Sheet discharge device and sheet post-processing device equipped with the same

Abstract

To provide a sheet discharge device capable of accurately setting the number of folded sheets which are stacked on a discharge tray and regularly stacking the folded sheets with a simple configuration, and a sheet post-processing device equipped with the same.SOLUTION: A sheet post-processing device comprises a sheet conveyance path, a folding unit, a sheet discharge part having a discharge roller pair for discharging a folded sheet, a sheet discharge tray having a tray upper face and a rear wall, a full state detecting sensor for detecting a full state of folded sheets which are stacked on the tray upper face, and a first sheet-pressing member and a second sheet-pressing member for pressing a rear end side and a tip side, respectively, in the discharge direction of the folded sheets which are stacked on the tray upper face. The first sheet-pressing member comes in contact with any position in a range from the center portion in the discharge direction of the folded sheet of the minimum size which is stacked on the tray upper face to the rear wall, at a pressing position extending from above the discharge roller pair to below a lower limit of the detection region, and is retracted from the pressing position when the number of folded sheets stacked on the tray exceeds a predetermined number.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a sheet discharge device that discharges sheets that have been subjected to a folding process to form creases in the sheets, and a sheet post-processing device that includes the sheet discharge device. [Background technology]

[0002] 2. Description of the Related Art There is known a sheet post-processing device that includes a sheet folding device that performs a folding process to form creases in sheets after an image has been formed by an image forming device such as a copying machine or a printer.

[0003] When folded sheets are discharged and stacked on a sheet stacking tray, the thickness of the folded portion of the sheet increases, making it difficult to stack a large number of sheets in an orderly manner. As a result, sheet stacking trays have tended to become larger.

[0004] Patent Document 1 discloses a sheet post-processing device equipped with a paper discharge impeller as a paper discharge means for guiding a bound paper stack to a stacking means. In this sheet post-processing device, one or more paper discharge impellers are provided in the axial direction of a rotation shaft, with blades for discharging the paper stack fixed along the circumferential direction. The paper discharge impellers pinch the bound paper stack while discharging it, allowing a large amount of paper stacks to be efficiently stacked on the stacking means.

[0005] Patent document 2 discloses a sheet stacking device equipped with a sheet pressing means for pressing down sheets stacked on a discharged sheet stacking means from above, which includes a sheet stack pressing arm for pressing down the leading end of the sheet stack discharged onto the stacking tray, and a discharged sheet paddle for pressing down the trailing end of the sheet stack discharged onto the stacking tray. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-62111 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-255431 Summary of the Invention [Problem to be solved by the invention]

[0007] The configuration of Patent Document 1 has a problem in that the configuration of the discharge impeller is complicated, which increases the number of parts and costs.The configuration of Patent Document 2 has a problem in that the discharge sheet paddle is located below the pair of discharge rollers, which requires the discharge sheet paddle to rotate in order to press down the trailing edge of the discharged sheet, which complicates the configuration and drive control.

[0008] In view of the above problems, the present invention aims to provide a sheet discharge device that can improve the number of sheets that can be stacked and the alignment of folded sheets with a simple configuration, and a sheet post-processing device equipped with the same. [Means for solving the problem]

[0009] To achieve the above object, a first aspect of the present invention is a sheet discharge device including a sheet discharge section, a sheet discharge tray, a fullness detection sensor, a first sheet pressing member, and a second sheet pressing member. The sheet discharge section has a pair of discharge rollers that discharge folded sheets. The sheet discharge tray has a tray upper surface on which folded sheets discharged from the sheet discharge section are stacked, and a rear wall portion rising from the upstream end of the tray upper surface in the discharge direction. The fullness detection sensor is provided in the sheet discharge section and detects whether the sheet discharge tray is full of folded sheets by detecting the height of the stacking surface of the folded sheets stacked on the tray upper surface. The fullness detection sensor has a detection area with a predetermined width in the height direction at a detection position in the width direction perpendicular to the discharge direction. The first sheet pressing member comes into contact with folded sheets discharged from the sheet discharge section and presses the trailing end of the folded sheets stacked on the tray upper surface in the discharge direction. The second sheet pressing member presses the leading end of the folded sheets stacked on the tray upper surface in the discharge direction. The first sheet pressing member is positioned outside the detection position in the width direction, and at a pressing position extending from above the pair of discharge rollers to below the lower limit of the detection area, it contacts any position within the range from the center in the discharge direction of the smallest size folded sheets stacked on the top surface of the tray to the rear wall to suppress the bulge of the folded sheets, and when the number of stacked folded sheets exceeds a predetermined number, it retreats from the pressing position to allow the stacking surface of the folded sheets to rise. [Effects of the Invention]

[0010] According to the first configuration of the present invention, the vicinity of the trailing edge of the folded sheet can be reliably pressed down by the first sheet pressing member. Therefore, it is possible to avoid false detection by the full-stack detection sensor due to bulging of the trailing edge of the folded sheet, and ensure the stacking capacity of the folded sheets on the sheet discharge tray. Furthermore, by pressing down the vicinity of the trailing edge of the folded sheet, it is possible to prevent the folded sheet from slipping under the sheet discharge section due to the trailing edge of the folded sheet blocking the sheet discharge section. As a result, it is possible to improve the stacking capacity of the folded sheets. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an image forming system including a sheet post-processing device 1 having a second sheet discharge section 6, which is an example of a sheet discharge device of the present invention, and an image forming device 200 to which the sheet post-processing device 1 is connected. [Figure 2] FIG. 1 is a side cross-sectional view schematically illustrating a configuration of a sheet post-processing device 1 equipped with a second sheet discharge section 6. [Figure 3] 3(a) and 3(b) are side views of a folded sheet S, showing a sheet S that has been Z-folded (FIG. 3(a)), folded in three (FIG. 3(b)), and folded in three (FIG. 3(c)). [Figure 4] FIG. 3 is a partial cross-sectional view showing the periphery of a sheet folding unit 100 in the sheet post-processing device 1 of FIG. 2; [Figure 5] FIG. 10 is a cross-sectional view showing the periphery of the sheet folding unit 100, illustrating an initial stage of the inward three-folding process of the sheet S. [Figure 6] FIG. 10 is a cross-sectional view showing the periphery of the sheet folding unit 100, illustrating the final stage of the inward three-folding process of the sheet S. [Figure 7] FIG. 10 is a cross-sectional view showing the periphery of the sheet folding unit 100, illustrating an initial stage of folding the sheet S in half. [Figure 8] A side cross-sectional view of the second sheet discharge section 6 and its surroundings of the sheet post-processing device 1. [Figure 9] 1 is a perspective view of the second sheet discharge section 6 and its surroundings seen from above; [Figure 10] FIG. 6 is a diagram showing the relationship between the size of folded sheets stacked on the second discharge tray 63 and the pressing positions of the first sheet pressing member 65 and the second sheet pressing member 67. DETAILED DESCRIPTION OF THE INVENTION

