JP2008120547A - Sheet stacker and image forming system provided therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To certainly sequentially stack sheets to be conveyed at a high speed while holding the sheets stacked on a tray in a correct position. <P>SOLUTION: This sheet stacker is provided with a paper discharging port for delivering sheet, a tray for storing the sheet, a paper pressing means pressing at least one side edge of the sheet on the tray, and a shifting means moving the paper pressing means between an operation position engaged with the uppermost sheet on the tray and a retraction position retracted. The paper pressing means has a sheet pressing piece for pressing the sheet on the tray. When the sheet pressing piece is moved from the operation position to the retraction position, the sheet pressing piece is moved on a moving track having a rotating track moved in a paper surface direction between a sheet edge and its outer side with respect to the uppermost sheet on a tray means and a vertically moving track vertically moving with respect to the sheet surface, and falls onto the paper surface after rotated from the outer side to the paper surface direction or falls onto the paper surface while rotating from the outer side to the paper surface direction, or rotates in the paper surface direction after falling onto the paper surface side, with respect to the uppermost sheet on the tray. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet stacking apparatus that stacks and stores sheets sequentially conveyed from an image forming apparatus such as a copying machine and a printer on a tray unit, and relates to an improvement of a sheet stacking mechanism that stores sheets discharged in an orderly manner on a tray.

  In general, this type of sheet stacking apparatus is widely used for stacking and storing sheets carried out from an image forming apparatus such as a printing machine or a copying machine on a tray unit disposed below a sheet discharge port. This type of device forms a step at the discharge outlet of the image forming apparatus and provides a tray. The sheet is then carried out with the discharge rollers and belt provided at the discharge outlet, and the sheets are stacked and stored on the tray. is doing. Therefore, when storing sheets from the paper discharge port, there is a possibility that the sheets that are already stacked are misaligned. When a large capacity sheet is stacked on the tray, the stacking posture of the sheets gradually increases. May cause the cargo to collapse. Therefore, a paper pressing mechanism that presses and holds the uppermost sheet accumulated on the tray is required.

Conventionally, such a paper pressing mechanism is provided with, for example, a paper pressing piece that hangs down on the tray from above the paper discharge port in Patent Document 1, and when the sheet is carried out, the leading edge of the sheet faces the paper pressing piece upward. A mechanism has been proposed in which a paper pressing piece presses the uppermost sheet after the sheet is pushed up and carried out, and the sheet is carried out. If a mechanism for providing the paper pressing piece for pressing and holding the sheet on the tray at a position past the sheet carry-out path is employed, the leading edge of the sheet from the paper discharge port may be obstructed by the paper pressing piece, thereby causing a sheet jam. There is. At the same time, when the leading edge of the sheet to be conveyed moves along the uppermost sheet that has already been accumulated, there is a problem that the sheet is displaced.
Therefore, it is conceivable to provide a paper pressing piece that swings up and down between the paper discharge outlet and the tray means. In this case, the paper discharge outlet is configured to swing the paper pressing piece in the sheet stacking direction (vertical direction). A mechanism to be arranged on the side is conceivable.
JP 2005-263355 A

  As described above, when pressing and holding the uppermost sheet stacked on the tray, it is necessary to retract the pressing piece to the outside of the tray every time the sheet is carried out. Since the sheet pressing piece is suspended from the sheet discharge path, the sheet from the sheet discharge port may be jammed by the sheet pressing piece. For example, as shown in FIG. 14, a paper pressing piece 103 is suspended above the tray 101 from above the tray 101, and the paper pressing piece 103 is pushed up by a sheet from the paper discharge port 102 and discharged onto the tray. When the sheet on the tray is pressed by its own weight, the sheet may be jammed (jammed) depending on the state of the sheet pressing piece 103 when the sheet front end is carried out from the sheet discharge port 102. When the trailing edge of the conveyed sheet is curled, it may be pushed up and stored on the paper pressing piece. In any of such cases, the subsequent sheet cannot be carried out normally.

  There is a problem that the uppermost sheet is displaced due to the sheet carried out in the same manner as described above. In addition, when this paper holding piece is arranged above the tray below the paper discharge port, when the sheet is carried out from the paper discharge port, the uppermost sheet on the tray is pressed and held, and the sheet falls onto the tray. The paper pressing piece can be retracted out of the tray immediately before the operation. However, such a paper pressing mechanism has the following problems. If, for example, a paper pressing piece that swings in the vertical direction is provided between the paper discharge port and the tray, this paper pressing piece interferes with the trailing edge of the sheet falling from the paper discharge port when retracted to the outside of the tray. There is a risk of disturbing the seat posture.

  That is, the paper pressing piece is required to press and hold the uppermost sheet as much as possible in the process of carrying out the sheet from the paper discharge port, and to quickly retreat immediately before the sheet falls from the paper discharge port. At this time, if the paper pressing piece moves upward from the uppermost sheet and retreats out of the tray, there is a problem that the posture of the next sheet falling during the retreating operation is disturbed or a jam occurs. At the same time, the step between the paper discharge port and the tray means must be set large because the paper pressing piece moves up and down between the paper discharge port and the paper discharge port. Therefore, there are problems that the posture of the falling sheet is disturbed and the apparatus is enlarged.

SUMMARY OF THE INVENTION Accordingly, the main object of the present invention is to provide a sheet stacking apparatus capable of sequentially and reliably stacking sheets conveyed at high speed while holding the sheets stacked on the tray in a correct posture.
Further, according to the present invention, a paper pressing mechanism that presses and holds sheets stacked on the tray and retracts to the outside of the tray when the next sheet is stacked is incorporated in a limited space between the discharge port and the tray means with a simple structure. It is an object of the present invention to provide a sheet stacking apparatus capable of performing the above.

  To achieve the above object, the present invention employs the following configuration. A paper discharge port for sequentially carrying out the sheets, a tray means for stacking and storing the sheets from the paper discharge opening disposed below the paper discharge opening, and paper for pressing the sheets stacked on the tray means A pressing unit; and a shift unit that moves between an operating position where the sheet pressing unit engages with the uppermost sheet on the tray unit and a retracted position retracted from the uppermost sheet. The paper pressing means has a sheet pressing piece that presses the uppermost sheet on the tray means, and when the sheet pressing piece moves between the operating position and the retracted position, It moves so that it may move on the movement locus | trajectory which has the rotation locus | trajectory which moves along a vertical movement locus | trajectory which moves along an up-down direction with respect to a sheet | seat surface.

