Image formation system having sheet processing device

Abstract

To effectively prevent misalignment of a punching position in a two-folded sheet bundle (saddle-stitched booklet) when performing square-folding processing on the two-folded sheet bundle.SOLUTION: An image formation system comprises: punching means for performing punching processing at predetermined locations on a sheet on which an image is formed; sheet loading means for sequentially loading the sheet on which the image is formed or the sheet to which punching processing is performed to form a sheet bundle; folding means for performing center-folding processing on the sheet bundle to produce a two-folded sheet bundle; pressing means for applying pressure to a back part of the two-folded sheet bundle produced by the folding means to process the back part of the sheet bundle into the planar shape; and control means for controlling the punching means and the pressing means. The control means sets a distance from the fold of the sheet bundle to the punching position during the punching processing by the punching means for the sheet bundle to which the pressing processing is performed, longer than a distance from the fold to the punching position during the punching processing for the sheet bundle to which the pressing processing is not performed.SELECTED DRAWING: Figure 18

Description

Technical Field

[0001] The present invention relates to an image forming system including a sheet processing apparatus that sequentially receives an image-formed sheet to form a sheet bundle, performs a punching process after folding the sheet bundle in half, and creates a booklet.

Background Art

[0002] Conventionally, there has been known an apparatus that performs sheet processing (sheet post-processing) which receives an image-formed (printed) sheet to form a sheet bundle of a predetermined number of sheets, and performs post-processing such as binding processing or punching processing on this sheet bundle.

[0003] In addition, there are also known sheet processing apparatuses that form an image on a large-sized sheet, cut the sheet at an intermediate position in the longitudinal direction along the sheet width direction to form two sheets, fold the sheet bundle in half (center fold), perform a punching process along the center fold line, perform a center binding process to make a book (create a booklet), and a sheet processing apparatus called a chestnut processing that attaches a cover to the booklet thus created.

[0004] These sheet processing apparatuses are usually arranged with an image forming apparatus (printing machine) on their upstream side and a sheet (sheet bundle) stacking apparatus for stacking the post-processed sheet bundle on their downstream side, and constitute an image forming system that performs inline sheet post-processing (inline processing) for mutually transmitting and receiving sheet information and sheet processing information among these image forming apparatuses, sheet processing apparatuses, and sheet stacking apparatuses.

[0005] In addition, among sheet processing apparatuses, there is a type that first performs a stapling process or a punching process at an intermediate position in the longitudinal direction of a sheet bundle, then folds the sheet bundle along its intermediate position in the longitudinal direction, and finally applies pressure to the intermediate position (crease) in the longitudinal direction of the folded sheet bundle to perform sheet bundle processing (bookbinding processing).

[0006] However, for example, when the longitudinal intermediate position of a stapled sheet bundle is bent along the direction of the staples, the sheet bundle will curve along the fold due to the elasticity of the sheets (the strength of the sheet's waist), making it difficult to open the back of the sheet bundle flat (into a flat bound state).

[0007] For this reason, conventionally, a device has been proposed that applies pressure in a direction perpendicular to the back of a sewn-bound sheet bundle to make the shape of the fold on the back into a planar shape (see, for example, "Patent Document 1"). A device for performing a square fold process of applying pressure in a direction perpendicular to the back of a sheet bundle to forcibly form a corner (fold) on the back of the sheet bundle is known (see, for example, Patent Document 1).

[0008] In this way, by performing a square fold process on the folded sheet bundle, not only does the appearance of the sewn-bound booklet improve, but the stackability of the sheet bundle can also be enhanced.

[0009] However, in such a square fold process, since the number of sheets, sheet size, and the strength of the sheet's waist due to the thickness and strength of the sheets that make up the sheet bundle vary widely, the optimal value of the pressure to be applied to the back of the sheet bundle in the square fold process is not uniform.

[0010] For example, when performing sewn binding and square fold processing on a sheet bundle formed of thin sheets, since the thin sheets have a weaker waist compared to normal sheets, the pressure required during the folding process is relatively small. On the other hand, when performing sewn binding and square fold processing using thick sheets, since the thick sheets have a stronger waist compared to normal sheets, a relatively strong pressure is required to overcome the strength of the waist during the folding process.

[0011] Therefore, in the square folding process of the sheet bundle, if the pressing process is not performed according to the characteristics of the sheets constituting the sheet bundle, the form of the sheet bundle to be bound may be impaired. For example, when performing the square folding process by applying excessive pressure to a sheet bundle of thin sheets, there is a risk that the shape of the back of the sheet bundle will be crushed and damaged. On the other hand, when performing the square folding process on a sheet bundle to be bound of thick sheets with weak and insufficient pressure, the shape of the back of the sheet bundle will not become flat but will bulge, and an appropriate square force process cannot be performed.

[0012] For this reason, when executing the square folding process, a device has been proposed that sets the pressure applied to the back of the sheet bundle and performs the square folding process based on the set pressure (see, for example, Patent Document 2).

[0013] Regarding a saddle-stitching device that folds a sheet bundle in half (center fold) and performs a punching process along the center fold line, when performing a complicated punching operation for filing sheets or a saddle-stitching binding operation, an image forming system is disclosed that performs a punching process and / or a stapling process on an arbitrary number of copies with respect to the set number of copies (see, for example, Patent Document 3).

[0014] In the device disclosed in this Patent Document 3, it is configured to receive the sheets discharged from the image forming device, convey them one by one, perform a plurality of punching processes at positions substantially symmetric with respect to the intermediate position in the longitudinal direction of the sheets, and then perform a saddle-stitching binding process. For example, it is configured to create a bound booklet as shown in FIGS. 22 to 24 of the present application.