[0012]

[0023] The present invention will be described in detail below with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram showing the configuration of an image forming system including a sheet post-processing device 1 equipped with a second sheet discharge section 6, which is an example of a sheet discharge device of the present invention, and an image forming device 200 to which the sheet post-processing device 1 is connected;

[0013] As shown in FIG. 1, the image forming device 200 prints an image on a sheet (paper) based on image data input from outside via a network communication unit (not shown) or image data read by an image reading unit 201 arranged on top of the image forming device 200.

[0014] The sheet post-processing device 1 is detachably connected to the side of the image forming apparatus 200. The sheet post-processing device 1 performs post-processing such as punch hole formation, binding, and folding on sheets after images have been formed (printed) by the image forming apparatus 200. Note that the sheet post-processing device 1 is not limited to a device that performs post-processing on sheets automatically transported from the image forming apparatus 200, but may also be a device that transports sheets set by a user on a tray (not shown) to a position where the sheets can be post-processed and performs post-processing on the sheets.

[0015] Fig. 2 is a side cross-sectional view schematically showing the configuration of the sheet post-processing device 1 including the second sheet discharge section 6. As shown in Fig. 2, the sheet post-processing device 1 includes a sheet entrance 2, a first sheet transport path 3, a first sheet discharge section 4, a second sheet transport path 5, a second sheet discharge section 6, a third sheet transport path 7, a third sheet discharge section 8, a post-processing section 9, and a post-processing control section (control section) 10.

[0016] The sheet entrance 2 is an opening provided on the side of the sheet post-processing device 1 facing the image forming device 200. A sheet transported from the image forming device 200 to the sheet post-processing device 1 passes through the sheet entrance 2 and is carried into the inside of the sheet post-processing device 1.

[0017] The first sheet transport path 3 extends substantially horizontally from the sheet entrance 2 to the first sheet discharge section 4 in a direction away from the image forming apparatus 200 (to the left in FIG. 2). The direction from the sheet entrance 2 toward the first sheet discharge section 4 is referred to as the sheet transport direction in the first sheet transport path 3. The sheet entrance 2 is located at the upstream end of the first sheet transport path 3 in the sheet transport direction. The first sheet transport path 3 has multiple transport roller pairs 3r, and transports a sheet carried into the sheet post-processing device 1 from the sheet entrance 2 toward the downstream side in the sheet transport direction.

[0018] The first sheet discharge section 4 is provided on the side of the sheet post-processing device 1 opposite to the side facing the image forming device 200. The first sheet discharge section 4 is disposed at the downstream end in the sheet conveying direction of the first sheet conveying path 3. The first sheet discharge section 4 has a first discharge opening 41, a first discharge roller pair 42, and a first discharge tray 43.

[0019] The first discharge outlet 41 is located at the downstream end of the first sheet transport path 3 in the sheet transport direction. The first discharge roller pair 42 is disposed at the first discharge outlet 41. The first discharge tray 43 is located downstream of the first discharge outlet 41 in the sheet transport direction. A sheet that has been transported along the first sheet transport path 3 and reached the first discharge outlet 41 is passed through the first discharge outlet 41 by the first discharge roller pair 42 and discharged onto the first discharge tray 43. The first discharge tray 43 is one of the final discharge locations for sheets that have been post-processed by the sheet post-processing device 1. In addition, sheets that are not post-processed and small-sized sheets are also discharged to the first discharge tray 43.

[0020] The second sheet transport path 5 branches off from a first branching portion (branching portion) 31 on the first sheet transport path 3 and extends horizontally and upward in a direction away from the image forming apparatus 200 (to the left in FIG. 2 ) to the second sheet discharge portion 6. The first branching portion 31 is located downstream of the punching portion 91 in the sheet transport direction of the first sheet transport path 3. The direction from the first branching portion 31 toward the second sheet discharge portion 6 is referred to as the sheet transport direction of the second sheet transport path 5. The first branching portion 31 is located at the upstream end of the second sheet transport path 5 in the sheet transport direction. The second sheet transport path 5 has multiple transport roller pairs 5r, and branches off a sheet transported along the first sheet transport path 3 at the first branching portion 31 to transport the sheet toward the second sheet discharge portion 6.

[0021] The first branching section 31 has a first switching guide 311. The first switching guide 311 rotates between a first position (dashed line P1 in FIG. 5 ) where it guides a sheet conveyed on the first sheet conveying path 3 from the sheet entrance 2 side along the first sheet conveying path 3 to the first discharge outlet 41, and a second position (solid line P2 in FIG. 5 ) where it branches off from the first sheet conveying path 3 and guides the sheet to the second sheet conveying path 5. Furthermore, the first switching guide 311 rotates to a third position (dashed line P3 in FIG. 5 ) where it guides a sheet that has been folded and passed through a second folding conveying path 106 (described later) to the second sheet conveying path 5. The first switching guide 311 is connected to a drive mechanism (not shown), and its operation is controlled by the post-processing control section 10.

