JP2011230930A - Device and method for post-processing of paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper post-processing device capable of improving the alignment of paper by reducing the disturbance of the paper discharged to a paper discharge tray.SOLUTION: The device includes a conveying part which accepts the paper supplied from an image forming apparatus thereto and conveys the paper to a post-processing part, a paper discharge part for guiding the paper passed through the post-processing part to a discharge port, the paper discharge tray on which the paper discharged from the discharge port is mounted and which can be moved so that the uppermost surface of the loaded paper can be set at a first height position lower than the discharge port and a second height position near the discharge port side, and a control unit for variably controlling a paper accepting position so that the uppermost surface of the loaded paper is set at the first height position in a first mode for processing the paper larger in paper size than a predetermined one and at the second height position in a second mode for processing the paper smaller in paper size than the predetermined one.

Description

  The present invention relates to a paper post-processing apparatus and a paper post-processing method for performing post-processing of paper discharged from an image forming apparatus such as a copying machine, a printer, or a multifunction peripheral.

  In recent years, in image forming apparatuses, a sheet post-processing device (finisher) is provided adjacent to a paper discharge unit of the image forming apparatus main body in order to sort sheets after image formation or perform post-processing such as stapling. Provided.

  For example, in a sheet post-processing apparatus that performs stapling processing, a plurality of sheets (sheet bundles) are aligned by an aligning unit to be stapled, discharged to a discharge tray, and sequentially accommodated and stacked on the discharge tray. ing. Further, when sorting is performed with a plurality of copies, when discharging the paper to the paper discharge tray, the paper is discharged while being shifted to the user side (front side) or the rear side.

  In such a paper post-processing apparatus, the post-processing of the succeeding paper is performed after completion of the post-processing of the preceding paper. By the way, a sheet for which a job such as a stapling process has been completed is discharged to a discharge tray. However, when a stapled sheet is discharged, the lower sheet may be curled by the weight of the upper sheet. Even when the paper size is small, curling may occur when the paper is discharged from the post-processing apparatus. For this reason, when the sheets are stacked on the sheet discharge tray, there are problems that the sheets are bent or the consistency is deteriorated depending on the type of post-processing job and the sheet size.

  Patent Document 1 describes an example in which paper ejection is devised to prevent the paper from being disturbed in order to stack the ejected paper on the paper ejection table in an orderly manner.

JP 2004-155551 A

  In the conventional paper post-processing apparatus, there is a problem that the paper is bent or the consistency is deteriorated when the post-processed paper is discharged to the paper discharge tray. In addition, the paper discharge device described in Patent Document 1 does not deal with the deterioration of consistency due to the post-processing job of paper and the paper size being different.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a paper post-processing apparatus and a paper post-processing method that improve the consistency by reducing the disturbance of paper discharged to a paper discharge tray.

  The present invention according to claim 1 is a post-processing device that performs post-processing as necessary on paper supplied from the image forming apparatus and discharges the paper, and receives the paper supplied from the image forming apparatus and performs post-processing. A conveyance unit that conveys the sheet to the discharge unit, a sheet discharge unit that guides the sheet that has passed through the post-processing unit, to the discharge port, and a stack of sheets discharged from the discharge port. A first height position that is lower than the first height position, a second discharge position that is closer to the discharge port side than the first height position, and the image forming apparatus. In the first mode in which the height position of the paper discharge tray is controlled according to the supplied paper size and the paper size is larger than a predetermined size, the top surface of the stacked paper is the first surface. 1 height position, the paper size is predetermined And a control unit that variably controls the receiving position of the sheet discharged from the discharge port so as to be at the second height position. Features.

  According to a sixth aspect of the present invention, there is provided a post-processing method for performing post-processing on the paper supplied from the image forming apparatus and discharging the paper if necessary, and accepting the paper supplied from the image forming apparatus, The paper that has been transported to the post-processing unit, guided through the post-processing unit, is guided to the discharge port by the paper discharge unit, the paper discharged from the discharge port is stacked on the discharge tray, and the top surface of the stacked paper is the discharge top. The image forming apparatus is configured to allow the sheet discharge tray to move so that the first height position is lower than the outlet and the second height position is closer to the discharge port than the first height position. In the first mode in which the height position of the paper discharge tray is controlled in accordance with the paper size supplied from the paper and the paper size is larger than a predetermined size, the top surface of the stacked paper is the top surface. At the first height position, the paper size There in a second mode for processing smaller sheets than a predetermined size, such that the second height position, characterized by variably controlling the receiving position of the sheets discharged from the discharge port.

