Sheet discharge apparatus and image forming system

Abstract

A sheet discharge apparatus and an image forming system are disclosed. The sheet discharge apparatus sets a discharge speed at which sheets are discharged by a discharge device to a first discharge speed when a bundle of sheets includes a first number of sheets, and sets the discharge speed to a second discharge speed lower than the first discharge speed when the bundle of sheets includes a second number of sheets, the second number of sheets being greater than the first number of sheets.

Description

Technical Field

[0001] The present invention relates to a sheet ejection device for ejecting sheet material and an image forming system for forming images on sheet material. Background Technology

[0002] Sheet processing equipment (also known as sorters) has been developed to perform processes such as sorting, binding, and alignment on sheets on which images have been formed, as options for image forming apparatuses such as electrophotographic copiers and laser beam printers. Some sheet processing equipment is configured such that when processing multiple bundles of sheets consecutively, the sheet processing equipment temporarily stops receiving sheets from the image forming apparatus to wait for the previous bundles to finish processing. In this case, the productivity (output) of the image forming system decreases.

[0003] Therefore, a method has been proposed in which sheets received from an image forming apparatus are stacked in a sheet processing apparatus during sheet bundle processing to temporarily hold (buffer) the sheets, and after the sheet bundle processing is completed, the sheets are placed on a processing tray as a sheet bundle. Japanese Patent Publication No. 06-099070 describes a configuration in which two transport paths branching inside a sorter are used to hold the sheets received from the image forming apparatus, and the two sheets are overlapped and stacked on a processing tray.

[0004] However, if the sheet conveying speed is increased to further improve the productivity of the image forming system, the sheet is discharged from the image forming apparatus or sheet handling equipment at high speed. Therefore, the placement of the sheet discharged to a discharge destination such as a discharge tray may not be the same. Summary of the Invention

[0005] According to one aspect of the present invention, a sheet discharge device includes: a first stacking member disposed outside a device body; a first conveying device deployed in the device body in a first conveying path extending toward the first stacking member, wherein the first conveying device conveys sheets to the first stacking member; a discharge device configured to receive sheets conveyed by the first conveying device and discharge the sheets to the first stacking member, wherein the discharge device discharges multiple sheets conveyed from the first conveying device in the form of sheet bundles; a sheet processing device configured to receive sheets not discharged by the discharge device and process the received sheets; a second stacking member disposed outside the device body, wherein sheets processed by the sheet processing device are stacked on the second stacking member; and a controller configured to control the first conveying device and the discharge device to perform a bundle discharge operation for discharging the sheet bundles from the discharge device onto the first stacking member. The controller sets the discharge speed of the sheet discharge device to a first discharge speed when the sheet bundle includes a first number of sheets, and sets the discharge speed to a second discharge speed lower than the first discharge speed when the sheet bundle includes a second number of sheets, wherein the second number of sheets is greater than the first number of sheets.

[0006] Other features of the invention will become clear from the following description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of an image forming system according to an embodiment of the present disclosure.

[0008] Figure 2 This is a cross-sectional view of the overlay processing unit according to an embodiment.

[0009] Figure 3 This is a hardware configuration diagram of an image forming system according to an embodiment.

[0010] Figure 4 This is a functional block diagram of an image forming system according to an embodiment.

[0011] Figures 5A to 5G The illustration shows the operation performed by the overlay processing unit according to an embodiment.

[0012] Figure 6A and Figure 6B This is a flowchart illustrating a control example of the overlay processing unit according to an embodiment.

[0013] Figures 7A to 7CThe illustration shows a method for controlling the amount of protrusion between sheets by using an overlay processing unit according to an embodiment.

[0014] Figure 8 The illustration shows different discharge trajectories of the sheet bundle due to different discharge speeds according to the embodiments.

[0015] Figure 9A The diagram illustrates the discharge trajectory when the discharge speed is set to constant, regardless of the number of sheets in the bundle; and Figure 9B The diagram illustrates the discharge trajectory when the discharge speed is varied according to the number of sheets in the bundle.

[0016] Figure 10A and Figure 10B The diagram illustrates the differences in discharge trajectories caused by differences in basis weight.

[0017] Figure 11A and Figure 11B The diagram illustrates the direction of the sheet's curl. Detailed Implementation

[0018] Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

[0019] Figure 1 This is a schematic diagram of the image forming system 1S according to this embodiment, viewed from the front. The image forming system 1S includes an image forming apparatus 1 that forms an image on a sheet, a sheet processing apparatus 4 that processes the sheet having the image formed by the image forming apparatus 1 thereon, a relay unit 14 that transports the sheet from the image forming apparatus 1 to the sheet processing apparatus 4, and an image reading device 2. Various sheets (printing media) of different sizes and materials can be used. Examples of sheets include paper such as plain paper and thick paper, surface-treated sheet materials such as plastic film, fabric, and coated paper, and sheet materials of special shapes such as envelopes and index paper. The operations performed by each of the devices constituting the image forming system 1S have been briefly described, and the operations performed by the sheet processing apparatus 4 are described in detail below.

[0020] Image forming apparatus 1 includes an electrophotographic image forming unit 8 for forming images and a feeding device 6 for feeding sheets one by one into the image forming unit 8. The image forming unit 8 is integrally housed a photosensitive drum 9, which serves as an image carrier (electrophotographic photosensitive component), and a charging device and a developing device for performing electrophotographic processing by acting on the photosensitive drum 9. A scanner unit 15, serving as an exposure device, is positioned above the image forming unit 8, and a transfer roller 10, serving as a transfer device, is positioned facing the photosensitive drum 9. A fixing device 11, an exit roller 12a, and a reversing roller 12b are positioned above the transfer roller 10. The fixing device 11 has a thermal fixing configuration and includes, for example, a cylindrical film, a heater unit including a heater and disposed inside the film, and a pressure roller that is in pressure contact with the heater via the film.

[0021] Multiple feeding devices 6 for feeding sheets are deployed below the image forming unit 8. Each of the feeding devices 6 includes a box 6a that serves as a storage unit (storage box) for storing multiple sheets and a feeding unit 6b for feeding sheets one by one from the box 6a.

[0022] When the image forming apparatus 1 performs an image forming operation, the surface of the photosensitive drum 9 in the image forming unit 8 is uniformly charged by a charging device, and the scanner unit 15 emits a laser beam onto the surface of the photosensitive drum 9 based on image information to form an electrostatic latent image. The electrostatic latent image is developed (visualized) using toner supplied from the developing apparatus as a developer, and a toner image is formed on the surface of the photosensitive drum 9.

[0023] In parallel with the operation performed by the image forming unit 8, sheets are fed one by one from the box 6a by the feeding unit 6b in any of the feeding devices 6, and the sheets are conveyed toward the alignment roller 7. After correcting the skew of the sheets, the alignment roller 7 feeds the sheets to the transfer section between the photosensitive drum 9 and the transfer roller 10 in synchronization with the toner image formed by the image forming unit 8. Then, in the transfer section, the toner image is transferred from the photosensitive drum 9 to the sheet.

[0024] The sheet after passing through the transfer section is conveyed to the fixing equipment 11. In the fixing equipment, as the sheet is held by the film and pressure rollers and passes through the fixing clamping section (the clamping section between the heater unit and the pressure rollers), the toner on the sheet is heated and pressurized. Therefore, the toner image is fixed onto the sheet.

[0025] In the case of single-sided printing, the sheet passing through the fixing device 11 is discharged from the image forming apparatus 1 by the discharge roller 12a and received by the relay unit 14. In the case of double-sided printing, the sheet with a toner image formed on the first side and passing through the fixing device 11 is guided by the reversing roller 12b, rotated by the reversing roller 12b, and then fed back to the alignment roller 7 via the re-transfer path 13. Thereafter, an image is formed on the second side opposite the first side by passing through the transfer section and the fixing device 11, and the sheet is conveyed to the relay unit 14 by the discharge roller 12a.

[0026] Image reading device 2 is attached to the top of image forming apparatus 1. Image reading device 2 includes a reading sensor 2s that reads image information from an original document and an original document transport unit that transports original documents one by one to the reading sensor 2s. Image forming apparatus 1 can perform both a copying operation that forms an image based on image information acquired by image reading device 2 and a printing operation that forms an image based on image information received from outside image forming apparatus 1.

