JP2008133106A - Sheet stacking device and image forming system equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve sheet discharging productivity by using a gripper for carrying sheets along their moving track corresponding to a long/short sheet size when using a nip means for gripping the sheets at their front ends and carrying them from a sheet discharge port to the front end of a tray. <P>SOLUTION: This sheet stacking device comprises the sheet discharge port 23 out of which the sheets are carried in sequence, a tray means 25 arranged on the downstream side of the sheet discharge port, and a sheet transfer means 27 for transferring the sheets from the sheet discharge port to the front end of the tray. The sheet transfer means has the nip means 28 for holding the sheets at their front ends, and a looped belt means 29 to be moved from the sheet discharge port along a sheet discharging direction. The belt means consists of a first belt means 29A for transferring short sheets of predetermined length or smaller from the sheet discharge port and a second belt means 29B for transferring long sheets of predetermined length or greater therefrom. A driving means M2 for each belt means makes the nip means for the belt means on the non-operation side retreat at a retreat position outside a sheet transfer track of the belt means on the operation side with the selective operation of the first or second belt means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet stacking apparatus in an image forming apparatus such as a copying machine, a printer, a facsimile apparatus, or a bill handling apparatus, and the sheet is transferred to a predetermined position on the downstream side by a conveying means such as a roller at a high speed on a tray. The present invention relates to an improvement of a sheet carrying out mechanism.

  2. Description of the Related Art In general, a sheet stacking apparatus that stacks and stores sheets such as paper is used in a wide range of fields such as various image forming apparatuses, printing apparatuses, and bill handling apparatuses. As a mechanism for conveying the sheet from the sheet discharge port to the leading end of the tray unit, for example, a mechanism that nips and conveys the sheet with a pair of rollers or conveys the sheet with a conveyor belt is often used. Recently, it has been particularly demanded to increase the speed of processing apparatuses such as image forming apparatuses and handle various sheets. When the sheet is conveyed while being nipped in this way, a guide guide for conveying the sheet downstream in a predetermined posture is required. Conventionally, a path is formed by the conveyance guide, and the sheet is conveyed at high speed in this path. Is frequently used. However, since the conveyance guide cannot be disposed above the tray means, the sheet is discharged from the sheet discharge outlet at a high speed and stored in a falling manner.

  In such a case, a conventionally known first method is a structure in which a guide member is suspended from a paper discharge port in a trap shape. In this case, if the sheet is discharged at a high speed, the curled sheet may be caught between the tray and is not suitable for high-speed carry-out of the sheet. A conventionally known second method has been proposed in which a vacuum belt is disposed above the tray from the paper discharge port, and the front end of the sheet is guided to a predetermined position on the tray by the vacuum belt and discharged. When such a vacuum mechanism is employed, there is a known problem that the apparatus becomes large and expensive.

Therefore, as a relatively simple method, for example, in Patent Documents 1 and 2, a belt is disposed above the tray, and a clip-like gripper that nip-supports the leading end of the sheet is provided on the belt. A structure has been proposed in which the sheet is conveyed to the front end side of the tray, the nip is released at the front end position, and the sheet is dropped onto the tray. For example, a belt member is stretched endlessly above the tray, and a plurality of grippers are integrally formed on the belt at a predetermined interval. The leading end of the sheet carried out from the paper discharge port is inserted into the gripper and then gripped, and then the sheet is carried out. The belt is driven to rotate at the same speed as the speed. There has been proposed a structure in which when the leading edge of the sheet reaches a predetermined position on the tray, the leading edge of the sheet is brought into contact with the leading edge regulating means and is separated from the gripper and accommodated on the tray.
JP 2003-341908 A JP 2006-124052 A

  As described above, when the sheet is conveyed from the sheet discharge port to a predetermined position on the downstream side and stored in the tray unit, the following problems occur in the structures of Patent Documents 1 and 2 described above. As described above, when the gripper that grips the leading edge of the sheet is arranged on the belt member, a plurality of grippers are arranged at intervals longer than the length in the conveyance direction of the maximum size sheet, and after the sheet is carried onto the tray by the preceding gripper, the subsequent The gripper to be operated faces the paper discharge port. Therefore, even in the case of a small-sized sheet, it is necessary to wait for the subsequent gripper to reach the sheet discharge port, or to increase the interval between sheets that are continuously carried out. In either case, the number of sheets processed per hour is reduced. Especially when a general-purpose sheet is, for example, a JIS standard A4 horizontal size, the maximum sheet size is A3, and the subsequent gripper is simple until it reaches the discharge port. Takes twice as long to complete.

