Sheet processing device

Abstract

To provide a sheet processing apparatus which can strengthen the addition of folds.SOLUTION: A sheet processing apparatus has a folding unit, a first roller and a pair of second rollers. The folding unit folds a sheet to form a fold. The pair of second rollers sandwich the sheet between the first roller and the second rollers and move in a fold direction to add more folds. The pair of second rollers are aligned in the fold direction. The first roller has a first large diameter part and a first small diameter part. The first large diameter part is in a first position in a conveyance direction. The first small diameter part is in a second position in the conveyance direction. A diameter of the first small diameter part is smaller than that of the first large diameter part. Each second roller has a second large diameter part and a second small diameter part. The second large diameter part is in the second position. The second small diameter part sandwiches the sheet between the first small dimeter part and the second large diameter part. The second small diameter part is in the first position. The second small diameter part sandwiches the sheet between the first large diameter part and the second small diameter part. A diameter of the second small diameter part is smaller than that of the second large diameter part.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] Embodiments of the present invention relate to a sheet processing apparatus.

Background Art

[0002] A sheet processing apparatus includes a folding unit that folds a sheet to form a crease, and a doubling unit that doubles the crease of the sheet. There is a need for a sheet processing apparatus that can strengthen the doubling.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a sheet processing apparatus that can strengthen the doubling.

Means for Solving the Problems

[0005] A sheet processing apparatus according to the first embodiment includes a folding unit, a first roller, and a pair of second rollers. The folding unit folds the sheet to form a crease. The first roller is rotatable about an axis along the conveying direction perpendicular to the crease direction. The first roller moves along the crease direction. The pair of second rollers are rotatable about an axis along the conveying direction. The pair of second rollers move along the crease direction with the sheet sandwiched between them and the first roller to deepen the crease. The pair of second rollers are aligned in the crease direction. The first roller has a first large diameter section and a first small diameter section. The first large diameter section is in a first position in the conveying direction. The first small diameter section is in a second position in the conveying direction. The first small diameter section is smaller in diameter than the first large diameter section. Each of the pair of second rollers has a second large diameter section and a second small diameter section. The second large diameter section is in a second position. The second large-diameter section has a sheet sandwiched between it and the first small-diameter section. The second small-diameter section is in the first position. The second small-diameter section has a sheet sandwiched between it and the first large-diameter section. The second small-diameter section has a smaller diameter than the second large-diameter section.

[0006] The sheet processing apparatus according to the second embodiment is the sheet processing apparatus according to the first embodiment, wherein the outer diameter of the first roller at the third position in the conveying direction is greater than the distance between the pair of second rollers at the third position.

[0007] The sheet processing apparatus according to the third embodiment is a sheet processing apparatus according to the first embodiment or the second embodiment, wherein the outer diameter of the first large-diameter portion is greater than the distance between the pair of second rollers at the second position.

[0008] The sheet processing apparatus according to the fourth embodiment is a sheet processing apparatus according to any of the first to third embodiments described above, wherein the rotation axis of the first roller is located at an intermediate position between the rotation axes of a pair of second rollers in the folding direction.

[0009] The sheet processing apparatus according to the fifth embodiment is a sheet processing apparatus according to any of the first to third embodiments described above, wherein the rotation axis of the first roller is located in a position shifted in the folding direction with respect to the midpoint of the rotation axes of a pair of second rollers in the folding direction. [Brief explanation of the drawing]

[0010] [Figure 1] Schematic diagram of an image forming apparatus. [Figure 2] A block diagram showing an example of the functional configuration of an image forming apparatus. [Figure 3] A front view showing a schematic configuration of the saddle folding mechanism in the sheet processing apparatus of the first embodiment. [Figure 4] A perspective view of the folding unit in the sheet processing apparatus of the first embodiment. [Figure 5] A front cross-sectional view showing the schematic configuration of the folding unit and the additional folding unit in the sheet processing apparatus of the first embodiment. [Figure 6] A perspective view of the roller unit in the sheet processing device of the first embodiment. [Figure 7] A side view showing the first roller and a pair of second rollers of the first embodiment. [Figure 8] A front view showing the first and second rollers of the first embodiment. [Figure 9] A diagram showing the YZ cross-section at the third position of the first roller and a pair of second rollers in the first embodiment. [Figure 10] A diagram illustrating the operation of the folding unit according to the first embodiment. [Figure 11] A front view showing how the first and second rollers of the first embodiment grip the sheet. [Figure 12] A side view showing the first roller and a pair of second rollers of the second embodiment. [Figure 13] A diagram illustrating the operation of the folding unit of the second embodiment. [Figure 14] A front view showing the first and second rollers of the third embodiment. [Modes for carrying out the invention]

[0011] Hereinafter, the sheet processing apparatus according to the embodiment will be described with reference to the drawings. In the following description, components having the same or similar functions are denoted by the same reference numerals, and redundant descriptions of those components may be omitted.

[0012] FIG. 1 is a schematic configuration diagram of an image forming apparatus 1. For example, the image forming apparatus 1 is arranged in a workplace. The image forming apparatus 1 includes an image forming apparatus main body 100 and a sheet processing apparatus 200. The image forming apparatus main body 100 and the sheet processing apparatus 200 are arranged adjacent to each other.

[0013] The image forming apparatus main body 100 will be described. The image forming apparatus main body 100 forms an image on a sheet P (recording medium) using a recording agent. The sheet P is, for example, plain paper or label paper. A specific example of the recording agent is toner. The toner is either a toner used as a color erasable recording agent or a toner used as a non-color erasable recording agent.

[0014] For example, the image forming apparatus main body 100 is a multifunction device. As shown in FIG. 1, the image forming apparatus main body 100 includes a display unit 15, an operation unit 14, an image reading unit 16, a printer unit 17, a sheet storage unit 18, a paper discharge roller 19, and a first control unit 80.

