JP2007008632A - Paper sheet stacking device, and post-processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper sheet stacking device which is capable of smoothly introducing paper sheets on an inclined stacking table, and smoothly discharging a bundle of the stacked paper sheets, and consistently operated while the probability of occurrence of defective conveyance is sufficiently low, and a post-processing device having the paper sheet stacking device. <P>SOLUTION: When paper sheets are stacked on a paper sheet stacking table, a paper sheet holding member is moved to a separating position. When the paper sheets are pushed up and discharged, the paper sheet holding member is moved to the holding position, and pushed up by a discharging means, and paper sheets are discharged. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sheet stacking apparatus that stacks sheet-shaped sheets and a post-processing apparatus having the sheet stacking apparatus.

  A high-speed image forming apparatus such as an electrophotographic image forming apparatus is often used in combination with a post-processing apparatus that performs post-processing such as stapling, punching, folding, and shifting on a sheet on which an image is formed. However, a sheet processing apparatus represented by a post-processing apparatus is generally equipped with a sheet stacking apparatus that stacks a plurality of sheets to form a bundle of sheets.

  Many paper stacking devices require a function of stacking the edges of sheets fed one by one or several at a time in the vertical and horizontal directions, and easily align the edges in the vertical direction, that is, the transport direction of the fed paper. For this purpose, or in order to reduce the size of the apparatus, there are many integrated apparatuses in which an integrated table is formed on an inclined surface.

  In the stacking apparatus having the stacking table as an inclined surface, the sheet alignment is improved, but the performance of stacking the sheets densely decreases. This is a problem that, as a result of the inclination of the sheets to be stacked, the gravity acting on the sheets decreases, causing the swelling of the stacked sheets or the sheets to buckle.

In Patent Document 1, a brush roller is used in the vicinity of the stacking table in order to prevent paper swell and buckling, and the configuration of the brush roller is devised.
JP-A-10-297815

  According to the method of Patent Document 1, it is not possible to sufficiently prevent the paper from being swelled or buckled. The bulging of the paper on the stacking table is derived in various forms, and in the case of the tilted stacking table, the bulging and buckling may occur not only at the bottom, that is, at the end of the sheet, but also at the center of the sheet. When a brush roller is used, it is effective for preventing swelling and buckling in the lower part, but it is not sufficient for preventing swelling and buckling in the upper part. If a brush roller is provided above in order to prevent bulging and buckling in the upper direction, when the paper is introduced into the stacking device, the brush roller becomes an obstacle, and the paper may not be stacked smoothly.

  Also, in order to discharge a bundle of stacked sheets, the leading edge of the sheet is used as the trailing edge during discharging, and the trailing edge is pushed up to raise and discharge the bundle of sheets. , Pushing up is not performed smoothly, and there are cases where jams and other conveyance failures occur. Even if the paper does not swell, if the paper is not tight, the push-up and discharge are not performed smoothly, and jamming may occur.

  The present invention relates to a paper stacking apparatus that smoothly introduces a sheet to an inclined stacking base, smoothly discharges a stack of stacked sheets, has a sufficiently low probability of occurrence of conveyance failure, and operates stably. An object of the present invention is to provide a post-processing apparatus having a paper stacking apparatus.