  When the sheet pressing piece moves from the retracted position to the operating position, the sheet pressing piece is rotated (1) in the paper surface direction and then lowered onto the paper surface with respect to the uppermost sheet on the tray means, or (2) rotated in the paper surface direction. (3) It is configured to rotate in the paper surface direction after descending to the paper surface side.

  The shift means moves the paper pressing means from the operating position to the retracted position before the sheet carried out from the paper discharge port falls on the tray means, and then the sheet is accumulated on the tray means and then the retracted position. To move to the operating position.

  The tray means is arranged so as to stack sheets in a substantially horizontal posture, and the sheet pressing piece rotates in the horizontal direction from the retracted position and then descends in the vertical direction and moves to the operating position. Constitute. In this case, the base end portion of the sheet pressing piece is rotatably supported by a substantially cylindrical shaft member. The shaft member and the base end portion of the sheet pressing piece have a cam groove on one side and a cam follower on the other side. Form to fit. The cam groove is formed so as to rotate within a predetermined angle range when the sheet pressing piece moves up and down, and the shift means drives and transmits the sheet pressing piece so as to move up and down.

  The paper pressing means includes first and second sheet pressing pieces for pressing both side edges of the uppermost sheet on the tray means, and the tray means presses the edge of the uppermost sheet in the paper discharge direction. An end locking member is provided.

  The tray means includes a jog means for setting a reference position for aligning front and rear ends of the sheet from the paper discharge port in the paper discharge direction, and offsetting the sheet from the paper discharge port by a predetermined amount in the front and rear direction. The sheet pressing piece of the paper pressing unit is arranged so as to press the sheet at a position away from the reference position by an offset amount.

  The jog means may be (1) a restriction position moving means for moving the front end restricting means for abutting and restricting the front end of the sheet from the paper discharge port to move back and forth in the paper discharge direction, The tray position moving means moves to

  In addition, an image forming system according to the present invention includes an image forming apparatus having an image forming unit for forming an image on a sheet, and a sheet that is sequentially disposed on the tray unit and disposed at a paper discharge port of the image forming apparatus. A sheet stacking device is provided, and the sheet stacking device has the above-described configuration.

The present invention provides a movement locus having a turning locus for turning a paper pressing piece that presses and supports the uppermost sheet stacked on the tray means in the paper surface direction on the tray and a vertical movement locus that moves up and down on the sheet surface. Thus, the movement between the pressing position and the retracted position provides the following effects. The paper pressing piece moves in the paper direction between the edge of the uppermost sheet and the outside of the uppermost sheet and moves quickly between the operating position and the retracted position. By moving in time, the uppermost sheet can be pressed and held immediately before the sheet drops onto the tray from the sheet discharge outlet.
Therefore, the sheets stacked on the tray are not displaced by the next sheet carried out from the sheet discharge port. Further, since the paper pressing piece moves between the operating position above the tray and the retracted position outside the tray, the paper pressing piece moves along a trajectory and a vertical movement trajectory. It does not interfere with the sheet falling from the paper mouth, disturb its posture, or cause a jam.

  Further, since the paper pressing piece of the present invention moves to the retracted position along the trajectory of the upper tray and the vertical movement trajectory, the level difference between the paper discharge port and the tray means is set to be relatively small. It is possible to set the optimum value for carrying out the sheet from the paper mouth, and it is possible to configure the apparatus in a small space-saving manner.

  Further, according to the present invention, the sheet pressing piece is configured to move up and down from an operating position in contact with the sheet between the operating position and the retracted position with respect to the uppermost sheet on the tray, and then rotate in the paper surface direction. There is an effect that the posture of the seat is not disturbed when contacting or separating from the sheet.

  Hereinafter, the present invention will be described in detail on the basis of an embodiment in which the present invention is employed. FIG. 1 shows an image forming system provided with a sheet stacking apparatus according to the present invention, FIG. 2 is an explanatory view of a sheet conveying apparatus incorporated in the apparatus of FIG. 1, and FIG. 3 is an explanatory view of a planar structure of FIG. . Therefore, the sheet stacking apparatus according to the present invention is connected to, for example, a sheet discharge port of the image forming apparatus, and constitutes an image forming system for stacking sheets discharged from the image forming apparatus.

[Configuration of Image Forming Apparatus]
An example of such an image forming apparatus is shown in FIG. 1 and will be described. The image forming apparatus A shown in FIG. 1 sends a sheet from the sheet feeding unit 1 to the printing unit 2, prints the sheet on the printing unit 2, and then carries the sheet out from the main body discharge port 3. The sheet feeding unit 1 stores sheets of a plurality of sizes in sheet feeding cassettes 1 a and 1 b, and separates designated sheets one by one and feeds them to the printing unit 2. The printing unit 2 includes, for example, an electrostatic drum 4, a print head (laser light emitting device) 5 and a developing device 6 disposed around the electrostatic drum 4, a transfer charger 7, and a fixing device 8. An electrostatic latent image is formed by the device 5, toner is adhered to the image by the developing device 6, an image is transferred onto the sheet by the transfer charger 7, and heat fixing is performed by the fixing device 8. The sheets on which images are formed in this way are sequentially carried out from the main body discharge port 3. 9 is a circulation path, which is a double-sided printing path in which a sheet printed on the front surface from the fixing device 8 is reversed and fed to the printing unit 2 and printed on the back surface of the sheet. The sheet printed on both sides in this way is turned upside down by the switchback path 10 and then carried out from the main body discharge port 3.

  11 is an image reading apparatus, which scans a document sheet set on a platen 12 with a scanning unit 13 and electrically reads it with a photoelectric conversion element (not shown). The image data is digitally processed by an image processing unit, for example, and then transferred to the data storage unit 14 to send an image signal to the laser emitter 5. 15 is a document feeder, which is a feeder device that feeds document sheets stored in the stacker 16 to the platen 12.