[0015] However, in such a device, when perforating the sheet bundle, the deviation of the hole position is not taken into account. Therefore, when forming a sheet bundle by folding in half a plurality of sheets that have been perforated in a state where they are overlapped with each other, for example, as shown in FIGS. 7(a) and 7(b), the position of the perforation gradually deviates by the thickness of the sheet, and there is a problem that the diameter of the perforation applied to the sheets constituting the sheet bundle becomes substantially smaller.

[0016] In order to solve this problem, there is also known a device that corrects the position where the perforation process is performed on the sheet to change the deviation of the perforation of the folded sheet bundle (see, for example, Patent Document 4).

Prior Art Documents

Patent Documents

[0017]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0018] However, if a square fold process is performed on the folded and perforated sheet bundle to process the shape of the fold line on the back into a flat state, the amount of crushing of the back of the sheet bundle due to the square fold process is not taken into account. Therefore, as shown in FIG. 23 of the present application, there is a problem that the perforation position of the double-folded sheet bundle (a booklet subjected to the center-stitching binding process) deviates by the amount of crushing of the back of the sheet bundle due to the square fold process from the expected position.

[0019] Therefore, an object of the present invention is to perform a square fold process on a double-folded sheet bundle, and by the square fold process, prevent displacement of the perforation position of the double-folded sheet bundle (a booklet subjected to center binding).

Means for Solving the Problem

[0020] To achieve the above object, the present invention provides an image forming system including a forming device for performing image formation on a sheet, a sheet post-processing device and a sheet stacking device for performing post-processing on the image-formed sheet, a perforating means for performing a perforation process on a predetermined position of the image-formed sheet, a sheet stacking means for sequentially stacking the image-formed sheet or the perforated sheet to generate a sheet bundle, a folding means for performing a middle folding process on the sheet bundle to form a fold line and generate a double-folded sheet bundle, a pressing means for pressing the back of the double-folded sheet bundle generated by the folding means to make the back of the sheet bundle flat, and a control means for controlling the perforating means and the pressing means. As a first control example of the control means, the distance from the fold line of the sheet bundle to the perforation position in the perforation process of the sheet bundle by the perforating means for the sheet bundle on which the pressing process is performed is made longer than the distance from the fold line to the perforation position in the perforation process for the sheet bundle on which the pressing means is not applied.

[0021] Also, as a second control example of the present invention, the control means recognizes the number of sheets constituting the sheet bundle formed by the stacking means, determines whether the number of sheets forming the sheet bundle exceeds a preset reference number or is less than the reference number, and makes the distance from the fold line of the sheet bundle to the perforation position in the perforation process of the sheet bundle by the perforating means for the sheet bundle exceeding the reference number longer than the distance from the fold line to the perforation position in the perforation process for the sheet bundle less than the reference number.

[0022] Furthermore, as a third control example of the present invention, the control means recognizes the number of sheets constituting the sheet bundle formed by the stacking means, determines whether the number of sheets forming the sheet bundle exceeds a preset reference number or is less than the reference number, and determines the distance from the fold of the sheet bundle in the perforation process by the perforation means for the sheet bundle exceeding the reference number to be longer than the distance from the fold to the perforation position in the perforation process for the sheet bundle less than the reference number.

[0023] And, as a fourth control example of the present invention, the control means recognizes the basis weight of the sheet bundle formed by the stacking means, determines whether the basis weight of the sheet bundle exceeds a preset reference value or is less than the reference value, and determines the distance from the fold of the sheet bundle in the perforation process by the perforation means for the sheet bundle exceeding the reference value to be longer than the distance from the fold to the perforation position in the perforation process for the sheet bundle less than the reference value.

Advantages of the Invention

[0024] According to the present invention, when performing a square fold process on a double-folded sheet bundle, when performing a plurality of perforation processes at positions substantially symmetric with respect to the fold located in the middle of the longitudinal direction of the sheet, by performing correction corresponding to various situations of the sheet bundle by the amount of crushing of the back of the sheet bundle due to the square fold process, it is possible to effectively prevent the perforation positions of the double-folded sheet bundle (a booklet subjected to saddle-stitching binding) from shifting.

Brief Description of the Drawings

[0025]

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Embodiments for Carrying Out the Invention

[0026] Hereinafter, with reference to the drawings, exemplary preferred embodiments of the present invention will be described in detail. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in the following embodiments should be appropriately changed according to the configuration of the apparatus to which the present invention is applied and various conditions. Therefore, unless specifically stated otherwise, the scope of the present invention is not intended to be limited only to those.

[0027] <Image forming apparatus> FIG. 1 is a configuration diagram of an image forming apparatus and a sheet processing apparatus. As shown in FIG. 1, the image forming apparatus includes an image forming apparatus main body 600 that performs black-and-white / color image formation, a perforating apparatus 200 as a sheet processing apparatus connected thereto, and a sheet processing apparatus (hereinafter referred to as a finisher 100). Therefore, the sheets discharged from the image forming apparatus main body 600 can be processed by the on-line connected perforating apparatus 200 and finisher 100. Note that the image forming apparatus main body 600 can be used alone without connecting the finisher 100 to the discharge port. Further, the image forming apparatus main body 600 may integrally incorporate the perforating apparatus 200 and the finisher 100 as a sheet discharging apparatus. Here, the position facing the operation unit 601 for the user to perform various inputs / settings on the image forming apparatus main body 600 is referred to as the front near side (hereinafter referred to as the front side) of the image forming apparatus, and the back side of the apparatus is referred to as the back side. FIG. 1 shows the configuration of the image forming apparatus as viewed from the front side of the apparatus. The perforating apparatus 200 and the finisher 100 are connected to the side portion of the image forming apparatus main body 600.

