Image formation system with sheet processing device

Abstract

To prevent the occurrence of damage such as crushing of punching holes on a two-folded sheet bundle and breakage near a back part in sheet processing that can perform square-folding processing to make the shape of the fold of the back part into a planar state for the sheet bundle subjected to two-folding and punching processing.SOLUTION: An image formation system includes: 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 and on which the image is formed 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 recognizes whether or not the sheet bundle has been punched by the punching means, and performs operation control on whether or not the pressing processing is performed on the punched sheet bundle by the pressing means depending on various conditions of the sheet bundle.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 image-formed sheets to form a sheet bundle, and performs punching processing on the folded sheet bundle to create a booklet after folding the sheet bundle in half.

Background Art

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

[0003] In addition, there are also known sheet processing apparatuses that form an image on a large-size sheet, cut the center of the sheet in the longitudinal direction along the sheet width direction to obtain two sheets, fold the sheet bundle in half (center fold), perform punching processing along the center fold line, perform center binding processing to produce a book (create a booklet), and a sheet processing apparatus called a walnut 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 apparatus, sheet processing apparatus, and sheet stacking apparatus.

[0005] In addition, among sheet processing apparatuses, there is a type that first performs stapling processing or punching processing at the longitudinal middle position of the sheet bundle, then bends the sheet bundle along its longitudinal middle position, and finally applies pressure to the longitudinal middle position of the bent sheet bundle to perform sheet bundle processing (bookbinding processing).

[0006] However, for example, when the longitudinal middle 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 flatten the back of the sheet bundle (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 that performs a square fold process of applying pressure in a direction perpendicular to the back of the sheet bundle and forcibly forming a corner (fold) on the back of the sheet bundle is known (see, for example, Patent Document 1).

[0008] By performing the square fold process on the bent sheet bundle in this way, not only does the appearance of the sewn-bound product 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 bending 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 bending process.

[0011] Therefore, in the square folding process of the sheet bundle, if pressure treatment according to the characteristics of the sheets constituting the sheet bundle is not performed, the form of the sheet bundle to be bookbound may be impaired. For example, when performing square folding on a sheet bundle of thin sheets with excessive pressure, 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 square folding on a sheet bundle to be bookbound 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 appropriate square force treatment 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 middle binding processing device that folds a sheet bundle in half (center fold) and performs punching processing along the center fold line, when performing complicated punching operations for filing sheets and middle binding bookbinding operations, an image forming system is disclosed that performs punching processing and / or stapling processing 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 center line of the sheets, and then perform middle binding bookbinding processing. For example, it is possible to generate a bookbinding sheet bundle as shown in FIG. 24 of the present application.

[0015] However, in such a conventional apparatus, when perforating the sheet bundle, the deviation of the hole position is not taken into account. Therefore, when the plurality of sheets that have been perforated are overlapped with each other and then folded in half to form a sheet bundle, for example, as shown in FIGS. 7(a) and 7(b) of the present application, the position of the perforation holes gradually deviates by the thickness of the sheet, and the diameter of the perforation holes formed in the sheets constituting the sheet bundle becomes substantially smaller. This is a problem.

[0016] In order to solve this problem, an apparatus is also known that corrects the position where the perforation process is performed on the sheet so as to change the deviation of the perforation holes in 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, a strong pressure is applied to the back of the double-folded sheet bundle from the vertical direction. Therefore, the perforation holes in the double-folded sheet bundle (after the saddle-stitch binding process) are crushed, or damage such as tearing near the back occurs, and the quality of the double-folded sheet bundle as a booklet cannot be maintained. This is a problem.

[0019] Therefore, an object of the present invention is to provide a sheet processing apparatus capable of performing a square fold process on a folded and perforated sheet bundle to process the shape of the fold on the back thereof into a flat state, without causing damage such as perforation hole collapse or tearing near the back of the double-folded sheet bundle (a booklet subjected to saddle stitching).

Means for Solving the Problems

[0020] To achieve the above object, the present invention provides an image forming system including an image forming apparatus that forms an image on a sheet, a sheet post-processing apparatus and a sheet stacking apparatus that perform post-processing on the image-formed sheet, a punching means that punches a predetermined portion of the image-formed sheet, a sheet stacking means that sequentially stacks the image-formed sheet or the punched image-formed sheet to generate a sheet bundle, a folding means that performs a middle folding process on a position substantially symmetric with respect to the intermediate position in the longitudinal direction of the sheet bundle to generate a double-folded sheet bundle, a pressing means that presses the back of the double-folded sheet bundle generated by the folding means to perform a pressing process for processing the back of the sheet bundle into a flat shape, and a control means that controls the punching means and the pressing means. The control means recognizes whether the sheet bundle has been punched by the punching means, and when the sheet bundle has been punched by the punching means, performs an operation control on whether to perform a pressing process by the pressing means on the punched sheet bundle according to the situation of the sheet bundle. This is the feature of the present invention.