[0022] The second sheet discharge section 6 is provided above the first sheet discharge section 4 on the side of the sheet post-processing device 1 opposite to the side facing the image forming device 200. The second sheet discharge section 6 is disposed at the downstream end of the second sheet transport path 5 in the sheet transport direction. The second sheet discharge section 6 has a second discharge opening 61, a second discharge roller pair 62, and a second discharge tray 63.

[0023] The second discharge outlet 61 is located at the downstream end of the second sheet transport path 5 in the sheet transport direction. The second discharge roller pair 62 is disposed at the second discharge outlet 61. The second discharge tray 63 is located downstream of the second discharge outlet 61 in the sheet transport direction. A sheet that has been transported along the second sheet transport path 5 and reached the second discharge outlet 61 is passed through the second discharge outlet 61 by the second discharge roller pair 62 and discharged onto the second discharge tray 63. The second discharge tray 63 is one of the final discharge locations for sheets that have been post-processed by the sheet post-processing device 1.

[0024] The third sheet transport path 7 branches off from the second branching portion 32 on the first sheet transport path 3 and extends downward to the third sheet discharge portion 8. The direction from the second branching portion 32 toward the third sheet discharge portion 8 is referred to as the sheet transport direction of the third sheet transport path 7. The second branching portion 32 is located downstream of the first branching portion 31 with respect to the sheet transport direction of the first sheet transport path 3, and is located at the upstream end of the third sheet transport path 7 in the sheet transport direction. The third sheet transport path 7 has multiple transport roller pairs 7r, and causes the sheet transported along the first sheet transport path 3 to branch off at the second branching portion 32 and be transported toward the third sheet discharge portion 8.

[0025] The second branching section 32 has a second switching guide 321. The second switching guide 321 rotates between a first position (see FIG. 5 ) where the second switching guide 321 guides a sheet conveyed on the first sheet conveying path 3 from the sheet entrance 2 side to the first discharge outlet 41 along the first sheet conveying path 3, and a second position (not shown) where the second switching guide 321 guides a sheet conveyed on the first sheet conveying path 3 from the sheet entrance 2 side, passes through the second branching section 32, and is switched back to the third sheet conveying path 7. The second switching guide 321 is connected to a drive mechanism (not shown), and its operation is controlled by the post-processing control section 10.

[0026] The third sheet discharge section 8 is provided below the first sheet discharge section 4 (near the lower end of the sheet post-processing device 1) on the side of the sheet post-processing device 1 opposite to the side facing the image forming device 200. The third sheet discharge section 8 has a third discharge opening 81, a third discharge roller pair 82, and a third discharge tray 83.

[0027] The third discharge outlet 81 is located at the downstream end of the third sheet transport path 7 in the sheet transport direction. The third discharge roller pair 82 is arranged at the third discharge outlet 81. The third discharge tray 83 is located downstream of the third discharge outlet 81 in the sheet transport direction. A sheet that has been transported along the third sheet transport path 7 and reached the third discharge outlet 81 is passed through the third discharge outlet 81 by the third discharge roller pair 82 and discharged onto the third discharge tray 83. The third discharge tray 83 is one of the final discharge locations for sheets that have been post-processed by the sheet post-processing device 1.

[0028] The post-processing section 9 performs predetermined post-processing on sheets on which images have been formed by the image forming device 200 and which have been transported into the sheet post-processing device 1. The post-processing section 9 includes a punching section 91, a stapling section 92, a sheet folding unit 100, and a binding section 94.

[0029] The punching unit 91 is disposed on the first sheet transport path 3, immediately downstream of the sheet entrance 2. The punching unit 91 performs a punching process on the sheet transported on the first sheet transport path 3, to form punch holes.

[0030] The staple unit 92 is disposed immediately upstream of the first sheet discharge unit 4 in the sheet conveying direction of the first sheet conveying path 3. The staple unit 92 staples (binds) a sheet bundle formed by stacking a plurality of sheets, and binds the sheet bundle.

[0031] The sheet folding unit 100 is disposed downstream of the punching section 91 and upstream of the stapling section 92 in the sheet conveying direction of the first sheet conveying path 3. In other words, the sheet folding unit 100 is located upstream of the first branching section 31 in the sheet conveying direction of the first sheet conveying path 3. The sheet folding unit 100 folds a single sheet to form a crease.

[0032] The sheet folding unit 100 can fold a single sheet in two, Z-fold, outward three-fold, inward three-fold, etc. The detailed configuration of the sheet folding unit 100 will be described later.

[0033] 3(a) to 3(c) are side views of a sheet S that has been Z-folded, folded outward in three, and folded inward in three, respectively.

[0034] 3(a), for example, Z-folding is a folding method in which the downstream side of the sheet S in the sheet conveying direction of the first sheet conveying path 3 is formed into a Z shape when viewed from the sheet width direction perpendicular to the sheet conveying direction. In Z-folding, a downstream portion Sd of the sheet S downstream of the first fold F1 in the first sheet conveying path 3 and an upstream portion Su upstream of the second fold F2 face each other in the vertical direction, separated by a middle portion Sc between the two folds. In the sheet conveying direction, the lengths of the downstream portion Sd and the middle portion Sc of the sheet S are approximately the same and are shorter than the length of the upstream portion Su.

[0035] Folding in three outwards is a folding method in which the entire sheet S is folded into a Z-shape when viewed in the sheet width direction, as shown in Fig. 3(b), for example. In folding in three outwards, a downstream portion Sd of the sheet S downstream of the first fold F1 in the first sheet conveying path 3 and an upstream portion Su of the sheet S upstream of the second fold F2 face each other in the vertical direction, separated by a middle portion Sc between the two folds. In the sheet conveying direction, the lengths of the downstream portion Sd, middle portion Sc, and upstream portion Su of the sheet S are approximately the same.