[0015] The display unit 15 is an image display device such as a liquid crystal display or an organic EL (Electro Luminescence) display. The display unit 15 displays various information regarding the image forming apparatus main body 100 and the sheet processing apparatus 200. The operation unit 14 has a plurality of buttons. The operation unit 14 receives a user's operation. The operation unit 14 outputs a signal corresponding to the operation performed by the user to the first control unit 80 of the image forming apparatus main body 100. The display unit 15 and the operation unit 14 may be configured as an integrated touch panel.

[0016] The image reading unit 16 reads image information of a reading target as light brightness and darkness. The image reading unit 16 outputs the read image information to the printer unit 17. The sheet storage section 18 stores the sheet P used for image formation. The sheet storage section 18 supplies the stored sheet P to the printer section 17.

[0017] The printer unit 17 forms an image on the sheet based on image information generated by the image reading unit 16 or image information received via the communication channel. The printer unit 17 includes an image forming unit, a transfer unit, and a fixing device. The image forming unit forms an electrostatic latent image on the photoreceptor drum based on the image information. The image forming unit forms a visible image by attaching toner to the electrostatic latent image. The transfer unit transfers the visible image onto the sheet. The fixing device heats and pressurizes the toner to fix the visible image onto the sheet. The paper discharge roller 19 is positioned near the paper discharge opening of the image forming apparatus body 100. The paper discharge roller 19 feeds the sheet P on which the image has been formed to the sheet processing apparatus 200.

[0018] Figure 2 is a block diagram showing an example of the functional configuration of the image forming apparatus 1. As shown in Figure 2, the image forming apparatus main unit 100 includes a CPU (Central Processing Unit) 81, memory 82, auxiliary storage device 83, etc., connected by a bus, and executes a program. The image forming apparatus main unit 100 functions as a device comprising a display unit 15, an operation unit 14, an image reading unit 16, a printer unit 17, a sheet storage unit 18, and a communication unit 84, depending on the execution of the program.

[0019] The CPU 81 functions as the first control unit 80 by executing programs stored in the memory 82 and the auxiliary storage device 83. The first control unit 80 controls the operation of each part of the image forming apparatus body 100 and the sheet processing device 200. The auxiliary storage device 83 is configured using storage devices such as magnetic hard disk drives and semiconductor storage devices. The auxiliary storage device 83 stores information. The communication unit 84 is configured to include a communication interface for connecting its own device to an external device. The communication unit 84 communicates with the external device via the communication interface.

[0020] The sheet processing device 200 will now be described. As shown in Figure 1, the sheet processing apparatus 200 performs post-processing on the image-formed sheet P. For example, post-processing may be stapling or saddle folding. The sheet processing apparatus 200 includes a stapling mechanism 20, a saddle folding mechanism 30, and a second control unit (control unit) 90.

[0021] The stapling mechanism 20 includes a waiting tray 21, a processing tray 22, and a stapler 23. The stapler 23 applies stapling to the peripheral edges of multiple sheets P. Hereinafter, multiple sheets P will be referred to as a sheet bundle. The stapled sheets P are conveyed by a conveyor belt 24 and discharged onto a movable tray 27.

[0022] The sheet processing device 200 includes a movable tray 27, an upper tray 26, and a lower tray 28. Stapled sheets P are discharged into the movable tray 27. Unstapled sheets P are discharged into the upper tray 26. The lower tray 28 is located at the bottom of the sheet processing device 200. Sheets P processed by the saddle folding mechanism 30 are discharged into the lower tray 28.

[0023] (First Embodiment) Figure 3 is a front view showing a schematic configuration of the saddle folding mechanism 30 in the sheet processing apparatus 200 of the first embodiment. As shown in Figure 3, the saddle folding mechanism 30 includes a sheet support section 31 and a post-processing section 40. The post-processing section 40 includes a staple section 41, a folding unit 42, and an additional folding unit 45.

[0024] The sheet support section 31 is located at the downstream end of the sheet P in the conveying direction of the sheet P in the conveying path. Sheets P are stacked on the sheet support section 31. The sheet support section 31 includes a bed 32 and a stacker 35. The bed 32 has a stacking surface 33 that supports the surface of the sheet P.

[0025] The X, Y, and Z directions of the Cartesian coordinate system are defined as follows for the local coordinate system of the saddle folding mechanism 30. The X direction is the normal direction to the stacking surface 33 of the bed 32. The +X direction is the direction in which the sheet P is placed on the bed 32. The +X direction is inclined upward from the horizontal direction. The Z direction is the transport direction of the sheet P in the saddle folding mechanism 30. The -Z direction is the direction in which the sheet P moves toward the sheet support section 31 through the transport path. The -Z direction is inclined downward from the horizontal direction. The Y direction is the horizontal direction.

[0026] The bed 32 is roughly plate-shaped and can place sheets P on a stacking surface 33 facing the +X direction. The bed 32 is located on both sides in the Z direction, flanking the folding unit 42. The sheets P placed on the stacking surface 33 are supported by a stacker 35. The stacker 35 restricts the leading edge in the -Z direction of the sheets P that have been transported to the sheet support section 31. The stacker 35 is movable along the Z direction. For example, the stacker 35 is driven by a moving mechanism located in the -X direction of the bed 32.

[0027] The stapling section 41 processes the sheet P at a position in the +Z direction relative to the position where the sheet P is supported by the stacker 35. The stapling section 41 is located in the +Z direction of the folding unit 42. The stapling section 41 applies stapling to a predetermined position on the sheet P. For example, the predetermined position on the sheet P is the center of the sheet P in the Z direction.

[0028] The folding unit 42 processes the sheet P at a position in the +Z direction relative to the position where the sheet P is supported by the stacker 35. The folding unit 42 folds the center of the sheet P in the Z direction to create a crease F in the sheet P. The folding unit 42 has a pair of folding rollers 44 and a blade 43.