[0027] According to this embodiment, a relay unit 14 is deployed in the space (also called the internal discharge space) between the image forming apparatus 1 and the image reading device 2 in the vertical direction (when the image forming system 1S is mounted on a horizontal plane). The relay unit 14 conveys the sheet discharged from the image forming apparatus 1 toward the sheet processing apparatus 4 in a substantially horizontal direction viewed from the front. The sheet processing apparatus 4 is mounted next to the image forming apparatus 1 on a shared mounting surface. The relay unit 14 includes a sheet sensor 52, which serves as a detection unit for detecting the passage of the sheet. The sheet sensor 52 is, for example, a reflective photoelectric sensor that emits infrared light onto the transport path and detects the light reflected by the sheet passing through the transport path to determine the presence of the sheet. Although the image forming system 1S including the relay unit 14 is used as an example, the sheet can be directly conveyed from the image forming apparatus 1 to the sheet processing apparatus 4.

[0028] Furthermore, the image forming apparatus 1 includes a display unit 5 (operation unit, operation display unit) that serves as the user interface for the image forming system 1S. The display unit 5 is capable of displaying system operating statuses such as paper jams and malfunctions, as well as providing instructions for the user to perform operations such as replacing consumables in the apparatus and removing jammed sheets. The user can operate the touch panel function, numeric keys, etc., of the display unit 5's screen to perform various settings and provide instructions to the image forming system 1S.

[0029] It should be noted that the configuration of the image forming apparatus is not limited to... Figure 1The diagram illustrates a direct transfer system. This configuration can be an intermediate transfer system where a toner image formed in an image forming unit is transferred onto a sheet via an intermediate transfer member. The image forming apparatus can be a color image forming apparatus using multiple image forming units. Furthermore, the image forming mechanism is not limited to electrophotographic methods and can employ, for example, an inkjet printing unit or an offset printing mechanism.

[0030] Sheet processing equipment

[0031] The sheet processing apparatus 4 includes a sheet processing device 71 for processing sheets. The sheet processing apparatus 4 has the function of discharging the sheet received from the image forming apparatus 1 and processed by the sheet processing device 71 as a processing result. Alternatively, the sheet processing apparatus 4 can discharge the sheet received from the image forming apparatus 1 as a processing result without performing binding processing.

[0032] The sheet processing apparatus 4 includes a receiving path 81, an internal discharge path 82, a first discharge path 83, and a second discharge path 84 as transport paths for conveying sheet material. Furthermore, the sheet processing apparatus 4 includes an upper discharge tray 25 and a lower discharge tray 37 as discharge destinations for discharging sheet material, each protruding outward from the apparatus body 4A (the housing provided with the receiving path 81, internal discharge path 82, first discharge path 83, and second discharge path 84). The receiving path 81 is a transport path for receiving and conveying sheet material from the image forming apparatus 1, and the internal discharge path 82 is a transport path for conveying the sheet material toward the sheet processing equipment 71. The first discharge path 83 is a transport path for discharging the sheet material to the upper discharge tray 25, and the second discharge path 84 is a transport path for discharging the sheet material to the lower discharge tray 37. As described above, according to this embodiment, the receiving path 81 and the first discharge path 83 form a first conveying path toward the upper discharge tray 25, which serves as a first stacking member, and the inner discharge path 82 is configured as a second conveying path branching from the first conveying path. Additionally, the second discharge path 84 is configured as a third conveying path extending from the sheet handling device 71 toward the lower discharge tray 37, which serves as a second stacking member.

[0033] The receiving path 81 has an inlet roller 21, a pre-branching roller 22, and an inlet sensor 27 disposed therein. The first discharge path 83 has a discharge and reversing roller 24 disposed therein as a reversing conveying unit. The internal discharge path 82 has an internal discharge roller 26, an intermediate conveying roller 28, an ejection roller 29, and a pre-intermediate stacking sensor 38 disposed therein. The second discharge path 84 has a bundle discharge roller 36 disposed therein. The pre-branching roller 22 serves as the first conveying device in this embodiment, the discharge and reversing roller 24 serves as the second conveying device in this embodiment, and the internal discharge roller 26 serves as the third conveying device in this embodiment. Each of the inlet roller 21, the pre-branching roller 22, the discharge and reversing roller 24, the internal discharge roller 26, the intermediate conveying roller 28, the ejection roller 29, and the bundle discharge roller 36 is a roller pair in which the rollers contact each other at their circumferential surfaces to form a clamping portion for clamping and conveying the sheet. The discharge and reversing roller 24 also serves as a discharge device for discharging the sheet.

[0034] The inlet sensor 27 and the pre-intermediate stack sensor 38 are examples of sheet detection units used to detect the passage of sheet material at predetermined detection positions in the conveyor path of a sheet handling apparatus. For example, the inlet sensor 27 and the pre-intermediate stack sensor 38 may be reflective photoelectric sensors that emit infrared light into the interior of the conveyor path and detect the light reflected by the sheet material passing through the conveyor path to determine the presence of sheet material.

[0035] The sheet transport path in the sheet processing apparatus 4 is described below. The sheet transported from the image forming apparatus 1 via the relay unit 14 is received by the inlet roller 21 of the sheet processing apparatus 4 and transported to the pre-branching roller 22 via the receiving path 81. The inlet sensor 27 detects the sheet at a detection position between the inlet roller 21 and the pre-branching roller 22.

[0036] The pre-branching roller 22 conveys the sheet received from the inlet roller 21 toward the first discharge path 83.

[0037] At a predetermined time point after the trailing edge of the sheet is detected by the inlet sensor 27, the pre-branching roller 22 accelerates the sheet conveying speed to a speed higher than that of the relay unit 14. Alternatively, the sheet conveying speed of the inlet roller 21 can be set to be higher than that of the relay unit 14, and the sheet conveying speed can be accelerated by the inlet roller 21 upstream of the pre-branching roller 22.

[0038] In this case, it is desirable to install a one-way clutch between the conveyor roller of the relay unit 14 and the motor that drives the conveyor roller, so that the conveyor roller will idle even when the sheet is pulled by the inlet roller 21.

[0039] When the sheet is destined for the upper discharge tray 25, the discharge and reversing roller 24 discharges the sheet received from the pre-branching roller 22 onto the upper discharge tray 25. In this case, at a predetermined time point after the trailing edge of the sheet has moved past the pre-branching roller 22, the discharge and reversing roller 24 reduces the discharge speed to a predetermined discharge speed.

[0040] When the sheet discharge destination is the lower discharge tray 37, the discharge and reversing roller 24 performs a rotary conveying of the sheet received from the pre-branching roller 22 to transport the sheet to the inner discharge path 82.

[0041] In other words, the discharge and reversing rollers 24 convey the sheet towards the outside of the sheet handling device 4 in the discharge direction, and reverse their rotation direction before the trailing edge of the sheet in the discharge direction moves past the discharge and reversing rollers 24 to convey the sheet in the opposite direction. A check valve 23 is provided at a branch point (between the pre-branching roller 22 and the discharge and reversing rollers 24), where the inner discharge path 82 branches upstream of the discharge and reversing rollers 24 in the discharge direction from both the receiving path 81 and the first discharge path 83. The check valve 23 acts as a guide (restricting member) to limit the backward movement of the sheet rotated by the discharge and reversing rollers 24 towards the receiving path 81. That is, after the trailing edge of the sheet in the discharge direction moves past the check valve 23, the discharge and reversing rollers 24 reverse the conveying direction of the sheet to perform rotary conveying.

[0042] The internal discharge roller 26, intermediate conveyor roller 28, and ejector roller 29, deployed in the internal discharge path 82, sequentially guide the sheet received from the discharge and reversing roller 24 through the next roller to convey the sheet toward the sheet handling apparatus 71. A pre-intermediate stack sensor 38 detects the sheet positioned between the intermediate conveyor roller 28 and the ejector roller 29. The pre-intermediate stack sensor 38 is, for example, a reflective photoelectric sensor that emits infrared light into the interior of the conveyor path and detects the light reflected by the sheet passing through the conveyor path to determine the presence of the sheet.

