Sheet folding device, post-processing device, image forming device, and image forming system

Abstract

To provide a sheet folding device capable of applying folds obtained by various folding ways to a sheet.SOLUTION: A sheet folding device comprises: a conveyance roller pair; a first folding roller; a second folding roller for forming a first nip with the first folding roller; a third folding roller for forming a second nip with the first folding roller; a guide member switchable to a first posture of guiding a sheet to the first nip, or a second posture of guiding the sheet to the second nip; and a controller for controlling the conveyance roller pair. The controller makes conveying speed of the first folding roller be faster than conveying speed of the conveyance roller pair in a state where the sheet is folded by the first nip or the second nip, by switching the guide member from the first posture to the second posture in a state of nipping the sheet with the first nip, or by switching the guide member from the second posture to the first posture in a state of nipping the sheet with the second nip.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a sheet folding device, a post-processing device, an image forming device, and an image forming system. [Background technology]

[0002] Patent Document 1 discloses a sheet folding device that folds and stacks sheets by switching the rotation of rollers that transport the sheets, and then discharges the stacked sheets.

[0003] Patent Document 2 discloses an apparatus that creases a sheet in one direction and discharges the sheet, allowing a user to fold the discharged sheet along the crease to form a booklet. Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 has a problem in that there is a limit to the number of sheets that can be folded at one time, and Patent Document 2 has a problem in that it is not possible to impart creases in various folding patterns.

[0005] An object of the present invention is to provide a sheet folding device that can impart creases to sheets in various folding ways. [Means for solving the problem]

[0006] In order to solve the above technical problem, one aspect of the present invention provides a folding roller assembly including a pair of conveying rollers that convey a sheet in a conveying direction; a first folding roller that is arranged downstream of the pair of conveying rollers in the conveying direction; a second folding roller that forms a first nip with the first folding roller and is driven by rotation of the first folding roller; a third folding roller that forms a second nip with the first folding roller and is driven by rotation of the first folding roller; and a folding roller that is arranged between the pair of conveying rollers and the first nip in the conveying direction and is switchable between a first position that guides the sheet to the first nip and a second position that guides the sheet to the second nip. The folding device is characterized in that it includes a guide member that can be moved in a different direction and a controller that controls the pair of conveying rollers, and the controller switches the guide member from the first position to the second position when the sheet is sandwiched in the first nip, and folds the sheet in the second nip, or switches the guide member from the second position to the first position when the sheet is sandwiched in the second nip, and folds the sheet in the first nip, and makes the conveying speed of the first folding roller faster than the conveying speed of the pair of conveying rollers when the sheet is folded in the first nip or the second nip. [Effects of the Invention]

[0007] According to the present invention, creases can be imparted to sheets in a variety of folding methods. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an external view of an image forming apparatus. [Figure 2] 3A and 3B are diagrams showing the internal configuration of a sheet folding unit and a sheet binding unit. [Figure 3] 5A and 5B are diagrams illustrating the configuration of the sheet folding unit when the guide plate is in a first position (A) and a second position (B). [Figure 4] 1A is a perspective view of a guide plate, and FIG. 1B is a view of the sheet folding unit as viewed from the thickness direction of the sheets on the main conveying path. [Figure 5] 10A to 10C are diagrams showing variations in folding positions. [Figure 6] FIG. 2 is a hardware configuration diagram of a sheet folding unit. [Figure 7] 10 is a flowchart of a double fold process. [Figure 8] 10A and 10B are diagrams illustrating the movement of the sheet folding unit in the double folding process. [Figure 9] 10A and 10B are diagrams showing the behavior of a sheet when the position of a guide plate is changed. [Figure 10] 10 is a flowchart of an inner triple fold process. [Figure 11] 10A and 10B are diagrams illustrating the movement of the sheet folding unit in the inner triple fold processing. [Figure 12] 10 is a flowchart of an outer three-fold process. [Figure 13] 10A and 10B are diagrams illustrating the movement of the sheet folding unit when folding outward the binding position. [Figure 14] 10A and 10B are diagrams illustrating the movement of the sheet folding unit when folding inward at the binding position. [Figure 15] 10A and 10B are diagrams illustrating the behavior of the sheet when the guide plate is switched from the first position to the second position. [Figure 16] 10A and 10B are diagrams illustrating a state of the sheet binding unit until the sheet reaches a pair of conveying rollers. [Figure 17] 10A and 10B are diagrams illustrating a state of the sheet binding unit when sheets are discharged onto a discharge tray without being bound. [Figure 18] 10A and 10B are diagrams illustrating a state of the sheet binding unit performing binding processing. [Figure 19] 18B is a view of the sheet binding unit as seen from the thickness direction of the sheets. FIG. [Figure 20] 10A and 10B are diagrams illustrating a state of the sheet binding unit when a bound sheet bundle is discharged onto a discharge tray. [Figure 21] 10A and 10B are diagrams showing another example of limiting the movable range of the guide plate. [Figure 22] FIG. 3 is a diagram showing the internal configuration of the punch hole punching unit. [Figure 23] FIG. 10 is another example of a hardware configuration diagram of an image forming apparatus. [Figure 24] FIG. 1 is an external view of an image forming system. [Figure 25] FIG. 2 is a diagram illustrating the hardware configuration of the image forming system. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Configuration of image forming apparatus 10] An image forming apparatus 10 according to the present invention will be described below with reference to the drawings. FIG. 1 is an external view of the image forming apparatus 10. The image forming apparatus 10 is an apparatus that forms an image on a sheet S (typically, paper). As shown in FIG. 1, the image forming apparatus 10 includes a housing 11 and an image forming unit 12.

