Sheet processing device and image forming system

Abstract

The present invention provides a sheet processing device and an image forming system that suppress sheet skew when shifting and aligning sheets in a mode that performs corner binding on a stack of sheets on a processing tray. [Solution] In the corner binding mode, there are sheets that undergo shift alignment, where the sheets are shifted one by one on the processing tray to align. Among the sheets that require shift alignment, there are first sheets that do not come off the rear end restricting members on both sides in the width direction when the sheet is shifted, and second sheets that come off in part. In the case of the first sheet, the sheet is shifted while being gripped with a first gripping force by the knurled belt, which forces the rear end of the first sheet against the rear end restricting member. In the case of the second sheet, the sheet is shifted while being gripped with a second gripping force weaker than the first gripping force by the knurled belt, or without gripping, thereby suppressing the skew of the sheet during shifting.

Description

Technical Field

[0001] The present invention relates to a sheet processing apparatus that performs binding processing on a sheet, and an image forming system.

Background Art

[0002] In Patent Document 1, in a sheet processing apparatus that performs binding processing on a sheet, when performing binding processing on a sheet, the rear end of the sheet placed on the processing tray is abutted against a plurality of provided rear end restricting members, and the abutted sheet is width-aligned by an alignment plate, and by repeating this, a sheet bundle is formed on the processing tray, and binding processing is performed on the sheet bundle with a stapler or the like.

[0003] When performing binding processing on the corner of a sheet with such a sheet processing apparatus, when center-aligning the sheet on the processing tray (width-aligning the sheet by sandwiching the sheet with the alignment plates on both sides at the position where the rear end of the sheet abuts against the rear end restricting member), depending on the sheet width, the position where the binding processing is performed on the sheet and the rear end restricting member may overlap, and corner binding cannot be performed. Therefore, for sheets of such a width, the sheet bundle is formed at the corner binding position on the processing tray by shifting the sheets one by one in the width direction to the corner binding position for corner binding and then performing width alignment (this is called shift alignment).

[0004] When performing shift alignment, one alignment plate waits at the alignment position, and the other alignment plate pushes the edge in the sheet width direction to shift the sheet toward one alignment plate. Since the sheet is shifted without being sandwiched by the alignment plates, especially large sheets that are larger than a predetermined size and are vertical (the length in the conveyance direction is longer than the length in the sheet width direction) are likely to skew. Therefore, in order to suppress the skew of large sheets during shift alignment, the sheets are shifted one by one by the alignment plate while scraping the sheets in the direction of abutting the rear end of the sheet against the rear end restricting member with a scraping force that allows the large sheets to be shifted.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-20999 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, when shifting a sheet with a width narrower than the specified size, the rear end of the sheet may detach from the upstream rear end regulating member in the shift direction of the multiple rear end regulating members. If the sheet continues to be tucked in with the same tucking force as a large sheet in this state, the contact pressure of the rear end of the sheet against the rear end regulating member increases, creating resistance during shifting. If the sheet is pushed with only one alignment plate while the rear end is braked in this way, the sheet may skew, and the corner of the sheet may come into contact with the stapler, making it impossible to position the sheet at the corner binding position, potentially resulting in missing pages.

[0007] The present invention aims to provide a sheet processing apparatus and an image forming apparatus that can suppress sheet skew not only when shifting and aligning sheets that are larger than a predetermined size and have a vertical orientation, but also when shifting and aligning sheets that have a width narrower than a predetermined size. [Means for solving the problem]

[0008] One aspect of the present invention is a first transport unit that transports a sheet in a first transport direction; a placement unit that places the sheet transported by the first transport unit; abutment unit against which the upstream edge of the sheet in the first transport direction on the placement unit abuts; a second transport unit that transports the sheet in a second transport direction toward the abutment unit, with respect to the width direction of the sheet intersecting the first transport direction; a first alignment plate and a second alignment plate that are arranged on both sides of the sheet abutted against the abutment unit with respect to the width direction of the sheet intersecting the first transport direction, and that perform alignment processing on the sheet in the width direction by contacting both ends of the sheet in the width direction of the sheet abutted against the abutment unit; a binding processing unit that performs binding processing on a sheet bundle consisting of a plurality of sheets formed on the placement unit after the alignment processing; and the binding processing unit The apparatus comprises a loading section for loading the sheet bundles that have been treated, a discharge section for discharging the sheet bundles from the loading section, a second transport section, a first alignment plate, a control unit for controlling the second alignment plate and the binding processing section, wherein a plurality of abutment sections are provided in the width direction, and when corner binding is performed on the corners of the sheet bundles, the control unit moves the binding processing section toward the second alignment plate, which is in a more aligned position than the abutment section in the width direction, and with the second alignment plate waiting in the aligned position, it performs shift alignment to align the sheet bundles by repeatedly shifting the sheets placed on the loading section toward the second alignment plate using the first alignment plate and then aligning them, and corner binding can be performed on the shift-aligned sheet bundles. The sheet processing apparatus is characterized in that, when shifting a first sheet in which the edge of the sheet on the first alignment plate side is located upstream in the shift direction of the shift direction of the furthest upstream abutment member in the shift direction and the length in the second transport direction is longer than the length of the sheet in the width direction, the second transport unit applies a force toward the abutment member to the sheet with a first transport force while the first alignment plate shifts the sheet in the shift direction; when shifting a second sheet in which the edge of the sheet on the first alignment plate side is located downstream in the shift direction of the shift direction of the furthest upstream abutment member in the shift direction, the second transport unit applies a force toward the abutment member to the sheet with a second transport force weaker than the first transport force while the first alignment plate shifts the sheet in the shift direction.

[0009] One aspect of the present invention is a first transport unit that transports a sheet in a first transport direction; a placement unit that places the sheet transported by the first transport unit; abutment unit against which the upstream edge of the sheet in the first transport direction on the placement unit abuts; a second transport unit that transports the sheet in a second transport direction toward the abutment unit, with respect to the width direction of the sheet intersecting the first transport direction; a first alignment plate and a second alignment plate that are arranged on both sides of the sheet abutted against the abutment unit with respect to the width direction of the sheet intersecting the first transport direction, and that perform alignment processing on the sheet in the width direction by contacting both ends of the sheet in the width direction of the sheet abutted against the abutment unit; a binding processing unit that performs binding processing on a sheet bundle consisting of a plurality of sheets formed on the placement unit after the alignment processing; and the binding processing unit The apparatus comprises a loading section for loading the sheet bundles that have been treated, a discharge section for discharging the sheet bundles from the loading section, a second transport section, a first alignment plate, a control unit for controlling the second alignment plate and the binding processing section, wherein a plurality of abutment sections are provided in the width direction, and when corner binding is performed on the corners of the sheet bundles, the control unit moves the binding processing section toward the second alignment plate, which is in a more aligned position than the abutment section in the width direction, and with the second alignment plate waiting in the aligned position, it performs shift alignment to align the sheet bundles by repeatedly shifting the sheets placed on the loading section toward the second alignment plate using the first alignment plate and then aligning them, and corner binding can be performed on the shift-aligned sheet bundles.The sheet processing apparatus is characterized in that, when shifting a first sheet in which the edge of the sheet on the first alignment plate side is located upstream of the furthest upstream abutment member in the shift direction and the length in the second transport direction is longer than the length of the sheet in the width direction, the first alignment plate shifts the sheet in the shift direction while applying a force toward the abutment member to the sheet by the second transport unit, and when shifting a second sheet in which the edge of the sheet on the first alignment plate side is located downstream of the furthest upstream abutment member in the shift direction, the first alignment plate shifts the sheet in the shift direction without applying a force toward the abutment member to the sheet by the second transport unit. [Effects of the Invention]

[0010] The present invention makes it possible to suppress seat skew when shifting and aligning the seat. [Brief explanation of the drawing]

[0011] [Figure 1] A schematic cross-sectional view of the image forming system according to the embodiment. [Figure 2] A schematic cross-sectional view of the sheet processing apparatus according to the embodiment. [Figure 3] A schematic perspective view showing the sheet processing apparatus according to the embodiment with the upper cover removed. [Figure 4] (a) A view of the alignment plate on the processing tray as seen from the width direction, (b) A view of the alignment plate as seen from the downstream side in the sheet transport direction, and (c) A perspective view of the alignment plate according to the embodiment. [Figure 5] (a) A perspective view of the area around the processing tray in the home position of the sheet processing apparatus according to the embodiment, and (b) A schematic cross-sectional view of the sheet processing apparatus. [Figure 6] A view from the width direction of (a) the discharge roller, (b) the scraping paddle, and (c) the rear end dropping member in the home position of the sheet processing apparatus according to the embodiment. [Figure 7] Perspective view around the processing tray and schematic cross-sectional view of the sheet processing apparatus according to the embodiment when discharging the sheet. [Figure 8] Views from the width direction of the sheet processing apparatus according to the embodiment when discharging the sheet, showing (a) the state of the discharge roller, (b) the state of the scraping paddle, and (c) the state of the rear-end dropping member, respectively. [Figure 9] Perspective view around the processing tray and schematic cross-sectional view of the sheet processing apparatus according to the embodiment when scraping in the sheet. [Figure 10] Views from the width direction of the sheet processing apparatus according to the embodiment when scraping in the sheet, showing (a) the state of the discharge roller, (b) the state of the scraping paddle, and (c) the state of the rear-end dropping member, respectively. [Figure 11] Perspective view around the roulette belt drive mechanism according to the first embodiment. [Figure 12] Table showing the correspondence between each motor and each component of the sheet processing apparatus according to the embodiment. [Figure 13] Block diagram showing the control configuration of the sheet processing apparatus according to the embodiment. [Figure 14] Plan view of the sheet processing apparatus according to the embodiment, with a part omitted and viewed from above. [Figure 15] Flowchart showing an example of the control flow of the sheet processing apparatus according to the embodiment. [Figure 16] Flowchart showing an example of the control flow of the sheet processing apparatus according to the embodiment, particularly showing the flow when forming a sheet bundle on the processing tray. [Figure 17] Schematic view (a) of the main part of the sheet processing apparatus when transporting the first sheet in the staple mode according to the embodiment, viewed from above, and schematic cross-sectional view (b). [Figure 18] Schematic view (a) of the main part of the sheet processing apparatus when performing a switch-back transport of the first sheet in the staple mode according to the embodiment, viewed from above, and schematic cross-sectional view (b). [Figure 19]Schematic diagram (a) of the main part of the sheet processing apparatus when aligning the shift of the first sheet in the staple mode according to the embodiment, viewed from above, and schematic cross-sectional view (b). [Figure 20] Schematic diagram (a) of the main part of the sheet processing apparatus when re-feeding the first sheet in the staple mode according to the embodiment, viewed from above, and schematic cross-sectional view (b). [Figure 21] Schematic diagram (a) of the main part of the sheet processing apparatus when performing a switchback conveyance of the second first sheet in the staple mode according to the embodiment, viewed from above, and schematic cross-sectional view (b). [Figure 22] Schematic diagram (a) of the main part of the sheet processing apparatus when aligning the shift of the second first sheet in the staple mode according to the embodiment, viewed from above, and schematic cross-sectional view (b). [Figure 23] Schematic diagram (a) of the main part of the sheet processing apparatus when re-feeding the second first sheet in the staple mode according to the embodiment, viewed from above, and schematic cross-sectional view (b). [Figure 24] Schematic diagram (a) of the main part of the sheet processing apparatus when discharging a sheet bundle of the first sheet in the staple mode according to the embodiment, viewed from above, and schematic cross-sectional view (b). [Figure 25] Schematic diagram (a) of the main part of the sheet processing apparatus when conveying the first second sheet in the staple mode according to the embodiment, viewed from above, and schematic cross-sectional view (b). [Figure 26] Schematic diagram (a) of the main part of the sheet processing apparatus when performing a switchback conveyance of the first second sheet in the staple mode according to the embodiment, viewed from above, and schematic cross-sectional view (b). [Figure 27] Schematic diagram (a) of the main part of the sheet processing apparatus when aligning the shift of the first second sheet in the staple mode according to the embodiment, viewed from above, and schematic cross-sectional view (b). [Figure 28] Schematic diagram (a) of the main part of the sheet processing apparatus when re-feeding the first second sheet in the staple mode according to the embodiment, viewed from above, and schematic cross-sectional view (b). [Figure 29](a) A schematic diagram of the main part of the sheet processing device viewed from above during switchback transport of the second sheet in the stapling mode according to the embodiment, and (b) a schematic cross-sectional view of the configuration. [Figure 30] (a) A schematic diagram of the main part of the sheet processing device viewed from above during the shift alignment of the second sheet in the stapling mode according to the embodiment, and (b) a schematic cross-sectional view of the configuration. [Figure 31] (a) A schematic diagram of the main part of the sheet processing device viewed from above, and (b) a schematic cross-sectional view of the configuration, when the second sheet is re-scooped in the stapling mode according to the embodiment. [Figure 32] (a) A schematic diagram of the main part of the sheet processing device viewed from above, and (b) a schematic cross-sectional view of the configuration, when the sheet bundle of the second sheet is discharged in the stapling mode according to the embodiment. [Figure 33] (a) A schematic diagram of the main part of the sheet processing device viewed from above when the upper discharge roller of the switchbackless shift discharge process according to the embodiment is lowered, and (b) a schematic cross-sectional view of the configuration. [Figure 34] (a) A schematic diagram of the main part of the sheet processing device viewed from above during the movement of the alignment plate in the switchbackless shift discharge process according to the embodiment, and (b) a schematic cross-sectional view of the configuration. [Figure 35] (a) A schematic diagram of the main part of the sheet processing device viewed from above during sheet shifting by the alignment plate in the switchbackless shift discharge process according to the embodiment, and (b) a schematic cross-sectional view of the configuration. [Figure 36] (a) A schematic diagram of the main part of the sheet processing device viewed from above, and (b) a schematic cross-sectional view of the configuration, at the time of completion of sheet discharge in the switchbackless shift discharge process according to the embodiment. [Figure 37] A perspective view showing a stack of unbound sheets formed on a loading tray, moved in the shift direction. [Modes for carrying out the invention]