Therefore, according to the present invention, when the sheet leading edge is gripped by the nip means from the sheet discharge outlet and conveyed to the tray leading end side, the gripper carries out the sheet with a movement locus corresponding to the long and short sheet size, thereby discharging the sheet per unit time. The problem is to provide a highly productive sheet stacking apparatus.
Another object of the present invention is to provide a sheet stacking apparatus capable of stacking sheets at high speed and orderly when the sheets are carried out to tray means provided on the downstream side of the sheet discharge port.

  To achieve the above object, the present invention employs the following configuration. In the present invention, the “long sheet” refers to a sheet (one or more) whose length in the conveying direction is longer than a preset length, and the “short sheet” refers to a sheet shorter than a preset length. That is, in order to divide a plurality of sheets having different lengths into two, the length is shorter than a preset length, and the shorter sheet is referred to as a short sheet. Therefore, a sheet discharge port (23) for sequentially carrying out the sheets, a tray means (25) disposed with a step on the downstream side of the sheet discharge port, and a tray unit (25) disposed above the tray means from the sheet discharge port. A sheet transfer means (27) for transferring the sheet to the front end side of the tray. The sheet conveying means is constituted by a loop belt means (29) having a nip means (28) for holding the leading end of the sheet and moving from the paper discharge port along the sheet discharge direction. The belt means includes a first belt means (29A) for transferring a short sheet having a predetermined length or less from the discharge port and a second belt means (29B) for transferring a long sheet having a predetermined length or more, The driving means (M2) of the first and second belt means is configured such that the first and second belt means are selectively operated. The control means of the driving means retracts the nip means of the non-operating side belt means from the sheet transfer locus of the operating side belt means to the outward retreat position when selectively operating the first second belt means. Let

  A plurality of the nip means are arranged on the first and second belt means at predetermined intervals. The first and second belt means are respectively looped between pulley means arranged on the paper discharge port side and pulley means (PA, PB) arranged on the front end side in the paper discharge direction. The pulley means of the first second belt means is disposed on a common rotating shaft.

  The first and second belt means are juxtaposed in a direction perpendicular to the conveyance of the sheet from the sheet discharge port, and the long sheet and the short sheet are moved from the sheet discharge port to the front end side of the tray unit with substantially the same transfer locus. Transport. In addition, a sheet leading edge restricting means that abuts the sheet transferred by the sheet conveying means and drops onto the tray means is disposed above the tray means. The sheet leading edge restricting means is a length in the sheet conveyance direction from the sheet discharge port. The position is freely movable according to the height.

  Control means for controlling the drive means of the first second belt means drives one of the first second belt means in accordance with sheet size information from an external device installed upstream of the paper discharge port. Configure as follows.

  An image forming system according to the present invention includes an image forming apparatus that sequentially forms an image on a sheet, and a sheet stacking apparatus that stacks the image-formed sheet disposed at a paper discharge port of the image forming apparatus on a tray unit. The sheet stacking apparatus has the above-described configuration.

  The present invention provides a first belt means for transferring a short sheet of a predetermined length or less from a paper discharge outlet to a tray front end side and a long sheet of a predetermined length or more when the sheet is carried out and stored in the tray means from the paper discharge outlet. The second belt means for conveying the sheet is provided, and according to the sheet length, the first second belt means is used to transfer the sheet from the sheet discharge port to the tray leading end. Even if it is placed between the paper exit and the tray tip, the nip means has a short trajectory when short sheets are continuously carried out from the paper exit, and a long movement trajectory when long sheets are carried out. Thus, since the sheets are sequentially carried out, the sheet carrying efficiency per unit time can be remarkably improved. Further, the structure for that purpose is to arrange two long and short belt means at the paper discharge port and selectively carry out the sheet according to the sheet length, and it is very simple and its control is easy.

  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 enlarged explanatory view of a main part of the apparatus of FIG. It is. 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 6)]
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. 6)]
As shown in FIG. 6, the tray lifting 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. 6) 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. The elevating arms 31a and 31b are provided with a rear end restricting member 26a for restricting the rear end of the sheet. The rear end of the sheet from the sheet discharge outlet 23 is abutted on the tray mounted on the arm and sequentially controlled. It is designed to be stacked up.

[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.

