Sheet processing device and image forming system

Abstract

The present invention provides a sheet processing apparatus capable of reducing localized wear of a sheet holding member, and an image forming system equipped therewith. [Solution] The stacking section 15 and the pressing member 50 are controlled so that the area in which the contact portion 50b contacts the upper surface of the sheet on the stacking section 15 when the contact portion 50b presses down on the sheet on the stacking section 15 is changed according to the number of rotations of the pressing member 50.

Description

Technical Field

[0001] The present invention relates to a sheet processing apparatus that performs a predetermined process on a sheet and discharges it, and more particularly to a sheet processing apparatus capable of accurately operating a sheet pressing unit that presses a sheet discharged to a stacking unit, and an image forming system including the same.

Background Art

[0002] In recent years, not only are sheets formed by an image forming apparatus simply discharged as they are, but also a sheet processing apparatus that performs staple processing, folding processing, etc. on the formed sheets is assembled integrally with the image forming apparatus and used.

[0003] In such a sheet processing apparatus, staple-processed sheet bundles are stacked and discharged onto a stacking tray, and a pressing member is provided to press the upper surface of the already stacked sheets so that the discharged sheet bundle does not push out the already discharged sheet bundle on the stacking tray (Patent Document 1). For example, as shown in FIG. 16, a pressing member 500 made of an elastically deformable member such as a rubber plate is rotatably provided, and each time a sheet bundle 502 is discharged onto the stacking tray 501, the pressing member 500 is rotated to press the upper surface of the discharged sheet, thereby preventing the already stacked sheets from being pushed out.

[0004] Further, the stacking tray 501 is configured to be able to move up and down along the rising surface 503. When a certain number of sheets are discharged onto the stacking tray 501 in the sheet receiving position, the stacking tray 501 is lowered so that the uppermost sheet stacked on the stacking tray 501 becomes the sheet receiving position. Then, when it is determined that a plurality of sheets stacked on the stacking tray 501 have been removed, the stacking tray is raised to the sheet receiving position. Thereby, the uppermost sheet discharged onto the stacking tray can be accurately pressed by the pressing member 500.

[0005] A sheet surface detection sensor 504 is provided to position the top surface of the loading tray 501 or the top surface of the uppermost sheet loaded on the loading tray at the sheet receiving position. This sheet surface detection sensor 504 turns on when there is a loading tray or sheet at the sensor's detection position, and turns off when there is no loading tray or sheet at the sensor's detection position. The loading tray is raised and lowered according to the output of this sheet surface detection sensor 504. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-20999 [Overview of the project] [Problems that the invention aims to solve]

[0007] In the configuration described above, where the loading tray is raised and lowered, as shown in Figure 17(a), when the sheet surface detection sensor 504 is off after a sheet has been discharged, it is determined that the sheet on the loading tray 501 has been removed, and the loading tray 501 is raised until the sheet surface detection sensor 504 turns on. At this time, if sheet discharge is continuing, the retaining member 500 is positioned at the retaining position angle (tip facing downward) in order to discharge the next sheet.

[0008] The aforementioned retaining member 500 is made of a rubber plate or the like with a thickness of several millimeters, and a gap 505 is formed between the loading tray 501 and the upright surface 503 to allow the loading tray 501 to move up and down smoothly. Therefore, if the loading tray is raised all at once to the position where the sheet surface detection sensor 504 turns on, as shown in Figure 17(b), the elastically deformable contact portion of the retaining member 500 may get caught in the gap between the loading tray 501 and the upright surface 503. If the retaining member 500 gets caught in the gap 505, the retaining member 500 will not be able to rotate, which may cause a malfunction in the discharge operation.

[0009] Such bending of the pressing member 500 is more likely to occur due to localized wear of the contact portion of the pressing member. Wear of the contact portion occurs when the contact portion rotates while pressing down on the sheet. Therefore, if the sheet pressing and rotation actions are repeated in a configuration where the sheet is pressed down on the same part of the contact portion, localized wear will occur on the contact portion of the pressing member, and as described above, the worn portion of the contact portion may bend and get caught in the gap between the loading tray and the upright surface.

[0010] The present invention has been made in view of the above problems, and its purpose is to provide a sheet processing apparatus and an image forming system equipped therewith that can reduce local wear of the contact portion of the sheet pressing member so that the contact portion does not bend and get caught in the gap between the loading tray and the upright surface. [Means for solving the problem]

[0011] A typical configuration according to the present invention for achieving the above objective is a sheet processing unit for performing a predetermined process on a sheet; a discharge unit for discharging the sheet; a loading unit for loading the sheets discharged by the discharge unit, the loading unit being able to move up and down along an upright surface; a sheet surface detection sensor for detecting the height of the upper surface of the loading unit or the top sheet of the sheet bundle loaded in the loading unit; a rotatable and elastically deformable pressing member for pressing down the upper surface of the sheet discharged into the loading unit; and a control unit for controlling the movement of the loading unit and the pressing member, wherein the control unit controls the pressing member when a subsequent sheet is continuously discharged to the loading unit following a previous sheet. The loading section rotates to a pressing position for pressing down on the upper surface of the previous sheet, moves the loading section so that the upper surface of the previous sheet is at a height that can receive the subsequent sheet, and repeatedly discharges the subsequent sheet while the pressing member is in the pressing position. If it is determined that a sheet loaded on the loading section has been removed while sheets are being discharged continuously, the loading section is raised until the loading section or the sheet on the loading section is detected by the sheet surface detection sensor, and the loading section and the pressing member are controlled to change the area in which the contact portion contacts the upper surface of the sheet on the loading section when the contact portion presses down on the sheet on the loading section, according to the number of rotations of the pressing member. [Effects of the Invention]