  According to the present invention, when paper is discharged to the paper discharge tray, the paper discharge position is controlled depending on the type of post-processing job and the paper size, so that the paper is bent or uneven on the paper discharge tray. Therefore, it is possible to provide a sheet post-processing apparatus with good consistency.

1 is a perspective view showing a sheet post-processing apparatus according to an embodiment of the present invention. FIG. 3 is a top view illustrating the sheet post-processing apparatus according to the embodiment. The schematic block diagram which shows the paper post-processing apparatus which concerns on the same embodiment. FIG. 3 is a perspective view showing a stapler of the sheet post-processing apparatus according to the embodiment. The perspective view which shows the vertical alignment roller of the paper post-processing apparatus which concerns on the same embodiment. Explanatory drawing which shows the paddle of the paper post-processing apparatus which concerns on the embodiment. FIG. 3 is a schematic perspective view illustrating a standby tray and a processing tray of the sheet post-processing apparatus according to the embodiment. FIG. 3 is a top view showing a standby tray and a processing tray of the sheet post-processing apparatus according to the embodiment. FIG. 3 is a schematic perspective view illustrating a lateral alignment plate and a conveyance belt of the sheet post-processing apparatus according to the embodiment. FIG. 3 is a block diagram showing a control system of a paper discharge unit according to the embodiment. Explanatory drawing explaining the bending of the paper at the time of paper discharge. Explanatory drawing explaining the discharge operation | movement in the paper discharge part which concerns on the same embodiment. Explanatory drawing explaining another discharge operation in the paper discharge part which concerns on the same embodiment.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same portions are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a perspective view showing a main part of a paper post-processing apparatus according to an embodiment of the present invention, FIG. 2 is a top view of the main part of the paper post-processing apparatus according to an embodiment of the present invention, and FIG. It is a figure explaining the schematic structure of the paper post-processing apparatus which concerns on one Embodiment. 4 to 9 are diagrams illustrating the configuration of each unit of the sheet post-processing apparatus.

  The specific configuration and operation of each part in FIGS. 1 and 2 will be clarified sequentially in the description of the drawings from FIG. 4 onward. First, the paper processing in the paper post-processing apparatus of the present invention will be described with reference mainly to FIG. It explains using.

  The paper P on which an image is formed by the image forming apparatus 5 such as a copying machine is discharged from a pair of paper discharge rollers 6 and conveyed to the paper post-processing device 7. As shown in FIG. 3, the sheet post-processing device 7 includes a standby tray 10, a processing tray 12, a stapler 14, discharge trays 16 and 18, a gate G, and the like.

  The paper P discharged from the pair of paper discharge rollers 6 of the image forming apparatus 5 is received by a pair of entrance rollers 22 provided near the carry-in entrance of the paper post-processing device 7. The entrance roller 22 includes an upper roller 22a and a lower roller 22b, and is driven by an entrance roller motor 26 (FIG. 1).

  A gate G is provided on the downstream side of the entrance roller 22 to branch the paper P received by the entrance roller 22 into two paths (flows). The gate G has a wedge-shaped cross section, and the wedge-shaped pointed portion faces the vicinity of the rolling surface of the entrance roller 22. The gate G is pivotally supported by the side wall portion in the sheet post-processing apparatus 7 so that the first portion where the wedge-shaped pointed portion points to the upper inlet roller 22a and the lower inlet roller 22b are provided. Take the second position to point.

  The first position is for selecting a path when post-processing is required for the paper P, and the second position is for selecting a path when post-processing is not required for the paper P. Is.

  When the gate G is in the first position, the paper P is sent to the standby tray 10 via the first paper feed roller 24. A paper path ceiling 36 (FIG. 1) that guides the paper P to the first paper feed roller 24 is provided between the entrance roller 22 and the standby tray 10. The first paper feed roller 24 includes an upper paper feed roller and a lower paper feed roller. The standby tray 10 temporarily receives and stacks a plurality of sheets of paper P until the processing in the processing tray 12 is completed.

  Below the standby tray 10 is disposed a processing tray 12 on which the sheets P dropped from the standby tray 10 are stacked. The processing tray 12 aligns and supports the stacked paper P while the paper P is stapled by the stapler 14 which is a processing mechanism that performs post-processing.