[0012] Embodiments will be described using Figures 1 to 37. First, the schematic configuration of the image forming system of this embodiment will be described using Figure 1.

[0013] [Image Forming System] Figure 1 is a cross-sectional view showing the schematic configuration of the image forming system of this embodiment. The image forming system 1000 includes an image forming apparatus 100 and a sheet processing apparatus 200. The image forming apparatus 100 is a copier, printer, facsimile, or a multifunction device having multiple of these functions, and forms an image on a sheet such as paper or a plastic sheet. In this embodiment, it is an electrophotographic printer, and the sheet on which the toner image has been formed is discharged from the discharge port 101. Note that the image forming apparatus 100 may also be an inkjet type image forming apparatus.

[0014] The image forming apparatus 100 of this embodiment comprises an image forming apparatus body 110 and an image reading device 120 positioned above the image forming apparatus body 110. In the image forming apparatus body 110, a toner image is formed on a sheet in the image forming unit 103. The image forming unit 103 of this embodiment forms a full-color toner image using four toners: yellow (y), magenta (m), cyan (c), and black (k). Therefore, the image forming unit 103 has multiple image forming stations that form toner images of each color. The configuration of each color image forming station is the same except for the color of the toner.

[0015] In each color image forming station, the surface of the photosensitive drum 10 is charged by a charging member 11, and the surface is exposed by an exposure device (not shown) to form an electrostatic latent image on the photosensitive drum 10. This electrostatic latent image is then developed with a developer by a developing device 12 to form a toner image. The toner image formed on the photosensitive drum 10 is first transferred onto the intermediate transfer belt 14 by a primary transfer roller 13. Any remaining toner on the photosensitive drum 10 after the first transfer is removed by a drum cleaner 15.

[0016] These charging, exposure, development, primary transfer, and drum cleaning cycles are repeated similarly at each image forming station, and toner images of yellow, magenta, cyan, and black are sequentially transferred onto the intermediate transfer belt 14, forming a full-color toner image.

[0017] On the other hand, the image forming apparatus 100 has a plurality of cassettes 20 for storing sheets. Sheets stored in each cassette 20 are transported to the sheet transport path 22 by the rotation of the feed roller 21 and reach the registration roller 23. The registration roller 23 feeds the sheet to the secondary transfer section 17, which is formed by the intermediate transfer belt 14 and the secondary transfer roller 16, in time with the toner image on the intermediate transfer belt 14. The multi-color toner image formed on the intermediate transfer belt 14 is transferred to the sheet all at once in the secondary transfer section 17. After secondary transfer, any remaining toner or paper dust on the intermediate transfer belt 14 is removed by the belt cleaner 18.

[0018] The sheet that has passed through the secondary transfer section 17 is transported to the fixing device 30, which acts as an image heating device. The fixing device 30 has a heating roller 31 and a pressure roller 32, and the heating roller 31 and the pressure roller 32 form a heating nip section that grips and transports the sheet. The sheet transported to the fixing device 30 is heated and pressurized in the heating nip section, and the unfixed toner image is fixed onto the sheet. The sheet with the fixed toner image is transported along the discharge transport path 24 and discharged outside the machine from the discharge port 101 by the discharge roller 25, completing the series of image forming operations.

[0019] As described above, the image forming apparatus 100 of this embodiment comprises an image forming apparatus body 110 and an image reading device 120. The image reading device 120 reads the image on the document placed on the platen glass 122 using an image reading unit 121 and sends the read image signal to the image forming apparatus body 110. An automatic document feeder (ADF) 123 is also located above the image reading device 120 to transport the document to the image reading unit 121. The image reading device 120 can also read images on documents fed by the automatic document feeder 123.

[0020] The image forming apparatus main body 110 has a first housing section 111 in which the image forming unit 103 and other components are arranged, and a second housing section 112 in which the discharge transport path 24 and discharge rollers 25 are arranged, with the second housing section 112 located above the first housing section 111. The image reading device 120 is located above the second housing section 112. The second housing section 112 is also equipped with an operation panel 102, which allows the user to input instructions (printing conditions, mode settings, etc.) to the image forming apparatus 100 and the sheet processing device 200.

[0021] In this embodiment, the image forming apparatus has an internal space 130 surrounded by the first housing 111, the second housing 112, and the image reading device 120. The sheet is discharged into the internal space 130 from the discharge port 101 of the image forming apparatus body 110. A sheet processing device 200 and the like can be attached to and removed from this internal space 130. In this embodiment, the image forming system 1000 is configured with the sheet processing device 200 attached, but other sheet processing devices may also be attached.

[0022] The sheet processing device 200 is connected to the discharge port 101 and receives the sheets discharged from the discharge port 101. As will be described in more detail later, the sheet processing device 200 can perform predetermined processing on these sheets, such as binding.

[0023] [Sheet processing device] The configuration of the sheet processing apparatus 200 of this embodiment will be described using Figures 2 to 10(c). First, the overall configuration of the sheet processing apparatus 200 will be described using Figures 2 and 3. In the following description, the front side (front (F) side) is one side (the front side in Figure 2, the front right side in Figure 3) with respect to the width direction of the sheet perpendicular to the sheet transport direction, and is the side on which the operator operates the image forming system 1000, for example, the side on which the operation panel 102 is installed. The rear side (rear (R) side) is the opposite side from the front side, and is the other side (the back side in Figure 2, the back left side in Figure 3).

[0024] [Overall configuration of the sheet processing device] The sheet processing apparatus 200 includes a transport path 210A, a first transport section 211 having a pair of pre-processing rollers 211A and 212A as transport rollers, a processing tray 220 as a loading section, an upper discharge roller (nip member) 230A and a lower discharge roller 230B as a pair of discharge rotating bodies (discharge section), a scraping paddle 240A as a second transport section, rear end dropping members 250A and 250B as a sheet dropping section, a matching section 270A as a first and second shift section, a return member 280, a rear end regulating member 290 as a stopper section, a loading tray 300 as a loading section, and a discharge sheet scraping paddle (sheet pressing paddle) 320A as a scraping section. Sheets received from the image forming apparatus 100 are transported to the transport path 210A.

[0025] The sheets transported from the transport path 210A are either directly discharged to the loading tray 300 or placed on the processing tray 220, depending on the mode of processing the sheets. Direct discharge to the loading tray 300 means that the sheets are discharged to the loading tray 300 without being transported back 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 sheet bundles that have been stapled by the stapling unit 400 or sheet bundles that have been bound without staples by the stapleless binding unit 500 (see Figure 14, etc.) are discharged to the loading tray 300, and a mode in which sheets are discharged to the loading tray 300 without stapling by the stapling unit 400. In this embodiment, the sheets are not placed on the processing tray 220, but are aligned by a pair of alignment plates (movable members) 271A of the alignment unit 270A. Furthermore, sheet alignment is possible in the processing tray 220, and the sheets placed on the processing tray 220 can be stapled or staple-free using the stapling unit 400 or the staple-free stapling unit 500. In addition, the sheets or sheet bundles placed on the processing tray 220 can be discharged to the loading tray 300 by a pair of discharge rotating bodies, such as the upper discharge roller 230A and the lower discharge roller 230B. The configuration of each part will be described in detail below.

[0026] [Transport path] The transport path 210A is a path for transporting the sheet in a first transport direction (a predetermined direction), and has an upper guide 2101 that guides the upper surface of the sheet being transported, and a lower guide 2102 that guides the lower surface of the sheet. The transport path 210A is arranged with a first transport section 211 having a pair of pre-processing rollers 211A and 212A as transport rollers, and upstream rollers (inlet rollers) 213a and 213b. These are arranged in pairs so as to be spaced apart in the width direction of the sheet (arrow γ direction in Figure 3) that intersects the sheet transport direction (first transport direction, arrow β direction in Figure 2 (left and right direction)).

[0027] The pre-processing rollers 211A and 212A are a pair of conveying rotating bodies that transport the sheet, with at least one rotating while gripping the sheet. The upstream rollers 213a and 213b also rotate while gripping the sheet. The upstream rollers 213a and 213b are located at the entrance of the sheet processing device 200, receiving the sheet transported from the upstream side of the sheet processing device 200 and transporting it to the transport path 210A. The sheet that has passed through the transport path 210A then reaches the pre-processing rollers 211A and 212A.