[0029] A pair of folding rollers 44 are located in the +X direction of the bed 32. The pair of folding rollers 44 are aligned in the Z direction. The axis of rotation of the pair of folding rollers 44 extends in the Y direction. The pair of folding rollers 44 are drive rollers, however, one of the pair of folding rollers 44 may be a driven roller. Each of the pair of folding rollers 44 is displaceable in the Z direction. The pair of folding rollers 44 are displaceable in the Z direction so that they can move closer to and further apart from each other. The Z-direction displacement of the pair of folding rollers 44 is linked to each other. The pair of folding rollers 44 are in contact with each other to form a nip N.

[0030] The blade 43 is flat and parallel to the XY plane. The blade 43 is tapered towards the +X direction. The blade 43 is movable in the X direction through the bed 32. The blade 43 works in cooperation with a pair of folding rollers 44 to press the sheet P into the nip N, thereby forming a fold in the sheet P that extends in the Y direction.

[0031] The fold-enhancing unit 45 is located in the +X direction of a pair of folding rollers 44. The fold-enhancing unit 45 enlarges the fold F of the sheet P.

[0032] For example, the saddle folding mechanism 30 can perform a binding process on a sheet bundle. The binding process involves stapling and saddle folding on the sheet bundle stacked in the sheet support section 31.

[0033] In the bookbinding process, the sheet stack is first stapled. The stacker 35 moves the sheet stack in the +Z direction so that the center of the sheet stack in the Z direction aligns with the position of the stapler 41. The stapler 41 staples the sheet stack.

[0034] Next, the stapled sheet bundle is subjected to a saddle fold. The stacker 35 moves the sheet bundle in the -Z direction so that the center of the sheet bundle in the Z direction aligns with the position of the blade 43. The blade 43 moves in the +X direction, pushing the center of the sheet bundle between the pair of folding rollers 44. The sheet bundle is saddle folded at its center in the Z direction. A crease F extending in the Y direction is formed on the +X edge of the saddle-folded sheet bundle. The fold-up unit 45 folds the crease F of the sheet bundle further. This completes the binding process of the sheet bundle. The bound sheet bundle is discharged into the lower tray 28.

[0035] The saddle folding mechanism 30 can perform saddle folding on one or more sheets P stacked in the sheet support section 31 without stapling, as an alternative to the bookbinding process. One or more sheets P can be a single sheet P or a bundle of sheets. In this case, the stacker 35 directly transports one or more sheets P from the stacking position to the folding unit 42. Then, in the same manner as saddle folding in the bookbinding process, folds are formed on one or more sheets P together. The folded sheets P are then discharged into the lower tray 28.

[0036] As shown in Figure 2, the sheet processing device 200 includes a CPU (Central Processing Unit) 91, memory 92, auxiliary storage device 93, etc., connected by a bus, and executes a program. Through program execution, the sheet processing device 200 functions as a device equipped with a stapling mechanism 20, a saddle folding mechanism 30, and a communication unit 94.

[0037] The CPU 91 functions as a second control unit 90 by executing programs stored in the memory 92 and auxiliary storage device 93. The second control unit 90 controls the operation of each part of the sheet processing device 200. The auxiliary storage device 93 is configured using storage devices such as magnetic hard disk drives and semiconductor storage devices. The auxiliary storage device 93 stores information. The communication unit 94 is configured to include a communication interface for connecting itself to an external device. The communication unit 94 communicates with the external device via the communication interface.

[0038] Let me explain the folding unit 45. Figure 4 is a perspective view of the folding unit 45 in the sheet processing apparatus 200 of the first embodiment. Figure 5 is a front cross-sectional view showing the schematic configuration of the folding unit 42 and the folding unit 45 in the sheet processing apparatus 200 of the first embodiment. Note that the folding roller 63 is simplified in Figure 5. As shown in Figures 4 and 5, the folding unit 45 has a frame 50, a support part 55, a roller unit 60, and a drive part 70. The direction of sheet transport in the folding unit 45 is the X direction, which is perpendicular to the Y direction, which is the fold direction. In the folding unit 45, the sheet P is transported from the upstream folding unit 42 in the +X direction.

[0039] The frame 50 covers the folding unit 45 in the -X, +Z, +Y, and -Y directions. The frame 50 has a main plate in the -X direction. The main plate has a slit 51 extending in the Y direction. The slit 51 allows the saddle-folded sheet P in the folding unit 42 to enter. As shown in Figure 4, the frame 50 has a top plate in the +Z direction. The top plate has a guide hole 52 extending in the Y direction. The frame 50 has a pair of side plates in the +Y and -Y directions. The pair of side plates support both ends of a guide bar 53 extending in the Y direction. The guide hole 52 and the guide bar 53 guide the movement of the roller unit 60 in the Y direction.

[0040] As shown in Figure 5, the support portion 55 includes a first support plate 56, a second support plate 57, a first film 58, and a second film 59. The first support plate 56 and the second support plate 57 are parallel to the XY plane.

[0041] The first support plate 56 is located at the +Z end of the slit 51. The first support plate 56 is movable in the Z direction. The first support plate 56 supports the sheet P from the +Z direction. The second support plate 57 is located in the -Z direction relative to the first support plate 56. The second support plate 57 is fixed to the frame 50. The second support plate 57 presses the sheet P from the -Z direction to the +Z direction.

[0042] The first film 58 and the second film 59 are formed in a film shape from a resin material or the like and are flexible. The first film 58 and the second film 59 extend in the Y direction. The first film 58 is fixed to the +X end of the first support plate 56. The first film 58 extends from the first support plate 56 in the +X direction. The first film 58 is movable in the Z direction together with the first support plate 56. The first film 58 covers the fold F of the sheet P from the +Z direction. The second film 59 is fixed to the +X end of the second support plate 57. The second film 59 extends from the second support plate 57 in the +X direction. The second film 59 covers the fold F of the sheet P from the -Z direction.