[0021] Here, a first control example of the operation control on whether to perform a pressing process by the pressing means on the punched sheet bundle includes a reference distance recognition means that recognizes whether the distance from the back end of the double-folded sheet bundle generated by the folding means to the punching position of the punched sheet generated by the punching means is less than a reference value. When the control means recognizes that the distance between the punching position applied to the double-folded sheet bundle and the back end of the double-folded sheet bundle is less than the reference value, the control means controls not to perform the pressing operation of the pressing means.

[0022] Also, a second control example of the operation control for whether or not to perform the pressing process on the perforated sheet bundle by the pressing means recognizes the number of sheets constituting the sheet bundle formed by the stacking means, and the control means recognizes whether the number of sheets forming the sheet bundle exceeds a preset reference number of sheets or is less than the reference number of sheets. In the case of a sheet bundle exceeding the reference number of sheets, the pressing means is controlled so as not to perform the pressing process by the pressing means.

[0023] And a third control example of the operation control for whether or not to perform the pressing process on the perforated sheet bundle by the pressing means includes a reference basis weight recognition means for recognizing whether or not the basis weight of the sheet bundle formed by the stacking means is less than a reference value. When the control means recognizes that the basis weight of the sheet bundle is less than the reference value by the reference basis weight recognition means, the control means controls so as not to perform the pressing process by the pressing means.

[0024] Furthermore, a fourth control example of the operation control for whether or not to perform the pressing process on the perforated sheet bundle by the pressing means includes a reference number of perforations recognition means for recognizing whether or not the number of perforations of the perforated sheet generated by the perforating means is less than a reference number. When the control means recognizes that the number of perforations of the perforated sheet of the sheet bundle is less than the reference number, the control means controls so as not to perform the pressure control by the pressing means.

Advantages of the Invention

[0025] According to the present invention, when a perforation process is performed near the back of a double-folded sheet bundle, by performing whether or not to perform a square fold process on the double-folded sheet bundle according to various situations of the sheet bundle, it is possible to prevent damage such as collapse of the perforation holes and tearing near the back of the double-folded sheet bundle (a booklet subjected to the saddle-stitching binding process).

Brief Description of the Drawings

[0026]

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[0027] Hereinafter, with reference to the drawings, exemplary preferred embodiments of the present invention will be described in detail. However, dimensions, materials, shapes, relative arrangements, etc. of the components described in the following embodiments are appropriately changed.

[0028] <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 punching 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 punching 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 punching 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 near side) of the image forming apparatus, and the back side of the apparatus is referred to as the far side. FIG. 1 shows the configuration of the image forming apparatus as viewed from the near side of the apparatus. The punching apparatus 200 and the finisher 100 are connected to the side portion of the image forming apparatus main body 600.

[0029] Sheets S fed 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 single-sided image forming mode, they are directly discharged outside the apparatus main body from the discharge roller pair 907. In the case of 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 conveyance direction of the sheet exceeds the reverse switching section P, the reversing roller 905 is reversely rotated and 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.

[0030] 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 punching device control unit 638 and the finisher control unit 636 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 side of the punching device 200, or the punching device 200 may be controlled by the control means on the side of the finisher 100.

[0031] 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.

[0032] The punching device control unit 638 is mounted on the punching device 200 and controls the driving 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 controls the driving 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.

[0033] 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, settings for saddle stitching binding as shown in FIG. 20 are 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.

[0034] <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 delivers the sheets to the downstream finisher 100 without processing. These paths are switched by a switching member 217.

[0035] 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.

[0036] 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 by the inlet sensor 201.

[0037] 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.

[0038] 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 is detected by the sheet edge detection sensor 213. 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.

[0039] FIG. 5 is a cross-sectional view of the perforating unit 220 when 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.

[0040] 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, M7, a sheet edge detection sensor 213, and a fan motor that drives a fan are controlled. Also, in the punching drive control unit 708, a 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).