[0028] Sheets S supplied from cassettes 909a and 909b within the image forming apparatus main body 600 are each transferred with four-color toner images by yellow, magenta, cyan, and black photosensitive drums 914a to 914d and the like that constitute the image forming unit. Then, they are conveyed to the fixing unit 904 to fix the toner images. In the case of the single-sided image forming mode, they are directly discharged outside the apparatus main body from the discharge roller pair 907. In the case of the double-sided image forming mode, the sheet S is transferred from the fixing unit 904 to the reversing roller 905. When the rear end in the sheet conveyance direction exceeds the reverse switching section P, the reversing roller 905 is reversely rotated, and the sheet is conveyed in the direction of the double-sided conveyance rollers 906a to 906f opposite to the conveyance direction. Then, again, four-color toner images are transferred to the back surface by the yellow, magenta, cyan, and black photosensitive drums 914a to 914d and the like. The sheet S transferred on both sides is conveyed to the fixing unit 904 again to fix the toner image, and is discharged outside the apparatus main body from the discharge roller pair 907.

[0029] FIG. 2 is a block diagram of an image forming apparatus control unit that controls an image forming apparatus. As shown in FIG. 2, the CPU circuit unit 630 includes a CPU 629, a ROM 631, and a RAM 655. The CPU circuit unit 630 controls a document feeder control unit 632, an image reader control unit 633, an image signal control unit 634, a printer control unit 635, a finisher control unit 636, a punching device control unit 638, and an external interface 637. The CPU circuit unit 630 controls according to the programs stored in the ROM 631 and the settings of the operation unit 601. The document feeder control unit 632 controls the document feeder 650. The image reader control unit 633 controls the image reader. The printer control unit 635 controls the image forming apparatus main body 600. The punching device control unit 638 controls the punching device 200. The finisher control unit 636 controls the finisher 100. In the present embodiment, the configuration in which the punching device control unit 638 and the finisher control unit 636 are mounted on the finisher 100 will be described. However, the present invention is not limited to this, and may be provided in the image forming apparatus main body 600 integrally with the CPU circuit unit 630 to control the punching device 200 and the finisher 100 from the side of the image forming apparatus main body 600. Alternatively, the finisher 100 may be controlled by the control means on the punching device 200 side, or the punching device 200 may be controlled by the control means on the finisher 100 side.

[0030] The RAM 655 is used as a region for temporarily holding control data and a work region for operations associated with control. The external interface 637 is an interface from a computer (PC) 620, and develops print data into an image and outputs it to the image signal control unit 634. An image read by the image sensor is output from the image reader control unit 633 to the image signal control unit 634, and the image output from the image signal control unit 634 to the printer control unit 635 is input to the exposure control unit.

[0031] The punching device control unit 638 is mounted on the punching device 200, and performs drive control of the entire punching device by exchanging information with the CPU circuit unit 630 of the image forming apparatus. The finisher control unit 636 is mounted on the finisher 100, and performs drive control of the entire finisher by exchanging information with the CPU circuit unit 630 of the image forming apparatus. The punching device control unit 638 and the finisher control unit 636 control various motors and sensors.

[0032] Also, at the operation unit 601, the user can perform various inputs / settings such as print job information. For example, on the operation unit 601, a setting for saddle stitching binding as shown in FIG. 20 is displayed, and the user can select whether to individually perform saddle stitching processing, punching processing, and square fold processing. Details of the saddle stitching processing, punching processing, and square fold processing will be described later.

[0033] <Punching Device> FIG. 3 is a cross-sectional view of the punching device 200. As shown in FIG. 3, the punching device 200 includes a punching path B that sequentially takes in the sheets discharged from the image forming apparatus main body 600 and performs punching processing on the taken-in sheets, and a bypass A that passes the sheets to the downstream finisher 100 without processing. These paths are switched by a switching member 217.

[0034] The sheet processing in the punching device 200 operates according to the user's settings by the operation unit 601 provided in the image forming apparatus main body 600.

[0035] The sheets discharged from the image forming apparatus main body 600 are delivered to the inlet roller pair 202 of the punching device 200. At this time, the delivery timing of the sheets is also detected simultaneously by the inlet sensor 201.

[0036] When the sheets are not subjected to punching processing, they are switched to the bypass A by the switching member 217, conveyed by the conveying roller pairs 203, 204, 205, and the discharge roller pair 206, and delivered to the downstream finisher 100.

[0037] When perforating the sheet, the switching member 217 switches to the perforation path B, and the sheet is conveyed to the processing unit by the conveying roller pairs 208, 211, and 252, and the sheet edge detection sensor 213 detects the sheet edge. Then, after stopping the sheet at a predetermined position in the conveying direction, the perforating unit 220 is operated to perforate the sheet. The perforated sheet is conveyed again and conveyed by the conveying roller pairs 209, 210, 214, 215, 216 and the discharge roller pair 206, and is delivered to the downstream finisher 100.