[0012] In this invention, the wear points of the sheet-holding member are dispersed, reducing localized wear. This makes it possible to suppress malfunctions caused by bending of the sheet-holding member. [Brief explanation of the drawing]

[0013] [Figure 1] Schematic diagram of the overall configuration of an image forming system equipped with a sheet processing device. [Figure 2] Perspective view of the sheet processing device [Figure 3] Diagram illustrating the configuration of the sheet processing device. [Figure 4] Diagram illustrating sheet alignment and binding operations. [Figure 5] Explanatory drawing of the lifting mechanism of the loading tray [Figure 6] Explanatory drawing of the drive mechanism of the sheet pressing paddle [Figure 7] Control configuration block diagram of the image forming system [Figure 8] Diagram showing the bending direction of the paddle part due to wear of the tip corner part of the paddle part [Figure 9] Flowchart showing the position control of the loading tray corresponding to the number of discharges in the sheet discharge job [Figure 10] Diagram showing the contact area between the paddle part and the sheet when the loading tray is in the first position [Figure 11] Diagram showing the contact area between the paddle part and the sheet when the loading tray is in the second position [Figure 12] Diagram showing the contact area between the paddle part and the sheet when the loading tray is in the third position [Figure 13] Diagram showing the operation of the loading tray when the sheet is removed from the loading tray [Figure 14] Flowchart showing the rotation angle control of the sheet pressing paddle corresponding to the number of discharges in the sheet discharge job [Figure 15] Diagram showing the contact area between the paddle part and the sheet when the rotation angle of the sheet pressing paddle changes [Figure 16] Explanatory drawing of the prior art [Figure 17] Explanatory drawing of the prior art

Mode for Carrying Out the Invention

[0014] 〔First Embodiment〕 Next, a sheet processing apparatus according to a preferred embodiment of the present invention and an image forming system including the same will be described with reference to the drawings. FIG. 1 schematically shows the overall configuration of an image forming system including the sheet processing apparatus according to the embodiment of the present invention. As shown in the figure, the image forming system C includes an image forming apparatus A and a sheet processing apparatus B provided therewith.

[0015] <Image forming apparatus> Image forming apparatus A consists of an image forming unit A1, a scanner unit A2, and a feeder unit A3. The image forming unit A1 has a feeding section 2, an image forming section 3, and an discharge section 4 inside the apparatus housing 1.

[0016] The feeding unit 2 consists of multiple cassette mechanisms 2a, 2b, and 2c, each storing image forming sheets of different sizes, and feeds sheets of a specified size from the main control unit to the feeding path 2f. Each cassette mechanism 2a, 2b, and 2c is detachably installed from the feeding unit 2 and contains a separation mechanism for separating the sheets one by one and a feeding mechanism for feeding the sheets. The feeding path 2f is provided with transport rollers for feeding the sheets supplied from each cassette mechanism 2a, 2b, and 2c downstream, and pairs of registration rollers at the ends of the path for aligning the leading edges of each sheet.

[0017] In this embodiment, the image forming unit 3 is configured using an electrophotographic method and comprises a rotating photosensitive drum 3a and, arranged around it, a charging roller 3b, an exposure unit 3c, a developer unit 3d, and a cleaner (not shown). The illustrated diagram shows a color printing mechanism, in which the image forming mechanism is provided according to the respective colors: yellow Y, magenta M, cyan C, and black K.

[0018] During image formation, the circumferential surface of the rotating photosensitive drum 3a is uniformly charged by the charging roller 3b, and light corresponding to the image signal is irradiated by the exposure unit 3c to form an electrostatic latent image. This latent image is then developed by the developer unit 3d to form a toner image. The toner images of each color formed in this way are first transferred to the rotating intermediate transfer belt 3e to form a color image. In conjunction with the timing of this image formation, the sheet is sent from the supply path 2f to the secondary transfer unit, and a transfer bias is applied from the secondary transfer roller 3f to transfer the toner image formed on the intermediate transfer belt 3d onto the sheet. As the sheet with the transferred toner image passes through the fuser unit 5, it is heated and pressurized to fix the toner image, and then discharged from the discharge port 4b by the discharge roller 4a and transported to the sheet processing device B described later.

[0019] Scanner unit A2 comprises a platen 6a on which an image document is placed, a carriage 6b that reciprocates along the platen 6a, a photoelectric conversion element 6c, and a reduction optical system 6d that guides the reflected light from the document on the platen 6a by the carriage 6b to the photoelectric conversion element 6c. The photoelectric conversion element 6c converts the optical output from the reduction optical system 6d into image data using photoelectric conversion and outputs it as an electrical signal to the image forming unit 3. Scanner unit A2 is also capable of reading document sheets that are fed in from feeder unit A3.

[0020] <Sheet processing device> Next, we will explain the overall configuration of the sheet processing device B, which processes the sheets sent from the image forming apparatus A.

[0021] Figure 2 is a perspective view of the sheet processing apparatus according to this embodiment, and Figure 3 is an explanatory diagram of the configuration of the sheet processing apparatus B. The sheet processing apparatus B includes an apparatus housing 11 provided with an inlet 10 for introducing sheets from the image forming apparatus A. The apparatus housing 11 is positioned in alignment with the housing 1 of the image forming apparatus A so that the inlet 10 communicates with the outlet 4b of the image forming apparatus A.