[0041] By the way, in this embodiment, the punching unit 220 is configured to be able to change the punching position with respect to the center line of the sheet, and the punching unit 220 is configured to make the punching positions different for each sheet within one set in which punching processing is performed, for example.

[0042] 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 edge detection sensor 213, using the sheet leading end detection signal from this sheet edge detection sensor 213 as a trigger, the sheet S is conveyed by a distance (l - A) according to the sheet size, and the sheet S is stopped so that the punching forming blade 304 is 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 punching processing (first time) is carried out to make a punching hole in the sheet S.

[0043] After the punching processing (first time) is completed, the conveyance of the sheet S is restarted, and the sheet S is stopped again at a position where it has traveled a distance (2A), and punching processing (second time) is carried out to make a punching hole in the sheet S. Then, after the punching processing (second time) is completed, the conveyance of the sheet S is restarted.

[0044] Here, the punching device 200 is configured to change the feed amount during punching the sheet S for each sheet. For example, when the sheet S is a plain sheet, since its thickness is approximately 0.1 mm, for the second sheet S, after the leading end of the sheet S is detected by the sheet end 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. 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 holes in the sheet S.

[0045] Expressing these relationships by equations, the conveyance amount X1 until 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) until the punching process (second time) is expressed as X2 = 2(A + 0.1*(N - 1)). When the sheet S is a thick sheet, 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.

[0046] As a result, when the folded sheet S bundle that has been punched by the punching device 220 is subjected to intermediate binding processing or the like as necessary and then subjected to the folding process, the punching positions of the folded sheet S bundle that has been folded into two folds or the like are, as shown in FIGS. 8(a) and 8(b), in a state where the folding process is performed, and the punching holes of each sheet S are substantially linear, and it is possible to perform the punching process with high accuracy.

[0047] <Description of the finisher> The finisher 100 takes in the sheet from the image forming apparatus main body 600 conveyed through the punching device 200 and processes the taken-in sheet. For example, it performs processes on the sheet 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 process, non-sorting process, and intermediate binding process for creating a booklet.

[0048] As shown in FIG. 9, the finisher 100 has a conveyance path 520 for taking in the sheet conveyed through the punching device 200 into the device interior, and a plurality of conveyance roller pairs are provided in the conveyance path 520.

[0049] The switching member 513 provided at the end of the conveyance path 520 switches the path between the upper discharge sheet path 521 and the lower discharge sheet path 522 connected downstream. The upper discharge sheet path 521 discharges the sheet to the upper stack tray 592. On the other hand, the lower discharge sheet path 522 discharges the sheet to the processing tray 550. The sheet discharged to the processing tray 550 is sequentially aligned in a bundle while the rear end of the sheet is abutted against the rear end reference wall 561 by the return paddle 552 and the return belt 553 and widthwise alignment is performed by an alignment plate (not shown). 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 thereafter, is discharged to the stack trays 591 and 592 by the bundle discharge sheet roller pair 551.

[0050] Note that the above-described stapling processing is performed by the stapler 560, and the stapler 560 is movable in the width direction orthogonal to the conveyance 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, and the upper stack tray 592 can receive the sheet from the upper discharge sheet path 521 and the processing tray 550, and the lower stack tray 591 can receive the sheet 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.

[0051] Next, the configuration of the saddle stitching main unit 800 in the finisher 100 will be described. The sheet switched to the right by the switching member 514 provided in the middle of the lower discharge sheet path 522 passes through the saddle discharge sheet path 523 and is sent to the saddle stitching main unit 800. The sheet is delivered to the saddle inlet roller pair 801, and the carrying-in port is selected by the switching member 802 operated by a solenoid according to the size, and the sheet is carried into the storage guide 803 of the saddle stitching main unit 800. The carried-in sheet is conveyed by the sliding roller 804 until the tip 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). Also, in the middle position of the storage guide 803, a stapler (not shown) arranged to face each other with the storage guide 803 interposed therebetween is provided. The stapler functions as a saddle stitching means for saddle-stitching a sheet bundle composed of a plurality of sheets. The 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 middle 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.