[0038] FIG. 5 is a cross-sectional view of the perforating unit 220 as viewed from the downstream in the sheet conveying direction. The die plate 305 has a perforation groove 306. Shaft guides 307a and 307b are erected on the die plate 305 and slidably support the movable plate 301 and the perforation forming blade holder 303. The perforation forming blade 304 is installed on the perforation forming blade holder 303 and engages with the perforation groove 306 to perforate the sheet. Pressing springs 302a, 302b, and 302c are installed between the movable plate 301 and the perforation forming blade holder 303. By pushing down the movable plate 301 with the drive motor M1, the pressing springs 302a, 302b, and 302c push down the perforation forming blade holder 303, and the perforation forming blade 304 engages with the perforation groove 306. The release springs 308a and 308b are springs that push up the pushed-down perforation forming blade holder 303. The top dead center of the perforation forming blade holder 303 is the position where it abuts against the stoppers 309a and 309b, and the top dead center of the movable plate 301 is the position where it abuts against the stoppers 310a and 310b.

[0039] As shown in FIG. 4, the punching device control unit 638 includes a microcomputer (CPU) 701, a RAM 702, a ROM 703, an input / output unit (I / O) 705, a communication interface 706, and a network interface 704. In the conveyance control unit 707, a solenoid SL1 that drives the switching member 217, conveyance drive motors M5, M6, and M7, a sheet end detection sensor 213, and a fan motor that drives a fan are controlled. Also, in the punching drive control unit 708, the punching drive motor M1 is controlled. Various sensor signals are input to the input port of the I / O 705. The output port of the I / O 705 is connected to a control block (not shown) and each drive system connected via various drivers (not shown).

[0040] Incidentally, in this embodiment, the punching unit 220 is configured to be able to change the punching position with respect to the intermediate position in the longitudinal direction of the sheet. The punching unit 220 is configured to vary the punching position, for example, for each sheet within one set in which punching processing is performed.

[0041] In the punching device 200 configured as described above, as shown in FIG. 6, when the leading end of the sheet S is detected by the sheet end detection sensor 213, the sheet S is conveyed by a distance (l - A) according to the sheet size using the sheet leading end detection signal from this sheet end detection sensor 213 as a trigger, and the sheet S is stopped so that the punching forming blade 304 is positioned at a position a predetermined amount A closer to the front side than the distance l from the leading end, which is the intermediate position in the longitudinal direction of the sheet S, and the punching process (first time) is carried out to punch the sheet S.

[0042] After the punching process (first time) is completed, the conveyance of the sheet S is resumed, and the sheet S is stopped again when it has traveled a distance (2A), and the punching process (second time) is carried out to punch the sheet S. Then, after the punching process (second time) is completed, the conveyance of the sheet S is resumed.

[0043] Here, the punching device 200 is configured to change the feed amount when punching the sheet S for each sheet. For example, when the sheet S is plain paper, since its thickness is approximately 0.1 mm, for the second sheet S, after the leading edge of the sheet S is detected by the sheet edge detection sensor 213, the sheet S is stopped at a position where it has traveled a distance of (l - A - 0.1), and the punching process (first time) is performed. Then, after the punching process (first time) is completed, the conveyance of the sheet S is resumed, and the sheet S is stopped again at a position where it has traveled a distance of (2A + 0.2), and the punching process (second time) is performed to punch the sheet S.

[0044] Expressing these relationships by equations, the conveyance amount X1 up to the punching process (first time) is expressed as X1 = (l - A - 0.1*(N - 1)) when the sheet S is the Nth sheet, and the sheet conveyance amount X2 from after the punching process (first time) to the punching process (second time) is expressed as X2 = 2(A + 0.1*(N - 1)). When the sheet S is cardboard, if the coefficient K of (N - 1) in the above equation is set to about 0.2 instead of 0.1, control according to the thickness becomes possible.

[0045] As a result, when, after performing binding processing or the like as necessary on the bundle of sheets S that have been punched by the punching device 220, folding processing is performed, the punching positions of the bundle of sheets S that have been folded in half or the like are such that, as shown in FIGS. 8(a) and 8(b), in the state where the folding processing has been performed, the punching of each sheet S is substantially linear, and it is possible to perform the punching process with high accuracy.

[0046] <Explanation of the finisher> The finisher 100 takes in the sheets from the image forming apparatus main body 600 conveyed via the punching device 200 and performs processing on the taken-in sheets. For example, it performs processing on the sheets such as aligning a plurality of taken-in sheets and bundling them into one sheet bundle, stapling the rear end side of the sheet bundle, sorting processing, non-sorting processing, and binding processing for creating a booklet.

[0047] As shown in FIG. 9, the finisher 100 has a transport path 520 for taking in the sheet conveyed through the punching device 200 into the device interior, and a plurality of transport roller pairs are provided in the transport path 520.

[0048] The switching member 513 provided at the end of the transport path 520 switches the path between the upper sheet discharge path 521 and the lower sheet discharge path 522 connected downstream. The upper sheet discharge path 521 discharges the sheet to the upper stack tray 592. On the other hand, the lower sheet discharge path 522 discharges the sheet to the processing tray 550. The sheet discharged to the processing tray 550 is sequentially aligned in the transport direction by abutting the rear end of the sheet against the rear end reference wall 561 by the return paddle 552 and the return belt 553 and in the width direction by an alignment plate (not shown), and is then accommodated in a bundle. Then, the sheet (sheet bundle) accommodated in a bundle is subjected to sorting processing and stapling processing according to the setting from the operation unit 601, and then is discharged to the stack trays 591 and 592 by the bundle discharge roller pair 551.