  When a predetermined number of sheets are accumulated in the standby tray 10, the tray members 10a and 10b are opened in the directions of the arrows n and m by the standby tray motor 34 (FIG. 1), as shown in FIG. As a result, it drops onto the processing tray 12 and is supplied to the stapler 14.

  As shown in FIG. 4, the stapler 14 is positioned by sliding in the u direction by the staple driving unit 49 and performs a stapling process. Although only one stapler 14 is formed, FIG. 4 shows a state before and after sliding. The processing tray 12 aligns the plurality of sheets P dropped and supplied from the standby tray 10 in the vertical direction, which is the conveying direction, so that a pair of upper and lower upper vertical alignment rollers 38a and lower vertical alignment rollers shown in FIGS. 38b.

  The vertical and vertical alignment rollers 38a and 38b also serve as a bundle conveying roller that sandwiches the sheet bundle T after completion of the stapling process and picks it up from the stapler 14. The upper vertical alignment roller 38a is driven by a vertical alignment upper roller motor 40, and the lower vertical alignment roller 38b is driven by a vertical alignment lower roller motor 42. A rotatable paddle for aligning the uppermost sheet P placed on the processing tray 12 in the vertical direction is located at the position where the trailing edge of the sheet P drops when the sheet P is dropped and supplied to the processing tray 12. 44 is arranged.

  As shown in FIG. 6, the paddle 44 aligns the receiving portion 44 a of the paper P that is dropped and supplied onto the processing tray 12, the punching portion 44 b that scrapes off the paper P on the processing tray 12, and the paper P on the processing tray 12. It has a feed portion 44 c and is driven by a paddle motor 46. The paddle 44 is made of a rubber material and has elasticity.

  A stopper 45 is provided at the end of the processing tray 12 on the side of the stapler 14 to abut the rear end of the paper P and regulate the rear end position. Near the center of the processing tray 12, there is a conveying belt 50 that carries the stapled and the sheet bundle T taken out from the stapler 14 by the vertical and vertical alignment rollers 38a and 38b to the first or second discharge trays 16 and 18. Provided. A feed claw 50 a that hooks the rear end of the sheet bundle T is attached to the transport belt 50.

  The standby tray 10 can drop-feed the paper P to the processing tray 12, and can also be used to transport the paper P in the direction of the first or second paper discharge tray 16, 18. The conveyance of the paper P in the directions 16 and 18 is performed by bringing the rotary roller 28 for aligning the paper P into contact with the paper P on the standby tray 10. The rotary roller 28 is controlled to move up and down by a standby tray roller drive source 30 and is driven to rotate by a motor 32 (FIG. 2).

  As shown in FIG. 3, the standby tray 10 is disposed at an inclination angle θ1 in order to support the paper P in a state where the leading edge of the paper P is higher than the rear end. The paper discharge trays 16 and 18 are moved up and down by the paper discharge tray driving unit 52 to select one of them. The paper discharge trays 16 and 18 move up and down when the paper P is stacked, and receive the paper P to be discharged. The paper discharge trays 16 and 18 are arranged so as to have an inclination angle θ2.

  As shown in FIGS. 7 and 8, the standby tray 10 includes a pair of tray members 10 a and 10 b formed so as to protrude from the wall surface, and receives a sheet while sliding to the width of the sheet P, and both sides of the sheet P. Support. The tray members 10a and 10b are provided with standby stoppers 10c and 10d for regulating the rear end of the paper P.

  The standby tray 10 is slid by a standby tray motor 34 (FIG. 2). During the period from the standby tray 10 to the processing tray 12, when the paper P on the standby tray 10 is dropped and supplied to the processing tray 12, the paper P is prevented from being disturbed in the lateral direction perpendicular to the transport direction. Therefore, lateral alignment plates 47a and 47b are provided as shown in FIG. The lateral alignment plates 47a and 47b can be slid in the v direction so as to match the width of the paper P by the lateral alignment motor 48, and the alignment position can be changed.

  The motors 26, 32, 34, 40, 42, 46, 48 and the drive units 49, 52 that drive the various mechanisms described above are driven and controlled by a control circuit.

  Next, the operation of the sheet post-processing device 7 will be described along the sheet flow. Note that the post-processed paper is discharged to either the paper discharge tray 16 or 18, but in the following description, a case where the paper is discharged to the paper discharge tray 16 will be described as a representative example.