[0043] Figure 6 is a perspective view of the roller unit 60 in the sheet processing apparatus 200 of the first embodiment. As shown in Figure 6, the roller unit 60 has a roller frame 61 and a folding roller 63. The roller frame 61 is formed in a roughly C-shape when viewed from the Y direction and has an opening 62 in the -X direction. The opening 62 prevents interference between the sheet P that enters the folding unit 45 and the roller unit 60.

[0044] The folding roller 63 has a first roller 64 and a pair of second rollers 65. The rotation axes of the first roller 64 and the second rollers 65 each extend in the X direction.

[0045] The first roller 64 is positioned in the +Z direction of the opening 62 and inside the roller frame 61. The first roller 64 is supported by an arm member 66 in a rotatable manner. The arm member 66 is supported by the roller frame 61 in a manner that allows it to rotate around a pivot axis 67. A coil spring 68 is attached to the arm member 66. A pair of second rollers 65 are positioned in the -Z direction of the opening 62 and inside the roller frame 61. The pair of second rollers 65 are rotatably supported by the roller frame 61.

[0046] Figure 7 is a side view showing the first roller 64 and a pair of second rollers 65 of the first embodiment. As shown in Figure 7, the pair of second rollers 65 are arranged side by side in the Y direction such that their respective axes of rotation overlap when viewed from the Y direction. The pair of second rollers 65 are spaced apart in the Y direction. The axis of rotation of the first roller 64 lies between the axes of rotation of the pair of second rollers 65 in the Y direction. The axis of rotation of the first roller 64 lies at position C, which is midway between the axes of rotation of the pair of second rollers 65 in the Y direction.

[0047] Figure 8 is a front view showing the first roller 64 and the second roller 65 of the first embodiment. As shown in Figure 8, the first roller 64 includes a first large-diameter portion 641 at a first position A in the X direction, a first small-diameter portion 642 at a second position B in the X direction, and a first tapered portion 643 located between the first large-diameter portion 641 and the first small-diameter portion 642. The second position B is a different position from the first position A and is located in the -X direction from the first position A. Note that the first position A and the second position B shown in Figure 8 are examples.

[0048] The first large-diameter portion 641 has a first outer diameter, extends in the X direction, and has an outer circumferential surface that can contact the sheet P. The first small-diameter portion 642 is located in the -X direction, further than the first large-diameter portion 641. The first small-diameter portion 642 is spaced apart from the first large-diameter portion 641 in the X direction. The first small-diameter portion 642 has a smaller diameter than the second large-diameter portion 651. The first small-diameter portion 642 has a second outer diameter, extends in the X direction, and has an outer circumferential surface that can contact the sheet P. In the illustrated example, the sizes of the first large-diameter portion 641 and the first small-diameter portion 642 in the X direction are the same. The first tapered portion 643 is formed in the shape of a frustocone. The outer diameter of the first tapered portion 643 gradually decreases along the X direction toward the first small-diameter portion 642. The first tapered portion 643 has an outer surface that connects to the outer surfaces of the first large diameter portion 641 and the first small diameter portion 642, respectively.

[0049] The pair of second rollers 65 are formed to be the same shape and size as each other. Each second roller 65 includes a second large diameter portion 651 at a second position B in the X direction, a second small diameter portion 652 at a first position A in the X direction, and a second tapered portion 653 located between the second large diameter portion 651 and the second small diameter portion 652.

[0050] The second large-diameter portion 651 extends in the X direction with a third outer diameter and has an outer circumferential surface that can contact the sheet P. In this embodiment, the third outer diameter is equal to the first outer diameter. The formation range of the second large-diameter portion 651 in the X direction coincides with the formation range of the first small-diameter portion 642 in the X direction. The second small-diameter portion 652 is located in the +X direction more than the second large-diameter portion 651. The second small-diameter portion 652 is positioned at a distance from the second large-diameter portion 651 in the X direction. The second small-diameter portion 652 has a smaller diameter than the first large-diameter portion 641. The first small-diameter portion 642 extends in the X direction with a fourth outer diameter and has an outer circumferential surface that can contact the sheet P. In this embodiment, the fourth outer diameter is equal to the second outer diameter. The formation range of the second small-diameter portion 652 in the X direction coincides with the formation range of the first large-diameter portion 641 in the X direction. The difference between the third outer diameter and the fourth outer diameter is the same as the difference between the first outer diameter and the second outer diameter. In the illustrated example, the sizes of the second large diameter portion 651 and the second small diameter portion 652 in the X direction are the same. The second tapered portion 653 is located in the same position as the first tapered portion 643 in the X direction. The second tapered portion 653 is formed in the shape of a frustocone. The outer diameter of the second tapered portion 653 gradually increases along the X direction toward the second large diameter portion 651. The second tapered portion 653 has an outer surface that connects to the outer surfaces of the second large diameter portion 651 and the second small diameter portion 652, respectively. The formation range of the second tapered portion 653 in the X direction is the same as the formation range of the first tapered portion 643 in the X direction.

[0051] The first tapered portion 643 and the second tapered portion 653 are formed so that their opposing portions are parallel to each other. The inclination angle of the outer surface of the first tapered portion 643 with respect to the rotation axis of the first roller 64 is the same as the inclination angle of the outer surface of the second tapered portion 653 with respect to the rotation axis of the second roller 65. In this embodiment, the outer surfaces of the first roller 64 and the second roller 65 are formed to be the same shape and size as each other.