[0010] The housing 11 is box-shaped and has an internal space that houses the components of the image forming apparatus 10. The housing 11 also has an internal space 13 that is accessible from outside the image forming apparatus 10. The internal space 13 is located, for example, slightly above the center of the housing 11 in the vertical direction. The internal space 13 is exposed to the outside by cutting out an outer wall of the housing 11. Furthermore, the internal space 13 can be fitted with a sheet folding unit 20 (sheet folding device), a sheet binding unit 30 (post-processing section, binding device), and a punch hole punching unit 50 (see FIG. 22), which will be described later.

[0011] The image forming unit 12 forms an image on the sheet S stored in the tray and discharges the sheet S with the image formed thereon to the sheet folding unit 20, the sheet binding unit 30, or the hole punching unit 50. The image forming unit 12 may be of an inkjet type that forms an image using ink, or may be of an electrophotographic type that forms an image using toner. The configuration of the image forming unit 12 is already well known, so a detailed description thereof will be omitted.

[0012] The sheet folding unit 20 is attached to the internal space 13 of the image forming apparatus 10 on the downstream side of the image forming unit 12 and upstream side of the sheet binding unit 30 of the conveyance path of the sheet S from the image forming unit 12 to the sheet binding unit 30 (the path indicated by the dashed arrow in FIG. 1). That is, the sheet S on which an image has been formed by the image forming unit 12 is first handed over to the sheet folding unit 20 and subjected to a crease or folding process described below, and then handed over to the sheet binding unit 30 and subjected to a binding process described below.

[0013] Furthermore, the sheet folding unit 20 is configured to be detachable from the image forming apparatus 10. When the sheet folding unit 20 is removed, the sheets S on which an image has been formed by the image forming section 12 are directly handed over to the sheet binding unit 30 for binding. Furthermore, a hole punching unit 50 is configured to be detachable at the position in the internal space 13 from which the sheet folding unit 20 was removed. When the hole punching unit 50 is attached, the sheets S on which an image has been formed by the image forming section 12 are first handed over to the hole punching unit 50 for punching, which will be described later, and then handed over to the sheet binding unit 30 for binding. Note that a unit that performs any processing on the sheets S, not limited to a hole punching unit, can be attached at the position in the internal space 13 from which the sheet folding unit 20 was removed.

[0014] [Configuration of the sheet folding unit 20] Fig. 2 is a diagram showing the internal configuration of the sheet folding unit 20 and the sheet binding unit 30. Fig. 3 is a diagram showing the configuration of the sheet folding unit 20 when the guide plate 26 is in the first position (A) and the second position (B). Fig. 4 is a perspective view (A) of the guide plate 26 and a diagram (B) of the sheet folding unit 20 seen from the thickness direction of the sheets S on the main transport path Ph1.

[0015] The sheet folding unit 20 and the sheet binding unit 30 are each formed as a unit, and input / output interfaces for sheets S can be connected to them. That is, the input interface IN of the sheet folding unit 20 is configured to be connectable to the output interface of the image forming unit 12. Furthermore, the input interface of the sheet binding unit 30 is configured to be connectable to the output interface of the image forming unit 12 and the output interface OUT of the sheet folding unit 20.