[0043] The sheet processing apparatus 4 includes a stacking processing unit 4B comprising a discharge and reversal roller 24 and an internal discharge roller 26, and can perform the operation of stacking multiple sheets conveyed from the image forming apparatus 1 onto each other by using the stacking processing unit 4B. According to this embodiment, the stacking processing unit 4B holds a first sheet conveyed via the receiving path 81 in the internal discharge path 82 by using the discharge and reversal roller 24 and the internal discharge roller 26. Subsequently, the stacking processing unit 4B stacks a second sheet conveyed via the receiving path 81 onto the first sheet. The stacking processing unit 4B also has the function of outputting the stacked sheets onto the upper discharge tray 25 (stacked discharge) and the function of conveying the stacked sheets to the sheet processing equipment 71 (buffering function). The configuration and operation of the stacking processing unit 4B are described in detail below.

[0044] After aligning multiple sheets received from the internal discharge path 82, the sheet processing equipment 71 performs a binding process at a predetermined position on the sheet bundle. The sheet processing equipment 71 includes a stapler 50 as a processing device, and an upper intermediate stacking guide 31 and a lower intermediate stacking guide 32 that constitute an intermediate stacking member (processing tray) on which the sheets to be processed are stacked.

[0045] A vertical alignment reference plate 39, serving as a reference component, is positioned downstream of the sheet handling device 71 in the conveying direction of the ejection roller 29. The sheet bundle is aligned in the vertical direction (conveyor direction) by bringing the edge of the sheet in the conveying direction into contact with the vertical alignment reference plate 39. A crescent-shaped roller 33, rotatably supported by the upper intermediate stacking guide 31, is positioned downstream of the pressing guide 56.

[0046] The crescent-shaped roller 33 is a moving member (paddle member, conveying member) used to bring the sheet material passing through the ejector roller 29 into contact with the vertical alignment reference plate 39. After the trailing edge of the sheet material moves past the pre-intermediate stack sensor 38, the crescent-shaped roller 33 conveys the sheet material toward the vertical alignment reference plate 39 at a predetermined time point. The contact pressure of the crescent-shaped roller 33 against the sheet material is adjusted to such a degree that the crescent-shaped roller 33 slides on the sheet material when it contacts the vertical alignment reference plate 39. A flexible pressing guide 56 is fixed to the upper intermediate stack guide 31 and presses the sheet material in the sheet handling device 71 downward with a predetermined pressure to prevent the sheet material from lifting. In addition, a bundle pressing mark 30 is rotatably supported downstream of the ejector roller 29 to prevent the trailing edge of the sheet material from lifting, so that the trailing edge of the sheet material already stacked in the sheet handling device 71 does not interfere with the leading edge of the subsequent sheet material discharged by the ejector roller 29.

[0047] When the alignment of a predetermined number of sheets on the intermediate stacking members is completed, the stapler 50 performs the stapleping operation. Then, the bundle discharge guide 34, which serves as the extrusion member and is driven by the guide drive unit 35, exits from... Figure 1 The waiting position shown in the diagram moves toward the bundle discharge roller 36 (bundle discharge direction). Therefore, the sheet bundle is pushed outside the intermediate stack member. When the leading edge of the sheet bundle in the bundle discharge direction reaches the bundle discharge roller 36, the bundle discharge guide 34 stops and returns to the waiting position. The bundle discharge roller 36, acting as a discharge device (fourth conveying device), discharges the sheet bundle received from the bundle discharge guide 34 to the lower discharge tray 37.

[0048] Both the upper discharge tray 25 and the lower discharge tray 37 are movable vertically relative to the housing of the sheet handling apparatus 4. Sheet presence sensors 51 and 53, used to detect the presence / absence of sheets on the trays, are respectively deployed on the upper discharge tray 25 and the lower discharge tray 37. The sheet presence sensors 51 and 53 are reflective photoelectric sensors, for example, that determine the presence / absence of sheets by emitting infrared light upward from the tray stack surface and detecting the reflected light from the sheets. The sheet handling apparatus 4 also includes a sheet surface detection sensor that detects the upper surface position (sheet stack height) of the sheets on each of the upper discharge tray 25 and the lower discharge tray 37.

[0049] When the sheet surface detection sensor detects a sheet, the corresponding tray in the upper discharge tray 25 and lower discharge tray 37 descends in the A2 or B2 direction. When the sheet presence sensor 51 or 53 detects that a sheet has been removed from the upper discharge tray 25 or lower discharge tray 37, the tray rises in the A1 or B1 direction. The upper discharge tray 25 and lower discharge tray 37 are controlled to move up and down according to the number of stacked sheets, such that the upper surfaces of the stacked sheets are positioned below the vertical discharge and reversing rollers 24 and the bundle discharge roller 36, respectively. According to this embodiment, the upper discharge tray 25, used as a first stacking member, and the lower discharge tray 37, used as a second stacking member, are controlled to rise and fall by a motor drive. However, the upper discharge tray 25 and lower discharge tray 37 can also be configured to rise and fall by a push unit such as a spring.

[0050] The stapler 50 is an example of processing equipment. For example, a sorting mechanism for sorting sheets and a center-folding processing unit for center-folding multiple sheets and performing saddle stitching can be provided.

[0051] Overlay processing unit

[0052] Figure 2 This is an enlarged view of the overlay processing unit 4B. The sheet conveying path (receiving path 81) between the inlet roller 21 and the pre-branching roller 22 consists of the upper inlet guide 40 and the lower inlet guide 41. The sheet conveying path (internal discharge path 82) between the inner discharge roller 26 and the intermediate conveying roller 28 consists of the upper inner discharge guide 46 and the lower inner discharge guide 47. The conveying guide between the pre-branching roller 22 and the discharge and reversing roller 24, which guides the sheet from the same side as the upper inlet guide 40, is called the upper reversing guide 42. The conveying guide between the discharge and reversing roller 24 and the inner discharge roller 26, which guides the sheet from the same side as the lower inner discharge guide 47, is called the lower reversing guide 43. The first discharge path 83 consists of the upper reversing guide 42 and the lower reversing guide 43.

[0053] The sheet conveyed by the inlet roller 21 is guided to the pre-branch roller 22 by the upper inlet guide 40 and the lower inlet guide 41. An inlet sensor 27 is deployed on the upper inlet guide 40. As the inlet sensor 27, a reflective photoelectric sensor can be used to determine the presence of the sheet at the detection location by emitting infrared light into the receiving path 81 and detecting the reflected light from the sheet. In this case, an aperture with a diameter larger than the diameter of the spot light from the inlet sensor 27 is formed in the portion of the lower inlet guide 41 facing the inlet sensor 27, so that infrared light is not reflected when the sheet does not pass through the receiving path 81.

[0054] Check valve 23 is positioned downstream of pre-branching roller 22 and at the branch points of receiving path 81 and internal discharge path 82 from first discharge path 83. Check valve 23 is rotatably supported by upper internal discharge guide 46 via rotating shaft 23a. Furthermore, check valve 23 is always spring-driven (not shown) towards a position where the top of check valve 23 overlaps with upper reversing guide 42 when viewed from the axial direction of rotating shaft 23a (the width direction of the sheet) (see reference). Figure 2 In the C2 direction ( Figure 2 The spring constant is set such that when the sheet conveyed from the pre-branch roller 22 contacts the check valve 23, the check valve 23 resists the biasing force of the spring in the C1 direction (clockwise). Figure 2 The value of rotation in the counterclockwise direction (in the middle). Therefore, check valve 23 allows the sheet conveyed from pre-branching roller 22 toward discharge and reversing roller 24 to pass through it. In addition, when the trailing edge of the sheet in receiving path 81 passes through check valve 23, check valve 23 rotates in the C2 direction and restricts the sheet from returning from discharge and reversing roller 24 to pre-branching roller 22.

[0055] The discharge and reversing roller 24 consists of an upper roller 24a and a lower roller 24b. According to this embodiment, driving force is input to both the upper roller 24a and the lower roller 24b, and the rotation of the upper roller 24a and the lower roller 24b is always synchronized.

