JP2013047133A - Post-processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a post-processing device on which a sheet to be added that is folded together with a saddle-stitched sheet bundle can be stacked without making contact with a staple of the saddle-stitched sheet bundle, and which can reduce the occurrence of jamming caused by the sheet to be added.SOLUTION: In a finisher 500, when a security sheet 701 is added on the saddle-stitched sheet bundle 710 to be folded together, a CPU 952 performs controls so that, after the saddle-stitched sheet bundle 710 has been moved to a retreat position, the security sheet 701 is additionally stacked on the saddle-stitched sheet bundle 710 while the saddle-stitched sheet bundle is moved from the retreat position to a folding position so that a tip of the security sheet 701 to be added does not make contact with the saddle-stitched part 840.

Description

  The present invention relates to a post-processing apparatus.

  2. Description of the Related Art Conventionally, post-processing apparatuses that perform various processes such as stapling and punching on sheets discharged from image forming apparatuses such as printers, copiers, and facsimiles are widely known. Japanese Patent Application Laid-Open No. 2004-133620 proposes a saddle stitch binding function in which sheets output from an image forming apparatus are stacked as a plurality of sheet bundles, a binding process is performed collectively, and the bound sheet bundle is folded and bound.

  In addition, regarding post-processing apparatuses in recent years, in addition to quality and productivity, security of deliverables has been required. Patent Document 2 proposes a post-processing device that wraps a product output from an image forming apparatus with a magnet sheet to improve the security of the product in order to improve the security of the product.

JP 2004-107083 A JP 2009-83962 A

  In a post-processing apparatus that performs saddle stitch bookbinding processing, in order to improve security, when a function for wrapping a product with a magnetic sheet as in Patent Document 2 is added, it is necessary to greatly change the processing configuration. Therefore, when one unbound sheet is stacked on the saddle-stitched sheet bundle and then folded, the bookbinding bundle is wrapped in the sheet, and the security of the product is maintained. In addition, the processing configuration of the post-processing apparatus does not have to be significantly changed.

  However, when a single sheet is stacked on a saddle-stitched sheet bundle, the leading edge of the sheet to be added may be caught by the staple of the saddle-stitched sheet bundle, causing jamming or damage to the sheet, resulting in lower quality. .

  The present invention reduces the jam that occurs due to the sheets to be added to be folded together with the saddle stitched sheet bundle without contacting the staples of the saddle stitched sheet bundle. It is an object of the present invention to provide a post-processing apparatus that can perform such processing.

  In order to achieve the above object, a post-processing apparatus of the present invention includes a tray for stacking conveyed sheets, a stacking unit for transporting and stacking sheets discharged from the image forming apparatus, and the tray. A saddle stitching means for saddle stitching a bundle of sheets of a predetermined number of sheets stacked on the tray; a center folding means for folding the sheet bundle saddle-stitched by the saddle stitching means; and the saddle stitched sheet bundle. In the post-processing apparatus provided with a moving unit that moves to a folding position where the middle folding unit performs the middle folding, when additional sheets are stacked on the saddle-stitched sheet bundle and then folded, the additional stacking is performed. The saddle-stitched sheet bundle is moved by the moving means so that the leading edge of the sheet to be contacted with the saddle stitching portion of the sheet bundle, and the sheets are additionally stacked by the stacking means. Characterized in that it comprises a Gosuru control means.

  According to the present invention, in a post-processing apparatus that collectively binds a plurality of sheets discharged from an image forming apparatus as a sheet bundle, a single unbound sheet is stacked on a saddle-stitched sheet bundle. In the case of half-folding, there are the following effects. The added sheet is stacked on the saddle-stitched sheet bundle without contacting the staples of the sheet bundle, and jamming caused by the added sheet can be reduced. Further, the bookbinding process can be performed without degrading the quality of the added sheet.

