the solenoid 20 is turned off before the drive motor 5 is turned off (step S23). The solenoid 20 is turned off before the drive motor 5 is turned off in order to prevent the paper return member 3 from moving and pushing out the paper by turning off the solenoid 20 in this way. After the solenoid 20 is turned off, time measurement is started (step S24), and it is determined whether or not a predetermined time has elapsed (step S25). Here, if a predetermined time has elapsed, the drive motor 5 is turned off (step S26).

  Therefore, according to the paper stacking apparatus 200 of the embodiment described above, the following effects can be obtained. First, by moving the contact position of the sheet return member 3 to the sheet by the solenoid 20 according to the discharge state of the sheet, deterioration of stackability is avoided and the sheet return member 3 is kept in contact at the same place. Instead of moving the contact position, it is possible to reduce the occurrence of image smearing or image shaving. Second, the paper return member 3 is driven by the same drive source (drive motor 5) as the means for transporting the paper, so that the apparatus can be downsized and the cost can be reduced.

  Third, by providing at least two positions of the sheet return member 3 of the sheet return position and the sheet holding position, the sheet return member 3 does not need to contact the sheet at the same position, and the sheet holding position Is placed upstream of the paper return position, so that the paper return means is brought into contact with the paper end face side where no image is present, thereby reducing the degree of image smear and image scraping. Further, since the time required for alignment of the trailing edge of the sheet is short, there is no problem of image smearing or image scraping. In addition, since the next paper waiting time is longer than the alignment time at the rear end of the paper, the paper return member 3 is moved to the rear end of the paper as much as possible. Thus, the occurrence of image contamination and image shaving is suppressed.

  Fourth, when the paper is discharged to the tray 4, the position of the paper return member 3 is set to the paper holding position so that when the rear edge of the paper is discharged, the rear edge of the discharged paper is returned to the paper. It is possible to avoid the deterioration of the stacking property that occurs on the member 3 and is pushed out to the downstream side where the paper return member 3 does not reach. Fifth, by moving the paper return member 3 to a paper holding position that comes into contact with a paper that is unlikely to have an image at the rear edge of the paper as much as possible, image stacking, image scraping, etc. can be achieved while ensuring stackability. Occurrence can be suppressed. Sixth, by shifting the position of the sheet return member to the sheet holding position when the tray 4 is shifted, the sheet is moved to a sheet holding position that is in contact with a sheet that is unlikely to have an image at the rear end of the sheet. Occurrence of image shaving or the like can be suppressed. Seventh, by determining the paper discharge state and alignment state according to the detection result of the transport sensor 8 arranged in the paper transport path, the movement timing of the paper return means can be determined without providing any special paper state detection means. It is possible to reduce the cost.

  In the above-described embodiment, the configuration and operation example in which the paper return member 3 is moved to the paper return position and the paper holding position by the solenoid 20 have been described. However, the present invention is not limited to this. For example, it is possible to realize a paper stacking apparatus that provides the same effect by providing a plurality of paper return members with different contact positions such as a paper return position and a paper holding position and performing the contact timing in the same manner as described above. it can.

  As described above, the paper stacking apparatus according to the present invention is connected to various image forming apparatuses such as copying machines, printers, and facsimile machines, and is useful for a paper stacking apparatus that shifts and sorts a sheet bundle for each job. In particular, it is suitable for an apparatus that satisfactorily aligns the trailing end of a sheet bundle from an image forming apparatus or the like.

1 is an external view showing an example in which a paper stacking apparatus according to an embodiment of the present invention is mounted on an image forming apparatus. It is explanatory drawing which shows the cross-sectional structure of the paper stacking apparatus concerning embodiment of this invention. It is explanatory drawing which shows the structure of the shift mechanism and tray position detection part of the paper stacking apparatus concerning embodiment of this invention. It is explanatory drawing which shows the structure of the paper return mechanism of the paper stacking apparatus concerning embodiment of this invention. It is explanatory drawing which shows the state of the paper return position of the paper return member concerning embodiment of this invention. It is explanatory drawing which shows the state of the paper holding position of the paper return member concerning embodiment of this invention. FIG. 10 is an explanatory diagram illustrating a state when a sheet P is received from the image forming apparatus and the leading end of the sheet is discharged. FIG. 6 is an explanatory diagram illustrating a state immediately after a sheet is discharged to a tray. FIG. 6 is an explanatory diagram illustrating a state where a sheet is discharged to a tray and a rear end of the sheet P is dropped on the tray. FIG. 6 is an explanatory diagram illustrating a state in which a sheet is discharged to a tray, a trailing end of the sheet is dropped on the tray, a solenoid is in a non-suction (OFF) state, and a position of a sheet returning member is moved to a sheet returning position. . FIG. 6 is an explanatory diagram illustrating a state in which sheets discharged onto a tray are aligned by a sheet return member. It is a block diagram which shows the structure of the control system of the paper stacking apparatus concerning embodiment of this invention. It is a flowchart which shows the operation | movement from paper reception to tray shift concerning embodiment of this invention.

Explanation of symbols

3 Paper return member 4 Tray 5 Drive motor 8 Conveyance sensor 25 CPU
26 ROM
100 image forming apparatus 200 paper stacking apparatus

Claims (7)

A paper discharge tray for loading the paper to be loaded;
Tray shift means for shifting the paper discharge tray in a direction perpendicular to the paper discharge direction;
A paper return means for returning the paper discharged onto the paper discharge tray to the upstream side in the discharge direction and aligning the trailing edge of the paper;
Moving means for moving the paper return means to a predetermined position;
Tray control means for controlling each part including the moving means;
With
The paper stacking device, wherein the tray control means moves the contact position of the paper return means to the paper by the moving means in accordance with the discharge state of the paper.   2. The sheet stacking apparatus according to claim 1, wherein the sheet returning unit is driven by the same drive source as the unit that conveys the sheet.   3. The position of the sheet return means is provided at least at two positions, a sheet return position and a sheet holding position, and the sheet holding position is disposed upstream of the sheet return position. Paper loading device.   4. The paper stacking apparatus according to claim 3, wherein a position of the paper return means when the paper is discharged to the paper discharge tray is the paper holding position.   5. The paper stacking apparatus according to claim 3, wherein the paper returning unit is moved to a position in contact with the paper on the rear end side of the paper after aligning the paper discharged to the paper discharge tray. .   6. The paper stacking apparatus according to claim 3, wherein the tray control means sets the paper return means to the paper holding position when the paper discharge tray is shifted. Furthermore, a paper detection means for detecting the conveyance state of the paper is provided,
The said tray control means judges the discharge | emission state and alignment state of a sheet | seat according to the detection result of the said sheet | seat detection means, and moves the said sheet | seat return means. Paper loading device.

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