[0052] Figure 9 shows a YZ cross-section of the first roller and the pair of second rollers at a third position in the first embodiment. Note that the third position shown in Figure 9 coincides with the second position B shown in Figure 8. However, the third position shown in Figure 9 is just an example. As shown in Figure 9, the outer diameter of the first roller 64 is larger than the distance between the pair of second rollers 65. Specifically, the outer diameter of the first roller 64 at the third position in the X direction is larger than the distance G between the pair of second rollers 65 at the third position in the X direction. The third position is all positions in the X direction range from the opposite edge of the first small diameter portion 642 on the first large diameter portion 641 to the opposite edge of the first large diameter portion 641 on the first small diameter portion 642. Because the outer diameter of the first roller 64 is larger than the distance between the pair of second rollers 65, it cannot pass between the pair of second rollers 65 in the Y direction. Because the outer diameter of the first roller 64 is larger than the distance between the pair of second rollers 65 in the Y direction at all positions in the X direction, the outer diameter of the first large-diameter portion 641 is larger than the distance between the pair of second rollers 65 at the second position B. In other words, the outer diameter of the first large-diameter portion 641 is larger than the distance between the pair of second large-diameter portions 651.

[0053] As shown in Figure 8, the first roller 64 and the second roller 65 are displaceable relative to each other in the Z direction, allowing them to move closer to and further apart from each other. In this embodiment, the first roller 64 is stationary in the Z direction. The first roller 64 and each of the second rollers 65 contact each other via the first film 58 and the second film 59 to form a nip. The first roller 64 contacts the sheet P from the +Z direction via the first film 58. The pair of second rollers 65 contact the sheet P from the -Z direction, opposite to the first roller 64, via the second film 59. The second large diameter portion 651 sandwiches the sheet P between itself and the first small diameter portion 642. The second small diameter portion 652 sandwiches the sheet P between itself and the first large diameter portion 641. The second tapered portion 653 sandwiches the sheet P between itself and the first tapered portion 643. The pair of second rollers 65 evenly press the first roller 64 through the sheet P. The first roller 64 and each of the second rollers 65 move along the Y direction, sandwiching the fold F of the sheet P between them. By rolling on the sheet P, the first roller 64 and the second rollers 65 press and reinforce the fold F.

[0054] As shown in Figure 4, the drive unit 70 is located in the -Z direction of the folding unit 45. The drive unit 70 includes a drive belt 72 and a motor 71. The drive belt 72 is routed between a pair of pulleys that are spaced apart in the Y direction. The axes of rotation of the pair of pulleys are parallel to the X direction. A portion of the drive belt 72 is connected to the roller unit 60. The motor 71 moves the drive belt 72 around the pulleys. This causes the roller unit 60 to move in the Y direction.

[0055] As shown in Figure 3, when the saddle folding mechanism 30 is in operation, the blade 43 pushes the center of the sheet P in the Z direction between the pair of folding rollers 44. A crease F is formed on the +X direction edge of the saddle-folded sheet P. The pair of folding rollers 44 move the sheet P in the +X direction. As shown in Figure 5, the movement of the sheet P stops when the crease F reaches between the first film 58 and the second film 59 of the folding unit 45.

[0056] The folding unit 45 of this embodiment folds the crease F of the sheet P as follows. The second control unit 90 controls the operation of each part of the folding unit 45. The second control unit 90 performs the following folding operation only when the number of sheets P to be saddle-folded is equal to or greater than a predetermined number. However, the second control unit 90 may perform the following folding operation regardless of the number of sheets P to be saddle-folded.

[0057] The first support plate 56 and the first film 58 of the support section 55 move in the -Z direction. Sheet P is sandwiched between the first support plate 56 and the first film 58 and the second support plate 57 and the second film 59. The fold F of sheet P is sandwiched between the first film 58 and the second film 59.

[0058] As shown in Figure 4, the inner -Y end of the frame 50 is the home position HP of the roller unit 60. When the saddle folding mechanism 30 is not in operation, the roller unit 60 waits in the home position HP. In the home position HP, the first roller 64 of the folding roller 63 shown in Figure 5 is separated from the second roller 65 in the +Z direction.

[0059] As the sheet P enters the folding unit 45, the roller unit 60 moves from its home position HP in the +Y direction. As the roller unit 60 moves, the coil spring 68 pulls the arm member 66 downward in the -Z direction. The first roller 64, supported by the arm member 66, moves in the -Z direction and approaches the second roller 65.

[0060] The first roller 64 contacts the surface of the first film 58 in the +Z direction. The second roller 65 contacts the surface of the second film 59 in the -Z direction. The first roller 64 and the second roller 65 grip the fold F of the sheet P through the first film 58 and the second film 59. The coil spring 68 shown in Figure 5 biases the arm member 66 in the -Z direction. The first roller 64, supported by the arm member 66, presses the fold F of the sheet P through the first film 58. The fold-up roller 63 moves in the Y direction along the fold F. As a result, the fold F of the sheet P is folded up. During the folding operation by the folding-up unit 45 described above, the sheet P is sandwiched between the pair of folding rollers 44.

[0061] Figure 10 is an explanatory diagram of the operation of the folding unit 45 of the first embodiment, and is a side view showing the folding rollers 63 that hold the sheet P. As shown in Figure 10, during the folding operation, the first roller 64 pushes the sheet P towards the space between the pair of second rollers 65. The first roller 64 and the pair of second rollers 65 move in the Y direction while holding the sheet P. When the bundle of sheets P is relatively thin, the first roller 64 and the pair of second rollers 65 hold the sheet P so that the fold F of the sheet P, which extends in the Y direction when viewed from the +X direction, bends. Note that Figure 10 shows the state before the fold F of the sheet P held between the first roller 64 and the pair of second rollers 65 bends.