[0036] In the inner tri-fold, as shown in Figure 3(c), for example, an upstream portion Su of the sheet S, which is upstream of the first fold F1, and a downstream portion Sd, which is downstream of the second fold F2, in the sheet conveying direction of the first sheet conveying path 3, come into surface contact facing each other in the vertical direction on one side (the upper side in Figure 3(c)) of the plane of the intermediate portion Sc between the two folds.

[0037] The binding section 94 is disposed immediately upstream of the third sheet discharge section 8 in the sheet conveying direction of the third sheet conveying path 7. The binding section 94 has a center folding section 941 and a saddle stitching section 942. The binding section 94 performs center folding and saddle stitching on a sheet bundle formed by stacking a plurality of sheets, in which the sheets are folded and stitched at approximately the center in the sheet conveying direction, to form a booklet.

[0038] The post-processing control unit 10 includes a CPU, a memory unit, and other electronic circuits and electronic components (none of which are shown). The post-processing control unit 10 is communicably connected to the main body control unit of the image forming apparatus 200 (see FIG. 1). The post-processing control unit 10 receives commands from the main body control unit and, using the CPU, controls the operation of each component provided in the sheet post-processing device 1 based on control programs and data stored in the memory unit to perform processing related to the functions of the sheet post-processing device 1. The first sheet transport path 3, the first sheet discharge unit 4, the second sheet transport path 5, the second sheet discharge unit 6, the third sheet transport path 7, the third sheet discharge unit 8, and the post-processing unit 9 each receive individual commands from the post-processing control unit 10 and perform post-processing on sheets in cooperation with each other. The functions of the post-processing control unit (control unit) 10 may also be performed by the main body control unit of the image forming apparatus 200.

[0039] Next, the configuration of sheet folding unit 100 will be described with reference to Figures 4 and 5. Figure 4 is a partial cross-sectional view showing the periphery of sheet folding unit 100 in sheet post-processing device 1 of Figure 2. Figure 5 is a cross-sectional view showing the periphery of sheet folding unit 100 of Figure 4. Sheet folding unit 100 includes a first folding section 101, a first folding conveying path 102, a first folding roller pair 103, a first folding guide 104, a second folding section 105, a second folding conveying path 106, a second folding roller pair 107, and a second folding guide 108.

[0040] Further, conveying roller pairs 3r are arranged at two locations in the sheet folding unit 100 along the first sheet conveying path 3. Hereinafter, of the conveying roller pairs 3r arranged at two locations in the sheet folding unit 100, the upstream conveying roller pair 3r consisting of the second roller 112 and the conveying roller 114 will be referred to as the first assist roller pair 3r1, and the downstream conveying roller pair 3r will be referred to as the second assist roller pair 3r2.

[0041] The first folding unit 101 is disposed on the first sheet conveying path 3. Specifically, the first folding unit 101 is located downstream of the perforation unit 91 (see FIG. 2 ) and upstream of the first branch unit 31 in the sheet conveying direction on the first sheet conveying path 3.

[0042] The first folding conveying path 102 branches off from the first folding section 101 on the first sheet conveying path 3 and extends downward. In this embodiment, the first folding conveying path 102 extends downward substantially vertically from the first folding section 101. The lower end of the first folding conveying path 102 connects to the third sheet conveying path 7.

[0043] First folding roller pair 103 is disposed on first folding conveying path 102 in first folding section 101. First folding roller pair 103 is composed of a first roller 111 disposed on one side of first folding conveying path 102 and a second roller 112 disposed on the other side. First folding roller pair 103 forms first folding nip N1 when one of first roller 111 and second roller 112 is biased toward the other and comes into contact with the other. A sheet that enters first folding conveying path 102 passes through first folding nip N1 and is conveyed toward the lower side of first folding roller pair 103.

[0044] The second roller 112, together with the transport roller 114, constitutes a first assist roller pair 3r1.

[0045] First folding guide 104 is disposed opposite first folding nip portion N1 in first folding section 101. More specifically, first folding guide 104 is disposed upstream of first folding nip portion N1 in the sheet conveying direction of first folding conveying path 102 (upper side in FIG. 4). When a sheet is not to be folded, first folding guide 104 retracts in a direction away from first folding nip portion N1 relative to first sheet conveying path 3, that is, above first sheet conveying path 3 in FIG. 4. This prevents a sheet passing through first sheet conveying path 3 from coming into contact with first folding guide 104.

[0046] The first folding guide 104 is connected to a guide drive mechanism (not shown) and is capable of reciprocating movement toward and away from the first folding nip N1. The first folding guide 104 guides the sheet conveyed on the first sheet conveying path 3 to the first folding nip N1.

[0047] The second folding unit 105 is disposed on the first folding conveying path 102. Specifically, the second folding unit 105 is located downstream of the first folding roller pair 103 in the sheet conveying direction of the first folding conveying path 102 and below the first folding nip portion N1.

[0048] The second folding conveying path 106 branches off and extends from the second folding unit 105 on the first folding conveying path 102. The second folding conveying path 106 extends from the second folding unit 105 toward the side (left side in FIG. 4) of the sheet post-processing device 1 where the first sheet discharge unit 4 is provided. In other words, the second folding conveying path 106 extends in approximately the same direction as the extension direction of the first sheet conveying path 3.

[0049] The first sheet conveying path 3 includes a junction 33 located downstream in the sheet conveying direction from the first branching portion 31. The second folding conveying path 106 merges with the first sheet conveying path 3 at the junction 33. In other words, the junction 33 is located downstream in the sheet conveying direction of the first sheet conveying path 3 from the first branching portion 31, and the sheets that have been folded in the sheet folding unit 100 merge with the junction 33.