[0028] The pre-processing rollers 211A and 212A form a pre-processing nip section 211a capable of gripping and conveying the sheet. The sheet is then gripped by the pre-processing nip section 211a and conveyed in the first conveying direction, and the sheet is discharged from the conveying path 210A. The pre-processing rollers 211A and 212A can be in contact with or separated from each other, or the nip pressure can be changed.

[0029] [Processing tray] The processing tray 220, which serves as the sheet placement section, is positioned downstream of the sheet transport direction (first transport direction) of the transport path 210A and vertically below the transport path 210A. The processing tray 220 is also inclined with respect to the horizontal plane such that the upstream side in the first transport direction is lower than the downstream side. The processing tray 220 temporarily places sheets that have been transported downstream in the first transport direction by the pre-processing rollers 211A and 212A. The processing tray 220 can also stack multiple sheets, and the alignment section 270A on the processing tray 220 aligns the sheets in the width direction and moves them in the width direction (sheet shifting). Furthermore, a rear end regulating member 290 is positioned at the upstream end of the processing tray 220 in the first transport direction, which abuts the upstream edge (rear end of the sheet) of the sheet placed on the processing tray 220. Furthermore, a portion of the processing tray 220 (for example, the downstream end in the first transport direction) may protrude vertically upward from the transport path 210A.

[0030] Furthermore, a staple unit 400, which functions as a processing unit (stapler), is positioned upstream of the processing tray 220 in the first transport direction. The staple unit 400 performs a predetermined stapling process (binding process) at a first binding position P1 (see Figure 19) on the sheet bundle that has been aligned in the width direction and restricted at the rear end by the processing tray 220. The staple unit 400 can change the staple position relative to the sheet bundle and moves according to the staple position. Note that the predetermined process may be other processes such as punching, in addition to stapling. The sheets or sheet bundles placed on the processing tray 220 are discharged to the loading tray 300 by the upper discharge roller 230A and the lower discharge roller 230B, as will be described later.

[0031] As shown in Figure 14 and other figures described later, a stapleless stapling unit 500 is positioned upstream of the processing tray 220 in the first transport direction, and on one side in the width direction (rear side, right side in Figure 14) of the sheets placed on the processing tray 220. The stapleless stapling unit 500 performs stapleless stapling (hereinafter also referred to as "stapleless stapling") on the sheet bundle shifted to the rear side by a pair of alignment plates 271A and 271B at the second stapling position P2 (see Figures 15 and 20). A detailed explanation of the stapleless stapling unit 500 will be given later.

[0032] [Paddle for digging] The scraping paddle 240A, which serves as the second transport unit, transports the sheet on the processing tray 220 in a second transport direction (switchback transport) where the upstream edge in the first transport direction is toward the rear end regulating member 290. The scraping 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 pivot point 2403 that pivotably supports the paddle arm 2402. That is, the paddle arm 2402 is pivotable in the vertical direction around the pivot point 2403, and the paddle section 2401 is rotatably provided at the tip of the paddle arm 2402.

[0033] Such a scraping paddle 240A can swing around a pivot point 2403 between a return position in which the paddle portion 2401 contacts the upper surface of the sheet on the processing tray 220 and the sheet can be transported in the second transport direction, and an upper retracted position in which the paddle portion 2401 is retracted above the return position. The pivot point 2403 is located upstream in the first transport direction from the pre-processing nip portion 211a, which is the nip position where the sheet is gripped by the pre-processing rollers 211A and 212A, and vertically above the pre-processing nip portion 211a. The paddle arm 2402 extends downstream from the pivot point 2403 in the first transport direction, and the paddle portion 2401 is provided at its tip. Furthermore, as shown in Figure 3, a pair of scraping paddles 240A are arranged on both sides in the width direction of the upper discharge roller 230A, which will be described later.

[0034] [Rear end drop member] The rear end dropping members 250A and 250B, which serve as sheet dropping sections, are provided on both sides of the pair of scraping paddles 240A. That is, the pair of rear end dropping members 250A and 250B are positioned on both sides of the scraping paddles 240A in the width direction and, as will be described later, move vertically in conjunction with the scraping paddles 240A, so as to contact the upper surface on the upstream side in the first conveying direction of the sheet, they operate to drop the upstream end (rear end) of the sheet toward the processing tray 220. Note that the rear end dropping members 250A and 250B may be driven independently of the scraping paddles 240A.

[0035] These rear end drop members 250A and 250B have a pivot axis 2501 as the pivot center downstream in the first transport direction from the pre-processing rollers 211A and 212A, which are a pair of transport rollers. They extend upstream in the first transport direction from the pivot axis 2501 and are rotatable around the pivot axis 2501 to an upper position that allows the sheet to fall into the processing tray 220 when the sheet is transported by the pre-processing rollers 211A and 212A, and to a lower position that is located vertically below the upper position. In this embodiment, the upper position is when the tip of the rear end drop members 250A and 250B (upstream end in the first transport direction) is above the nip point N (Figure 2) of the pre-processing rollers 211A and 212A, and the lower position is when the tip of the rear end drop members 250A and 250B is below the nip point N of the pre-processing rollers 211A and 212A.

[0036] Furthermore, even if the rear end drop members 250A and 250B are in an upper position, if a sheet such as curled paper that deviates significantly from the specifications is conveyed from the pre-processing rollers 211A and 212A, or if an error occurs in the device, the sheet may touch the rear end drop members 250A and 250B and not fall into the processing tray 220. However, if the sheet can fall from the pre-processing rollers 211A and 212A into the processing tray 220 during normal operation, it can be said that the rear end drop members 250A and 250B in an upper position allow the sheet to fall. Also, the nip point N of the pre-processing rollers 211A and 212A is the downstream end in the first conveying direction if the pre-processing nip portion 211a that grips the sheet with the pre-processing rollers 211A and 212A has width in the first conveying direction.

[0037] The rear end dropping members 250A and 250B rotate from an upper position to a lower position, thereby contacting the sheet conveyed by the pre-processing rollers 211A and 212A from above and dropping the sheet into the processing tray 220 below. In particular, in this embodiment, the pivot axis 2501 of the rear end dropping members 250A and 250B is located downstream of the pre-processing rollers 211A and 212A in the first conveying direction, and extends upstream from the pivot axis 2501 in the first conveying direction. Therefore, when dropping the sheet conveyed by the pre-processing rollers 211A and 212A into the processing tray 220, the rear end dropping members 250A and 250B can strike the upstream side of the sheet in the first conveying direction. In particular, in this embodiment, when the rear end drop members 250A and 250B rotate from an upper position to a lower position, the tip portions of the rear end drop members 250A and 250B pass at the same position as the nip point N of the pre-processing rollers 211A and 212A with respect to the first conveying direction. As a result, the rear end of the sheet is less likely to remain on the pre-processing rollers 211A and 212A, and jamming can be suppressed. The rear end drop members 250A and 250B are positioned offset from the pre-processing rollers 211A and 212A with respect to the width direction perpendicular to the first conveying direction. Therefore, even with the above-described arrangement, the rear end drop members 250A and 250B and the pre-processing rollers 211A and 212A do not interfere with each other.

[0038] As described above, when the rear end drop members 250A and 250B are rotated to a lower position to drop the sheet into the processing tray 220, they guide the sheet toward the rear end restricting member 290 during switchback transport by the scraping paddle 240A in the lower position (in this embodiment, the sheet is passed to an intermediate guide for guiding the sheet to the rear end restricting member 290, but it may also be guided directly to the rear end restricting member 290). Note that when the rear end drop members 250A and 250B are in the lower position, if the sheet that has been transported via switchback is not curled, the sheet will not come into contact with the rear end drop members 250A and 250B. However, if the sheet end on the side of the rear end restricting member 290 is curled, the sheet will come into contact with the rear end drop members 250A and 250B and be passed to the intermediate guide or the rear end restricting member 290.

[0039] [Return component] The return member 280 further transports the sheet, which has been conveyed toward the rear end regulating member 290 by the scraping paddle 240A as described above, toward the rear end regulating member 290, and brings the rear end of the sheet into contact with the rear end regulating member 290, thereby regulating the position of the rear end of the sheet. Such a return member 280 is made of a knurled belt 281, and by rotating the knurled belt 281, the sheet, which has been conveyed toward the second transport direction by the scraping paddle 240A, is further scraped toward the second transport direction, bringing the rear end into contact with the rear end regulating member 290. The return member 280 is movable to a scraping position in which it scrapes the rear end of the sheet to abut against the rear end restricting member 290, a retracted position (home position) which is moved upward from the scraping position, a first raised position which is raised by a first amount from the scraping position between the scraping position and the retracted position, and a second raised position which is raised by a second amount greater than the first amount from the scraping position between the first raised position and the retracted position. When transporting the sheet toward the rear end restricting member 290, it moves to the scraping position; when transporting the sheet on the processing tray 220 toward the loading tray 300, it moves to the retracted position; and when performing shift alignment on the processing tray 220 as described later, it moves to the first raised position and the second raised position depending on the sheet size.

[0040] Figure 11 shows the rotational drive mechanism 2801 and the lifting drive mechanism 2802 of the return member 280. The rotational drive mechanism 2801 has a motor MT11, a shaft 282a, a drive belt 282b, a pulley 283 that rotates freely relative to the shaft 285, and a gear 284 that rotates freely relative to the shaft 285 together with the pulley 283. The driving force of the motor MT11 is transmitted from the shaft 282a to the drive belt 282b, and the rotation of the drive belt 282b causes the gear 284 that rotates with the pulley 283 to rotate, which in turn causes the knurled belt 281 connected to the gear 284 to rotate. A conveyor roller 213b is provided on the shaft 282a, and another drive belt 282c is provided on the pulley 283, and the drive belt 282c is connected to the pre-processing roller 212A. Therefore, the conveyor roller 213b, the pre-processing roller 212A, and the knurled belt 281 are rotated by the motor MT11. By rotating the motor MT11 in the forward direction, the knurled belt rotates in the counterclockwise direction shown in the diagram, and when the sheet on the processing tray 220 comes into contact with the knurled belt 281, the sheet is scraped towards the rear end regulating member 290.

[0041] The lifting drive mechanism 2802 includes a motor MT13, a sensor SN13, a shaft 285, and a knurling holder 281a fixed to the shaft 285a. The driving force of the motor MT13 is transmitted to the shaft 285, and as the shaft 285 rotates, the knurling holder 281a swings around the shaft 285. The control unit 203, described later, manages the amount of rotation of the shaft 285 based on the number of pulses from the motor MT13 from the off-edge of the sensor SN13, thereby moving the knurling belt 281 to the home position (retracted position), the gripping position, the first lifting position, and the second lifting position as described above. Note that the home position and the retracted position may be provided separately.