1 is a longitudinal sectional view showing a schematic structure of a main part of an image forming system including a post-processing apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of a controller that controls the entire image forming system in FIG. 1. It is a longitudinal cross-sectional view which shows schematic structure of the finisher 500 of FIG. FIG. 3 is a block diagram illustrating a schematic configuration of a finisher control unit 951 in FIG. 2. FIG. 2 is a diagram illustrating a display unit of an operation display device 600 in the image forming apparatus 10 of FIG. 1. (A) is a figure which shows an example of the application mode selection screen displayed on the display part of the operation display apparatus 600, (b) is a figure which shows an example of a paper feed stage selection screen. (A) is a figure which shows an example of the saddle stitch setting screen displayed on the display part of the operation display apparatus 600, (b) is a figure which shows an example of a security setting screen. 10 is a flowchart showing a flow of bookbinding processing by the finisher 500. 3 is a diagram illustrating an example of sheet information transmitted from the image forming apparatus 10. FIG. FIG. 6 is a diagram illustrating a state of a sheet bundle after being stapled at a staple position. FIG. 6 is a diagram illustrating a state of a sheet bundle 710 that moves to a retreat position. FIG. 10 is a diagram illustrating a state when a security sheet 701 is added to a sheet bundle 710 that moves from a retracted position to a folding position. 6 is a diagram illustrating a state of a sheet bundle 710 and a security sheet 701 that have been moved to a folding position. FIG. FIG. 10 is a diagram illustrating a state of a sheet bundle 710 that is projected by a protruding member 830. It is the figure which looked at the sheet bundle 710 wrapped with the security sheet 701 from the horizontal direction. FIG. 10 is a diagram for explaining a method of calculating a movement distance for moving the sheet bundle 710 to a retracted position.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a longitudinal sectional view showing a schematic structure of a main part of an image forming system including a post-processing apparatus according to an embodiment of the present invention.

  The image forming system in the present embodiment includes the image forming apparatus 10 and a finisher 500.

  First, the image forming apparatus 10 will be described, and details of the finisher 500 will be described later. Note that the image forming system is not limited to the illustrated configuration.

  The image forming apparatus 10 includes an image reader 200 that reads an image from a document, and a printer 350 that prints the read image on a sheet. In the image reader 200, the document feeder 100 and the operation display device 600 are arranged at the top. The operation display device 600 includes a plurality of keys for setting various functions relating to image formation, a display unit for displaying information indicating a setting state, and the like.

  The document feeder 100 feeds documents set upward on the document tray 101 one by one in order from the first page to the left in FIG. 1, and then flows on the platen glass 102 from the left through a curved path. Transport to the right after the reading position. The document that has passed the reading position is discharged toward the external paper discharge tray 112. The sink reading position is a predetermined image reading position set on the platen glass 102. A scanner unit 104 is fixed below the image reading position. When the original passes through the flow reading position from left to right, the original image is read by the scanner unit 104 held at a position corresponding to the flow reading position. When the original passes through the reading position, the original reading surface is irradiated with the light from the lamp 103 in the scanner unit 104, and the reflected light from the original is guided to the lens 108 via the mirrors 105, 106, and 107. . The light passing through the lens 108 forms an image on the light receiving surface of the image sensor 109. The image sensor 109 photoelectrically converts light on the light receiving surface and outputs image data. Image data output from the image sensor 109 is input to the exposure unit 110 in the printer 350 as a video signal.

  In this way, the original reading scan is performed by conveying the original so as to pass through the sink reading position from left to right. That is, when the original passes through the flow reading position, the entire original image is read by conveying the original in the sub-scanning direction while reading the original image by the image sensor 109 line by line in the main scanning direction. The main scanning direction here means a direction orthogonal to the document transport direction. Further, the sub-scanning direction means the document transport direction.

  It is also possible to read a document by conveying the document onto the platen glass 102 by the document feeder 100 and stopping it at a predetermined position, and moving the scanner unit 104 from left to right in this state. This reading method is a so-called fixed original reading method.

  When reading a document without using the document feeder 100, the user first lifts the document feeder 100 and places the document on the platen glass 102. Then, the original is read by moving the scanner unit 104 from the left to the right in FIG. When reading a document without using the document feeder 100, a fixed document reading is performed.

