Sheet processing device and image forming system

Abstract

To provide a sheet processing device capable of further increasing speed in shift discharge processing for discharging a sheet after moving the sheet in the shift direction.SOLUTION: In a sheet processing device, after the tip end of a sheet S passes between an upper discharge roller 230A and a lower discharge roller 230B and the rear end of the sheet S passes through pre-process rollers 211A and 212A, the sheet S is nipped by a pair of alignment plates 271A and 271B in a state where the sheet S is being moved in the first conveyance direction without raking the sheet S by a raking paddle 240A. In this state, the pair of alignment plates 271A and 271B are moved in the shift direction, and the shift operation of moving the position of the sheet S in the shift direction is performed. After that, the pair of alignment plates 271A and 271B are retracted in the width direction from the sheet S subjected to the shift operation, and the upper discharge roller 230A and the lower discharge roller 230B are moved to the nip position, followed by discharging the sheet onto a placement tray 300 by the upper discharge roller 230A and the lower discharge roller 230B.SELECTED DRAWING: Figure 23

Description

[Technical field]

[0001] The present invention relates to a sheet processing apparatus that performs a binding process on sheets, and an image forming system that includes the sheet processing apparatus. [Background technology]

[0002] Patent Document 1 describes a sheet processing device that is configured to perform a binding discharge process in which a sheet is transported to a processing tray, the sheet is switched back on the processing tray, the rear end of the sheet is abutted against a rear end regulating section, and the sheet is stapled and discharged to a stacking tray, and a switchbackless shift discharge process in which the sheet is moved in a shift direction intersecting the transport direction by a pair of alignment plates without switching back the sheet, and discharged to the stacking tray. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2023-20999 Summary of the Invention [Problem to be solved by the invention]

[0004] In the shift discharge process in which the sheet is moved in the shift direction and then discharged, it is desired to further increase the speed. An object of the present invention is to provide a sheet processing apparatus capable of performing the shift discharge process at a higher speed, and an image forming system equipped with the sheet processing apparatus. [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided a sheet conveying device including a first conveying section that conveys a sheet in a first conveying direction, a placement section that places the sheet conveyed by the first conveying section, an abutment section against which an upstream edge of the sheet on the placement section in the first conveying direction is abutted, a second conveying section that conveys the sheet in a second conveying direction in which the upstream edge of the sheet on the placement section in the first conveying direction faces the abutment section, and a pair of conveying sections that are disposed on both sides of the sheet abutted against the abutment section with respect to a width direction of the sheet that intersects with the first conveying direction and align the sheet abutted against the abutment section in the width direction. a pair of alignment plates for stapling a sheet bundle including a plurality of sheets aligned in the width direction by the pair of alignment plates; a processing section for performing a binding process on a sheet bundle including a plurality of sheets aligned in the width direction by the pair of alignment plates; a loading section disposed downstream in the first transport direction from the placement section and loading the sheets transported in the first transport direction by the first transport section; a pair of discharge rotating bodies for discharging the sheets transported in the first transport direction by the first transport section to the loading section; and a moving section which moves the sheet to a nip position where the sheet is nipped by the discharge rotors and a separation position where the pair of discharge rotors are separated, and by repeating the steps of: after the sheet is conveyed in the first conveying direction by the first conveying section, the sheet conveyed by the first conveying section is conveyed in the second conveying direction by the second conveying section on the placement section, the downstream end edge of the sheet in the second conveying direction is abutted against the abutment section, and the sheet is aligned at the binding position by the pair of alignment plates, the sheet is aligned at the binding position by the pair of alignment plates, and the sheet is aligned at the binding position by the pair of alignment plates. a binding discharge process in which the binding process is performed by a recording processing unit, and the plurality of sheets that have been subjected to the binding process are discharged to the stacking unit by the pair of discharge rotors; and a binding discharge process in which the first conveying unit conveys the sheets in the first conveying direction, and when, in a state in which the pair of discharge rotors are in the separated position, a downstream end in the first conveying direction of the sheet conveyed in the first conveying direction by the first conveying unit passes between the pair of discharge rotors and an upstream end in the first conveying direction of the sheet conveyed in the first conveying direction by the first conveying unit passes through the first conveying unit,A sheet whose upstream end in the first transport direction has passed through the first transport section is sandwiched between the pair of alignment plates while the sheet is moving in the first transport direction without being transported in the second transport direction by the second transport section, and the pair of alignment plates are moved in this state in a shift direction that is one of both sides in the width direction, thereby performing a shift operation for moving a position of the sheet whose upstream end in the first transport direction has passed through the first transport section in the shift direction, and after the shift operation by the pair of alignment plates, the pair of alignment plates are moved in the width direction away from the sheet that has been subjected to the shift operation. and a sorting and discharging process in which the first and second sheets are retracted from the stack and moved to the nip position by the pair of discharging rotors, and then the pair of discharging rotors are used to discharge sheets one by one to a shift position on the stacking unit, which is repeated multiple times to stack a first unbound sheet stack, and the sheets transported by the first transport unit are discharged one by one by the pair of discharging rotors to a position on the stacking unit shifted upstream from the shift position in the shift direction, without being transported in the second transport direction by the second transport unit, by the pair of discharging rotors, which is repeated multiple times to stack a second unbound sheet stack.

[0006] According to one aspect of the present invention, there is provided a sheet conveying device including a first conveying section that conveys a sheet in a first conveying direction, a placement section that places the sheet conveyed by the first conveying section, an abutment section against which an upstream edge of the sheet on the placement section in the first conveying direction is abutted, a second conveying section that conveys the sheet in a second conveying direction in which the upstream edge of the sheet on the placement section in the first conveying direction faces the abutment section, and a pair of conveying sections that are disposed on both sides of the sheet abutted against the abutment section with respect to a width direction of the sheet that intersects with the first conveying direction and align the sheet abutted against the abutment section in the width direction. a pair of alignment plates for stapling a sheet bundle including a plurality of sheets aligned in the width direction by the pair of alignment plates; a processing section for performing a binding process on a sheet bundle including a plurality of sheets aligned in the width direction by the pair of alignment plates; a loading section disposed downstream in the first transport direction from the placement section and loading the sheets transported in the first transport direction by the first transport section; a pair of discharge rotating bodies for discharging the sheets transported in the first transport direction by the first transport section to the loading section; and a moving section which moves the sheet to a nip position where the sheet is nipped by the discharge rotors and a separation position where the pair of discharge rotors are separated, and by repeating the steps of: after the sheet is conveyed in the first conveying direction by the first conveying section, the sheet conveyed by the first conveying section is conveyed in the second conveying direction by the second conveying section on the placement section, the downstream end edge of the sheet in the second conveying direction is abutted against the abutment section, and the sheet is aligned at the binding position by the pair of alignment plates, the sheet is aligned at the binding position by the pair of alignment plates, and the sheet is aligned at the binding position by the pair of alignment plates. a binding discharge process in which the binding process is performed by a recording processing unit, and the plurality of sheets that have been subjected to the binding process are discharged to the stacking unit by the pair of discharge rotors; and a binding discharge process in which the first conveying unit conveys the sheets in the first conveying direction, and when, in a state in which the pair of discharge rotors are in the separated position, a downstream end in the first conveying direction of the sheet conveyed in the first conveying direction by the first conveying unit passes between the pair of discharge rotors and an upstream end in the first conveying direction of the sheet conveyed in the first conveying direction by the first conveying unit passes through the first conveying unit,a shift operation for shifting a position of the sheet whose upstream end in the first conveying direction has passed through the first conveying section in the predetermined shift direction by moving one of the pair of alignment plates in the width direction in a predetermined shift direction that is a direction toward the other side in the width direction, without conveying the sheet whose upstream end in the first conveying direction has passed through the first conveying section in the second conveying direction by the second conveying section and while the sheet is moving in the first conveying direction, and after the shift operation, the one alignment plate is retracted in the width direction from the sheet that has been shifted; and a sorting and discharging process in which the pair of discharge rotors is moved to the nip position, and then the pair of discharge rotors discharges sheets to a shift position of the stacking unit, which is repeated a plurality of times to stack a first unbound sheet stack, and the sheets transported by the first transport unit are discharged one by one by the pair of discharge rotors to a position on the stacking unit shifted upstream from the shift position in the predetermined shift direction without being transported in the second transport direction by the second transport unit, which is repeated a plurality of times to stack a second unbound sheet stack. Effect of the Invention

[0007] According to the present invention, the shift discharge process can be performed at a further high speed. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of an image forming system according to a first embodiment. [Diagram 2] 1 is a schematic cross-sectional view of a sheet processing apparatus according to a first embodiment. [Diagram 3] 1 is a schematic perspective view showing a sheet processing apparatus according to a first embodiment with an upper cover removed; [Figure 4] FIG. 4 is a side view showing the upper discharge roller and the lower discharge roller in a first separated position according to the first embodiment. [Diagram 5] FIG. 4 is a side view showing the upper discharge roller and the lower discharge roller in a second separated position according to the first embodiment. [Figure 6]FIG. 2 is a plan view of a pair of alignment plates and their surrounding configuration according to the first embodiment, as viewed from above. [Figure 7] 3 is a plan view showing the pair of alignment plates and the surrounding configuration according to the first embodiment, as viewed from below. FIG. [Figure 8] FIG. 2A is a perspective view of a front-side alignment plate and its surrounding configuration according to the first embodiment, as viewed from below; FIG. [Figure 9] 5A to 5C are schematic diagrams illustrating a clamping position, a first retracted position, and a second retracted position of a pair of alignment plates according to the first embodiment. [Figure 10] 1A is a perspective view of the periphery of a processing tray in a home position of a sheet processing apparatus according to a first embodiment, and FIG. 1B is a schematic cross-sectional view of the sheet processing apparatus. [Figure 11] 5A is a diagram showing a state of a discharge roller, a state of a pick-up paddle, and a state of a trailing end drop-off member in a home position of the sheet processing apparatus according to the first embodiment, as viewed from the width direction. [Figure 12] FIG. 4 is a perspective view showing an engagement relationship between a trailing end dropping member and a sweeping paddle according to the first embodiment. [Figure 13] 1A is a perspective view of the periphery of a processing tray when the sheet processing apparatus according to the first embodiment discharges a sheet, and FIG. 1B is a schematic cross-sectional view of the sheet processing apparatus. [Figure 14] 5A is a diagram showing a state of a discharge roller, a state of a pick-up paddle, and a state of a trailing end drop-off member when a sheet is discharged from the sheet processing apparatus according to the first embodiment, as viewed from the width direction. [Figure 15] 1A is a perspective view of the periphery of a processing tray when the sheet processing apparatus according to the first embodiment picks up a sheet, and FIG. 1B is a schematic cross-sectional view of the sheet processing apparatus. [Figure 16] 5A is a diagram showing a state of a discharge roller, a state of a pick-up paddle, and a state of a trailing end drop-off member when the sheet processing apparatus according to the first embodiment picks up a sheet, as viewed from the width direction. [Figure 17] 4 is a table showing the correspondence between each motor and each component of the sheet processing apparatus according to the first embodiment. [Figure 18] FIG. 2 is a block diagram showing a control configuration of the sheet processing apparatus according to the first embodiment. [Figure 19] 5 is a flowchart showing an example of a control flow of the sheet processing apparatus according to the first embodiment. [Figure 20] 1A is a schematic diagram of a main part of a sheet processing apparatus in a home position of a switchback-less shift discharge process according to a first embodiment, and FIG. 1B is a schematic cross-sectional view of the configuration thereof. [Figure 21] 1A is a schematic diagram of a main part of a sheet processing apparatus when receiving a sheet in a switchback-less shift discharge process according to a first embodiment, and FIG. 1B is a schematic cross-sectional view of the configuration. [Figure 22] 1A is a schematic diagram of a main part of a sheet processing apparatus when an upper discharge roller is lowered in a switchback-less shift discharge process according to a first embodiment, and FIG. 1B is a schematic cross-sectional view of the configuration. [Figure 23] 1A is a schematic diagram of a main part of the sheet processing apparatus when an alignment plate moves in a switchback-less shift discharge process according to a first embodiment, and FIG. 1B is a schematic cross-sectional view of the configuration. [Figure 24] 1A is a schematic diagram of a main part of the sheet processing apparatus when a sheet is shifted by an alignment plate in a switchback-less shift discharge process according to a first embodiment, and FIG. 1B is a schematic cross-sectional view of the configuration. [Diagram 25] 1A is a schematic diagram of a main part of a sheet processing apparatus when a sheet is shifted in a switchback-less shift discharge process according to a first embodiment, as viewed from above; FIG. [Figure 26] 3A is a schematic diagram of a main part of the sheet processing apparatus when an alignment plate is retracted in a switchback-less shift discharge process according to the first embodiment, and FIG. 3B is a schematic cross-sectional view of the configuration. [Figure 27] 1A is a schematic diagram of a main part of a sheet processing apparatus when discharging a sheet in a switchbackless shift discharging process according to a first embodiment, and FIG. 1B is a schematic cross-sectional view of the configuration thereof. [Figure 28]1A is a schematic diagram of a main part of a sheet processing apparatus when sheet discharge in a switchbackless shift discharge process according to a first embodiment is completed, and FIG. 1B is a schematic cross-sectional view of the configuration. [Figure 29] FIG. 13 is a schematic cross-sectional view of the sheet processing apparatus according to the second embodiment when a trailing end dropping member is lowered in a switchback-less shift discharge process. [Diagram 30] 13A is a schematic diagram of a main part of a sheet processing apparatus when a sheet is shifted by an alignment plate in a switchback-less shift discharge process according to a third embodiment, and FIG. 13B is a schematic cross-sectional view of the configuration. [Diagram 31] FIG. 1 is a schematic cross-sectional view of the sheet processing device during binding and discharging processing in the first embodiment, in which (a) shows the state in which sheets are transported, (b) shows the state in which a sheet bundle is formed and aligned on the processing tray, and (c) shows the state in which the bound sheet bundle is discharged to the stacking tray. [Diagram 32] 13 is a perspective view showing a state in which an unbound sheet stack is formed on the stacking tray and moved in the shift direction. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] <First embodiment> The first embodiment will be described with reference to Figures 1 to 28. First, the schematic configuration of an image forming system according to the present embodiment will be described with reference to Figure 1.

[0010] [Image formation system] 1 is a cross-sectional view showing a schematic configuration of an image forming system according to the present embodiment. The image forming system 1000 includes an image forming apparatus 100 and a sheet processing apparatus 200. The image forming apparatus 100 may be a copier, printer, facsimile, or a multifunction machine having a plurality of these functions, and forms an image on a sheet such as paper or a plastic sheet. In this embodiment, the image forming apparatus 100 is an electrophotographic printer, and a sheet on which a toner image has been formed is discharged from a discharge port 101. The image forming apparatus 100 may be an inkjet image forming apparatus.

[0011] The image forming apparatus 100 of this embodiment includes an image forming apparatus main body 110 and an image reading device 120 arranged above the image forming apparatus main body 110. In the image forming apparatus main body 110, a toner image is formed on a sheet in an image forming section 103. The image forming section 103 of this embodiment forms a full-color toner image using toner of four colors, yellow (y), magenta (m), cyan (c), and black (k). For this reason, the image forming section 103 has a plurality of image forming stations that form toner images of each color. The configuration of the image forming stations of each color is the same except that the colors of the toner are different.

[0012] In the image forming station for each color, the surface of the photosensitive drum 10 is charged by a charging member 11 and exposed to light by an exposure device (not shown), thereby forming an electrostatic latent image on the photosensitive drum 10. This electrostatic latent image is then developed into a toner image by a developing device 12 using a developer. The toner image formed on the photosensitive drum 10 is primarily transferred onto an intermediate transfer belt 14 by a primary transfer roller 13. Residual toner remaining on the photosensitive drum 10 after the primary transfer is removed by a drum cleaner 15.