[0052] On the downstream side of the stapler, a pair of folding rollers 810a and 810b constituting folding means are provided, and a protruding member 830 is provided at the opposing position of the pair of folding rollers 810a and 810b. This protruding member 830 has its home position at a position retracted from the storage guide 803. The protruding member 830 protrudes toward the stored sheet bundle by the drive of a motor M23 (see FIG. 11), and folds the sheet bundle while pushing it into the nip of the pair of folding rollers 810a and 810b. The protruding member 830 then returns to the home position again. Note that a sufficient pressure F1 for making a crease in the bundle is applied between the pair of folding rollers 810a and 810b by a spring (not shown). The pair of folding rollers 810a and 810b and the protruding member 830 constitute folding means for folding the sheet bundle in half.

[0053] The folded sheet bundle is discharged to the folding bundle discharge tray 850 via the first folding conveyance roller pair 811a, 811b and the second folding conveyance roller pair 812a, 812b that constitute the square fold processing unit 814. Sufficient pressures F2 and F3 for conveying and stopping the folded sheet bundle are also applied to the first folding conveyance roller pair 811a, 811b and the second folding conveyance roller pair (pressure roller pair) 812a, 812b. When a sheet is carried into the storage guide 803, 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 pair 810a, 810b, and when the protruding member 830 protrudes the sheet bundle, it moves to a position that creates a path toward the folding roller pair 810a, 810b. This moving operation is performed by driving a motor M26 (see FIG. 11).

[0054] The folding roller pair 810a, 810b, the first folding conveyance roller pair 811a, 811b, and the second folding conveyance roller pair 812a, 812b rotate at a constant speed by the same motor M24 (see FIG. 11).

[0055] When folding a sheet bundle stapled with a stapler, after the stapling process is completed, 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 sheet bundle comes to the nip position of the folding roller pair 810a, 810b. Thereby, the sheet bundle can be folded around the position where the stapling process was performed.

[0056] The alignment plate pair 815 has a surface that protrudes into 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.

[0057] With the center stitching production unit 800 configured as described above, as shown in FIG. 10, the middle position in the sheet longitudinal direction is center stitched, and a booklet St which is a two-folded sheet bundle at the center stitched position is created.

[0058] When the sheet bundle is thick and the folding is loose, the created booklet St will be a booklet with a bulged folding part Sa as shown in FIG. 13. Conversely, when the sheet bundle is thin and can be firmly folded, the created booklet may have cracks in the folding part (back) Sb. Especially when the sheet used for the front sheet is a thick sheet, this cracking becomes prominent. In order to reduce this, ribbing may be performed on the folding part by a ribbing unit (not shown).

[0059] Next, the square fold processing unit 814 will be described. The square fold processing unit 814 is provided downstream in the sheet conveyance direction of the folding roller pairs 810a, 810b and the protruding member 830 that constitute the folding means. After stopping the front end side (back part) of the two-folded two-folded sheet bundle at a predetermined position of the second fold conveyance roller pairs 812a, 812b that constitute the square fold processing unit 814, square fold processing is performed on the back part. In this embodiment, this square fold processing unit 814 is incorporated into the finisher 100 as a part of the center stitching production unit 800, but it may also be a separate device arranged downstream of the center stitching production unit.

[0060] FIG. 12 is a perspective view of the square fold processing unit 814. Second fold conveyance roller pairs (pressing roller pairs) 812a, 812b that grip and press the booklet St from the booklet thickness direction, and a back flattening roller 813 that flattens the back of the booklet from a direction orthogonal to the thickness are incorporated into the frame 817. And the frame 817 is movably supported by a guide part (not shown) that guides it to be movable parallel to the back of the booklet, and is driven by a drive part (not shown). Along with the movement of the square fold processing unit 814, while pressing the folding part of the booklet with the second fold conveyance roller pairs (pressing roller pairs) 812a, 812b, it is flattened with the back flattening roller 813, so that a booklet with a flat and non-bulged back as shown in FIG. 14 can be created.

[0061] 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 the 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, by how much the leading end side (back) of the double-folded sheet bundle protrudes from the second fold conveyance roller pair 812a and 812b and stops at that position.

[0062] In the square fold processing, the greater the number of sheets forming the double-folded sheet bundle and the greater the basis weight of the sheet, the stronger the pressure required. For example, FIG. 16 shows the stop position when performing the square fold processing 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 at a position protruding 1.49 mm from the second fold conveyance roller pair 812a and 812b. Further, FIG. 17 shows the stop position when performing the square fold processing 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 at a position protruding 4.96 mm from the second fold conveyance roller pair 812a and 812b. Thus, when stronger pressure is required, the pressure required for the square fold processing 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 and 812b.