[0050] In this embodiment, the junction 33 is located near the first switching guide 311. The first switching guide 311 is switchable among a first position P1, a second position P2, and a third position P3 (see FIG. 5 for all of these). The first switching guide 311 located at the first position P1 guides a sheet conveyed on the first sheet conveying path 3 from the sheet entrance 2 side to the first discharge outlet 41. The first switching guide 311 located at the second position P2 guides a sheet conveyed on the first sheet conveying path 3 to the second sheet conveying path 5. The first switching guide 311 located at the third position P3 guides a folded sheet conveyed on the second folding conveying path 106 to the second discharge outlet 61 via the second sheet conveying path 5.

[0051] Second folding roller pair 107 is disposed on second folding conveying path 106 in second folding section 105. Second folding roller pair 107 is composed of a first roller 111 disposed on one side of second folding conveying path 105 and a third roller 113 disposed on the other side. Second folding roller pair 107 forms second folding nip portion N2 when one of first roller 111 and third roller 113 is biased toward the other and comes into contact with the other. The sheet that has entered second folding conveying path 106 passes through second folding nip portion N2 and is conveyed toward junction 33 (the left side of second folding roller pair 107 in FIG. 4).

[0052] Second folding guide 108 is disposed opposite second folding nip portion N2 in second folding section 105. More specifically, second folding guide 108 is disposed upstream of second folding nip portion N2 in the sheet conveying direction of second folding conveying path 106 (to the right in FIG. 4). When a sheet is not to be folded, second folding guide 108 retreats in a direction away from second folding nip portion N2 relative to first folding conveying path 102, that is, to the right of first folding conveying path 102 in FIG. 4. This prevents a sheet passing through first folding conveying path 102 from coming into contact with second folding guide 108.

[0053] The second folding guide 108 is connected to a drive mechanism (not shown) and is capable of reciprocating movement in a direction toward and away from the second folding nip portion N2. The second folding guide 108 guides the sheet conveyed on the first folding conveying path 102 to the second folding nip portion N2.

[0054] Next, the operation of the sheet folding unit 100 will be described with reference to Figures 5 and 6. As an example of the operation of the sheet folding unit 100, an inner three-fold process in which a sheet is folded into three as shown in Figure 3(c) will be described. Figures 5 and 6 are cross-sectional views showing the periphery of the sheet folding unit 100 in Figure 4, and show the initial and final stages of the inner three-fold process of the sheet S.

[0055] 5, the sheet S carried into the first sheet conveying path 3 from the sheet entrance 2 (see FIG. 2) has its downstream portion in the sheet conveying direction guided from the first branching section 31 to the second sheet conveying path 5. The first switching guide 311 of the first branching section 31 is located at a second position P2 where the sheet S, being conveyed on the first sheet conveying path 3 from the sheet entrance 2 side, is guided to the second sheet conveying path 5.

[0056] In the first folding section 101, the first folding guide 104 is positioned in a direction away from the first folding nip section N1 than the first sheet conveying path 3, i.e., in Figure 5, in a position (retracted position) that is retracted above the first sheet conveying path 3.

[0057] When the portion of the sheet S corresponding to the first fold F1 (see Figure 3(c)) reaches the first folding section 101, the rotation of the second assist roller pair 3r2, the first assist roller pair 3r1, and each conveying roller pair 5r of the second sheet conveying path 5 is stopped, and the conveying of the sheet S is stopped.

[0058] With the first assist roller pair 3r1 stopped, the second assist roller pair 3r2 and each conveyance roller pair 5r of the second sheet conveyance path 5 are rotated in the reverse direction, so that the portion of the sheet S downstream of the first assist roller pair 3r1 moves upstream (to the right in FIG. 5), causing the sheet S to bend in the first folding portion 101. After that, the first folding guide 104 starts moving from the retracted position in a direction approaching the first folding nip portion N1.

[0059] The second assist roller pair 3r2 is further rotated in the reverse direction, and the first folding guide 104 is moved to a position (folding position) where it contacts the first folding nip N1 via the sheet S. As the first folding guide 104 moves from the retracted position to the folding position, the bent portion of the sheet S is guided into the first folding nip N1. By moving the first folding guide 104 to the folding position after forming a bend in the sheet S in this way, an excessive load from the first folding guide 104 is not applied to the sheet S, and it is possible to prevent the sheet S from wrinkling or breaking. A first fold F1 is formed in the sheet S that has passed through the first folding nip N1.

[0060] The timing for forming the first fold F1 in the sheet S is determined based on the timing at which a sheet detection sensor (not shown) detects the downstream end of the sheet S in the sheet conveying direction in the first sheet conveying path 3, the overall length of the sheet S in the sheet conveying direction, and the conveying speed of the sheet S. The same applies to the timing for forming the second fold F2, which will be described later.

[0061] In second folding section 105, second folding guide 108 is retracted in a direction away from second folding nip N2 relative to first folding conveying path 102 (to the right of first folding conveying path 102 in FIG. 5).

[0062] The sheet S that has passed through the first folding nip portion N1 is conveyed in a direction (downward) away from the first folding roller pair 103 along the first folding conveying path 102, with the first fold F1 at the front and two regions extending along the sheet conveying direction overlapping each other. The upstream portion of the sheet S that has passed through the first folding conveying path 102 in the conveying direction temporarily enters the third sheet conveying path 7.

[0063] When the portion of the sheet S corresponding to the second fold F2 (see Figure 3(c)) reaches the second folding section 105, the rotation of the second assist roller pair 3r2, the first assist roller pair 3r1, each conveying roller pair 5r of the second sheet conveying path 5, the first folding roller pair 103, and each conveying roller pair 7r of the third sheet conveying path 7 is stopped, and the conveyance of the sheet S is stopped.

[0064] After the conveyance of the sheet S is stopped, each conveyance roller pair 7r of the third sheet conveyance path 7 is rotated in the reverse direction, so that the portion of the sheet S downstream of the second folding section 105 in the sheet conveyance direction (below the second folding section 105 in Figure 5) moves upstream (upper side in Figure 5), causing the sheet S to bend at the second folding section 105.