[0013] This cycle of charging, exposing, developing, primary transfer and drum cleaning is repeated in the same way at each image forming station, and the yellow, magenta, cyan and black toner images are transferred in sequence onto the intermediate transfer belt 14, forming a full-color toner image.

[0014] Meanwhile, the image forming apparatus 100 has a plurality of cassettes 20 for storing sheets. The sheets stored in each cassette 20 are conveyed to a sheet conveying path 22 by the rotation of a feed roller 21, and reach a registration roller 23. The registration roller 23 feeds the sheet to a secondary transfer section 17 formed by the intermediate transfer belt 14 and a secondary transfer roller 16 in synchronization with the toner image on the intermediate transfer belt 14. The multi-color toner images formed on the intermediate transfer belt 14 are secondarily transferred collectively onto the sheet in the secondary transfer section 17. Residual toner and paper powder remaining on the intermediate transfer belt 14 after the secondary transfer are removed by a belt cleaner 18.

[0015] The sheet that has passed through the secondary transfer unit 17 is transported to the fixing device 30, which serves as an image heating device. The fixing device 30 has a heating roller 31 and a pressure roller 32, which form a heating nip portion that sandwiches and transports the sheet between them. The sheet transported to the fixing device 30 is heated and pressurized in the heating nip portion, and the unfixed toner image is fixed onto the sheet. The sheet with the fixed toner image is transported through the discharge transport path 24 and is discharged by the discharge rollers 25 from the discharge port 101 to the outside of the machine, completing a series of image forming operations.

[0016] As described above, the image forming apparatus 100 of this embodiment includes the image forming apparatus main body 110 and the image reading device 120. The image reading device 120 reads an image on a document placed on the platen glass 122 by the image reading unit 121, and sends a read image signal to the image forming apparatus main body 110. In addition, an automatic document feeder (ADF) 123 that transports the document to the image reading unit 121 is disposed above the image reading device 120. The image reading device 120 can also read an image on a document fed by the automatic document feeder 123.

[0017] The image forming apparatus main body 110 has a first housing section 111 in which the image forming section 103 and the like are arranged, and a second housing section 112 in which the discharge conveying path 24 and the discharge rollers 25 are arranged, and the second housing section 112 is provided above the first housing section 111. The image reading device 120 is provided above the second housing section 112. In addition, the second housing section 112 is provided with an operation panel (not shown) so that a user can input instructions (printing conditions, mode settings, etc.) to the image forming apparatus 100 and the sheet processing apparatus 200.

[0018] In this embodiment, with such a configuration, there is an internal space 130 surrounded by the first housing 111, the second housing 112, and the image reading device 120. The image forming apparatus is configured so that a sheet is discharged from the discharge port 101 of the image forming apparatus main body 110 into the internal space 130. Also, a sheet processing device 200 and the like are detachably attached to this internal space 130. In this embodiment, the image forming system 1000 is configured by installing the sheet processing device 200, but other devices that perform sheet processing may also be installed.

[0019] The sheet processing apparatus 200 is connected to the discharge port 101 and receives the sheets discharged from the discharge port 101. Although the details will be described later, the sheet processing apparatus 200 can perform predetermined processing such as binding processing on the sheets.

[0020] [Sheet processing device] The configuration of the sheet processing apparatus 200 of this embodiment will be described with reference to Figs. 2 to 16. First, the overall configuration of the sheet processing apparatus 200 will be described with reference to Figs. 2 and 3. In the following description, the front side (front (F) side) is one side (the near side in Fig. 2, the near right side in Fig. 3) in the sheet width direction perpendicular to the sheet conveying direction, and is the side where an operator operates the image forming system 1000, for example, the side where an operation panel is installed. The rear side (rear (R) side) is the opposite side to the front side, and is the other side (the far side in Fig. 2, the far left side in Fig. 3) in the sheet width direction.

[0021] [Overall configuration of sheet processing device] The sheet processing apparatus 200 includes a conveying path 210A, pre-processing rollers 211A and 212A as a first conveying section, a processing tray 220 as a placement section, an upper discharge roller (nip member) 230A and a lower discharge roller 230B as a pair of discharge rotating bodies (discharge section), a pick-up paddle 240A as a second conveying section, a trailing end drop member 250A as a sheet drop section, an alignment section 270A and a return member 280 as first and second shift sections, a trailing end regulating member 290 as a striking section, a stacking tray 300 as a stacking section, and a discharge sheet pick-up paddle (sheet pressing paddle) 320A as a pick-up section. The sheet received from the image forming apparatus 100 is conveyed to the conveying path 210A.

[0022] The sheet conveyed from the conveying path 210A is directly discharged to the stacking tray 300 or placed on the processing tray 220 depending on the mode of processing the sheet. Note that direct discharge to the stacking tray 300 means that the sheet is discharged to the stacking tray 300 without being conveyed backward to a position on the processing tray 220 where stapling (binding) can be performed. In other words, the sheet processing device 200 has a mode in which the sheet stapled by the staple unit 400 is discharged to the stacking tray 300, and a mode in which the sheet is discharged to the stacking tray 300 without stapling by the staple unit 400. In this embodiment, the sheet can be aligned by a pair of alignment plates 271A and 271B of the alignment section 270A without being placed on the processing tray 220. Also, the sheet can be aligned on the processing tray 220, and the staple unit 400 can staple the sheet placed on the processing tray 220. Furthermore, the sheet or sheet stack placed on the processing tray 220 can be discharged onto the stacking tray 300 by a pair of discharge rotating bodies, such as an upper discharge roller 230A and a lower discharge roller 230B. The configuration of each section will be described in detail below.

[0023] [Transport path] The conveying path 210A is a path for conveying a sheet in a first conveying direction (a predetermined direction), and includes an upper guide 2101 for guiding the upper surface of the conveyed sheet, and a lower guide 2102 for guiding the lower surface of the sheet. In the conveying path 210A, pre-processing rollers 211A and 212A and upstream rollers (entrance rollers) 213a and 213b are arranged as a first conveying section (a pair of conveying rotating bodies). These are arranged in pairs so as to be spaced apart in the sheet width direction (arrow γ direction in FIG. 3) intersecting with the sheet conveying direction (first conveying direction, arrow β direction in FIG. 2 (left-right direction)).

[0024] The pre-processing rollers 211A and 212A are a first transport unit and a pair of transport rotating bodies that transport a sheet, and at least one of them rotates while sandwiching a sheet. The upstream rollers 213a and 213b are at least one of them rotates while sandwiching a sheet. The upstream rollers 213a and 213b are disposed at the entrance of the sheet processing apparatus 200, and receive the sheet transported from the upstream side of the sheet processing apparatus 200 and transport it to the transport path 210A. Then, the sheet that has passed through the transport path 210A reaches the pre-processing rollers 211A and 212A.

[0025] The pre-processing rollers 211A and 212A form a pre-processing nip portion 211a capable of nipping and transporting a sheet. The pre-processing nip portion 211a nips the sheet and transports it in the first transport direction, and the sheet is discharged from the transport path 210A. The pre-processing rollers 211A and 212A can be brought into contact with or separated from each other, or the nip pressure can be changed.

[0026] [Processing tray] The processing tray 220 as a placement unit is disposed downstream of the conveying path 210A in the sheet conveying direction (first conveying direction) and vertically below the conveying path 210A. The processing tray 220 is inclined with respect to the horizontal plane so that the upstream side in the first conveying direction is lower than the downstream side. The processing tray 220 temporarily places a sheet conveyed to the downstream side in the first conveying direction by the pre-processing rollers 211A and 212A. The processing tray 220 can also stack a plurality of sheets, and an alignment unit 270A aligns the sheets in the width direction and moves them in the width direction (shifts the sheets) on the processing tray 220. In this embodiment, "shift" refers to moving a sheet to the front side and / or rear side with respect to a sheet transported by the pre-processing rollers 211A and 212A with the sheet's center reference, and the shift discharge process described later includes a pattern in which a sheet is moved to the front side and discharged, and then another sheet is discharged to the rear side, and a pattern in which a sheet is discharged with the center reference and then another sheet is moved to the front side or rear side and discharged. Also, the shift discharge also includes discharging the next sheet by shifting it to the front side or rear side with respect to the already discharged sheet. In addition, at the upstream end of the processing tray 220 in the first transport direction, a rear end regulating member 290 is arranged as an abutting portion against which the upstream end edge (rear end of the sheet) in the first transport direction of the sheet placed on the processing tray 220 abuts. In addition, a part of the processing tray 220 (for example, the downstream end in the first transport direction) may protrude vertically upward from the transport path 210A.

[0027] Further, a staple unit 400 is disposed upstream of the processing tray 220 in the first transport direction as a processing section. The staple unit 400 performs a predetermined process of stapling (binding) the sheet stack that has been aligned in the width direction and has its rear end regulated by the processing tray 220. The staple unit 400 can change the staple position for the sheet stack, and moves according to the staple position. The predetermined process may be other processes such as punching other than stapling. The sheet or sheet stack placed on the processing tray 220 is discharged to the stacking tray 300 by upper discharge rollers 230A and lower discharge rollers 230B, as described later.

[0028] [Scraping paddle] The take-in paddle 240A as the second transport section transports (switchback transport) the sheet on the processing tray 220 in a second transport direction in which the upstream edge in the first transport direction of the sheet is directed toward the trailing end regulating member 290. The take-in paddle 240A has a paddle section 2401 as a rotating member, a paddle arm 2402 as a support section that supports the paddle section 2401, and a swing fulcrum 2403 that swingably supports the paddle arm 2402. That is, the paddle arm 2402 can swing up and down around the swing fulcrum 2403, and the paddle section 2401 is rotatably provided at the tip of the paddle arm 2402.

[0029] The pick-up paddle 240A can swing around a swing fulcrum 2403 between a return position where the paddle portion 2401 contacts the upper surface of the sheet on the processing tray 220 to convey the sheet in the second conveying direction, and an upper retreat position where the paddle portion 2401 retreats above the return position. The swing fulcrum 2403 is disposed upstream in the first conveying direction from a pre-processing nip portion 211a, which is a nip position where the pre-processing rollers 211A and 212A hold the sheet, and vertically above the pre-processing nip portion 211a. The paddle arm 2402 extends downstream in the first conveying direction from the swing fulcrum 2403, and the paddle portion 2401 is provided at its tip. As shown in FIG. 3, a pair of pick-up paddles 240A are disposed on both sides in the width direction of an upper discharge roller 230A, which will be described later.

[0030] [Rear end drop part] A pair of trailing end drop members 250A serving as sheet drop sections are provided on both sides of the pair of take-in paddles 240A. That is, the pair of trailing end drop members 250A are disposed on both sides of the take-in paddle 240A in the width direction, and move vertically in conjunction with the take-in paddle 240A as described below, thereby coming into contact with the upper surface of the upstream side of the sheet in the first conveying direction, and dropping the upstream end (rear end) of the sheet toward the processing tray 220. Note that the trailing end drop members 250A may be driven separately from the take-in paddle 240A.

[0031] The trailing end dropping member 250A has a rotation shaft 2501 as a rotation center downstream in the first transport direction from the pre-processing rollers 211A, 212A as a pair of transport rollers. The trailing end dropping member 250A extends from the rotation shaft 2501 to the upstream side in the first transport direction and is rotatable about the rotation shaft 2501 from an upper position above the pre-processing rollers 211A, 212A to a lower position below the pre-processing rollers 211A, 212A. By rotating from the upper position to the lower position, the trailing end dropping member 250A abuts against the sheet transported by the pre-processing rollers 211A, 212A from above and drops the sheet onto the processing tray 220 below. That is, the trailing end drop member 250A moves from a position above to a position below the sheet transported in the first transport direction by the pre-processing rollers 211A, 212A in the vertical direction, thereby dropping the upstream end (trailing end) in the first transport direction of the sheet transported in the first transport direction by the pre-processing rollers 211A, 212A toward the processing tray 220.

[0032] [Return part] The returning member 280 further transports the sheet transported by the take-in paddle 240A toward the trailing end regulating member 290 as described above, and brings the trailing end of the sheet into contact with the trailing end regulating member 290 to regulate the trailing end position of the sheet. Such a returning member 280 is formed of a knurled belt 281, and by rotating and driving the knurled belt 281, the returning member 280 further takes in the sheet transported upstream in the first transport direction by the take-in paddle 240A, and brings the trailing end into contact with the trailing end regulating member 290. The returning member 280 is movable between a contact position where it can contact the sheet and a retracted position retracted upward from the contact position, and moves to the contact position when the sheet is transported toward the trailing end regulating member 290, and moves to the retracted position when the sheet on the processing tray 220 is transported toward the stacking tray 300.

[0033] [Discharge roller] The upper discharge roller (upper discharge rotor) 230A and the lower discharge roller (lower discharge rotor) 230B constitute a pair of discharge rotors and a discharge section, and transport and discharge the sheet transported downstream in the first transport direction by the pre-processing rollers 211A, 212A downstream in the first transport direction from the processing tray 220. At least one discharge roller (discharge rotor) of the upper discharge roller 230A and the lower discharge roller 230B is movable between a nip position where the upper discharge roller 230A and the lower discharge roller 230B nip the sheet, and a separation position where the upper discharge roller 230A and the lower discharge roller 230B are separated from the nip position. In this embodiment, the upper discharge roller 230A, which is one of the discharge rotating bodies, can move to a nip position (contact position) where the sheet is nipped between the lower discharge roller 230B and the nip position, and a separation position where the upper discharge roller 230A and the lower discharge roller 230B are spaced apart from each other from the nip position by retracting upward from the nip position. That is, the upper discharge roller 230A functions as a nip member that nips the sheet between the lower discharge roller 230B at the nip position. The upper discharge roller 230A and the lower discharge roller 230B are arranged in pairs, spaced apart from each other in the width direction of the sheet. In this embodiment, they are arranged inside the pair of pick-up paddles 240A in the width direction. The lower discharge roller 230B may move in the vertical direction to move between the nip position and the separation position, or both discharge rollers 230A and 230B may move to move the nip position to the separation position.

[0034] The upper discharge roller 230A and the lower discharge roller 230B hold a sheet or a sheet bundle at a nip position, and the lower discharge roller 230B rotates to convey the held sheet or sheet bundle. The upper discharge roller 230A is a driven roller that rotates following the rotation of the lower discharge roller 230B, but may be driven. That is, in this embodiment, the upper discharge roller 230A is a driven rotating body, and the lower discharge roller 230B is a driving rotating body. The upper discharge roller 230A functions as a nip member that can hold a sheet between the upper discharge roller 230A and the lower discharge roller 230B at the nip position, but this nip member may be another rotating body such as a belt instead of a roller, or may be an abutting member that abuts against a sheet without rotating, such as a lever member.

[0035] The lower discharge roller 230B may be a rotating body such as a belt other than a roller. When the lower discharge roller 230B as the lower discharge rotating body is an endless belt, for example, the belt is stretched by a plurality of rollers, and the outer circumferential surface of the belt stretched by one of the rollers abuts against a nip member such as the upper discharge roller 230A to form the discharge nip portion 230a (see FIG. 13(b) described later). In this case, the rotation axis of the lower discharge rotating body is the rotation axis of the roller that stretches the belt at a position that forms the discharge nip portion 230a.

[0036] The upper discharge roller 230A can rotate around the rotation shaft 2301 between the nip position and the separation position. In other words, the upper discharge roller 230A can move up and down between the nip position and the separation position. As will be described in detail later, there are two separation positions, and the upper discharge roller 230A can move between a first separation position and a second separation position. The upper discharge roller 230A is provided at the tip of a discharge arm 2302 serving as a support. The rotation shaft 2301 is provided coaxially with the above-mentioned swing fulcrum 2403, and is disposed upstream in the first conveying direction from the pre-processing nip portion 211a where the pre-processing rollers 211A and 212A hold the sheet, and vertically above the pre-processing nip portion 211a. The discharge arm 2302 is extended from the rotation shaft 2301 to the downstream side in the first conveying direction, and the upper discharge roller 230A is provided at its tip. The rotation shaft 2301 does not have to be disposed coaxially with the swing fulcrum 2403, but in this embodiment, the rotation shafts of the upper discharge roller 230A and the pick-up paddle 240A are disposed coaxially.