[0063] 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 bundle discharging sheet roller are respectively controlled by the home position detection sensor and the drive motor. In the binding control unit 749, the clinching, movement, etc. of the stapler are respectively controlled by the home position detection sensor and the movement motor. In the half-binding 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 additional folding unit operation control, etc. are controlled by the home position detection sensor and the 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).

[0064] However, when a square fold process is performed on a two-folded sheet bundle with a perforation process near the back, if pressure is applied in a direction perpendicular to the back of the two-folded sheet bundle to process the shape of the fold line on the back into a flat state, there is a problem that damage such as perforation hole collapse or tearing near the back of the two-folded sheet bundle occurs, and the quality of the two-folded sheet bundle as a booklet cannot be maintained.

[0065] Therefore, in the present invention, when a perforation process is performed near the back of a two-folded sheet bundle, the above-described problem is solved by prohibiting the square fold process on the two-folded sheet bundle. FIGS. 18 and 19 are flowcharts for explaining the present invention. Unless otherwise specified, the following operations are executed by the CPU 701 (hereinafter referred to as CPU 701) provided in the perforating device control unit 638 or the CPU 741 (hereinafter referred to as CPU 741) provided in the finisher control unit 636.

[0066] When printing processing is executed, the CPUs 701 and 741 acquire print job information notified from the CPU circuit section 630 of the image forming apparatus control section (S101).

[0067] Subsequently, when a 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).

[0068] The CPU 701 determines whether to perform punching processing on the sheet to be conveyed based on the job information acquired in S101 (S103). If it is determined not to perform punching processing (S103: N), the process proceeds to S105. If it is determined to perform punching processing (S103: Y), the CPU 701 stops the sheet at a predetermined position on the punching path B in S104, and then performs punching processing on the stopped sheet by the punching motor M1.

[0069] Thereafter, the CPUs 701 and 741 determine in 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 in S107, it is determined 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 and discharge it to the upper stack tray 592 (S108), and the process ends. Also, if it is determined in S107 that the discharge destination is the lower stack tray 591 (S107: N), the CPUs 701 and 741 re-convey the stopped sheet and discharge it to the lower stack tray 591 (S109), and the process ends.

[0070] On the other hand, if it is determined in 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 in S110 whether the accumulated sheet is the last sheet.

[0071] In S110, if it is determined that the stacked sheet is not the final sheet of the part (S110: N), the process ends as it is. If it is determined that the sheet is the final sheet of the part (S110: Y), then it is subsequently determined whether to perform binding processing on the formed stack of sheets (S111).

[0072] In S111, if it is determined to perform binding processing (S111: Y), the CPU 741 performs binding processing on the stack of sheets with a stapler (S112) and advances the process to S113. On the other hand, in S111, if it is determined not to perform binding processing (S111: N), the CPU 701 advances the process to S113 without performing binding processing on the stack of sheets.

[0073] Thereafter, the CPU 741 performs punching processing on the stack of sheets in S113 and folding processing in S114 to form a double-folded stack of sheets.

[0074] Subsequently, the CPU 741 determines whether to perform square fold processing on the double-folded stack of sheets from the job information acquired in S101 (S115). If it is determined not to perform square fold processing on the double-folded stack of sheets (S115: N), the double-folded stack of sheets is discharged to the saddle tray 850 in S119 and the process ends. On the other hand, if it is determined to perform square fold processing (S115: Y), the CPU 741 performs square fold execution determination processing described later in S116.

[0075] In the square fold execution determination processing, if it is determined that square fold processing can be performed on the double-folded stack of sheets (S117: Y), the CPU 741 performs square fold processing on the double-folded stack of sheets in S118, and then discharges the double-folded stack of sheets to the saddle tray 850 in S119 to end the process. Conversely, if it is determined that square fold processing is not possible (S117: N), the CPU 741 discharges the double-folded stack of sheets to the saddle tray 850 as it is in S119 without performing square fold processing to end the process.

[0076] Next, the square foldability determination process will be described using the flowchart of FIG. 19.

[0077] In the square foldability determination process, first, it is determined whether or not a perforation process has been performed near the back of the double-folded sheet bundle (S201). If it is determined that the perforation process has not been performed (S201: N), the CPU 741 determines in S208 that the square fold process can be performed on the double-folded sheet bundle and ends the process.