[0049] Note that the above-described stapling processing is performed by the stapler 560. The stapler 560 is movable in the width direction orthogonal to the transport direction, and can staple at an arbitrary position of the sheet. The stack trays 591 and 592 are configured to be movable in the vertical direction. The upper stack tray 592 can receive the sheets from the upper sheet discharge path 521 and the processing tray 550, and the lower stack tray 591 can receive the sheets from the processing tray 550. In this way, a large number of sheets can be stacked on the stack trays 591 and 592, and the stacked sheets are regulated and aligned by the rear end guide 593 extending in the vertical direction at their rear ends.

[0050] Next, the configuration of the saddle stitching unit 800 in the finisher 100 will be described. By the switching member 514 provided in the middle of the lower paper discharge path 522, the sheet switched to the right passes through the saddle paper discharge path 523 and is sent to the saddle stitching unit 800. The sheet is delivered to the saddle inlet roller pair 801, and the inlet is selected by the switching member 802 that operates by a solenoid according to the size, and the sheet is carried into the storage guide 803 of the saddle stitching unit 800. The carried-in sheet is conveyed by the sliding roller 804 until the leading end contacts the movable sheet positioning member 805. The saddle inlet roller pair 801 and the sliding roller 804 are driven by a motor M21 (see FIG. 11). Further, at an intermediate position of the storage guide 803, a stapler (not shown) is provided so as to be opposed to each other with the storage guide 803 interposed therebetween. This stapler functions as a stitching means for saddle-stitching a sheet bundle composed of a plurality of sheets. This stapler is divided into a driver 820a that protrudes a needle and an anvil 820b that bends the protruding needle. Note that the sheet positioning member 805 stops at a position where the intermediate position in the sheet longitudinal direction becomes the stitching position of this stapler when the sheet is carried in. The sheet positioning member 805 is movable under the drive of a motor M22 (see FIG. 11) and changes its position according to the sheet size.

[0051] On the downstream side of a stapler (not shown) disposed opposite with the storage guide 803 interposed therebetween, there are provided folding roller pairs 810a and 810b that constitute folding means. At the opposing positions of the folding roller pairs 810a and 810b, there is provided a protruding member 830. This protruding member 830 has its home position at a position retracted from the storage guide 803. The protruding member 830 protrudes toward the sheet bundle stored by the drive of a motor M23 (see FIG. 11), thereby folding the sheet bundle while pushing it into the nip of the folding roller pairs 810a and 810b. The protruding member 830 then returns to the home position again. Note that a sufficient pressure F1 for creasing the bundle is applied by a spring (not shown) between the folding roller pairs 810a and 810b. The folding roller pairs 810a and 810b and the protruding member 830 constitute folding means for folding the sheet bundle in half.

[0052] The creased sheet bundle is discharged to a folded bundle discharge tray 850 via a first folding conveyance roller pair 811a and 811b and a second folding conveyance roller pair 812a and 812b that constitute a square fold processing unit 814. Sufficient pressures F2 and F3 for conveying and stopping the creased sheet bundle are also applied to the first folding conveyance roller pair 811a and 811b and the second folding conveyance roller pair (pressure roller pair) 812a and 812b. The shutter 816 moves in a direction parallel to the storage guide 803 to a position where the leading edge of the sheet does not contact the folding roller pairs 810a and 810b when the sheet is carried into the storage guide 803, and to a position where a path is cleared toward the folding roller pairs 810a and 810b when the protruding member 830 protrudes the sheet bundle. This moving operation is performed by the drive of a motor M26 (see FIG. 11).

[0053] The folding roller pairs 810a and 810b, the first folding conveyance roller pair 811a and 811b, and the second folding conveyance roller pair 812a and 812b rotate at a constant speed by the same motor M24 (see FIG. 11).

[0054] Also, when folding a stack of sheets stapled with a stapler (not shown) disposed opposite with the storage guide 803 in between, after the stapling process, the sheet positioning member 805 is lowered by a predetermined distance from the location during the stapling process so that the stapled position of the stack of sheets comes to the nip position of the folding roller pair 810a, 810b. Thereby, the stack of sheets can be folded with the position where the stapling process was performed as the fold (longitudinal intermediate position).

[0055] Also, the alignment plate pair 815 has a surface that protrudes from the storage guide 803 while surrounding the outer peripheral surfaces of the folding roller pair 810a, 810b, and is an alignment plate pair that aligns the sheets stored in the storage guide 803. The alignment plate pair 815 is driven by a motor M25 (see FIG. 11) and moves in the sandwiching direction with respect to the sheet to perform positioning in the width direction of the sheet.

[0056] With the in-stitching production unit 800 having such a configuration, as shown in FIG. 10, the intermediate position (fold) in the sheet longitudinal direction is in-stitched, and a booklet St that is a stack of sheets folded in half at the in-stitched position is created.

[0057] When the stack of sheets is thick and the folding becomes loose, the created booklet St becomes a booklet with a swollen fold portion Sa as shown in FIG. 13. Conversely, when the stack of sheets is thin and can be folded firmly, the created booklet may have cracks in the fold portion (back) Sb. This cracking becomes particularly prominent when the sheet used for the cover is thick paper. In order to reduce this, grooving may be performed on the fold portion by a grooving unit.

[0058] Next, the square fold processing unit 814 will be described. The square fold processing unit 814 is provided downstream of the folding roller pairs 810a and 810b and the protruding member 830 that constitute the folding means in the sheet conveyance direction. After stopping the tip side (back) of the double-folded double-folded sheet bundle at a predetermined position of the second fold conveyance roller pairs 812a and 812b that constitute the square fold processing unit 814, square fold processing is performed on the back. In this embodiment, the square fold processing unit 814 is incorporated into the finisher 100 as a part of the intermediate binding production unit 800, but it may also be a separate device arranged downstream of the intermediate binding production unit.