[Configuration of Sheet Accumulator]
The sheet stacking apparatus B connected to the image forming apparatus A as described above will be described. The illustrated sheet stacking apparatus B is provided with a carry-in path 22 having a sheet carry-in port 21 in an appropriately shaped housing 20, and this sheet carry-in port 21 is provided at a position connected to the main body discharge port 3 of the image forming apparatus A. It has been. Further, a discharge port 23 is provided at the downstream end of the carry-in path 22, and a discharge unit 24 that conveys the sheet toward the discharge port 23 is disposed. The paper discharge means 24 is composed of a pair of rollers, a belt and the like that are in pressure contact with each other. The illustrated one includes a driving roller 24a and an idle belt 24b pressed against the driving roller 24a, and a conveyance motor M1 (not shown) is connected to the driving roller 24a.

[Configuration of stack tray (see FIGS. 2 and 4)]
A stack tray (tray means; hereinafter the same) 25 is disposed with a step D downstream of the paper discharge port 23. The stack tray 25 is constituted by a tray member for stacking and storing sheets carried out from the paper discharge port 23. The illustrated one is attached to the apparatus frame 26 in a shape in which the maximum size sheet can be placed in a substantially horizontal posture. It has been. The stack tray 25 may be fixedly attached to the apparatus frame, but is configured to move up and down in accordance with the stacking amount when stacking large capacity sheets. The illustrated one is configured separately from the following lifting arms 31a and 31b that move the stack tray 25 up and down, and the tray on which the sheets are stacked can be carried out of the apparatus in a pallet shape.

[Tray lifting means (see FIG. 4)]
As shown in FIG. 4, the tray lifting / lowering means 31 for mounting the stack tray 25 is composed of fork-like lifting arms 31a and 31b (fork members; the same applies hereinafter) mounted on the apparatus frame 26 so as to be movable up and down. . The elevating arms 31a and 31b are provided with guide rails 32a and 32b on the apparatus frame 26, and are guided along the guide rails in the stacking direction (vertical direction in FIG. 4) so as to be movable up and down. The elevating arms 31a and 31b are suspended by a pulling member 37 such as a wire or belt that is stretched around a suspension pulley 36 fixed to the apparatus frame 26. The pulling wire (traction member) 37 shown in the figure is connected to a take-up pulley 38. ing. A lifting motor M3 is connected to the winding pulley 38. Accordingly, the lifting arms 31a and 31b are supported by the guide rails 32a and 32b of the apparatus frame 26 and are moved up and down by the lifting motor M3. The stack tray 25 is mounted on the lifting arms 31a and 31b and is moved up and down according to the stacking amount below the paper discharge port 23. As shown in FIG. 1, the apparatus frame 26 is provided with a rear end regulating member 26a that abuts and regulates the rear end of the sheets accumulated on the tray 25.

[Tray lifting control]
The lift arms 31a and 31b are provided with an upper limit position sensor Sp2 for detecting the upper limit position, a maximum stack position sensor Sp3 for detecting the maximum stack position, and a lower limit position sensor Sp4 for detecting the lower limit position. The control means 70 of the lifting motor M3, which will be described later, moves the lifting arms 31a and 31b up and down by rotationally driving the lifting motor M3 in response to the paper level sensor Sp1 and the detection signals of the sensors.

[Configuration of sheet conveying means]
Above the stack tray 25, a sheet conveying means 27 for guiding the sheet from the sheet discharge outlet 23 to the front end side of the tray (left side in FIG. 2) is disposed. This sheet conveying means 27 is for grasping the leading end of the sheet from the discharge outlet 23 and forcibly pulling it out to the leading end side of the tray. With this, when the sheet is naturally dropped from the discharge outlet 23 to the stack tray 25 and stored. Thus, the time required for storing the sheet from the sheet discharge port onto the tray means can be shortened, and at the same time, the sheet can be stored neatly without disturbing the posture of the sheet.

  The sheet conveying means 27 includes a nip means 28 that moves from the paper discharge port (tray rear end side) 23 to the front end side of the tray, and a belt means 29 that carries the nip means 28. The belt means 29 is constituted by a loop-shaped belt member extending from the sheet discharge outlet 23 to the tray front end side, and a nip means 28 for nipping and gripping the sheet front end is integrally attached to the belt member. The present invention is characterized in that the belt means 29 is constituted by a first belt means 29A and a second belt means 29B, and the nip means 28A and 28B are provided in the respective belt means. This is characterized in that the long sheet SL having a long conveying distance from the paper discharge port 23 is conveyed by the first belt means 29A, and the short sheet SM having a short conveying distance is conveyed by the second belt means 29B to the front end side of the tray. . The configuration will be described below.

  Details of the sheet conveying means 27 are shown in FIGS. As shown in FIG. 2, the first belt means 29A and the second belt means 29B are arranged above the stack tray 25. In the first belt means 29A, a belt member is looped between a pair of pulleys PA1 and PA2, and similarly, a second belt means 29B is looped between the pulleys PB1 and PB2. The pulleys PA2 and PB2 (driven side) located on the paper discharge port side are supported by the same rotating shaft 30c, the other pulley PA1 (driving side) is on the rotating shaft 30a, and the pulley PB1 (driving side) is on the rotating shaft 30b. It is supported. Each of the rotary shafts 30a, 30b, and 30c is rotatably supported between the side frames 26x and 26y (see FIG. 3) of the apparatus frame 26. As shown in FIG. 3, two first belt means 29A are arranged with a left-right interval in the sheet plane direction to be conveyed, and second belt means 29B are arranged in parallel on the same plane at the center. Yes. That is, the first and second belt means 29A and 29B are arranged side by side so that the lower belt surface facing the stack tray 25 conveys the sheet on the same plane.

  The first belt means 29A and the second belt means 29B are configured to be longer than the lengths in the conveyance direction of the maximum size sheet of each of the long sheet SL and the short sheet SM that are divided in advance, for example, into two. For example, when the long sheet SL is set to JIS standards A3 and B4 and the short sheet SM is set to A4 and B5, the distance between the pulleys PA1 and PA2 of the first belt means 29A is the length in the conveyance direction of the A3 size sheet ( The distance between the pulleys PB1 and PB2 of the second belt means 29B is set slightly longer than the length in the conveying direction of the A4 size sheet.