[Configuration of 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. 4A and 4B show different gripper member gr structures. A gripper member gr shown in FIG. 6A is supported by a mounting seat gr2 fixed to a belt member (the above-described first and second belt means) 29 by a pin gr3 so that the nip piece gr1 is pressed against the belt surface by a spring gr4. It is configured. 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. 4B, 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, and a nip is provided at the distal end portion. 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 and 29B. 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 thus constituted by the first and second belt means 29A and 29B 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 5)]
On the other hand, at the upper side of the stack tray 25, the front end regulation for dropping and storing the sheet nipped and conveyed by the first second belt members 29A and 29B at a predetermined position (hereinafter referred to as “unloading position”) Ep on the tray. Means 33 are 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 first stopper piece 33A is fixed to the stopper unit 34, and the second stopper piece 33B is movable between an operating position (solid line position in FIG. 2) and a standby position (chain line in the figure) depending on the sheet conveyance locus. Has been placed. That is, the first stopper piece 33A is a fixed stopper member, and the second stopper piece 33B is a movable stopper member. As shown in FIG. 3, the second stopper piece 33B is rotatably supported by a rotation support shaft 34a, and a rotary solenoid MR is connected to the rotation support shaft 34a. Then, the rotary solenoid MR rotates the rotary support shaft 34a by a predetermined angle to move the stopper piece 33B up and down between the operating position protruding on the sheet conveyance locus of the second belt means 29B and the standby position waiting from now. 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.

[Different modes of stopper pieces (see FIG. 5B)]
The first and second stopper pieces 33A and 33B are both arranged at one place in the conveyance direction. However, in the case of jog paper discharge in which sheets are stacked with a predetermined offset (position shift) on the stack tray. The stopper piece is constructed as follows. As shown in FIG. 5B, the fixed stopper piece St1 and the movable stopper piece St2 are provided at different positions in the paper discharge direction. The fixed stopper piece St1 is fixed to the stopper unit 34, and the movable stopper piece St2 is supported so as to be movable up and down so as to protrude and retract with respect to the sheet transfer locus of the belt means (first belt means or second belt means) 29. The fixed stopper piece St1 and the movable stopper piece St2 have a predetermined distance in the sheet conveyance direction, and the movable stopper piece St2 is disposed on the upstream side. Therefore, for example, as shown in the figure, a rack gear Pr is provided at the base end of the movable stopper piece St2, and the stopper moving motor M4 is connected to a pinion Pn that meshes with the rack gear Pr. The movable stopper St2 is controlled by the stopper moving motor M4 so as to be movable up and down between an operating position where the movable stopper St2 is engaged with the sheet on the stack tray 25 and a retracted position retracted in the stopper unit 34. As a result, the sheets from the sheet discharge outlet 23 can be stacked on the stack tray 25 in a state where the sheets are offset by a predetermined interval, and the sheets can be stored in a jog manner divided into sections.

[Sheet side alignment means (see FIG. 7)]
As described above, the sheet from the sheet discharge port 23 is guided to the front end side of the tray by the first second belt means 29A and 29B, and 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. Both alignment plates 54a and 54b (hereinafter collectively referred to as “alignment plate 54”) are supported by a 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. 7) for engaging the sheet side edge, a standby position Y slightly separated from the sheet side edge, and a retracted position Z 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. 9)]
A sheet trailing edge pressing means 58 is provided for striking the trailing edge of the sheet toward the tray in the process of dropping the sheet onto the tray means 25 together with the sheet side alignment means 54. As shown in FIG. 8, the sheet trailing edge pressing means 58 is disposed on the downstream upper side of the sheet discharge outlet 23, and a flat plate-like hitting piece 58a for striking the sheet trailing edge from the sheet discharge outlet 23 to the lower tray means 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 vertically 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.

[Tray paper holding means (see FIG. 8)]
The stack tray 25 mounted on the tray lifting / lowering means 31 is provided with a paper pressing means 61 for pressing and holding the stacked sheets. The details are shown in FIG. 7, but a pair of left and right paper pressing members 61 a and 61 b (hereinafter referred to as “paper pressing member 61”) that press and hold the sheet side edge perpendicular to the paper discharge direction is applied to the sheets stacked on the stack tray 25. The sheet pressing member 61 is retracted from the tray when the sheet drops, and presses the uppermost sheet after the sheet is dropped and stored. For this reason, the illustrated paper pressing member 61 includes an arm-shaped paper touch piece 62 a and a cylinder cam 62 b, and the cylinder cam 62 b is fixed to the apparatus frame 26. The cylinder cam 62b is formed with an inclined cam groove 62c for rotating the paper touch piece 62a according to the vertical movement. The paper touch piece 62a is provided with a pin 62d that is fitted to the cylinder cam 62b and engages with the inclined cam groove, and an arm 63 connected to the vertical movement motor M7 is fitted to the paper touch piece 62a. Accordingly, when the motor M7 is driven in the direction of the arrow in FIG. 8C, the arm 63 pulls the paper touch piece 62a upward. At this time, the pin 62d of the paper touch piece 62a is rotated approximately 90 degrees by the inclined cam groove 62c of the cylinder cam 62b, and at the same time the paper touch piece 62a moves upward from the state of FIG. Move to the retreat position by swinging 90 degrees. Spa shown in the drawing is a position sensor for the paper touch piece 62a, and the position is detected with the retracted position as the home position.