[0078] If it is determined in S201 that punching processing has been performed near the back of the double-folded sheet bundle (S201: Y), the CPU 741 determines in S202 whether the square fold prohibition mode (a mode that prohibits square fold processing when punching processing has been performed near the back of the double-folded sheet bundle) is set on the setting screen of the operation unit 601. In this embodiment, it is assumed that the square fold prohibition mode is set according to the following procedure. The user can individually select the saddle-stitching process, punching process, and square fold process on the setting screen for saddle-stitching binding as shown in FIG. 20 displayed on the operation unit 601. However, as described above, if square fold processing is performed on a double-folded sheet bundle with punching processing near the back, there is a risk that damage such as punching hole collapse or tearing near the back of the double-folded sheet bundle will occur and the quality as a booklet cannot be maintained. Therefore, when the punching process and the square fold process are simultaneously selected on the setting screen for saddle-stitching binding, a screen as shown in FIG. 21 is further displayed on the operation unit 601 to allow the user to select whether to prohibit square fold processing for the booklet on which punching processing has been performed. At this time, if the user selects to prohibit square fold processing, it is assumed that the square fold prohibition mode is set. If the CPU 741 determines in S202 that the square fold prohibition mode is set (S202: Y), the CPU 741 determines in S207 that square fold processing cannot be performed on the double-folded sheet bundle and ends the process. In this embodiment, the case where the square fold prohibition mode is selected on the setting screen of the operation unit 601 is shown. However, for example, it is also possible to make it impossible to simultaneously select punching processing near the back of the double-folded sheet bundle and square fold processing on the operation unit 601, or to display a process that allows the user to select to enable it as shown in FIG. 22.

[0079] When the CPU 741 determines that the square fold prohibition mode is not set on the setting screen of the operation unit 601 (S202: N), at S203, it determines whether the distance from the back end of the double-folded sheet bundle to the punching position is less than the reference value. Generally, when performing a square fold process on the back end of a double-folded sheet bundle, the shorter the distance from the back end of the double-folded sheet bundle to the punching position, the more likely it is that damage such as punching hole collapse or tearing near the back will occur in the double-folded sheet bundle. In this embodiment, this reference value is set to 6.1 mm.

[0080] If, at S203, it is determined that the distance from the back end of the double-folded sheet bundle to the punching position is less than the reference value (6.1 mm) (S203: Y), the CPU 741 determines at S207 that the square fold process cannot be performed on the double-folded sheet bundle and ends the process. On the other hand, if it is determined that the distance from the back end of the double-folded sheet bundle to the punching position is greater than or equal to the reference value (6.1 mm) (S203: N), the CPU 741 advances the process to S204.

[0081] After that, at S204, the CPU 741 determines whether the number of sheets constituting the double-folded sheet bundle is less than the reference number. Generally, when performing a square fold process on the back end of a double-folded sheet bundle, the smaller the number of sheets in the double-folded sheet bundle, the more likely it is that damage such as punching hole collapse or tearing near the back will occur in the double-folded sheet bundle. In this embodiment, this reference number is set to 10 sheets.

[0082] If, at S204, it is determined that the number of sheets in the double-folded sheet bundle is equal to the reference number (10 sheets) (S204: Y), the CPU 741 determines at S207 that the square fold process cannot be performed on the double-folded sheet bundle and ends the process. On the other hand, if it is determined that the number of sheets in the double-folded sheet bundle is greater than or equal to the reference number (10 sheets) (S204: N), the CPU 741 advances the process to S205.

[0083] Thereafter, the CPU 741 determines whether the total floor area of the sheets constituting the double-folded sheet bundle is less than the reference value at S205. Generally, when performing a square fold process on the back end of the double-folded sheet bundle, the smaller the total floor area of the double-folded sheet bundle, the more likely it is that damage such as perforation hole collapse or tearing near the back will occur. Although the floor area varies depending on the type of sheet, in this embodiment, this reference value is set to 130 g (equivalent to 10 sheets of A3-sized sheets with a floor area of 105 gsm).

[0084] If it is determined at S205 that the total floor area of the double-folded sheet bundle is less than the reference value (130 g) (S205: Y), the CPU 741 determines at S207 that the square fold process cannot be performed on the double-folded sheet bundle and ends the process. On the other hand, if it is determined that the total floor area of the double-folded sheet bundle is equal to or greater than the reference value (130 g) (S205: N), the CPU 741 proceeds with the process to S206.