[Configuration of belt driving means (see FIGS. 2 and 3)]
The first and second belt means 29A and 29B are selectively driven to rotate by a belt drive motor M2. As shown in FIG. 3, a belt drive motor M2 is attached to the side frame 26x of the apparatus frame, and the rotary shafts 30a and 30b are connected to the belt drive motor M2 by transmission belts V1 and V2. A one-way clutch (not shown) is built in the rotation shaft of the belt drive motor M2 so that the transmission belt V1 rotates in the forward direction and the transmission belt V2 rotates in the arrow direction in the reverse rotation.

[Refer to Fig. 10 for the configuration of the nip means]
The first belt means 29A and the second belt means 29B are provided with nip means 28A and 28B as follows. The nip means 28 is composed of a gripper member gr that grips the leading edge of the sheet, and is arranged at least one on the first and second belt means 29A and 29B. The gripper member gr has a nip piece gr1 that engages with the leading end of the sheet so as to grip the leading end of the sheet from the discharging outlet 23 and transfer it to the unloading position Ep on the leading end side of the tray. Each belt means 29 is equipped to move at the same speed.
For example, FIGS. 10A and 10B show different structures of the gripper member gr. The gripper member gr shown in FIG. 5A is supported by a mounting seat gr2 fixed to a belt member (the above-described first and second belt means) 29 with a pin gr3, and a nip piece gr1 is pressed against the belt surface by a spring gr4. It is configured as follows. The gripper member gr is made of a flexible material such as rubber or synthetic resin that is rich in elasticity. In addition, the gripper member gr can be molded integrally with the mounting seat gr2 so that the tip nip piece gr1 is in elastic contact with the belt surface. In this case, synthetic rubber, synthetic resin, etc. with high repeated bending strength are used. Is used. Therefore, the gripper member gr is fixed to the belt member 29 and has an elastic force for gripping the leading end of the sheet.

  In the gripper member gr shown in FIG. 10B, a gripper mounting recess gr5 is provided in the belt member 29, and a base end portion of the gripper member gr is supported by a shaft pin gr6 in the recess gr5. A piece gr1 is provided. The gripper member gr always acts in the direction in which the urging spring gr7 presses the nip piece gr1 against the belt surface.

As described above, the gripper member gr configured so that the tip nip piece gr1 has an elastic force is disposed at a predetermined interval at one or a plurality of locations on the first belt means 29A and the second belt means 29B. When the gripper member gr is disposed at one place, after the sheet preceded by the sheet from the paper discharge port 23 is conveyed to the front end side of the tray, the gripper member gr is moved until the subsequent sheet front end reaches the paper discharge port 23. It is necessary to make one round and reach the paper discharge outlet 23.
Therefore, it is arranged at one place, two places, or three places based on the interval between the sheets carried out from the paper discharge port 23 and the turning speed of the first and second belt means 29A, B. When the gripper members gr are arranged at a plurality of positions, they are arranged at intervals wider than the length in the conveyance direction of the maximum size sheet to be conveyed. That is, the nip means 28A1 and 28A2 of the first belt means 29A for transporting the long sheet SL transport the short sheet SM at intervals wider than the length in the transport direction of the maximum size sheet in the long sheet (for example, A3 size sheet). The nip means 28B1 and 28B2 of the second belt means 29B are arranged at intervals wider than the length in the conveyance direction of the maximum size sheet (for example, A4 size sheet) in the short sheet SM.

The illustrated one shows a case where the nip means 28A and 28B are arranged at two locations of the first and second belt means 29A and 29B, respectively. In the first belt means 29A, nip means 28A1 and 28A2 are arranged at belt positions that are equidistant from each other. Similarly, in the second belt means 29B, nip means 28B1 and 28B2 are arranged at belt positions at equal intervals. The arrangement intervals of the nip means 28A1, 28A2, 28B1, and 28B2 are set according to the conveyance direction length of the conveyed sheet. The sheet conveying means 27 is constituted by the first and second belt means 29A and 29B as described above for the following reason.
In other words, if the belt means 29 transported from the paper discharge port 23 is constituted by a single belt, for example, if the gripper members gr are arranged at an interval equal to the length in the transport direction of the maximum size sheet, the sheet is transported when a smaller size sheet is transported through the nip It is necessary to wait at the paper discharge port 23 to wait for the gripper member gr to move to the end of the paper discharge port, or to increase the interval between successive sheets. Therefore, when carrying out various types of sheets with different sizes, the productivity for carrying out the sheets from the paper discharge port to the carry-out position is set to the conveyance time of the maximum size sheet, and when the sheets of smaller sizes are continuously carried out, The paper discharge productivity is inferior.

[Configuration of tip regulating means (see FIGS. 2 and 8)]
On the other hand, on the upper side of the stack tray 25, the leading edge for dropping and storing the sheet nipped and conveyed by the first and second belt members 29A and 29B at a predetermined position (hereinafter referred to as “unloading position”) Ep on the tray. A regulating means 33 is arranged. The leading edge restricting means 33 includes stopper pieces 33A and 33B protruding into the sheet conveying path 21 so that the leading edges of the sheets conveyed by the first and second belt means 29A and 29B abut against the gripper member gr. . The leading edge regulating means 33 is attached to the apparatus frame 26 so as to be movable in the left-right direction in FIG. Therefore, the side frames 26x and 26y of the apparatus frame 26 are provided with a bottom plate plate 26z, and a stopper unit 34 is supported on the bottom plate plate 26z so as to be movable in the left-right direction in FIG. That is, a guide rail (not shown) is provided on the bottom plate plate 26z, and the stopper unit 34 is fitted and supported on the guide rail. A stopper moving motor M4 is mounted on the bottom plate plate 26z, and the stopper unit 34 is moved by this stopper moving motor M4.

[Configuration of first and second stopper pieces]
In the stopper unit 34, a first stopper piece 33A is suspended at the unloading position Ep1 of the first belt means 29A, and a second stopper piece 33B is suspended at the unloading position Ep2 of the second belt means 29B in the sheet conveyance locus of each belt means. It is attached to do. The second stopper piece 33B located on the upstream side in the sheet discharge direction is movably disposed between an operating position (solid line position in FIG. 2) and a standby position (chain line in FIG. 2) depending on the sheet conveyance locus. . That is, as shown in FIG. 3, the second stopper piece 33B is rotatably supported on the rotation support shaft 34a, and rotary solenoids MR (MR1 and MR2 described later) are connected to the rotation support shaft 34a. By rotating the rotary support shaft 34a by a predetermined angle by the rotary solenoid MR, the second belt means 29B moves up and down between an operating position protruding from the sheet conveyance locus and a standby position waiting from now on. Thus, the second stopper piece 33B hanging from the second belt means 29B is configured to be movable between the operating position and the standby position because the first belt means 29A is positioned upstream when the sheet is transferred. This is because the second stopper piece 33B to be retracted to the retracted position.