[0056] The discharge and reversing rollers 24 are configured to contact each other (closing operation) and separate from each other (opening operation) via a plunger solenoid 45. More specifically, one end of the separating rod 44 is connected to the roller shaft of the upper roller 24a, and the separating rod 44 is rotatably supported by a rod pivot shaft 44a relative to the upper reversing guide 42. A solenoid connecting shaft 44b located at the other end of the separating rod 44 is connected to the plunger of the plunger solenoid 45.

[0057] When the plunger solenoid 45 is energized, the plunger is attracted by magnetic force in the D1 direction. Therefore, the separating rod 44 rotates in the E1 direction, and the discharge and reversing rollers 24 separate from each other (the clamping portion of the roller pair is released). When the plunger solenoid 45 is de-energized, the biasing force of the pressure spring 48 connected to the roller shaft of the upper roller 24a causes the upper roller 24a to contact the lower roller 24b, and the discharge and reversing rollers 24 contact each other (the clamping portion is closed). At this time, as the upper roller 24a moves, the separating rod 44 rotates in the E2 direction, and the plunger of the plunger solenoid 45 moves in the D2 direction.

[0058] The internal discharge roller 26 is formed in the sheet conveying direction of the internal discharge path 82, adjacent to the discharge and reverse roller 24. The roller pair is capable of rotating in both the forward and reverse directions. That is, the internal discharge roller 26 can convey the sheet in both the direction from the discharge and reverse roller 24 to the sheet handling equipment 71 (hereinafter referred to as the G1 direction) and the direction from the sheet handling equipment 71 to the discharge and reverse roller 24 (hereinafter referred to as the G2 direction).

[0059] Hardware configuration

[0060] The following is for reference. Figure 3 The hardware configuration of the image forming system 1S according to this embodiment is described. Figure 3 The main illustration shows the parts of the hardware configuration of the image forming system 1S related to the configuration of the sheet processing device 4. The video controller 601 performs overall control of the image forming system 1S, including the image forming device 1 and the sheet processing device 4. The engine control unit 602 controls the image forming device 1.

[0061] The main control unit 603 controls the sheet processing device 4. Signal line 604 is a serial command transmission line used to transmit commands from the video controller 601 to the engine control unit 602 via serial communication, and signal line 605 is similarly used to transmit commands from the video controller 601 to the main control unit 603. Signal line 606 is a serial status transmission line used to transmit status data from the engine control unit 602 to the video controller 601 via serial communication in response to a command, and signal line 607 is similarly used to transmit status data from the main control unit 603 to the video controller 601. To perform image forming operations, the video controller 601 transmits serial commands to the engine control unit 602 and the main control unit 603, and receives status data from them. Therefore, the video controller 601 performs control. In this way, when multiple devices are connected and the image forming system 1S is operating, the video controller 601 manages the control and status of each device and ensures the consistency of the operations performed by the devices.

[0062] The main control unit 603 includes a central processing unit (CPU) 608 that controls various operations performed by the sheet processing apparatus 4, and a random access memory (RAM) 609 that temporarily stores control data required for the operations performed by the sheet processing apparatus 4.

[0063] The main control unit 603 also includes a non-volatile read-only memory (ROM) 610 for storing control tables and programs required for operations performed by the sheet processing apparatus 4. The main control unit 603 also includes a communication unit 611 for communicating with the video controller 601, a system timer 612 for generating timing required for various controls, and input / output (I / O) ports 613 for inputting / outputting control signals to / from various units of the sheet processing apparatus 4. The main control unit 603 is a control integrated circuit (IC) connected to the above components via a bus 614.

[0064] Input signals from inlet sensor 27, and sheet presence sensors 51 and 53 from upper discharge tray 25 and lower discharge tray 37, are transmitted to main control unit 603 via input circuits 615, 626, and 628, respectively. Control signals from main control unit 603 are transmitted to inlet motor 641, pre-branch motor 642, discharge and reverse motor 643, internal discharge motor 644, and plunger solenoid 45 via drive circuits 618, 619, 620, 621, and 623, respectively. Therefore, the actuator drive is controlled.

[0065] Function block

[0066] Below, for reference Figure 4 The functional blocks of this embodiment will be described below. Figure 4 The main control unit 603 shown in the figure has the function of performing sheet conveying operations by using the sheet handling device 4. The main control unit 603 has at least the functions of a communication unit 611, a system timer 612, a sheet conveying controller 701, a sensor controller 720, a motor controller 721, and a solenoid controller 722.

[0067] Sensor controller 720 is a unit for inputting signals from inlet sensor 27 and sheet presence sensor 51 of upper discharge tray 25 to sheet conveying controller 701. Sheet conveying controller 701 includes stacking conveying controller 711 and sheet counting controller 712. Sheet conveying controller 701 controls motor controller 721 and solenoid controller 722 based on inputs from sensor controller 720 to implement operations performed by stacking processing unit 4B, upper discharge tray 25, and lower discharge tray 37. Stacking conveying controller 711 controls the conveying of sheets to stacking processing unit 4B and upper discharge tray 25 while managing the position of the sheets, primarily based on inputs from sensor controller 720. Sheet counting controller 712 determines the timing for discharging stacked sheets to upper discharge tray 25 based on the maximum number of sheets that can be stacked by stacking processing unit 4B (stackable sheet quantity) and the currently stacked sheet quantity.

[0068] An inlet motor 641 drives the inlet roller 21, a pre-branching motor 642 drives the pre-branching roller 22, and a discharge and reverse motor 643 drives the discharge and reverse roller 24. An internal discharge motor 644 drives the internal discharge roller 26, and a plunger solenoid 45 drives the separating rod 44. The operations performed by these driven components are described in detail below.

[0069] Superimposed discharge operation

[0070] refer to Figures 5A to 5G This describes an overview of the stacking discharge operation (stack discharge operation) in which the stacking transport controller 711 stacks and discharges multiple sheets via the stacking processing unit 4B. Hereinafter, among the sheets to be subjected to the stack discharge operation, the sheet first conveyed from the image forming apparatus 1 to the sheet processing apparatus 4 (the first sheet) is referred to as "sheet S1," and the sheet subsequently conveyed from the image forming apparatus 1 to the sheet processing apparatus 4 (the second sheet) is referred to as "sheet S2." Furthermore, the conveying speed before acceleration (the conveying speed in the relay unit 14) of the pre-branching roller 22, the discharge and reversing roller 24, and the internal discharge roller 26 is defined as V1, and the conveying speed after acceleration is defined as V2. The conveying speed when the discharge and reversing roller 24 discharges the sheet is defined as V3. According to this embodiment, the conveying speed V3 can be varied according to the number of sheets in the bundle.

[0071] refer to Figure 5AAs the trailing edge of the previous sheet S1 passes the inlet sensor 27, the pre-branching roller 22 and the discharge and reversing roller 24 accelerate from speed V1 to speed V2. By accelerating the conveying speed of sheet S1, even if the image forming apparatus 1 is a high-performance machine with high production volume, the sheet interval required for rotation between sheet S1 and the subsequent sheet S2 can be ensured. However, if sheets S1 and S2 do not collide with each other, a configuration where the conveying speed at the inlet sensor 27 is not accelerated can be used. In this case, the conveying speed in the overlay processing unit 4B can always be set to V1. Figure 5A At the moment, the discharge and reversing roller 24 conveys the sheet S1 in the F2 direction.

[0072] refer to Figure 5B When the trailing edge of sheet S1 passes the inlet sensor 27, moves a predetermined distance, and passes the check valve 23, sheet S1 is temporarily stopped. The "predetermined distance" is the distance that the trailing edge of sheet S1 in the F2 direction does not reach the clamping part of the discharge and reversing roller 24 after passing the check valve 23.

[0073] refer to Figure 5C The discharge and reversing rollers 24 change their rotation direction and convey the sheet S1 in the F1 direction at a speed V2. The drive of the inner discharge roller 26 begins before the leading edge of the sheet S1 in the F1 direction reaches the inner discharge roller 26, and the inner discharge roller 26 further conveys the sheet S1 in the G1 direction.

[0074] refer to Figure 5D Sheet S1 is held by the inner discharge roller 26. The conveying of sheet S1 stops when the leading edge of sheet S1 in the G1 direction (F1 direction) moves past the inner discharge roller 26 and has subsequently been conveyed a predetermined distance. This "predetermined distance" is less than the distance from the leading edge of sheet S1 to the intermediate conveying roller 28. While sheet S1 is held by the inner discharge roller 26, the upper roller 24a of the discharge and reversing roller 24 moves in the E1 direction via the separating rod 44 to separate from the lower roller 24b. Note that the discharge and reversing roller 24 is driven to separate from each other before the leading edge of subsequent sheet S2 reaches it.