[0037] The pivot shaft 2301 is disposed upstream in the first conveying direction of a discharge nip portion where the upper discharge roller 230A nips the sheet between the lower discharge roller 230B and the upper discharge roller 230A at the nip position. In addition, the upper discharge roller 230A is located vertically above the pre-processing nip portion 211a where the pre-processing rollers 211A and 212A nips the sheet at the separated position, and the pivot shaft 2301 is located vertically above the center of the upper discharge roller 230A at the separated position.

[0038] Since the positional relationship between the rotation shaft 2301 and the pre-processing nip portion 211a is defined as described above, the upper discharge roller 230A allows the sheet that has passed through the pre-processing nip portion 211a to move toward the stacking tray 300 when in the separated position. Meanwhile, the upper discharge roller 230A moves downward from the separated position toward the nip position by rotating counterclockwise in FIG. 2 about the rotation shaft 2301. Then, the upper discharge roller 230A moves to the nip position, whereby the sheet can be sandwiched between the upper discharge roller 230A and the lower discharge roller 230B.

[0039] [First and second separated positions] As described above, there are a first separation position and a second separation position for the upper discharge roller 230A. Fig. 4 shows a state in which the upper discharge roller 230A is at the first separation position, and Fig. 5 shows a state in which the upper discharge roller 230A is at the second separation position, in which the periphery of the upper discharge roller 230A and the lower discharge roller 230B are seen from the side (one side in the width direction of the sheet, the front side). As shown in Fig. 4, the first separation position is a position in which the upper discharge roller 230A is separated from the lower discharge roller 230B further from the nip position, and as shown in Fig. 5, the second separation position is a position in which the upper discharge roller 230A and the lower discharge roller 230B are separated from each other further from the nip position, and the interval between the upper discharge roller 230A and the lower discharge roller 230B is narrower than the first separation position.

[0040] Here, the distance between the upper discharge roller 230A and the lower discharge roller 230B in the first separation position is d1 (FIG. 4), and the distance between the upper discharge roller 230A and the lower discharge roller 230B in the second separation position is d2 (FIG. 5). In addition, the vertical height of the pair of alignment plates 271A and 271B at the same position as the rotation center O of the upper discharge roller 230A in the second separation position in the first conveying direction (arrow β direction) is d3 (FIG. 5). That is, as shown in FIG. 5, if a vertical line passing through the rotation center O of the upper discharge roller 230A is a virtual line L, the height of the alignment plates 271A and 271B at the part where the virtual line L passes is d3. The gap of the distance d2 in the second separation position at least partially overlaps with the range of the height d3 of the pair of alignment plates 271A and 271B when viewed from the width direction.

[0041] In this embodiment, the magnitude relationship of d1, d2, and d3 is d2 < d1 < d3. For example, d1 is 12.4 mm, d2 is 5 mm, and d3 is 13 mm. Also, when viewed from one side in the width direction of the sheet, a portion including the lower end portion in the vertical direction of the upper discharge roller 230A at the second separation position and a part of the space below it are at positions overlapping the pair of alignment plates 271A and 271B. Further, the gap between the lower end portions of the alignment plates 271A and 271B through which the virtual line L passes and the lower discharge roller 230B is small. Therefore, when the alignment plates 271A and 271B move in the width direction in a direction approaching the sheet, the sheet between the upper discharge roller 230A and the lower discharge roller 230B in the state at the second separation position will come into contact with the alignment plates 271A and 271B. In this embodiment, also at the first separation position, when viewed from one side in the width direction of the sheet, a portion including the lower end portion in the vertical direction of the upper discharge roller 230A and a part of the space below it are arranged to overlap the pair of alignment plates 271A and 271B. Also, when viewed from one side in the width direction of the sheet, a portion including the upper end portion in the vertical direction of the lower discharge roller 230B may also be configured to overlap the pair of alignment plates 271A and 271B.

[0042] [Alignment portion] Regarding the alignment portion 270A as the shift portion, in addition to FIGS. 2 and 3, FIGS. 6 to 9 will be used for explanation. The alignment portion 270A moves the sheet in the shift direction (width direction) by moving in the shift direction that intersects the first conveyance direction while being in contact with the edge along the first conveyance direction of the sheet conveyed to the downstream side in the first conveyance direction by the pre-treatment rollers 211A and 212A. Such an alignment portion 270A has a pair of alignment plates 271A and 271B as the first shift portion and the second shift portion arranged to face each other in the shift direction, as shown in FIGS. 6 and 7. Note that FIG. 6 is a plan view of the alignment portion 270A viewed from above in the vertical direction, and FIG. 7 is a plan view of the alignment portion 270A viewed from below in the vertical direction.

[0043] The pair of alignment plates 271A, 271B are disposed further downstream than the downstream end of the conveying path 210A in the first conveying direction, and align the sheet in the width direction by moving in the width direction and contacting the width direction edge of the sheet. In this embodiment, the alignment plates 271A, 271B are disposed on both sides of the width direction of the sheet placed on the processing tray 220, and are movable in the width direction. The pair of alignment plates 271A, 271B extend from the upstream side to the downstream side in the first conveying direction with respect to the upper discharge roller 230A and the lower discharge roller 230B. That is, the pair of alignment plates 271A, 271B are disposed so as to straddle the upper discharge roller 230A and the lower discharge roller 230B in the first conveying direction. Therefore, a part of the pair of alignment plates 271A, 271B including the downstream end in the first conveying direction is located downstream of the upper discharge roller 230A and the lower discharge roller 230B in the first conveying direction. The pair of alignment plates 271A and 271B have the same configuration.

[0044] As shown in Figs. 6 and 7, the pair of alignment plates 271A and 271B are moved in the shift direction by the driving of a front side (F side) alignment plate moving motor MT16 and a rear side (R side) alignment plate moving motor MT17 as a driving unit. That is, a pinion gear 2711 is provided on the driving shaft of the F side alignment plate moving motor MT16 and the R side alignment plate moving motor MT17. Also, a rack gear 2712 is provided on each of the alignment plates 271A and 271B. The pinion gear 2711 and the rack gear 2712 are meshed with each other. The rack gear 2712 is arranged across the width direction, and moves along the width direction as the pinion gear 2711 rotates. Also, the pair of alignment plates 271A and 271B are guided along a guide shaft 2713 arranged along the width direction.

[0045] As a result, by driving the F-side alignment plate moving motor MT16, the alignment plate 271A on the front side (lower side in Figs. 6 and 7) can be moved in the width direction, and by driving the R-side alignment plate moving motor MT17, the alignment plate 271B on the rear side (upper side in Figs. 6 and 7) can be moved in the width direction. That is, in this embodiment, the alignment plates 271A and 271B can be moved independently.

[0046] Of such a pair of alignment plates 271A, 271B, in the shift discharge process described below, the alignment plate 271B on the upstream side in the shift direction (one side in the width direction, the rear side in this embodiment) is referred to as a first shift section, and the alignment plate 271A on the downstream side in the shift direction (the other side in the width direction, the front side in this embodiment) is referred to as a second shift section. Also, the motor that drives the first shift section is referred to as a first drive section, and the motor that drives the second shift section is referred to as a second drive section.

[0047] As shown in FIG. 8(a), the alignment plates 271A and 271B are formed so that the width in the vertical direction is wider on the downstream side in the first conveying direction. That is, the alignment plates 271A and 271B have a first plate portion 2701 on the downstream side in the first conveying direction, and a second plate portion 2702 formed so as to be continuous with the first plate portion 2701 on the upstream side in the first conveying direction. Although only the alignment plate 271A is shown in FIG. 8(a), the alignment plate 271B is also similar. The first plate portion 2701 has a larger area in the vertical direction than the second plate portion 2702 so that it can abut against the sheet even if the leading end side of the conveyed sheet is curled upward or downward. On the other hand, the second plate portion 2702 is formed so that the height in the vertical direction is lower than that of the first plate portion 2701 so that it does not interfere with the trailing end dropping member 250A even if the trailing end dropping member 250A is located at a lower position. Additionally, the upper edge of the second plate portion 2702 is inclined so as to become lower toward the upstream side in the first transport direction.

[0048] The first plate portion 2701 is formed so as to straddle the upper discharge roller 230A and the lower discharge roller 230B from the upstream side to the downstream side in the first transport direction. This allows at least the first plate portion 2701 to come into contact with the sheet even when the sheet is discharged by a switchbackless shift discharge process, which is one of the shift discharge processes described later. The second plate portion 2702 is located on the processing tray 220 and is formed continuously with the first plate portion 2701 in the first transport direction. This allows at least the second plate portion 2702 to come into contact with the sheet placed on the processing tray 220 by a switchback shift discharge process, which is one of the shift discharge processes described later.

[0049] The first plate portion 2701 also has a curl pressing portion 2703. The curl pressing portion 2703 is provided vertically above the discharge nip portion 230a (see FIG. 13(b) described later), which is a nip position where the upper discharge roller 230A and the lower discharge roller 230B pinch the sheet, so as to straddle from the upstream side to the downstream side in the first conveying direction, and presses the leading edge of the sheet curled upward. In this embodiment, the curl pressing portion 2703 is an uneven portion formed on the inside in the width direction (the side that abuts against the sheet) from the upper end of the first plate portion 2701, and the leading edge of the curled sheet in the width direction is caught by the curled sheet, thereby pressing the leading edge of the sheet.

[0050] The alignment portion 270A of this embodiment further includes a biasing spring 2714 as a biasing portion for biasing one (front side) alignment plate 271A of the pair of alignment plates 271A and 271B having such a configuration toward the other (rear side) alignment plate 271B. As shown in FIGS. 8(a) and 8(b), the front side alignment plate 271A is supported via a support portion 2715 fixed to the alignment plate 271A so as to be movable in the width direction relative to the guide shaft 2713. Meanwhile, the front side rack gear 2712 is supported via a support portion 2716 fixed to the rack gear 2712 so as to be movable in the width direction relative to the guide shaft 2713. Then, a biasing spring 2714, which is a compression spring, is disposed between a part of the support portion 2715 and a part of the support portion 2716.

[0051] More specifically, the support portion 2716 of the rack gear 2712 is fitted to the guide shaft 2713 by a pair of fitting portions 2716a and 2716b spaced apart from each other. On the other hand, the support portion 2715 of the alignment plate 271A is fitted to the guide shaft 2713 by a pair of fitting portions 2715a and 2715b spaced apart from each other. The fitting portion 2715a on the inner side (rear side) of the width direction of the alignment plate 271A is arranged to be located outside (front side) in the width direction of the fitting portion 2716a on the inner side (rear side) of the width direction of the rack gear 2712, and the fitting portion 2715b on the outer side of the width direction is located outside of the fitting portion 2716b in the width direction. In addition, a biasing spring 2714 is arranged in a compressed state between the fitting portion 2715a of the alignment plate 271A and the fitting portion 2716b of the rack gear 2712. As a result, when the alignment plate 271A is pushed to the front side by the sheet, the biasing spring 2714 is compressed and the alignment plate 271A moves to the front side relative to the rack gear 2712. In this state, the alignment plate 271A pushes the sheet to the rear side due to the elastic restoring force of the biasing spring 2714.

[0052] In this embodiment, as shown in FIG. 9, the pair of alignment plates 271A and 271B can move to an alignment position (not shown) for aligning the sheet S in the width direction, a clamping position, a first retracted position, and a second retracted position. In addition to these positions, the pair of alignment plates 271A and 271B can also move to a receiving position (not shown) for receiving the sheet on the processing tray 220. The alignment position is a position for aligning the sheet S in the width direction that is abutted against the trailing end regulating member 290 in a switchback-shift discharge process described later. The clamping position is a position for clamping the sheet S in a switchbackless shift discharge process described later. The first retracted position is a position where the pair of alignment plates 271A and 271B are retracted from both ends of the sheet S in the width direction from the clamping position. The second retracted position is a position where the pair of alignment plates 271A and 271B are retracted further from both ends of the sheet S in the width direction from the first retracted position. For example, the alignment position is a position where the pair of alignment plates 271A, 271B are substantially at the same position as both ends of the sheet in the width direction, and may be the same position as the clamping position, or may be a position slightly retreated from both ends of the sheet in the width direction from the clamping position. The clamping position is a position where the pair of alignment plates 271A, 271B abut against both ends of the sheet in the width direction. The first retreat position is a position where the pair of alignment plates 271A, 271B are retreated 3 mm from both ends of the sheet in the width direction. The second retreat position is a position where the pair of alignment plates 271A, 271B are retreated 5 mm from both ends of the sheet in the width direction. The receiving position is a position where the pair of alignment plates 271A, 271B are retreated 10 mm from both ends of the sheet in the width direction.

[0053] The first retraction position is a position where the distance from both ends of the width direction of the sheet being conveyed is reduced in order to prevent the sheet from being skewed when the sheet is discharged by the upper discharge roller 230A and the lower discharge roller 230B. The second retraction position prevents the sheet from contacting the pair of alignment plates 271A and 271B after the sheet leaves the discharge nip portion 230a formed by the upper discharge roller 230A and the lower discharge roller 230B. After the sheet leaves the discharge nip portion 230a, the sheet is not nipped by the rollers, etc., so if the edge in the width direction comes into contact with at least one of the pair of alignment plates 271A and 271B, there is a risk that the sheet will be tilted due to the influence. For this reason, in this embodiment, after the rear end of the sheet leaves the discharge nip portion 230a, the pair of alignment plates 271A and 271B are moved to the second retraction position.

[0054] In addition, the first retracted position may be such that the positions of the pair of alignment plates 271A, 271B are slightly different from each other within a range where the effect of suppressing skew of the sheet can be obtained. Similarly, in the second retracted position, the positions of the pair of alignment plates 271A, 271B may be slightly different from each other within a range where the sheet does not contact the pair of alignment plates 271A, 271B. In addition, the distance from both ends of the sheet in the width direction at each position may be other than the above-mentioned values ​​as long as the above-mentioned requirements are satisfied.

[0055] [Loading tray] As described above, the stacking tray 300 as a stacking section stacks sheets discharged by the upper discharge roller 230A and the lower discharge roller 230B. As shown in Figs. 2 and 3, the stacking tray 300 is provided downstream of the processing tray 220 in the first transport direction and is movable vertically downward. The stacking tray 300 is inclined with respect to the horizontal plane so that the upstream side in the first transport direction is lower than the downstream side. The stacking tray 300 is supported movably in the vertical direction along rails arranged in the vertical direction, for example, and is raised and lowered by driving a stacking tray lifting motor MT20 (Fig. 17) as a lifting means.

[0056] At the upstream end of the stacking tray 300 in the first transport direction, there are provided an upright surface 310a as a stacking side regulating means for regulating the upstream end (rear end) in the first transport direction of the sheet or sheet bundle stacked on the stacking tray 300, and a rear end presser 310b for pressing the rear end of the sheet abutting against the upright surface 310a. The rear end presser 310b is inclined more toward the downstream side in the first transport direction as it goes upward, so that even if the rear end of the sheet is curled upward, it can be pressed by this rear end presser 310b.

[0057] Further, the discharge sheet take-in paddle 320A is provided coaxially with the rotation axis of the lower discharge roller 230B. The rotation axis 3201 (see FIG. 2) of the discharge sheet take-in paddle 320A does not have to be coaxial with the rotation axis of the lower discharge roller 230B. The rotation axis 3201 of the discharge sheet take-in paddle 320A may be provided between the discharge nip portion 230a (see FIG. 13(b) described later) of the upper discharge roller 230A and the lower discharge roller 230B as a pair of discharge rotors and the standing surface 310a as a loading side abutment portion provided on the upstream side of the loading tray 300 in the first transport direction in the vertical direction. In this embodiment, as shown in FIG. 2, the rotation axis 3201 of the discharge sheet take-in paddle 320A is disposed between the downstream end of the processing tray 220 in the first transport direction and the upper end of the standing surface 310a in the vertical direction.

