JP2022083972A - Sheet discharge device, sheet processing device, and image forming system - Google Patents

Abstract

To improve lamination property of discharged sheets while maintaining productivity.SOLUTION: Control means for a sheet discharge device is configured to perform a discharge operation for causing second conveyance means to reverse a first sheet received from first conveyance means and transfer the same to third conveyance means, causing the third conveyance means to convey the first sheet toward the second conveyance means upon issuance of a detection signal from detection means in accordance with a second sheet conveyed after the first sheet, and causing the second conveyance means to discharge the first and second sheets to a lamination part in a state in which the ends of the first and second sheets in a conveyance direction are aligned and stacked.SELECTED DRAWING: Figure 5

Description

The present invention relates to a sheet discharging device for discharging a sheet, a sheet processing device for processing a sheet, and an image forming system for forming an image on the sheet.

An image equipped with a sheet processing device (also called a finisher) that performs sorting processing, binding processing, matching processing, etc. on the image-formed sheet as an option of the image forming apparatus such as an electrophotographic copying machine or a laser beam printer. The forming system is known. When the sheet processing device continuously processes a plurality of sheet bundles, the image forming system is configured to suspend the acceptance of sheets from the image forming apparatus in order to wait for the processing of the preceding sheet bundle to be completed. Productivity (throughput) will decrease.

Therefore, during the processing of the sheet bundle, the sheets received from the image forming apparatus are temporarily held (buffered) while being superposed inside the sheet processing apparatus, and after the processing of the sheet bundle is completed, the sheets are loaded on the processing tray as a sheet bundle. It has been known. Patent Document 1 describes a configuration in which a sheet received from an image forming apparatus is held by using two transfer paths branched inside the finisher, and the two sheets are superposed and loaded on a processing tray.

Tokushu Kohei 06-909070

By the way, when the sheet transport speed is increased in order to further improve the productivity of the image forming system, the sheet is vigorously discharged from the image forming device or the sheet processing device, and the sheet discharged to the discharge destination such as the discharge tray is discharged. The loading position tended to be disturbed.

Therefore, an object of the present invention is to provide a sheet discharging device, a sheet processing device, and an image forming system capable of improving the loadability of discharged sheets while maintaining productivity.

One aspect of the present invention includes a loading section on which a sheet is loaded, a first transport means arranged on a first transport path extending toward the loading section, and transporting the sheet toward the loading section, and the first transport unit. A detection means that emits a detection signal according to a sheet passing through a transport path, and a second transport means arranged downstream of the first transport means on the first transport path, which are received from the first transport means. On the second transport means for reversing the transport direction of the sheet and transporting the sheet to the second transport path branched from the first transport path between the first transport means and the second transport means, and on the second transport path. The arranged third transport means, that is, a third transport means that reverses the transport direction of the sheet and transports the sheet, and a control means that controls the first transport means, the second transport means, and the third transport means. , The control means causes the second transport means to invert the first sheet received from the first transport means and deliver it to the third transport means, and the first sheet is subsequently transported. Based on the fact that the detection means emits the detection signal in response to the second sheet, the third transport means is made to transport the first sheet toward the second transport means, and the first sheet and the said. With the ends of the second sheet in the transport direction aligned and the first sheet and the second sheet overlapped, the first sheet and the second sheet are discharged to the loading section by the second transport means. , A sheet ejection device characterized in that it is configured to perform an ejection operation.

According to the present invention, it is possible to improve the loadability of discharged sheets while maintaining productivity.

The schematic diagram of the image formation system which concerns on Embodiment 1 of this disclosure. Sectional drawing of the superimposition processing part which concerns on Embodiment 1. The hardware block diagram of the image formation system which concerns on Embodiment 1. FIG. The functional block diagram of the image formation system which concerns on Embodiment 1. FIG. The figure (a to g) for demonstrating the operation of the superimposition processing unit which concerns on Embodiment 1. FIG. The flowchart which shows the control example of the superimposition processing part which concerns on Embodiment 1. The figure (a-c) for demonstrating the method of controlling the protrusion amount between sheets by the superimposition processing unit which concerns on Embodiment 1. FIG. The figure (a-d) for demonstrating the method of controlling the protrusion amount between sheets by the superimposition processing unit which concerns on Embodiment 2. FIG. The functional block diagram of the image formation system which concerns on Embodiment 2.

Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a schematic view of the image forming system 1S according to the first embodiment as viewed from the front side. The image forming system includes an image forming apparatus 1 that forms an image on a sheet, a sheet processing apparatus 4 that processes an image formed by the image forming apparatus 1, and a sheet that is conveyed from the image forming apparatus 1 to the sheet processing apparatus 4. A relay unit 14 and an image reading device 2 are provided. Sheets that are recording media include paper such as plain paper and thick paper, sheet materials with surface treatment such as plastic film, cloth, and coated paper, and sheet materials with special shapes such as envelopes and index paper. Various sheets of different sizes and materials can be used. Hereinafter, the simple operation of each device constituting the image forming system 1S will be described, and then the operation of the sheet processing device 4 will be described in detail.

The image forming apparatus 1 includes an electrophotographic image forming unit 8 as an image forming means, and a feeding device 6 for feeding the image forming unit 8 one sheet at a time. The image forming unit 8 is integrally composed of a photosensitive drum 9 which is an image carrier (electrophotographic photosensitive member), and a charger and a developing device for executing an electrophotographic process by acting on the photosensitive drum 9. It is a cartridge. A scanner unit 15 as an exposure means is arranged above the image forming unit 8, and a transfer roller 10 as a transfer means is arranged at a position facing the photosensitive drum 9. A fixing device 11, a discharge roller 12a, and a reversing roller 12b are arranged above the transfer roller 10. The fixing device 11 has a heat fixing type configuration, and includes, for example, a tubular film, a heater unit having a heater and arranged inside the film, and a pressure roller pressed against the heater via the film.

A plurality of feeding devices 6 for feeding sheets are arranged below the image forming unit 8. Each feeding device 6 has a cassette 6a as a storage unit (storage, storage means) for storing a plurality of sheets, and a feeding unit 6b for feeding one sheet from the cassette 6a one by one.

When the image forming apparatus 1 executes an image forming operation, the surface of the photosensitive drum 9 is uniformly charged by the charging device in the image forming unit 8, and the scanner unit 15 emits laser light onto the surface of the photosensitive drum 9 based on the image information. To write an electrostatic latent image. This electrostatic latent image is developed (visualized) by toner as a developer supplied from the developer, and a toner image is formed on the surface of the photosensitive drum 9.

In parallel with the operation of the image forming unit 8, sheets are fed one by one from the cassette 6a by the feeding unit 6b in any of the feeding devices 6, and are conveyed toward the registration roller 7. After correcting the skew of the sheet, the registration roller 7 feeds the sheet to the transfer section between the photosensitive drum 9 and the transfer roller 10 at the timing synchronized with the formation of the toner image by the image forming section 8. Then, the toner image is transferred from the photosensitive drum 9 to the sheet in the transfer unit.

The sheet that has passed through the transfer unit is sent to the fixing device 11. In the fixing device, the toner on the sheet is heated and pressurized while the sheet is sandwiched between the film and the pressure roller and passes through the fixing nip (the nip portion of the heater unit and the pressure roller), so that the toner image is formed. Settle on the sheet.

In the case of single-sided printing, the sheet that has passed through the fixing device 11 is discharged from the image forming device 1 by the discharge roller 12a and received by the relay unit 14. In the case of double-sided printing, the sheet on which the toner image is formed on the first surface and has passed through the fixing device 11 is guided by the reversing roller 12, switched back by the reversing roller 12, and re-registered via the reconveying path 13. It is transported to 7. Then, after an image is formed on the second surface opposite to the first surface by passing through the transfer unit and the fixing device 11, the sheet is delivered to the relay unit 14 by the discharge roller 12a.

An image reading device 2 is attached to the upper part of the image forming device 1. The image reading device 2 includes a reading sensor 2s that reads image information from the document sheet, and a document transporting unit that transports the document sheet to the scanning sensor 2s one by one. The image forming apparatus 1 can execute both a copying operation that forms an image based on the image information acquired by the image reading device 2 and a printing operation that forms an image based on the image information received from the outside.

In the present embodiment, the relay unit 14 is provided in the space between the image forming device 1 and the image reading device 2 (also referred to as an in-body discharge space) in the vertical direction (vertical direction when the image forming system 1S is installed on a horizontal plane). Have been placed. The relay unit 14 views the sheet discharged from the image forming apparatus 1 toward the sheet processing apparatus 4 installed side by side with the image forming apparatus 1 on the same installation surface as the image forming apparatus 1 from the front side. Transport in a substantially horizontal direction. A seat sensor 52 is arranged in the relay unit 14 as a detection means for detecting the passage of the seat. The sheet sensor 52 is, for example, a reflective photo sensor that irradiates infrared light into the transport path, detects the reflected light from the sheet passing through the transport path, and determines the presence or absence of the sheet. Although the image forming system 1S having the relay unit 14 is illustrated here, the sheet may be directly delivered from the image forming apparatus 1 to the sheet processing apparatus 4.