[0062] Figure 11 is a front view showing how the first roller 64 and the second roller 65 of the first embodiment sandwich the sheet P. As shown in Figure 11, the portion of the sheet P sandwiched between the first roller 64 and each of the second rollers 65 flexes in a stepped manner as its position in a direction perpendicular to the X direction changes depending on its position in the X direction. The portion of the sheet P sandwiched between the first roller 64 and each of the second rollers 65 comprises a first location PA, a second location PB, and a third location PC. The first location PA is sandwiched between a first large diameter portion 641 and a second small diameter portion 652. The second location PB is sandwiched between a first small diameter portion 642 and a second large diameter portion 651. The third location PC is sandwiched between a first tapered portion 643 and a second tapered portion 653. The first location PA is located closer to the fold F of the sheet P than the second location PB. The first location PA is located below the second location PB. The second location PB extends parallel to the first location PA. The second location PB is offset from the first location PA in the thickness direction of the sheet P, perpendicular to the fold direction and the X direction. The third location PC is located between the first location PA and the second location PB. The third location PC extends in a direction inclined with respect to the first location PA and the second location PB, following the shape of the outer circumferential surfaces of the first tapered portion 643 and the second tapered portion 653. The sheet P, extending in the -X direction from the fold F, is bent in the thickness direction of the sheet P, perpendicular to the fold direction, by being sandwiched between the first roller 64 and the second roller 65. Force is applied to the first location PA and the second location PB in a direction perpendicular to the X direction, in the direction in which the first roller 64 and the second roller 65 sandwiching the sheet P are aligned. Force is applied to the third location PC in a direction inclined towards the X direction with respect to the direction in which the first roller 64 and the second roller 65 are aligned.

[0063] The folding unit 45 of this embodiment includes a first roller 64 and a pair of second rollers 65 that sandwich a sheet P between the first roller 64 and the second rollers 65. In this configuration, the first roller 64 pushes the sheet P toward the space between the pair of second rollers 65, applying force along the fold F as shown in Figure 10, causing the sheet P to flex near the fold F and thus reinforcing the fold F. However, in some cases, the first roller 64 may not be able to sufficiently push a sheet bundle with a relatively large number of sheets P toward the space between the pair of second rollers 65. In this case, the first roller 64 and the pair of second rollers 65 may not be able to flex the sheet P, and it may not be possible to apply sufficient force to the sheet P located inside the sheet bundle. As a result, it may not be possible to reinforce the fold F.

[0064] In this embodiment, the folding unit 45 further has the following configuration. The first roller 64 has a first large-diameter portion 641 at a first position A in the X direction, and a first small-diameter portion 642 at a second position B in the X direction, which has a smaller diameter than the first large-diameter portion 641. Each of the pair of second rollers 65 has a second large-diameter portion 651 at a second position B in the X direction, which sandwiches the sheet P between itself and the first small-diameter portion 642, and a second small-diameter portion 652 at a first position A in the X direction, which sandwiches the sheet P between itself and the first large-diameter portion 641, which has a smaller diameter than the second large-diameter portion 651. With this configuration, a first location PA on the sheet P sandwiched between the first large-diameter portion 641 and the second small-diameter portion 652, and a second location PB sandwiched between the first small-diameter portion 642 and the second large-diameter portion 651, are shifted in the thickness direction of the sheet P. As a result, the part of sheet P located between the first point PA and the second point PB flexes, and a force in the X direction, which is the direction of sheet P's transport and perpendicular to the fold direction, is also applied to sheet P. Therefore, not only the force along the fold F but also the force in the direction of sheet P's transport is applied to sheet P, thereby reliably strengthening the fold F.

[0065] The first roller 64 is located between the first large-diameter portion 641 and the first small-diameter portion 642, and has a first tapered portion 643 whose outer diameter gradually decreases as it moves toward the first small-diameter portion 642 along the X direction. The second roller 65 is located between the second large-diameter portion 651 and the second small-diameter portion 652, and has a second tapered portion 653 whose outer diameter gradually increases as it moves toward the second large-diameter portion 651 along the X direction. With this configuration, the sheet P is sandwiched between the first tapered portion 643 and the second tapered portion 653. A third location PC on the sheet P, located between the first location PA and the second location PB, extends along the outer circumferential surfaces of the first tapered portion 643 and the second tapered portion 653. As a result, the sheet P is sandwiched between the first roller 64 and the second roller 65 in a bent state. Therefore, a force in the X direction perpendicular to the fold direction can be reliably applied to the sheet P at the third location PC. Thus, the fold F can be reliably strengthened.

[0066] The opposing portions of the first tapered section 643 and the second tapered section 653 are parallel to each other. This configuration allows the first roller 64 and the second roller 65 to evenly grip the third point PC of the sheet P. Therefore, a force in the X direction perpendicular to the fold direction can be reliably applied to the sheet P at the third point PC. Consequently, the fold F can be reliably strengthened.

[0067] The first large-diameter portion 641 of the first roller 64 is located in the +X direction more than the first small-diameter portion 642. With this configuration, the portion of the sheet P that is pressed between the pair of second rollers 65 by the first large-diameter portion 641 is closer to the fold F than the portion that is pressed between the pair of second rollers 65 by the first small-diameter portion 642. As a result, when the sheet P is folded, the fold F is pressed between the pair of second rollers 65 by the first large-diameter portion 641, so the first roller 64 contacts a wider area of ​​the fold F compared to a configuration in which the fold F contacts the first small-diameter portion. Therefore, the force applied from the first roller 64 to the fold F can be distributed over a wider area. Also, compared to a configuration in which the fold F contacts the first small-diameter portion, the bending of the fold F with a small radius of curvature can be suppressed. Therefore, excessive force applied to the fold F during the folding operation can be suppressed.

[0068] The pair of second rollers 65 are located below the first rollers 64 and are immobile in the Z direction. This configuration prevents the second rollers 65, located below the sheet P, from moving closer to or further away from the sheet P in the Z direction relative to its movement path. As a result, the sheet P, which may sag due to gravity, can be stably moved between the first rollers 64 and the second rollers 65.