[0075] refer to Figure 5EAfter the trailing edge of the subsequent sheet S2 passes the inlet sensor 27, the pre-branching roller 22 and the discharge and reversing roller 24 are accelerated to speed V2 in the same manner as the previous sheet S1. When the trailing edge of the sheet S2 passes the inlet sensor 27 and a predetermined time T_wait has elapsed thereafter, the inner discharge roller 26 begins to rotate again toward the discharge and reversing roller 24, and the sheet S1 is conveyed in the G2 direction. The predetermined time T_wait is described in more detail below. When the relative speeds of the sheets S1 and S2 become equal, the upper roller 24a of the discharge and reversing roller 24 is driven in the E2 direction and contacts the lower roller 24b, and the discharge and reversing roller 24 simultaneously clamps the sheets S1 and S2. At this time, the leading edges of the sheets S1 and S2 in the F2 direction are aligned. In addition, before the discharge and reversing roller 24 clamps the sheets S1 and S2, the rotational speed of the discharge and reversing roller 24 is adjusted to be equal to the speed V2, which is the conveying speed of the sheets S1 and S2.

[0076] refer to Figure 5F When the trailing edge of sheet S2 passes through check valve 23, sheets S1 and S2 form a sheet bundle S' in the F2 direction where the leading and trailing edges of sheets S1 and S2 are aligned.

[0077] refer to Figure 5G Before reaching a distance L from the discharge and reversal roller 24, the speed of the sheet bundle S' changes to speed V3, and the sheet bundle S' is discharged by the discharge and reversal roller 24 to the upper discharge tray 25.

[0078] Therefore, in the overlay processing unit 4B, the operation of simultaneously aligning and overlaying two sheets S1 and S2 and then discharging them (overlay discharge operation) is completed. When image forming operations are performed continuously on a large number of sheets, the two sheet bundles are stacked on the upper discharge tray 25 by repeating the above overlay discharge operation.

[0079] The advantages of this embodiment are described below compared to the case where sheets S1 and S2 are discharged one by one without undergoing a stacked discharge operation. When sheets S1 and S2 are discharged one by one, their position and orientation may be lost before they fall onto the upper surface of the upper discharge tray 25 or the upper surface of the sheets on the upper discharge tray 25 after passing through the discharge and reversing rollers 24. This is because each of sheets S1 and S2 experiences air resistance during descent and thus moves in all directions when viewed from above.

[0080] In contrast, according to this embodiment, the positions of sheets S1 and S2 are aligned in the sheet conveying direction, and sheets S1 and S2 are pre-stacked and discharged, making it unlikely that the positions and orientations of sheets S1 and S2 will be lost.

[0081] When comparing the sheet bundle ejected via the stacking ejection operation with the sheets ejected individually, the projected area of ​​the sheet (bundle) and the individual sheet is the same when viewed from above, but the weight of the sheet bundle is twice that of the individual sheet. For this reason, the sheet bundle is less susceptible to air resistance. As a result, even when increasing the sheet ejection speed of the ejection and reversing rollers 24 to improve the productivity of the image forming system 1S and the sheet processing apparatus 4, the deterioration of sheet stackability can be avoided.

[0082] Three or more sheets stacked and discharged

[0083] Although the above description has been made with reference to the conveying of two sheets, the sheet handling apparatus 4 of this embodiment can perform a stacking discharge operation to align the positions of three or more sheets, stack the sheets on top of each other in the stacking processing unit 4B, and discharge the sheets to the upper discharge tray 25.

[0084] When performing a stacking and ejection operation on three sheets, first refer to the above reference. Figures 5A to 5F The same process described is used to superimpose two sheets, S1 and S2. Afterwards, Figure 5F The discharge and reversing roller 24 shown in the diagram is reversed again, causing the sheet bundle S' to be conveyed in the G1 direction. Subsequently, the third sheet S3 undergoes... Figures 5C to 5F The same operation is performed on sheet S2, while sheet bundle S' undergoes the same operation. Figures 5C to 5F The same operation is performed on sheet S1.

[0085] As a result, after the sheet bundle S' is temporarily stopped while being held by the internal discharge roller 26 in the internal discharge path 82, the internal discharge roller 26 conveys the sheet bundle S' in the G2 direction when a predetermined time T_wait has elapsed since the inlet sensor 27 detects the trailing edge of the third sheet S3. Thereafter, the opened discharge and reversing roller 24 closes, so that the three sheets S1, S2, and S3 are simultaneously held by the discharge and reversing roller 24. When the trailing edge of sheet S3 passes the check valve 23, a sheet bundle is formed in which both the leading and trailing edges of the three sheets S1, S2, and S3 are aligned.

[0086] When the number of sheets in the stacked discharge operation is 3, the sheet bundle is directly discharged in the G2 direction by the discharge and reversing roller 24 and stacked on the upper discharge tray 25. When the number of sheets in the stacked discharge operation is 4 or more, the discharge and reversing roller 24 conveys the sheet bundle again in the G1 direction, and repeats the process. Figures 5C to 5F The same operation applies. In this way, the number of sheets to be stacked can be increased.

[0087] The sheet counting controller 712 manages the number of sheets to be stacked in the stacking processing unit 4B based on the number of sheets that can be stacked by the stacking processing unit 4B and information about the sheets to be conveyed. That is, the sheet counting controller 712 determines whether the sheets conveyed to the stacking processing unit 4B are immediately discharged onto the upper discharge tray 25 or stacked on top of each other.

[0088] As an example of the defined technique, let N represent the number of sheets that can be stacked by the stacking processing unit 4B. The sheet counting controller 712 then generates a bundle of N-1 sheets and discharges this bundle to the upper discharge tray 25. The number of sheets to be stacked is only set to N when the sheet counting controller 712 determines that the Nth sheet is the last sheet. In this way, the sheet counting controller 712 prevents the Nth sheet from being discharged to the upper discharge tray 25 as a single sheet.

[0089] As a specific example, in the configuration example according to this embodiment, the number of sheets that can be stacked by the stacking processing unit 4B is 5. In this case, the sheet counting controller 712 repeatedly performs the stacking discharge operation on four sheets and stacks the sheet bundle of the four sheets on the upper discharge tray 25. At this time, if the sheet counting controller 712 determines that the fifth sheet is the last sheet and the last sheet is discharged as a sheet when the stacking discharge operation on the four sheets is repeated to the end, then the stacking discharge operation on the five sheets including the last sheet is performed, and the sheets are discharged to the upper discharge tray 25. If even when the stacking discharge operation on the four sheets is performed to the end, the last sheet is also stacked on another sheet, then when forming a sheet bundle including the last sheet, the sheet bundle is also discharged to the upper discharge tray 25.

[0090] That is, when performing the operation of discharging a predetermined number of sheets onto the upper discharge tray 25, the sheet counting controller 712 changes the number of sheets in the bundle formed by the stacking discharge operation according to the predetermined number of sheets, such that each of the predetermined number of sheets is always included in a bundle of two or more sheets formed by the stacking discharge operation and is discharged onto the upper discharge tray 25. As a result, single sheets can be prevented from being discharged onto the upper discharge tray 25, and thus deterioration of sheet stackability can be prevented. Note that the technique used to control the number of sheets in the stacking discharge operation is not limited to this. Any technique that avoids the discharge of single sheets can be used. For example, in the example above, the number of sheets in consecutive stacking discharge operations can be four, ..., four, three, and two.

[0091] How to find T_wait

[0092] The timing management (for obtaining the above-mentioned T_wait) is described, which is performed by the stacking transport controller 711 to align the leading edges of sheets S1 and S2 in the stacking processing unit 4B.

[0093] Figure 7A The diagram illustrates the positional relationship between sheets S1 and S2 at the moment when the inlet sensor 27 detects the trailing edge of sheet S2. Distance L1 is the distance from the detection position of the inlet sensor 27 to the clamping position of the discharge and reversing roller 24 (measured along the receiving path 81 and the first discharge path 83). Distance L2 is the distance from the position where the leading edge of sheet S2, after reversing past the inner discharge roller 26, moves a predetermined distance d1 and stops to the clamping portion of the discharge and reversing roller 24 (measured along the first discharge path 83 and the inner discharge path 82).