  The first and second stopper pieces 33A and 33B have the following configurations for jog storage for stacking sheets from the paper discharge outlet 23 on the tray means 25 by offsetting them in the front and rear directions in the paper discharge direction. As shown in FIG. 8, the first stopper piece 33A is composed of a front stopper piece St1 and a rear stopper piece St2, which are arranged at a predetermined distance (OL) in the paper discharge direction. The rear stopper piece St1 is fixed to the stopper unit 34, and the front stopper piece St2 is movable between an operating position protruding in the belt path (chain line in the figure) and a standby position retracted from the same (solid line in the figure). 34 is supported. A rack gear Pr is provided at the base end of the front stopper piece St2, and a pinion Pn that meshes with the rack gear Pr is provided on the unit side. The pinion Pn is connected to the stopper motor MS and moves up and down the stopper piece St2.

  On the other hand, the second stopper piece 33B is rotatably supported on the rotation support shaft 34a provided on the stopper unit 34 as described above, and the rotary support shaft 34a is provided with a rotary solenoid MR. Therefore, the second stopper piece 33B is also composed of a rear stopper piece St1 and a front stopper piece St2, which are arranged at a predetermined distance (OL) in the paper discharge direction (see FIG. 8). The rear stopper St1 is moved from the operating position to the retracted position by the rotary solenoid MR1, and the front stopper piece St2 is moved from the operating position to the retracted position by the rotary solenoid MR2.

  In this configuration, the control means 70 (not shown) operates the rotary solenoids MR1 and MR2 to operate the second stopper piece 33B (rear stopper) when a long sheet is conveyed from the paper discharge port 23 as will be described later. The piece St1 and the front stopper piece St2) are moved to the retracted position. Then, the first belt means 29A is driven to transfer the sheet leading end to the tray leading end side. At this time, the control means 70 determines whether the front stopper piece St is positioned at the operating position or the retracted position based on an instruction signal from the image forming apparatus. When the front stopper piece St2 is positioned at the operating position, the front end of the sheet is abutted against the front stopper piece St2, and when the front stopper piece St2 is positioned at the retracted position, the front end of the sheet is abutted against the rear stopper piece St1.

  Similarly, in the case of transporting the short sheet SM from the sheet discharge port 23, the control means 70 moves the second stopper means 33B by placing the rear stopper piece St1 in the operating position and the front stopper piece St2 in the retracted position. When driven, the leading edge of the sheet is regulated against abutment by the rear stopper piece St1, and when the front stopper piece St2 is positioned at the operating position, the leading edge of the sheet is regulated against abutting by the front stopper piece St2. Accordingly, both the long sheet and the short sheet are sorted and stored by changing a predetermined amount (OL) position before and after the discharge direction on the stack tray in accordance with the sorting signal from the image forming apparatus A.

[Seat-side alignment means (see FIG. 9)]
As described above, the sheet from the paper discharge port 23 is guided to the front end side of the tray by the first and second belt means 29A and 29B. When the front end of the sheet reaches the front end restricting means 33, it comes into contact with it and leaves the nip means 28. . At this time, the rear end of the sheet is detached from the sheet discharge means 24 of the sheet discharge outlet 23, and the sheet is dropped and stored on the stack tray 25. Sheet side regulating means 54 for correcting the posture in the width direction of the sheets stacked on the stack tray 25 is arranged as follows. The seat side regulating means 54 includes a pair of alignment plates 54a and 54b on the left and right side edges (front and rear in FIG. 2) of the seat. As shown in FIG. 2, the rear side alignment plate 54 b and the front side alignment plate 54 a that regulate the sheet side edge on the back side of the apparatus are arranged so as to hang downward from the upper side of the tray 25. The alignment plates 54a and 54b (hereinafter collectively referred to as “alignment plate 54”) are supported by the shaft member 54c and moved in the left-right direction in FIG.

  The illustrated alignment plate 54 is freely movable to an engagement position X (see FIG. 9) that engages with the sheet side edge, a standby position Y that is slightly separated from the sheet side edge, and a retracted position Z that is sufficiently separated from the sheet side edge. The shaft member 54c is fitted and supported. A pair of left and right shift levers 56a and 56b connected to the width adjusting motor M5 are connected to the alignment plate 54, and both levers are engaged with a pinion M5p of the width adjusting motor M5. Accordingly, the alignment plate 54 moves in accordance with the width size of the sheet by the rotation of the pinion M5p. That is, the rear side and front side alignment plates 54 are moved to a position suitable for the sheet width size by rotation of the width adjusting motor M5, and at this position, the standby position Y slightly separated from the sheet side edge is engaged with the sheet side edge. It reciprocates by forward / reverse rotation of the pinion M5p with the engaging position (operating position) X.

[Seat trailing edge pressing means (see FIG. 11)]
A sheet trailing edge pressing means 58 is provided for hitting the trailing edge of the sheet to the tray side in the process of dropping the sheet onto the stack tray 25 together with the sheet side alignment means 54. As shown in FIG. 11, the sheet trailing edge pressing means 58 is arranged on the upper downstream side of the sheet discharge outlet 23, and a flat plate-like hitting piece 58a for hitting the sheet trailing edge from the sheet discharge outlet 23 to the lower stack tray 25. It has. The hit piece 58 a is inserted into a support cylinder 59 fixed to the apparatus frame 26 and connected to the drive lever 60. A drive motor M6 is connected to the drive lever 60, and the drive lever 60 swings at a predetermined angle by forward / reverse rotation of the motor. A hitting piece 58a connected to the drive lever 60 moves up and down between the solid line and the chain line in FIG. Will move. Accordingly, the sheet that is separated from the paper discharge port 23b and is transported toward the front end regulating means 33 by the aligning rotating body 29a is knocked down by the tapping piece 58a and stored on the tray. . This is to prevent the leading edge of the sheet sent subsequent to the sheet discharge outlet and the trailing edge of the preceding preceding sheet from dropping from interfering with each other.