[0022] In this embodiment, the discharge section 4 of the image forming apparatus A is formed in a space (internal space) 4c formed between the image forming unit A1 and the scanner unit A2, and the sheet processing apparatus B is located in the space 4c.

[0023] The sheet processing device B consists of a device frame 11, a sheet transport path 12 arranged on the device frame 11, a processing tray 14 located downstream of the transport path exit 13, and a loading tray 15 located further downstream. As shown in Figure 2, the front side of the device frame 11 is equipped with a staple needle cartridge mounting opening 16, a manual feed setting section 17, and manual operation buttons 18.

[0024] Furthermore, the processing tray 14 is equipped with a scraping paddle 19 made of a rubber plate that scrapes the sheets into the rear end stopper 21, and a knurled rubber belt 20 with knurling on its outer surface. In addition, a sheet rear end stopper 21 and alignment plate 22 are arranged to stack the sheets in bundles. The processing tray 14 is also equipped with a stapling unit 23 for stapling the sheet bundles and a stapleless stapling unit 24 for stapling the sheet bundles without staples.

[0025] (Sheet binding mechanism) The sheet on which the image has been formed by the image forming apparatus A is fed from the discharge port 4b of the image forming apparatus to the receiving port 10 of the sheet processing apparatus B, where predetermined sheet processing is performed in the sheet processing apparatus. In the sheet processing apparatus of this embodiment, the sheet P fed in from the receiving port 10 is transported by a transport roller 30a, which is a sheet transport member provided in the sheet transport path 12, as shown in Figure 4(a), and is transported to the processing tray 14 by a transport roller 30b, which is a sheet transport member provided near the transport path exit 13.

[0026] The sheet P, which is transported from the transport path exit 13 to the processing tray 14, is scraped off by the counterclockwise rotating scraping paddle 19 shown in Figure 4(b), and is transported by the counterclockwise rotating knurled belt 20 so that the rear end of the sheet abuts against the sheet rear end stopper 21, and the alignment plate 22 is slid in the sheet width direction to align both sides of the sheet in the width direction.

[0027] After transporting a predetermined number of sheets to the processing tray 14 as described above, the stapling unit 23, which is a processing unit, is operated to perform stapling on the sheet bundle on the processing tray 14. Once the sheets have been stapled, the upper discharge roller 31a of the separated discharge roller pair 31a, 31b moves and nips the sheets on the processing tray 14. Then, as shown in Figure 4(c), the driving force of the discharge motor is transmitted to the lower discharge roller 31b, and the sheets are discharged by the rotating discharge roller pair 31a, 31b and loaded into the loading tray 15, which serves as the sheet loading section. This loading tray 15 is equipped with a tray lifting mechanism that lowers it sequentially according to the amount of sheets loaded.

[0028] (Loading tray lifting mechanism) Figure 5 shows the lifting mechanism (lifting section) for raising and lowering the loading tray 15. As shown in Figure 5, the base 40 of the loading tray 15 is mounted so as to be slidable vertically along a rail (not shown) formed in the device housing 11. A rack section 41 is formed on the tray base 40, and this rack section 41 meshes with a pinion gear 42 provided on the device housing 11. The pinion gear 42 receives driving force from the tray lifting motor M1 via a transmission gear 43 and rotates, causing the rack section 41 to move up and down, thereby raising and lowering the loading tray 15. An encoder 44 that rotates integrally with the pinion gear 42 is attached to it, and the amount of lifting and lowering of the loading tray 15 can be controlled by detecting the amount of rotation of this encoder 44.

[0029] Furthermore, a loading tray HP sensor Sn1 is provided at a predetermined position on the device housing 11, and this sensor Sn1 detects a sensor flag 45 provided on the tray base 40, thereby enabling the loading tray 15 to be positioned in the home position.

[0030] The loading tray 15 is controlled to move up and down in accordance with the discharge of the sheets, as will be described later. The sheet holding paddle 50 is also controlled to rotate in accordance with the discharge of the sheets and the raising and lowering of the loading tray 15.

[0031] (Seat holding paddle) The sheet-holding paddle 50 acts as a sheet-holding member that prevents previously loaded sheets from being pushed out by sheets subsequently discharged onto the loading tray 15 by pressing down on the upper surface of the sheets that have been discharged onto the loading tray 15. This sheet-holding paddle 50 is rotatable coaxially with the lower discharge roller 31b and is also rotatable independently of the lower discharge roller 31b.

[0032] Figure 6(a) is a perspective view showing the drive configuration of the lower discharge roller 31b and the sheet-holding paddle 50.

[0033] The lower discharge roller 31b is driven by the discharge motor M2 via a drive transmission mechanism 32. In the illustrated example, the drive transmission mechanism 32 consists of a pulley and a belt, and transmits the rotational drive of the drive shaft of the discharge motor M2 to the rotation shaft 31b1 of the lower discharge roller 31b. On the other hand, the sheet pressing paddle 50 is driven by the sheet pressing paddle motor M3, which acts as the drive unit, via a drive transmission mechanism 51. In the illustrated example, the drive transmission mechanism 51 consists of a pulley and a belt, and transmits the rotational drive of the drive shaft of the sheet pressing paddle motor M3 to the rotation shaft 52 of the sheet pressing paddle 50.