[0042] Here, the raising and lowering positions of the knurled belt 281 will be described. First, the retracted position is the highest position the knurled belt 281 is in between the processing tray 220 and the transport path 210A (lower guide). Also, the retracted position is located above the top sheet when 55 sheets, the maximum number of staples, are stacked on the processing tray 220, and is a position where the knurled belt 281 does not come into contact with the sheets. In this embodiment, this is the position where the flag of the sensor SN13 has passed between the light-emitting part and the light-receiving part and is off-edge, but it can be set as appropriate. With the knurled belt 281 in the retracted position, the stack of sheets on the processing tray 220 is discharged to the stacking tray 300.

[0043] Next, the scraping position is the position where the scraping paddle 240A contacts and scrapes the sheet so that the rear end of the sheet, which is placed on the processing tray 220 and conveyed in the second conveying direction by the scraping paddle 240A, abuts against the rear end regulating member 290. The height of this scraping position is set according to the basis weight and number of sheets loaded on the processing tray 220. In other words, when there is one sheet on the processing tray 220, the scraping position is the lowest position from the retracted position, and when there are 50 sheets, the scraping position is higher towards the retracted position compared to the case of one sheet.

[0044] In this embodiment, there is a mode in which a stapler 400 is used to staple the sheet bundle on the processing tray 220. In this case, the sheets dropped from the pre-processing roller 212 onto the processing tray 220 are transported in a switchback manner toward the rear end regulating member 290, and center alignment is performed by sandwiching the sheets from both sides with a pair of alignment plates 271A and 271B at that position. However, depending on the width of the sheet, the position where the stapling process is to be performed on the sheet may overlap with the rear end regulating member 290, making corner stapling impossible. Therefore, for sheets of such width, the sheets are shifted one by one in the width direction to the corner stapling position for corner stapling, and then width alignment (this is called shift alignment) is performed to form a sheet bundle at the corner stapling position on the processing tray 220.

[0045] For example, when performing rear corner binding, shift alignment involves shifting the sheet towards the rear of the device (for front corner binding, the sheet is shifted towards the front of the device). In this case, the rear alignment plate 271B waits in the alignment position, and the front alignment plate 271A pushes the edge of the sheet in the width direction to shift the sheet towards the rear, so that the sheet is shifted without being sandwiched between the alignment plates 271A and 271B. Therefore, when shifting and aligning large sheets that are larger than the predetermined size and have a long vertical orientation (the length in the transport direction is longer than the length in the sheet width direction), the alignment plate 271A pushes the side edge of the sheet on the rear end side (the side of the rear end regulating member 290) of the sheet, which is more prone to skew.

[0046] In this embodiment, a large sheet (LDR, B4R, B5R, etc.) with a sheet width of 220 mm to less than 297 mm and a sheet transport length (length in the second transport direction) longer than the sheet width length is referred to as the first sheet. The first sheet is sized so that, when shifted to the rear corner binding position, the rear end of the sheet can contact the frontmost rear end restricting member 290a. In other words, the sheet width length of the first sheet is such that, when shifted to the rear corner binding position, the front edge of the sheet is located further forward than the rear end of the frontmost rear end restricting member 290a (see Figure 19(a)).

[0047] As described above, such a first sheet is prone to skew during shift alignment. Therefore, in this embodiment, during shift alignment of the first sheet, the knurled belt 281 is moved from the scraping position to a first raised position by a first amount of upward movement (for example, a position obtained by rotating the shaft 285 5 degrees clockwise from the state where the knurled belt 281 is in the scraping position), and the first sheet is shifted by the alignment plate 271A while being scraped toward the rear end regulating member 290 with a first scraping force. This suppresses skew when shifting alignment of the first sheet. As described above, the scraping position is changed by the sheets stacked on the processing tray 220, but the first raised position is a position obtained by raising from the changed scraping position by a first amount of upward movement.

[0048] On the other hand, if a sheet with a width narrower than a predetermined size is shift-aligned, the rear end of the sheet will detach from the upstream rear end restricting member 290a in the shift direction of the multiple rear end restricting members 290. In this embodiment, a sheet with a width of 220 mm or less that can be stapled (A4R, LGL, LTRR, A-LTRR, etc.) is referred to as a second sheet. When the second sheet is shifted to the rear corner binding position, its length is such that the front edge of the sheet is located further rear than the rear end of the frontmost rear end restricting member 290a (see Figure 27(a)).

[0049] When shifting and aligning such a second sheet, if the same digging force as the first sheet is used to continue digging the sheet, the rear end of the sheet will come off the rear end restricting member 290a, increasing the contact pressure between the rear end of the sheet and the rear end restricting members 290b and 290c, creating resistance when shifting. If the sheet is pushed only by the alignment plate 271A with the brake applied to the rear end of the sheet in this way, the sheet will skew, and the rear corner of the sheet will come into contact with the stapler 400, making it impossible to position the sheet at the corner binding position, potentially resulting in missing pages.

[0050] Therefore, in this embodiment, when shifting the second sheet, the knurled belt 281 is moved from the gripping position to a second raised position by a second amount of upward movement (for example, a position obtained by rotating the shaft 285 14 degrees clockwise from the state where the knurled belt 281 is in the gripping position), and the second sheet is shifted by the alignment plate 271A with a second gripping force that is weaker than that of the first sheet, or without gripping at all. During shift alignment, the alignment plate 271A presses the second sheet at a position closer to the center of gravity of the sheet compared to the first sheet, so skew is less likely to occur. Therefore, even if the gripping force of the sheet is weak or even if it is not gripped at all during shifting, skew is less likely to occur, and after the shift and width alignment are completed, the knurled belt 281 is moved back to the gripping position and the rear end of the sheet is brought into contact with the rear end regulating members 290b and 290c to position the second sheet at the corner binding position.

[0051] [Discharge roller] The upper discharge roller (upper discharge rotating body) 230A and the lower discharge roller (lower discharge rotating body) 230B constitute a pair of discharge rotating bodies and a discharge section, and transport the sheet, which has been conveyed downstream in the first conveying direction by the pre-processing rollers 211A and 212A, to a point downstream in the first conveying direction from the processing tray 220 for discharge. The upper discharge roller 230A is movable between a clamping position (contact position) in which it clamps the sheet between itself and the lower discharge roller 230B, and a retracted position which is retracted upward from the clamping position, and clamps the sheet between itself and the lower discharge roller 230B in the clamping position. That is, the upper discharge roller 230A functions as a nip member that nips the sheet between itself and the lower discharge roller 230B in the clamping position. The upper discharge roller 230A and the lower discharge roller 230B are each arranged in pairs spaced apart in the width direction of the sheet. In this embodiment, they are arranged inside the width direction of the pair of scraping paddles 240A.

[0052] The upper discharge roller 230A and the lower discharge roller 230B grip a sheet or sheet bundle at the gripping position, and the gripped sheet or sheet bundle is conveyed by, for example, the rotation of the lower discharge roller 230B. The upper discharge roller 230A is a driven roller that rotates in accordance with the rotation of the lower discharge roller 230B, but it may also be driven. That is, in this embodiment, the upper discharge roller 230A is the driven rotating body, and the lower discharge roller 230B is the driving rotation. The upper discharge roller 230A also functions as a nip member that can grip a sheet between itself and the lower discharge roller 230B at the gripping position, but this nip member may be another rotating body such as a belt instead of a roller, or it may be a contact member that contacts the sheet without rotating, such as a lever member.

[0053] Furthermore, the lower discharge roller 230B may be a rotating body other than a roller, such as a belt. If the lower discharge roller 230B as the lower discharge rotating body is an endless belt, for example, this belt is stretched by multiple rollers, and the outer surface of the belt stretched on one of the multiple rollers comes into contact with a nip member such as the upper discharge roller 230A to form a discharge nip portion 230a (see Figure 7(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 the position where the discharge nip portion 230a is formed.

[0054] The upper discharge roller 230A is rotatable around the pivot axis 2301 between the gripping position and the retracted position (separated position). In other words, the upper discharge roller 230A is vertically movable between the gripping position and the retracted position. The upper discharge roller 230A is provided at the tip of the discharge arm 2302, which serves as a support. The pivot axis 2301 is provided coaxially with the aforementioned pivot point 2403 and is located upstream of the pre-processing nip section 211a, which grips the sheet with the pre-processing rollers 211A and 212A, in the first conveying direction, and vertically above the pre-processing nip section 211a. The discharge arm 2302 extends downstream from the pivot axis 2301 in the first conveying direction, and the upper discharge roller 230A is provided at its tip. The pivot shaft 2301 does not necessarily have to be coaxial with the pivot point 2403, but in this embodiment, the pivot shafts of the upper discharge roller 230A and the scraping paddle 240A are coaxial.

[0055] The pivot shaft 2301 is positioned upstream in the first conveying direction from the discharge nip section where the upper discharge roller 230A nips the sheet between itself and the lower discharge roller 230B in the clamping position. Furthermore, in the retracted position, the upper discharge roller 230A is positioned vertically above the pre-processing nip section 211a where it nips the sheet with the pre-processing rollers 211A and 212A, and the pivot shaft 2301 is positioned vertically above the center of the upper discharge roller 230A in the retracted position.

[0056] As described above, the upper discharge roller 230A has a positional relationship with the pivot axis 2301 and the pre-processing nip portion 211a, so when it is in the retracted position, it allows the sheet that has passed the pre-processing nip portion 211a to move toward the loading tray 300. On the other hand, the upper discharge roller 230A moves downward from the retracted position toward the clamping position by rotating counterclockwise around the pivot axis 2301 in Figure 2. When the upper discharge roller 230A moves toward the clamping position, the sheet can be clamped between the upper discharge roller 230A and the lower discharge roller 230B.

[0057] In this embodiment, the lower discharge roller 230A is positioned to protrude slightly upward from the processing tray 220 in the retracted position, and the sheet placed on the processing tray 220 can be gripped by the upper discharge roller 230A and the lower discharge roller 230B in the gripping position simply by moving the upper discharge roller 230A downward. Furthermore, in order to move to the gripping position, the lower discharge roller 230B may move upward, or the upper discharge roller 230A and the lower discharge roller 230B may move toward each other to grip the sheet.

[0058] [Matching part] The alignment section 270A, which functions as a shift section, will be described with reference to Figures 4(a) to 4(c), in addition to Figures 2 and 3. The alignment section 270A moves the sheet in the shift direction by contacting the edge of the sheet that has been conveyed downstream in the first conveying direction by the pre-processing rollers 211A and 212A along the first conveying direction, and moving in the shift direction (width direction) that intersects the first conveying direction. Such an alignment section 270A has a pair of alignment plates 271A and 271B that are arranged to face each other with respect to the shift direction.

[0059] The pair of alignment plates 271A and 271B are positioned further downstream than the downstream end of the first transport direction of the transport path 210A, and move in the width direction to contact the widthwise edge of the sheet, thereby aligning the sheet in the width direction. In this embodiment, they are positioned on both sides in the width direction of the sheet placed on the processing tray 220, and are movable in the width direction. Furthermore, the pair of alignment plates 271A and 271B extend from the upstream side to the downstream side in the first transport direction with respect to the upper discharge roller 230A and the lower discharge roller 230B, respectively. That is, the pair of alignment plates 271A and 271B are positioned to straddle the upper discharge roller 230A and the lower discharge roller 230B with respect to the first transport direction. The configuration of the pair of alignment plates 271A and 271B is the same. The pair of alignment plates 271A and 271B move in the shift direction by the drive of the front (F) alignment plate moving motor MT16 and the rear (R) alignment plate moving motor MT17 (see Figure 12), which serve as the first and second drive units.