  First, when paper post-processing is not performed, when an image is formed by the image forming apparatus 5 and the paper P is supplied from the paper discharge roller 6, the paper discharge tray 16 is positioned at a position indicated by a dotted line or a solid line in FIG. The sheet P discharged from the standby tray 10 can be received and stacked. In this case, the gate G is in the first position, and the paper P conveyed from the entrance roller 22 through the paper path ceiling 36 is fed onto the standby tray 10 by the paper feed roller 24. Next, the sheet P is lowered onto the standby tray 10 and conveyed by the rotating roller 28 rotating in the direction of arrow f, and is discharged onto the discharge tray 16.

  Next, when post-processing (stapling processing) is performed and there is no preceding paper P on the processing tray 12, the gate G is also in the first position, and the standby tray 10 has the tray members 10a and 10b. The paper P slides and moves in the direction of arrow m or arrow n in FIG. The horizontal alignment plates 47a and 47b are arranged so that the width between the horizontal alignment plates 47a and 47b is substantially the same as the width of the paper P in order to align the horizontal direction of the paper P dropped from the paper feed roller 24. Thereby, the paper P fed by the paper feed roller 24 is dropped and supplied directly onto the processing tray 12 without being interrupted by the standby tray 10.

  At the time of dropping, the upper vertical alignment roller 38a is retracted upward, and the receiving portion 44a of the paddle 44 receives the rear end of the paper P. Both sides of the paper P fall while contacting the horizontal alignment plates 47a and 47b, and are aligned in the horizontal direction. Next, the paddle 44 rotates in the direction of the arrow o in FIG. 6 to drop the trailing edge of the paper P from the receiving portion 44a, and then knocks it onto the processing tray 12 by the knocking portion 44b. Further, the paddle 44 feeds the paper P in the direction of the arrow q by the feeding portion 44c, and the rear end of the paper P is brought into contact with the stopper 45 to complete the vertical alignment of the paper P.

  In this way, the image-formed sheets P are stacked directly on the processing tray 12 from the sheet feed roller 24 while sequentially aligning in the horizontal and vertical directions. When the number of sheets P reaches a predetermined number, the stapler 14 staples the sheets P on the processing tray 12 at a desired position to form a bundle of sheets T. After that, as shown in FIG. 6, the sheet bundle T is sandwiched between the upper vertical alignment roller 38a rotating in the direction of the arrow r and the lower vertical alignment roller 38b rotating in the direction of the arrow s, and is conveyed in the direction of the paper discharge tray 16.

  When the rear end of the sheet bundle T passes through the vertical and vertical alignment rollers 38a and 38b, the sheet bundle T is hooked on the feeding claw 50a of the conveying belt 50 rotated in the direction of arrow t in FIG. Thereafter, the paper is bundled on the paper discharge tray 16 by the discharge roller 38c.

  The paper discharge tray 16 is arranged so that the inclination angle is θ2, and the front end of the paper is higher than the rear end. The paper P discharged to the paper discharge tray 16 is sequentially discharged without being out of order. It is placed on the paper tray 16.

  Next, when the stapling process is performed and the sheet P that is being subjected to the stapling process remains on the processing tray 12, the standby tray 10 has the tray members 10a and 10b as shown by the arrows in FIG. The paper P can be supported by sliding in the direction opposite to the m direction and the n direction. The rotating roller 28 is retracted above the standby tray 10 so as not to interfere with the paper P. The paper P discharged from the image forming apparatus 5 and supplied by the paper supply roller 24 is temporarily placed on the standby tray 10 in order to wait for the processing tray 12 to become empty.

  The second and subsequent sheets P placed on the standby tray 10 descend on the standby tray 10 and are sent in the directions of the standby stoppers 10c and 10d by the rotating roller 28 rotated in the direction opposite to the arrow f direction in FIG. Then, the rear end of the paper P is brought into contact with the standby stoppers 10c and 10d to be vertically aligned. Further, since the standby tray 10 is arranged so that the inclination angle is θ1, and the leading edge of the sheet is higher than the trailing edge, the sheet P is vertically contacted by the dead weight with the waiting stoppers 10c and 10d by its own weight. Align.

  When the preceding paper P on the processing tray 12 is discharged to the discharge tray 16 side and the processing tray 12 becomes empty, the standby tray 10 moves the tray members 10a and 10b in the direction of arrow m or arrow n in FIG. Move the slide.