[0016] The sheet folding unit 20 has a function of performing a folding process to fold the sheet S, on which an image has been formed by the image forming unit 12, into a predetermined shape (for example, a Z-fold, an outward tri-fold, or a double fold), and a function of performing a crease process to provide creases in various ways. As shown in FIG. 2, the sheet folding unit 20 includes a housing 21, a pair of conveying rollers 22, a first folding roller 23, a second folding roller 24, a third folding roller 25, a guide plate 26 (guide member), a first stopper 27a and a second stopper 27b, a first sensor 28a, a second sensor 28b, and a third sensor 28c (hereinafter, these may be collectively referred to as "sheet sensors 28a, 28b, 28c"), and a drive force transmission mechanism 29.

[0017] The housing 21 is box-shaped and has an internal space for accommodating the components of the sheet folding unit 20. The internal space of the housing 21 also has a main transport path Ph1 and a return transport path Ph2, which are spaces through which the sheets S pass. The main transport path Ph1 is a transport path that runs from an input interface IN connected to the image forming unit 12 to an output interface OUT connected to the sheet binding unit 30. Hereinafter, the direction on the main transport path Ph1 from the input interface IN toward the output interface OUT will be referred to as the "transport direction." The return transport path Ph2 is a circular transport path that branches off from the main transport path Ph1 at a branch point A and merges with the main transport path Ph1 at a junction point B. The junction point B is located upstream of the branch point A in the transport direction.

[0018] The conveying roller pair 22 conveys the sheet S in the conveying direction along the main conveying path Ph1. The conveying roller pair 22 is composed of a drive roller 22a and a driven roller 22b that are arranged facing each other across the main conveying path Ph1, upstream of the branching point A in the conveying direction and downstream of the merging point B in the conveying direction (i.e., between the branching point A and the merging point B). The drive roller 22a and the driven roller 22b are rotatably supported by the housing 21. The driving force of the conveying motor 22c is transmitted to the drive roller 22a, causing it to rotate forward in a direction that conveys the sheet S in the conveying direction (clockwise in FIG. 2). The driven roller 22b is arranged facing the drive roller 22a across the main conveying path Ph1, and is driven by the rotation of the drive roller 22a. Then, when the conveying motor 22c is driven with the sheet S sandwiched between the driving roller 22a and the driven roller 22b, the sheet S is conveyed in the conveying direction along the main conveying path Ph1.

[0019] The first folding roller 23 is disposed downstream in the conveying direction from the pair of conveying rollers 22. The first folding roller 23 is rotatably supported by the housing 21 at a position facing both the main conveying path Ph1 and the return conveying path Ph2. The second folding roller 24 is rotatably supported by the housing 21 at a position facing the main conveying path Ph1. The third folding roller 25 is rotatably supported by the housing 21 at a position facing the return conveying path Ph2. The first folding roller 23 and the second folding roller 24 are disposed downstream in the conveying direction from the branching portion A, facing each other across the main conveying path Ph1. The first folding roller 23 and the third folding roller 25 are disposed between the branching portion A and the merging portion B, facing each other across the return conveying path Ph2.

[0020] The first folding roller 23 rotates forward and reverse by transmitting the driving force of the folding motor 23c. The forward rotation of the first folding roller 23 is rotation in a direction (counterclockwise in FIG. 2) that conveys the sheet S on the main conveying path Ph1 in the conveying direction. The reverse rotation of the first folding roller 23 is rotation in the opposite direction to the forward rotation. The folding motor 23c is configured to be capable of forward rotation, which rotates the first folding roller 23 forward, and reverse rotation, which rotates the first folding roller 23 reversely. The second folding roller 24 and the third folding roller 25 are driven by the rotation of the first folding roller 23.

[0021] The first folding roller 23 and the second folding roller 24 form a first nip N1 that nips the sheet S on the main conveying path Ph1. The first folding roller 23 and the third folding roller 25 form a second nip N2 that nips the sheet S on the return conveying path Ph2. "Nipping" refers to holding the sheet S with enough pressure to convey the sheet S by the rotation of the pair of rollers.

[0022] Guide plate 26 is disposed between conveying roller pair 22 and first folding roller 23 on main conveying path Ph1. That is, guide plate 26 is disposed downstream in the conveying direction from conveying roller pair 22 and upstream in the conveying direction from first folding roller 23. Guide plate 26 is rotatably supported by housing 21 in the vicinity of branching portion A. Guide plate 26 is configured to be rotatable (switchable) between a first position shown in FIG. 3(A) and a second position shown in FIG. 3(B) by transmitting a driving force of guide motor 26c.