[0069] The first roller 64 is displaceable in the Z direction. The first small-diameter portion 642 of the first roller 64 is located in the -X direction more than the first large-diameter portion 641 of the first roller 64. With this configuration, when the sheet P is pushed in the Z direction by the first roller 64 approaching the second roller 65, the portion of the sheet P pushed by the second large-diameter portion 651 is displaced more in the Z direction than the portion of the sheet P pushed by the first small-diameter portion 642. The portion of the sheet P pushed by the second large-diameter portion 651 is near the fold F, which is the downstream end of the sheet P in the transport direction. Therefore, it is possible to suppress the large displacement of the upstream portion of the sheet P in the transport direction, which is away from the fold F, by the first roller 64. Consequently, it is possible to suppress the sheet P from being pushed and shifted by the first roller 64, which is displaced in the Z direction, during the folding operation.

[0070] The outer diameter of the first roller 64 at a third position in the X direction is greater than the distance between each second roller 65 at a third position in the X direction. With this configuration, the first roller 64 cannot pass between the pair of second rollers 65 in the Y direction. Therefore, the sheet P pressed by the first roller 64 between the pair of second rollers 65 will not get stuck between the pair of second rollers 65, and damage such as wrinkles and indentations to the sheet P can be suppressed.

[0071] The outer diameter of the first large-diameter portion 641 is greater than the distance between the pair of second rollers 65 at the second position B. With this configuration, it is possible to prevent the sheet P from being pulled by the first large-diameter portion 641 at the first position A and from excessively digging into the space between the second rollers 65 at the second position B. Therefore, it is possible to prevent damage such as wrinkles from occurring in the sheet P.

[0072] The rotation axis of the first roller 64 is located at position C, which is midway between the rotation axes of the pair of second rollers 65 in the X direction. With this configuration, the first roller 64 can apply force evenly to each of the second rollers 65 on the sheet P sandwiched between the first roller 64 and the pair of second rollers 65. This suppresses damage such as wrinkles to the sheet P.

[0073] In this embodiment, the outer diameter of the first roller 64 is greater than the distance between the pair of second rollers 65 at all positions in the X direction. However, the configuration is not limited to this. The outer diameter of the first roller 64 only needs to be greater than the distance between the pair of second rollers 65 at at least one location in the X direction. In other words, the third position may be any position in the X direction range from the opposite edge of the first small diameter portion 642 on the first large diameter portion 641 to the opposite edge of the first large diameter portion 641 on the first small diameter portion 642. This makes it possible to prevent the first roller 64 from passing between the pair of second rollers 65 in the Y direction.

[0074] (Second embodiment) A second embodiment will be described with reference to Figures 12 and 13. Figure 12 is a side view showing the first roller 64 and a pair of second rollers 65 in the second embodiment. In the second embodiment shown in Figure 12, the position of the first roller 64 relative to the pair of second rollers 65 is different from that of the first embodiment. Other than what is described below, the configuration is the same as in the first embodiment.

[0075] As shown in Figure 12, the rotation axis of the first roller 64 lies between the rotation axes of the pair of second rollers 65 in the Y direction. The rotation axis of the first roller 64 is offset in the Y direction from the midpoint C of the rotation axes of the pair of second rollers 65. The rotation axis of the first roller 64 is offset in the -Y direction from the midpoint C of the rotation axes of the pair of second rollers 65. In this embodiment, the -Y direction is closer to the home position HP.

[0076] Figure 13 is an explanatory diagram of the operation of the folding unit 145 of the second embodiment. As shown in Figure 13, during the folding operation, the first roller 64 pushes the sheet P between the pair of second rollers 65. The first roller 64 and the pair of second rollers 65 clamp the sheet P so that the fold F of the sheet P extending in the Y direction when viewed from the +X direction is flexed. The first roller 64 pushes the sheet P in a direction inclined toward the rotation axis of each second roller 65 with respect to the -Z direction. Each second roller 65 pushes the sheet P in a direction inclined toward the rotation axis of the first roller 64 with respect to the +Z direction. The first roller 64 and the pair of second rollers 65 move in the Y direction while clamping the sheet P so that the fold F of the sheet P extending in the Y direction when viewed from the +X direction is flexed.

[0077] This embodiment provides the same effects as the first embodiment. In addition, in this embodiment, the first roller 64 is positioned closer to the -Y direction with respect to the intermediate position C of the pair of second rollers 65. As a result, the distance between the first roller 64 and the second roller 65 in the +Y direction is wider than the distance between the first roller 64 and the second roller 65 in the -Y direction. Therefore, when the folding roller 63 moves from the home position HP in the +Y direction, the sheet P can easily enter between the first roller 64 and the second roller 65 from the +Y direction. Thus, a smooth folding operation by the folding unit 145 can be achieved.

[0078] (Third embodiment) A third embodiment will be described with reference to Figure 14. Figure 14 is a front view showing the first roller 64 and the second roller 65 of the third embodiment. In the third embodiment shown in Figure 14, the positional relationship between the first large-diameter portion 641 and the first small-diameter portion 642 in the first roller 64, and the positional relationship between the second large-diameter portion 651 and the second small-diameter portion 652 in the second roller 65 differs from that of the first embodiment. Other than what is described below, the configuration is the same as in the first embodiment.

[0079] As shown in Figure 14, the first roller 64 comprises a first large-diameter portion 641 at a first position A in the X direction, a first small-diameter portion 642 at a second position B in the X direction, and a first tapered portion 643 located between the first large-diameter portion 641 and the first small-diameter portion 642. The second position B is a different position from the first position A and is located in the +X direction from the first position A. Each second roller 65 comprises a second large-diameter portion 651 at the second position B in the X direction, a second small-diameter portion 652 at the first position A in the X direction, and a second tapered portion 653 located between the second large-diameter portion 651 and the second small-diameter portion 652. With this configuration, this embodiment achieves the same effects as the first embodiment.