[0058] The stacking tray 300 can be raised and lowered by the stacking tray lifting motor MT20 between a first stacking position and a second stacking position lower than the first stacking position. The second stacking position is a position where the stacking tray 300, which has been lowered when discharging sheets onto the stacking tray 300, switches to an upward movement. When discharging sheets, the stacking tray 300 is raised and lowered, and the discharged sheet pick-up paddle 320A rotates, and the sheet on the stacking tray 300 (on the stacking section) is transported (picked up) in a third transport direction in which the upstream edge in the first transport direction faces the standing surface 310a. Then, the upper surface of the sheet on the stacking tray 300 or a sheet bundle consisting of multiple sheets is pressed down by the discharged sheet pick-up paddle 320A.

[0059] [Drive configuration of each part] Next, the drive configuration of the upper discharge roller 230A, the pick-up paddle 240A, and the trailing end drop member 250A will be described with reference to Figs. 10(a) to 16(c). In this embodiment, the upper discharge roller 230A, the pick-up paddle 240A, and the trailing end drop member 250A are configured to work in conjunction with each other. As shown in Fig. 10(a), the drive configuration 600 includes a processing motor 610 (MT12, Fig. 17) as a drive source, a drive transmission mechanism 611, a rotating shaft 612, and a cam mechanism 613. The processing motor 610 can rotate forward and backward, and the drive of the processing motor 610 is transmitted to the rotating shaft 612 via the drive transmission mechanism 611. In this embodiment, the drive transmission mechanism 611 is configured with a gear train, but other drive transmission configurations, such as a configuration in which the drive is transmitted by a belt, may be used.

[0060] The rotating shaft 612 is disposed in the width direction above the upper discharge rollers 230A, the pick-up paddles 240A, and the trailing-end dropping member 250A. The cam mechanism 613 is operated by the rotation of the rotating shaft 612. The cam mechanism 613 has a first cam member 620 and a second cam member 630 which rotate together with the rotating shaft 612. The first cam member 620 is disposed between the pair of upper discharge rollers 230A, and operates the upper discharge rollers 230A. The second cam members 630 are provided adjacent to each of the pair of pick-up paddles 240A, and operate the pick-up paddles 240A and the trailing-end dropping member 250A.

[0061] As shown in Fig. 11(a), the first cam member 620 has a groove 621 formed on the inside thereof into which the protrusion 2303 provided on the discharge arm 2302 of the upper discharge roller 230A can enter. The groove 621 has an outer peripheral surface, i.e., an inner peripheral surface of the first cam member 620, as an inner cam surface 622. The inner cam surface 622 is a cam surface whose distance from the rotation center of the rotation shaft 612 varies depending on the phase in the rotation direction. The first cam member 620 also has an outer peripheral surface formed as an outer cam surface 623. The outer cam surface 623 is also a cam surface whose distance from the rotation center of the rotation shaft 612 varies depending on the phase in the rotation direction.

[0062] In addition to the above-mentioned protrusion 2303, the discharge arm 2302 of the upper discharge roller 230A has an abutment portion 2304 that can abut against an outer cam surface 623 of the first cam member 620. The first cam member 620 rotates together with the rotating shaft 612 to change the abutment position (phase) between the inner cam surface 622 and the protrusion 2303 or separate them, and to change the abutment position (phase) between the outer cam surface 623 and the abutment portion 2304 or separate them, thereby rotating the upper discharge roller 230A around the rotating shaft 2301 between the nip position and the first and second separated positions, as described below.

[0063] As shown in FIG. 11B, the second cam member 630 has a groove 631 formed on the inside thereof into which the first protrusion 2404 provided on the paddle arm 2402 of the pick-up paddle 240A can enter. The groove 631 has an outer peripheral surface, i.e., an inner peripheral surface of the second cam member 630, as an inner cam surface 632. The inner cam surface 632 is a cam surface whose distance from the center of rotation of the rotating shaft 612 varies depending on the phase in the rotation direction. The second cam member 630 rotates together with the rotating shaft 612 to change the contact position (phase) between the inner cam surface 632 and the first protrusion 2404, thereby rotating the pick-up paddle 240A around the swing fulcrum 2403 between a return position and an upper retracted position, as described below.

[0064] 11(c) and 12, a support portion 2406 that swings around a swing fulcrum 2403 together with the paddle arm 2402 of the pick-up paddle 240A and supports an end of the rotation shaft 2401a of the paddle portion 2401 is provided with a second protrusion 2405 that can enter an engagement recess 2502 formed in the trailing end dropping member 250A. When the pick-up paddle 240A rotates, the engagement recess 2502 abuts against or separates from the second protrusion 2405, thereby rotating the trailing end dropping member 250A between an upper position and a lower position around the rotation shaft 2501 in conjunction with the rotation of the pick-up paddle 240A. The driving of the upper discharge roller 230A, the pick-up paddle 240A, and the trailing end dropping member 250A will be specifically described below.

[0065] [Home position] 10(a) to 11(c) show the home positions (HP) of the upper discharge roller 230A, the pick-up paddle 240A, and the trailing end drop-off member 250A. At the home positions, as shown in FIGS. 10(a) and 10(b), the upper discharge roller 230A is in the first separated position, the pick-up paddle 240A is in the upper retracted position, and the trailing end drop-off member 250A is in the upper position.

[0066] In this state, as shown in FIG. 11(a), the protrusion 2303 of the upper discharge roller 230A abuts at a position close to the center of the rotation shaft 612 of the inner cam surface 622 of the first cam member 620, so that the upper discharge roller 230A is supported by the first cam member 620.

[0067] Furthermore, as shown in FIG. 11(b), the first protrusion 2404 of the sweeping paddle 240A abuts at a position close to the center of the rotation shaft 612 of the inner cam surface 632 of the second cam member 630, thereby supporting the sweeping paddle 240A on the second cam member 630.

[0068] Furthermore, as shown in FIG. 11(c), the engagement recess 2502 of the trailing end dropping member 250A abuts against the second protrusion 2405 of the sweeping paddle 240A, so that the trailing end dropping member 250A is supported by the sweeping paddle 240A via the second protrusion 2405.

[0069] [Upper ejection roller lowering] Next, the operation of moving the upper discharge roller 230A from the home position (first separated position) to the nip position will be described with reference to Fig. 13(a) to Fig. 14(c). When the processing motor 610 is driven to rotate the rotating shaft 612 in a first direction (counterclockwise in Fig. 14(a) and (b)) in order to lower the upper discharge roller 230A from the home position, the first cam member 620 also rotates in the same direction, and the protrusion 2303 moves along the inner cam surface 622. The inner cam surface 622 is formed so that the distance from the center of the rotating shaft 612 increases when the inner cam surface 622 rotates counterclockwise from the home position. Therefore, this operation causes the upper discharge roller 230A to descend.

[0070] Next, when the upper discharge roller 230A moves to the nip position and comes into contact with the lower discharge roller 230B, as shown in Fig. 14(a), the inner cam surface 622 of the first cam member 620 separates from the protrusion 2303, and the outer cam surface 623 comes into contact with the contact portion 2304. By bringing the outer cam surface 623 into contact with the contact portion 2304 in this manner, the upper discharge roller 230A is pressed toward the lower discharge roller 230B, and a predetermined nip pressure is applied between these rollers.

[0071] At this time, the second cam member 630 also rotates together with the rotating shaft 612, but as shown in FIG. 14(b), the distance from the center of the rotating shaft 612 to the position where the inner cam surface 632 abuts against the first protrusion 2404 is approximately the same as the distance at the home position. Therefore, even if the second cam member 630 rotates, the pick-up paddle 240A is maintained at the home position. Since the pick-up paddle 240A is maintained at the home position, the trailing end dropping member 250A is also maintained at the home position, as shown in FIG. 14(c). That is, in this state, as shown in FIG. 13(b), the upper discharge roller 230A moves to the nip position, but the pick-up paddle 240A and the trailing end dropping member 250A are maintained at the home position.

[0072] When the upper discharge roller 230A is raised, the processing motor 610 is driven to rotate the rotary shaft 612 in a second direction opposite to the first direction (clockwise in Figs. 14(a) and (b)). Then, the first cam member 620 rotates together with the rotary shaft 612 in the same direction, and the protrusion 2303 moves along the inner cam surface 622, raising the upper discharge roller 230A. Then, it returns to the home position shown in Fig. 11(a).

[0073] 11(b) and (c) from the state of FIG. 14(b) and (c), the first protrusion 2404 moves along the inner cam surface 632 of the second cam member 630, but the inner cam surface 632 is formed so that the distance from the center of the rotation shaft 612 to the position where the inner cam surface 632 abuts against the first protrusion 2404 does not change. Therefore, the pick-up paddle 240A remains in the home position. Since the pick-up paddle 240A is maintained in the home position, the trailing end dropping member 250A also remains in the home position.

[0074] [Lowering of the raking paddle and rear end drop member] Next, the operation of moving the pick-up paddle 240A and the trailing end dropping member 250A from the home position (upper retracted position, upper position) to the return position and the lower position will be described with reference to Figs. 15(a) to 16(c). In order to lower the pick-up paddle 240A and the trailing end dropping member 250A from the home position, when the processing motor 610 is driven to rotate the rotating shaft 612 in a second direction (clockwise in Figs. 16(a) and 16(b)) opposite to the first direction, the first cam member 620 also rotates in the same direction, and the protrusion 2303 moves along the inner cam surface 622. The inner cam surface 622 is formed so that the distance from the center of the rotating shaft 612 does not change substantially even when the inner cam surface 622 rotates clockwise from the home position. Therefore, the upper discharge roller 230A is maintained at the home position as shown in Fig. 16(a).

[0075] Meanwhile, the second cam member 630 also rotates in the same direction together with the rotating shaft 612, and the first protrusion 2404 moves along the inner cam surface 632. The inner cam surface 632 is formed so that when it rotates clockwise from the home position, it becomes more distant from the center of the rotating shaft 612. Therefore, this action causes the sweeping paddle 240A to descend and move to the return position.

[0076] At this time, the trailing end dropping member 250A also descends together with the pick-up paddle 240A. In this embodiment, the trailing end dropping member 250A has a positioning portion 2503 that is positioned at the lower position by engaging with the upper guide 2101 of the conveying path 210A when it rotates from the upper position to the lower position. The positioning portion 2503 is provided at the upper end of a protruding portion 2504 that is provided to protrude upward from the tip (upstream end in the first conveying direction) of the trailing end dropping member 250A. The protruding portion 2504 also has a role of regulating the leading end of the sheet conveyed toward the pre-processing nip portion 211a on the upstream side in the first conveying direction of the pre-processing nip portion 211a when the trailing end dropping member 250A is in the lower position.

[0077] The positioning portion 2503 is an engagement portion provided on the upper end of the protrusion 2504 so as to be able to engage with the upper guide 2101, and by abutting against the upper surface of the upper guide 2101, it prevents the trailing end dropping member 250A from descending any further. The engagement recess 2502 is formed so as to be separated from the second protrusion 2405 in this state. Therefore, the trailing end dropping member 250A is disengaged from the sweeping paddle 240A, and is positioned at a lower position by the positioning portion 2503.

[0078] As a result, even if the pick-up paddle 240A reaches the return position, the trailing end dropping member 250A is not lowered any further and is positioned at the lower position due to the engagement between the positioning portion 2503 and the upper guide 2101. In this state, as shown in Fig. 15(b), the pick-up paddle 240A and the trailing end dropping member 250A move to the return position and the lower position, and the upper discharge roller 230A is located at the home position.

[0079] The above-mentioned protrusion 2504 and positioning portion 2053 shown in Fig. 16(c) are omitted in Fig. 1 to Fig. 15(b). Such protrusion 2504 and positioning portion 2053 may be omitted, in which case a separate positioning mechanism may be provided to position the trailing-end dropping member 250A at the lower position. For example, positioning may be performed by engaging the engagement recess 2502 with the second protrusion 2405 at the lower position.

[0080] When lifting the scavenging paddle 240A and the trailing-end dropping member 250A, the motor 610 is driven to rotate the rotating shaft 612 in a first direction (counterclockwise in FIGS. 16(a) and (b)). Then, the second cam member 630 rotates together with the rotating shaft 612 in the same direction, the first protrusion 2404 moves along the inner cam surface 632, and the scavenging paddle 240A lifts. At this time, slightly after the scavenging paddle 240A starts to lift, the second protrusion 2405 re-engages with the engagement recess 2052, and this engagement also lifts the trailing-end dropping member 250A. That is, the pick-up paddle 240A can rise independently by the gap between the second protrusion 2405 when the pick-up paddle 240A is in the return position and the portion of the engagement recess 2502 located above the second protrusion 2405, and when the pick-up paddle 240A has risen by this gap, the trailing end dropping member 250A is still in the lower position. Then, when the second protrusion 2405 rises by this gap and engages with the engagement recess 2502, the trailing end dropping member 250A starts to rise with a delay from the pick-up paddle 240A. As a result, the pick-up paddle 240A and the trailing end dropping member 250A return to the home positions shown in Figures 10(a) to 11(c).

[0081] 11(a) from the state of Fig. 16(a), the protrusion 2303 moves along the inner cam surface 622 of the first cam member 620, but the inner cam surface 622 is formed so that the distance from the center of the rotation shaft 612 to the position where the inner cam surface 622 abuts against the protrusion 2303 does not change at this time. Therefore, the upper discharge roller 230A remains maintained at the home position.

[0082] In this embodiment, when the rotating shaft 612 is rotated from the home position in the counterclockwise direction in Figures 11(a) to 11(c), the upper discharge roller 230A descends, and the pick-up paddle 240A and the trailing end drop-off member 250A are maintained in the home position. On the other hand, when the rotating shaft 612 is rotated from the home position in the clockwise direction in Figures 11(a) to 11(c), the upper discharge roller 230A is maintained in the home position, and the pick-up paddle 240A and the trailing end drop-off member 250A descend.

[0083] 14(a) to 14(c), the upper discharge roller 230A is raised, and the pick-up paddle 240A and the trailing end drop-off member 250A are maintained in their home positions. On the other hand, when the rotation shaft 612 is rotated in the counterclockwise direction in FIGS. 16(a) to 16(c), the upper discharge roller 230A is maintained in its home position, and the pick-up paddle 240A and the trailing end drop-off member 250A are raised, while the pick-up paddle 240A and the trailing end drop-off member 250A are in their return and lower positions.

[0084] Fig. 17 shows the relationship between each motor and each component. From the left, the columns in Fig. 17 show the number, motor name, driving parts, operation, direction of operation during forward rotation, and direction of operation during reverse rotation. In Fig. 17, the processing motor MT12 is the processing motor 610 described above. As is clear from Fig. 17, the conveying motor MT11 drives either of the upstream rollers (inlet rollers) 213a and 213b, either of the pre-processing rollers 211A and 212A, the pick-up paddle 240A, and the returning member 280.

[0085] Further, the processing motor MT12 raises and lowers the pick-up paddle 240A, the trailing end drop member 250A, and the upper discharge roller (nip member) 230A. Therefore, in this embodiment, the processing motor MT12 corresponds to a moving unit that moves the upper discharge roller 230A between the nip position and the separation position (first separation position, second separation position). In addition to the above, this embodiment also includes a return lift motor MT13 for raising and lowering the returning member 280, a discharge roller motor MT14 for driving the lower discharge roller 230B, a pickup motor (sheet pressing motor) MT15 for driving the discharged sheet pickup paddle (sheet pressing (bundle pressing) paddle) 320A, an F-side alignment plate moving motor MT16 for moving (laterally) the front alignment plate 271A in the width direction, an R-side alignment plate moving motor MT17 for moving (laterally) the rear alignment plate 271A in the width direction, an STP moving motor MT18 for moving the staple unit (STP) 400 to change the staple position, an STP motor MT19 for driving the staple unit 400 to staple the sheet bundle, and a loading tray lift motor MT20 for raising and lowering the loading tray 300.