[0034] The rotating shaft 31b1 of the lower discharge roller 31b is designed so that the rotating shaft 52 of the sheet-holding paddle 50 can pass through its interior, allowing the two sheet-holding paddles 50 located on either side of the lower discharge roller 31b's rotation axis to be mounted on a single rotating shaft 52. The rotating shaft 31b1 of the lower discharge roller 31b is rotatably supported on the rotating shaft 52 of the sheet-holding paddle 50, for example, via a bearing. This allows the lower discharge roller 31b and the sheet-holding paddle 50 to be driven independently by separate motors. In addition to the pulley and belt configuration, the drive transmission mechanisms 32 and 51 may also be configured using other drive transmission members, such as multiple gears.

[0035] As shown in Figure 6(b), the sheet-holding paddle 50 has a fixed portion 50a fixed to the rotating shaft 52 and a plate-shaped paddle portion 50b that serves as an elastic contact portion provided on the fixed portion 50a. The paddle portion 50b extends from the fixed portion 50a fixed to the rotating shaft 52 in a direction perpendicular to the rotating shaft 52. The paddle portion 50b is made of an elastic material such as rubber (for example, ethylene propylene rubber (EPDM) with a hardness of 30±5HS(A) ((old JIS K6301, spring type A))). The sheet-holding paddle 50 configured in this way rotates with the rotation of the rotating shaft 52, and when the paddle portion 50b comes into contact with the sheet on the loading tray 15, it elastically deforms to hold down the rear end of the sheet.

[0036] Furthermore, a sensor flag 53 is provided on the rotation axis 52 of the sheet-holding paddle 50 so as to rotate integrally with the rotation axis 52, and a paddle HP sensor Sn2 capable of detecting the sensor flag 53 is provided in the device housing 11. The position where the paddle HP sensor Sn2 detects the sensor flag 53 becomes the home position of the sheet-holding paddle 50.

[0037] <Department Head> Next, the control configuration of the image forming system described above will be explained with reference to the block diagram in Figure 7.

[0038] The image forming system of this embodiment includes an image forming control unit 200 of the image forming apparatus A and a sheet processing device control unit (CPU: also called MPU; that is, a chip that integrates the calculation functions of a CPU, not just the calculation part) 100 of the sheet processing device B. The image forming control unit 200 includes a sheet feeding control unit 201 and an input unit 202. The "print mode" and "sheet processing mode" are set from a control panel 203 provided on the input unit 202.

[0039] The sheet processing control unit 100 operates the sheet processing device B according to the sheet processing mode. This sheet processing control unit 100 is equipped with a ROM that stores the operation program shown in the flowchart of Figure 8, and a RAM that stores control data. The sheet processing control unit 100 also receives signals from various sensors from the various sensor input unit 101, such as the loading tray HP sensor Sn1 that detects the home position of the loading tray 15, the paddle HP sensor Sn2 that detects the home position of the sheet holding paddle 50, and the sheet surface detection sensor Sn3 that detects the top surface of the sheet loaded on the loading tray 15. The sheet surface detection sensor Sn3 detects the sheet loading surface of the loading tray 15, and the position of the top surface of the loaded sheet when a sheet is loaded on the loading tray 15, and is provided at a predetermined position in the movement area of ​​the loading tray 15. The sheet surface detection sensor Sn3 turns on when it detects a sheet loaded on the loading tray 15, and turns off when it does not detect a sheet.

[0040] Furthermore, the sheet processing apparatus control unit 100 includes a sheet transport control unit 104 that controls the discharge motor M2 which provides driving force to the discharge roller 31b, the transport motor M4 which provides driving force to the transport rollers 30a and 30b, and the like.

[0041] Furthermore, the sheet processing device control unit 100 includes a processing tray control unit 105 that controls the driving of a matching motor that moves the matching plate 22 which performs sheet stacking operations on the processing tray 14, and a motor that rotates the scraping paddle 19 and the knurling belt 20. In addition, the sheet processing device control unit 100 has a stapling control unit 106 that performs stapling operations on the sheet bundles on the processing tray 14.

[0042] Furthermore, the sheet processing control unit 100 also includes a sheet loading control unit 107 that controls the loading tray lifting motor M1 for raising and lowering the loading tray 15, the sheet holding paddle motor M3 for operating the sheet holding paddle 50, and the like.

[0043] The control unit described above controls the execution of sheet processing, such as image formation processing and sheet discharge and loading processing.

[0044] <Sheet discharge and loading processing control> In the sheet processing device B of this embodiment, when discharging sheets stapled by the staple binding unit 23 to the loading tray 15, the upper surface of the sheets is pressed down while discharging by driving and controlling the lifting and lowering movement of the loading tray 15 and the rotational movement of the sheet pressing paddle 50. At this time, to prevent concentrated wear on one part of the paddle portion 50b, the area in which the paddle portion 50b contacts the upper surface of the sheet on the loading tray 15 is not limited to a specific location. Next, the control configuration for this purpose will be described.

[0045] When a sheet is discharged onto the loading tray 15, the sheet-holding paddle 50 rotates and contacts the top surface of the sheet, elastically deforming to hold the sheet down. When the next sheet is discharged, it rotates again and holds down the top surface of the next sheet in the same manner. At this time, the paddle portion 50b rubs against the sheet each time a sheet is discharged, so as the number of discharges increases, the rubbing surface wears down. Furthermore, when the same spot comes into contact with the sheet, that spot wears down locally and becomes more prone to bending.