The object is achieved by the following invention.
(Claim 1)
A paper stacking apparatus having an inclined stacking base, a stacking unit paper feeding means for feeding paper to the stacking base, a discharge means for pushing up and discharging a bundle of paper, and a pressing member for pressing the paper on the stacking base,
Control means for moving the pressing member to a pressing position that is in contact with or close to the stacking table and a spaced position that is separated from the stacking table and forms a transport path to the stacking table, When paper is fed to the stacking table, the pressing member is positioned at the separation position to form a paper feed conveyance path, and when discharging the bundle of stacked paper by the discharge means, A paper stacking apparatus, wherein the pressing member is positioned at the pressing position.
(Claim 2)
The pressing member includes a pressing roller, and the control unit rotationally drives the pressing roller so that the pressing roller has a conveying force in a discharging direction with respect to a sheet at the time of discharging. The paper stacking apparatus according to claim 1.
(Claim 3)
3. The control unit according to claim 1, wherein the control unit positions the pressing member at the separation position based on a paper feed signal indicating that paper is fed to the paper stacking device. Paper stacking device.
(Claim 4)
4. The control unit according to claim 1, wherein the control unit moves the pressing member from the separated position to the pressing position at a paper feeding time when the paper drops on the stacking table. 5. Paper stacking device.
(Claim 5)
5. The sheet stacking according to claim 4, wherein the control unit rotationally drives the pressing roller so that the pressing roller has a conveyance force for introducing the sheet into the sheet at the sheet feeding time. apparatus.
(Claim 6)
The paper stacking apparatus according to claim 1, wherein the stacking base has a paper stacking surface inclined at 60 ° or more with respect to the horizontal.
(Claim 7)
7. A post-processing apparatus comprising: the paper stacking apparatus according to claim 1; and a binding unit configured to bind a bundle of sheets stacked on the stacking table.
(Claim 8)
5. The paper stacking device and the paper according to claim 1, wherein the pressing member is positioned at the separation position based on a paper feed signal indicating that the paper is fed to the paper stacking device. A post-processing apparatus having a paper sensor provided at an inlet portion for receiving, wherein the paper feed signal is a paper detection signal of the paper sensor.

  According to the invention of any one of claims 1 to 8, the discharge of the sheet from the inclined stacking table is surely performed, and the discharge failure that is likely to occur when the sheet is inflated or the sheet is weak is surely prevented. .

  According to the second aspect of the invention, the paper is discharged more smoothly and reliably by assisting the pushing up and discharging of the paper by the pressing roller for pressing the paper.

  According to the fourth aspect of the present invention, a stable paper stacking apparatus is realized in which the paper feeding to the stacking table is reliably performed, and the paper feeding to the paper stacking apparatus and the paper stacking apparatus are reliably discharged. .

The present invention will be described below with reference to the illustrated embodiments, but the present invention is not limited to the embodiments.
<Image forming apparatus>
FIG. 1 is an overall configuration diagram of an image forming apparatus having a paper stacking apparatus and a post-processing apparatus according to an embodiment of the present invention.

  The image forming apparatus main body A is an image forming device in which a charging unit 2, an image exposing unit 3, a developing unit 4, a transfer unit 5A, a charge removing unit 5B, a separation claw 5C, and a cleaning unit 6 are arranged around a rotating photoreceptor 1. A portion GK, and the surface of the photosensitive member 1 is uniformly charged by the charging unit 2 and then externally via image data or a network obtained by reading from the document Ge to be copied by the laser beam of the image exposure unit 3 A latent image is formed by exposure based on the image data received from the image, and the latent image is reversely developed by the developing means 4 to form a toner image on the surface of the photoreceptor 1.

  On the other hand, the recording paper RS fed from the paper feed tray 7A, which is a paper feed storage means, is sent to the transfer position, and the toner image is transferred onto the recording paper RS by the transfer means 5A at the transfer position. Thereafter, the charge on the back surface of the recording paper RS is erased by the discharging means 5B, separated from the photoreceptor 1 by the separation claw 5C, transported by the intermediate transport section 7B, subsequently heated and fixed by the fixing means 8, and by the paper discharge roller 7C. Discharged.

  When image formation is performed on one side of the recording paper RS, the conveyance path switching plate 7D, which is one of the paper conveyance means, is switched to the position indicated by the dotted line.

  Further, the developer, that is, the toner remaining on the surface of the photoreceptor 1 after the image formation is removed by the cleaning unit 6 downstream of the separation claw 5C to prepare for the next image formation.

  On the other hand, when image formation is performed on both sides of the recording paper RS, the recording paper RS heated and fixed by the fixing unit 8 is conveyed downward by switching the conveyance path switching plate 7D to the position indicated by the solid line. After switching back and upside down in the reverse conveying means 7E which is one of the paper conveying means, a new toner image is transferred to the back surface at the transfer position.

  As will be described later, when the punching process, the folding process, the binding process, and the like are performed, the recording paper RS heated and fixed by the fixing unit 8 is moved downward by switching the conveyance path switching plate 7D to the position indicated by the solid line. After being conveyed and switched back and reversed by the reverse conveying means 7E, the sheet is raised with the rear end of the sheet at the top and discharged by the discharge roller 7C.