[0086] [Control configuration of sheet processing device] The control configuration of the sheet processing apparatus 200 will be described with reference to Figs. 18 and 19. Fig. 18 is a block diagram showing each motor and each sensor of the sheet processing apparatus 200. Signals from each of these sensors are input to a control unit 203 as a control means, and each motor is controlled by the control unit 203. The control unit 203 is connected to be able to communicate with a control unit of the image forming apparatus 100, and controls the entire sheet processing apparatus 200.

[0087] Such a control unit 203 has a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The CPU controls each unit while reading a program corresponding to a control procedure stored in the ROM. Working data and input data are stored in the RAM, and the CPU performs control by referring to the data stored in the RAM based on the above-mentioned programs, etc.

[0088] Each motor shown in FIG. 18 is as described above. Meanwhile, each sensor will be described with reference to FIG. 2. First, the entrance sensor SN11 is provided on the conveying path 210A and detects the leading edge of the sheet conveyed to the conveying path 210A. The processing upper HP sensor SN12 detects the home positions of the take-in paddle 240A, the trailing end drop member 250A, and the upper discharge roller (nip member) 230A. The return lift HP sensor SN13 detects the home position (position retracted from the processing tray 220) of the return member 280. The processing tray sheet detection sensor SN14 detects the presence or absence of a sheet on the processing tray 220. The paddle HP sensor (sheet pressing HP sensor) SN15 detects the home position of the discharge sheet take-in paddle 320A.

[0089] The F-side alignment plate HP sensor SN16 and the R-side alignment plate HP sensor SN17 respectively detect that the front alignment plate 271A and the rear alignment plate 271A are in positions (home positions) spaced apart in the width direction from the sheets placed on the processing tray 220. The stapler movement HP sensor SN18 detects that the staple unit 400 is in the home position. The sheet detection sensor SN19 detects the top sheet placed on the stacking tray 300. The stacking tray encoder sensor SN20 detects the position of the stacking tray 300 in the lifting / lowering direction. The stacking tray lower limit position detection sensor SN21 detects the lower limit position of the stacking tray 300. The control unit 203 performs various controls, as described below, based on the signals of these sensors.

[0090] Next, the flow of control in each mode of this embodiment will be described with reference to Fig. 19. In this embodiment, there are a straight discharge mode in which a sheet sent to the sheet processing apparatus 200 is discharged directly to the stacking tray 300 without undergoing a predetermined process, a shift mode in which a sheet sent to the sheet processing apparatus 200 is shifted in the width direction (shifted) and discharged to the stacking tray 300 in order to separate the sheets discharged to the stacking tray 300, and a staple mode in which a sheet sent to the sheet processing apparatus 200 is stapled as a predetermined process and discharged to the stacking tray 300. Each of these modes is selected by a user through an operation panel of the image forming apparatus 100 or a PC connected via a network or the like.

[0091] In this embodiment, the mode can be set manually by the user or automatically based on the paper type (sheet length), and in the shift mode, the user can appropriately set which of the two shift discharge processes described below (switchbackless shift discharge process and switchback shift discharge process) to select depending on the final product desired.

[0092] In the staple mode as the binding and discharging process, as shown in Figs. 31(a) to (c), the sheet S (Fig. 31(a)) conveyed downstream in the first conveying direction by the pre-processing rollers 211A and 212A is conveyed in the second conveying direction by the pick-up paddle 240A on the processing tray 220, and the downstream edge (rear end) of the sheet in the second conveying direction is abutted against the rear end regulating member 290, that is, the rear end of the sheet is regulated. Then, the alignment section 270A (a pair of alignment plates 271A) is driven by the F-side alignment plate moving motor MT16 and the R-side alignment plate moving motor MT17, so that the sheet abutted against the rear end regulating member 290 by the alignment section 270A is moved in the sheet width direction and positioned at the binding position. That is, the alignment process is performed. In this embodiment, the sheet is aligned by hitting the sheet from both sides in the sheet width direction using the pair of alignment plates 271A and 271B in the center alignment. By repeating such an operation of restricting the rear end of the sheets and the alignment process, a sheet bundle is formed on the processing tray 220 (FIG. 31(b)). Thereafter, the sheet bundle positioned at the binding position is stapled, and the stapled sheet bundle is discharged onto the stacking tray 300 by the upper discharge rollers 230A and the lower discharge rollers 230B (FIG. 31(c)). In the following shift mode, a shift operation of sheets that are not to be stapled is performed using the pair of alignment plates 271A, 271B and the F-side alignment plate moving motor MT16 and R-side alignment plate moving motor MT17 used in the alignment process when forming the sheet bundle in this staple mode.

[0093] In the shift mode, there are a case where the shift operation is performed on a sheet (first sheet, small size sheet) whose length in the sheet conveying direction (first conveying direction) is a first length, and a case where the shift operation is performed on a sheet (second sheet, large size sheet) whose length in the first conveying direction is a second length longer than the first length. The small size sheet is, for example, a sheet whose length in the first conveying direction is equal to or shorter than a predetermined length, and the large size sheet is, for example, a sheet whose length in the first conveying direction is longer than a predetermined length. The predetermined length is, for example, a so-called A4 vertical size in which an A4 size paper is sent in a vertical direction (the direction in which the longitudinal direction is the conveying direction). In the shift mode, a productivity priority mode that prioritizes productivity and an alignment priority mode that prioritizes sheet alignment can be selected and executed. In any shift mode, the sheet can be shifted in both directions, from the rear side to the front side and from the front side to the rear side (the shift direction is both directions).

[0094] The productivity priority mode as a switchbackless shift discharge process is a mode in which the sheet transported downstream in the first conveying direction by the pre-processing rollers 211A, 212A is not transported in the second conveying direction by the pick-up paddle 240A, but is instead moved (shifted) in the shift direction by the alignment section 270A (a pair of alignment plates 271A) by driving the F-side alignment plate moving motor MT16 and the R-side alignment plate moving motor MT17, and is discharged onto the stacking tray 300 by the upper discharge rollers 230A and the lower discharge rollers 230B.

[0095] The alignment priority mode as a switchback shift discharge process is a mode in which a sheet transported downstream in the first transport direction by pre-processing rollers 211A, 212A is transported in the second transport direction on processing tray 220 by pick-up paddle 240A, and the downstream edge of the sheet in the second transport direction is abutted (regulated) against trailing end regulating member 290, and then, without stapling by staple unit 400, a switchback shift operation is performed in which the sheet is moved (shifted) in the shift direction by alignment section 270A (a pair of alignment plates 271A) by driving F-side alignment plate moving motor MT16 and R-side alignment plate moving motor MT17, and the sheet is discharged onto stacking tray 300 by upper discharge rollers 230A and lower discharge rollers 230B.

[0096] When control is started, the control unit 203 determines whether the discharge mode is the straight discharge mode, the shift mode, or the staple mode (S1). If the straight discharge mode is selected, the sheets sent to the sheet processing device 200 are discharged one by one onto the stacking tray 300 without undergoing any predetermined processing (S2).

[0097] If the shift mode is selected in S1, it is determined whether the sheet size is a large size sheet or a small size sheet (S3). If it is a small size sheet, it is determined whether productivity is prioritized (S4). If productivity is prioritized, the sheet discharged from the conveying path 210A is not conveyed in the second conveying direction by the processing tray 220, but is shifted by the alignment unit 270A and discharged to the stacking tray 300 (S5). If productivity is not prioritized in S4, the sheet discharged from the conveying path 210A is put into the processing tray 220, and is shifted by the alignment unit 270A on the processing tray 220 and discharged to the stacking tray 300 (S6). If the sheet is a large size sheet in S3, the process also proceeds to S6.

[0098] In S1, when the staple mode is selected, the sheet discharged from the conveying path 210A is conveyed in the second conveying direction on the processing tray 220 by the pick-up paddle 240A, and the downstream edge of the sheet in the second conveying direction is abutted against the trailing end regulating member 290. That is, the trailing end of the sheet is regulated. Then, after regulating the trailing end of the sheet, the F-side alignment plate moving motor MT16 and the R-side alignment plate moving motor MT17 are driven to position (align) the sheet at the binding position by the alignment section 270A (a pair of alignment plates 271A). Such operations of regulating the trailing end of the sheet and aligning are repeated to form a sheet bundle on the processing tray 220 (S7). Then, the sheet bundle is stapled (S8). After that, the stapled sheet bundle is discharged to the stacking tray 300 (S9).

[0099] [Switchback-less shift discharge processing (productivity priority mode)] Of the above-mentioned two shift discharge processes, the operation of the sheet processing apparatus 200 in the switchbackless shift discharge process will be described. In the switchbackless shift discharge process of this embodiment, first, the pre-processing rollers 211A and 212A transport a sheet in the first transport direction. Next, in a state where the upper discharge rollers 230A and the lower discharge rollers 230B are in the first separation position, when the downstream end (leading end) in the first transport direction of the sheet transported in the first transport direction by the pre-processing rollers 211A and 212A passes between the upper discharge rollers 230A and the lower discharge rollers 230B (a pair of discharge rotors) and the upstream end (rear end) in the first transport direction of the sheet passes the pre-processing rollers 211A and 212A, the sheet is sandwiched between the pair of alignment plates 271A and 271B without being transported in the second transport direction by the pick-up paddle 240A. In this state, the pair of alignment plates 271A, 271B are moved in a shift direction, which is either one of the two widthwise directions, to perform a shift operation to move the position of the sheet in the shift direction. Next, after this shift operation, the pair of alignment plates 271A, 271B are retracted in the width direction from the sheet that has been shifted, and the upper discharge rollers 230A and the lower discharge rollers 230B are moved to a nip position, and then the sheet is discharged onto the stacking tray 300 by the upper discharge rollers 230A and the lower discharge rollers 230B.

[0100] The switchbackless shift discharge process will be described in more detail with reference to Fig. 20(a) to Fig. 28(b). As shown in Fig. 20(a) and (b), when the sheet S has not yet been conveyed to the conveying path 210A, the upper discharge roller 230A, the pick-up paddle 240A, and the trailing end drop member 250A are each located at their home positions. In particular, the upper discharge roller 230A and the lower discharge roller 230B are located at the first separation position in this state. Also, the pair of alignment plates 271A and 271B are located at their home positions, which are the positions furthest apart from each other.

[0101] 21(a) and 21(b), when the sheet S is conveyed to the entrance of the conveying path 210A, the pair of alignment plates 271A, 271B move closer to each other from the home positions and wait at a receiving position for receiving the sheet S. Even in this state, the upper discharge roller 230A, the pick-up paddle 240A, and the trailing end dropping member 250A are each located at their home positions.

[0102] Next, when the downstream end (leading end) of the sheet S in the first conveying direction passes through the pre-processing nip portion 211a of the pre-processing rollers 211A and 212A while the upper discharge roller 230A and the lower discharge roller 230B are in the first separation position, the upper discharge roller 230A is moved to the second separation position as shown in Figs. 22(a) and 22(b). The relationship between the first separation position and the second separation position is as described in Figs. 4 and 5 above, and the second separation position is a position where the upper discharge roller 230A is further lowered from the first separation position. At this time, the pick-up paddle 240A and the trailing end drop member 250A remain in the home position.

[0103] 23(a) and (b), when the upstream end (rear end) of the sheet S in the first transport direction passes through the pre-processing nip portion 211a of the pre-processing rollers 211A and 212A with the upper discharge roller 230A positioned at the second separation position, the sheet S is sandwiched between the pair of alignment plates 271A and 271B without being picked up by the pick-up paddle 240A and while the sheet S is moving in the first transport direction. That is, the pair of alignment plates 271A and 271B are moved to a widthwise position (clamping position) that matches the size of the sheet S, and the sheet S is sandwiched between the pair of alignment plates 271A and 271B from both sides in the widthwise direction (both sides in the shift direction). The timing at which the pair of alignment plates 271A, 271B start moving may be before or after the trailing end of the sheet S leaves the pre-processing nip portion 211a, as long as the trailing end of the sheet S has left the pre-processing nip portion 211a when the sheet S is clamped between the pair of alignment plates 271A, 271B.

[0104] In the present embodiment, the moving speed of the pair of alignment plates 271A, 271B can be changed. Specifically, by changing the drive speed of the F-side alignment plate moving motor MT16 and the R-side alignment plate moving motor MT17, the moving speed of the pair of alignment plates 271A, 271B is changed between when the pair of alignment plates 271A, 271B move to sandwich the sheet and when the pair of alignment plates 271A, 271B shift the sheet in the switchbackless shift discharge process. In this embodiment, when the sheet S, whose trailing edge has passed through the pre-processing nip portion 211a, is not transported in the second transport direction by the pick-up paddle 240A and the sheet S is moving in the first transport direction, the moving speed at which the F-side alignment plate moving motor MT16 and the R-side alignment plate moving motor MT17 move the pair of alignment plates 271A and 271B from the receiving position to the clamping position at which the sheet is clamped is set slower than the moving speed at which the F-side alignment plate moving motor MT16 and the R-side alignment plate moving motor MT17 move the pair of alignment plates 271A and 271B when performing a shift operation. For example, the moving speed at which the sheet S is clamped by the pair of alignment plates 271A and 271B is 261 mm / sec, and the moving speed at the time of the shift operation is 313 mm / sec.

[0105] This is because if the movement speed when the sheet S is sandwiched between the pair of alignment plates 271A, 271B is fast, the pair of alignment plates 271A, 271B may strongly abut against the edge of the sheet S, which may cause skew in the sheet S. On the other hand, during the shift operation, the movement speed of the pair of alignment plates 271A, 271B is increased to improve productivity. Note that the movement speed of the pair of alignment plates 271A, 271B during the shift operation may be the same as the movement speed when the sheet S is sandwiched between the pair of alignment plates 271A, 271B.

[0106] In addition, when the sheet S is sandwiched between the pair of alignment plates 271A and 271B, the movement speed of the front-side alignment plate 271A and the movement speed of the rear-side alignment plate 271B are set to be the same. After the sheet S is sandwiched between the pair of alignment plates 271A and 271B, the pair of alignment plates 271A and 271B are simultaneously moved in the shift direction to perform the shift operation. However, in this embodiment, the movement start timing of the alignment plates 271A and 271B when the sheet S is sandwiched between the pair of alignment plates 271A and 271B is shifted. Specifically, when the sheet is shifted to the front side, the rear-side alignment plate 271B is moved first, and then the front-side alignment plate 271A is moved.

[0107] As described above, in this embodiment, the front alignment plate 271A is biased toward the rear side by the biasing spring 2714 (see FIG. 7 to FIG. 8(b)). Therefore, by moving the rear alignment plate 271B first as described above, the rear alignment plate 271B without the biasing spring hits the sheet first, and then the front alignment plate 271A with the biasing spring 2714 hits the sheet. This allows the biasing spring 2714 to efficiently absorb the force when the sheet is sandwiched between the pair of alignment plates 271A and 271B, and improves the alignment of the sheet. If the front alignment plate 271A with the biasing spring hits the sheet first, the sheet may be blown to the rear side by the biasing force of the biasing spring 2714, causing the alignment of the sheet to be disturbed. For this reason, in this embodiment, the alignment plate without the biasing spring is moved first so that it hits the sheet first.