[0060] The matching plate 271A is formed such that its vertical width is wider on the downstream side in the first conveying direction. That is, the matching plate 271A has a first plate portion 2701 on the downstream side in the first conveying direction and a second plate portion 2702 formed to be continuous with the first plate portion 2701 on the upstream side in the first conveying direction. The first plate portion 2701, as the first part, has a larger vertical area than the second plate portion 2702 so that it can come into contact with the sheet even if the leading edge of the conveyed sheet is curled upward or downward.

[0061] On the other hand, the second plate portion 2702, as the second part, is shorter in height from the processing tray 220 than the first plate portion 2701, and is shorter in height than the distance between the rear end drop members 250A and 250B, which are located in the guide position described later, and the processing tray 220. In other words, the second plate portion 2702 is formed to have a lower vertical height than the first plate portion 2701 so that it does not interfere with the rear end drop members 250A and 250B even when they are located in the lower position (guide position). Furthermore, the upper edge of the second plate portion 2702 is sloped so that it becomes lower as it is directed upstream in the first conveying direction.

[0062] Furthermore, the first plate portion 2701 is formed to span from the upstream to the downstream side in the first transport direction with respect to the upper discharge roller 230A and the lower discharge roller 230B. This ensures that at least the first plate portion 2701 can contact the sheet even when the sheet is discharged by the switchback-less shift discharge process described later. The second plate portion 2702 is located on the processing tray 220 and is formed continuously with respect to the first plate portion 2701 in the first transport direction. This ensures that at least the second plate portion 2702 can contact the sheet placed on the processing tray 220 by the switchback-shift discharge process described later.

[0063] Furthermore, the first plate portion 2701 has a curl-holding portion 2703, as shown in Figures 4(a) to 4(c). The curl-holding portion 2703 is located downstream in the first conveying direction from the discharge nip portion 230a (see Figure 7(b) described later), which is the nip position where the sheet is held between the upper discharge roller 230A and the lower discharge roller 230B, and is also located vertically above the discharge nip portion 230a, and holds down the leading edge of the sheet that has curled upward. In this embodiment, the curl-holding portion 2703 is a projection that protrudes inward in the width direction from the upper end of the first plate portion 2701 (the side that contacts the sheet, the right side in Figure 4(b)), and the leading edge of the curled sheet in the width direction contacts it, thereby holding down the leading edge of the sheet. Furthermore, a grooved portion 2705 is provided below the curl-holding portion 2703, and depending on the curl state, the widthwise edge of the sheet can catch on this grooved portion 2705, making it possible to hold down the tip of the curled sheet.

[0064] [Loading tray] As described above, the loading tray 300, which serves as the loading section, loads the sheets discharged by the upper discharge roller 230A and the lower discharge roller 230B. The loading tray 300 is located downstream of the processing tray 220 in the first transport direction and is provided so as to be able to move up and down vertically. Furthermore, the loading tray 300 is inclined with respect to the horizontal plane such that the upstream side in the first transport direction is lower than the downstream side. Such a loading tray 300 is supported so as to be able to move vertically along rails arranged in the vertical direction, and moves up and down by driving the loading tray lifting motor MT20 (Figure 12), which serves as the lifting means.

[0065] At the upstream end of the loading tray 300 in the first transport direction, there is a vertical surface 310a, which serves as a loading-side restricting means for restricting the upstream end (rear end) of the sheet or sheet bundle loaded on the loading tray 300 in the first transport direction, and a rear end retainer 310b for holding down the rear end of the sheet that is in contact with the vertical surface 310a. The rear end retainer 310b is inclined towards the downstream side in the first transport direction as it extends upward, so that even if the rear end of the sheet is curled upward, it can be held down by this rear end retainer 310b.

[0066] Furthermore, a discharge sheet scraping paddle 320A is provided coaxially with the rotation axis of the lower discharge roller 230B. Note that the rotation axis 3201 (Figure 2) of the discharge sheet scraping paddle 320A does not necessarily have to be coaxial with the rotation axis of the lower discharge roller 230B. The rotation axis 3201 of the discharge sheet scraping paddle 320A only needs to be provided in the vertical direction between the discharge nip portion 230a of the upper discharge roller 230A and the lower discharge roller 230B, which are a pair of discharge rotating bodies (see Figure 7(b) described later), and the vertical surface 310a, which is a loading side abutment portion provided on the upstream side of the loading tray 300 in the first transport direction. In this embodiment, as shown in Figure 2, the rotation axis 3201 of the discharge sheet scraping paddle 320A is positioned in the vertical direction between the downstream end of the processing tray 220 in the first transport direction and the upper end of the vertical surface 310a.

[0067] The loading tray 300 can be raised and lowered by the loading tray lifting motor MT20 between a first loading position and a second loading position lower than the first loading position. The second loading position is the position where the loading tray 300, which was descending when a sheet is discharged onto the loading tray 300, switches to an upward movement. When a sheet is discharged, the loading tray 300 moves up and down, and the discharged sheet scraping paddle 320A rotates, transporting (scooping in) the sheet on the loading tray 300 in a third transport direction, with the upstream edge in the first transport direction facing the vertical surface 310a. The upper surface of the sheet on the loading tray 300, or a sheet bundle consisting of multiple sheets, is then pressed down by the discharged sheet scraping paddle 320A.

[0068] [Drive system configuration for each part] Next, the drive configuration of the upper discharge roller 230A, the scraping paddle 240A, and the rear end drop members 250A and 250B will be explained using Figures 5(a) to 10(c). In this embodiment, the upper discharge roller 230A, the scraping paddle 240A, and the rear end drop members 250A and 250B are configured to interlock with each other. As shown in Figure 5(a), this drive configuration 600 includes a processing motor 610 (MT12, Figure 12) as a drive source, a drive transmission mechanism 611, a rotating shaft 612, and a cam mechanism 613. The processing motor 610 can rotate in both forward and reverse directions, 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 that transmits drive by a belt, may also be used.

[0069] The rotating shaft 612 is positioned above the upper discharge roller 230A, the scraping paddle 240A, and the rear end drop members 250A and 250B, extending in the width direction. The rotation of the rotating shaft 612 operates the cam mechanism 613. The cam mechanism 613 has a first cam member 620 and a second cam member 630 that rotate together with the rotating shaft 612. The first cam member 620 is positioned between the pair of upper discharge rollers 230A and operates the upper discharge rollers 230A. The second cam member 630 is provided adjacent to each of the pair of scraping paddles 240A and operates the scraping paddles 240A and the rear end drop members 250A and 250B.

[0070] As shown in Figure 6(a), the first cam member 620 has a groove 621 formed on its inner side, into which a projection 2303 provided on the discharge arm 2302 of the upper discharge roller 230A can enter. The outer circumferential surface of the groove 621, i.e., the inner circumferential surface of the first cam member 620, is the inner cam surface 622. The inner cam surface 622 is a cam surface whose distance from the rotation center of the rotation shaft 612 differs depending on the phase in the rotation direction. The outer circumferential surface of the first cam member 620 is the 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 differs depending on the phase in the rotation direction.

[0071] The discharge arm 2302 of the upper discharge roller 230A has a contact portion 2304 that can contact the outer cam surface 623 of the first cam member 620, in addition to the projection 2303 described above. By rotating together with the rotation shaft 612, the first cam member 620 changes the contact position (phase) between the inner cam surface 622 and the projection 2303, or separates them, and changes the contact position (phase) between the outer cam surface 623 and the contact portion 2304, or separates them, thereby rotating the upper discharge roller 230A around the rotation shaft 2301 from the clamping position to the retracted position, as will be described later.

[0072] As shown in Figure 6(b), the second cam member 630 has a groove 631 formed on its inner side, into which the first projection 2404 provided on the paddle arm 2402 of the scraping paddle 240A can enter. The outer circumferential surface of the groove 631, i.e., the inner circumferential surface of the second cam member 630, is the inner cam surface 632. The inner cam surface 632 is a cam surface whose distance from the rotation center of the rotation axis 612 differs depending on the phase in the rotation direction. By rotating together with the rotation axis 612, the second cam member 630 changes the contact position (phase) between the inner cam surface 632 and the first projection 2404, thereby rotating the scraping paddle 240A around the pivot point 2403 from the return position to the upward retracted position, as will be described later.

[0073] Furthermore, the support portion 2406, which pivots together with the paddle arm 2402 of the scraping paddle 240A around the pivot point 2403 and supports the end of the rotation axis 2401a of the paddle portion 2401, is provided with a second projection 2405 that can enter into an engaging recess 2502 formed in the rear end drop members 250A and 250B, as shown in Figure 6(c). The engaging recess 2502 contacts or separates from the second projection 2405, and in conjunction with the rotation of the scraping paddle 240A, it rotates the rear end drop members 250A and 250B around the rotation axis 2501 from an upper position to a lower position. The driving of the upper discharge roller 230A, scraping paddle 240A, and rear end drop members 250A and 250B will be described in detail below.

[0074] [Home position] First, Figures 5(a) to 6(c) show the home positions (HP) of the upper discharge roller 230A, the scraping paddle 240A, and the rear end drop members 250A and 250B. In the home positions, as shown in Figures 5(a) and (b), the upper discharge roller 230A is in the retracted position, the scraping paddle 240A is in the upward retracted position, and the rear end drop members 250A and 250B are in the upward position.

[0075] In this state, as shown in Figure 6(a), the projection 2303 of the upper discharge roller 230A contacts the inner cam surface 622 of the first cam member 620 at a position close to the center of the rotation axis 612, thereby supporting the upper discharge roller 230A on the first cam member 620.

[0076] Furthermore, as shown in Figure 6(b), the scraping paddle 240A is supported by the second cam member 630 because the first projection 2404 of the scraping paddle 240A contacts the inner cam surface 632 of the second cam member 630 at a position close to the center of the rotation axis 612.

[0077] Furthermore, as shown in Figure 6(c), the engaging recesses 2502 of the rear end drop members 250A and 250B abut against the second projection 2405 of the scraping paddle 240A, thereby supporting the rear end drop members 250A and 250B on the scraping paddle 240A via the second projection 2405.

[0078] [Lower discharge roller] Next, the operation of moving the upper discharge roller 230A from the home position (retracted position) to the clamping position will be explained using Figures 7(a) to 8(c). In order to lower the upper discharge roller 230A from the home position, the processing motor 610 is driven to rotate the rotation shaft 612 in the first direction (counterclockwise in Figures 8(a) and (b)), and the first cam member 620 also rotates in the same direction, causing the projection 2303 to move along the inner cam surface 622. The inner cam surface 622 is formed such that when it rotates counterclockwise from the home position, the distance from the center of the rotation shaft 612 increases. As a result, this operation causes the upper discharge roller 230A to descend.