  As a result, for example, two sheets of paper P waiting on the standby tray 10 are dropped and supplied onto the processing tray 12 from between the tray members 10a and 10b. Thereafter, the sheet P is regulated by the horizontal alignment plates 47a and 47b on both sides and aligned in the horizontal direction, and is sent in the direction of the arrow q by the lower vertical alignment roller 38b as described in FIG. The end of the sheet P is brought into contact with the stopper 45 and the sheet P is aligned in the vertical direction. Similarly, the third and subsequent sheets of paper P are dropped and supplied directly onto the processing tray 12 from between the tray members 10a and 10b, and sequentially aligned on the paper P previously stacked on the processing tray 12 by the paddle 44. The

  When the number of sheets P stacked on the processing tray 12 reaches a predetermined number, the stapler 14 performs a stapling process to form a sheet bundle T, and then the sheet bundle T is moved in the direction of the sheet discharge tray 16 by the vertical and vertical alignment rollers 38a and 38b. The bundle is conveyed and further, the rear end is hooked on the feed claw 50a of the conveyance belt 50 and is bundled and conveyed toward the sheet discharge tray 16, and is then bundled onto the sheet discharge tray 16 by the discharge roller 38c.

  When sorting sheets, the sheet P is shifted to the user side (front side) or the rear side by the lateral alignment plates 47a and 47b, and when there are a plurality of copies, the discharge position is shifted back and forth for each number of copies. Are discharged.

  The above is a description of the overall operation of the paper post-processing apparatus 7. Next, the configuration of the paper discharge unit to the paper discharge tray 16, which is a characteristic part of the present invention, will be described.

  The paper discharge unit changes the height position of the paper discharge tray 16 in accordance with the type of post-processing job or the paper size. As shown in FIG. 3, the paper discharge unit is located near the discharge port 70 of the paper post-processing device 7. A sensor 71 is provided to detect the uppermost surface of the paper discharged onto the paper discharge tray 16 and to regulate the height position of the paper discharge tray 16 in response to the detection result of the sensor 71. Further, an input state from the operation unit 72 provided in the image forming apparatus 5 is detected in order to determine the type of post-processing job or the paper size.

  FIG. 10 is a block diagram showing a control system for controlling the paper discharge unit. In FIG. 10, reference numeral 81 denotes a control circuit that controls the image forming apparatus 5. The control circuit 81 includes, for example, a microprocessor including a CPU, and controls each unit for image formation in response to an operation of the operation unit 72. . The operation unit 72 is provided with a key 73 for selecting a post-processing job (for example, stapling, sorting, etc.) and a key 74 for selecting a paper size. When the user performs printing or the like, The paper size can be selected.

  Reference numeral 82 denotes a control circuit for controlling the sheet post-processing device 7, which is composed of, for example, a microprocessor including a CPU, and transmits information to and from the control circuit 81 on the image forming apparatus 5 side for image formation. Each unit is controlled for paper post-processing so that the operation and the operation of the paper post-processing device 7 are linked. Further, the control circuit 82 controls a drive motor 83 provided in the paper discharge tray driving unit 52 and a drive motor 84 that rotates the transport belt 50. As described above, the feed claw 50 a that hooks the rear end of the sheet bundle T is attached to the conveyance belt 50, and the feed claw 50 a sends the sheet bundle T toward the discharge port 70 by the rotation of the conveyance belt 50. . Further, the detection result from the sensor 71 is input to the control circuit 82.

  In general, the paper discharge tray 16 waits at a height position (H1) below the discharge port 70 so as to catch the discharged paper falling. When the sheet bundle T is discharged, the sheet on the lower side of the sheet bundle T is easily curled by the weight of the upper sheet as shown in FIG. For this reason, when the paper is discharged to the paper discharge tray 16, the curled paper may be bent.

  Further, even when the paper size is small, as shown in FIG. 11B, it is easy to curl when the paper is discharged. When the paper size is large (for example, A3 size), the leading edge of the paper hits the paper discharge tray 16 and is not easily curled. However, when the paper size is small, such as A4 size, LT, B5, etc. In some cases, the front and back were reversed.

  The paper discharge unit according to the present invention prevents the paper from being bent (curled) at the time of paper discharge and improves the consistency. FIGS. 12 and 13 are operation explanatory views for explaining the operation of the paper discharge unit under the control of the control circuits 81 and 82. FIG.