[Paper holding means (see FIGS. 5, 6 and 7)]
The present invention is characterized in that the paper pressing means 61 for pressing and holding the sheets stacked on the stack tray 25 in the above-described configuration has the following configuration. The details of the paper pressing means 61 are shown in FIG. 5, but a paper touch piece (sheet pressing piece; pressing and holding both side edges of the sheets stacked on the stack tray 25 (right and left edges in the direction perpendicular to the paper discharge; the same applies hereinafter)). The same applies below) 62a and 62b. As shown in FIG. 5 (b), the pair of left and right paper contact pieces 62a and 62b are moved from the rear edge of the sheet on the tray to the center of the sheet by the offset amount OL and outward from the sheet end surface. It is configured to be movable between a retreat position that is far away. For this reason, the paper pressing means 61 is composed of arm members 63a and 63b having paper touch pieces 62a and 62b at the tips, and the base end portions of the arm members 63a and 63b are connected to a cylindrical shaft member 65 provided in the apparatus frame 26. It is pivotably fitted.

  That is, the arm member provided with the paper touch piece is fitted and supported by the shaft member of the apparatus frame so as to be able to move up and down and rotate, and can be rotated in the same direction as the paper surface of the uppermost sheet on the tray. It moves up and down and presses the top sheet on the tray to hold the sheet bundle. Although not shown, a biasing spring is provided between the paper touch pieces 62a and 62b and the arm members 63a and 63b so as to always bias the paper touch pieces 62a and 62b to the uppermost sheet side. The shaft member 65 is formed with an inclined cam groove 64a shown in FIGS. 6A and 6C, and a cam follower pin 64b (hereinafter referred to as "cam pin") that engages with the cam groove 64a is an arm member. It is provided on the side. Accordingly, as shown in FIG. 5C, the cam pin 64b moves up and down in the vertical direction in accordance with the height of the paper surface at the operating position, and then moves to the retracted position through the rotation region. The arm member 63 integrated with the cam pin 64b and the paper touch pieces 62a and 62b also perform the same movement.

  When the cam groove 64a is moved from the retracted position to the operating position with respect to the paper surface of the uppermost sheet on the tray, the cam groove 64a is lowered to the paper surface after rotating from the outside of the paper surface to the paper surface, or (2). The cam curve is configured to either descend on the paper surface while rotating in the paper surface direction from the outside of the paper surface, or (3) rotate in the paper surface direction after descending on the paper surface.

[Configuration of shift means]
Shifting means (shift motor M7) for moving the paper touch pieces 62a, 62b between the operating position and the retracted position is connected to the arm members 63a, 63b. That is, a flange-like passive portion 63x is provided at the base end portion of the arm member, and a transmission lever 66 that moves the arm member up and down is connected to the passive portion 63x. As shown in FIG. 5, a drive rotary shaft 67 is disposed at the rear end of the sheet on the tray 25, and a shift motor M 6 is connected to the rotary shaft 67. Spa shown is a position sensor. Accordingly, when the shift motor M6 is rotated forward and backward, the rotary shaft 67 rotates, and the transmission lever 66 attached thereto moves up and down the passive portion 63x of the arm members 63a and 63b in the vertical direction in FIG.
As a result, the arm members 63a and 63b move between the retracted position and the operating position. That is, when the motor M6 is driven in the direction indicated by the arrow in FIG. 5 (a), the transmission lever 66 pulls the paper touch piece 62a upward. At this time, the cam pin 64b of the paper touch piece 62a is rotated approximately 90 degrees by the inclined cam groove 64a, and at the same time the paper touch piece 62a moves upward from the operating position, the paper touch piece 62a swings about 90 degrees to move to the retracted position (same as above). Move to the chain line.

[Seat rear edge locking means]
The sheets stacked on the stack tray 25 are supported by pressing the uppermost sheet by the paper pressing means 61 described above. A sheet rear end locking means 68 for locking the sheet rear end simultaneously with the paper pressing means 61 is provided as follows. The tray elevating arms 31a and 31b are provided with a rear end regulating member 26a for regulating the rear end of the sheets stacked on the tray (see FIG. 7). A sheet rear end locking means 68 for locking the rear end of the sheet regulated by the rear end regulating member 26a is disposed on the apparatus frame 26 as shown in FIG. The locking means 68 includes a locking claw 68a that engages with the uppermost sheet on the tray, and is attached to the shaft 68b so as to be swingable in the direction of the arrow shown. This is to prevent the trailing edge of the sheet from being pushed up when the above-described paper pressing means 61 moves from the operating position toward the retracted position (when the sheet pressing means 61 is detached from the uppermost sheet).

  Therefore, the locking means 68 is always biased to a position where it engages with the sheet by the spring 68c, and moves to a retracted position separated from the sheet by the solenoid SL against this spring. And it moves between the position (actuation position) where the locking means 68 is engaged with the uppermost sheet by the signal from the control means and the position retracted (retraction position). The locking means 68 locks the uppermost sheet on the tray so as to have a time difference from the paper pressing means 61 as will be described later.

[Description of paper ejection operation]
A sheet discharge operation of the sheet stacking apparatus B configured as described above will be described.
"Initial setting"
The image forming apparatus A is provided with a control panel (not shown), from which a sheet size to be printed and other image forming conditions are set (“image forming mode setting” St001). Then, the control CPU provided in the image forming apparatus A sends the designated sheet from the sheet feeding cassettes 1a and 1b to the electrostatic drum 4 based on the set conditions, and forms a predetermined image on the sheet. The sheet on which the image is formed in this manner is carried out from the paper discharge port 3. Therefore, the control unit 70 (not shown) of the sheet stacking apparatus B receives information on the size type of the sheet on which the image is formed and the sheet posture (whether the posture is the vertical posture or the horizontal posture) from the image forming apparatus A. Based on this information, the control means 70 determines whether the sheet from the paper discharge port 23 is conveyed by the first belt means 29A or the second belt means 29B. This determination is made by comparing whether or not it is greater than or less than a predetermined sheet size. The first belt means 29A conveys the sheet from the sheet discharge outlet 23 to the front end side of the tray as follows in the case of a long sheet of a predetermined size or larger and the second belt means 29B in the case of a short sheet of a predetermined size or smaller.