  The exposure unit 110 in the printer 350 modulates and outputs laser light based on the video signal input from the image reader 200. The laser light is irradiated onto the photosensitive drum 111 while being scanned by the polygon mirror 119. An electrostatic latent image corresponding to the irradiated laser beam is formed on the photosensitive drum 111. Here, the exposure unit 110 outputs laser light so that a correct image (an image that is not a mirror image) is formed on the photosensitive drum 111 during fixed document reading. The electrostatic latent image on the photosensitive drum 111 is visualized as a developer image by the developer supplied from the developing device 113.

  On the other hand, sheets fed by the pickup rollers 127 and 128 from the upper cassette 114 or the lower cassette 115 provided in the printer 350 are conveyed to the registration roller 126 by the feed rollers 129 and 130. When the leading edge of the sheet reaches the registration roller 126, the registration roller 126 is driven at an arbitrary timing, and the sheet is moved between the photosensitive drum 111 and the transfer unit 116 at a timing synchronized with the start of laser beam irradiation. Transport to. The developer image formed on the photosensitive drum 111 is transferred by the transfer unit 116 onto the fed sheet. The sheet on which the developer image is transferred is conveyed to the fixing unit 117. The fixing unit 117 fixes the developer image on the sheet by heating and pressing the sheet on which the developer image is transferred. The sheet that has passed through the fixing unit 117 is discharged from the printer 350 toward the finisher 500 through the flapper 121 and the discharge roller 118.

  Here, when the sheet is discharged with its image forming surface facing down (face down), the sheet that has passed through the fixing unit 117 is once guided into the reversing path 122 by the switching operation of the flapper 121. Thereafter, after the trailing edge of the sheet passes through the flapper 121, the sheet is switched back and discharged from the printer 350 by the discharge roller 118. This paper discharge form is called reverse paper discharge. This reverse paper discharge is performed when images are formed in order from the first page when forming an image read using the document feeder 100, and the sheet order after the paper discharge is the correct page order.

  Further, when a hard sheet such as an OHP sheet is fed from the manual sheet feeding unit 125 and an image is formed on this sheet, the image forming surface is faced up without leading the sheet to the reverse path 122 (face-up). ) By the discharge roller 118. Further, when double-sided recording for image formation is set on both sides of the sheet, the sheet is conveyed to the double-sided conveyance path 124 after being guided to the reverse path 122 by the switching operation of the flapper 121. Then, control is performed to feed the sheet guided to the duplex conveyance path 124 again between the photosensitive drum 111 and the transfer unit 116 at the timing described above.

  Next, a schematic configuration of a controller that controls the entire image forming system of FIG. 1 will be described with reference to FIG.

  FIG. 2 is a block diagram showing a configuration of a controller that controls the entire image forming system of FIG. The controller will be described as being disposed in the image forming apparatus 10 of FIG.

  As shown in FIG. 2, the controller includes a CPU circuit unit 900 including a CPU 901, a ROM 902, and a RAM 903. The CPU 901 is a CPU that performs basic control of the entire image type system of FIG. 1, and is connected to the ROM 902 and the RAM 903 by an address bus or a data bus. The CPU 901 comprehensively controls each control unit (911, 921, 922, 904, 931, 941, 951) by a control program stored in the ROM 902. The RAM 903 temporarily stores control data and is used as a work area for arithmetic processing associated with control.

  The document feeder control unit 911 controls driving of the document feeder 100 based on an instruction from the CPU circuit unit 900. The image reader control unit 921 performs drive control on the scanner unit 104 and the image sensor 109 described above, and transfers an analog image signal output from the image sensor 109 to the image signal control unit 922.

  The image signal control unit 922 performs various processes after converting the analog image signal from the image sensor 109 into a digital signal, converts the digital signal into a video signal, and outputs the video signal to the printer control unit 931. Further, the digital image signal input from the computer 909 via the external I / F 904 is subjected to various processes, and the digital image signal is converted into a video signal and output to the printer control unit 931. The processing operation by the image signal control unit 922 is controlled by the CPU circuit unit 900. The printer control unit 931 controls the exposure unit 110 based on the input video signal.