[0046] As shown in Figure 8, a gap 11b is formed between the end of the loading tray 15 and the upright surface 11a of the device housing 11 so that the loading tray 15 can move smoothly up and down along the upright surface 11a. This gap 11b is such that even if a large amount of sheets are loaded onto the loading tray 15 and the loading tray 15 bends slightly, the tray will not come into contact with the upright surface 11a. In this embodiment, a gap 11b of about 5 mm is formed. Therefore, when the sheet-holding paddle 50 is in the sheet-holding position and the tip of the paddle portion 50b is in contact with the loading tray 15, if the loading tray 15 is raised until the sheet surface detection sensor Sn3 turns on, the elastically deformable paddle portion 50b may bend at the worn part and may enter the gap 11b as described above (see Figure 17(b)).

[0047] Furthermore, when the paddle portion 50b, which is made of rubber or the like, is new, it has a corner at its tip 50c, as shown in Figure 8(a). In this case, when the rising loading tray 15 comes into contact with the corner, the paddle portion 50b elastically deforms so as to bend outward (away from the gap 11b), as shown by the dashed line in Figure 8(a). Therefore, even if the sheet-holding paddle 50 bends, it will not enter the gap 11b. On the other hand, as shown in Figure 8(b), when the tip 50c of the paddle portion 50b wears down and the corner disappears, the paddle portion 50b that comes into contact with the rising loading tray 15 elastically deforms so as to bend inward (towards the gap 11b), making it easier for it to enter the gap 11b.

[0048] Therefore, in this embodiment, as shown in the flowchart of Figure 9, the drive control is performed so that the area in which the paddle portion 50b contacts the upper surface of the sheet on the loading tray 15 changes according to the number of times the sheet is discharged. This prevents wear on the sheet-holding paddle 50 from concentrating in a specific area and suppresses localized bending. Furthermore, the area in which the paddle portion 50b contacts the upper surface of the sheet on the loading tray 15 changes from the base side to the tip side of the paddle portion 50b, and is controlled so that wear on the tip corner is reduced.

[0049] Next, the lifting and lowering control of the paddle section 50b and the loading tray 15 in this embodiment, which is used to control sheet discharge as described above, will be explained with reference to the flowchart in Figure 9 and the operation diagrams in Figures 10 to 12.

[0050] First, when a bundle discharge mode job is received, an initial discharge start process is performed before sheet discharge occurs. This may be performed when the device is powered on. This initial discharge start process lowers the loading tray 15, moves the loading tray 15 to the home position upon detection by the loading tray HP sensor Sn1, resets the encoder 44 to position the loading tray 15, and then raises the loading tray 15 until the sheet surface detection sensor Sn3 turns on. After that, the loading tray 15 is lowered to a position at a distance L1 after the sheet surface detection sensor Sn3 turns off and stops. As a result, the sheet loading surface of the loading tray 15 moves to a sheet receiving position at a distance L1 lower than the position approximately opposite the sheet surface detection sensor Sn3. In addition, the sheet holding paddle 50 is stopped at a sheet holding position rotated by a predetermined amount from the home position (see Figure 10(a)).

[0051] In the state described above, a predetermined number of sheets are transported and aligned to the processing tray 14, and the stapling process is performed by the stapling unit 23. The stapled sheet bundle is then discharged by the discharge roller pair 31a, 31b (S101). If the discharged sheet bundle P is not the last sheet bundle in a series of continuously discharged sheet bundles, that is, if a sheet bundle is to be discharged immediately after the sheet bundle discharged to the loading tray 15, the sheet pressing paddle 50 is rotated to the sheet pressing position where the paddle portion 50b presses against the upper surface of the sheet on the loading tray 15 (see Figure 10(b)).

[0052] If the sheet surface detection sensor Sn3 turns on as a result of the previous sheet bundle P being discharged onto the loading tray 15, the loading tray 15 is lowered to a distance L1 after the sheet surface detection sensor Sn3 turns off, that is, until the top surface of the discharged sheet bundle P is at a distance L1 below the sheet surface detection sensor Sn3, in order to receive the next sheet bundle (see Figure 10(c)).

[0053] When the loading tray 15 is in the position lowered by the distance L1 (first position), the sheet-holding paddle 50 rotates to the sheet-holding position and elastically deforms upon contact with the upper surface of the sheet on the loading tray 15, at which point the paddle portion 50b comes into contact with the sheet at the base side (the side closer to the rotation axis 52) rather than the tip (first region a1).

[0054] In the above state, when the next sheet bundle is discharged onto the loading tray 15, the later sheet bundle is discharged onto the previous sheet bundle that has already been discharged onto the loading tray 15. However, because the previous sheet bundle is held down by the sheet holding paddle 50, it is not pushed out of the loading tray 15 by the discharged sheet bundle. In addition, one end of the discharged sheet bundle P abuts against the upright surface 11a of the device housing 11, restricting its movement in the direction opposite to the sheet discharge direction.

[0055] By performing the above discharge process on the sheet bundles that are continuously discharged onto the loading tray 15, the sheet bundles are sequentially stacked and discharged onto the loading tray 15.

[0056] The above discharge process is repeated, and the number of discharges with the loading tray 15 in the first position and the total number of discharges for the discharge job are counted each time a sheet is discharged. Then, until the number of discharges reaches 1 million, the loading tray 15 is moved to the first position, and the upper surface of the sheet on the tray is pressed down with the rotating sheet-pressing paddle 50 (S102~S104). As a result, the first region a1 of the paddle portion 50b, which rotates and rubs against the sheet each time a sheet is discharged, is mainly worn down.