  FIG. 12 illustrates the movement of the paper discharge tray 16 when the stapling process is selected as the paper post-processing job. When the user selects the stapling process by operating the key 73, FIG. As described above, the paper discharge tray 16 rises from the normal standby position (first height position: H1) and moves to the second height position. The second height position (H2) is lower than the position of the sensor 71, and the sensor 71 is set to a position where the uppermost surface of the sheet can be detected.

  In FIG. 12A, the stapled sheet bundle T is hooked on the feeding claw 50a provided on the conveyor belt 50, and the feeding claw 50a ejects the sheet bundle T by the rotation of the conveyor belt 50 during ejection. It sends out toward the exit 70. At this time, since the discharge tray 16 is at the second height position H2, even if the leading end of the discharged sheet bundle T tries to curl downward, it is regulated by the discharge tray 16 and discharged without curling. .

  When the feed claw 50a moves and approaches the discharge port 70, as shown in FIG. 12B, the paper discharge tray 16 descends once, and collides with the paper discharge tray 16 when the feed claw 50a passes. Go down to the position where you want to prevent it.

  The time for the feeding claw 50a to approach the discharge port 70 can be calculated by the control circuit 82, and can be obtained based on the start time of the paper discharge operation and the moving speed of the transport belt 50. Therefore, the control is performed to lower the position of the paper discharge tray 16 when it approaches the discharge port 70 after the feeding claw 50a starts to carry out. Alternatively, a sensor that detects that the feed claw 50a has approached the discharge port 70 may be provided, and the position of the discharge tray 16 may be lowered according to the detection result.

  When the feed claw 50a rotates and moves away from the paper discharge tray 16, as shown in FIG. 12C, the paper discharge tray 16 rises again and receives and stacks the discharged paper bundle T. At this time, the upper surface of the sheet bundle T is detected by the sensor 71, and the discharge tray 16 is stopped at a position where the uppermost surface of the sheet bundle T is at the second height position H2. Accordingly, the discharged paper is stacked on the paper discharge tray 16 without curling.

  On the other hand, when sort is selected as the post-processing, the sheets are discharged to the discharge tray 16 in order without being bound, so that the lower sheet is curled by the weight of the upper sheet as in the stapling process. Therefore, the sheet is received at the normal standby position (H1). Similarly, during standard processing without post-processing, since the sheets are discharged one by one to the discharge tray 16 one by one, the sheets are received at the normal standby position (H1).

  FIG. 13 is an operation explanatory diagram in the case of controlling the height position of the paper discharge tray 16 in accordance with the size of the paper supplied from the image forming apparatus 5, and has a small size (for example, A4, LT, B5, etc.). The movement of the paper discharge tray 16 when a sheet is selected will be described.

  When the user operates the key 74 to select A4, for example, as shown in FIG. 13A, the paper discharge tray 16 rises from the normal standby position (first height position: H1), and the second Move to height position (H2).

  In FIG. 13A, the rear end of the sheet bundle P is hooked on a feed claw 50a provided on the transport belt 50, and the feed claw 50a sends the paper P toward the discharge port 70 by the rotation of the transport belt 50 during discharge. To do. At this time, since the paper discharge tray 16 is at the second height position H2, even if the leading end of the discharged paper P tries to curl downward, the paper discharge tray 16 hits the paper discharge tray 16 and is discharged without curling.

  Further, when the feed claw 50a moves and approaches the discharge port 70, as shown in FIG. 13B, the paper discharge tray 16 descends one end and collides with the paper discharge tray 16 when the feed claw 50a passes. Go down to the position where you want to prevent it.

  When the feed claw 50a rotates and moves away from the paper discharge tray 16, as shown in FIG. 13C, the paper discharge tray 16 rises again and receives and stacks the discharged paper P. At this time, the upper surface of the paper P is detected by the sensor 71, the paper discharge tray 16 is stopped at a position where the uppermost surface of the paper P is at the second height position H2, and the next paper sequentially discharged is awaited. Accordingly, the discharged paper is stacked on the paper discharge tray 16 without curling.

  On the other hand, when a large size paper such as A3 is selected, the paper does not curl because the paper hits the paper discharge tray 16 before the leading edge of the paper curls (see FIG. 11b). The paper is received in H1).

  Even when the sheet is received at the normal standby position (H1), the upper surface of the sheet discharged onto the sheet discharge tray 16 is detected by the sensor 71 so that the uppermost surface of the sheet is at the first height position H1. In addition, the position of the paper discharge tray 16 is controlled.