Further, the image forming apparatus 1 is provided with a display unit 5 (operation unit, operation display unit) which is a user interface of the image forming system 1S. The display unit 5 has a function of displaying the operating status of the system such as jams and failures, replacement of consumables in the device, removal of jam sheets, and other operations required by the user. Further, the user can operate the touch panel function of the display of the display unit 5, the numeric keypad, and the like to make various settings and instructions to the image forming system 1S.

The configuration of the image forming apparatus is not limited to the direct transfer method shown in FIG. 1, and may be an intermediate transfer method in which the toner image formed by the image forming unit is transferred to the sheet via the intermediate transfer body. A color image forming apparatus using a plurality of image forming units may be used. Further, the image forming mechanism is not limited to the electrophotographic method, and for example, an inkjet type printing unit or an offset printing mechanism may be adopted.

(Sheet processing equipment)
The sheet processing device 4 has a sheet processing unit 71 that processes the sheet, and has a function of discharging the processed sheet received from the image forming apparatus 1 as a product. Further, the sheet processing device 4 can also discharge the sheet received from the image forming device 1 as a deliverable without performing the binding process.

The sheet processing apparatus 4 is provided with a receiving path 81, an internal discharge path 82, a first discharge path 83, and a second discharge path 84 as transport paths for transporting sheets. Further, the sheet processing device 4 has a device main body 4A (a housing provided with a receiving path 81, an internal discharging path 82, a first discharging path 83, and a second discharging path 84 inside) as a discharging destination for discharging the sheet. An upper discharge tray 25 and a lower discharge tray 37 protruding from the outside are provided. The receiving path 81 is a transport path for receiving and transporting the sheet from the image forming apparatus 1, and the internal discharge path 82 is a transport path for transporting the sheet toward the sheet processing unit 71. The first discharge path 83 is a transport path for discharging the sheet to the upper discharge tray 25, and the second discharge path 84 is a transport path for discharging the sheet to the lower discharge tray 37. As described above, in the present embodiment, the receiving path 81 and the first discharging path 83 form a first transport path toward the upper discharge tray 25 as a loading section (first loading section), and branch from the first transport path. An internal discharge path 82 is provided as the second transport path. Further, a second discharge path 84 is provided as a third transport path from the sheet processing unit 71 to the lower discharge tray 37 as the second loading unit.

An inlet roller 21, a pre-branch roller 22, and an inlet sensor 27 are arranged in the acceptance path 81. A discharge reversing roller 24, which is a reversing transport unit, is arranged in the first discharge path 83. An inner discharge roller 26, an intermediate transfer roller 28, a kicking roller 29, and an intermediate pre-loading sensor 38 are arranged in the inner discharge path 82. A bundle discharge roller 36 is arranged in the second discharge path 84. The pre-branch roller 22 is the first transport means of the present embodiment, the discharge reversing roller 24 is the second transport means of the present embodiment, and the inner discharge roller 26 is the third transport means of the present embodiment. The inlet roller 21, the pre-branch roller 22, the discharge reversing roller 24, the inner discharge roller 26, the intermediate transport roller 28, the kicking roller 29, and the bundle discharge roller 36 abut on the outer peripheral surface of the nip portion for sandwiching and transporting the sheet. A pair of rollers to form.

Both the inlet sensor 27 and the intermediate loading sensor 38 detect the passage of the sheet at a predetermined detection position in the transport path in the sheet processing device (that is, output a detection signal according to the passage of the sheet). Is an example of. As the inlet sensor 27 and the intermediate loading sensor 38, for example, a reflective photo sensor that irradiates infrared light into the transport path and detects the reflected light from the sheet passing through the transport path to determine the presence or absence of the sheet is used. be able to. As the sheet detecting means, a configuration may be used in which a flag protruding in the transport path is arranged and a photoelectric sensor such as a photointerruptor detects that the flag is rotated by being in contact with the sheet.

Hereinafter, the sheet transport path in the sheet processing device 4 will be described. The sheet conveyed 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 is conveyed to the pre-branch roller 22 through the acceptance path 81. The inlet sensor 27 detects the seat at the detection position between the inlet roller 21 and the pre-branch roller 22. The pre-branch roller 22 conveys the sheet received from the inlet roller 21 toward the first discharge path 83.

The pre-branch roller 22 accelerates the sheet transfer speed to a speed higher than the transfer speed of the relay unit 14 at a predetermined timing after the inlet sensor 27 detects the passage of the rear end of the sheet. Further, the sheet transfer speed by the inlet roller 21 may be set higher than that of the relay unit 14, and the transfer speed may be accelerated by the inlet roller 21 upstream of the pre-branch roller 22. In this case, it is preferable to install a one-way clutch between the transfer roller of the relay unit 14 and the motor that drives the transfer roller so that the transfer roller spins even if the seat is pulled by the inlet roller 21.

When the discharge destination of the sheet is the upper discharge tray 25, the discharge reversing roller 24 discharges the sheet received from the pre-branch roller 22 to the upper discharge tray 25. In this case, the discharge reversing roller 24 decelerates to a predetermined discharge speed at a predetermined timing after the rear end of the sheet passes through the pre-branch roller 22.

When the discharge destination of the sheet is the lower discharge tray 37, the discharge reversing roller 24 switches back the sheet received from the pre-branch roller 22 and conveys the sheet to the inner discharge path 82. That is, the discharge reversing roller 24 conveys the sheet toward the outside of the sheet processing device 4 in the discharge direction, reverses the rotation direction before the rear end of the sheet in the discharge direction passes through the discharge reversing roller 24, and reverses the sheet. Transport in the direction. A check valve 23 is provided at the branch portion (between the pre-branch roller 22 and the discharge reversing roller 24) where the inner discharge path 82 branches from the receiving path 81 and the first discharge path 83 on the upstream side of the discharge reversing roller 24 in the discharge direction. Is placed. The check valve 23 has a function as a guide (regulatory member) for restricting the seat switched back by the discharge reversing roller 24 from flowing back to the receiving path 81. In other words, the discharge reversing roller 24 performs switchback transfer by reversing the transfer direction of the sheet after the rear end of the sheet in the discharge direction has passed through the check valve 23.

The inner discharge roller 26, the intermediate transfer roller 28, and the kicking roller 29 arranged in the inner discharge path 82 sequentially deliver the sheets received from the discharge reversal rollers 24 and convey them to the sheet processing unit 71. The intermediate loading pre-sensor 38 detects a seat between the intermediate transport roller 28 and the kicking roller 29. The intermediate loading sensor 38 is, for example, a reflective photosensor that irradiates infrared light into the transport path, detects the reflected light from the sheet passing through the transport path, and determines the presence or absence of the sheet.

Here, the sheet processing device 4 has a superimposition processing unit 4B including an discharge reversing roller 24 and an inner discharge roller 26, and a plurality of sheets conveyed one by one from the image forming apparatus 1 are superposed by the superimposition processing unit 4B. It is possible to execute the operation of superimposing. The superimposition processing unit 4B of the present embodiment holds the first sheet conveyed through the acceptance pass 81 in the inner discharge path 82 by the discharge reversing roller 24 and the inner discharge roller 26, and then holds the acceptance pass 81. The operation of superimposing on the second sheet to be transported is performed. The superimposition processing unit 4B has a function of discharging the stacked sheets to the upper discharge tray 25 (superimposition discharge) and a function of transporting the superposed sheets to the sheet processing unit 71 (buffer function). The detailed configuration and operation of the superimposition processing unit 4B will be described later.

The sheet processing unit 71 aligns a plurality of sheets received from the internal discharge path 82, and then executes a binding process at a predetermined position of the sheet bundle. The sheet processing unit 71 has a stapler 50 as a processing means, and an intermediate loading upper guide 31 and an intermediate loading lower guide 32 constituting an intermediate loading unit (processing tray) on which the sheets to be processed are loaded.

A vertical alignment reference plate 39 as a reference member is arranged at the most downstream portion of the sheet processing unit 71 in the transport direction of the kick roller 29, and the sheet bundle end portion in the transport direction is abutted against the vertical alignment reference plate 39 in the vertical direction of the sheet bundle. The position in the transport direction) is aligned. Downstream of the holding guide 56, a half-moon roller 33 rotatably supported by the intermediate loading guide 31 is provided.