[0057] When the number of sheet discharges exceeds 1 million, the control system changes the area of ​​the paddle portion 50b that contacts the upper surface of the sheet on the loading tray 15. Specifically, as shown in Figure 11, when discharge begins, the loading tray 15 is lowered to a position at a distance L2 after the sheet surface detection sensor Sn3 is turned off, and the sheet holding paddle 50 is stopped in the sheet holding position (see Figure 11(a)).

[0058] With respect to the loading tray 15 in the above state, the stitched sheet bundle is discharged onto the loading tray 15, and the sheet holding paddle 50 is rotated to the sheet holding position where the paddle portion 50b presses the upper surface of the sheet on the loading tray 15, and the sheet bundle P is pressed from above (see FIG. 11(b)).

[0059] As a result of the previous sheet bundle P being discharged onto the loading tray 15, if the sheet surface detection sensor Sn3 is turned on, the loading tray 15 is lowered until a distance L2 after the sheet surface detection sensor Sn3 is turned off in order to receive the next sheet bundle, that is, until the upper surface of the discharged sheet bundle P is at a position L2 below the sheet surface detection sensor Sn3 (see FIG. 11(c)).

[0060] The lowering distance L2 of the loading tray 15 is set to be a predetermined amount larger than the distance L1 (L1 < L2). When the loading tray 15 is at the position (second position) where it has been lowered by the distance L2, when the sheet holding paddle 50 rotates to the sheet holding position and elastically deforms when contacting the upper surface of the sheet on the loading tray 15, the paddle portion 50b contacts the sheet at a region (second region a2) that is closer to the base portion side than the tip and is also on the tip side of the aforementioned first region a1. That is, when the number of sheet discharges exceeds 1 million times, the region of the paddle portion 50b that contacts the sheet is changed from the base portion side to the tip side compared to when the number of discharges is 1 million times or less.

[0061] Repeat the above discharge, and count the number of discharges in the state where the loading tray 15 is at the second position and the total number of discharges of the discharge job. Then, until the number of discharges when moving the loading tray 15 to the second position and discharging reaches 1 million times, that is, until the number of times of the discharge job exceeds 1 million times and reaches 2 million times, the loading tray 15 is moved to the second position, and the upper surface of the sheet on the tray is pressed by the sheet holding paddle 50 rotated to the sheet holding position (S105 to S107). At this time, the paddle portion 50b that rotates and rubs against the sheet each time a sheet is discharged mainly wears in the second region a2.

[0062] When the number of discharges for moving and discharging the loading tray 15 to the second position exceeds 1,000,000 times, control is performed so that the area of the paddle portion 50b that abuts on the upper surface of the sheet on the loading tray 15 is changed. As shown in FIG. 12, at the start of discharge, the loading tray 15 is lowered to a position at a distance L3 after the sheet surface detection sensor Sn3 is turned off, and the sheet pressing paddle 50 is stopped at the sheet pressing position (see FIG. 12(a)).

[0063] With respect to the loading tray 15 in the above state, the bundled sheets that have been stitched are discharged onto the loading tray 15, and the sheet pressing paddle 50 is rotated until the paddle portion 50b rotates to the sheet pressing position where it presses the upper surface of the sheet on the loading tray 15, and the sheet bundle P is pressed from above (see FIG. 12(b)).

[0064] The distance L3 is set to be a predetermined amount larger than the distance L2 (L2 < L3). As shown in FIG. 12(b), when the upper surface of the sheet remains lower than the sheet surface detection sensor Sn3 and the sheet surface detection sensor Sn3 remains off even after discharging the sheet bundle P, the loading tray 15 is raised until the sheet surface detection sensor Sn3 is turned on (see FIG. 12(c)). Then, in order to receive the next sheet bundle, the loading tray 15 is lowered from when the sheet surface detection sensor Sn3 is turned off to the distance L3, that is, until the upper surface of the discharged sheet bundle P is at a position L3 below the sheet surface detection sensor Sn3 (see FIG. 12(d)).

[0065] When the loading tray 15 is at the position (third position) lowered by the distance L3 and the sheet pressing paddle 50 rotates to the sheet pressing position and elastically deforms when abutting on the upper surface of the sheet on the loading tray 15, the paddle portion 50b abuts on the sheet in a region (third region a3) on the tip side rather than the second region a2 described above.

[0066] The above discharge process is repeated, and the number of discharges while the loading tray 15 is in the third position and the total number of discharges for the discharge job are counted. The loading tray 15 is moved to the third position until the number of discharges with the loading tray 15 moved to the third position reaches 1 million, that is, from 2 million to 3 million discharge jobs, and the upper surface of the sheet on the tray is pressed down by the sheet pressing paddle 50 rotated to the sheet pressing position (S108~S110). At this time, the paddle portion 50b that rotates and rubs against the sheet with each sheet discharge mainly wears down in the third region a3.

[0067] As described above, the position of the loading tray 15 is changed so that each time the number of discharges reaches 1 million, the area in contact with the top surface of the sheet by the paddle portion 50b becomes the first area a1, the second area a2, and the third area a3. When the number of discharges after moving the loading tray 15 to the third position exceeds 1 million, the count values ​​for the number of discharges at the first position, the second position, and the third position are cleared (S111~S113), so that the area of ​​the paddle portion 50b in contact with the sheet repeats sequentially from the first area a1.