[0085] Thereafter, the CPU 741 determines at S206 whether the number of perforation holes made in the double-folded sheet bundle is equal to or greater than the reference number. Generally, when performing a square fold process on the back end of the double-folded sheet bundle, the more perforation holes are made near the back of the double-folded sheet bundle, the more likely it is that damage such as perforation hole collapse or tearing near the back will occur. FIGS. 23(a) to (i) are diagrams showing the patterns of perforation holes made near the back of the double-folded sheet bundle. For example, it is obvious that damage such as perforation hole collapse or tearing near the back is more likely to occur in FIGS. 23(a) to (e) than in FIGS. 23(f) to (i). In this embodiment, this reference number is set to 10 locations.

[0086] In S206, when it is determined that the number of perforation holes made in the double-folded sheet bundle is equal to or greater than the reference number (10 places) (S206: Y), the CPU 741 determines in S207 that square folding processing cannot be performed on the double-folded sheet bundle and ends the process. On the other hand, when it is determined that the number of perforation holes made in the double-folded sheet bundle is less than the reference number (10 places) (S206: N), the CPU 741 determines in S207 that square folding processing can be performed on the double-folded sheet bundle and ends the process.

[0087] As described above, in the present invention, when perforation processing is performed near the back of the double-folded sheet bundle, damage such as the collapse of the perforation holes or tearing near the back of the double-folded sheet bundle (the booklet subjected to the saddle-stitching binding process) can be prevented by not performing square folding processing on the double-folded sheet bundle.

[0088] 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, and those skilled in the art can realize various alternative examples, modification examples, variation 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

[0089] S sheet Sb folding part (back) St double-folded sheet bundle (booklet) 100 finisher (component of the post-processing device) 200 perforating device (component of the post-processing device) 217 switching member 220 perforating 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 Middle binding production department 810a, 810b Pair of folding rollers 811a, 811b First folding conveyance roller pair 812a, 812b Second folding conveyance roller pair 813 Back pressing roller 814 Square fold processing unit 815 Pair of alignment plates 820 Stapler 830 Protruding member

Claims

1. In an image forming system including a forming device that forms an image on a sheet, a sheet post-processing device that performs post-processing on the image-formed sheet, and a sheet stacking device, a punching means for punching a predetermined portion of the image-formed sheet; a sheet stacking means for sequentially stacking the image-formed sheet or the punched image-formed sheet to generate a sheet bundle; a folding means for performing a middle folding process on the sheet bundle to generate a double-folded sheet bundle; a pressing means for pressing the back of the double-folded sheet bundle generated by the folding means and performing a pressing process for flattening the back of the sheet bundle; a control means for controlling the punching means and the pressing means, wherein the control means recognizes whether the sheet bundle is punched by the punching means, and when the sheet bundle is punched by the punching means, performs an operation control of whether to perform a pressing process by the pressing means on the punched sheet bundle according to the situation of the sheet bundle. An image generation system characterized by this.

2. a reference distance recognition means for recognizing whether the distance from the back end of the double-folded sheet bundle generated by the folding means to the punching position of the punched sheet generated by the punching means is less than a reference value; wherein the control means controls so as not to perform the pressing operation of the pressing means when it is recognized that the distance between the punching position applied to the double-folded sheet bundle and the back end of the double-folded sheet bundle is less than the reference value. The image generation system according to Claim 1.

3. recognize the number of sheets constituting the sheet bundle formed by the stacking means, wherein the control means recognizes whether the number of sheets forming the sheet bundle exceeds a preset reference number or is less than the reference number, and controls the pressing means so as not to perform the pressing process by the pressing means in the case of a sheet bundle exceeding the reference number. The image generation system according to Claim 1.

4. a reference basis weight recognition means for recognizing whether the basis weight of the sheet bundle formed by the stacking means is less than a reference value; wherein the control means controls so as not to perform the pressing process by the pressing means when it is recognized by the reference basis weight recognition means that the basis weight of the sheet bundle is less than the reference value. The image generation system according to Claim 1.

5. A reference punching number recognition means for recognizing whether the number of punches of the punched sheet generated by the punching means is less than a reference number; The image generation system according to claim 1, wherein when the control means recognizes that the number of punches of the punched sheet of the sheet bundle is less than a reference number, the control means controls not to perform the pressure control by the pressing means. [

6. ] An input means for giving an instruction on whether to execute the punching process and / or whether to execute the pressing process; The image forming system according to any one of claims 1 to 5, wherein the control means preferentially controls the operation of the punching means and the operation of the pre-pressing means according to the instruction of the input means.

Images