[0108] Here, in the case of this embodiment, the pair of alignment plates 271A, 271B are located 10 mm from both ends of the sheet at the receiving position. When the pair of alignment plates 271A, 271B are moved toward the clamping position to sandwich the sheet, the rear side alignment plate 271B is moved 10 mm toward the front side, and the front side alignment plate 271A is moved 10.5 mm toward the rear side. When the pair of alignment plates 271A, 271B sandwich the sheet, the front side alignment plate 271A pushes the sheet toward the rear side to align the sheet. At this time, the biasing spring 2714 absorbs the reaction force from the sheet when the front side alignment plate 271A pushes the sheet, so that the sheet can be prevented from bending. The front side alignment plate 271A moves 10.5 mm toward the rear side to push the sheet, and then returns 0.5 mm to the front side. As a result, the pair of alignment plates 271A, 271B are positioned at the clamping position in a state where the sheet is sandwiched and aligned.

[0109] In this embodiment, the amount of movement when the sheet is sandwiched between the pair of alignment plates 271A and 271B is different between the side with the biasing spring and the side without the biasing spring, but it may be the same. That is, the amount of movement on the front side may be the same as the amount of movement on the rear side.

[0110] A biasing spring may be provided on the rear alignment plate, and the front alignment plate without the biasing spring may be abutted against the sheet first. In the switchback shift discharge process, the sheet is shifted on the processing tray 220, and the sheet is sandwiched between the pair of alignment plates 271A and 271B in order to perform the shifting operation in the same manner as described above. In both the switchbackless shift discharge process and the switchback shift discharge process, when the sheet is sandwiched between the pair of alignment plates 271A and 271B, the pair of alignment plates 271A and 271B may be moved substantially simultaneously to abut against the sheet substantially simultaneously. Even in this case, the sheet is less likely to be disturbed during alignment than when the alignment plate with the biasing spring hits the sheet first.

[0111] After the sheet S is sandwiched between the pair of alignment plates 271A and 271B as described above, the sheet S is moved in the shift direction while being sandwiched between the pair of alignment plates 271A and 271B as shown in FIGS. 24(a) and (b). That is, a shift operation is performed. After the shift operation is completed, the upper discharge roller 230A is lowered to the nip position as shown in FIGS. 25(a) and (b), and the sheet S is nipped between the upper discharge roller 230A and the lower discharge roller 230B. After the sheet S is nipped between the upper discharge roller 230A and the lower discharge roller 230B, the pair of alignment plates 271A and 271B are moved from the sheet S to the first retracted position as shown in FIGS. 26(a) and (b). In this example, the shift direction is from the rear side to the front side, so of the pair of alignment plates 271A, 271B, the front alignment plate 271A is one alignment plate and the rear alignment plate 271B is the other alignment plate.

[0112] 27(a) and (b), the lower discharge roller 230B is rotated to discharge the sheet S nipped by the upper discharge roller 230A and the lower discharge roller 230B onto the stacking tray 300. At this time, after the shift operation by the pair of alignment plates 271A, 271B, the sheet S that has been shifted is transported in the first transport direction by the upper discharge roller 230A and the lower discharge roller 230B in a state in which the pair of alignment plates 271A, 271B are moved from the clamping position to the first retracted position from the sheet that has been shifted.

[0113] Next, before the upstream end (rear end) in the first conveying direction of the sheet conveyed by the upper discharge roller 230A and the lower discharge roller 230B passes through the discharge nip portion 230a formed by the upper discharge roller 230A and the lower discharge roller 230B at the nip position, the pair of alignment plates 271A, 271B are moved from the first retracted position to the second retracted position. Then, with the pair of alignment plates 271A, 271B in the second retracted position, the sheet is discharged onto the stacking tray 300 by the upper discharge roller 230A and the lower discharge roller 230B.

[0114] That is, in this embodiment, while the sheet S is nipped and conveyed by the upper discharge roller 230A and the lower discharge roller 230B, the pair of alignment plates 271A, 271B are positioned at a first retracted position that is closer to the sheet than the second retracted position. This suppresses skew when the sheet S is discharged. Then, before the trailing end of the sheet S passes through the discharge nip portion 230a, the pair of alignment plates 271A, 271B are moved to the second retracted position. This suppresses contact between the pair of alignment plates 271A, 271B and the sheet S when it is not nipped by the upper discharge roller 230A and the lower discharge roller 230B after the trailing end of the sheet S leaves the discharge nip portion 230a.

[0115] In the present embodiment, as described above, the pair of alignment plates 271A, 271B are disposed so as to straddle the upper discharge roller 230A and the lower discharge roller 230B in the first transport direction, and a part of the pair of alignment plates 271A, 271B including the downstream end in the first transport direction is located downstream of the discharge nip portion 230a in the first transport direction. Therefore, if the pair of alignment plates 271A, 271B are positioned at the first retracted position even after the rear end of the sheet S has passed through the discharge nip portion 230a, there is a risk that the sheet S will come into contact with the downstream portion of the pair of alignment plates 271A, 271B from the discharge nip portion 230a.

[0116] If the sheet S comes into contact with the pair of alignment plates 271A, 271B while not being conveyed by the upper discharge rollers 230A and the lower discharge rollers 230B, this creates resistance when the sheet S is discharged, and there is a risk that the stackability of the sheet S may be reduced, for example, the rear end of the sheet S may lean against the standing surface 310a when stacked on the stacking tray 300. For this reason, in this embodiment, the pair of alignment plates 271A, 271B are moved to the second retracted position before the rear end of the sheet S passes through the discharge nip portion 230a, so that the sheet S not being nipped by the upper discharge rollers 230A and the lower discharge rollers 230B is less likely to come into contact with the pair of alignment plates 271A, 271B.

[0117] On the other hand, if the pair of alignment plates 271A, 271B are positioned at the second retracted position from the start of the discharge operation of the sheet S, there is a risk that the sheet S may become skewed while the sheet S is being transported by the upper discharge rollers 230A and the lower discharge rollers 230B. For this reason, in this embodiment, while the sheet S is being transported by the upper discharge rollers 230A and the lower discharge rollers 230B, the pair of alignment plates 271A, 271B are positioned at the first retracted position as much as possible to suppress skew of the sheet S. Then, by moving the pair of alignment plates 271A, 271B to the second retracted position before the rear end of the sheet S passes through the discharge nip portion 230a, a decrease in the loading capacity of the stacking tray 300 for the sheet S is suppressed.

[0118] In this embodiment, the timing at which the pair of alignment plates 271A, 271B start moving to the first evacuation position after the shift operation is after the sheet S is nipped by the upper discharge roller 230A and the lower discharge roller 230B. The timing at which the pair of alignment plates 271A, 271B start moving from the first evacuation position to the second evacuation position is when the rear end of the sheet S is located, for example, 10 mm before (upstream in the first transport direction) the discharge nip point (the central position in the first transport direction of the discharge nip portion 230a).

[0119] That is, in this embodiment, in a state where the pair of alignment plates 271A, 271B are in the first retracted position, the upper discharge roller 230A and the lower discharge roller 230B nip the sheet S and transport it by a predetermined amount (until the rear end of the sheet S is located 10 mm before the discharge nip point), and then the pair of alignment plates 271A, 271B are moved to the second retracted position to discharge the sheet S onto the stacking tray 300. Note that in this embodiment, the speed at which the sheet S is transported by the upper discharge roller 230A and the lower discharge roller 230B (discharge speed) is decelerated at the timing when the pair of alignment plates 271A, 271B start moving from the first retracted position to the second retracted position. This prevents the position of the discharged sheet S from being disturbed on the stacking tray 300 while suppressing a decrease in productivity.

[0120] The above-mentioned "position where the rear end of the sheet S is 10 mm before the discharge nip point" may be slightly earlier or later. Also, the timing of moving the pair of alignment plates 271A, 271B from the first retracted position to the second retracted position and the timing of slowing down the discharge speed may be shifted. Also, a configuration may be adopted in which the discharge speed is not slowed down.

[0121] 28(a) and 28(b), after the sheet S is discharged onto the stacking tray 300, the sheet S is picked up by the discharged sheet pick-up paddle 320A and further holds down the rear end of the sheet S. At this time, the pair of alignment plates 271A, 271B move from the second retracted position to the receiving position to receive the next sheet.

[0122] In the case of such a switchback-less shift discharge process (productivity priority mode), since there is no operation (switchback transport) of transporting the sheet S in the second transport direction on the processing tray 220, the shift operation of the sheet S can be performed faster than when it is performed on the processing tray 220. Note that the productivity priority mode is preferably applicable to small size sheets, but may also be performed on large size sheets. In other words, it may be performed on all sheets that are shifted and discharged without being stapled.

[0123] In particular, in the switchbackless shift discharge process, in the present embodiment, the sheet conveyed by the pre-processing rollers 211A and 212A is sandwiched between the pair of alignment plates 271A and 271B without being nipped by the upper discharge roller 230A and the lower discharge roller 230B, and the sheet is shifted as it is. This makes it possible to further increase the speed of the switchbackless shift discharge process. That is, as in the configuration described in Patent Document 1, the sheet conveyed by the pre-processing rollers 211A and 212A is nipped by the upper discharge roller 230A and the lower discharge roller 230B, and the nip is released, and then the sheet is sandwiched between the pair of alignment plates 271A and 271B to perform the shift operation. In contrast, in the present embodiment, there is no operation of nipping the sheet by the upper discharge roller 230A and the lower discharge roller 230B, and no operation of releasing the nip, so that the switchbackless shift discharge process can be further increased in speed, and productivity can be improved.

[0124] [Formation of sheet stacks by shift discharge processing] Here, in this embodiment, a process of shifting sheets one by one in the shift direction, discharging them onto the stacking tray 300 without binding them, and forming a sheet bundle consisting of a plurality of unstitched sheets will be described. For example, as shown in FIG. 32, there is a case where a plurality of unstitched sheet bundles are shifted in the shift direction and discharged onto the stacking tray 300 (this is called a sorting and discharging process). This sorting and discharging process is the following process. First, after a sheet is conveyed in the first conveying direction by the pre-processing rollers 211A and 212A, the sheet conveyed by the pre-processing rollers 211A and 212A is not conveyed in the second conveying direction by the pick-up paddle 240A, and in a state where the sheet S is moving in the first conveying direction, the pair of alignment plates 271A and 271B are driven by the front side (F side) alignment plate moving motor MT16 and the rear side (R side) alignment plate moving motor MT17 to sandwich the sheet between the pair of alignment plates 271A and 271B and move the sheet in the shift direction. Next, the sheets moved in the shift direction by the pair of alignment plates 271A and 271B are discharged one by one to the shift position on the stacking tray 300 by the upper discharge rollers 230A and the lower discharge rollers 230B multiple times, and the first unbound sheet bundle is stacked. Next, the sheets transported by the pre-processing rollers 211A and 212A are discharged one by one to a position shifted upstream in the shift direction from the shift position on the stacking tray 300 by the upper discharge rollers 230A and the lower discharge rollers 230B without being transported in the second transport direction by the pick-up paddle 240A, and the second unbound sheet bundle is stacked. Note that "stacking a sheet bundle" here means forming a sheet bundle on the stacking tray 300, and even if there is only one sheet bundle as in this embodiment, discharging multiple sheets one by one to the stacking tray 300 to form a sheet bundle on the stacking tray 300 is called "stacking a sheet bundle".

[0125] In the sorting and discharging process, the second sheet bundle may be stacked by discharging the sheets one by one onto the stacking tray 300 by moving them in the direction opposite to the shift direction of the first sheet bundle by the pair of alignment plates 271A, or may be stacked by discharging the sheets one by one onto the stacking tray 300 in the position in the shift direction conveyed by the pre-processing rollers 211A and 212A without moving them in the direction opposite to the shift direction of the first sheet bundle (same as the straight discharging mode). In short, as shown in FIG. 32, it is sufficient that the first sheet bundle and the second sheet bundle are stacked with a shift in the shift direction. Also, before the first sheet bundle, a sheet bundle may be stacked on the stacking tray 300 in the position in the shift direction conveyed by the pre-processing rollers 211A and 212A without moving them in the direction opposite to the shift direction of the first sheet bundle, and then the first sheet bundle may be moved in the shift direction to be stacked on the stacking tray 300.

[0126] When stacking the second sheet bundle on the stacking tray 300, if the sheets are discharged onto the stacking tray 300 at the same position in the shift direction conveyed by the pre-processing rollers 211A and 212A without moving in the opposite direction to the shift direction of the first sheet bundle, the sheets may be discharged after only width alignment by the pair of alignment plates 271A before being discharged by the upper discharge rollers 230A and the lower discharge rollers 230B. This improves the alignment of the second sheet bundle on the stacking tray 300. Also, even in the case of only the straight discharge mode, the sheets may be width aligned one by one by the pair of alignment plates 271A before being discharged onto the stacking tray 300.

[0127] Such a sorting and discharging process includes a sorting process and a grouping process. For example, when discharging 10 sets of sheets each consisting of 5 sheets, the sorting process is a process of shifting the sheet bundle one by one and stacking them on the stacking tray 300. The grouping process is a process of shifting the 10 sheets of the first page, the 10 sheets of the second page, the 10 sheets of the fifth page, and stacking them on the stacking tray 300. The sorting process and the grouping process can be selected by the user, for example, through an operation panel of the image forming apparatus 100 or an external terminal such as a PC (personal computer) connected via a network or the like. Then, a command for the process selected by the user is sent from the image forming apparatus 100 to the sheet processing apparatus 200A, and the sheet processing apparatus 200A executes the process.

[0128] The sorting and discharging process also includes a process of shifting the sheet bundle for each job and stacking it on the stacking tray 300 when jobs with different contents are successively input to the image forming system 1000A. For example, consider a case where a person A inputs a job to form a bundle of 10 sheets as a first job, and then a person B inputs a job to form a bundle of 5 sheets as a second job. In this case, the sheet bundle in the first job is shifted in the shift direction and stacked on the stacking tray 300, and then the sheet bundle in the second job is stacked on the stacking tray 300 without shifting or by moving it in the opposite direction to the shift direction.

[0129] In addition, in this embodiment, as a process of shifting and discharging sheets without binding them, the above-mentioned switchback shift discharge process (alignment priority mode) and sorting discharge process can be executed. The sorting discharge process includes the above-mentioned switchbackless shift discharge process (productivity priority mode).

[0130] In the switchbackless shift discharge process, the sheets are shifted one by one and discharged onto the stacking tray 300. In this case, if the sheets shifted onto the stacking tray 300 are simply stacked to form a sheet bundle, the alignment of the sheets on the stacking tray 300 may be deteriorated. In addition, even if the sheet bundle is formed on the stacking tray 300 and then the discharged sheet pick-up paddle 320A is used to pick up the sheets, only the top sheet of the sheet bundle is picked up, and conversely, the alignment of the sheets may be deteriorated. Therefore, in this embodiment, as described above with reference to FIGS. 28(a) and 28(b), after the sheets are discharged onto the stacking tray 300, the sheets are picked up by the discharged sheet pick-up paddle 320A.

[0131] That is, when forming a sheet stack shifted onto the stacking tray 300 (on the stacking section) without performing a binding process, the shift discharge process and the scraping process are repeatedly performed on a plurality of sheets to form a sheet stack consisting of a plurality of sheets on the stacking tray 300. The shift discharge process is a process in which a sheet is shifted by the alignment section 270A, and the sheet shifted by the alignment section 270A is discharged onto the stacking tray 300 by the upper discharge rollers 230A and the lower discharge rollers 230B, and is the above-mentioned switchback-less shift discharge process. The scraping process is a process in which the sheet discharged onto the stacking tray 300 is conveyed in the third conveying direction by the discharge sheet scraping paddle 320A.

[0132] Furthermore, when the shift discharge process and the take-in process are repeated, the take-in paddle 320A stops at a position on the stacking tray 300 where it presses the upper surface of the sheet it has taken in until the next sheet is discharged (until the trailing edge of the sheet passes the nip point between the upper discharge rollers 230A and the lower discharge rollers 230B). Then, when the next sheet is discharged onto the stacking tray 300, the take-in paddle 320A rotates to take in the sheet and further presses the trailing edge of the sheet. This makes it possible to prevent the sheet already taken in on the stacking tray 300 from being shifted by the next sheet.