[0065] Next, second folding guide 108 moves in a direction approaching second folding nip portion N2 and comes into contact with sheet S. As second folding guide 108 comes into contact, the bent portion of sheet S is guided into second folding nip portion N2 of second folding roller pair 107. Then, a second fold F2 is formed in sheet S that has passed through second folding nip portion N2 (see FIG. 6).

[0066] 6, sheet S that has passed through second folding nip portion N2 is conveyed along second folding conveying path 106 in a direction away from second folding roller pair 107, with three overlapping regions extending along the sheet conveying direction, starting from second fold F2. The upstream portion of sheet S in the conveying direction that has passed through second folding conveying path 106 enters junction 33. At this time, in junction 33, first switching guide 311 disposed at third position P3 guides sheet S to second sheet conveying path 5, passes through second discharge port 61, and is discharged to second sheet discharge portion 6 (see FIG. 2).

[0067] When folding the sheet S in the sheet folding unit 100, the post-processing control unit 10 guides the downstream portion of the sheet S, which has been carried into the first sheet conveying path 3 from the sheet entrance 2, from the first branching section 31 to the second sheet conveying path 5, and then reverses the conveying direction of the sheet S and guides the sheet S to the sheet folding unit 100, where the sheet S is folded. Furthermore, the post-processing control unit 10 causes the folded sheet S to merge with the second sheet conveying path 5 at the merging section 33.

[0068] The above has explained the process of folding the sheet S inward in three. However, the Z-folding process in which the sheet S is folded in the Z direction as shown in FIG. 3(a) and the outward tri-folding process in which the sheet S is folded outward in three as shown in FIG. 3(b) can also be performed in exactly the same manner using the procedures shown in FIGS. 5 and 6 by changing the timing of forming the first fold F1 and the second fold F2 in the sheet S.

[0069] FIG. 7 is a cross-sectional view showing the periphery of sheet folding unit 100, illustrating the initial stage of folding a sheet S in half. When folding a sheet S in half, the sheet S is conveyed into sheet folding unit 100 with first folding guide 104 positioned at the folding position. As a result, the leading edge of the sheet S is guided along first folding guide 104 and second roller 112 to first folding nip N1. Next, the sheet S is stopped at a position where the center of the sheet S faces second folding nip N2 of second folding roller pair 107. In this state, second folding guide 108 is moved toward second folding nip N2 to contact the sheet S, thereby guiding the center of the sheet S to second folding nip N2 of second folding roller pair 107. As a result, a crease is formed in the sheet S that has passed through second folding nip N2, and the sheet S is folded in half. The folded sheet S is guided to the second sheet conveying path 5 by the first switching guide 311 arranged at the third position P3, passes through the second discharge port 61 and is discharged to the second sheet discharge section 6 (see Figure 2).

[0070] Fig. 8 is a side cross-sectional view of the periphery of the second sheet discharge section 6 of the sheet post-processing device 1. Fig. 9 is a perspective view of the periphery of the second sheet discharge section 6 seen from above. The second sheet discharge section 6 includes a second discharge roller pair 62, a second discharge tray 63, a first sheet pressing member 65, and a second sheet pressing member 67.

[0071] The second discharge tray 63 has a tray upper surface 63a on which sheets (hereinafter referred to as folded sheets) that have been folded in the sheet folding unit 100 and discharged from the second discharge outlet 61 are stacked, and a rear wall portion 63b that rises from the upstream end of the tray upper surface 63a in the discharge direction.

[0072] One end (base end) of the first sheet pressing member 65 is fixed above the pair of discharge rollers 62, and the other end (tip end 65a) extends to below the pair of second discharge rollers 62. The first sheet pressing member 65 comes into contact with the folded sheets discharged from the second discharge opening 61, and presses the folded sheets stacked on the tray upper surface 63a of the second discharge tray 63 from the upstream end to the vicinity of the center in the discharge direction.

[0073] The first sheet pressing member 65 is a sheet-like member that can be elastically deformed. The first sheet pressing member 65 flexes and deforms depending on the number of folded sheets stacked on the tray upper surface 63a, thereby changing the position that presses down on the folded sheets. The first sheet pressing member 65 can be made of a material such as a polyethylene terephthalate (PET) film having a thickness of 0.2 to 0.3 mm, for example.

[0074] First sheet pressing member 65 may be configured as a plate-like member that can swing in the sheet discharge direction (from right to left in FIG. 8) under its own weight. In this case, first sheet pressing member 65 swings in accordance with the number of folded sheets stacked on tray upper surface 63a, thereby changing the position where the folded sheets are pressed.

[0075] The second sheet pressing member 67 presses down the fold portion to the center portion downstream in the discharge direction of the folded sheets discharged and stacked on the tray upper surface 63a of the second discharge tray 63. The second sheet pressing member 67 is swingably supported on a rotation fulcrum 67a provided downstream in the discharge direction from the first sheet pressing member 65. The second sheet pressing member 67 swings downstream (clockwise in FIG. 8) or upstream (counterclockwise in FIG. 8) in the sheet discharge direction depending on the number of folded sheets stacked on the tray upper surface 63a, thereby pressing down the fold portion and the vicinity of the center of the folded sheets stacked on the tray upper surface 63a without blocking the discharge of the folded sheets from the second discharge opening 61 to the second discharge tray 63.

[0076] The first sheet pressing member 65 and the second sheet pressing member 67 are held by a holding member 68. The holding member 68 is detachable from the second sheet discharge section 6. The first sheet pressing member 65 and the second sheet pressing member 67 are detachable from the second sheet discharge section 6 together with the holding member 68.