  The finisher control unit 951 is mounted on the finisher 500, and performs drive control of the entire finisher by exchanging information with the CPU circuit unit 900. This control content will be described later. The operation display device controller 941 exchanges information between the operation display device 600 and the CPU circuit unit 900. The operation display device 600 outputs a key signal corresponding to the operation of each key to the CPU circuit unit 900 and displays corresponding information based on the signal from the CPU circuit unit 900.

  Next, the configuration of the finisher 500 will be described with reference to FIG.

  FIG. 3 is a longitudinal sectional view showing a schematic structure of the finisher 500 of FIG.

  The finisher 500 performs post-processing such as a stapling process in which a plurality of sheets 700 discharged from the image forming apparatus 10 are bundled and stapled, a sorting process for sorting, and a bookbinding process for bookbinding. As shown in FIG. 3, the finisher 500 takes in the sheet 700 discharged from the image forming apparatus 10 into the inside by an inlet roller pair 511 and is conveyed through a conveying roller pair 520, a buffer roller pair 503, and a conveying roller pair 513. The

  A switching flapper 514 is disposed downstream of the discharge path 522. The switching flapper 514 is a flapper that switches between the processing tray 550 and the bookbinding path 523. A path sensor 573 is installed in the middle of the discharge path 522. The bookbinding intermediate processing tray 560 is provided with a sheet rear end pressing member 802 that is a sheet gripping member, a sheet position moving member 804, and a movable positioning member 805. In the case of the bookbinding process, the sheet 700 is guided to the bookbinding path 523 and conveyed to the bookbinding intermediate processing tray 560 via the conveyance roller pair 801. The sheets 700 conveyed to the bookbinding intermediate processing tray 560 are gripped and stacked one by one by the sheet trailing edge presser 802 to form a sheet bundle 710 of a predetermined number of sheets 700.

  An anvil 820b is provided at a position facing the stapler 820a, and the stapler 820a and the anvil 820b cooperate to bind the sheet bundle 710. On the downstream side of the stapler 820a, a protruding member 830 is provided at a position opposite to the folding roller pair 810a, 810b and the folding roller pair 810a, 810b.

  By projecting the protruding member 830 against the sheet bundle 710 stacked on the bookbinding intermediate processing tray 560, the sheet bundle 710 stored in a bundle on the bookbinding intermediate processing tray 560 is pushed out between the folding roller pairs 810a and 810b. The folded sheet bundle 710 is transferred to the folding and bookbinding conveyance roller pair 811a and 811b via the folding roller pair 810a and 810b, and is discharged to the bookbinding tray 850.

  The paper discharge roller pair 512 discharges the sheet to the paper discharge tray 800. The bundle discharge roller pair 551 discharges the sheet bundle to the discharge tray 880. The entrance sensor 570 is a sensor for detecting the passage of the sheet 700. The bookbinding entrance sensor 571 is a sensor for detecting that the sheet 700 has passed the bookbinding path 523. The saddle vertical path sensor 572 is a sensor for detecting that the sheet 700 is stacked on the bookbinding intermediate processing tray 560.

  Next, a schematic configuration of the finisher control unit 951 that drives and controls the finisher 500 will be described with reference to FIG.

  FIG. 4 is a block diagram showing a schematic configuration of the finisher control unit 951 in FIG.

  As shown in FIG. 4, the finisher control unit 951 includes a CPU 952, a ROM 953, a RAM 954, and the like. The finisher control unit 951 performs data communication with the CPU circuit unit 900 in the image forming apparatus 10 via a communication IC (not shown), and executes various programs stored in the ROM 953 based on instructions from the CPU circuit unit 900. The drive control of the finisher 500 is performed.

  The CPU 952 controls the inlet motor M1 that drives the inlet roller pair 511 and the transport roller pair 520, the buffer motor M2 that drives the buffer roller pair 503, the paper discharge roller pair 512, and the paper discharge motor M3 that drives the transport roller pair 513. . The CPU 952 is a means for driving various members of the processing tray 550. The bundle discharge motor M6 that drives the bundle discharge roller pair 551, the swing guide motor M4 that drives the swing guide (not shown) up and down, and not shown. The alignment motor M5 that drives the alignment member is controlled. Further, the CPU 952 receives input signals from the entrance sensor 570, the path sensor 573, and the like.