  The recording paper RS discharged from the paper discharge roller 7C is sent to the first post-processing device FS1.

  An operation display unit 9 that can select and set various image forming modes, paper post-processing modes, and the like is disposed on the upper front side of the image forming apparatus main body A. An image reading device B that is an image reading unit provided with an automatic document feeder G of a document moving type reading system is installed. Image data obtained by reading by the image reading device B and image data received from the outside by facsimile communication or network communication are stored in a storage device (not shown).

  The first post-processing device FS1 is a post-processing device that performs punching processing and folding processing, and the second post-processing device FS2 is a post-processing device that performs shift processing, binding processing, and middle folding processing.

  The first post-processing device FS1 includes a punching processing unit 12 and a folding processing unit 14, and the recording paper RS discharged from the image forming apparatus main body A and the cover sheet HS supplied from the cover sheet feeding tray 11 at the entrance 10 are provided. To perform punching or folding.

  As shown in the figure, the folding processing unit 14 has several branch conveyance paths, and performs various folding processes such as bi-folding and tri-folding by properly using the branch conveyance paths.

  A fixed paper discharge tray 30 used as a sub-tray is disposed in the upper stage of the second post-processing device FS2, the shift means 50 and the paper discharge means 60 are disposed along the substantially horizontal conveyance path h2, and the binding means 70 is disposed in the lower stage. And the center folding means 80 is arrange | positioned.

  In addition, a main tray 90 is disposed on the left side of the second processing unit FS2 for stacking sheets that have undergone shift processing and sheets that have undergone end-stitching (stapling) processing. A lower tray 91 for discharging paper is disposed.

  Next, the structure of 2nd processing apparatus FS2 is demonstrated based on FIGS. FIG. 2 is a diagram showing a main part of the paper stacking apparatus according to the embodiment of the present invention, and FIG. 3 is a plan view of the stacking table. In the following description, the recording paper RS and the cover HS are collectively referred to as the paper S.

  The sheet S discharged from the first post-processing device FS1 is introduced into the inlet 20 of the second post-processing device FS1.

  A paper branching unit including switching gates G1 and G2 is provided on the downstream side of the inlet 20. The switching gates G1 and G2 are driven by a solenoid (not shown) to select one of three transport paths, that is, the first transport path h1, the upper second transport path h2, and the lower third transport path h3. select.

  In forming a small number of images, the switching gate G1 blocks the second transport path h2 and the third transport path h3 and opens only the first transport path h1. The sheet S travels along the first transport path h <b> 1, is nipped by the transport roller 31 on the downstream side, rises, is discharged by the discharge roller 32, and is sequentially stacked on the sub-tray 30.

  Note that a maximum of 200 sheets S can be stacked on the sub-tray 30.

  In the large-volume image forming mode in which the stapling process is not performed, the switching gate G1 blocks the first transport path h1, the switching gate G2 blocks the third transport path h3, and opens the second transport path h2 to open the sheet S. Allow the passage of. Then, the paper S is guided and discharged to the main tray 90. In the mode in which the paper S is discharged to the main tray 90 through the second transport path h2, a shift process for shifting the paper S by the shift means 50 can be performed. The shift means 50 performs a shift process for changing the paper discharge position of the paper S in the width direction every predetermined number of sheets. The main tray 90 is configured to descend sequentially when a large number of sheets S are stacked. In the case of A4 or B5, the main tray 90 can accommodate a maximum of 3000 sheets.

  In the vicinity of the paper discharge roller 61 constituting the paper discharge means 60, a paper sensor PS2 for detecting the passage of the paper S discharged to the main tray 90 is disposed.