[0077] The second sheet discharge section 6 is equipped with a full-state detection sensor 69. The full-state detection sensor 69 is disposed inside the rear wall surface 63a of the second discharge tray 63 (upstream side in the discharge direction), in the vicinity directly below the second discharge roller pair 62, and detects a full state of the folded sheets stacked on the tray upper surface 63a. The full-state detection sensor 69 has a detection region R (see FIG. 10) with a predetermined width in the height direction at a detection position in the width direction perpendicular to the discharge direction.

[0078] Full detection sensor 69 is a reflective photointerrupter (PI) sensor equipped with a detection unit having a light-emitting unit and a light-receiving unit. When the number of folded sheets stacked on tray upper surface 63a reaches a certain number (e.g., 30 sheets), the stack surface (upper surface) of the folded sheets falls within detection area R of full detection sensor 69. In this state, the detection unit of full detection sensor 69 becomes able to detect light reflected from the folded sheets, and detects that tray upper surface 63a is full of folded sheets.

[0079] 10 is a diagram showing the relationship between the size of folded sheets stacked on tray upper surface 63a and the pressing positions of first sheet pressing member 65 and second sheet pressing member 67. In this embodiment, five types of folded sheets S1 to S5 are discharged from second discharge opening 61 onto second discharge tray 63 and stacked thereon.

[0080] Folded sheet S1 is an A4R-sized sheet folded in three (see Figure 3(c)). The size L1 of folded sheet S1 in the ejection direction is 102 mm. Folded sheet S2 is an A3-sized sheet folded in three. The size L2 of folded sheet S2 in the ejection direction is 140 mm.

[0081] Folded sheet S3 is an A4-sized sheet that has been Z-folded (see Figure 3(a)). The size L3 of folded sheet S3 in the ejection direction is 148.5 mm. Folded sheet S4 is an A3-sized sheet that has been Z-folded. The size L4 of folded sheet S4 in the ejection direction is 210 mm. Folded sheet S5 is a 13-inch sheet that has been folded in half. The size L5 of folded sheet S5 in the ejection direction is 241.3 mm.

[0082] The first sheet pressing member 65 secures the stacking capacity of folded sheets on the second discharge tray 63 by pressing down the rear end of the folded sheet that falls within the detection area R of the full-load detection sensor 69. The first sheet pressing member 65 presses down any position within the range from the center of the smallest-sized folded sheet S1 stacked on the tray upper surface 63a of the second discharge tray 63 in the discharge direction to the rear wall surface 63a (within a range of 50 mm from the rear wall surface 63a). The first sheet pressing member 65 also presses down any bulging of the folded sheet S1 at a pressing position where the leading end 65a protrudes below the lower limit of the detection area R (inside the triangle in FIG. 10) of the full-load detection sensor 69. When the number of folded sheets S1 to S5 stacked on the tray upper surface 63a exceeds a predetermined number, the first sheet pressing member 65 retreats from the pressing position to allow the stacking surface of the folded sheets S1 to S5 to rise.

[0083] This allows the first sheet pressing member 65 to reliably press down on the vicinity of the rear ends of the folded sheets S1, S2, which bulge more at the rear ends. This prevents the full-stack detection sensor 69 from erroneously detecting the bulge at the rear ends of the folded sheets S1, S2, and ensures a sufficient stacking capacity of the folded sheets S1, S2 on the second discharge tray 63. Furthermore, by pressing down on the vicinity of the rear ends of the folded sheets S1 to S5, the occurrence of the folded sheets slipping under the second discharge outlet 61 due to the rear ends of the folded sheets S1 to S5 blocking the second discharge outlet 61 is suppressed. As a result, the stacking capacity of the folded sheets S1 to S5 can be improved.

[0084] Note that the collision load with the first sheet pressing member 65 may cause curling or jamming of the folded sheets S1 to S5 discharged from the second discharge opening 61. Therefore, it is preferable to set the collision angle θ1 between the first sheet pressing member 65 and the folded sheets S1 to S5 discharged from the second discharge opening 61 to 85° or less when no external force is applied to the first sheet pressing member 65.

[0085] The second sheet pressing member 67 presses down on the creases at the leading edges of the folded sheets S1 to S5 stacked on the tray upper surface 63a, thereby ensuring the capacity of the tray upper surface 63a for the folded sheets S1 to S5. The leading edge 67b of the second sheet pressing member 67 presses down on any position within the range from the center, in the discharge direction, of the largest-sized folded sheet S5 stacked on the tray upper surface 63a to the crease at the leading edge, in the discharge direction, of the smallest-sized folded sheet S1 (within a range of 100 to 140 mm from the rear wall surface 63a). The second sheet pressing member 67 also presses down on the bulging of the folded sheets S1 to S5 at a pressing position where the leading edge 67a protrudes below the lower limit of the detection area R of the full-sheet detection sensor 69. When the number of stacked folded sheets S1 to S5 exceeds a predetermined number, the second sheet pressing member 67 retreats from the pressing position to allow the stacking surface of the folded sheets S1 to S5 to rise.

[0086] This allows the second sheet pressing member 67 to reliably press down on the folds of the Z-folded folded sheets S3 and S4, which bulge more at the leading edge. This prevents the full-stack detection sensor 69 from erroneously detecting the bulge at the leading edge of the folded sheets S3 and S4, and ensures a sufficient stack of folded sheets S3 to S5 on the second discharge tray 63. Furthermore, by pressing down on the center to leading edge of the folded sheets S1 to S5 in the discharge direction that have already been loaded on the second discharge tray 63, pushing out of the sheets by the subsequent folded sheets S1 to S5 is suppressed, thereby improving the alignment of the folded sheets S1 to S5 in the discharge direction and width direction.

[0087] If the second sheet pressing member 67 is positioned so that its tip 67b presses the creases of the folded sheets S3 and S4, the tip 67b of the second sheet pressing member 67 cannot press the crease at the leading edge of the smallest folded sheet S1. Therefore, the underside of the second sheet pressing member 67 is formed with an inclined surface 67c that slopes from the tip 67b toward the tray upper surface 63a. This allows the inclined surface 67c of the second sheet pressing member 67 to come into contact with the crease at the leading edge of the folded sheet S1 when multiple folded sheets S1 are stacked on the tray upper surface 63a. As a result, bulging at the leading edge of the folded sheet S1 can be suppressed.