[0133] This improves the alignment of the sheet stack when forming an unstitched sheet stack moved in the shift direction on the stacking tray 300. That is, the sheet is shifted and discharged onto the stacking tray 300, and then the discharged sheet is picked up by the discharged sheet pick-up paddle 320A, so that the sheet discharged onto the stacking tray 300 can be abutted against the standing surface 310a provided at the upstream end of the stacking tray 300 in the first conveying direction. This operation is then repeated for each sheet, so that the alignment of the sheet stack discharged onto the stacking tray 300 can be improved.

[0134] This operation can also be performed in the switchback shift discharge process. That is, when the switchback shift discharge process is performed, a sheet bundle is usually formed on the processing tray 220 and then discharged onto the stacking tray 300. However, the sheets may be shifted one by one on the processing tray 220 and discharged onto the stacking tray 300. Even in this case, by performing a scraping process on each sheet discharged onto the stacking tray 300, the alignment of the sheet bundle discharged onto the stacking tray 300 can be improved.

[0135] Furthermore, even when a second sheet stack is formed on the stacking tray 300 or in the straight discharge mode, the above-mentioned scraping process is performed on the sheets discharged one by one onto the stacking tray 300, thereby improving the alignment of the second sheet stack or the sheet stack formed by being discharged in the straight discharge mode.

[0136] <Second embodiment> The second embodiment will be described with reference to FIG. 29. In the first embodiment described above, in the switchbackless shift discharge process, when the leading edge of the sheet passes between the upper discharge roller 230A and the lower discharge roller 230B, the upper discharge roller 230A is moved to the second separation position (see FIG. 22(b)). In contrast, in this embodiment, when the trailing edge of the sheet passes through the pre-processing nip portion 211a, the trailing edge dropping member 250A is moved from the upper position to the lower position. Since the other configurations and functions are the same as those of the first embodiment described above, the same reference numerals are used for the similar configurations, and the description and illustration are omitted or simplified, and the following description will focus on the points different from the first embodiment.

[0137] In this embodiment, when the switchbackless shift discharge process is performed, the sheet S is conveyed toward the pre-processing rollers 211A and 211B via the conveying path 210A in the same manner as in the case shown in Fig. 20(a) to Fig. 21(b). Then, as shown in Fig. 29, when the leading edge of the sheet S conveyed in the first conveying direction by the pre-processing rollers 211A and 211B passes between the upper discharge roller 230A and the lower discharge roller 230B and the trailing edge of the sheet S passes the pre-processing rollers 211A and 211B, the trailing edge dropping member 250A is moved from the upper position to the lower position. As a result, the sheet S is dropped onto the processing tray 220, and both widthwise edges of the sheet S face the pair of alignment plates 271A and 271B over a wide range in the first conveying direction.

[0138] In this state, the sheet S is not transported in the second transport direction by the pick-up paddle 240A, but is sandwiched between the pair of alignment plates 271A, 271B and shifted as in the first embodiment shown in FIG. 23(a) and subsequent figures, and the sheet S is discharged. By dropping the sheet S onto the processing tray 220 by the trailing end dropping member 250A in this manner, the sheet S can be more reliably sandwiched between the pair of alignment plates 271A, 271B. This improves the alignment of the sheet.

[0139] In this embodiment, as shown in FIG. 29, when the trailing end dropping member 250A is moved to the lower position, the pick-up paddle 240A also moves from the upper retracted position to the return position. This is because the configurations of the various parts are linked by the above-mentioned cam mechanism 613. In this embodiment, as described in FIG. 16, the pick-up paddle 240A can rise independently by the gap between the second protrusion 2405 when the pick-up paddle 240A is in the return position and the part of the engagement recess 2502 located above the second protrusion 2405. Therefore, after the sheet S is dropped by the trailing end dropping member 250A, the pick-up paddle 240A is raised from the return position by the above-mentioned gap to separate the pick-up paddle 240A from the sheet S. This prevents the pick-up paddle 240A from interfering with the sheet shifting operation by the pair of alignment plates 271A and 271B.

[0140] Also, the trailing end dropping member 250A may be returned to the upper position immediately after dropping the sheet S onto the processing tray 220. For example, the trailing end dropping member 250A may start moving to the upper position before the pair of alignment plates 271A, 271B sandwich the sheet S, or the trailing end dropping member 250A may start moving before the shift operation. Furthermore, the trailing end dropping member 250A may be configured not to be linked to the pick-up paddle 240A, for example, by being driven separately from the pick-up paddle 240A.

[0141] <Third embodiment> The third embodiment will be described with reference to Figs. 30(a) and 30(b). In the first embodiment described above, when the leading edge of the sheet S conveyed in the first conveying direction by the pre-processing rollers 211A and 211B passes between the upper discharge roller 230A and the lower discharge roller 230B and the trailing edge of the sheet S passes through the pre-processing rollers 211A and 211B, the sheet S is sandwiched between the pair of alignment plates 271A and 271B and then shifted (see Figs. 23(a) to 24(b)). In contrast, in this embodiment, the sheet is not sandwiched between the pair of alignment plates 271A and 271B, and one of the alignment plates is moved in the shift direction while the sheet is moving in the first conveying direction to perform the shift operation. Since the other configurations and functions are the same as those of the first embodiment described above, the same reference numerals are attached to the similar configurations and explanations and illustrations are omitted or simplified, and the following description will focus on the points different from the first embodiment.

[0142] In the first embodiment described above, a configuration has been described in which the switchback-less shift discharge process is executed for small-size sheets and the switchback-less shift discharge process is executed for large-size sheets in the shift mode. In this embodiment, in the switchback-less shift discharge process for small-size sheets, two types of switchback-less shift discharge processes can be executed according to the size of the sheet.

[0143] That is, in this embodiment, as two types of switchbackless shift discharge processes, a first shift discharge process and a second shift discharge process can be executed. The first shift discharge process is executed when the sheet conveyed by the pre-processing rollers 211A, 212A is a first size, and the second shift discharge process is executed for a sheet of a second size whose length in the first conveying direction of the sheet conveyed by the pre-processing rollers 211A, 212A is shorter than that of the sheet of the first size. The first shift discharge process is the switchbackless shift discharge process described in the first or second embodiment. Also, the second shift discharge process may be executed in the sorting discharge process described in FIG. 32.

[0144] On the other hand, in the second shift discharge process, after the operations of Fig. 22(a) and (b) of the first embodiment, the operation shown in Fig. 30 is performed without performing the operations of Fig. 23(a) and (b). That is, when the leading edge of the sheet S conveyed in the first conveying direction by the pre-processing rollers 211A and 212A passes between the upper discharge roller 230A and the lower discharge roller 230B and the trailing edge of the sheet S passes the pre-processing rollers 211A and 212A, the sheet S is not conveyed in the second conveying direction by the pick-up paddle 240A, and while the sheet S is moving in the first conveying direction, a shift operation is performed to move the position of the sheet S in the shift direction by moving one of the pair of alignment plates 271A and 271B on one side in the width direction in a shift direction (predetermined shift direction) toward the other side in the width direction. In this embodiment, since the shift direction is toward the front side, the alignment plate on one side is the rear alignment plate 271B, and the alignment plate on the other side is the front alignment plate 271A.

[0145] Here, the second size sheet for which the second shift discharge process is performed is, for example, a sheet of B5 size or a size smaller than B5, and is a sheet such that the center of gravity G of the sheet S is located within the range of the alignment plate 271A when the alignment plate 271B on one side abuts against the end of the sheet S in the width direction, as shown in Fig. 30. As long as the second size sheet satisfies this requirement, it differs depending on the configuration and size of the sheet processing device, and is not limited to a sheet of B5 size or smaller.

[0146] In this way, when one side of the alignment plate 271A abuts against the widthwise end of the sheet S, that is, when the leading edge of the sheet S passes between the upper discharge roller 230A and the lower discharge roller 230B and the trailing edge of the sheet S passes through the pre-processing rollers 211A, 212A, the center of gravity G of the sheet S overlaps with the alignment plate 271A when viewed from the width direction, a shift operation is possible by directly abutting the sheet with one side of the alignment plate 271A without clamping the sheet between the pair of alignment plates 271A, 271B.

[0147] If the second shift discharge process is performed on a sheet whose center of gravity G is not within the range of the alignment plate 271A in the above state, for example, a sheet whose center of gravity G is located further downstream than the downstream end of the alignment plate 271A in the first conveying direction, the sheet may be tilted when the alignment plate 271A hits the sheet. For this reason, the switchbackless shift discharge process (i.e., the first shift discharge process) described in the first and second embodiments is performed on such a sheet.

[0148] After the shift operation by the one-side alignment plate 271A, the one-side alignment plate 271A is retracted in the width direction from the sheet S that has been shifted, and the upper discharge roller 230A and the lower discharge roller 230B are moved to the nip position. Then, the sheet is discharged onto the stacking tray 300 by the upper discharge roller 230A and the lower discharge roller 230B.

[0149] In this embodiment, the sheet is not sandwiched between the pair of alignment plates 271A, 271B, and the shift operation is performed by moving one of the alignment plates in the shift direction, so that the switchbackless shift discharge process can be further accelerated and productivity can be improved.

[0150] <Other embodiments> In each of the above-described embodiments, the sheet processing device 200 is arranged in the internal space 130 of the image forming apparatus 100, but the sheet processing device of the present invention may be, for example, attached to the side of the image forming apparatus. Also, the sheet processing device may be controlled by a control unit provided in the image forming apparatus.

[0151] The disclosure of this embodiment also includes the following configuration. (Configuration 1) a first conveying unit that conveys the sheet in a first conveying direction; a placement section for placing the sheet conveyed by the first conveying section; an abutting portion against which an upstream edge of the sheet on the placement portion in the first transport direction is abutted; a second conveying section that conveys the sheet in a second conveying direction in which an upstream edge of the sheet on the placement section in the first conveying direction faces the abutting section; a pair of alignment plates arranged on both sides of the sheet abutted against the abutting portion with respect to a width direction of the sheet intersecting the first conveying direction, and aligning the sheet abutted against the abutting portion in the width direction; a drive unit that moves the pair of alignment plates in the width direction; a processing section that performs a binding process on a sheet bundle including a plurality of sheets that have been aligned in the width direction by the pair of alignment plates; a stacking section that is disposed downstream of the placement section in the first transport direction and stacks the sheets transported in the first transport direction by the first transport section; a pair of discharge rotors configured to discharge the sheet conveyed in the first conveying direction by the first conveying unit to the stacking unit; a moving unit that moves a position of at least one of the pair of discharge rotors to a nip position where the pair of discharge rotors nip a sheet and a separated position where the pair of discharge rotors are separated from each other, a binding discharge process in which, after the first conveying unit conveys a sheet in the first conveying direction, the sheet conveyed by the first conveying unit is conveyed in the second conveying direction on the placement unit by the second conveying unit, a downstream end edge of the sheet in the second conveying direction is abutted against the abutment unit, and the sheet is aligned at the binding position by the pair of alignment plates, and the process is repeated to perform the binding process on the multiple sheets positioned at the binding position by the processing unit, and the multiple sheets that have been subjected to the binding process are discharged to the stacking unit by the pair of discharge rotating bodies; a sheet is conveyed in the first conveying direction by the first conveying unit, and in a state in which the pair of discharge rotating bodies are at the separated position, a downstream end of the sheet conveyed in the first conveying direction by the first conveying unit passes between the pair of discharge rotating bodies and an upstream end of the sheet conveyed in the first conveying direction by the first conveying unit passes through the first conveying unit, and then, without conveying the sheet whose upstream end in the first conveying direction has passed the first conveying unit in the second conveying direction by the second conveying unit, the sheet is sandwiched between the pair of alignment plates while the sheet is moving in the first conveying direction, and in this state, the pair of alignment plates are moved in a shift direction which is one of both sides in the width direction, so that the upstream end of the first conveying direction is a sorting and discharging process including: performing a shift operation to move a position of a sheet that has passed through the first conveying unit in the shift direction; after the shift operation by the pair of alignment plates, retracting the pair of alignment plates in the width direction from the sheet that has been shifted by the shift operation and moving the pair of discharge rotors to the nip position; and then discharging the sheets one by one to the shift position on the stacking unit by the pair of discharge rotors, thereby repeating this process multiple times to stack an unbound first sheet stack; and discharging the sheets transported by the first conveying unit one by one to a position shifted upstream of the shift position on the stacking unit in the shift direction by the pair of discharge rotors, without transporting the sheets in the second conveying direction by the second conveying unit, thereby repeating this process multiple times to stack an unbound second sheet stack. A sheet processing apparatus capable of performing the above. (Configuration 2) the moving unit is capable of moving a position of at least one of the pair of discharge rotors between a first separation position where the pair of discharge rotors are spaced apart from the nip position and a second separation position where the pair of discharge rotors are spaced apart from the nip position and the distance between the pair of discharge rotors is narrower than the first separation position, In the sorting and discharging process, when the downstream end in the first conveying direction of the sheet conveyed in the first conveying direction by the first conveying unit passes between the pair of discharge rotors while the pair of discharge rotors is in the first separation position, the pair of discharge rotors are moved to the second separation position, and the sheet whose upstream end in the first conveying direction has passed the first conveying unit is not conveyed in the second conveying direction by the second conveying unit, and while the sheet is moving in the first conveying direction, the sheet processing device described in configuration 1 performs the shift operation by clamping the sheet between the pair of alignment plates. (Configuration 3) a rotating shaft is provided between a nip portion where the pair of discharge rotating bodies nip the sheet at the nip position and an upstream end of the stacking portion in the first transport direction, and a pick-up portion is further provided which rotates in contact with an upper surface of the sheet discharged to the stacking portion to transport the sheet discharged to the stacking portion in a second transport direction opposite to the first transport direction, When the shift operation is performed to form a sheet stack on the stacking section without processing by the processing section, the sheet processing apparatus according to configuration 1 or 2 repeatedly performs the following steps on a plurality of sheets during the sorting and discharging process: a process from the first conveying section conveying the sheets in the first conveying direction to the shift operation; and a pick-up process in which the pick-up section conveys the sheets discharged to the stacking section by the pair of discharge rotating bodies after the shift operation in the second conveying direction. This forms a sheet stack consisting of the plurality of sheets on the stacking section. (Configuration 4) A sheet processing device as described in any one of configurations 1 to 3, wherein the speed at which the drive unit moves the pair of alignment plates when clamping a sheet whose upstream end in the first conveying direction has passed the first conveying section without the sheet being conveyed in the second conveying direction by the second conveying section and the sheet is moving in the first conveying direction is slower than the speed at which the drive unit moves the pair of alignment plates when performing the shift operation. (Configuration 5) The alignment plate further includes a biasing portion that biases one of the pair of alignment plates toward the other alignment plate, A sheet processing device described in any one of configurations 1 to 4, wherein the drive unit moves the pair of alignment plates so that, during the sorting and discharging process, when the upstream end in the first conveying direction of the sheet that has passed through the first conveying unit is clamped between the pair of alignment plates, one alignment plate abuts against the sheet after the other alignment plate abuts against the sheet. (Configuration 6) 6. The sheet processing apparatus according to any one of configurations 1 to 5, wherein the pair of alignment plates are disposed so as to straddle the pair of discharge rotors in the first transport direction. (Configuration 7) The sheet processing apparatus of configuration 6, in which, in the sorting and discharging process, after the shifting operation by the pair of alignment plates, the pair of alignment plates are retracted to a first retract position away from the sheet that has been shifted, and the sheet is transported in the first conveying direction by the pair of discharge rotors, and before the upstream end in the first conveying direction of the sheet transported by the pair of discharge rotors passes through the discharge nip portion formed by the pair of discharge rotors at the nip position, the pair of alignment plates are retracted to a second retract position further away from the sheet than the first retract position, and the sheet is discharged to the stacking portion by the pair of discharge rotors while the pair of alignment plates are in the second retract position. (Configuration 8) a sheet dropper that moves from a position above a position below a sheet transported in the first transport direction by the first transport unit in a vertical direction to a position below the sheet transported in the first transport direction by the first transport unit, and drops an upstream end of the sheet in the first transport direction, the upstream end being transported in the first transport direction by the first transport unit, toward the placement unit, In the sorting and discharging process, when the downstream end in the first conveying direction of the sheet transported in the first conveying direction by the first conveying passes between the pair of discharge rotating bodies and the upstream end in the first conveying direction of the sheet transported in the first conveying direction by the first conveying section passes through the first conveying section, the sheet drop section is moved from the upper position to the lower position, and the sheet whose upstream end in the first conveying direction has passed through the first conveying section is clamped between the pair of alignment plates and the shift operation is performed without being transported in the second conveying direction by the second conveying section. (Configuration 9) a first conveying unit that conveys the sheet in a first conveying direction; a placement section for placing the sheet conveyed by the first conveying section; an abutting portion against which an upstream edge of the sheet on the placement portion in the first transport direction is abutted; a second conveying section that conveys the sheet in a second conveying direction in which an upstream edge of the sheet on the placement section in the first conveying direction faces the abutting section; a pair of alignment plates arranged on both sides of the sheet abutted against the abutting portion with respect to a width direction of the sheet intersecting the first conveying direction, and aligning the sheet abutted against the abutting portion in the width direction; a drive unit that moves the pair of alignment plates in the width direction; a processing section that performs a binding process on a sheet bundle including a plurality of sheets that have been aligned in the width direction by the pair of alignment plates; a stacking section that is disposed downstream of the placement section in the first transport direction and stacks the sheets transported in the first transport direction by the first transport section; a pair of discharge rotors configured to discharge the sheet conveyed in the first conveying direction by the first conveying unit to the stacking unit; a moving unit that moves a position of at least one of the pair of discharge rotors to a nip position where the pair of discharge rotors nip a sheet and a separated position where the pair of discharge rotors are separated from each other, a binding discharge process in which, after the first conveying unit conveys a sheet in the first conveying direction, the sheet conveyed by the first conveying unit is conveyed in the second conveying direction on the placement unit by the second conveying unit, a downstream end edge of the sheet in the second conveying direction is abutted against the abutment unit, and the sheet is aligned at the binding position by the pair of alignment plates, and the process is repeated to perform the binding process on the multiple sheets positioned at the binding position by the processing unit, and the multiple sheets that have been subjected to the binding process are discharged to the stacking unit by the pair of discharge rotating bodies; a sheet is conveyed in the first conveying direction by the first conveying unit, and in a state in which the pair of discharge rotating bodies are at the separated position, a downstream end of the sheet conveyed in the first conveying direction by the first conveying unit passes between the pair of discharge rotating bodies and an upstream end of the sheet conveyed in the first conveying direction by the first conveying unit passes through the first conveying unit, and then, without conveying the sheet whose upstream end in the first conveying direction has passed the first conveying unit in the second conveying direction by the second conveying unit, and while the sheet is moving in the first conveying direction, one of the pair of alignment plates in the width direction is moved in a predetermined shift direction that is a direction toward the other side in the width direction, thereby shifting the upstream end of the sheet in the first conveying direction. a sorting and discharging process including: performing a shift operation to move a position of a sheet whose end has passed the first conveying section in the predetermined shift direction; after the shift operation, retracting the alignment plate on one side in the width direction from the sheet that has been shifted in the shift operation and moving the pair of discharge rotors to the nip position, and then discharging the sheet to the shift position of the stacking section by the pair of discharge rotors multiple times to stack an unbound first sheet stack; and discharging the sheets transported by the first conveying section one by one by the pair of discharge rotors to a position shifted upstream of the shift position on the stacking section in the predetermined shift direction without transporting the sheets in the second conveying direction by the second conveying section multiple times to stack an unbound second sheet stack. A sheet processing apparatus capable of performing the above. (Configuration 10) When the sheet conveyed by the first conveying unit has a first size, a first shift discharge process can be executed, and when the sheet conveyed by the first conveying unit has a second size, the length of the sheet conveyed by the first conveying unit in the first conveying direction is shorter than that of the sheet of the first size, a second shift discharge process can be executed, The first shift discharge process includes: The sheet is transported in the first transport direction by the first transport unit; When the pair of discharge rotating bodies are in the separated position, a downstream end in the first conveying direction of the sheet conveyed in the first conveying direction by the first conveying passes between the pair of discharge rotating bodies, and an upstream end in the first conveying direction of the sheet conveyed in the first conveying direction by the first conveying unit passes through the first conveying unit, a sheet whose upstream end in the first transport direction has passed through the first transport section is sandwiched between the pair of alignment plates while the sheet is moving in the first transport direction without being transported in the second transport direction by the second transport section, and in this state, the pair of alignment plates are moved in a shift direction that is one of both sides in the width direction, thereby performing a shift operation to move a position of the sheet whose upstream end in the first transport direction has passed through the first transport section in the shift direction; a process of retracting the pair of alignment plates in the width direction from the sheet that has been shifted by the pair of alignment plates after the shift operation, and moving the pair of discharge rotors to the nip position, and then discharging the sheet to the stacking section by the pair of discharge rotors, 10. The sheet processing apparatus according to configuration 9, wherein the second shift discharge process is the sorting discharge process. (Configuration 11) an image forming apparatus having an image forming unit that forms an image on a sheet; 11. An image forming system comprising: the sheet processing apparatus according to any one of configurations 1 to 10, which performs binding processing on sheets on which images have been formed by the image forming unit. [Explanation of symbols]