[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”). 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 10 (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. 10C. 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. 10C and waits for the sheet to be carried out from the sheet discharge outlet 23.

"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. 10C, 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 means 29A and the paper discharge means 24 and falls onto the tray means 25.

"Sheet trailing edge pressing means operation and paper pressing member retraction operation"
The control means 70 moves the paper contact pieces 62a and 62b of the paper pressing means 61 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 detached from the paper discharge means 24. This movement to the retracted position is performed by moving the paper touch piece 62 to the retracted position shown in FIG. At the same time, the control means 70 rotates the drive motor M6 of the sheet trailing edge pressing means 58 to swing the drive lever 60 clockwise in FIG. 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.

"Seat-side alignment operation"
Concurrently with the stop of the aligning rotating body 29a, the control means 70 activates the width adjusting motor M4 at the timing when the sheet is stored on the tray, and moves the aligning plates 54a and 54b from the standby position to the operating position. The sheets accumulated on the tray are aligned and aligned.

"Tray paper presser return operation"
Next, the control means 70 drives the vertical motor M6 to return the holding means 61 in the standby position to the operating position on the tray (state shown in FIG. 8A).

  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 means 70 moves the tray means 25 to the lowermost sheet take-out position to prepare for taking out the sheet 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 retraction 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 at the standby position 11 (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. 11C. 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. 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. It is structure explanatory drawing of the front-end | tip control means in the apparatus of FIG. 2, (a), (b) shows each different aspect. The figure explaining the detail of the tray raising / lowering means to raise / lower a stack tray is shown. FIG. 3 is an explanatory diagram of the structure of side alignment means in the apparatus of FIG. 2. FIG. 3 is an explanatory diagram of the structure of a paper pressing unit in the apparatus of FIG. 2. 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.

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 regulating means 33B (for the first belt means) End regulating means 31a, 31b Tray lifting / lowering arm 34 Stopper unit M4 Stopper moving motor SL Long sheet SM Short sheets V1, V2 Transmission belt A Image forming apparatus B Sheet stacking apparatus

Claims (7)

A paper discharge port for sequentially carrying out the sheets;
Tray means arranged with a step on the downstream side of the paper discharge port;
A sheet transfer means disposed above the tray means for transferring a sheet from the sheet discharge outlet to the front end side of the tray;
With
The sheet transporting means comprises a loop belt means having a nip means for holding the leading edge of the sheet and moving along the sheet discharge direction from the discharge port,
The belt means includes a first belt means for transferring a short sheet having a predetermined length or less from the discharge port and a second belt means for transferring a long sheet having a predetermined length or more.
The driving means of the first and second belt means is configured such that the first and second belt means are selectively operated;
The control means of the driving means retracts the nip means of the non-operating side belt means from the sheet transfer locus of the operating side belt means to the outward retreat position when selectively operating the first second belt means. A sheet accumulating apparatus characterized in that 2. The sheet accumulating apparatus according to claim 1, wherein a plurality of the nip means are arranged at predetermined intervals on each of the first and second belt means. The first and second belt means are respectively stretched between a pulley means arranged on the paper discharge port side and a pulley means arranged on the front end side in the paper discharge direction. 3. The sheet stacking apparatus according to claim 1, wherein the pulley means is disposed on a common rotating shaft. The first and second belt means are juxtaposed in a direction perpendicular to the conveyance of the sheet from the sheet discharge port, and the long sheet and the short sheet are moved from the sheet discharge port to the front end side of the tray unit with substantially the same transfer locus. The sheet stacking apparatus according to any one of claims 1 to 3, wherein the sheet stacking apparatus is transported. Above the tray means is disposed a sheet leading edge regulating means that abuts the sheet transported by the sheet transport means and drops it onto the tray means,
5. The sheet stacking apparatus according to claim 1, wherein the sheet leading edge restricting unit is configured to be movable in accordance with the length of the sheet in the conveyance direction from the sheet discharge port. Control means for controlling the drive means of the first second belt means drives one of the first second belt means in accordance with sheet size information from an external device installed upstream of the paper discharge port. 6. The sheet stacking apparatus according to claim 1, wherein the sheet stacking apparatus is configured as described above. An image forming apparatus for sequentially forming images on sheets;
A sheet stacking device that stacks image-formed sheets disposed on a paper discharge port of the image forming device on a tray unit;
An image forming system, wherein the sheet stacking apparatus has the configuration according to any one of claims 1 to 6.

Images