[0079] Next, when the upper discharge roller 230A moves to the clamping position and contacts the lower discharge roller 230B, as shown in Figure 8(a), the inner cam surface 622 and projection 2303 of the first cam member 620 separate, 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 way, the upper discharge roller 230A is pressurized toward the lower discharge roller 230B, thereby applying a predetermined nip pressure between these rollers.

[0080] In this case, the second cam member 630 also rotates together with the rotation shaft 612, but as shown in Figure 8(b), the distance from the center of the rotation shaft 612 to the position where the inner cam surface 632 contacts the first projection 2404 is approximately the same as the distance in the home position. Therefore, even when the second cam member 630 rotates, the scraping paddle 240A is maintained in the home position. Because the scraping paddle 240A is maintained in the home position, the rear end drop members 250A and 250B are also maintained in the home position, as shown in Figure 8(c). That is, in this state, as shown in Figure 7(b), the upper discharge roller 230A moves to the clamping position, but the scraping paddle 240A and the rear end drop members 250A and 250B are maintained in the home position.

[0081] When raising the upper discharge roller 230A, the motor 610 is driven to rotate the rotating shaft 612 in a second direction opposite to the first direction (clockwise in Figures 8(a) and (b)). As a result, the first cam member 620 rotates in the same direction as the rotating shaft 612, causing the projection 2303 to move along the inner cam surface 622, and the upper discharge roller 230A rises. Then it returns to the home position shown in Figure 6(a).

[0082] Here, when the scraping paddle 240A and the rear end drop members 250A and 250B return from the state shown in Figures 8(b) and (c) to the state shown in Figures 6(b) and (c), the first projection 2404 moves along the inner cam surface 632 of the second cam member 630. However, the inner cam surface 632 is formed such that the distance from the center of the rotation axis 612 to the position where the inner cam surface 632 contacts the first projection 2404 does not change. Therefore, the scraping paddle 240A remains in its home position. Because the scraping paddle 240A is maintained in its home position, the rear end drop members 250A and 250B also remain in their home positions.

[0083] [Lowering of the scraping paddle and the rear end drop member] Next, the operation of moving the scraping paddle 240A and the rear end drop members 250A and 250B from the home position (upper retracted position, upper position) to the return position and lower position will be explained using Figures 9(a) to 10(c). In order to lower the scraping paddle 240A and the rear end drop members 250A and 250B from the home position, the motor 610 is driven to rotate the rotation shaft 612 in a second direction opposite to the first direction (clockwise in Figures 10(a) and (b)). As a result, the first cam member 620 also rotates in the same direction, and the projection 2303 moves along the inner cam surface 622. The inner cam surface 622 is formed such that the distance from the center of the rotation shaft 612 does not change significantly even when rotated clockwise from the home position. For this reason, as shown in Figure 10(a), the upper discharge roller 230A is maintained in the home position.

[0084] Meanwhile, the second cam member 630 also rotates in the same direction as the rotation shaft 612, causing the first projection 2404 to move along the inner cam surface 632. The inner cam surface 632 is formed such that when it rotates clockwise from the home position, its distance from the center of the rotation shaft 612 increases. As a result of this movement, the scraping paddle 240A descends and moves to the return position.

[0085] At this time, the rear end drop members 250A and 250B also descend together with the scraping paddle 240A. In this embodiment, when the rear end drop members 250A and 250B are rotated from an upper position to a lower position, they have a positioning portion 2503 that engages with an engaging portion 200a provided on a part of the upper cover of the sheet processing device 200, as shown in Figures 33(a) and (b) described later, thereby positioning them in the lower position. The positioning portion 2503 is provided so as to protrude further forward from the front end of the front rear end drop member 250A, as shown in Figures 16 and 33(b) described later.

[0086] The engaging portion 200a is formed to protrude downward from a part of the front side of the cover that covers the upper part of the rear end drop members 250A and 250B, and to bend toward the rear. The positioning portion 2503 is an engaged portion provided to be engageable with the engaging portion 200a, and by contacting the engaging portion 200a, it restricts the rear end drop members 250A and 250B from descending any further. The engaging recess 2502 is formed to be separated from the second projection 2405 in this state. Therefore, the rear end drop members 250A and 250B are in a state where their engagement with the scraping paddle 240A is released and they are positioned in a lower position by the positioning portion 2503.

[0087] As a result, even when the scraping paddle 240A reaches the return position, the rear end drop members 250A and 250B are not lowered further due to the engagement between the positioning part 2503 and the engaging part 200a, and are positioned in the lower position. In this state, as shown in Figure 9(b), the scraping paddle 240A and the rear end drop members 250A and 250B move to the return position and the lower position, and the upper discharge roller 230A is positioned in the home position.

[0088] The engagement portion 200a and positioning portion 2053 described above may be omitted. In this case, a separate positioning mechanism may be provided to position the rear end drop members 250A and 250B to a lower position. For example, positioning may be performed by the engagement of the engagement recess 2502 and the second projection 2405 at the lower position.

[0089] When raising the scraping paddle 240A and the rear end drop members 250A and 250B, the motor 610 is driven to rotate the rotating shaft 612 in the first direction (counterclockwise in Figures 10(a) and (b)). As a result, the second cam member 630 rotates in the same direction as the rotating shaft 612, causing the first projection 2404 to move along the inner cam surface 632, and the scraping paddle 240A rises. At this time, slightly delayed from the start of the scraping paddle 240A's rise, the second projection 2405 re-engages with the engagement recess 2052, and this engagement causes the rear end drop members 250A and 250B to also rise. In other words, the scraping paddle 240A can rise independently by the amount of the gap between the second projection 2405, which is in the return position of the scraping paddle 240A, and the portion of the engaging recess 2502 located above the second projection 2405. When the scraping paddle 240A rises by this amount, the rear end drop members 250A and 250B are still in the lower position. Then, when the second projection 2405 rises by this amount and engages with the engaging recess 2502, the rear end drop members 250A and 250B begin to rise with a delay compared to the scraping paddle 240A. As a result, the scraping paddle 240A and the rear end drop members 250A and 250B return to the home positions shown in Figures 5(a) to 6(c).

[0090] Here, when the upper discharge roller 230A returns from the state shown in Figure 10(a) to the state shown in Figure 6(a), the projection 2303 moves along the inner cam surface 622 of the first cam member 620. However, the inner cam surface 622 is formed such that the distance from the center of the rotation axis 612 to the position where the inner cam surface 622 contacts the projection 2303 does not change. Therefore, the upper discharge roller 230A remains in its home position.

[0091] In this embodiment, when the rotating shaft 612 is rotated counterclockwise from the home position as shown in Figures 6(a) to 6(c), the upper discharge roller 230A descends, and the scraping paddle 240A and the rear end dropping members 250A and 250B are maintained in the home position. On the other hand, when the rotating shaft 612 is rotated clockwise from the home position as shown in Figures 6(a) to 6(c), the upper discharge roller 230A is maintained in the home position, and the scraping paddle 240A and the rear end dropping members 250A and 250B descend.

[0092] Furthermore, when the upper discharge roller 230A is in the clamping position shown in Figure 8(a), and the rotation shaft 612 is rotated clockwise as shown in Figures 8(a) to 8(c), the upper discharge roller 230A rises, and the scraping paddle 240A and the rear end dropping members 250A and 250B are maintained in the home position. On the other hand, when the scraping paddle 240A and the rear end dropping members 250A and 250B are in the return position and the lower position, and the rotation shaft 612 is rotated counterclockwise as shown in Figures 10(a) to 10(c), the upper discharge roller 230A is maintained in the home position, and the scraping paddle 240A and the rear end dropping members 250A and 250B rise.

[0093] Figure 12 shows the relationship between each motor and each component. The columns in Figure 12, from left to right, show the number, motor name, drive component, operation, direction of operation in forward rotation, and direction of operation in reverse rotation. In Figure 12, the processing motor MT12 is the processing motor 610 mentioned above. As is clear from Figure 12, 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 scraping paddle 240A, and the return member 280.

[0094] Furthermore, the motor MT12 controls the raising and lowering of the scraping paddle 240A, the rear end drop members 250A and 250B, and the upper discharge roller (nip member) 230A during processing. In this embodiment, in addition to the above, a return lifting motor MT13 for raising and lowering the return member 280, a discharge roller motor MT14 for driving the lower discharge roller 230B, a scraping motor (sheet pressing motor) MT15 for driving the discharge sheet scraping paddle (sheet pressing (bundle pressing) paddle) 320A, an F-side alignment plate moving motor MT16 for moving the front alignment plate 271A in the width direction (lateral movement), an R-side alignment plate moving motor MT17 for moving the rear alignment plate 271A in the width direction (lateral movement), 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, a loading tray lifting motor MT20 for raising and lowering the loading tray 300, and a stapleless STP motor MT21 for driving the stapleless stapling unit 500 to staple the sheet bundle.

[0095] [Control configuration for sheet processing device] The control configuration of the sheet processing device 200 will be explained using Figure 13. Figure 13 is a block diagram showing the motors and sensors of the sheet processing device 200. The signals from each of these sensors are input to the control unit 203, which acts as a control means, and each motor is controlled by the control unit 203. The control unit 203 is connected to the control unit 1003 of the image forming apparatus 100 in a communicative manner, and controls the entire sheet processing device 200 based on the mode (job) information received from the control unit 1003 of the image forming apparatus 100.

[0096] Such a control unit 203 includes a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The CPU controls each part while reading programs corresponding to control procedures stored in ROM. The RAM stores working data and input data, and the CPU performs control by referring to the data stored in RAM based on the aforementioned programs, etc.

[0097] Each motor shown in Figure 13 is as described above. On the other hand, each sensor will be explained with reference to Figure 2. First, the inlet sensor SN11 is installed on the transport path 210A and is for detecting the leading edge of the sheet being transported on the transport path 210A. The processing HP sensor SN12 detects the home positions of the scraping paddle 240A, the rear end drop members 250A and 250B, and the upper discharge roller (nip member) 230A. The return lifting HP sensor SN13 detects the home position of the return member 280 (the position after it has been moved away from the processing tray 220). 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 scraping paddle 320A.

[0098] The F-side alignment plate HP sensor SN16 and the R-side alignment plate HP sensor SN17 detect that the front alignment plate 271A and the rear alignment plate 271A, respectively, are in a position (home position) separated in the width direction from the sheet 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 topmost sheet placed on the loading tray 300. The loading tray encoder sensor SN20 detects the vertical position of the loading tray 300. The loading tray lower limit position detection sensor SN21 detects the lower limit position of the loading tray 300. The control unit 203 performs the following controls based on the signals (outputs) from each of these sensors.

[0099] Next, the control flow for each mode of this embodiment will be briefly explained with reference to Figure 15. The control unit 203 determines whether the discharge mode received from the image forming apparatus 100 is straight discharge mode, shift mode, or staple mode (S1). In the case of straight discharge mode, the control unit 203 drives the transport roller pair 213, the pre-processing roller pair 211A, 212A, and the discharge roller pair 230A, 230B to discharge the sheets received from the image forming apparatus 100 one by one into the loading tray 300 (S2).