The half-moon roller 33 is a moving member (paddle member, transport member) for abutting the sheet that has passed through the kicking roller 29 against the vertical alignment reference plate. After the rear end of the sheet passes through the intermediate loading sensor 38, the half-moon roller 33 conveys the sheet toward the vertical alignment reference plate 39 at a predetermined timing. The contact pressure of the half-moon roller 33 with respect to the sheet is adjusted so as to slip on the sheet when the sheet is in contact with the vertical alignment reference plate 39. A flexible pressing guide 56 is fixed to the intermediate loading guide 31 and presses the sheet in the sheet processing section 71 downward with a predetermined pressing force to regulate the floating of the sheet. Further, downstream of the kicking roller 29, a bundle holder that suppresses lifting of the seat rear end so that the rear end of the seat already loaded on the seat processing unit 71 and the tip of the succeeding seat discharged by the kicking roller 29 do not interfere with each other. The flag 30 is rotatably supported.

When the matching of a predetermined number of sheets (a plurality of sheets that become a part of the deliverable after processing) is completed on the intermediate loading unit, the stapler 50 performs the binding operation. Then, the bundle discharge guide 34 as an extrusion member driven by the guide drive unit 35 moves from the standby position in FIG. 1 toward the bundle discharge roller 36 (bundle discharge direction), so that the seat is seated from the intermediate loading unit. Extrude a bunch. The bundle discharge direction is the direction opposite to the seat discharge direction to the intermediate loading portion by the kick roller 29. When the tip 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 standby position again. The bundle discharge roller 36 as the discharge means (fourth transport means) discharges the sheet bundle received from the bundle discharge guide 34 to the lower discharge tray 37.

Both the upper discharge tray 25 and the lower discharge tray 37 can be moved up and down with respect to the housing of the sheet processing device 4. Sheet presence / absence sensors 51 and 53 for detecting the presence / absence of a sheet on the tray are arranged in each of the upper discharge tray 25 and the lower discharge tray 37. The sheet presence / absence sensors 51 and 53 are reflective photo sensors that determine the presence / absence of a sheet by, for example, irradiating infrared light above the tray loading surface and detecting the reflected light from the sheet. Further, the sheet processing device 4 includes a sheet surface detection sensor that detects the upper surface position (sheet loading height) of the sheet in the upper discharge tray 25 and the lower discharge tray 37.

When the seat surface detection sensor detects the seat, the corresponding upper discharge tray 25 or lower discharge tray 37 tray descends in the A2 and B2 directions. Further, when the sheet presence / absence sensors 51 and 53 detect that the sheet of the upper discharge tray 25 or the lower discharge tray 37 has been removed, the tray is raised in the A1 and B1 directions. The upper discharge tray 25 and the lower discharge tray 37 are controlled to move up and down according to the load capacity of the sheets so that the upper surface of the loaded sheets is located on the lower side in the vertical direction from the discharge reversing roller 24 or the bundle discharge rollers 36. .. In the present embodiment, the upper discharge tray 25 as the first loading part and the lower discharging tray 37 as the second loading part are controlled to be raised and lowered by motor drive, respectively, but for example, an urging means such as a spring. It may be configured to be able to move up and down.

The stapler 50 is an example of processing means, and may be provided with, for example, a sorting mechanism for sorting sheets and a center-folding processing unit for center-folding and binding a plurality of sheets.

(Superimposition processing unit)
FIG. 2 shows an enlarged view of the superimposition processing unit 4B. The sheet transport path (acceptance path 81) between the inlet roller 21 and the pre-branch roller 22 is formed by the inlet upper guide 40 and the inlet lower guide 41. The sheet transport path (inner discharge path 82) between the inner discharge roller 26 and the intermediate transport roller 28 is formed by the inner discharge upper guide 46 and the inner discharge lower guide 47. The transport guide that guides the sheet between the pre-branch roller 22 and the discharge reversing roller 24 from the same side as the inlet guide 40 is referred to as the reversing upper guide 42. Further, a transport guide for guiding the sheet between the discharge reversing roller 24 and the inner discharge roller 26 from the same side as the inner discharge lower guide 47 is referred to as a reversing lower guide 43. The first discharge path 83 is formed by an inverted upper guide 42 and an inverted lower guide 43.

The sheet conveyed by the inlet roller 21 is guided to the pre-branch roller 22 by the inlet upper guide 40 and the inlet lower guide 41. An entrance sensor 27 is arranged on the entrance guide 40. As the entrance sensor 27, a reflective photo sensor that determines the presence or absence of the sheet at the detection position by irradiating infrared light toward the receiving path 81 and detecting the reflected light from the sheet can be used. In this case, in the portion of the guide under the entrance 41 facing the inlet sensor 27, a hole having a size larger than the diameter of the spot light of the inlet sensor 27 is provided so that infrared light is not reflected when the sheet does not pass through. prepare.

A check valve 23 is arranged downstream of the pre-branch roller 22 at a portion where the receiving path 81 and the inner discharge path 82 branch from the first discharge path 83. The check valve 23 is rotatably supported by the internal discharge guide 46 via the rotation shaft 23a. Further, the backflow prevention valve 23 has a position (position in FIG. 2) in which the tip end portion of the backflow prevention valve 23 overlaps with the reversing upper guide 42 when viewed from the axial direction (seat width direction) of the rotary shaft 23a by a spring (not shown). It is always urged toward C2 (clockwise in the figure). Further, the spring constant of the spring is such that when the sheet sent out from the pre-branch roller 22 comes into contact with the check valve 23, the check valve 23 counterclockwise in the C1 direction against the urging force of the spring (counterclockwise in the figure). It is set to a size that allows it to rotate in the (clockwise direction) direction. Therefore, the check valve 23 allows the sheet conveyed from the pre-branch roller 22 toward the discharge reversing roller 24 to pass through. Further, when the rear end of the seat in the receiving path 81 passes through the check valve 23, the check valve 23 rotates in the C2 direction to regulate the backflow of the seat from the discharge reversing roller 24 to the pre-branch roller 22. ..

The discharge reversing roller 24 is composed of an upper roller 24a and a lower roller 24b. In the present embodiment, the driving force is input to both the upper roller 24a and the lower roller 24b, and the rotations of the upper roller 24a and the lower roller 24b are always synchronized.

The discharge reversing roller 24 is configured to be able to perform contact (close operation) and separation (open operation) by the plunger solenoid 45. Specifically, one end of the separation lever 44 is connected to the roller shaft of the upper roller 24a, and the separation lever 44 is rotatably supported about the lever fulcrum shaft 44a with respect to the reversing upper guide 42. The solenoid connecting shaft 44b provided at the other end of the separation lever 44 is connected to the plunger of the plunger solenoid 45.

When the plunger solenoid 45 is energized, the plunger is attracted in the D1 direction by the magnetic force, the separation lever 44 rotates in the E1 direction, and the discharge reversing roller 24 is in a separated state (a state in which the nip portion of the roller pair is opened). When the energization of the plunger solenoid 45 is stopped, the upper roller 24a abuts on the lower roller 24b due to the urging force of the pressure spring 48 connected to the roller shaft of the upper roller 24a, and the discharge reversing roller 24 is in a contact state (nip portion). Is closed). At this time, as the upper roller 24a moves, the separation lever 44 rotates in the E2 direction, and the plunger of the plunger solenoid 45 moves in the D2 direction. The mechanism for opening and closing the discharge reversing roller 24 may be, for example, a mechanism for swinging the separation lever 44 by a cam rotated by the driving force of the motor.

The inner discharge roller 26 is a roller pair adjacent to the discharge reversing roller 24 in the sheet transport direction in the inner discharge path 82, and is a roller pair capable of forward rotation and reverse rotation. That is, the inner discharge roller 26 is in the direction from the discharge reversing roller 24 toward the sheet processing unit 71 (hereinafter referred to as the G1 direction) and the direction from the sheet processing unit 71 toward the discharge reversing roller 24 (hereinafter referred to as the G2 direction). ) Can be transported to any of the sheets.

(Hardware configuration)
Next, the hardware configuration of the image forming system 1S according to the present embodiment will be described with reference to FIG. FIG. 3 is a diagram showing a part mainly related to the configuration of the sheet processing apparatus 4 in the hardware configuration in the image forming system 1S. The video controller 601 controls the entire image forming system 1S including the image forming apparatus 1 and the sheet processing apparatus 4, and the engine control unit 602 controls the image forming apparatus 1.

The main control unit 603 controls the sheet processing device 4. The signal line 604 is a signal line for serial command transmission from the video controller 601 to the engine control unit 602, and the signal line 605 is a signal line for transmitting commands from the video controller 601 to the main control unit 603 by serial communication. The signal line 606 is a signal line for serial status transmission that transmits status data from the engine control unit 602 to the video controller 601 and the signal line 607 from the main control unit 603 to the video controller 601 in response to a command. .. In performing the image forming operation, the video controller 601 controls by transmitting a serial command to the engine control unit 602 and the main control unit 603 and receiving status data from the engine control unit 602 and the main control unit 603. It is carried out. In this way, when a plurality of devices are connected and the image forming system 1S operates, the video controller 601 manages the control and state of each device, and maintains the consistency of operation between the devices.