[0023] 4A, the guide plate 26 is formed with a slit 26a that allows the sheet S to pass through. The guide plate 26 switches the destination of the sheet S. The slit 26a is formed between a pair of guide surfaces 26a1, 26a2. The guide surfaces 26a1, 26a2 face each other across the main transport path Ph1 at a distance that allows the sheet S to pass through. The guide surfaces 26a1, 26a2 guide the sheet S that is transported in the transport direction on the main transport path Ph1 by the transport roller pair 22. The distance between the guide surfaces 26a1, 26a2 is set larger on the upstream side in the transport direction than on the downstream side in the transport direction.

[0024] The first position is a position of the guide plate 26 that guides the sheet S conveyed by the conveying roller pair 22 to the first nip N1 and allows the sheet S to be conveyed from the second nip N2 to the first nip N1. The second position is a position of the guide plate 26 that guides the sheet S conveyed by the conveying roller pair 22 to the second nip N2 and allows the sheet S to be conveyed from the first nip N1 to the second nip N2.

[0025] As an example, before the leading end (the downstream end in the conveying direction) of the sheet S reaches the guide plate 26, if the guide plate 26 is set to the first position and the conveying roller pair 22 and the first folding roller 23 are rotated forward, the sheet S conveyed by the conveying roller pair 22 passes through the first nip N1 through the slit 26a of the guide plate 26 in the first position (i.e., is conveyed in the conveying direction along the main conveying path Ph1).

[0026] As another example, before the leading end of the sheet S reaches the guide plate 26, if the guide plate 26 is set to the second position, the conveying roller pair 22 is rotated forward, and the first folding roller 23 is rotated reversely, the sheet S conveyed by the conveying roller pair 22 passes through the second nip N2 through the slit 26a of the guide plate 26 in the second position (i.e., enters the return conveying path Ph2 through the branching portion A).

[0027] 8(A), when the sheet S is nipped by both the conveying roller pair 22 and the first nip N1, if the first folding roller 23 is rotated in reverse while the guide plate 26 is switched from the first position to the second position, the sheet S passes through the second nip N2 with the folding position C1 at the front. In other words, when the guide plate 26 is switched from the first position to the second position and the first folding roller 23 is rotated in reverse while the sheet S is nipped by the first nip N1, the sheet S is folded at the second nip N2. As a result, the sheet S is folded inward at the folding position C1, as shown in FIG. 8(B).

[0028] 13A, in a state where the sheet S is nipped by both the pair of conveying rollers 22 and the second nip N2, when the first folding roller 23 is rotated forward while the guide plate 26 is switched from the second position to the first position, the sheet S passes through the first nip N1 with the folding position C2 at the front. That is, when the guide plate 26 is switched from the second position to the first position and the first folding roller 23 is rotated forward while the sheet S is nipped by the second nip N2, the sheet S is folded at the first nip N1. As a result, the sheet S is folded outward at the folding position C2, as shown in FIG. 13B.

[0029] FIG. 5 is a diagram showing variations in folding positions. The "folding position" is any position between the leading edge and trailing edge of the sheet S in the conveying direction (the upstream end in the conveying direction). The sheet folding unit 20 forms a crease that passes through the folding position and extends in the width direction of the sheet S, which is perpendicular to the conveying direction. An "inner fold" is a folding method in which the front surface of the sheet S on which an image has been formed by the image forming unit 12 (the upper surface facing the drive roller 22a in FIG. 2) forms a valley. An "outer fold" is a folding method in which the front surface of the sheet S forms a peak.

[0030] For example, as shown in Figure 5(A), if the sheet S is folded inward at folding position C1 in the center in the conveyance direction, a double crease can be formed in the sheet S. If the sheet S is folded inward at folding position C2 one-third of the way from the front edge and at folding position C3 one-third of the way from the rear edge, a tri-fold can be formed in the sheet S. If the sheet S is folded outward at folding position C2 and then inward at folding position C3, a tri-fold can be formed in the sheet S. If the sheet S is folded outward at folding position C1 and then inward at folding position C4 one-quarter of the way from the rear edge, a Z-fold can be formed in the sheet S.