[0059] FIG. 12 is a perspective view of the square fold processing unit 814. Second fold conveyance roller pairs (pressing roller pairs) 812a and 812b that grip and press the booklet St from the thickness direction of the booklet, and a back flattening roller 813 that flattens the back of the booklet from a direction orthogonal to the thickness are incorporated in the frame 817. The frame 817 is movably supported by a guide portion (not shown) that guides it so as to be movable parallel to the back of the booklet, and is driven by a drive portion (not shown). As the square fold processing unit 814 moves, while pressing the fold portion of the booklet with the second fold conveyance roller pairs (pressing roller pairs) 812a and 812b, it is flattened with the back flattening roller 813, so that a booklet with a flat back and no bulge as shown in FIG. 14 can be created.

[0060] FIG. 15 is a cross-sectional view when the square fold processing unit 814 is viewed from the side. As described above, the pressure required for the square fold processing for processing the shape of the fold line on the back of the double-folded sheet bundle into a flat state varies depending on the basis weight and number of sheets of the sheet forming the double-folded sheet bundle. In this embodiment, however, it is determined by the stop position of the double-folded sheet bundle when performing the square fold processing, more specifically, the position at which the tip side (back) of the double-folded sheet bundle protrudes from the second fold conveyance roller pairs 812a and 812b. In this embodiment, as shown in FIG. 15, it is assumed that the end from the end of the second fold conveyance roller pairs 812a and 812b to the back flattening roller 813 is configured to be 1.0 mm.

[0061] In the square fold process, the greater the number of sheets forming the double-folded sheet bundle and the greater the basis weight of the sheets, the stronger the pressure required. For example, FIG. 16 shows the stop position when performing the square fold process on a double-folded sheet bundle composed of 5 sheets with a basis weight of 52 gsm. In this embodiment, the leading end side (back) of the double-folded sheet bundle is stopped when it protrudes 1.49 mm from the second fold conveyance roller pair 812a, 812b. That is, in this case, by the square fold process, the back of the double-folded sheet bundle is pressed and crushed (flattened) by (1.49 - 1.0) = 0.49 mm. Further, FIG. 17 shows the stop position when performing the square fold process on a double-folded sheet bundle composed of 30 sheets with a basis weight of 105 gsm. In this embodiment, the leading end side (back) of the double-folded sheet bundle is stopped when it protrudes 4.96 mm from the second fold conveyance roller pair 812a, 812b. That is, in this case, by the square fold process, the back of the double-folded sheet bundle is pressed and crushed (flattened) by (4.96 - 1.0) = 3.96 mm. Thus, when stronger pressure is required, the pressure required for the square fold process is optimized by changing the stop position of the leading end side (back) of the double-folded sheet bundle, such as increasing the amount of protrusion from the second fold conveyance roller pair 812a, 812b.

[0062] As shown in FIG. 11, the finisher control unit includes a microcomputer (CPU) 741, a RAM 742, a ROM 743, an input / output unit (I / O) 745, a communication interface 746, and a network interface 744. Conveyance control is performed by the conveyance control unit 747. In the intermediate processing tray control unit 748, the operation control of the front and rear alignment plates of the processing tray 550 portion, the rotation operation control of the return paddle, and the rotation operation control of the stack discharge roller are respectively controlled by a home position detection sensor and a drive motor. In the binding control unit 749, the clinching, movement, etc. of the stapler are respectively controlled by a home position detection sensor and a movement motor. In the intermediate binding and bookbinding control unit 750, the operation control of the alignment plate, the rotation operation control of the folding conveyance roller, the operation control of the protruding member, the sheet positioning operation control, the stapler clinching operation control, the multi-fold unit operation control, etc. are controlled by a home position detection sensor and a movement motor. Various sensor signals are input to the input port of the I / O 745. The output port of the I / O 745 is connected to a control block (not shown) and each drive system connected via various drivers (not shown).

[0063] However, in the case of the above-described prior art, when a square fold process for processing the shape of the fold line on the back of a two-fold sheet bundle with a perforation process near the back into a flat state is performed, since the amount of crushing of the back of the sheet bundle due to the square fold process is not considered, there is a problem that the perforation position of the two-fold sheet bundle (a booklet subjected to intermediate binding and bookbinding processing) is displaced by the amount of crushing of the back of the sheet bundle due to the square fold process with respect to the expected perforation position.

[0064] Therefore, in the present invention, when performing a square fold process on a two-folded sheet bundle, when performing a plurality of punching processes at positions substantially symmetric with respect to the intermediate position in the longitudinal direction of the sheet, the above-described problem is solved by correcting for the amount of crushing of the back of the sheet bundle due to the square fold process. FIGS. 18, 19, 25, and 26 are flowcharts for explaining the present invention. Unless otherwise specified, the following operations are executed by the CPU 701 (hereinafter referred to as the CPU 701) provided in the punching device control unit 638 or the CPU 741 (hereinafter referred to as the CPU 741) provided in the finisher control unit 636.

[0065] When the printing process is executed, the CPU 701 and the CPU 741 acquire print job information notified from the CPU circuit unit 630 of the image forming apparatus control unit (S101).

[0066] Subsequently, when the sheet is discharged from the image forming apparatus main body 600 to the punching device 200, the CPU 701 receives the sheet and conveys the sheet into the punching device 200 (S102).