[0068] As a result, even if the sheet-holding paddle 50 is rotated each time a sheet is discharged, causing the paddle portion 50b to rub against the sheet, the wear area is dispersed, preventing localized wear. Therefore, bending caused by localized wear is suppressed, and the situation in which the paddle portion 50b enters the gap 11b can be prevented. In addition, since the wear of the paddle portion 50b moves from the base to the tip, the wear of the tip corner can be made slower than other parts.

[0069] Then, as shown in Figures 13(a)-(c), if a sheet bundle is removed from the loading tray 15 while the sheet bundle is being continuously discharged to the loading tray 15, or after the sheet bundle discharge has finished, the sheet surface detection sensor Sn3 turns off because the sheet bundle is gone. At this time, the control unit determines that the sheet bundle has been removed from the loading tray 15 and raises the loading tray 15 until the sheet surface detection sensor Sn3 turns on. If a sheet is removed from the loading tray 15 while the sheet bundle is being continuously discharged to the loading tray 15, the paddle part 50b rotates and is positioned in the pressing position for the discharge of the next sheet bundle. At this time, there is no sheet on the loading tray 15 and the tip of the paddle part 50b is facing downwards (Figure 13(b)). In this state, the control unit determines that the sheet bundle has been removed and raises the loading tray 15 until the sheet surface detection sensor Sn3 turns on. In this embodiment, localized wear of the paddle portion 50b is reduced, so the paddle portion 50b does not enter the gap 11b between the loading tray 15 and the vertical surface 11a as shown in Figure 17(b), and the loading tray 15 can be raised as shown in Figure 13(c).

[0070] In this embodiment, the sheet surface detection sensor Sn3 determines when a sheet has been removed from the loading tray 15. Specifically, if the sheet surface detection sensor Sn3 does not turn on even when a bundle of sheets is discharged onto the loading tray 15, it is determined that the sheet has been removed from the loading tray 15. Alternatively, if the sheet surface detection sensor Sn3 does not turn on even when one bundle of sheets is discharged, it may be determined that the sheet has been removed. For example, as shown in Figures 11 and 12, if the sheet receiving position is lower than the state in Figure 10, it may be determined that the sheet has been removed even when two bundles are discharged, if the sheet surface detection sensor Sn3 does not turn on.

[0071] [Second Embodiment] In the embodiment described above, an example was shown in which the position of the loading tray 15 is changed in order to change the area in which the paddle portion 50b contacts the upper surface of the sheet on the loading tray 15 according to the number of times the sheet is discharged. However, the contact point of the paddle portion 50b with respect to the sheet may also be changed by other configurations. For example, Figure 14 is a flowchart showing an example in which the area in which the paddle portion 50b contacts the upper surface of the sheet on the loading tray 15 is changed by changing the sheet pressing angle of the sheet pressing paddle 50.

[0072] In this embodiment, the position of the sheet's upper surface on the loading tray 15 is fixed during sheet discharge. Specifically, the sheet is lowered from the state where the sheet surface detection sensor Sn3 is ON until it turns OFF, and then stopped when it reaches a predetermined position, which is designated as the sheet receiving position. Therefore, the upper surface of the sheet discharged onto the loading tray 15 is always in a constant position.

[0073] On the other hand, the sheet pressing angle of the sheet pressing paddle 50 that presses down on the sheet on the loading tray 15 is changed according to the number of sheet discharges. In this embodiment, the number of discharges is counted each time a sheet is discharged, and until the number of discharges reaches 1 million, the sheet pressing paddle 50 is rotated to a position where the sheet pressing angle of the sheet pressing paddle 50 is θ1 to press down on the top surface of the sheet (see Figure 15(a)) (S201~S204). This angle θ1 is the angle made by the paddle portion 50b with respect to the vertical direction when the sheet pressing paddle 50 is rotated to the sheet pressing position, and at this time the elastically deformed paddle portion 50b comes into contact with the sheet in a first region a1. This first region a1 is the region closer to the base of the paddle portion 50b than to the tip.

[0074] Then, when the number of sheet ejection cycles exceeds 1 million, the sheet pressing paddle 50 is rotated to a position where the sheet pressing angle of the sheet pressing paddle 50 is θ2, pressing down on the upper surface of the sheet (see Figure 15(b)) (S205~S207). This angle θ2 is larger than the angle θ1 (θ1 < θ2), and when the sheet pressing paddle 50 is rotated to angle θ2, the elastically deformed paddle portion 50b comes into contact with the sheet in the second region a2. This second region a2 is a region closer to the tip than the first region.

[0075] Furthermore, when the number of sheet ejection cycles exceeds 2 million, the sheet pressing paddle 50 is rotated to a position where the sheet pressing angle of the sheet pressing paddle 50 is θ3, pressing down on the upper surface of the sheet (see Figure 15(c)) (S208~S210). This angle θ3 is larger than the angle θ2 (θ2 < θ3), and when the sheet pressing paddle 50 is rotated to angle θ3, the elastically deformed paddle portion 50b comes into contact with the sheet in the third region a3. This third region a3 is the region closer to the tip than the second region a2.

[0076] When the number of discharges with the sheet pressing angle at θ3 exceeds 1 million, the count values ​​for the number of discharges at the first angle θ1, the count values ​​for the number of discharges at the second angle θ2, and the count values ​​for the number of discharges at the third angle θ3 are cleared (S211~S213), so that the area of ​​the paddle portion 50b that contacts the sheet is repeated sequentially from the first area.

[0077] Even with the above configuration, the area in which the paddle portion 50b contacts the upper surface of the sheet on the loading tray 15 can be changed depending on the number of discharges.