[0031] 5(B), the folding positions of the sheets S sequentially supplied to the sheet folding unit 20 may be shifted in the conveyance direction. More specifically, when folding a bundle of sheets S into three, the spacing (first spacing) between the folding positions C2 and C3 may be narrowed toward the innermost sheets S, and the spacing (third spacing) between the folding positions C2 and C3 may be widened toward the outermost sheets S. The relationship between the folding method and folding positions of the sheets S is assumed to be stored in advance in HDD 104 (see FIG. 6). The variations in creases that can be imparted by the sheet folding unit 20 are not limited to the example shown in FIG. 5.

[0032] As shown in FIG. 3A, the first stopper 27a abuts against the guide plate 26 in the first position, preventing the guide plate 26 from rotating in the direction away from the second position (clockwise in FIG. 3A). As shown in FIG. 3B, the second stopper 27b abuts against the guide plate 26 in the second position, preventing the guide plate 26 from rotating in the direction away from the first position (counterclockwise in FIG. 3B). This allows the guide plate 26 to rotate only between the first position and the second position (in other words, between the first stopper 27a and the second stopper 27b). In other words, the first stopper 27a and the second stopper 27b restrict the rotation range of the guide plate 26.

[0033] Sheet sensors 28a, 28b, and 28c are arranged facing the main transport path Ph1 or the return transport path Ph2. Sheet sensors 28a, 28b, and 28c detect sheet S facing the installation position and output a detection signal to controller 100 (described later). More specifically, when sheet S is present in a position facing the installation position, the detection signal is output (ON), and when sheet S is not present, the output of the detection signal is stopped (OFF). Specific examples of sheet sensors 28a, 28b, and 28c are not particularly limited, but for example, reflective optical sensors can be used.

[0034] The first sensor 28a is disposed facing the main transport path Ph1, upstream of the transport roller pair 22 in the transport direction. The first sensor 28a detects the sheet S transported from the image forming unit 12 toward the transport roller pair 22. The second sensor 28b is disposed facing the main transport path Ph1, downstream of the first nip N1 in the transport direction. The second sensor 28b detects the sheet S passing through the first nip N1 and being discharged to the sheet binding unit 30. The third sensor 28c is disposed facing the return transport path Ph2, closer to the junction B than the second nip N2. The third sensor 28c detects the sheet S passing through the second nip N2 and heading toward the junction B on the return transport path Ph2.

[0035] As shown in FIG. 4B, rotation shafts 22ax, 23x, 24x, and 26x of drive roller 22a, first folding roller 23, second folding roller 24, and guide plate 26 extend in the width direction of sheet S. Rotation shafts 22ax, 23x, 24x, and 26x penetrate partition wall 21a provided inside housing 21. Although not shown in FIG. 4B, the same applies to rotation shafts 22bx and 25x of driven roller 22b and third folding roller 25. Drive force transmission mechanism 29 is disposed on the opposite side of partition wall 21a from conveyance roller pair 22, first folding roller 23, second folding roller 24, third folding roller 25, and guide plate 26.

[0036] Drive force transmission mechanism 29 transmits the drive force of conveyance motor 22c to drive roller 22a via drive gear 29a and driven gear 29b, transmits the drive force of folding motor 23c to first folding roller 23 via drive gear 29c and driven gear 29d, and transmits the drive force of guide motor 26c to guide plate 26 via drive gear 29e and driven gear 29f. In addition, torque limiter 29g is incorporated in drive gear 29e.

[0037] Conveyance motor 22c is capable of forward rotation to rotate drive roller 22a forward. Furthermore, driven roller 22b is driven in accordance with the rotation of drive roller 22a. Folding motor 23c is capable of forward rotation to rotate first folding roller 23 forward, and reverse rotation to rotate first folding roller 23 reverse. Furthermore, second folding roller 24 and third folding roller 25 are driven in accordance with the rotation of first folding roller 23. Guide motor 26c is capable of forward rotation to switch guide plate 26 from the second position to the first position, and reverse rotation to switch guide plate 26 from the first position to the second position.

[0038] Torque limiter 29g transmits the driving force of guide motor 26c to driven gear 29f (in other words, guide plate 26) when the rotational torque is less than a threshold value (i.e., guide plate 26 is separated from first stopper 27a and second stopper 27b). On the other hand, torque limiter 29g cancels (i.e., causes idling) the transmission of the driving force from guide motor 26c to driven gear 29f (in other words, guide plate 26) when the rotational torque is equal to or greater than the threshold value (i.e., guide plate 26 is in contact with first stopper 27a and second stopper 27b).