[0094] Figure 7B The illustration shows when Figure 7A The positional relationship between sheets S1 and S2 is defined when the conveying of sheet S1 begins in the F2 direction (G2 direction) and the conveying speed of sheet S1 becomes equal to the conveying speed of sheet S2. At this point, it is assumed that the trailing edges of sheets S1 and S2 in the F2 direction are offset from each other by a protrusion amount Kt.

[0095] Figure 7C The illustration shows that Figure 7A and Figure 7B The diagram illustrates the speed change of each of sheets S1 and S2 during the operation. Figure 7C In the text, "A" indicates that... Figure 7A The inlet sensor 27, as shown in the diagram, detects the trailing edge of sheet S2 at which point the pre-branching roller 22 begins to accelerate from speed V1 to speed V2 with a constant acceleration. Figure 7C In the text, "B" represents the time it takes for sheet S2 to accelerate to speed V2.

[0096] exist Figure 7C In this context, "C" represents the time elapsed since the inlet sensor 27 detected the trailing edge of sheet S2, which is the time when the internal discharge roller 26 begins conveying sheet S1 in the G2 direction. Figure 7C In the text, "D" indicates that... Figure 7B The diagram shows the time it takes for the relative velocity between sheets S1 and S2 to become zero.

[0097] Let T_merge represent the time elapsed from A to D. Let T1 represent the time required for the pre-branching roller 22 to accelerate from speed V1 to speed V2 (the time elapsed from A to B). Let T2 represent the time from the acceleration of the pre-branching roller 22 to speed V2 until the rotation of the inner discharge roller 26 begins (the time elapsed from B to C). As can be seen from the definitions of T1, T2, and T_wait, T_wait = T1 + T2. Let T3 represent the time required for the stopped sheet S1 to accelerate to speed V2 with constant acceleration (the time elapsed from C to D).

[0098] Let X2 represent the sheet material S1 from Figure 7A Move the position in the middle to Figure 7B The distance from the position in the middle. Then, from the above description, it can be seen that X2 is the distance from the sheet S1 from... Figure 7C The distance C moves to D can be given by the following formula:

[0099] X2=(V2×T3) / 2 (1).

[0100] Additionally, let X1 represent the sheet S2 from... Figure 7A Move the position in the middle to Figure 7B The distance from the position in the middle. Therefore, X1 is the distance from sheet S2 from... Figure 7C The distance that A moves to D in the equation can be given by the following formula:

[0101] X1=(V1+V2)×T1 / 2+V2×(T2+T3) (2).

[0102] from Figure 7B Based on the positional relationship between sheets S1 and S2 at any given moment, the following relationship holds:

[0103] L1-X1=L2-X2-Kt (3).

[0104] Substituting equations (1) and (2) into equation (3) and expanding and rearranging the equation, we obtain the following equation:

[0105] L1-L2+Kt

[0106] =(T1 / 2)×V1+(T1 / 2+T2+T3 / 2)×V2 (4).

[0107] Substituting T_wait=T1+T2 into the above equation (4) and rearranging the equation, for the protrusion Kt, the waiting time T_wait from when the trailing edge of sheet S2 passes the inlet sensor 27 to when the internal discharge roller 26 starts conveying sheet S1 is given by the following formula:

[0108] T_wait=(L1-L2+Kt) / V2-(T1 / 2)×V1 / V2+(T1-T3) / 2(5).

[0109] To align the leading and trailing edges of sheets S1 and S2 and stack them, the waiting time T_wait can be calculated by setting Kt = 0 in equation (5) above. By starting to feed sheet S1 from the internal discharge roller 26 based on the calculated T_wait, a sheet bundle S' with the leading and trailing edges of sheets S1 and S2 aligned can be formed. Alternatively, when three or more sheets are stacked, a sheet bundle with the leading and trailing edges aligned can be formed by using the same T_wait value.

[0110] Control Example

[0111] The following is for reference. Figure 6A and Figure 6B The flowchart shown in the figure describes the control implementation reference. Figures 5A to 5G This describes an example of a method for the sheet processing apparatus 4 in the superimposed ejection operation. The process is executed whenever the main control unit 603 of the sheet processing apparatus 4 receives a notification from the video controller 601 that a sheet has been ejected from the image forming apparatus 1. Unless otherwise specified, the steps of the flowchart are as follows: Figure 4 The superimposed conveyor controller 711 shown in the middle diagram is activated.

[0112] In the following description, the term "first sheet" refers to the sheet that is first conveyed to the sheet handling device 4 among the sheets to be stacked in the stacking processing unit 4B to form a sheet bundle. For example, when four sheets are stacked and discharged onto the upper discharge tray 25, the sheet conveyed to the sheet handling device 4 after the last sheet of the previous sheet bundle (i.e., the 4n+1th sheet) is the first sheet. The term "last sheet" refers to the last sheet to be conveyed to the sheet handling device 4 among the sheets to be stacked in the stacking processing unit 4B to form a sheet bundle (i.e., the 4nth sheet in the above example).

[0113] In step S101, the inlet roller 21 and the pre-branching roller 22 begin to rotate at a speed V1. The process then proceeds to step S102. If the inlet roller 21 and the pre-branching roller 22 have already rotated at a speed V1, the rotation of the rollers continues.

[0114] In step S102, it is determined whether the current sheet is the first sheet. If it is, the process proceeds to step S103; otherwise, the process proceeds to step S106.

[0115] In step S103, the discharge and reversing rollers 24 are brought into contact with each other, and rotation of the discharge and reversing rollers 24 begins at a speed V1 in the direction (G2 direction) in which the first sheet is conveyed toward the upper discharge tray 25 (see reference). Figure 5A (Sheet S1 in the middle). Proceed to step S104.

[0116] In step S104, it is determined whether the trailing edge of the first sheet has passed the inlet sensor 27. If yes, the process proceeds to step S105; otherwise, the process proceeds to step S104.

[0117] In step S105, the pre-branching roller 22 and the discharge and reversing roller 24 are accelerated to a speed V2 (reference). Figure 5A (Sheet S1 in the middle). Proceed to step S111.

[0118] In step S106, it is determined whether the trailing edge of the current sheet (one of the second sheet and the subsequent sheet) has passed the inlet sensor 27. If yes, the process proceeds to step S107; otherwise, the process proceeds to step S106.

[0119] In step S107, the pre-branching roller 22 and the discharge and reversing roller 24 are accelerated to speed V2. As a result, the current sheet conveying speed is accelerated from speed V1 to speed V2 (reference). Figure 5D (Sheet S2 in the middle). Proceed to step S108.

[0120] In step S108, it is determined whether a predetermined time T_wait has elapsed since the trailing edge of the current sheet passed the entry sensor 27. If yes, the process proceeds to step S109; otherwise, the process proceeds to step S108.

[0121] In step S109, the rotation of the inner discharge roller 26 is restarted at a speed V2 in the direction (F2 direction) in which the sheet is conveyed toward the discharge and reverse roller 24 (see reference). Figure 5D (Sheet S1 in the middle). Proceed to step S110.

[0122] In step S110, when the conveying speed of the sheet (bundle) transported by the internal discharge roller 26 is equal to the current sheet conveying speed, the upper roller 24a of the discharge and reversing roller 24 moves in the E2 direction to contact the lower roller 24b (see reference). Figure 5E As a result, the sheet (bundle) conveyed by the internal discharge roller 26 and the current sheet are simultaneously discharged and clamped by the reverse roller 24 (see reference). Figure 5E Proceed to step S111.

[0123] In step S111, it is determined whether the current sheet is the last sheet. If it is, the process proceeds to step S112; otherwise, the process proceeds to step S116.

[0124] In step S112, the sheet bundle, including the last sheet, is discharged onto the upper discharge tray 25 (reference). Figure 5FThat is, the sheet feeding that began in step S107 or S109 continues by using the discharge and reversal rollers 24 and the internal discharge rollers 26.