[For long sheet SL]
When the sheet carried out from the image forming apparatus A is a long sheet SL, the control unit 70 moves the nip unit 28B of the second belt unit 29B to the retracted position before the sheet reaches the sheet discharge port 23. The retraction position of the nip means 28B is set to the illustrated position away from the long sheet movement locus shown in FIG. In order to determine this position, a home position sensor Hp2 for detecting the nip means 28B of the second belt means 29B is disposed at the position shown in FIG. Accordingly, the control means 70 drives the belt drive motor M2, the second belt home position sensor Hp2 detects the nip means 28B, rotates the motor M2 by a predetermined angle based on the detection signal of this sensor, and the nip means 28B When it is positioned at the standby position 12 (b), the motor M2 is stopped.

  Next, the control means 70 starts to rotate the drive motor M1 to rotate the paper discharge means 24. The belt drive motor M2 is rotated in the reverse direction before and after the start of the drive motor M1. With this rotation, the first belt means 29A rotates clockwise in FIG. 12C, and when the nip means 28A reaches the illustrated position (home position), this is detected by the home position sensor Hp1, and the belt drive motor M2 is detected. Stop. In this state, one of the nip means 28A attached to the first belt means 29A stops and waits while facing one of the paper discharge ports 23.

  The control means 70 operates the rotary solenoid MR to retract the second stopper piece 33B from the long sheet movement locus to the retracted position before and after the nip means 28A is made to wait at the sheet discharge port 23. At the same time, the control means 70 activates the stopper moving motor M4 to move the first stopper piece 33A to the carry-out position Ep1 corresponding to the sheet size. In this state, the state becomes as shown in FIG.

"Sheet transfer operation"
Next, from the detection signal that the sheet discharge sensor S1 of the sheet discharge port detects the leading edge of the sheet, after the expected time that the sheet leading edge is nipped by the nip unit 28A of the sheet discharge port 23, the control unit 70 turns the belt drive motor M2 to the clock. The first belt means 29A is moved in the direction of the arrow. The belt conveyance speed is set to the same speed as that of the paper discharge means 24. Therefore, as shown in FIG. 12C, the sheet is transferred to the front end side of the tray by the first belt means 29A and the paper discharge means 24, and the front end of the sheet hits the front end restricting means 33A. In this state, the sheet separates from the first belt unit 29A and the paper discharge unit 24 and falls onto the stack tray 25.

"Retraction operation of paper holding member"
The control means 70 moves the paper contact pieces 62a and 62b of the paper pressing means 61 from the operating position to the retracted position after a predetermined time from the rear end detection signal of the paper discharge sensor S1 after the rear end of the sheet is separated from the paper discharge means 24. Moving. The movement to the retreat position is performed by the shift motor M7 to move the paper touch piece 62 from the operation position in the solid line state in FIG.

"Seat trailing edge pressing means operation"
Next, the control means 70 rotates the drive motor M6 of the sheet trailing edge pressing means 58 and swings the drive lever 60 clockwise in FIG. 11 before and after the movement of the paper pressing means 61 to the retracted position. Then, the hitting piece 58a vigorously hits the rear end of the sheet downward, and accumulates the rear end of the sheet on the tray.

"Retraction operation of the sheet rear edge locking means"
The control means 70 operates the above-described sheet trailing edge pressing means 58 to move the sheet trailing edge locking means 68 from the operating position to the retracted position immediately before the sheet falls on the tray from the sheet discharge outlet. This movement operates the solenoid SL (energized state) to move the locking claw 68a against the spring 68c.

"Seat-side alignment operation"
The control means 70 activates the width adjusting motor M4 at the timing when the sheets are stored on the tray, and moves the alignment plates 54a and 54b from the standby position to the operating position, thereby aligning the sheets stacked on the tray. To do.

"Return operation of paper holding means"
Next, the control means 70 drives the vertical motor M6 to return the paper pressing means 61 at the standby position to the operating position on the tray (state shown in FIG. 6A). After the return of the paper pressing means 61 to the operating position, the control means 70 operates the solenoid SL (returns to the non-energized state) to lock the sheet trailing edge locking means 68 with the trailing edge of the uppermost sheet. Return to position.

  By repeating the above-described operation, the sheets sent to the paper discharge outlet 23 are stacked and stored on the stack tray 25. When the sheet level sensor Sp1 detects a predetermined amount of sheet stacking, the control means 70 moves down the lifting arms 31a and 31b by a certain amount. When the elevating arms 31a and 31b are lowered to the position of the maximum loading capacity set in advance, the control means 70 determines that it is full. At the time of full detection or in response to a job end signal from the image forming apparatus A, the control unit 70 moves the stack tray 25 to the lowermost sheet take-out position to prepare for taking out the sheets from the apparatus.

[In case of short sheet SM]
When the sheet carried out from the image forming apparatus A is a short sheet SM, the control unit 70 moves the nip unit 28A of the first belt unit 29A to the retracted position before the sheet reaches the sheet discharge port 23. The retracted position of the nip means 28A is set to the illustrated position away from the short sheet movement locus shown in FIG. In order to determine this position, a home position sensor Hp1 for detecting the nip means 28A of the first belt means 29A is arranged at the position shown in FIG. Accordingly, the control means 70 drives the belt drive motor M2, the first belt home position sensor Hp1 detects the nip means 28A, rotates the motor M2 by a predetermined angle based on the detection signal of this sensor, and the nip means 28A is shown in FIG. When it is positioned at the standby position 13 (b), the motor M2 is stopped.

  Next, the control means 70 starts to rotate the drive motor M1 to rotate the paper discharge means 24. The belt drive motor M2 is rotated in the reverse direction before and after the start of the drive motor M1. With this rotation, the second belt means 29B rotates clockwise in FIG. 13C. When the nip means 28B reaches the illustrated position (home position), this is detected by the home position sensor Hp2, and the belt drive motor M2 is detected. Stop. In this state, one of the nip means 28B attached to the first belt means 29A stops and waits while facing one of the paper discharge ports 23. Subsequent operations are the same as those of the above-described long sheet SL, and thus description thereof is omitted.