[0080] In the above embodiment, each of the folding rollers 63 has a tapered portion, but the configuration is not limited to this. That is, the folding rollers may not have a tapered portion and may have a configuration in which a large diameter portion and a small diameter portion are adjacent to each other.

[0081] In the above embodiment, the folding roller has a large-diameter portion and a small-diameter portion extending with a constant outer diameter, but it is not limited to this configuration. For example, the folding roller may be formed in a frustoconical shape along its entire axial length and have different outer diameters at two different points in the axial direction.

[0082] In the above embodiment, the second roller 65 is immovable in the Z direction. However, the second roller may also be movable in the Z direction. Alternatively, the first roller may be immovable in the Z direction, while the pair of second rollers are movable in the Z direction.

[0083] According to at least one embodiment described above, the first roller 64 has a first large-diameter portion 641 at a first position A in the X direction and a first small-diameter portion 642 at a second position B in the X direction, which has a smaller diameter than the first large-diameter portion 641. Each of the pair of second rollers 65 has a second large-diameter portion 651 at a second position B in the X direction, which sandwiches the sheet P between itself and the first small-diameter portion 642, and a second small-diameter portion 652 at a first position A in the X direction, which sandwiches the sheet P between itself and the first large-diameter portion 641, which has a smaller diameter than the second large-diameter portion 651. With this configuration, not only the force along the fold F but also the force in the conveying direction of the sheet P can be applied to the sheet P, thereby reliably strengthening the fold F.

[0084] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents.

[0085] The invention described in the specification and drawings of this application is listed below. (Note 1) A folding unit that bends the sheet to form a crease, A first roller is provided so as to be rotatable about an axis along the conveying direction perpendicular to the folding direction, and moves along the folding direction, A pair of second rollers, arranged in the direction of the fold, are provided so as to be rotatable about an axis along the conveying direction, and move along the direction of the fold with the sheet sandwiched between them and the first roller to further fold the fold, Equipped with, The first roller has a first large-diameter portion at a first position in the conveying direction, and a first small-diameter portion at a second position in the conveying direction, which has a smaller diameter than the first large-diameter portion. Each of the pair of second rollers has a second large diameter portion located in the second position, which sandwiches the sheet between itself and the first small diameter portion, and a second small diameter portion located in the first position, which sandwiches the sheet between itself and the first large diameter portion, and which has a smaller diameter than the second large diameter portion. Sheet processing device. (Note 2) The first roller is located between the first large diameter portion and the first small diameter portion, and has a first tapered portion whose outer diameter gradually decreases as it moves toward the first small diameter portion along the conveying direction. Each of the pair of second rollers has a second tapered portion located between the second large diameter portion and the second small diameter portion, the outer diameter of which gradually increases as it moves toward the second large diameter portion along the conveying direction. The sheet processing device described in Appendix 1. (Note 3) The opposing portions of the first tapered portion and the second tapered portion are parallel to each other. The sheet processing apparatus described in Appendix 2. (Note 4) The first large-diameter portion is located downstream of the first small-diameter portion in the conveying direction. A sheet processing device as described in any one of the appendices 1 to 3. (Note 5) Either the first roller or the pair of second rollers is positioned below the other and is immovable in a direction perpendicular to the conveying direction and the folding direction. A sheet processing device as described in any one of the appendices 1 to 4. (Note 6) Either the first roller or the pair of second rollers is displaceable in a direction perpendicular to the conveying direction and the folding direction. The small diameter portion of the first small diameter portion and the second small diameter portion is located upstream in the conveying direction from the large diameter portion of the first large diameter portion and the second large diameter portion. A sheet processing device as described in any one of the appendices 1 through 6. [Explanation of Symbols]

[0086] 42...Folding unit, 64...First roller, 65...Second roller, 200...Sheet processing device, 641...First large diameter section, 642...First small diameter section, 643...First tapered section, 651...Second large diameter section, 652...Second small diameter section, 653...Second tapered section, A...First position, B...Second position, C...Intermediate position, F...Fold, P...Sheet

Claims

1. A folding unit that bends the sheet to form a crease, A first roller is provided so as to be rotatable about an axis along the conveying direction perpendicular to the folding direction, and moves along the folding direction, A pair of second rollers, arranged in the direction of the fold, are provided so as to be rotatable about an axis along the conveying direction, and move along the direction of the fold with the sheet sandwiched between them and the first roller to further fold the fold, Equipped with, The first roller has a first large-diameter portion at a first position in the conveying direction, and a first small-diameter portion at a second position in the conveying direction, which has a smaller diameter than the first large-diameter portion. Each of the pair of second rollers has a second large diameter portion located in the second position, which sandwiches the sheet between itself and the first small diameter portion, and a second small diameter portion located in the first position, which sandwiches the sheet between itself and the first large diameter portion, and which has a smaller diameter than the second large diameter portion. Sheet processing device.

2. The outer diameter of the first roller at the third position in the conveying direction is greater than the distance between the pair of second rollers at the third position. The sheet processing apparatus according to claim 1.

3. The outer diameter of the first large-diameter portion is greater than the distance between the pair of second rollers at the second position. A sheet processing apparatus according to claim 1 or claim 2.

4. The rotation axis of the first roller is located midway between the rotation axes of the pair of second rollers in the direction of the fold. A sheet processing apparatus according to claim 1 or claim 2.

5. The first roller and the pair of second rollers move toward the first side along the direction of the fold, gripping the fold and increasing the fold, The rotation axis of the first roller is located at a position shifted to the second side opposite to the first side in the folding direction, relative to the midpoint of the rotation axes of the pair of second rollers in the folding direction. A sheet processing apparatus according to claim 1 or claim 2.

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