The main control unit 603 includes a CPU 608 that controls various operations of the sheet processing device 4, and a RAM 609 that temporarily stores control data required for the operation of the sheet processing device 4. The main control unit 603 further includes a non-volatile ROM 610 that stores a control table necessary for the operation of the program and the sheet processing device 4. The main control unit 603 inputs / outputs control signals to the communication means 611 that performs communication processing with the video controller 601, the system timer 612 that generates the timing required for various controls, and various units in the sheet processing device 4. It also has an I / O port 613. The main control unit 603 is a control IC in which these elements are connected via a bus 614.

The input signals from the seat presence / absence sensors 51 and 53 of the inlet sensor 27, the upper discharge tray 25 and the lower discharge tray 37 are transmitted to the main control unit 603 via the input circuits 615, 626, 628. Further, the control signal from the main control unit 603 is sent to the inlet motor 641, the pre-branch motor 642, the discharge reversing motor 643, the internal discharge motor 644, or the plunger solenoid 45 via the drive circuit 618, 619, 620, 621, 623. Be transmitted. As a result, the drive of each actuator is controlled.

(Functional block)
Next, the functional block of this embodiment will be described with reference to FIG. The main control unit 603 of FIG. 4 has a function of executing the sheet transfer operation of the sheet processing device 4. The main control unit 603 has at least the functions of the communication means 611, the system timer 612, the sheet transfer control means 701, the sensor control means 720, the motor control means 721, and the solenoid control means 722.

The sensor control means 720 is a means for inputting signals from the sheet presence / absence sensor 51 of the inlet sensor 27 and the upper discharge tray 25 to the sheet transfer control means 701. The sheet transfer control means 701 is composed of a superimposition transfer control means 711 and a number control means 712. The sheet transfer control means 701 controls the motor control means 721 and the solenoid control means 722 based on the input of the sensor control means 720 to realize the operations of the superimposition processing unit 4B, the upper discharge tray 25, and the lower discharge tray 37. .. The superimposition transfer control means 711 mainly controls the sheet transfer to the superimposition processing unit 4B and the upper discharge tray 25 while managing the position of the sheet based on the input of the sensor control means 720.

The number control means 712 manages the number of sheets to be overlapped in the superimposition processing unit 4B when executing a job of continuously forming an image on a plurality of sheets. Based on the maximum number of sheets that can be superposed by the superposition processing unit 4B (superpositionable number of sheets), the current number of superposed sheets, and the sheet information, the number control means 712 sets the superposed sheets on the upper discharge tray 25 or It is determined whether to transport the sheet to the sheet processing unit 71 or to continuously superimpose the subsequent sheets.

The drive target of the inlet motor 641 is the inlet roller 21, the drive target of the pre-branch motor 642 is the pre-branch roller 22, and the drive target of the discharge reversal motor 643 is the discharge reversal roller 24. The drive target of the inner discharge motor 644 is the inner discharge roller 26, and the drive target of the plunger solenoid 45 is the separation lever 44. Details of the operation of these drive targets will be described later.

(Superimposed discharge operation)
5 (a) to 5 (f) will be used to describe an outline of an operation (superposition discharge operation) in which the superposition transfer control means 711 superimposes and discharges a plurality of sheets by the superposition processing unit 4B. Hereinafter, among the sheets to be subjected to the superimposed discharge operation, the sheet transferred from the image forming apparatus 1 to the sheet processing device 4 (first sheet) is referred to as the sheet S1 and is conveyed to the second sheet. The thing (second sheet) is referred to as sheet S2. Further, the transport speed of the pre-branch roller 22, the discharge reversing roller 24, and the inner discharge roller 26 before acceleration (transport speed in the relay unit 14) is set to V1, and the transport speed after acceleration is set to V2.

Roughly speaking, in the superimposed discharge operation, the sheet S1 received from the pre-branch roller 22 (first transport unit) is inverted by the discharge reversing roller 24 (second transport unit), and the inner discharge roller 26 (third transport unit) is used. (Figs. 5 (a) to (d)). Next, the sheet S1 is discharged to the inner discharge roller 26 (third transport unit) based on the fact that the inlet sensor 27 (detection unit) emits a detection signal in response to the sheet S2 transported following the sheet S1. It is conveyed toward the reversing roller 24 (second transport unit) (FIG. 5 (e)). Then, with the ends of the sheet S1 and the sheet S2 aligned in the transport direction and the sheets S1 and the sheet S2 stacked, the sheet S1 and the sheet S2 are loaded on the upper discharge tray 25 (loading) by the discharge reversing roller 24 (second transport section). (Fig. 5 (f)).

FIG. 5A: The pre-branch roller 22 and the discharge reversing roller 24 are accelerated from the speed V1 to the speed V2 at the timing when the rear end of the preceding sheet S1 passes through the inlet sensor 27. By accelerating the transport speed of the sheet S1, even if the image forming apparatus 1 is a high-performance machine having a high throughput, the sheet spacing required for switchback is secured between the sheet S1 and the subsequent sheet S2. Can be done. However, if the sheets S1 and S2 do not collide, the transfer speed may not be accelerated by the inlet sensor 27. In that case, the transfer speed in the superimposition processing unit 4B may be unified by V1. Further, at the time of FIG. 5A, the discharge reversing roller 24 conveys the sheet S1 in the F2 direction.

FIG. 5B: After the rear end of the seat S1 passes through the inlet sensor 27, the seat S1 is temporarily stopped at the timing when it moves a predetermined distance and passes through the check valve 23. The "predetermined distance" is a distance at which the rear end of the seat S1 in the F2 direction passes through the check valve 23 and the rear end does not reach the nip portion of the discharge reversing roller 24.

FIG. 5 (c): The discharge reversing roller 24 changes the rotation direction and conveys the sheet S1 in the F1 direction at a speed V2. The drive of the inner discharge roller 26 is started before the tip 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.

FIG. 5D: The sheet S1 is conveyed at a position where the sheet S1 is sandwiched between the inner discharge rollers 26 and the tip of the sheet S1 in the G1 direction (F1 direction) passes through the inner discharge roller 26 and is conveyed by a predetermined amount. Stop. The "predetermined amount" is shorter than the distance at which the tip of the sheet S1 reaches the intermediate transfer roller 28. Further, the upper roller 24a of the discharge reversing roller 24 moves in the E1 direction by the separation lever 44 at the timing when the sheet S1 is sandwiched by the inner discharge roller 26, and separates from the lower roller 24b. The discharge reversing roller 24 is driven so that the tip of the subsequent sheet S2 is separated from the discharge reversing roller 24 before reaching the discharge reversing roller 24.

FIG. 5 (e): After the rear end of the succeeding sheet S2 passes through the inlet sensor 27, the pre-branch roller 22 and the discharge reversing roller 24 are accelerated to the speed V2 in the same manner as the sheet S1 of the preceding sheet. When the rear end of the sheet S2 passes through the inlet sensor 27 and T_wait elapses for a predetermined time, the inner discharge roller 26 starts rotating again toward the discharge reversing roller 24, and the sheet S1 is conveyed in the G2 direction. The predetermined time T_wait will be described later. At the timing when the relative speeds of the sheet S1 and the sheet S2 become equal, the upper roller 24a of the discharge reversing roller 24 is driven in the E2 direction and comes into contact with the lower roller 24b, and the discharge reversing roller 24 simultaneously sandwiches the sheet S1 and the sheet S2. .. At this point, the tip of the sheet S1 and the tip of the sheet S2 in the F2 direction are aligned. Further, the rotation speed of the discharge reversing roller 24 is adjusted so as to be equal to the speed V2 which is the transport speed of the sheets S1 and the sheet S2 before the sheets S1 and the sheet S2 are sandwiched.

FIG. 5 (f): When the rear end of the seat S2 passes through the check valve 23, the seat S1 and the seat S2 become a seat bundle S'in which the positions of the front end and the rear end in the F2 direction are aligned. When the discharge destination of the sheet bundle S'is set to the upper discharge tray 25, the sheet bundle S'is discharged to the upper discharge tray 25 by the discharge reversing roller 24 while maintaining the speed V2.

FIG. 5 (g): On the other hand, when the discharge destination of the sheet bundle S'is set to the lower discharge tray 37, the rear end of the sheet (here, the sheet S2) finally added to the sheet bundle S'is backflowed. The discharge reversing roller 24 is temporarily stopped when it passes through the prevention valve 23. After that, the sheet bundle S'is conveyed to the sheet processing unit 71 at a speed V2 by the discharge reversing roller 24.

As a result, the operation of superimposing and discharging the two sheets S1 and S2 while aligning them in the superimposition processing unit 4B (superimposition discharge operation) is completed. When the image forming operation is continuously performed on a large number of sheets, the two sheet bundles are loaded on the upper discharge tray 25 by repeating the above-mentioned superimposed discharge operation.