[0067] The CPU 701 determines whether or not to perform a punching process on the sheet to be conveyed from the job information acquired in S101 (S103). If it is determined not to perform the punching process (S103: N), the process proceeds to S105. If it is determined to perform the punching process (S103: Y), the CPU 701 stops the sheet at a predetermined position on the punching path B in S104, and then performs a punching process on the stopped sheet by the punching motor M1. The details of this punching process will be described later.

[0068] Thereafter, the CPUs 701 and 741 determine, at S105, whether the discharge destination of the sheet is the saddle tray 850. If it is determined that the discharge destination is not the saddle tray 850 (S105: N), then further at S107, they determine whether the discharge destination is the upper stack tray 592. If it is determined that the discharge destination is the upper stack tray 592 (S107: Y), the CPUs 701 and 741 re-convey the stopped sheet, discharge it to the upper stack tray 592 (S108), and end the process. Also, if it is determined at S107 that the discharge destination is the lower stack tray 591 (S107: N), the CPUs 701 and 741 re-convey the stopped sheet, discharge it to the lower stack tray 591 (S109), and end the process.

[0069] On the other hand, if it is determined at S105 that the discharge destination of the sheet is the saddle tray 850 (S105: Y), the stopped sheet is re-conveyed and accumulated in the saddle processing tray (S106) to form a sheet bundle. Further, the CPU 741 determines, at S110, whether the accumulated sheet is the last sheet of the part.

[0070] If it is determined at S110 that the accumulated sheet is not the last sheet of the part (S110: N), the process ends as it is. If it is determined that it is the last sheet of the part (S110: Y), then subsequently, it is determined whether to perform binding processing on the formed sheet bundle (S111).

[0071] If it is determined at S111 that binding processing is to be performed (S111: Y), the CPU 741 performs binding processing on the sheet bundle with a stapler (S112) and advances the process to S113. On the other hand, if it is determined at S111 that binding processing is not to be performed (S111: N), the CPU 701 advances the process to S113 without performing binding processing on the sheet bundle.

[0072] Thereafter, the CPU 741 performs pushing processing on the sheet bundle at S113 and folding processing at S114 to form a double-folded sheet bundle.

[0073] Subsequently, the CPU 741 determines whether to perform a square fold process on the double-folded sheet bundle from the job information obtained in S101 (S115). If it is determined not to perform the square fold process on the double-folded sheet bundle (S115: N), the CPU 741 discharges the double-folded sheet bundle to the saddle tray 850 in S117 without performing the square fold process and ends the process. On the other hand, if it is determined to perform the square fold process (S115: Y), the CPU 741 performs the square fold process in S116 and then discharges the double-folded sheet bundle to the saddle tray 850 in S117 to end the process.

[0074] Next, the punching process in the present invention will be described with reference to the flowcharts of FIGS. 19, 25, and 26.

[0075] In the punching process of the present invention, first, when the CPU 701 detects the leading edge of the sheet with the sheet edge detection sensor 213 (S201), it performs punching position adjustment (first time) in S202 and calculates the sheet conveyance distance X1' (stop position) from the sheet edge detection sensor 213 for performing the punching process (first time).

[0076] In the punching position adjustment (first time), first, the CPU 701 calculates the sheet conveyance distance X1 after detecting the leading edge of the sheet with the sheet edge detection sensor 213 in the same manner as in the prior art in S301. At this time, the conveyance amount X1 up to the punching process (first time) is expressed as X1 = (l - A - 0.1 * (N - 1)) when the sheet S is the Nth sheet, as described above. For example, when the sheet is cardboard instead of plain paper, if the coefficient K of (N - 1) in the above formula is set to about 0.2 instead of 0.1, control according to the thickness becomes possible.

[0077] Subsequently, at S302, the CPU 701 determines whether to perform a square fold process on the double-folded sheet bundle. If it is determined not to perform the square fold process (S302: N), the sheet conveyance distance X1' (stop position) from the sheet edge detection sensor 213 for performing the first punching process is determined as the final sheet conveyance distance X1' (stop position) without any particular correction, using the sheet conveyance distance X1 calculated above as it is (S304).

[0078] On the other hand, if it is determined at S302 to perform the square fold process (S302: Y), the CPU 701 corrects by the distance of the back of the double-folded sheet bundle (crushing amount O) crushed by the square fold process from the job information acquired at S101, and determines the sheet conveyance distance X1' (stop position) from the sheet edge detection sensor 213 for performing the first punching process (the sheet conveyance distance X1' at this time is expressed as X1' = X1 - crushing amount O). Also, as described above, the crushing amount O is 0.49 mm in the case of performing the square fold process on a double-folded sheet bundle composed of 5 sheets with a basis weight of 52 gsm, and 3.96 mm in the case of performing the square fold process on a double-folded sheet bundle composed of 30 sheets with a basis weight of 105 gsm. In this embodiment, it is assumed that the sheet conveyance distance X1' is corrected by the amount of this crushing amount O.

[0079] At S202, when the sheet conveyance distance X1' is determined, the CPU 701 conveys the sheet by the sheet conveyance distance X1' at S203 and then stops the sheet, and at S204, performs the first punching process on the stopped sheet.

[0080] When the first punching process is performed on the sheet at S204, the CPU 701 starts re-conveying the sheet at S205, and subsequently, calculates the sheet conveyance distance X2' (stop position) for performing the second punching process at S206.