  Further, the CPU 952 includes a conveyance motor M7 that drives the conveyance roller pair 801, a folding motor M8 that drives the folding roller pair 810a and 810b, a thrust motor M9 that drives the ejection member 830, and a bundle movement motor M10 that drives the positioning member 805. Control. Further, it controls a stapler motor M11 for driving the stapler 820, a bookbinding transport motor M12 for driving the bookbinding transport roller pair 811a, 811b, a rear end presser motor M13 for driving the sheet rear end presser 802, and the like. Further, the CPU 952 receives detection signals from the bookbinding entrance sensor 571 and the saddle longitudinal path sensor 572.

  FIG. 5 is a diagram showing a display unit of the operation display device 600 in the image forming apparatus 10 of FIG.

  The operation display device 600 includes a start key 602 for starting an image forming operation, a stop key 603 for interrupting the image forming operation, ten keys 604 to 612, 614, an ID key 613, a clear key 615, a reset key 616, and the like. Is arranged. In addition, a display unit 620 having a touch panel formed thereon is arranged, and a soft key can be created on the screen. For example, the image forming apparatus 10 has various processing modes such as non-sorting, sorting, and bookbinding mode as finish processing modes of the finisher 500. Setting such a processing mode is performed by an input operation from the operation display device 600.

  Next, the flow of bookbinding mode setting will be described with reference to FIGS.

  In the bookbinding mode, the user performs settings on the display unit 620 shown in FIG. When the user selects the “applied mode” key 617, which is a soft key, while the initial screen shown in FIG. 5 is displayed on the display unit 620, the CPU 901 transitions to the applied mode selection screen 61 shown in FIG. To do.

  Next, the user sets the application mode. When the user selects the “bookbinding” key 618 on the application mode selection screen 61, the CPU 901 transitions to the paper feed stage selection screen 62 shown in FIG. On the other hand, when the user selects the “Close” key 619 on the application mode selection screen 61, the CPU 901 makes a transition to the initial screen shown in FIG. 5.

  Next, the user selects a paper feed stage to be bound. When the user selects the “Next” key 622 after selecting the paper feed stage on the paper feed stage selection screen 62, the CPU 901 transits to the saddle stitch setting screen 71 shown in FIG. On the other hand, when the user selects the “return” key 621 on the paper feed stage selection screen 62, the CPU 901 transits to the application mode selection screen 61.

  Next, the user selects whether or not saddle stitching is set. When performing saddle stitching, the user selects the “saddle stitching” key 623 on the saddle stitching setting screen 71. On the other hand, in the case of unbound binding, the user selects the “Do not saddle stitch” key 624. When the user selects the “next” key 626 after selecting the “saddle stitching” key 623 on the saddle stitching setting screen 71, the CPU 901 transits to the security setting screen 72 shown in FIG. On the other hand, when the user selects the “do not saddle stitch” key 624 on the saddle stitch setting screen 71 and then selects the “next” key 626, the CPU 901 transits to the initial screen shown in FIG. 5. When the user selects the “return” key 625 on the saddle stitching setting screen 71, the CPU 901 transits to the paper feed stage selection screen 62.

  Next, the user selects presence / absence of security settings. When the saddle stitch booklet bundle is wrapped with unbound paper, the user selects the “with security” key 627. In the case of a normal saddle stitch bookbinding bundle, the user selects the “no security” key 628. When the user presses the “next” key 630 after selecting the “with security” key 627 or “without security” key 628 on the security setting screen 72, the CPU 901 transits to the initial screen shown in FIG. When the user selects the “return” key 629 on the security setting screen 72, the CPU 901 transits to the saddle stitch setting screen 71. When the user presses the start key 602, the bookbinding process is started.

  Next, the flow of bookbinding processing by the finisher 500 will be described with reference to FIGS.