  In the above description, the example of determining the type of post-processing job and the paper size based on the operation content of the operation unit 72 has been described. However, the image forming apparatus 5 and the personal computer (PC) are connected to the network. When a document created on a PC is printed on the image forming apparatus 5, the designation status from the PC is grasped by the image forming apparatus 5, and the type of paper post-processing and the like are determined based on the grasped result. The paper size can also be determined.

  As described above, according to the present invention, when the paper is discharged to the paper discharge tray, the position of the paper discharge tray is controlled according to the type of post-processing and the paper size, thereby suppressing the bending of the paper and discharging the paper. It is possible to provide a paper post-processing apparatus with good consistency by suppressing bending on the tray and paper variation.

  The present invention is not limited to the above description, and various modifications can be made without departing from the scope of the claims.

DESCRIPTION OF SYMBOLS 5 ... Image forming apparatus 7 ... Paper post-processing apparatus 10 ... Standby tray 12 ... Processing tray 14 ... Stapler 16, 18 ... Paper discharge tray 22 ... Entrance roller 24 ... Paper feed roller 38a, b, c ... Rotating roller 50 ... Conveying belt 50a ... Feeding claw 70 ... Discharge port 71 ... Sensor 72 ... Operation unit 73, 74 ... Selection key 81, 82 ... Control circuit 83, 84 ... Drive motor P ... Paper T ... Paper bundle

Claims (6)

A post-processing device that performs post-processing as necessary on paper supplied from the image forming apparatus and discharges the paper.
A transport unit that receives the paper supplied from the image forming apparatus and transports the paper to the post-processing unit;
A paper discharge section for guiding the paper that has passed through the post-processing section to the discharge port;
The sheets discharged from the discharge port are stacked, and the top surface of the stacked sheets is a first height position lower than the discharge port, and a second position closer to the discharge port side than the first height position. A paper discharge tray that can be moved to a height position of
In the first mode in which the height position of the paper discharge tray is controlled in accordance with the paper size supplied from the image forming apparatus and the paper size is larger than a predetermined size, In the second mode in which the top surface is at the first height position and the paper size is smaller than a predetermined size, the paper is discharged from the discharge port so that the second height position is obtained. And a control unit that variably controls the receiving position of the received paper.   The first mode is a mode for processing a paper having a paper size larger than A4, and the second mode is a mode for processing a paper having a paper size of A4 or smaller. The sheet post-processing apparatus according to claim 1. A sensor that is mounted near the discharge port and detects the uppermost surface of the paper stacked on the discharge tray;
In the first mode, the control unit waits for the paper discharge tray at a position where the uppermost surface of the paper stacked on the paper discharge tray is at the first height position based on the detection result of the sensor. In the second mode, the discharge tray is made to stand by at a position where the uppermost surface of the paper stacked on the discharge tray is at the second height position based on the detection result of the sensor. The sheet post-processing apparatus according to claim 1, wherein the sheet post-processing apparatus is controlled. The paper discharge unit includes a conveyance belt and a claw portion attached to the conveyance belt and sending the paper to a discharge port.
In the second mode, the control unit temporarily moves the paper discharge tray to a position lower than the second height position when the claw portion moves to the vicinity of the discharge port. 2. The sheet post-processing apparatus according to claim 1, wherein the sheet is raised again after the sheet is discharged by the section.   2. The post-sheet processing according to claim 1, wherein an operation unit capable of selecting a paper size by a user operation is provided in the image forming unit, and the control unit determines a paper size to be processed based on the selection result. Processing equipment. A post-processing method for performing post-processing on a sheet supplied from an image forming apparatus as necessary, and discharging the paper.
Accepts the paper supplied from the image forming apparatus, conveys it to the post-processing unit,
The paper that has passed through the post-processing unit is guided to the discharge port by the paper discharge unit,
The paper discharged from the discharge port is stacked on a discharge tray, and the top surface of the stacked paper is at a first height position lower than the discharge port, and on the discharge port side from the first height position. The paper discharge tray is movable to a second height position close to
In the first mode in which the height position of the paper discharge tray is controlled in accordance with the paper size supplied from the image forming apparatus and the paper size is larger than a predetermined size, In the second mode in which the top surface is at the first height position and the paper size is smaller than a predetermined size, the paper is discharged from the discharge port so that the second height position is obtained. Post-processing method for variably controlling the receiving position of the received paper.

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