[0078] In the embodiment described above, an example was shown in which stapled sheet bundles were discharged, but the same method can also be applied when unstapled sheets are discharged one by one to the loading tray 15.

[0079] In the embodiment described above, it was determined whether the sheet surface detection sensor Sn3 was on or off each time a sheet bundle was discharged, that is, whether or not a sheet bundle had been removed from the loading tray 15. However, in the case of sheet bundles that have been bound with a small number of sheets, for example, the determination may be made each time multiple sheet bundles are discharged, rather than each bundle.

[0080] Furthermore, although the above-described embodiment showed an example of discharging a stack of stapled sheets, the same method can be applied when discharging unstapled sheets one by one into the loading tray 15. In this case, similar to the case of a small number of sheets, the output of the sheet surface detection sensor Sn3 may be checked each time multiple sheets (for example, 15 sheets) are discharged, and if it is in the off state, it may be determined that the sheet has been removed.

[0081] Furthermore, in the embodiment described above, the removal of a sheet was determined by turning the sheet surface detection sensor Sn3 on or off, but other methods may be used to determine if a sheet has been removed. For example, a separate sensor capable of detecting the sheet surface could be provided below the sheet surface detection sensor Sn3, and when this removal detection sensor is turned off, it could be determined that a sheet on the loading tray 15 has been removed.

[0082] Furthermore, in the embodiments described above, the sheet processing apparatus B was configured to be placed within the internal space 4c of the image forming apparatus A. However, the sheet processing apparatus of the present invention may be configured, for example, to be mounted on the side of the image forming apparatus. Also, the sheet processing apparatus may be controlled by the image forming control unit 200 provided in the image forming apparatus A. That is, the control unit may be located within the sheet processing apparatus or within the image forming apparatus, as long as it is possible to control the sheet processing apparatus within the image forming system. [Explanation of symbols]

[0083] A...Image forming apparatus B...Sheet processing device M1 ... Tray lifting motor M2 ... Discharge roller motor M3...Seat retaining paddle motor M4 ... Conveyor motor S...Seat Sn1 ... Loading tray HP sensor Sn2 ... Paddle HP Sensor Sn3 ... Sheet surface detection sensor 11a...erecting surface 14… Processing tray 15…Loading tray 23… Staple binding unit 31a ... Upper discharge roller 31b ... Lower discharge roller 50...Seat retaining paddle 100 ... Sheet processing device control unit

Claims

1. A sheet processing unit that performs a predetermined process on the sheet, A discharge section for discharging the sheet, A loading section for loading sheets discharged by the aforementioned discharge section, comprising a loading section that can move up and down along an upright surface, A sheet surface detection sensor for detecting the height of the top surface of the loading section or the top sheet of the sheet bundle loaded in the loading section, A rotatable and elastically deformable pressing member is provided to press down on the upper surface of the sheet discharged into the loading section. A control unit that controls the raising and lowering of the loading section and the operation of the holding member, Equipped with, The control unit rotates the pressing member to a pressing position to press the upper surface of the first sheet discharged into the loading section when the second sheet is discharged to the loading section following the first sheet, moves the loading section so that the upper surface of the first sheet is at a height that can receive the second sheet, and repeats the operation of discharging the second sheet while the pressing member is in the pressing position. If it is determined that a sheet loaded in the loading section has been removed while continuously discharging sheets, the loading section will be raised until the sheet surface detection sensor detects the loading section or the sheet on the loading section. A sheet processing apparatus characterized by controlling the loading section and the pressing member so as to change the area in which the contact portion contacts the upper surface of the sheet on the loading section when the contact portion presses down on the sheet on the loading section, according to the number of rotations of the pressing member.

2. The sheet processing apparatus according to claim 1, characterized in that the control unit controls the raising and lowering of the loading section to change the height of the uppermost sheet of the sheet bundle loaded in the loading section when the pressing member presses down on the sheet, according to the number of rotations of the pressing member.

3. The sheet processing apparatus according to claim 1, characterized in that the control unit controls the amount of rotation of the pressing member from a reference position to a position that presses the sheet, according to the number of rotations of the pressing member.

4. An image forming unit that forms an image on a sheet, A sheet processing unit that performs predetermined processing on a sheet on which an image has been formed by the image forming unit, A discharge section for discharging the sheet, A loading section for loading sheets discharged by the aforementioned discharge section, comprising a loading section that can move up and down along an upright surface, A sheet surface detection sensor for detecting the height of the top surface of the loading section or the top sheet of the sheet bundle loaded in the loading section, A rotatable and elastically deformable pressing member is provided to press down on the upper surface of the sheet discharged into the loading section. A control unit that controls the raising and lowering of the loading section and the operation of the holding member, Equipped with, The control unit rotates the pressing member to a pressing position to press the upper surface of the first sheet discharged into the loading section when the second sheet is discharged to the loading section following the first sheet, moves the loading section so that the upper surface of the first sheet is at a height that can receive the second sheet, and repeats the operation of discharging the second sheet while the pressing member is in the pressing position. If it is determined that a sheet loaded in the loading section has been removed while continuously discharging sheets, the loading section will be raised until the sheet surface detection sensor detects the loading section or the sheet on the loading section. An image forming system characterized by controlling the loading section and the pressing member so as to change the area in which the contact portion contacts the upper surface of the sheet on the loading section when the contact portion presses down on the sheet on the loading section, according to the number of rotations of the pressing member.

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