The bundle of sheets S collected on the intermediate stacker 71 is also conveyed obliquely downward, folded in the middle by the folding unit 80, and discharged to the lower tray 91.
<Paper accumulation>
Sheet accumulation will be described with reference to FIGS. FIG. 4 is a block diagram of a control system for controlling the stacking of sheets, and FIG. 5 is a diagram showing the operation timing of each part of the sheet stacking apparatus. As will be apparent from the following description, since the paper S is switched back and conveyed on the intermediate stacker 71, the leading edge and the trailing edge of the paper S are interchanged by reversing the conveying direction. The leading edge and trailing edge are defined with reference to the direction in which the tray 90 is discharged. That is, in FIG. 1, the left end of the sheet S is the leading end, and the right end is the trailing end. In FIG. 2, the upper left corner of the sheet S on the intermediate stacker 71 is the leading edge, and the lower right corner is the trailing edge.

  In the staple processing mode, the image-formed paper S sent to the inlet 20 of the second post-processing device FS2 is guided by the switching gate G2, sent to the lower third transport path h3, and narrowed by the transport roller 22. It is held and conveyed downward, and is then nipped by the conveyance roller 23 and conveyed. Further, it is conveyed obliquely upward along the intermediate stacker 71 inclined and conveyed by the downstream stacker discharge roller 24. The stacker discharge roller 24 is a stacking unit paper feeding unit that supplies the sheets S to the stacking table, and the stacking table for stacking the fed sheets includes an intermediate stacker 71 and a stopper 76. The intermediate stacker 71 is for stacking sheets S to be stapled, and has a large inclination angle with respect to the horizontal, in order to improve the alignment of the conveyance direction of the sheets S and to reduce the size of the post-processing apparatus. The inclination angle θ ≧ 60 ° with respect to the horizontal line HL is set.

  After the trailing edge of the conveyed paper S in the traveling direction passes through the stacker discharge roller 24, the paper S falls by its own weight, switches back, slides and falls on the inclined surface of the intermediate stacker 71, and near the binding means 70. The stopper 76 comes into contact with the sheet abutting surface and stops.

  Reference numeral 73 denotes a pair of width alignment members that are movably provided on both side surfaces of the intermediate stacker 71. The width aligning member 73 is composed of a pair of aligning plates movable in the width direction X perpendicular to the sheet conveying direction, and is fixed to the belt 74 driven by the motor M2, and when receiving the sheet S on the intermediate stacker 71, The pair of alignment plates form an interval wider than the sheet width, and when the pair of alignment plates abut against the stopper 72 and stop, the motor M2 drives to reciprocate in the width direction of the sheet S, that is, the X direction in FIG. Align the paper bundle in the width direction.

  When the set number of sheets is stacked and aligned on the intermediate stacker 71, the binding unit 70 performs binding, that is, stapling, and forms a bundle of sheets S.

  A discharge claw 72 serving as a discharge unit is fixed to the belt 74. After the stapling process, the belt 74 driven by the motor M1 moves up in the Y direction in FIG. It is discharged to the tray 90. The discharge claw 72 is at the home position shown in the figure, and when the paper is discharged, it rises together with the belt 74 to push up and discharge the paper S and return to the home position shown in the drawing.

  A pressing roller 75 as a pressing member presses the sheet S on the intermediate stacker 71 at a substantially central portion of the intermediate stacker 71. The pressing roller 75 is attached so as to be pivotable about a shaft 75a, and is rotated by a motor M3 (see FIG. 4) in a direction in which the sheet S is conveyed downward toward the stopper 76 or upward toward the paper discharge unit. Although driven, it is made of a sponge roller, and touches the paper S lightly and acts on the paper S with a light conveying force. That is, when the pressing roller 75 rotates so as to convey the sheet S downward, the sheet S whose rear end is locked by the stopper 76 is buckled by the conveying force of the pressing roller 75 or the pressing roller 75 is moved to the sheet S. When the sheet is rotated so as to be conveyed upward, the pressing roller 75 presses the sheet S with a contact pressure such that the sheet S does not move upward by the conveying force of the pressing roller 75. For this reason, when the pressing roller 75 is in the position indicated by the dotted line, it is in contact with or not in contact with the intermediate stacker 71.

  The pressing roller 75 is turned by the solenoid SD between the solid line position and the dotted line position in the figure.

  Next, the operation in the staple process will be described with reference to FIG.