[0125] In step S113, when the trailing edge of the sheet bundle reaches a distance L from the discharge and reversing roller 24, the conveying speed of the discharge and reversing roller becomes speed V3, and the sheet bundle is discharged onto the upper discharge tray 25. According to this embodiment, the discharge speed V3 is set according to the number of sheets in the sheet bundle to be discharged.

[0126] In step S114, it is determined whether the trailing edge of the sheet bundle has passed the discharge and reversal roller 24. If yes, the process proceeds to step S115; otherwise, the process proceeds to step S114.

[0127] In step S115, the pre-branching roller 22 is decelerated to speed V1, and the discharge and reversing roller 24 and the internal discharge roller 26 stop. Therefore, the process ends. If the current sheet is the last sheet in the operation (if no more sheets are being fed from the image forming apparatus 1), then in step S115, the inlet roller 21 and the pre-branching roller 22 also stop.

[0128] In step S116, it is determined whether the trailing edge of the current sheet (excluding the last sheet) has passed through check valve 23. If yes, the process proceeds to step S117; otherwise, the process proceeds to step S116.

[0129] In step S117, the discharge and reverse rollers 24 and the internal discharge roller 26 are temporarily stopped (see reference). Figure 5B The sheet material S1 is processed to step S118.

[0130] In step S118, the rotation of the discharge and reversing roller 24 and the rotation of the inner discharge roller 26 begin at a speed V2 in the rotational direction used to convey the sheet (bundle) in the reversed direction (F1 direction, G1 direction) (see reference). Figure 5C The sheet material S1 is processed to step S119.

[0131] In step S119, it is determined whether the leading edge of the sheet (bundle) has passed the inner discharge roller 26. If yes, the process proceeds to step S120; otherwise, the process proceeds to step S119.

[0132] In step S120, the upper roller 24a of the discharge and reversing roller 24 separates from the lower roller 24b. The process proceeds to step S121.

[0133] In step S121, at the position where the leading edge of the sheet (bundle) has passed the inner discharge roller 26 and been conveyed a predetermined distance, the pre-branching roller 22 is decelerated to speed V1, and the discharge and reversing rollers 24 and the inner discharge roller 26 stop. Therefore, the process ends. As a result, the sheet (bundle) that is the target of the stacking discharge operation and is still stacked on other sheets is held while being clamped by the inner discharge roller 26 (see reference). Figure 5D The sheet S1 in the middle).

[0134] As described in step S113, according to this embodiment, the discharge speed V3 is set according to the bundle of sheets to be discharged. See below for reference. Figure 8 The reason for this setup is explained below. The flight distance of the sheet bundle discharged by the discharge and reversing rollers 24 varies depending on the number of sheets in the bundle. If air resistance R is ignored, the flight trajectory of the sheet bundle is determined by the initial velocity V3 of the sheet material upon discharge and the discharge angle θ. Therefore, the flight distance is constant regardless of the number of sheets in the bundle. In reality, air resistance R acts on the sheet material and changes the discharge trajectory of the sheet bundle for each number of sheets in the bundle.

[0135] For this reason, if the discharge speed V3 is constant regardless of the number of sheets in the bundle, then as Figure 8 As illustrated in the diagram, the flight distance of the sheet bundle from the discharge and reversal rollers 24 varies, leading to deterioration of stackability or discharge failure. If the flight distance of the discharged sheet bundle is too large, the sheet bundle may jump out of the sheets already stacked on the upper discharge tray 25. If the flight distance of the sheet bundle is insufficient, the trailing edge of the sheet bundle is caught by the discharge and reversal rollers 24, resulting in discharge failure.

[0136] Therefore, according to this embodiment, the discharge speed V3 is set according to the number of sheets in the bundle to be discharged in order to avoid the above-mentioned problems. Figure 9A The diagram illustrates the flight trajectory when the ejection speed is set to a constant value regardless of the number of sheets in the bundle. Figure 9B The diagram illustrates the flight trajectory when the discharge velocity is varied according to the number of sheets in the bundle.

[0137] like Figure 9A The diagram illustrates the variation in flight distance of the bundle from the discharge and reversing rollers 24 when the discharge speed is set to a constant value (discharge speed V31) regardless of the amount of sheet material in the bundle. Therefore, as shown... Figure 9B The diagram shows different discharge speeds. Specifically, the discharge speed for a bundle of two sheets is set to V32, for a bundle of three sheets to V33, and for a bundle of four sheets to V34. The result is as follows... Figure 9BAs illustrated in the diagram, the flight distance of the sheet bundle from the discharge and reversing rollers 24 can be kept constant. As the number of sheets in the bundle increases, the mass of the bundle increases. Therefore, the sheet bundle is less likely to be affected by air resistance, thus increasing the flight distance. Therefore, the discharge speed V3 is set such that the discharge speed V3 decreases as the number of sheets in the bundle increases.

[0138] That is, when the number of sheets in the sheet bundle is a first number of sheets (e.g., 2 sheets), the discharge speed V3 is set to a first discharge speed (e.g., discharge speed V32). When the number of sheets in the sheet bundle is a second number of sheets (e.g., 3 sheets) that is greater than the first number of sheets, the discharge speed V3 is set to a second discharge speed that is lower than the first discharge speed (e.g., discharge speed V33).

[0139] As a result, regardless of the number of sheets in the bundle, the sheet bundle can be discharged to the target location, thereby improving stackability. Note that the discharge speed V3 can be changed no later than before the trailing edge of the sheet bundle passes the discharge and reversal roller 24.

[0140] Instead of adjusting the discharge speed V3 based on the number of sheets in the bundle, a threshold can be set for the number of sheets in the bundle. For example, when the number of sheets in the bundle is 2 or 3, the discharge speed V3 can be set to a first discharge speed. When the number of sheets in the bundle is 4 (greater than or equal to the threshold), the discharge speed V3 can be set to a second discharge speed (in this case, the threshold is 4 sheets). The discharge speed V3 can be appropriately set based on the discharge angle of the discharge and reversing rollers 24, the positional relationship between the upper discharge tray 25 and the discharge and reversing rollers 24, etc.

[0141] In some cases, the flight distance is varied depending on the basis weight of the sheet, thus affecting stackability. For example, Figure 10A The diagram illustrates the discharge trajectory of a sheet bundle S'w1 with a basis weight W1. Depending on the number of sheets in the bundle, the discharge velocity V3 is set to one of V32 to V34. In this setup, when the sheet bundle S'w2 with a basis weight W2 is discharged, its flight distance differs from that of the sheet bundle S'w1 with a basis weight W1. Figure 10B More specifically, the effect of air resistance increases as the basis weight of the sheet decreases, thus reducing the flight distance of the sheet bundle.

[0142] Therefore, when forming a bundle (first sheet bundle) consisting of multiple sheets of the first basis weight, the discharge speed V3 is set to a third discharge speed. When forming a bundle (second sheet bundle) consisting of multiple sheets of the second basis weight (sheets of a basis weight less than the first basis weight), the discharge speed V3 is set to a fourth discharge speed. The fourth discharge speed is set to be greater than the third discharge speed.

[0143] Additionally, in some cases, the flight distance varies depending on the sheet size, thus affecting stackability. In such cases, the discharge speed V3 setting can be adjusted according to the sheet size and number of sheets, in the same manner as described above. Furthermore, in some cases, the sheet curling direction varies depending on the printing mode (e.g., double-sided or single-sided printing) or media type. Figure 11A and Figure 11B The effect of air resistance R on the sheet bundle can vary depending on the curling direction, resulting in differences in flight distance. Consequently, the flight distance of the ejected sheet bundle may vary, and stackability may deteriorate. In this case, the ejection speed V3 setting can be varied according to the printing mode or media type and the number of sheets in the bundle, in the same manner as described above.

[0144] As described above, according to this embodiment, when multiple sheets are continuously conveyed and discharged onto the first stacking member, the stacking processing unit 4B can stack multiple sheets while aligning their edges, and then discharge the sheets. As a result, the stackability of the sheets on the first stacking member can be improved while maintaining productivity. Furthermore, when the stacking processing unit 4B stacks multiple sheets while aligning their edges and then discharges the sheets, the discharge speed can be varied according to the number of sheets forming a bundle. As a result, the flight distance of the sheet bundle discharged from the discharge and reversing rollers 24 onto the first stacking member can be kept constant, thus improving the stackability of the sheets.