[0152] 100 Image forming apparatus 103... Image forming unit 200 Sheet processing device 211A, 212A: Pre-processing rollers (first conveying section) 220 Processing tray (mounting section) 230A: Upper discharge roller (discharge rotor) 230B: Lower discharge roller (discharge rotor) 240A···Scraping paddle (second conveying section) 271A, 271B...Matching plate 290... Rear end regulating member (butting portion) 300···Loading tray (loading section) 320A···Discharge sheet pick-up paddle (picking up part) 400··· Staple unit (processing section) 1000···Image forming system MT12... Processing motor (moving part) MT16 Front side (F side) alignment plate movement motor (drive unit) MT17 Rear side (R side) alignment plate movement motor (drive unit)

Claims

1. a first conveying unit that conveys the sheet in a first conveying direction; a placement section for placing the sheet conveyed by the first conveying section; an abutting portion against which an upstream edge of the sheet on the placement portion in the first transport direction is abutted; a second conveying section that conveys the sheet in a second conveying direction in which an upstream edge of the sheet on the placement section in the first conveying direction faces the abutting section; a pair of alignment plates arranged on both sides of the sheet abutted against the abutting portion with respect to a width direction of the sheet intersecting the first conveying direction, the pair of alignment plates aligning the sheet abutted against the abutting portion in the width direction; a drive unit that moves the pair of alignment plates in the width direction; a processing section that performs a binding process on a sheet bundle including a plurality of sheets that have been aligned in the width direction by the pair of alignment plates; a stacking section disposed downstream of the placement section in the first transport direction and configured to stack the sheets transported in the first transport direction by the first transport section; a pair of discharge rotors configured to discharge the sheet conveyed in the first conveying direction by the first conveying unit to the stacking unit; a moving unit that moves a position of at least one of the pair of discharge rotors to a nip position where the pair of discharge rotors nip a sheet and a separated position where the pair of discharge rotors are separated from each other, a binding discharge process in which, after the first conveying unit conveys a sheet in the first conveying direction, the sheet conveyed by the first conveying unit is conveyed in the second conveying direction on the placement unit by the second conveying unit, so that a downstream end edge of the sheet in the second conveying direction is abutted against the abutment unit, and the sheet is aligned at the binding position by the pair of alignment plates, and this is repeated, thereby performing the binding process on the multiple sheets positioned at the binding position by the processing unit, and discharging the multiple sheets that have been subjected to the binding process to the stacking unit by the pair of discharge rotating bodies; a sheet is conveyed in the first conveying direction by the first conveying unit, and in a state where the pair of discharge rotating bodies are at the separated position, a downstream end in the first conveying direction of the sheet conveyed in the first conveying direction by the first conveying unit passes between the pair of discharge rotating bodies and an upstream end in the first conveying direction of the sheet conveyed in the first conveying direction by the first conveying unit passes through the first conveying unit, the sheet whose upstream end in the first conveying direction has passed through the first conveying unit is sandwiched between the pair of alignment plates without being conveyed in the second conveying direction by the second conveying unit and while the sheet is moving in the first conveying direction, the pair of alignment plates are moved in a shift direction that is one of both sides in the width direction in this state, so that the upstream end in the first conveying direction is a sorting and discharging process including: performing a shift operation to move a position of a sheet that has passed through the first conveying unit in the shift direction; after the shift operation by the pair of alignment plates, retracting the pair of alignment plates in the width direction from the sheet that has been shifted by the shift operation and moving the pair of discharge rotors to the nip position; and then discharging the sheets one by one to the shift position on the stacking unit by the pair of discharge rotors, thereby repeating this process multiple times to stack an unbound first sheet stack; and discharging the sheets transported by the first conveying unit one by one to a position shifted upstream of the shift position on the stacking unit in the shift direction by the pair of discharge rotors, without transporting the sheets in the second conveying direction by the second conveying unit, thereby repeating this process multiple times to stack an unbound second sheet stack; A sheet processing apparatus capable of performing the above.

2. the moving unit is capable of moving a position of at least one of the pair of discharge rotors between a first separation position where the pair of discharge rotors are spaced apart from the nip position and a second separation position where the pair of discharge rotors are spaced apart from the nip position and the distance between the pair of discharge rotors is narrower than the first separation position, 2. The sheet processing apparatus according to claim 1, wherein, in the sorting and discharging process, when the downstream end in the first conveying direction of a sheet transported in the first conveying direction by the first conveying unit passes between the pair of discharge rotors while the pair of discharge rotors is in the first separation position, the pair of discharge rotors are moved to the second separation position, and the sheet whose upstream end in the first conveying direction has passed the first conveying unit is not transported in the second conveying direction by the second conveying unit, and the sheet is clamped between the pair of alignment plates while moving in the first conveying direction, thereby performing the shift operation.

3. 2. The sheet processing apparatus according to claim 1, wherein the speed at which the drive unit moves the pair of alignment plates when clamping a sheet whose upstream end in the first transport direction has passed the first transport section without the second transport section transporting the sheet in the second transport direction and while the sheet is moving in the first transport direction is slower than the speed at which the drive unit moves the pair of alignment plates when performing the shift operation.

4. 2. The sheet processing apparatus according to claim 1, wherein, in the sorting and discharging process, after the shifting operation by the pair of alignment plates, the pair of alignment plates are retracted to a first evacuation position away from the sheet that has been shifted, and the sheet is transported in the first transport direction by the pair of discharge rotors, and before the upstream end in the first transport direction of the sheet transported by the pair of discharge rotors passes through the discharge nip portion formed by the pair of discharge rotors at the nip position, the pair of alignment plates are retracted to a second evacuation position further away from the sheet than the first evacuation position, and the sheet is discharged to the stacking portion by the pair of discharge rotors while the pair of alignment plates are in the second evacuation position.

5. a first conveying unit that conveys the sheet in a first conveying direction; a placement section for placing the sheet conveyed by the first conveying section; an abutting portion against which an upstream edge of the sheet on the placement portion in the first transport direction is abutted; a second conveying section that conveys the sheet in a second conveying direction in which an upstream edge of the sheet on the placement section in the first conveying direction faces the abutting section; a pair of alignment plates that are disposed on both sides of the sheet abutted against the abutting portion with respect to a width direction of the sheet intersecting the first conveying direction, and align the sheet abutted against the abutting portion in the width direction; a drive unit that moves the pair of alignment plates in the width direction; a processing section that performs a binding process on a sheet bundle including a plurality of sheets that have been aligned in the width direction by the pair of alignment plates; a stacking section disposed downstream of the placement section in the first transport direction and configured to stack the sheets transported in the first transport direction by the first transport section; a pair of discharge rotors configured to discharge the sheet conveyed in the first conveying direction by the first conveying unit to the stacking unit; a moving unit that moves a position of at least one of the pair of discharge rotors to a nip position where the pair of discharge rotors nip a sheet and a separated position where the pair of discharge rotors are separated from each other, a binding discharge process in which, after the first conveying unit conveys a sheet in the first conveying direction, the sheet conveyed by the first conveying unit is conveyed in the second conveying direction on the placement unit by the second conveying unit, so that a downstream end edge of the sheet in the second conveying direction is abutted against the abutment unit, and the sheet is aligned at the binding position by the pair of alignment plates, and this is repeated, thereby performing the binding process on the multiple sheets positioned at the binding position by the processing unit, and discharging the multiple sheets that have been subjected to the binding process to the stacking unit by the pair of discharge rotating bodies; a sheet is conveyed in the first conveying direction by the first conveying unit, and in a state in which the pair of discharge rotating bodies are at the separated position, a downstream end of the sheet conveyed in the first conveying direction by the first conveying unit passes between the pair of discharge rotating bodies and an upstream end of the sheet conveyed in the first conveying direction by the first conveying unit passes through the first conveying unit, and then, without conveying the sheet whose upstream end in the first conveying direction has passed the first conveying unit in the second conveying direction by the second conveying unit, and while the sheet is moving in the first conveying direction, one of the pair of alignment plates in the width direction is moved in a predetermined shift direction that is a direction toward the other side in the width direction, thereby shifting the upstream end of the sheet in the first conveying direction. a sorting and discharging process including: performing a shift operation to move a position of a sheet whose end has passed the first conveying section in the predetermined shift direction; after the shift operation, retracting the alignment plate on one side in the width direction from the sheet that has been shifted in the shift operation and moving the pair of discharge rotors to the nip position, and then discharging the sheets to the shift position of the stacking section by the pair of discharge rotors multiple times to stack an unbound first sheet stack; and discharging the sheets transported by the first conveying section one by one by the pair of discharge rotors to a position shifted upstream of the shift position on the stacking section in the predetermined shift direction without transporting the sheets in the second conveying direction by the second conveying section multiple times to stack an unbound second sheet stack; A sheet processing apparatus capable of performing the above.

6. When the sheet conveyed by the first conveying unit has a first size, a first shift discharge process can be executed, and when the sheet conveyed by the first conveying unit has a second size, the length of the sheet conveyed by the first conveying unit in the first conveying direction is shorter than that of the sheet of the first size, a second shift discharge process can be executed, The first shift discharge process includes: The sheet is transported in the first transport direction by the first transport unit; When the pair of discharge rotating bodies are in the separated position, a downstream end in the first transport direction of the sheet transported in the first transport direction by the first transport passes between the pair of discharge rotating bodies, and an upstream end in the first transport direction of the sheet transported in the first transport direction by the first transport unit passes through the first transport unit, a sheet whose upstream end in the first transport direction has passed through the first transport section is sandwiched between the pair of alignment plates while being moved in the first transport direction by the second transport section without being transported in the second transport direction by the second transport section, and in this state, the pair of alignment plates are moved in a shift direction which is one of both sides in the width direction, thereby performing a shift operation of moving a position of the sheet whose upstream end in the first transport direction has passed through the first transport section in the shift direction; a process of retracting the pair of alignment plates in the width direction from the sheet that has been shifted by the pair of alignment plates after the shift operation, and moving the pair of discharge rotors to the nip position, and then discharging the sheet to the stacking section by the pair of discharge rotors, The sheet processing apparatus according to claim 5 , wherein the second shift discharge process is the sorting discharge process.

7. an image forming apparatus having an image forming unit that forms an image on a sheet; 7. An image forming system comprising: the sheet processing apparatus according to claim 1, which performs a binding process on the sheets on which the images are formed by the image forming unit.

Images