Here, the advantages of the present embodiment will be described as compared with the case where the sheets S1 and S2 are ejected one by one without performing the superimposed ejection operation. When the sheets S1 and S2 are discharged one by one, the position and posture are disturbed until the sheets S1 and S2 that have passed through the discharge reversing roller 24 land on the upper surface of the upper discharge tray 25 or the upper surface of the sheet on the upper discharge tray 25. there is a possibility. This is because the seats S1 and S2 receive air resistance and fall while moving back and forth and left and right when viewed from above.

On the other hand, in the present embodiment, since the sheets S1 and S2 are ejected in a state of being overlapped with the positions in the sheet transport direction aligned in advance, the positions and postures of the sheets S1 and S2 are less likely to be disturbed. Comparing the sheet bundles ejected by the superimposed ejection operation and the sheets ejected one by one, the projected area of the sheets (bundles) seen from above is the same, while the weight of the sheet bundle is 2 of one sheet. This is because it is doubled and is not easily affected by air resistance. Therefore, in order to improve the productivity of the image forming system 1S and the productivity of the sheet processing apparatus 4, even when the sheet ejection speed by the ejection reversing roller 24 is high, it is possible to suppress the decrease in the sheet loading capacity. .. That is, according to the present embodiment, it is possible to improve the loadability of the sheet in the upper discharge tray 25 while maintaining the productivity. Further, in the present embodiment, as compared with the method in which an intermediate loading unit such as the sheet processing unit 71 is prepared and the sheets are overlapped and aligned and then discharged, the sheets are overlapped and discharged in a simple and compact configuration. can do.

In the present embodiment, the upper discharge tray 25 as a loading portion protrudes to the outside of the apparatus main body 4A, and the sheet discharged above the upper discharge tray 25 by the discharge reversing roller 24 is other than the discharge reversing roller 24. It falls on the upper discharge tray 25 due to gravity without being transported to the transport unit. Even in such a configuration that is relatively susceptible to the influence of air resistance, it is possible to improve the loadability of the sheet in the upper discharge tray 25 by executing the superimposed discharge operation.

(Overlapping discharge operation of 3 or more sheets)
Although the transfer of two sheets has been described above, in the sheet processing apparatus 4 of the present embodiment, the superposition processing unit 4B aligns three or more sheets and superimposes them on each other to discharge them to the upper discharge tray 25. Can perform actions.

When performing the superposition discharge operation for three sheets, first, the two sheets S1 and S2 are overlapped by the above-mentioned procedure using FIGS. 5 (a) to 5 (f), and then FIG. 5 (f). The discharge reversing roller 24 is reversed again from the state of the above, and the sheet bundle S'is conveyed in the G1 direction. Then, while performing the operation performed on the sheet S1 in FIGS. 5 (c) to 5 (f) on the sheet bundle S', the operation performed on the sheet S2 in FIGS. 5 (c) to 5 (f) was performed. The operation is performed on the third sheet S3 (third sheet).

As a result, after the sheet bundle S'is temporarily stopped while being held by the inner discharge roller 26 of the inner discharge path 82, a predetermined time T_wait has elapsed from the detection of the rear end of the third sheet S3 by the inlet sensor 27. The inner discharge roller 26 conveys the sheet bundle S'in the G2 direction. After that, when the discharged reversing roller 24 that has been opened is closed, the three sheets S1, S2, and S3 are simultaneously sandwiched between the discharged reversing rollers 24. When the rear end of the sheet S3 passes through the check valve 23, a sheet bundle in which the positions of the front end and the rear end of the three sheets S1, S2 and S3 are aligned is formed.

When the number of sheets in the superimposed discharge operation is three, the bundle of sheets is discharged as it is in the G2 direction by the discharge reversing roller 24 and is loaded on the upper discharge tray 25. When the number of sheets in the overlapping discharge operation is four or more, the discharge reversing roller 24 again conveys the sheet bundle in the G1 direction and repeats the same operation as in FIGS. 5 (c) to 5 (f) to superimpose the sheets. You can increase the number of sheets.

The number control means 712 manages the number of sheets to be overlapped by the superimposition processing unit 4B based on the information on the number of sheets that can be superposed by the superimposition processing unit 4B and the sheets to be conveyed. That is, the number control means 712 determines whether the sheet conveyed to the superimposition processing unit 4B is immediately conveyed (discharged) toward the upper discharge tray 25 or the sheet processing unit 71, or is overlapped with the subsequent sheet.

As an example of the determination method, when the number of sheets that can be superimposed by the superimposition processing unit 4B is N, the number control means 712 creates a bundle of N-1 sheets and discharges them to the upper discharge tray 25. That is, when the control means of the present embodiment executes a job of ejecting a plurality of sheets to the loading section, the control means so as to eject the plurality of sheets to the loading section in a state of being stacked for each preset number of sheets. , The superimposed discharge operation as the discharge operation is repeatedly executed. Furthermore, if it is determined that the Nth sheet is the final sheet in the job, the number of sheets to be stacked is set to N to prevent the Nth sheet from being discharged to the upper discharge tray 25 as one sheet. ing.

As a specific example, in the configuration example of the present embodiment, the number of superimposition processing units 4B that can be superposed is five. In this case, the number control means 712 repeatedly executes the superimposed discharge operation on the four sheets, and loads the sheet bundle composed of the four sheets on the upper discharge tray 25. Here, if it is determined that the fifth sheet becomes the final sheet and the final sheet is ejected as one sheet when the superimposed ejection operation for every four sheets is performed to the end, the five sheets are superimposed and ejected so as to include the final sheet. The sheet is discharged to the upper discharge tray 25 by the operation. If the final sheet is overlapped with another sheet even if the overlapping ejection operation for every four sheets is performed to the end, the sheet bundle is ejected to the upper ejection tray 25 when the sheet bundle including the final sheet is formed. ..

In other words, when the sheet number control means 712 executes a job of discharging a predetermined number of sheets to the upper discharge tray 25, each of the predetermined number of sheets is always from two or more sheets formed by the superimposed discharge operation. The number of sheet bundles formed by the superimposed discharge operation is changed according to the value of the predetermined number of sheets so that the sheets are discharged to the upper discharge tray 25 while being included in the sheet bundle. Further, in other words, the control means of the present embodiment discharges by the job so that each of the plurality of sheets discharged during the job is discharged to the loading unit in a state of being overlapped with any of the other sheets. The number of sheets to be stacked is changed by the overlapping discharge operation according to the number of sheets. As a result, it is possible to prevent the loadability of the sheet from being lowered due to the sheet being discharged independently to the upper discharge tray 25. The method of controlling the number of sheets in the superimposed ejection operation is not limited to this as long as the sheet can be prevented from being ejected independently. For example, in the above example, the number of sheets in the superimposed ejection operation is four, ... It may be 4 sheets, 3 sheets, or 2 sheets.

(How to find T_wait)
Here, the timing management (the above-mentioned method of obtaining T_wait) performed by the superimposition transfer control means 711 in order to align the sheet tips of the sheets S1 and S2 in the superimposition processing unit 4B will be described.

FIG. 7A shows the positional relationship between the seat S1 and the seat S2 at the moment when the rear end of the seat S2 is detected by the inlet sensor 27. The distance L1 is the distance from the detection position of the inlet sensor 27 to the nip position of the discharge reversing roller 24 (the length measured along the reception path 81 and the first discharge path 83). The distance L2 is the distance from the position where the tip of the sheet S1 after inversion passes through the inner discharge roller 26, then moves by a predetermined distance d1 and stops, to the nip portion of the discharge inversion roller 24 (first discharge path 83 and The length measured along the internal discharge path 82).

Further, in FIG. 7B, the timing at which the sheet S1 starts to be conveyed in the F2 direction (G2 direction) from the state of FIG. 7A and the conveying speed of the sheet S1 becomes equal to the conveying speed of the sheet S2. The positional relationship between the sheets S1 and S2 in the above is shown. At this point, it is assumed that the rear ends of the sheets S1 and S2 in the F2 direction are displaced by the protrusion amount Kt.

7 (c) shows the transition of the speed of the sheets S1 and S2 in the operation shown in FIGS. 7 (a) and 7 (b). In the figure, A shows the moment when the inlet sensor 27 detects the rear end of the seat S2 and starts accelerating the pre-branch roller 22 from the speed V1 to the speed V2 at a constant acceleration as shown in FIG. 7A. .. In the figure, B indicates the timing at which the seat S2 has been accelerated to the speed V2. In the figure, C indicates the timing at which the inlet sensor 27 detects the rear end of the sheet S2 and T_wait elapses for a predetermined time, that is, the timing at which the sheet S1 is started to be conveyed in the G2 direction by the internal discharge roller 26. In the figure, D indicates the timing at which the relative speed (speed difference) between the sheets S1 and the sheet S2 becomes zero as shown in FIG. 7 (b).