  In the initial state, the holding roller 75 is at a position (separated position) indicated by a solid line in the figure, and a space is formed between the stacker discharge roller 25 and the intermediate stacker 71 so that the sheet S can be introduced into the intermediate stacker 71. Form a road. The sheet S is transported along the third transport path h <b> 3 and proceeds upward along the intermediate stacker 71 by the stacker discharge roller 24. When the trailing edge of the sheet S moves away from the stacker discharge roller 24, the sheet S falls due to gravity, but a sheet sensor PS3 is disposed at the position of the stacker discharge roller 24 to detect the passage of the trailing edge of the sheet S.

  The solenoid SD is actuated by the paper rear end detection signal of the paper sensor PS3 and the pressing roller 75 is moved to the dotted line position (pressing position) to press the paper S against the intermediate stacker 71 and at the same time the motor M3 is rotated forward. The pressing roller 75 rotates counterclockwise (forward rotation), and assists in dropping the paper S downward. With such movement and forward rotation of the pressing roller 75, the sheet S surely reaches the stopper 76 and stops, the trailing ends of the sheet S are aligned, and the sheet S is in close contact with the intermediate stacker 71. Stop. Next, while the forward rotation of the pressing roller 75 is stopped, the motor M2 is operated and the alignment member 73 is reciprocated to align the paper S in the width direction. Stopping of the pressing roller 75 and starting of the operation of the alignment member 73 are performed when a predetermined time has elapsed since detection of the rear end of the sheet sensor PS3.

  The next sheet S is discharged from the first post-processing device FS1, and the solenoid SD is stopped based on a detection signal as a sheet feeding signal when the sheet sensor PS1 disposed at the entrance 20 detects the passage of the leading edge of the sheet S. The pressing roller 75 moves to the separated position of the solid line. Based on the signal that the sheet S further advances and the sheet sensor PS3 detects the trailing edge, the solenoid SD is activated to move the pressing roller 75 from the separated position of the solid line to the pressed position of the dotted line, and the motor M3 is rotated forward. Then, the forward rotation in the direction in which the sheet S is conveyed downward is started. In other words, the pressing roller 75 is positioned at the pressing position during the paper feeding time that is a period in which the sheet S is supplied from the stacker discharge roller 24 to the intermediate stacker 71 and reaches the stopper 76. Further, the operation described for the preceding sheet S is performed, and the succeeding sheet S is stacked on the preceding sheet S of the intermediate stacker 71 in an aligned state.

  In this way, the pressing member 75 is positioned at the separation position by the paper feed signal, and moves to the pressing position immediately before reaching the intermediate stacker 71 to press the paper. The paper feed signal is a signal indicating that the paper is supplied to the second post-processing device FS2. As shown in the drawing, the paper-feeding signal is provided at the entrance 20 of the second post-processing device FS2 and includes a signal from the paper sensor PS1. Alternatively, it may be a signal from a paper sensor provided at the inlet 10 of the first post-processing device or a signal from a paper sensor provided at the paper discharge unit of the image forming apparatus main body A. The paper feeding time when the pressing member is set to the pressing position is a time including at least the time when the paper S falls off the intermediate stacker 71.

  The operation described above is performed on the set number of sheets S, and the set number of sheets S are stacked on the intermediate stacker 71 in an aligned state.

  Next, the binding unit 70 operates to perform a stapling process on the bundle of sheets S.

  When the stapling process is completed, the motor M1 rotates to raise the discharge claw 72 and push up the bundle of sheets S. Simultaneously with the operation of the discharge claw 72, the motor M3 rotates in the reverse direction, and the pressing roller 75 rotates in the clockwise direction (reverse rotation) to assist in pushing up the paper S. The bundle of sheets S pushed up by the discharge claw 72 is discharged to the main tray 90 by the paper discharge roller 60.

  After discharging to the main tray 90, the motor M1 further rotates to return the discharge claw 72 to the home position, the motor M3 stops, the rotation of the pressing roller 75 stops, and the solenoid SD stops to press. The roller 75 rises to the separated position.