[0081] In the perforation position adjustment (the second time), first, at S401, the CPU 701 calculates the sheet conveyance distance X2 after performing the perforation process (the first time) in the same manner as the prior art. At this time, the conveyance amount X2 up to the perforation process (the second time) is expressed as X2 = 2(A + 0.1*(N−1)) when the sheet S is the Nth sheet, as described above. Note that, for example, when the sheet is not plain paper but thick paper, if the coefficient K of (N - 1) in the above formula is set to about 0.2 instead of 0.1, control according to the thickness becomes possible.

[0082] Subsequently, at S402, the CPU 701 determines whether to perform a square fold process on the double-folded sheet bundle. If it is determined not to perform the square fold process (S402: N), the sheet conveyance distance X2' (stop position) for performing the perforation process (the second time) is determined as the final sheet conveyance distance X2' (stop position) without any particular correction process, just using the sheet conveyance distance X2 calculated above (S404).

[0083] On the other hand, if it is determined at S402 to perform the square fold process (S402: Y), the CPU 701 corrects by the amount of the distance (crushing amount O) of the back of the double-folded sheet bundle crushed by the square fold process from the job information acquired at S101, and determines the sheet conveyance distance X2' (stop position) for performing the perforation process (the second time) (the sheet conveyance distance X2' at this time is expressed as X2' = X2 + crushing amount O). Also, as described above, the crushing amount O is 0.49 mm in the case of performing the square fold process on a double-folded sheet bundle composed of 5 sheets of 52 gsm basis weight, and 3.96 mm in the case of performing the square fold process on a double-folded sheet bundle composed of 30 sheets of 105 gsm basis weight. In this embodiment, it is assumed that the sheet conveyance distance X2' is corrected by the amount of this crushing amount O.

[0084] In S206, when the sheet conveyance distance X2’ is determined, the CPU 701 stops the sheet after conveying the sheet by the sheet conveyance distance X2’ in S207, and in S208, performs a punching process (second time) on the stopped sheet. Then, in S209, the sheet is conveyed again and the punching process is completed.

[0085] As described above, in the present invention, when performing a square fold process on a double-folded sheet bundle, when performing a plurality of punching processes at positions substantially symmetric with respect to the intermediate position in the longitudinal direction of the sheet, by correcting for the amount of crushing of the back of the sheet bundle due to the square fold process, as shown in FIG. 24, it is possible to prevent the punching positions of the double-folded sheet bundle (a booklet subjected to saddle-stitching binding) from shifting.

[0086] Note that the present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the scope of the present invention. All technical matters included in the technical idea described in the claims are the subject of the present invention. The above embodiments are illustrative examples, but those skilled in the art can realize various alternative examples, correction examples, modification examples, or improvement examples from the content disclosed in this specification, and these are included in the technical scope described in the appended claims.

Explanation of Reference Numerals

[0087] S Sheet Sb Fold portion (back) St Double-folded sheet bundle (booklet) 100 Finisher (component of post-processing device) 200 Punching device (component of post-processing device) 217 Switching member 220 Punching unit 600 Image forming apparatus main body 601 Operation unit 630 CPU circuit unit 635 Printer control unit 636 Finisher control unit 638 Punching device control unit 800 Saddle-stitching binding unit Folding roller pair 810a, 810b First folding conveyance roller pair 811a, 811b Second folding conveyance roller pair 812a, 812b Back pressing roller 813 Square fold processing unit 814 Alignment plate pair 815 Stapler 820 Protruding member 830

Claims

1. In an image forming system including a forming device that forms an image on a sheet, a sheet post-processing device and a sheet stacking device that perform post-processing on the sheet on which the image has been formed, perforating means for perforating a predetermined portion of the sheet on which the image has been formed; sheet stacking means for sequentially stacking the sheet on which the image has been formed or the perforated sheet to generate a sheet bundle; folding means for performing a center folding process on the sheet bundle to form a fold line and generating a double-folded sheet bundle; pressing means for pressing the back of the double-folded sheet bundle generated by the folding means and performing a pressing process for processing the back of the sheet bundle into a flat shape; control means for controlling the perforating means and the pressing means, wherein the control means makes the distance from the fold line of the sheet bundle in the perforating process by the perforating means for the sheet bundle on which the pressing process is performed longer than the distance from the fold line to the perforation position in the perforating process for the sheet bundle on which the pressing means is not performed. An image forming system characterized by this.

2. The control means recognizes the number of sheets constituting the sheet bundle formed by the stacking means, determines whether the number of sheets forming the sheet bundle exceeds a preset reference number or is less than the reference number, and makes the distance from the fold line of the sheet bundle in the perforating process by the perforating means for the sheet bundle exceeding the reference number longer than the distance from the fold line to the perforation position in the perforating process for the sheet bundle less than the reference number. The image forming system according to claim 1, characterized by this.

3. The control means recognizes the number of sheets constituting the sheet bundle formed by the stacking means, determines whether the number of sheets forming the sheet bundle exceeds a preset reference number or is less than the reference number, and makes the distance from the fold line of the sheet bundle in the perforating process by the perforating means for the sheet bundle exceeding the reference number longer than the distance from the fold line to the perforation position in the perforating process for the sheet bundle less than the reference number. The image forming system according to claim 1, characterized by this.

4. The control means recognizes the basis weight of the sheet bundle formed by the stacking means, determines whether the basis weight of the sheet bundle exceeds a preset reference value or is less than the reference value, The image forming system according to claim 1, wherein a distance from a fold of the sheet bundle to a punching position in the punching process of the sheet bundle exceeding the reference value by the punching means is made longer than a distance from the fold to the punching position in the punching process of the sheet bundle less than the reference value.

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