1 is an overall configuration diagram of an image forming system including a sheet stacking apparatus according to the present invention. FIG. 2 is an explanatory diagram of a sheet stacking apparatus incorporated in the apparatus of FIG. 1. Plane explanatory drawing of the apparatus of FIG. Explanatory drawing of the tray raising / lowering mechanism in the apparatus of FIG. FIG. 3 is an explanatory diagram of a structure of a paper pressing unit in the apparatus of FIG. 2, (a) is a perspective view thereof, and (b) is an explanatory diagram of a planar structure. FIGS. 3A and 3B are explanatory diagrams of the structure of the paper pressing means in the apparatus of FIG. 2, wherein FIG. 3A is an explanatory diagram of an operating state, FIG. 2B is an explanatory diagram of a retracted state, and FIG. Structure explanatory drawing of the sheet rear end locking means in the apparatus of FIG. Structure explanatory drawing of the front-end | tip control means in the apparatus of FIG. FIG. 3 is an explanatory diagram of the structure of side alignment means in the apparatus of FIG. 2. It is explanatory drawing which shows the structure of the nip means in the apparatus of FIG. 2, (a) and (b) show the structure of a different gripper member, respectively. FIG. 3 is an explanatory diagram of the structure of sheet trailing edge pressing means in the apparatus of FIG. 2. FIGS. 3A and 3B are explanatory diagrams of a discharge state of a long sheet SL in the apparatus of FIG. 2, where FIG. 3A is an explanatory diagram of an initial operation, FIG. 2B is an explanatory diagram of an initial discharge state, and FIG. The state explanatory drawing after. FIGS. 3A and 3B are explanatory diagrams of a discharge state of a short sheet SM in the apparatus of FIG. 2, where FIG. 3A is an explanatory diagram of an initial operation, FIG. 2B is an explanatory diagram of an initial discharge state, and FIG. FIG. Explanatory drawing of the prior art relevant to this invention.

Explanation of symbols

21 sheet carry-in port 22 carry-in path 23 paper discharge port 24 paper discharge unit 24a drive roller 24b idle belt 25 stack tray 26 apparatus frame 27 sheet transport unit 28A, 28B nip unit 29 belt unit 29A first belt unit 29B second belt unit M2 Belt drive motor 33A End restricting means 33B (for the first belt means) End restricting means 31a, 33b (for the second belt means) Tray lift arm 34 Stopper unit M4 Stopper moving motor SL Long sheet SM Short sheet V1, V2 Transmission belt A Image forming apparatus B Sheet stacking apparatus 61 Paper pressing means 61a, 61b Paper touch pieces 63a, 63b Arm member 64a Cam groove 64b Cam pin (cam follower)
M6 shift means

Claims (9)

A paper discharge port for sequentially carrying out the sheets;
Tray means arranged to form a step below the paper discharge port and stacking and storing sheets from the paper discharge port;
A paper pressing means for pressing the sheets stacked on the tray means;
Shift means for moving between an operating position where the paper pressing means is engaged with the uppermost sheet on the tray means and a retracted position retracted from the uppermost sheet;
With
The paper pressing means has a sheet pressing piece for pressing the uppermost sheet on the tray means,
When the sheet pressing piece moves between the operating position and the retracted position, a rotational trajectory that moves along the sheet direction with respect to the uppermost sheet on the tray means, and a vertical direction with respect to the sheet surface of the uppermost sheet. A sheet stacking apparatus configured to move along a movement trajectory having a vertical movement trajectory that moves in a straight line. When the sheet pressing piece moves from the retracted position to the operating position,
(1) Turned in the paper direction and then lowered on the paper surface with respect to the uppermost sheet on the tray means, or (2) lowered on the paper surface while rotating in the paper surface direction, or (3) Paper surface side The sheet stacking apparatus according to claim 1, wherein the sheet stacking apparatus is configured to rotate in a paper surface direction after being lowered. The shift means moves the paper pressing means from the operating position to the retracted position before the sheet carried out from the paper discharge port falls onto the tray means, and then the sheets are accumulated on the tray means. The sheet stacking apparatus according to claim 1, wherein the sheet stacking apparatus is moved from the retracted position to the operating position. The tray means is arranged to stack sheets in a substantially horizontal position;
2. The sheet stacking apparatus according to claim 1, wherein the sheet pressing piece is configured to rotate in a horizontal direction from the retracted position, and then descend in a vertical direction to move to the operating position. The sheet pressing piece is rotatably supported at its base end by a substantially cylindrical shaft member,
The shaft member and the base end portion of the sheet pressing piece are formed such that a cam groove is fitted on one side and a cam follower is fitted on the other,
The cam groove is formed to rotate within a predetermined angle range when the sheet pressing piece moves up and down, and the shift means transmits the drive so that the sheet pressing piece moves up and down. The sheet stacking apparatus according to any one of 1 to 4. The paper pressing means is
Having first and second sheet pressing pieces for pressing both side edges of the uppermost sheet in the paper discharge direction on the tray means;
The tray means is provided with a sheet end locking member that presses the edge in the sheet discharge direction of the uppermost sheet,
2. The sheet stacking apparatus according to claim 1, wherein the sheet end locking member is retracted from the tray means when the sheet is stored. The tray means is provided with a reference position for aligning the front and rear ends of the sheet from the discharge outlet in the discharge direction and a jog means for offsetting the sheet from the discharge outlet by a predetermined amount in the front and rear directions.
The sheet pressing piece of the paper pressing unit is disposed so as to press the sheet at a position away from the reference position from the offset amount. Sheet stacking device. The jog means may be (1) a restricting position moving means for moving a front end restricting means for abutting and restricting the front end of the sheet from the paper discharge port to move back and forth in the paper discharge direction, The sheet accumulating apparatus according to claim 7, comprising a tray position moving means that moves to the right. An image forming apparatus including an image forming unit that forms an image on a sheet;
A sheet stacking device which is disposed at a paper discharge port of the image forming apparatus and sequentially stacks and stores sheets on which images are formed on a tray unit;
An image forming system, wherein the sheet stacking apparatus has the configuration according to any one of claims 1 to 8.

Images