Hereinafter, the elapsed time from A to D is referred to as T_Merge. The time T1 represents the time required for the pre-branch roller 22 to accelerate from the speed V1 to the speed V2 (elapsed time from A to B). The time T2 represents the time (elapsed time from B to C) until the inner discharge roller 26 starts rotating after the pre-branch roller 22 accelerates to the speed V2. From the definition of T1, T2, T_wait, T_wait = T1 + T2. The time T3 represents the time (elapsed time from C to D) required for the seat S1 to accelerate at a constant acceleration from the stopped state and reach the speed V2.

From the above description, the distance X2 that the sheet S1 travels from the state of FIG. 7A to the state of FIG. 7B is the distance that the sheet S1 travels from C to D in FIG. 7C. It can be expressed by the following equation (1).
X2 = (V2 × T3) / 2 (1)

Further, the distance X1 that the sheet S2 travels from the state of FIG. 7A to the state of FIG. 7B is the distance that the sheet S2 travels from A to D in FIG. 7C, and the following formula is used. It can be expressed by (2).
X1 = (V1 + V2) x T1 / 2 + V2 x (T2 + T3) (2)

From the positional relationship between the sheets S1 and S2 at the timing of FIG. 7B, the relationship of the following equation (3) is established.
L1-X1 = L2-X2-Kt (3)

Substituting the equations (1) and (2) into the equation (3), expanding and rearranging them gives the following equation (4).
L1-L2 + Kt
= (T1 / 2) x V1 + (T1 / 2 + T2 + T3 / 2) x V2 (4)

By substituting T_wait = T1 + T2 into the above equation (4) and rearranging them, the rear end of the sheet S2 passes through the inlet sensor 27 with respect to the protrusion amount Kt until the sheet S1 is transferred by the internal discharge roller 26. The waiting time T_wait is calculated by the following equation (5).
T_wait = (L1-L2 + Kt) / V2
-(T1 / 2) x V1 / V2 + (T1-T3) / 2 (5)

In order to align the front end and the rear end of the sheets S1 and S2 and superimpose them, the waiting time T_wait may be calculated with Kt = 0 in the above equation (5). By starting the transfer of the sheet S1 by the inner discharge roller 26 based on the calculated T_wait, it becomes possible to form the sheet bundle S'in a state where the front end and the rear end of the sheets S1 and S2 are aligned. That is, the predetermined time (T_wait) from the detection of the sheet S2 by the inlet sensor 27 to the start of the transfer of the sheet S1 by the inner discharge roller 26 is such that the ends of the sheets S1 and S2 are aligned in the discharge reversing roller 24. Is preset to. Further, by using T_wait of the same value when stacking three or more sheets, it is possible to form a sheet bundle in which the front end and the rear end of each sheet are aligned.

(Control example)
Next, an example of the control method of the sheet processing device 4 that realizes the superimposed discharge operation described with reference to FIGS. 5 (a to 5) will be described with reference to the flowchart of FIG. This flow is executed every time the main control unit 603 of the sheet processing device receives a notification from the video controller 601 that one sheet is ejected from the image forming device 1. Unless otherwise specified, each step of this flow shall be executed by the superimposed transfer control means 711 of FIG.

In the following description, the "first sheet" is the sheet that is first conveyed to the sheet processing apparatus 4 among the sheets constituting the sheet bundle to be overlapped in the superimposing processing unit 4B. For example, when four sheets are stacked and discharged to the upper discharge tray 25, it is a sheet (4n + 1st sheet) that is conveyed to the sheet processing device 4 next to the last sheet of the previous sheet bundle. be. Further, the "final sheet" is a sheet (the 4nth sheet in the above example) that has been finally conveyed to the sheet processing device 4 among the sheets constituting the sheet bundle to be overlapped in the superimposition processing unit 4B. be.

Step S101: The inlet roller 21 and the pre-branch roller 22 are started to rotate at a speed V1. Transition to S102. If the inlet roller 21 and the pre-branch roller 22 are already rotating at the speed V1, the rotation is continued.
Step S102: It is determined whether or not the current sheet is the first sheet. In the case of Yes, the transition is made to S103, and in the case of No, the transition is made to S106.

Step S103: The discharge reversing roller 24 is brought into contact with each other, and rotation is started at a speed V1 in the direction (G2 direction) for transporting the first sheet toward the upper discharge tray 25 (see sheet S1 in FIG. 5A). .. Transition to S104.
Step S104: It is determined whether the rear end of the first sheet has passed the inlet sensor 27. In the case of Yes, the transition is made to S105, and in the case of No, the transition is made to S104.
Step S105: The pre-branch roller 22 and the discharge reversing roller 24 are accelerated to a speed V2 (see sheet S1 in FIG. 5A). Transition to S111.

Step S106: It is determined whether the rear end of the current sheet (second and subsequent sheets) has passed the inlet sensor 27. In the case of Yes, the transition is made to S107, and in the case of No, the transition is made to S106.
Step S107: The pre-branch roller 22 and the discharge reversing roller 24 are accelerated to a speed V2. As a result, the transfer speed of the current sheet is accelerated from the speed V1 to V2 (see sheet S2 in FIG. 5D). Transition to S108.
Step S108: It is determined whether or not T_wait has elapsed for a predetermined time from the timing when the rear end of the seat this time passes through the inlet sensor 27. In the case of Yes, the transition is made to S109, and in the case of No, the transition is made to S108.
Step S109: The inner discharge roller 26 is started to rotate again at a speed V2 in the direction (F2 direction) for transporting the sheet toward the discharge reversing roller 24 (see sheet S1 in FIG. 5D). Transition to S110.
Step S110: At the timing when the sheet (bundle) transported to the inner discharge roller 26 and the current sheet transfer speed become equal, the upper roller 24a of the discharge reversing roller 24 is moved in the E2 direction and comes into contact with the lower roller 24b. (See FIG. 5 (e)). As a result, the sheet (bundle) conveyed by the inner discharge roller 26 and the current sheet are simultaneously sandwiched by the discharge reversing roller 24 (see FIG. 5 (e)). Transition to S111.

Step S111: It is determined whether the current sheet is the final sheet. In the case of Yes, the transition is made to S112, and in the case of No, the transition is made to S115.

Step S112: The sheet bundle including the final sheet is discharged to the upper discharge tray 25 (see FIG. 5 (f)). That is, the sheet transfer by the discharge reversing roller 24 and the inner discharge roller 26 started in S107 and S109 is continued, and the upper discharge tray 25 is formed as a bundle of a predetermined number of sheets in which the front end and the rear end of the sheet are aligned together with the current sheet. Discharge to.
Step S113: It is determined whether the rear end of the sheet bundle has passed through the discharge reversing roller 24. In the case of Yes, the transition is made to S114, and in the case of No, the transition is made to S113.
Step S114: The pre-branch roller 22 is decelerated to the speed V1, the discharge reversing roller 24 and the inner discharge roller 26 are stopped, and this flow is terminated. If the sheet this time is also the last sheet in the job (when no more sheets are conveyed from the image forming apparatus 1), the inlet roller 21 and the pre-branch roller 22 are also stopped in S114.

Step S115: It is determined whether the rear end of the seat (seat other than the final seat) of this time has passed through the check valve 23. In the case of Yes, the transition is made to S116, and in the case of No, the transition is made to S115.
Step S116: The discharge reversing roller 24 and the inner discharge roller 26 are temporarily stopped (see sheet S1 in FIG. 5B). Transition to S117.
Step S117: The discharge reversing roller 24 and the inner discharge roller 26 start rotating at a speed V2 in the rotation direction for transporting the sheet (bundle) in the direction after reversing (F1 direction, G1 direction) (FIG. 5 (c). ) Sheet S1). Transition to S118.
Step S118: It is determined whether the tip of the sheet (bundle) has passed through the inner discharge roller 26. In the case of Yes, the transition is made to S119, and in the case of No, the transition is made to S118.
Step S119: The upper roller 24a of the discharge reversing roller 24 is separated from the lower roller 24b. Transition to S120.
Step S120: At a position where the tip of the sheet (bundle) has passed the inner discharge roller 26 and then a predetermined amount has been conveyed, the pre-branch roller 22 is decelerated to a speed V1 and the discharge reversing roller 24 and the inner discharge roller 26 are stopped. , End this flow. As a result, the sheets (bundles) that are the targets of the superimposed discharge operation and are still overlapped with other sheets are held in a state of being sandwiched by the inner discharge rollers 26 (see sheet S1 in FIG. 5 (d)). .. The timing of steps S109, S113, S115, S118 and the like can be determined based on the timing signal of the system timer 612 (FIG. 6). For example, the determination is made based on the operation history of the discharge reversing roller 24 and the inner discharge roller 26 from the time when the rear end of the sheet S1 is detected by the inlet sensor 27.