[0145] Although the maximum number of sheets that can be superimposed by the superposition processing unit 4B (the number of sheets that can be superimposed) has been referenced as five configuration examples describing this embodiment, the number of sheets that can be superimposed can be appropriately changed according to the specific configuration of the superposition processing unit 4B and the performance required by the superposition processing unit 4B.

[0146] Buffering operations performed by sheet processing equipment

[0147] In this embodiment, the overlay processing unit 4B can also function as a buffer unit for overlaying and holding the sheets received from the image forming apparatus 1 when the sheet processing apparatus 71 is processing sheets. By performing the buffering operation, collisions of the sheets in the sheet processing apparatus 71 are avoided without reducing the productivity of the image forming apparatus 1. As a result, the productivity of the image forming system 1S is improved.

[0148] When performing the buffering operation, the operation performed by the stacking processing unit 4B is essentially the same as the stacking discharge operation, except that the stacked sheet bundle is conveyed to the sheet processing equipment 71 via the internal discharge path 82. That is, in Figures 5A to 5G In the operation shown in the diagram, Figure 5FThe stacked sheet bundles shown in the diagram are not discharged onto the upper discharge tray 25, but are instead conveyed to the sheet processing equipment 71 via, for example, the inner discharge roller 26. Furthermore, after the sheet bundles are conveyed to the sheet processing equipment 71, subsequent sheets that do not require buffering are rotated one by one via the discharge and reversal rollers 24, and then conveyed to the sheet processing equipment 71.

[0149] In buffering operations, the bulge amount Kt( Figure 7B The sheet can be configured such that the leading edges of the stacked sheets are offset from each other by a predetermined distance. In this case, it is desirable to set the protrusion Kt such that the lower sheet in the sheet handling device 71 ( Figure 7B The sheet S1 in the sheet conveying direction toward the sheet handling equipment 71 protrudes further downstream. In this way, the crescent roller 33 can come into contact with each of the sheets in the bundle that are stacked by the buffer operation, and the alignment operation can be performed effectively.

[0150] As described above, the stacking processing unit 4B of this embodiment has the function of performing a stacking discharge operation when the sheet is discharged outside the sheet processing apparatus 4 without performing the processing performed by the sheet processing equipment 71, and also has the function of buffering the sheet to be processed by the sheet processing equipment 71. As a result, compared with a configuration that includes two mechanisms for stacking the sheet to achieve the above two functions, the size and cost of the apparatus can be reduced.

[0151] Variations

[0152] According to this embodiment, the internal discharge path 82, which serves as the second conveying path, is connected to the sheet handling device 71. However, it is also possible to employ a configuration where the second conveying path is connected to a discharge destination other than the sheet handling device 71. For example, the sheet handling device 71 can be removed, and the sheet conveyed via the internal discharge path 82 can be discharged to the lower discharge tray 37 without processing. Alternatively, a configuration can be adopted where the second conveying path has an end and is not connected to the outside of the sheet handling device 4.

[0153] Furthermore, although this embodiment has been described with reference to the sheet discharge device of the sheet processing device 4 which is provided separately from the image forming apparatus 1, this technology is applicable to sheet discharge devices that discharge sheets from the image forming apparatus 1 or other devices that process sheets.

[0154] Furthermore, according to this embodiment, the bundle discharge roller 36 used to discharge the sheets processed by the sheet processing equipment 71 to the lower discharge tray 37 can be used as a discharge device. When the bundle discharge roller 36 discharges the sheet bundle, the discharge speed can be appropriately set according to the number of sheets forming the sheet bundle.

[0155] Other embodiments

[0156] The present invention can also be implemented by performing the following process: a program providing at least one of the functions in the above embodiments is supplied to a system or device via a network or storage medium, and at least one processor of the computer of the system or device reads and executes the program. Alternatively, the present invention can be implemented by using a circuit (e.g., an application-specific integrated circuit (ASIC)) that provides at least one function.

[0157] While the invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

Claims

1. A sheet discharge device, comprising: A first stacking component is disposed outside the main body of the device; A first conveying device is deployed in the main body of the device in a first conveying path extending toward the first stacked member, wherein the first conveying device conveys the sheet to the first stacked member; A discharge device configured to receive sheets conveyed by the first conveying device and discharge the sheets to the first stacking member, wherein the discharge device discharges multiple sheets, each conveyed from the first conveying device, in the form of a bundle of sheets; A sheet processing apparatus configured to receive and process sheets that have not been discharged by the discharge apparatus. A second stacking member, disposed outside the main body of the device, wherein sheets processed by the sheet processing equipment are stacked on the second stacking member; and A controller configured to control the first conveying device and the discharge device to perform a bundle discharge operation for discharging the sheet bundle from the discharge device onto the first stacking member. Wherein, the controller sets the discharge speed of the sheet discharge device to a first discharge speed when the sheet bundle includes a first number of sheets, and sets the discharge speed to a second discharge speed lower than the first discharge speed when the sheet bundle includes a second number of sheets, wherein the second number of sheets is greater than the first number of sheets, and The first flight distance when the first number of sheets are discharged into the first stack member at the first discharge rate is closer than the third flight distance when the second number of sheets are discharged into the first stack member at the first discharge rate, which is closer than the second flight distance when the second number of sheets are discharged into the first stack member at the second discharge rate.

2. The sheet discharge device according to claim 1, wherein, The discharge device is a second conveying device deployed downstream of the first conveying device in the first conveying path, and The discharge device is capable of reversing the conveying direction of the sheet received from the first conveying device and conveying the sheet to a second conveying path, which branches off from the first conveying path between the first conveying device and the second conveying device.

3. The sheet discharge device according to claim 2, further comprising: A detection component configured to detect sheet material passing through the first conveying path; as well as A third conveying device, deployed within the second conveying path, receives and conveys the sheet material reversed by the second conveying device. The controller controls the first conveying device, the second conveying device, and the third conveying device to perform the bundle discharge operation. In the bundle discharge operation, after the first sheet conveyed in the first conveying path is transferred to the third conveying device via the second conveying device, the conveying of the first sheet by the third conveying device stops, and when a predetermined time has elapsed since the detection member detected the second sheet subsequently conveyed in the first conveying path, the first sheet is conveyed by the third conveying device to the second conveying device, such that a bundle of the first sheet and the second sheet is formed with their edges aligned in the sheet conveying direction, and is discharged onto the first stacking member via the second conveying device.

4. The sheet discharge device according to claim 3, wherein, In the bundle discharge operation, the controller is capable of forming a bundle of three or more sheets including the first sheet and the second sheet, and discharging the bundle of sheets to the first stacked member using the second conveying device.

5. The sheet discharge device according to claim 3, wherein, When performing the operation of discharging a predetermined number of sheets into the first stack member, the controller changes the number of sheets in the bundle of sheets formed by the bundle discharge operation according to the predetermined number of sheets, such that each of the predetermined number of sheets is always included in a bundle of two or more sheets formed by the bundle discharge operation and is discharged into the first stack member.

6. The sheet discharge device according to claim 3, wherein, The sheet processing equipment performs a binding operation on the sheets conveyed via the second conveying path.

7. The sheet discharge device according to claim 6, wherein, When the bundle discharge operation is not performed, the controller, while the sheet processing equipment is processing sheets, stacks multiple sheets conveyed from outside the sheet processing device to the first conveying path using the first conveying device, the second conveying device, and the third conveying device, and after the processing performed by the sheet processing equipment, the controller conveys the multiple sheets to the sheet processing equipment.

8. The sheet discharge device according to claim 6, wherein, The sheet processing equipment includes an intermediate stacking member disposed in the main body of the device, a reference member disposed downstream of the intermediate stacking member in the sheet discharge direction from the second conveying path to the intermediate stacking member, a moving member configured to move and align the sheet to be discharged to the intermediate stacking member toward the reference member, and an extrusion member configured to extrude the sheet processed by the sheet processing equipment in a direction opposite to the discharge direction. The second stacking component is deployed below the first stacking component.

9. An image forming system, comprising: An image forming apparatus configured to form an image on a sheet; as well as The sheet discharge device according to claim 6.

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