[0100] If the discharge mode is shift mode, the control unit 203 checks the sheet size information received from the image forming apparatus 100 (S3), and if it is a small size, it determines whether or not it is in productivity priority mode (S4). In productivity priority mode, the control unit 203 drives the transport roller pair 213, the pre-processing roller pair 211A, 212A, the pair of alignment plates 271A, 271B, and the discharge roller pair 230A, 230B to discharge the sheets received from the image forming apparatus 100 onto the loading tray 300 one by one while shifting them (S5). In this embodiment, this shift discharge process is called switchbackless shift discharge process.

[0101] By changing the shift direction between the first and second sheet bundles in this switchbackless shift discharge process, multiple unbound sheet bundles can be formed on the loading tray 300, sorted by sheet bundle, as shown in Figure 37.

[0102] If the sheet size is large in S3, or if the sheet is small in S4 but not in productivity priority mode, the control unit 203 repeatedly performs switchback transport and shifting and aligning of the sheets one by one using a pair of alignment plates 271A and 271B to form a stack of shifted sheets on the processing tray 220 (S6-1). The stack of shifted sheets formed on the processing tray 220 is then discharged to the loading tray 300 using a pair of discharge rollers 230A and 230B (S6-2). In this embodiment, this shift discharge process is called the switchback shift discharge process.

[0103] By changing the shift direction for the first and second bundles of sheets in this switchback shift discharge process, multiple unbound bundles of sheets can be formed on the loading tray 300, sorted by bundle, as shown in Figure 37.

[0104] Furthermore, when the discharge mode is stapling mode (S1), the control unit 203 forms a sheet bundle on the processing tray 220 (S7), performs stapling on the sheet bundle formed on the processing tray 220 using the stapling unit 400 or the stapleless stapling unit 500 (S8), and discharges the stapled sheet bundle to the loading tray 300 using the discharge roller pair 230A, 230B (S9).

[0105] Here, the sheet bundle formation routine in stapling mode, which is controlled by the control unit 203, will be explained using the flowchart in Figure 16 and the operation diagrams in Figures 17 to 32. First, the sheet is transported by the pre-processing roller 212A (St1) (Figure 17(a)(b)), while the knurled belt 281 is lowered to the scraping position (St2). Once the sheet is dropped into the processing tray 220, the sheet is transported in a switchback manner by the scraping paddle 240A and the knurled belt 281, and the rear end of the sheet is brought against the rear end regulating member 290 (St3) (Figure 18(a)(b)). At this point, it is determined whether the stapling process for this job is corner stapling or two-point stapling (St4), and if it is two-point stapling, the knurled belt 281 is moved to the first raised position (St5), and the sheet is center-aligned with the alignment plates 271A and 271B (St6). Note that the determination itself does not necessarily have to be made at this timing.

[0106] Subsequently, the knurled belt 281 is moved back to the grabbing position to abut the rear end of the sheet against the rear end regulating member 290 (St7). Then, it is determined whether this sheet is the final sheet or not (St8). If it is not the final sheet, the process returns to St1 to accept the next sheet. If it is the final sheet, the sheet bundle formation routine is terminated.

[0107] In St4, if corner binding is used, it is determined whether the sheet width is longer than a predetermined length (297 mm or more in this embodiment, specifically A4 landscape, A3, etc.) or if it is a third sheet (St9). If it is a third sheet, even if corner binding is used, there is no need to shift the sheet in the width direction, so center alignment is performed in the same way as with two-point binding (St5, St6). The following explanation is omitted as it is the same as with two-point binding.

[0108] If the sheet width is shorter than a predetermined length in St9, it is determined whether the sheet is the second sheet or not (St10). If it is the first sheet ShL1, the knurled belt 281 is moved to the first raised position (St11), and shift alignment is performed with the alignment plate 271 (St13) (Figure 19(a)(b)). After that, the knurled belt 281 is moved to the scraping position to abut the rear end of sheet ShL1 against the rear end regulating member 290 (St7) (Figure 20(a)(b)). If this sheet is not the final sheet and there is a next sheet (St8), the next sheet ShL2 is received with the knurled belt 281 in the scraping position (St1). This prevents the first sheet ShL1 from shifting in the transport direction even if the leading edge of the second sheet ShL2 comes into contact with the first sheet ShL1 (Figure 20(b)).

[0109] Once the rear end of the second sheet ShL2 has passed the pre-processing rollers 211A and 212A, the scraping paddle 240A and the knurled belt 281 are moved (maintained) in the scraping position (St2), and the sheet ShL2 is conveyed in a switchback manner (St3) (Figure 21(a)(b)). Since this sheet is also the first sheet to be corner-bound (St4, St9, St10), the knurled belt 281 is moved to the first raised position (St11) and shift alignment is performed (St13) (Figure 22(a)(b)). After that, the knurled belt 281 is moved to the scraping position and the sheet ShL2 is again brought against the rear end regulating member 290 (St7) (Figure 23(a)(b)).

[0110] The above process is repeated until the last sheet is completed, and once the shift alignment and re-scooping are finished for the last sheet and the sheet bundle SB is formed at the corner binding position on the processing tray 220, the sheet bundle formation routine is terminated, corner binding is performed on the sheet bundle SB (S8 in Figure 15), the knurled belt 281 is moved to the retracted position and the sheet bundle SB is discharged to the loading tray 300 by the discharge roller pair 230A and 230B (Figure 24(a)(b)).

[0111] On the other hand, if the sheet is the second sheet, first the sheet Sh1 is transported by the pre-processing roller 212A (St1) (Figure 25(a)(b)), the scraping paddle 240A and the knurled belt 281 are moved to the scraping position (St2), and the sheet is transported in a switchback manner, causing the rear end of the sheet to abut against the rear end regulating member 290 (St3) (Figure 26(a)(b)). If the sheet in question is a sheet to be corner-bound (St4), is narrower than a predetermined width (St9), and is the second sheet (St10), the knurled belt 281 is moved to the second raised position (St12), and shift alignment is performed (St13) (Figure 27(a)(b)). After that, the knurled belt 281 is moved to the scraping position and the sheet Sh1 is abutted against the rear end regulating member 290 again (St7) (Figure 28(a)(b)).

[0112] If this sheet is not the final sheet and there is a next sheet (St8), the knurled belt 281 accepts the next sheet Sh2 while maintaining its gripping position (St1). This prevents the first sheet Sh1 from shifting in the transport direction even when the leading edge of the second sheet Sh2 comes into contact with it (Figure 28(b)).

[0113] Once the rear end of the second sheet Sh2 has passed the pre-processing rollers 211A and 212A, the scraping paddle 240A and the knurled belt 281 are moved (maintained) in the scraping position (St2), and the sheet Sh2 is transported in a switchback manner (St3) (Figure 29(a)(b)). Since this sheet is also the second sheet to be corner-bound (St4, St9, St10), the knurled belt 281 is moved to the second raised position (St12), and shift alignment is performed (St13) (Figure 30(a)(b)). After that, the knurled belt 281 is moved to the scraping position, and the sheet Sh2 is brought against the rear end regulating member 290 again (St7) (Figure 31(a)(b)).

[0114] The above process is repeated until the last sheet is completed, and once the shift alignment and re-scooping are finished for the last sheet and the sheet bundle SB is formed at the corner binding position on the processing tray 220, the sheet bundle formation routine is terminated, corner binding is performed on the sheet bundle SB (S8 in Figure 15), the knurled belt 281 is moved to the retracted position and the sheet bundle SB is discharged to the loading tray 300 by the discharge roller pair 230A and 230B (Figure 32(a)(b)).

[0115] As described above, when performing shift alignment, skew during sheet shifting can be suppressed by adjusting the gripping force by the knurled belt 281 depending on whether it is the first or second sheet. Note that for sheets that are neither the first nor the second sheet (e.g., LTR, B5 landscape, etc.), the knurled belt 281 can be in either the first or second raised position. For example, even if the sheet is shifted with a weak gripping force or zero gripping force (away from the sheet) in the second raised position, the sheet can be aligned and positioned at the corner binding position by gripping it with the knurled belt 281 after shift alignment has been moved to the gripping position. However, since minimizing skew during shifting shortens the time required for re-gripping, in this embodiment, the sheet is shifted with the knurled belt 281 moved to the first raised position. Note that the knurled belt 281 may also be moved to a third raised position different from the first and second raised positions (e.g., between the first and second raised positions).

[0116] In the embodiment described above, the scraping force is changed by changing the raised position of the knurled belt 281 according to the seat size when shifting the seat, but a different component from the knurled belt 281, such as a sponge roller, may also be used. Alternatively, the scraping force may be changed by changing the amount of rotation or rotational speed without changing the position of the knurled belt 281.

[0117] Furthermore, although the above-described embodiment explained the operation during shift alignment when performing corner binding on a sheet bundle, it can also be applied to shift alignment when performing switchback shift ejection.

[0118] Furthermore, although the stapling mode described above shows a method of performing stapling using a staple unit 400, stapling may also be performed using a stapleless stapling unit 500. In that case, after forming a sheet bundle SB on the processing tray 220, the sheet bundle SB is moved to the rear side by a pair of alignment plates 271A and 271B, stapling is performed on the sheet bundle SB positioned at the stapling position of the stapleless stapling unit 500, and the stapled sheet bundle SB is discharged to the loading tray 300 by the upper discharge roller 230A and the lower discharge roller 230B.

[0119] The operation of the switchbackless shift discharge process will be explained below using Figures 33 to 36. Figure 33 shows the state in which the sheet S is conveyed by the pre-processing roller pair 211A and 212A, and the leading edge of the sheet S has passed between the discharge roller pair 230A and 230B in a separated position. Figure 33(b) shows the state in which the upper discharge roller 230A has moved slightly from its furthest separated position toward the lower discharge roller 230B. Figure 34 shows the state in which the rear end of the sheet S has passed the pre-processing roller pair 211A and 212A. In this state, both ends of the sheet S are sandwiched between the pair of alignment plates 271A and 271B in order to move the sheet S in the shift direction.

[0120] Figure 35 shows the state in which the sheet S is shifted in the shift direction (towards the front in Figure 35(a), but it may also be shifted towards the rear) using a pair of alignment plates 271A and 271B. This causes the sheet S to move in the shift direction. Then, the pair of alignment plates 271A and 271B are retracted from both ends of the sheet S, the upper discharge roller 230A is moved to the nip position to grip the sheet S, and the lower discharge roller 230B is rotated in the discharge direction to discharge the sheet S onto the loading tray 300 (Figure 36). After the discharged sheet S is scraped in by the discharge sheet scraping paddle 320A, the top surface of the sheet S is pressed down.

[0121] By repeating the above operation until the last sheet of the sheet bundle is completed, the first unbound sheet bundle is formed on the front side of the loading tray 300. When forming the next sheet bundle on the loading tray 300, the shift direction is changed to the rear side, so that the second unbound sheet bundle is formed on top of the first unbound sheet bundle and on the rear side (see Figure 37).