As described above, according to the present embodiment, when a plurality of sheets continuously conveyed are discharged to the loading section, the edges of the plurality of sheets are aligned and overlapped in the superposition processing section 4B. It becomes possible to discharge. This makes it possible to improve the loadability of the sheet in the loading section while maintaining the productivity. Further, for the purpose of stacking the sheets on the upper discharge tray 25 and discharging the sheets, it is not necessary to arrange the intermediate tray having the sheet matching function in the sheet processing device, so that the cost due to the increase in size and size of the device is required. It is possible to avoid the increase.

In the configuration example of the present embodiment, the maximum number of sheets that can be superposed by the superimposing processing unit 4B (the number of superimposing sheets) has been described as 5, but the specific configuration of the superimposing processing unit 4B and the required number of sheets are required. The number of sheets that can be superimposed can be changed as appropriate according to the performance.

(Buffer operation when processing is performed in the sheet processing section)
When the sheet processing unit 71 processes the sheet, the superposition processing unit 4B of the present embodiment can also operate as a buffer unit that superimposes and holds the sheets received from the image forming apparatus 1 during the execution of the processing. .. By performing the buffer operation, collision of sheets in the sheet processing unit 71 is avoided without reducing the productivity of the image forming apparatus 1, so that the productivity of the image forming system 1S is improved.

When the buffer operation is performed, the operation of the superimposition processing unit 4B is basically the same as the superimposition discharge operation except that the overlapped sheet bundle is conveyed to the sheet processing unit 71 via the internal discharge path 82. That is, in the operations shown in FIGS. 5 (a) to 5 (f), the stacked sheet bundles as shown in FIG. 5 (f) are not discharged to the upper discharge tray 25, but are discharged to the inner discharge roller 26 and the like. It is conveyed to the sheet processing unit 71 via the sheet processing unit 71. Further, after the sheet bundle is conveyed to the sheet processing unit 71 by the buffer operation, the subsequent sheets that do not need to be buffered are switched back one by one by the discharge reversing roller 24 and conveyed to the sheet processing unit 71.

In the buffer operation, the protrusion amount Kt (FIG. 7 (b)) may be set so that the tips (ends) of the overlapped sheets are displaced by a predetermined distance. In that case, if the protrusion amount Kt is set so that the sheet located on the lower side of the sheet processing unit 71 (sheet S1 in FIG. 7B) protrudes further downstream in the sheet transport direction toward the sheet processing unit 71. Suitable. As a result, the half-moon roller 33 can be brought into contact with each sheet of the sheet bundle stacked by the buffer operation, and the matching operation can be effectively performed. In particular, it is preferable that the protrusion amount Kt is larger than the distance from the contact position of the half-moon roller 33 with respect to the sheet to the vertical alignment reference plate 39.

As described above, the superimposition processing unit 4B of the present embodiment has a function of performing a superimposition discharge operation when discharging a sheet to the outside of the sheet processing device 4 without processing by the sheet processing unit 71, and processing by the sheet processing unit 71. It also has the function of buffering the sheet to be applied. As a result, it is possible to reduce the size and cost of the device as compared with the configuration in which two mechanisms for stacking sheets are arranged in order to realize each function.

<Second embodiment>
In the first embodiment, a method of improving the loadability by a superposition discharge operation in which sheets are overlapped and discharged has been described. In the second embodiment, in the superimposed discharge operation described in the first embodiment, the standby position of the sheets to be overlapped is changed according to the length of the sheets in the transport direction. Hereinafter, the elements with the same reference numerals as those of the first embodiment are assumed to have substantially the same configuration and operation as those of the first embodiment, and the description thereof will be omitted.

In the bundle discharging operation described in the first embodiment, the sheet S1 is stopped at which position after the conveying direction of the preceding sheet S1 is reversed by the operation from FIG. 5 (a) to FIG. 5 (d) (FIG. 5). (D)) Think about whether to let it. Hereinafter, the length of the sheet S1 in the transport direction is defined as Ls. Let L2 be the length of the sheet S1 from the nip position of the discharge reversing roller 24 to the end portion S1a of the sheet S1 on the G1 direction side (inner discharge roller 26 side). Let L3 be the length of the sheet S1 from the nip position of the discharge reversing roller 24 to the end portion S1b projecting to the outside of the sheet processing device 4 with respect to the nip position. The relationship of Ls = L2 + L3 is established between Ls, L2, and L3.

As shown in FIGS. 8A and 8B, the length Ls of a sheet having a long transport direction length (for example, an A4 sheet in the long side feed direction) is Ls1, and a sheet having a short transport direction length (for example, a long side) is set to Ls1. Let the length Ls of the A5 sheet in the feed direction be Ls2. Ls1 is an example of the first length and Ls2 is an example of the second length.

In the present embodiment, regardless of whether the length Ls of the sheet S1 is Ls1 or Ls2, the length L3 at which the end portion S1b of the sheet S1 protrudes with respect to the discharge reversing roller 24 is Lmax or less (predetermined value or less). To be. The Lmax, which is a predetermined value, is such that the end portion S1b of the sheet S1 (or the sheet bundle) protruding at the length of Lmax with respect to the nip position of the discharge reversing roller 24 is discharged upward as shown in FIG. 8 (c). A value considered in advance is set so as not to lean against the tray 25. This is because if the end portion S1b of the temporarily stopped sheet S1 leans against the seat S1, the position of the loading sheet St may be disturbed by rubbing against the loading sheet St on the upper discharge tray 25 when the sheet S1 is later discharged.

When the sheet is sandwiched, the discharge reversing roller 24 slightly curves (or undulates) the cross-sectional shape of the sheet along the sheet width direction while the sandwiched sheet is viewed on the downstream side in the sheet discharge direction. ) Is designed. For example, the portion of the upper roller 24a in contact with the sheet (roller) and the portion of the lower roller 24b in contact with the sheet (roller) are staggered in the sheet width direction, and the outer peripheral surfaces of both are partially viewed in the sheet width direction. It is a so-called comb-tooth roller arranged so as to overlap with each other.

As described above, the discharge reversing roller 24 conveys the sheet while giving it a curved shape, so that the end portion S1b of the sheet bundle S'superposed by the superposition discharge operation hangs down as shown in FIG. 8 (d). It is discharged while maintaining a nearly straight posture. Therefore, it is possible to reduce the possibility that the sheet bundle S'is rubbed against the upper surface of the loading sheet St loaded on the upper discharge tray 25 and disturbs the loading property of the loading sheet St.

FIG. 9 shows a functional block diagram of the image forming system 1S according to the present embodiment. Compared with the first embodiment shown in FIG. 4, the superimposed transfer control means 711 is different in that the superposition transfer control means 711 includes the stop position control means 713 in addition to the number control means 712. The stop position control means is a means for controlling the position at which the preceding sheet is temporarily stopped when a plurality of sheets are overlapped by the superimposition processing unit 4B.

The stop position control means 713 determines L2 by the following equation (6) based on the sheet transport direction length Ls acquired from the video controller 601 via the communication means 611.
L2 = Ls-Lmax (6)

The control method of the sheet processing apparatus 4 is basically the same as the method of the first embodiment described with reference to FIG. Here, in the first embodiment, in step S120, the discharge reversing roller 24 and the discharge reversing roller 24 and the position where the tip of the sheet S1 is conveyed by a predetermined amount (predetermined distance d1 in FIG. 7B) after passing through the inner discharge roller 26. The inner discharge roller 26 was stopped. Instead of this, in the present embodiment, after the tip of the sheet S1 passes through the inner discharge roller 26, the sheet S1 is discharged when the sheet S1 is conveyed by the distance d2 corresponding to L2 obtained by the above formula (6). The reversing roller 24 and the inner discharge roller 26 are stopped. This distance d2 is d2 = L2-d4 if the distance from the nip position of the discharge reversing roller 24 to the inner discharge roller 26 is d4, and is a variable whose value changes according to the sheet length Ls. Further, the timing at which the tip of the sheet S1 is conveyed by the distance d2 after passing through the inner discharge roller 26 can be determined based on the timing signal of the system timer 612 (FIG. 6). For example, the determination is made based on the operation history of the discharge reversing roller 24 and the inner discharge roller 26 from the time when the rear end of the sheet S1 is detected by the inlet sensor 27. The timing management (such as the above-mentioned method of obtaining T_wait) performed by the other superimposed transfer control means 711 is the same as that of the first embodiment.

By the method described above, by changing the standby position for suspending the sheet S1 according to the length Ls of the sheet, it is possible to set the protruding length L3 of the sheet S1 at the time of the suspension to a predetermined value Lmax or less. Will be. As a result, in the process of superimposing the sheets S1 and S2 in the superimposing processing unit 4B, the end portion S1b of the sheet S1 temporarily stopped for waiting for the subsequent sheet S2 hangs down, and the loading already loaded on the upper discharge tray 25. It is possible to suppress rubbing against the sheet St. As a result, it is possible to reduce the possibility that the loading sheet St is displaced due to the seat S1 dragging and moving the loading sheet St when the seats S1 and S2 are later ejected. As a result, it is possible to improve the loadability of the ejected sheets for sheets of various sizes. Further, even if the sheet S1 has a curl (curved habit), it is unlikely that the temporarily stopped sheet S1 is significantly curled outside the discharge reversing roller 24, and the end portions S1b are unlikely to be significantly curled when the sheets S1 and S2 are discharged. Can be reduced from the possibility of being curled up.