[0088] Note that the collision load with the second sheet pressing member 67 may cause curling or jamming of the folded sheets discharged from the second discharge outlet 61. Therefore, it is preferable to set the collision angle θ2 between the second sheet pressing member 67 and the folded sheets S1 to S5 discharged from the second discharge outlet 61 to 40° or less when the tip end 67b of the second sheet pressing member 67 is in contact with the second discharge tray 63 (the position indicated by the broken line in FIG. 10).

[0089] Although the embodiments of the present invention have been described above, the scope of the present invention is not limited thereto, and various modifications are possible without departing from the spirit of the invention. For example, in the above embodiment, an example has been shown in which sheet folding unit 100 includes first folding roller pair 103 and second folding roller pair 107, each of which is composed of three rollers, first roller 111 to third roller 113. However, the present invention is not limited thereto, and sheet folding unit 100 may be configured to include only first folding roller pair 103, which is composed of first roller 111 and second roller 112.

[0090] Furthermore, in the above embodiment, the sheet that has been folded by the sheet folding unit 100 is discharged to the second sheet discharge section 6, but the sheet that has been folded may also be discharged to the first sheet discharge section 4. In that case, the first sheet pressing member 65 and the second sheet pressing member 67 may be disposed in the first sheet discharge section 4.

[0091] In the above embodiment, the second sheet discharge section 6 of the sheet post-processing device 1 equipped with the sheet folding unit 100 that folds sheets has been exemplified as the sheet discharge device of the present invention, but the present invention is not limited to this. For example, the present invention may be similarly applied to a sheet discharge section of a sheet post-processing device 1 that does not have the sheet folding unit 100 and into which folded sheets that have been folded by a separate sheet folding device are transported. [Industrial Applicability]

[0092] The present invention can be used in a sheet discharge device that discharges a sheet that has been subjected to a folding process to form a crease in the sheet, and a sheet post-processing device that includes a sheet discharge device. [Explanation of symbols]

[0093] 1 Sheet post-processing device 2 Sheet entrance 3 First sheet transport path 3r Transport roller pair 3r1 First assist roller vs. 3r2 2nd Assist Roller vs. 4 First sheet discharge section 5 Second sheet transport path 6 Second sheet discharge section (sheet discharge device) 61 2nd outlet 62 Second discharge roller pair (discharge roller pair) 63 Second output tray (sheet output tray) 63a Tray top 63b Rear wall 65 First sheet retaining member 67 Second sheet retaining member 68 Retaining member 69 Full detection sensor 10 Post-processing control unit 100 Sheet Folding Unit S seat S1~S5 Folded sheets

Claims

1. a sheet discharge unit having a pair of discharge rollers for discharging the folded sheet; a sheet discharge tray having a tray upper surface on which the folded sheets discharged from the sheet discharge section are stacked, and a rear wall portion rising from an end portion of the tray upper surface on an upstream side in a discharge direction; a fullness detection sensor provided in the sheet discharge section, which detects the height of a stacking surface of the folded sheets stacked on the upper surface of the tray, thereby detecting whether the sheet discharge tray is full of the folded sheets stacked on the tray; a first sheet pressing member that comes into contact with the folded sheet discharged from the sheet discharge portion and presses a rear end side in a discharge direction of the folded sheet stacked on the upper surface of the tray; a second sheet pressing member that presses the leading end side of the folded sheets stacked on the upper surface of the tray in a discharge direction; Equipped with the fullness detection sensor has a detection area having a predetermined width in a height direction at a detection position in a width direction perpendicular to the discharge direction, the first sheet pressing member is positioned outside the detection position in the width direction, and at a pressing position extending from above the pair of discharge rollers to below the lower limit of the detection area, contacts any position within a range from the center in the discharge direction of the smallest size folded sheet stacked on the upper surface of the tray to the rear wall portion to press down on the bulge of the folded sheet, and when the number of folded sheets stacked exceeds a predetermined number, retreats from the pressing position to allow the stacking surface of the folded sheets to rise.

2. 2. The sheet discharge device according to claim 1, wherein a collision angle between the first sheet pressure member and the folded sheet discharged from the sheet discharge section is 85° or less when no external force is applied to the first sheet pressure member.

3. 3. The sheet discharge device according to claim 1, wherein the second sheet pressing member, at a pressing position extending below a lower limit of the detection area, contacts any position within a range from the center in the discharge direction of the largest folded sheet stacked on the sheet stacking surface to the fold portion in the discharge direction of the smallest folded sheet to press down on the bulge of the folded sheet, and when the number of stacked folded sheets exceeds a predetermined number, retracts from the pressing position to allow the stacking surface for the folded sheets to rise.

4. the second sheet pressing member contacts the folded sheet discharged from the sheet discharge portion downstream of the first sheet pressing member in the discharge direction, 4. The sheet discharge device according to claim 3, wherein when the tip of the second sheet pressing member is in contact with the upper surface of the tray, the collision angle between the second sheet pressing member and the folded sheet discharged from the sheet discharge section is 40° or less.

5. 5. The sheet ejection device according to claim 1, wherein the first sheet pressing member is a sheet-like member that is elastically deformable.

6. 6. The sheet discharging device according to claim 1, wherein the second sheet pressing member is a plate-like member that is swingable along the sheet discharging direction.

7. 7. The sheet discharging device according to claim 1, wherein the first sheet pressing member and the second sheet pressing member are held by a single holding member, and the holding member is detachable from the sheet discharging section.

8. a folding unit that performs a predetermined folding process on the sheet; the sheet ejection device according to any one of claims 1 to 7, which is provided downstream of the folding unit in a sheet conveying direction; A sheet post-processing device comprising:

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