  In the present embodiment, an operation process when the number of jobs is N and the “security present” key 627 is selected on the security setting screen 72 displayed on the operation display device 600 will be described.

  FIG. 8 is a flowchart showing a bookbinding process executed by the CPU 952 of the finisher 500.

  When the user sets the bookbinding processing and presses the start key 602 (FIG. 5), the CPU 952 receives the sheet information 750 from the image forming apparatus 10 (step S2001). The sheet information 750 includes information indicating the size of each sheet, processing performed on the sheet, and the like. Before the sheet 700 is transported to the finisher 500, the CPU 901 in the image forming apparatus 10 stores the information in the finisher 500. It is transmitted to the CPU 952. One sheet information 750 is transmitted for one sheet 700. The CPU 952 receives one sheet information 750 each time one sheet 700 is conveyed.

  Here, the sheet information 750 set by the CPU 901 will be described with reference to FIG. In the illustrated example, the case where the number of jobs N is 7 and the user selects the “with security” key 627 on the security setting screen 72 displayed on the operation display device 600 is used as an example.

  When the user presses the start key 602 to start the bookbinding process, the CPU 901 sets ON (1) for the leading sheet flag of the first sheet information 750. In the seventh sheet information 750, which is the number of saddle stitched sheets, ON (1) is set in the staple command in order to perform saddle stitching. After that, an unbound sheet (hereinafter referred to as “security sheet 701”) is stacked on the saddle-stitched sheet bundle 710 to perform half-folding. Therefore, the CPU 901 issues a security command for the eighth sheet information 750. Set ON (1). Further, since the eighth sheet is the last sheet, the CPU 901 sets ON (1) for the last sheet flag.

  In step S2002 of FIG. 8, the CPU 952 analyzes the received sheet information 750 and determines whether or not the security command is ON (1). When determining that the security command is OFF (0) (NO in step S2002), the CPU 952 drives the inlet motor M1, the buffer motor M2, the paper discharge motor M3, and the transport motor M7 (step S2003). As a result, the inlet roller pair 511, the transport roller pair 520, the buffer roller pair 503, the transport roller pair 513, and the transport roller pair 801 are rotated, and the sheet 700 is transported to the bookbinding intermediate processing tray 560 (step S2003).

  In order to prevent a collision between the conveyed sheet 700 and the rear end of the sheet bundle 710 being stacked on the bookbinding intermediate processing tray 560, the CPU 952 drives the rear end holding motor M13 so that the sheet bundle 710 is driven by the sheet rear end holding 802. The rear end is gripped (step S2004). Then, the sheets 700 are stacked on the bookbinding intermediate processing tray 560 (step S2004). Release the grip after loading. If the sheet 700 being conveyed is the first sheet of a bundle, it is not necessary to perform a gripping operation by the sheet rear end press 802.

  Next, when the CPU 952 determines that the stapling command of the sheet information 750 of the sheet 700 is OFF (0) (NO in step S2005) and the final paper flag is OFF (0) (NO in step S2006), the CPU 952 starts again from step S2001. The process of step S2006 is performed. Until the final sheet is conveyed, the processing from step S2001 to step S2006 is repeated for each sheet discharged from the image forming apparatus 10. Thereby, it is possible to specify the timing of the sheet to be saddle stitched and the security sheet.

  Since the CPU 901 sets the staple command for the N-th sheet information 750 to ON (1), the following processing is performed for the N-th sheet information 750.

  If the CPU 952 determines that the stapling instruction of the sheet information 750 of the sheet 700 is ON (1) (YES in step S2005), the CPU 952 drives the stapler motor M11 to bind the sheet bundle 710 stacked on the bookbinding intermediate processing tray 560. (Step S2007). Since the CPU 901 sets the last sheet flag of the Nth sheet information 750 to OFF (0), the processing from step S2001 to step S2006 is performed again.

  Since the CPU 901 sets the security command for the (N + 1) th sheet information 750 to ON (1), the following processing is performed for the (N + 1) th sheet information 750.