Depending on the configuration of the device, the range of the value of L2 may be limited. For example, the lower limit of the length of L2 may be set so that the transport of the sheet S1 is temporarily stopped after the end portion S1a of the sheet S1 is sandwiched by the inner discharge roller 26. In that case, the lower limit of L2 is a value obtained by adding a margin to the distance from the nip position of the discharge reversing roller 24 to the nip position of the inner discharge roller 26 to more reliably sandwich the end S1a in the inner discharge roller 26. can do.

Further, it is assumed that the transfer of the sheet S1 is temporarily stopped after the end portion S1a of the sheet S1 passes through the inner discharge roller 26 and then reaches the intermediate transfer roller 28 (FIG. 1). In this case, in order to superimpose the sheets S1 and S2, it is necessary to drive up to the intermediate transfer roller 28 by reversing the transfer direction in synchronization with the inner discharge roller 26. In order to keep the simple configuration in which the intermediate transfer roller 28 is driven only in one direction, an upper limit is set in L2. In that case, the upper limit of L2 is obtained by subtracting the margin for more reliably preventing the end S1a from coming into contact with the intermediate transfer roller 28 from the distance from the nip position of the discharge reversing roller 24 to the nip position of the intermediate transfer roller 28. Can be a value.

Further, the change of the standby position according to the length of the sheet in the transport direction described in the present embodiment may be performed only when the discharge destination of the sheet is the upper discharge tray 25. When the discharge destination of the sheet is the lower discharge tray 37, the sheet bundle S'is finally discharged from the superimposition processing unit 4B toward the sheet processing unit 71, and the sheet loaded on the upper discharge tray 25 is This is because it is difficult to interfere. Therefore, when the discharge destination is the lower discharge tray, the distance from the inversion to the stop after passing through the inner discharge roller 26 may be determined regardless of the length of the sheet in the transport direction.

(Modification example)
In the first and second embodiments, the inner discharge path 82 as the second transport path communicates with the sheet processing unit 71, but the second transport path communicates with the discharge destination other than the sheet processing section 71. The configuration may be used. For example, the sheet processing unit 71 may be omitted, and the sheet conveyed through the inner discharge path 82 may be discharged to the lower discharge tray 37 without being processed. Further, the second transport path may be a dead end configuration in which the second transport path does not communicate with the outside of the sheet processing device 4.

Further, in the first and second embodiments, the sheet discharging device of the sheet processing device 4 provided separately from the image forming device 1 has been described, but in the present technique, the sheet is removed from the image forming device 1 or another device that handles the sheet. It can also be applied to a sheet discharging device that discharges.

(Other embodiments)
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

1 ... Image forming device / 1S ... Image forming system / 4 ... Sheet processing device / 22 ... First transport means (roller before branching) / 24 ... Second transport means (discharge reversing roller) / 25 ... Loading section (upper discharge tray) ) / 26 ... Third transport means (inner discharge roller) / 27 ... Detection means (entrance sensor) / 71 ... Sheet processing unit / 81, 83 ... First transport path (acceptance path, first discharge path) / 82 ... 2 Transport path (inner discharge path) / 603 ... Control means (main control unit)

Claims (15)

The loading section where the seats are loaded and
A first transport means arranged on a first transport path extending toward the load section and transporting a sheet toward the load section.
A detection means that emits a detection signal according to the sheet passing through the first transport path, and
A second transport means arranged downstream of the first transport means on the first transport path, and the transport direction of the sheet received from the first transport means is reversed to reverse the transport direction of the first transport means and the second transport means. A second transport means for transporting to a second transport path branched from the first transport path with the transport means,
A third transport means arranged on the second transport path, the third transport means for reversing the transport direction of the sheet and transporting the sheet.
A control means for controlling the first transport means, the second transport means, and the third transport means.
Equipped with
The control means is
The first sheet received from the first transport means is inverted by the second transport means and delivered to the third transport means.
Based on the fact that the detection means emits the detection signal in response to the second sheet to be conveyed following the first sheet, the first sheet is directed to the third transfer means toward the second transfer means. And transport
With the ends of the first sheet and the second sheet aligned in the transport direction and the first sheet and the second sheet overlapped, the first sheet and the second sheet are pressed by the second transport means. Discharge to the loading section
A sheet ejection device characterized in that it is configured to perform an ejection operation. The control means attaches the first sheet to the third transport means at a timing when a predetermined time elapses after the detection means emits the detection signal according to the second sheet in the discharge operation. It is configured to be transported toward the transport means,
The predetermined time is set in advance in the second transport means so that the ends of the first sheet and the second sheet in the transport direction are aligned.
The sheet discharging device according to claim 1. The loading portion protrudes to the outside of the device main body of the sheet discharging device, and is
The sheet discharged above the loading section by the second transporting means falls to the loading section by gravity without being transported to a transporting means other than the second transporting means.
The sheet discharging device according to claim 1 or 2, wherein the sheet discharging device is characterized in that. In the discharging operation, the control means forms a sheet bundle with three or more sheets including the first sheet and the second sheet, and discharges the sheet bundle to the loading portion by the second transporting means. Is possible,
The sheet discharging device according to any one of claims 1 to 3. When the control means executes a job of discharging a plurality of sheets to the loading unit, the controlling means discharges the plurality of sheets to the loading unit in a state of being stacked for each preset number of sheets. Repeat the operation,
The sheet discharging device according to any one of claims 1 to 4. The control means performs the discharging operation according to the number of sheets discharged by the job so that each of the plurality of sheets is discharged to the loading unit in a state of being overlapped with any other sheet. Change the number of sheets to be stacked in the above job during the job,
The sheet discharging device according to claim 5. The control means is the third transport means from the second transport means when the transport of the first sheet by the third transport means is stopped after the first sheet is delivered to the third transport means. The stop position of the tip of the first sheet in the direction toward the sheet is changed according to the length of the first sheet in the sheet transport direction.
The sheet discharging device according to any one of claims 1 to 6, wherein the sheet discharging device is characterized. The control means has a second length in which the distance from the third transport means to the stop position when the first sheet is the first length is shorter than the first length of the first sheet. The stop position is changed so as to be longer than the distance from the third transport means to the stop position in the case of.
The sheet discharging device according to claim 7. In the control means, the length of the first sheet protruding toward the loading portion with respect to the second transport means is set in a state where the transport of the first sheet by the third transport means is stopped. , The stop position is set so as to be equal to or less than a predetermined value regardless of the length of the first sheet.
The sheet discharging device according to claim 7. With the loading unit as the first loading unit, it further has a second loading unit on which the sheets transported via the second transport path are loaded.
The control means executes control to change the stop position of the first sheet when the first sheet and the second sheet are discharged to the first loading unit, and the first sheet and the second sheet. Is not executed to change the stop position of the first sheet when the
The sheet discharging device according to any one of claims 7 to 9, wherein the sheet discharging device is characterized. The sheet discharging device according to any one of claims 1 to 10.
A sheet processing unit that processes a sheet transported via the second transport path, and a sheet processing unit.
A sheet processing device characterized by being provided with. Instead of the discharging operation, the control means obtains a plurality of sheets transported from the outside of the sheet processing device to the first transport path while the sheet is being processed in the sheet processing unit. It is possible to execute a buffer operation of superimposing by one transport means, the second transport means, and the third transport means, and then transporting the buffer to the sheet processing unit after the processing in the sheet processing unit.
The sheet processing apparatus according to claim 11. The control means controls the buffer operation so that the ends of the sheets stacked by the buffer operation in the transport direction are displaced from each other.
The sheet processing apparatus according to claim 12. The sheet processing unit is provided on the downstream side of the intermediate loading unit arranged in the device main body of the sheet processing device and the sheet discharging direction from the second transport path to the intermediate loading unit. The reference member, the moving member that moves the sheet discharged to the intermediate loading section toward the reference member to match, and the sheet treated in the sheet processing section are placed on the side opposite to the discharge direction. Equipped with an extruded member,
With the loading section as the first loading section, a second loading section provided below the first loading section and
Below the first transport path, a third transport path extending from the intermediate loading section toward the second transport section is further provided.
The sheet processed in the sheet processing section is loaded on the two loading sections.
The sheet processing apparatus according to claim 12. An image forming device that forms an image on a sheet,
The sheet processing apparatus according to any one of claims 11 to 14,
An image forming system characterized by comprising.

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