[0122] In this switchbackless shift discharge process, the lower discharge roller 230B is not rotated in the discharge direction at the time the sheet S passes the pre-processing roller pair 211A and 212A. When the sheet S, having passed the pre-processing roller pair 211A and 212A, contacts the discharge roller pair 230A and 230B, a brake is applied to prevent the sheet S from flying too far in the discharge direction. This allows the sheet S to be sandwiched between the pair of alignment plates 271A and 271B at a position close to its center of gravity, thereby suppressing the skew of the sheet S during shifting.

[0123] In other words, in this embodiment, when forming a sheet bundle on the processing tray 220 (staple mode or switchback shift discharge mode), the lower discharge roller 230B is rotated in the discharge direction at the timing when the rear end of the first sheet Sh1 passes the pre-processing roller pair 211A and 212A. In the switchbackless shift discharge mode, the lower discharge roller 230B is not rotated in the discharge direction at the timing when the rear end of the sheet passes the pre-processing roller pair 211A and 212A.

[0124] In the above-described embodiment, the sheet processing apparatus 200 is arranged within the internal space 130 of the image forming apparatus 100. However, the sheet processing apparatus of the present invention may be configured, for example, to be mounted on the side of the image forming apparatus. Furthermore, the sheet processing apparatus may be controlled by a control unit 1003 provided in the image forming apparatus. That is, the control unit may be located within the sheet processing apparatus or within the image forming apparatus, as long as it is possible to control the sheet processing apparatus within the image forming system. [Explanation of Symbols]

[0125] 100...Image forming apparatus 103...Image Forming Unit 200-sheet processing device 203... Control Unit 210A... Transport path 211...1st Transport Section 211A, 212A... Pre-processing rollers (conveyor rollers) 220... Processing tray (mounting section) 221... Mounting surface 222...Slope surface 230A... Upper discharge roller (discharge section) 230B... Lower discharge roller (discharge section) 240A... Scooping paddle (second conveying section) 250A, 250B... Rear end drop member (sheet drop section) 271A...Matching plate (movable member) 280...Return parts 281... Knurled belt 290...Rear end restricting member (butt section) 300...Loading tray (loading section) 400 staple unit (stapler) 500... Stapleless stapling unit (stapleless stapling section) 1000...Image forming system

Claims

1. A first conveying unit that conveys the sheet in a first conveying direction, A mounting section for placing the sheet transported by the first transport section, The abutting portion against which the upstream edge of the sheet on the mounting portion in the first transport direction abuts, A second conveying unit that conveys the sheet in a second conveying direction, such that the upstream edge of the sheet on the mounting unit in the first conveying direction is toward the abutment unit, With respect to the width direction of the sheet intersecting the first transport direction, a first alignment plate and a second alignment plate are provided, which are positioned on both sides of the sheet abutting against the abutting portion and which contact both end edges of the sheet in the width direction abutting against the abutting portion to perform alignment processing on the sheet in the width direction, A binding processing unit that performs a binding process on a sheet bundle consisting of multiple sheets formed on the aforementioned mounting unit after the alignment process has been performed, A stacking section for stacking the sheet bundles that have undergone the binding process, A discharge unit for discharging the sheet bundle to the loading section, The system comprises the second transport unit, the first alignment plate, and a control unit that controls the second alignment plate and the binding processing unit, Multiple abutment portions are provided in the width direction. When performing corner binding on the corner portion of the sheet bundle, the control unit moves to the second alignment plate side, which is in a more aligned position than the abutment portion in the width direction, and with the second alignment plate waiting in the aligned position, it performs shift alignment to align the sheet bundle by repeatedly shifting the sheet placed on the aforementioned placement portion in the shift direction toward the second alignment plate using the first alignment plate and then aligning it, and can then perform corner binding on the shift-aligned sheet bundle. When shifting a first sheet in the shifted state in which the edge of the sheet on the first alignment plate side is located upstream in the shift direction of the shift direction of the abutment member furthest upstream in the shift direction, and the length in the second transport direction is longer than the length of the sheet in the width direction, the first alignment plate shifts the sheet in the shift direction while the second transport unit applies a force toward the abutment portion to the sheet with the first transport force, When shift-aligning a second sheet in the shift-aligned state, where the edge of the sheet on the first alignment plate side is located downstream in the shift direction of the abutment member furthest upstream in the shift direction, the first alignment plate shifts the sheet in the shift direction while applying a force toward the abutment member to the sheet with a second conveying force weaker than the first conveying force using the second conveying unit. A sheet processing apparatus characterized by the following:

2. An image forming unit that forms an image on a sheet, A first transport unit transports the sheet on which the image has been formed by the image forming unit in a first transport direction, A mounting section for placing the sheet transported by the first transport section, The abutting portion against which the upstream edge of the sheet on the mounting portion in the first transport direction abuts, A second conveying unit that conveys the sheet in a second conveying direction, such that the upstream edge of the sheet on the mounting unit in the first conveying direction is toward the abutment unit, With respect to the width direction of the sheet intersecting the first transport direction, a first alignment plate and a second alignment plate are provided, which are positioned on both sides of the sheet abutting against the abutting portion and which contact both end edges of the sheet in the width direction abutting against the abutting portion to perform alignment processing on the sheet in the width direction, A binding processing unit that performs a binding process on a sheet bundle consisting of multiple sheets formed on the aforementioned mounting unit after the alignment process has been performed, A stacking section for stacking the sheet bundles that have undergone the binding process, A discharge unit for discharging the sheet bundle to the loading section, The system comprises the second transport unit, the first alignment plate, and a control unit that controls the second alignment plate and the binding processing unit, Multiple abutment portions are provided in the width direction. When performing corner binding on the corner portion of the sheet bundle, the control unit moves to the second alignment plate side, which is in a more aligned position than the abutment portion in the width direction, and with the second alignment plate waiting in the aligned position, it performs shift alignment to align the sheet bundle by repeatedly shifting the sheet placed on the aforementioned placement portion in the shift direction toward the second alignment plate using the first alignment plate and then aligning it, and can then perform corner binding on the shift-aligned sheet bundle. When shifting a first sheet in the shifted state in which the edge of the sheet on the first alignment plate side is located upstream in the shift direction of the shift direction of the abutment member furthest upstream in the shift direction, and the length in the second transport direction is longer than the length of the sheet in the width direction, the first alignment plate shifts the sheet in the shift direction while the second transport unit applies a force toward the abutment portion to the sheet with the first transport force, When shift-aligning a second sheet in the shift-aligned state, where the edge of the sheet on the first alignment plate side is located downstream in the shift direction of the abutment member furthest upstream in the shift direction, the first alignment plate shifts the sheet in the shift direction while applying a force toward the abutment member to the sheet with a second conveying force weaker than the first conveying force using the second conveying unit. An image forming system characterized by the following features.

3. A first conveying unit that conveys the sheet in a first conveying direction, A mounting section for placing the sheet transported by the first transport section, The abutting portion against which the upstream edge of the sheet on the mounting portion in the first transport direction abuts, A second conveying unit that conveys the sheet in a second conveying direction, such that the upstream edge of the sheet on the mounting unit in the first conveying direction is toward the abutment unit, With respect to the width direction of the sheet intersecting the first transport direction, a first alignment plate and a second alignment plate are provided, which are positioned on both sides of the sheet abutting against the abutting portion and which contact both end edges of the sheet in the width direction abutting against the abutting portion to perform alignment processing on the sheet in the width direction, A binding processing unit that performs a binding process on a sheet bundle consisting of multiple sheets formed on the aforementioned mounting unit after the alignment process has been performed, A stacking section for stacking the sheet bundles that have undergone the binding process, A discharge unit for discharging the sheet bundle to the loading section, The system comprises the second transport unit, the first alignment plate, and a control unit that controls the second alignment plate and the binding processing unit, Multiple abutment portions are provided in the width direction. When performing corner binding on the corner portion of the sheet bundle, the control unit moves to the second alignment plate side, which is in a more aligned position than the abutment portion in the width direction, and with the second alignment plate waiting in the aligned position, it performs shift alignment to align the sheet bundle by repeatedly shifting the sheet placed on the aforementioned placement portion in the shift direction toward the second alignment plate using the first alignment plate and then aligning it, and can then perform corner binding on the shift-aligned sheet bundle. When shifting a first sheet in the shifted state in which the edge of the sheet on the first alignment plate side is located upstream in the shift direction from the downstream end of the abutment member furthest upstream in the shift direction, and the length in the second transport direction is longer than the length of the sheet in the width direction, the first alignment plate shifts the sheet in the shift direction while applying a force toward the abutment portion to the sheet by the second transport unit. When shifting a second sheet in the shifted state in which the edge of the sheet on the first alignment plate side is located downstream in the shift direction from the downstream end in the shift direction of the abutment member furthest upstream in the shift direction, the first alignment plate shifts the sheet in the shift direction without applying a force toward the abutment portion by the second transport unit to the sheet. A sheet processing apparatus characterized by the following:

4. An image forming unit that forms an image on a sheet, A first transport unit transports the sheet on which the image has been formed by the image forming unit in a first transport direction, A mounting section for placing the sheet transported by the first transport section, The abutting portion against which the upstream edge of the sheet on the mounting portion in the first transport direction abuts, A second conveying unit that conveys the sheet in a second conveying direction, such that the upstream edge of the sheet on the mounting unit in the first conveying direction is toward the abutment unit, With respect to the width direction of the sheet intersecting the first transport direction, a first alignment plate and a second alignment plate are provided, which are positioned on both sides of the sheet abutting against the abutting portion and which contact both end edges of the sheet in the width direction abutting against the abutting portion to perform alignment processing on the sheet in the width direction, A binding processing unit that performs a binding process on a sheet bundle consisting of multiple sheets formed on the aforementioned mounting unit after the alignment process has been performed, A stacking section for stacking the sheet bundles that have undergone the binding process, A discharge unit for discharging the sheet bundle to the loading section, The system comprises the second transport unit, the first alignment plate, and a control unit that controls the second alignment plate and the binding processing unit, Multiple abutment portions are provided in the width direction. When performing corner binding on the corner portion of the sheet bundle, the control unit moves to the second alignment plate side, which is in a more aligned position than the abutment portion in the width direction, and with the second alignment plate waiting in the aligned position, it performs shift alignment to align the sheet bundle by repeatedly shifting the sheet placed on the aforementioned placement portion in the shift direction toward the second alignment plate using the first alignment plate and then aligning it, and can then perform corner binding on the shift-aligned sheet bundle. When shifting a first sheet in the shifted state in which the edge of the sheet on the first alignment plate side is located upstream in the shift direction from the downstream end of the abutment member furthest upstream in the shift direction, and the length in the second transport direction is longer than the length of the sheet in the width direction, the first alignment plate shifts the sheet in the shift direction while applying a force toward the abutment portion to the sheet by the second transport unit. When shifting a second sheet in the shifted state in which the edge of the sheet on the first alignment plate side is located downstream in the shift direction from the downstream end in the shift direction of the abutment member furthest upstream in the shift direction, the first alignment plate shifts the sheet in the shift direction without applying a force toward the abutment portion by the second transport unit to the sheet. An image forming system characterized by the following features.

Images