  If the CPU 952 determines that the security command of the sheet information 750 of the sheet 700 is ON (1) (YES in step S2002), the process proceeds to step S2008.

  In step S2008, the CPU 952 drives the bundle movement motor M10 to move the sheet bundle 710 at the position shown in FIG. 10 to the retracted position provided on the upstream side in the sheet bundle conveyance direction as shown in FIG. Move. This is to prevent the leading end of the security sheet 701 being conveyed from coming into contact with the staple in the saddle stitch portion 840 of the sheet bundle 710. At this time, the sheet bundle 710 moves so that the leading end of the security sheet 701 is in contact with the leading end side of the sheet bundle 710 (downstream in the sheet bundle conveying direction) rather than the saddle stitching portion 840 of the sheet bundle 710. The retreat position is set at a position away from the stapling position of the sheet bundle 710 shown in FIG. 10 by a predetermined distance upstream in the sheet bundle conveyance direction. A method of calculating the movement distance for moving the sheet bundle 710 to the retreat position that is a predetermined distance away from the staple position will be described later.

  The CPU 952 drives the inlet motor M1, the buffer motor M2, the paper discharge motor M3, and the conveying motor M7 to rotate the inlet roller pair 511, the conveying roller pair 520, the buffer roller pair 503, the conveying roller pair 513, and the conveying roller pair 801. .

  If the CPU 952 determines that the leading end of the added security sheet 701 has reached the positioning member 805 (FIG. 12) based on the detection signal from the saddle vertical path sensor 572, the CPU 952 drives the bundle movement motor M10. As a result, the sheet bundle 710 placed on the positioning member 805 moves from the retracted position to the folding position. The fact that the leading end of the security sheet 701 has reached the positioning member 805 is determined when a predetermined time elapses after the saddle vertical path sensor 572 detects the sheet. This predetermined time is the time required for the leading end of the security sheet 701 to be conveyed from the saddle vertical path sensor 572 to the positioning member 805 in a state where the positioning member 805 is at the position shown in FIG.

  In step S2009, when adding the security sheet 701, the CPU 952 may control the movement so that the leading end of the security sheet 701 contacts the leading end side of the sheet bundle 710 rather than the saddle stitching portion 840 of the sheet bundle 710. In addition, when adding the security sheet 701, the CPU 952 causes the saddle stitching portion 840 of the sheet bundle 710 to be closer to the retracted position of the sheet bundle 710 than the discharge port front end 803 from which the security sheet 701 is discharged. It is good to control movement.

  Next, the CPU 952 drives the bundle movement motor M10 to move the sheet bundle 710 to the folding position as shown in FIG. 13 (step S2010).

  As shown in FIG. 14, the CPU 952 drives the folding motor M8 to rotate the pair of folding rollers 810a and 810b and simultaneously drives the thrust motor M9 to fold the projecting member 830 into the sheet bundle 710 (step). S2012).

  Next, the CPU 952 drives the folding motor M8 to rotate the pair of folding rollers 810a and 810b, and folds and conveys the sheet bundle 710 (step S2013). Then, the bookbinding transport motor M12 is driven to discharge the sheet bundle 710 to the bookbinding tray 850 by the bookbinding transport roller pair 811a and 811b (step S2014). As shown in FIG. 15, the sheet bundle 710 is discharged in a state of being wrapped with a security sheet 701.

  Next, a method for calculating the movement distance for moving the sheet bundle 710 to the retracted position will be described with reference to FIG.

  FIG. 16 is a diagram for explaining a method of calculating a movement distance for moving the sheet bundle 710 to the retracted position.

  Assume that the intersection of the perpendicular line from the paper discharge outlet tip 803 from which the security sheet 701 is discharged to the bookbinding intermediate processing tray 560 and the bookbinding intermediate processing tray 560 is the paper discharge outlet front position 590. The staple position 720 is a position where the stapler 820a and the anvil 820b cooperate to bind the staples to the sheet bundle 710. The distance between the paper discharge outlet front end position 590 and the staple position 720 is X. The movement distance Z for moving the sheet bundle 710 to the retracted position can be calculated by the following equation.