  As described above, when the sheet S is continuously supplied to the second post-processing device FS2, the pressing roller 75 is in the pressing position indicated by the dotted line in the interval between the preceding sheet S and the succeeding sheet S. The paper S is held down. When the inclination angle θ of the intermediate stacker 71 is large, the paper S tends to buckle on the intermediate stacker 71. When the intermediate stacker 71 buckles, the entry space of the paper S into the intermediate stacker 71 is narrowed by the preceding paper S, and jammed. However, as described above, buckling can be prevented by pressing the sheet S in the interval between the sheets by the pressing roller 75 as described above. It is preferable to stop the rotation of the pressing roller 75 while the sheet S is being pressed.

  In the continuous image formation in which a plurality of sheets S are bundled, in the double-sided image formation mode and the folding processing mode in the first post-processing device FS1, the paper feed interval, that is, the interval between the sheets fed back and forth becomes wide. The time during which the sheet S is stacked on the intermediate stacker 71 becomes longer, and swelling and buckling are likely to occur. However, since the pressing roller 75 presses the sheet at the sheet feeding interval, such a phenomenon is sure. To be prevented.

  Further, as shown in FIG. 5, the pressing roller 75 is in the pressing position while the discharge claw 72 pushes up the bundle of sheets S, and rotates in the reverse direction to assist in pushing up and discharging the bundle of sheets S. Thereby, the bundle of sheets S is reliably discharged.

  If the sheet S is thin or folded, the bundle of sheets S may not be discharged and jammed only by pushing up the rear end by the discharge claw 72. By pushing up the sheet S while suppressing the bundle of sheets S, the pushing up and discharging are ensured. At this time, the discharge is further ensured by driving the pressing roller 75 in the reverse rotation direction, that is, in the discharge direction.

1 is an overall configuration diagram of an image forming apparatus having a paper stacking apparatus and a post-processing apparatus according to an embodiment of the present invention. It is a figure which shows the principal part of the paper stacking apparatus which concerns on embodiment of this invention. It is a top view of an integration stand. FIG. 3 is a block diagram of a control system that performs sheet accumulation control. FIG. 4 is a diagram illustrating the operation timing of each unit of the paper stacking apparatus.

Explanation of symbols

A Image forming device (main unit)
FS1 First post-processing device FS2 Second post-processing device 15 Stacker discharge roller 70 Binding means 71 Intermediate stacker 72 Stopper 73 Alignment member 75 Pressing roller CR control means PS1 to PS3 Paper sensor

Claims (8)

A paper stacking apparatus having an inclined stacking base, a stacking unit paper feeding means for feeding paper to the stacking base, a discharge means for pushing up and discharging a bundle of paper, and a pressing member for pressing the paper on the stacking base,
Control means for moving the pressing member to a pressing position that is in contact with or close to the stacking table and a spaced position that is separated from the stacking table and forms a transport path to the stacking table, When paper is fed to the stacking table, the pressing member is positioned at the separation position to form a paper feed conveyance path, and when discharging the bundle of stacked paper by the discharge means, A paper stacking apparatus, wherein the pressing member is positioned at the pressing position. The pressing member includes a pressing roller, and the control unit rotationally drives the pressing roller so that the pressing roller has a conveying force in a discharging direction with respect to a sheet at the time of discharging. The paper stacking apparatus according to claim 1. 3. The control unit according to claim 1, wherein the control unit positions the pressing member at the separation position based on a paper feed signal indicating that paper is fed to the paper stacking device. Paper stacking device. 4. The control unit according to claim 1, wherein the control unit moves the pressing member from the separated position to the pressing position at a paper feeding time when the paper drops on the stacking table. 5. Paper stacking device. 5. The sheet stacking according to claim 4, wherein the control unit rotationally drives the pressing roller so that the pressing roller has a conveyance force for introducing the sheet into the sheet at the sheet feeding time. apparatus. The paper stacking apparatus according to claim 1, wherein the stacking base has a paper stacking surface inclined at 60 ° or more with respect to the horizontal. 7. A post-processing apparatus comprising: the paper stacking apparatus according to claim 1; and a binding unit configured to bind a bundle of sheets stacked on the stacking table. 5. The paper stacking device and the paper according to claim 1, wherein the pressing member is positioned at the separation position based on a paper feed signal indicating that the paper is fed to the paper stacking device. A post-processing apparatus having a paper sensor provided at an inlet portion for receiving, wherein the paper feed signal is a paper detection signal of the paper sensor.

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