Movement distance (Z) = distance (X) from the discharge port front end position 590 to the staple position 720 + predetermined amount (for example, 10 mm)
As shown in FIG. 16, the sheet bundle 710 after saddle stitching is moved by the movement distance Z. A solid line A in FIG. 16 is the position of the positioning member 805 after the sheet bundle 710 is moved. A broken line B is the position of the positioning member 805 before moving the sheet bundle 710.

  According to the above-described embodiment, when the security sheet 701 is added on the saddle-stitched sheet bundle 710 and then folded, the following operation is executed. That is, the saddle-stitched sheet bundle 710 is moved to the retracted position so that the leading end of the security sheet 701 to be added does not contact the saddle-stitched portion 840 of the sheet bundle 710, and then moved from the retracted position to the folding position. Then, one additional security sheet 701 is stacked. As a result, the sheets to be added for improving security are stacked without contacting the staples of the saddle stitched sheet bundle, and jamming caused by the added sheets can be reduced.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

10 Image forming apparatus 500 Finisher 560 Bookbinding intermediate processing tray 750 Sheet information 802 Sheet rear end press 805 Positioning members 810a and 810b Folding roller pairs 820a and 820b Staplers 901 and 952 CPU

Claims (7)

A tray for stacking conveyed sheets;
A stacking unit that transports a sheet discharged from the image forming apparatus and stacks the sheet on the tray;
Saddle stitching means for saddle stitching a bundle of sheets of a predetermined number of sheets stacked on the tray;
A center folding means for folding the sheet bundle that has been saddle stitched by the saddle stitching means;
A post-processing apparatus comprising: a moving unit that moves the saddle-stitched sheet bundle to a folding position where the middle folding unit performs the middle folding;
When a sheet is additionally stacked on the saddle-stitched sheet bundle and then folded in half, the saddle-stitched sheet is arranged so that the leading edge of the additionally stacked sheet does not contact the saddle stitch portion of the sheet bundle. A post-processing apparatus comprising: control means for controlling the stack to be moved by the moving means and the sheets to be additionally stacked by the stacking means.   The control unit moves the saddle-stitched sheet bundle to a retracted position provided on the upstream side in the transport direction of the sheet bundle by the moving unit, and then downstream from the retracted position in the transport direction of the sheet bundle. 2. The post-processing apparatus according to claim 1, wherein the sheet is additionally stacked by the stacking unit while being moved to the folding position.   When the sheet is additionally stacked by the stacking unit on the saddle-stitched sheet bundle, the control unit is configured such that the leading end of the sheet is in the direction in which the sheet bundle is folded relative to the saddle-stitched portion of the sheet bundle. The post-processing apparatus according to claim 2, wherein the movement of the sheet bundle by the moving means is controlled so as to contact the sheet bundle on the side.   When the sheet is additionally stacked by the stacking unit on the saddle-stitched sheet bundle, the control unit includes a sheet discharge port for a sheet to be additionally stacked by the stacking unit. 4. The post-processing apparatus according to claim 2, wherein the movement of the sheet bundle by the moving unit is controlled so as to be closer to the retracted position of the sheet bundle than the leading edge of the sheet.   The intersection of the tray and a perpendicular line from the leading end of the sheet discharge port to the tray and the tray is defined as the discharge port leading end position, and the stapling position is defined as a position where a staple is bound to the sheet bundle by the saddle stitching unit. The distance obtained by adding a predetermined amount to the distance between the front end position of the paper mouth and the stapling position is set as the movement distance of the saddle stitched sheet bundle to the retracted position. The post-processing apparatus as described in a term.   The post-processing according to any one of claims 1 to 5, wherein the half-folding unit performs the middle folding so that the saddle-stitched sheet bundle is wrapped with the additional stacked sheets. apparatus.   The control means identifies a sheet to be additionally stacked on the saddle stitched sheet bundle from sheet information transmitted from the image forming apparatus for each sheet discharged from the image forming apparatus. The post-processing apparatus according to any one of 1 to 6.

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