[0039] The sheet folding unit 20 includes rotary encoders 22z and 23z (see FIG. 6) that detect the number of rotations of the rollers 22a and 23. The rotary encoders 22z and 23z output pulse signals to the controller 100, the number of which corresponds to the amount of rotation of the rollers 22a and 23. That is, the controller 100 can grasp the position of the sheet S on the main conveying path Ph1 or the return conveying path Ph2 based on the detection signals output from the sheet sensors 28a, 28b, and 28c and the pulse signals output from the rotary encoders 22z and 23z. More specifically, the controller 100 grasps the position of the sheet S by counting the number of pulse signals output from the rotary encoders 22z and 23z after the sheet sensors 28a, 28b, and 28c start outputting the detection signals.

[0040] [Configuration of the sheet binding unit 30] The sheet binding unit 30 performs a binding process (post-processing) of bundling and binding a plurality of sheets S (hereinafter referred to as a "sheet stack Sb") on which images have been formed by the image forming unit 12. In this embodiment, the sheet binding unit 30 is described as an example of a post-processing unit, but specific examples of the post-processing unit (post-processing) are not limited to this. As shown in FIG. 2, the sheet binding unit 30 includes a housing 31, an output tray 32, a plurality of conveying roller pairs 33, 34, 35, and 36, an internal tray 37, a tapping roller 38, a return roller 39, end fences 40L and 40R, side fences 41L and 41R (see FIG. 19), and a binding processing unit 42.

[0041] The housing 31 is box-shaped and has an internal space for accommodating the components of the sheet binding unit 30. The internal space of the housing 31 also has a conveying path Ph3, which is a space through which the sheets S pass. The discharge tray 32 is supported on the outer surface of the housing 31. The discharge tray 32 supports the sheets S or the sheet stack Sb conveyed by the pairs of conveying rollers 33 to 36.

[0042] The conveying roller pairs 33 to 36 are arranged at a predetermined interval on the conveying path Ph3. The conveying roller pairs 33 to 36 convey the sheet S along the conveying path Ph3. The basic configuration of the conveying roller pairs 33 to 36 is the same as that of the conveying roller pair 22 of the sheet folding unit 20. However, the conveying roller pair 36 is composed of a drive roller 36a and a driven roller 36b that can move toward and away from the drive roller 36a. Furthermore, the conveying roller pair 35 may be configured to be slidable in the width direction in order to realize a sorting process in which the sheet S is shifted in the width direction and discharged onto the discharge tray 32.

[0043] The internal tray 37 temporarily supports (stacks) multiple sheets S that are transported in order on the transport path Ph3. The tapping roller 38 is supported on the front end of a rotating arm above the internal tray 37. As the rotating arm rotates, the tapping roller 38 supplies the sheet S sandwiched between the pair of transport rollers 36 to the internal tray 37. The return roller 39 rotates while coming into contact with the upper surface of the sheet S supported on the internal tray 37, thereby guiding the sheet S toward the end fences 40L and 40R.

[0044] The end fences 40L, 40R come into contact with the downstream end of the sheet S supported by the internal tray 37 in the conveyance direction, thereby aligning the position of the sheet S in the conveyance direction. The side fences 41L, 41R come into contact with both widthwise ends of the sheet S supported by the internal tray 37, thereby aligning the position of the sheet S in the width direction. The binding processing unit 42 performs a binding process to bind the sheet stack Sb supported by the internal tray 37. The binding process performed by the binding processing unit 42 may be a staple binding process in which a staple is inserted through the sheet stack Sb to bind it, or a pressure binding process in which pressure is applied to deform the sheet stack Sb to bind it. The sheet binding unit 30 may also include a staple binding processing unit that performs the staple binding process and a pressure binding processing unit that performs the pressure binding process, which are operable independently at positions spaced apart in the width direction.

[0045] Furthermore, a manual staple slit may be provided in a position of the housing 31 facing the binding processing unit 42. The user may be configured to be able to insert a sheet stack into the binding processing unit 42 through the manual staple slit and cause the binding processing unit 42 to execute the binding process by pressing a manual staple button on the operation panel 110, which will be described later.

[0046] [Controller 100 Configuration] Fig. 6 is a hardware configuration diagram of the sheet folding unit 20. As shown in Fig. 6, the sheet folding unit 20 includes a central processing unit (CPU) 101, a random access memory (RAM) 102, a read only memory (ROM) 103, a hard disk drive (HDD) 104, and an interface (I / F) 105, which are connected via a common bus 109.

[0047] The CPU 101 is a computing means and controls the overall operation of the sheet folding unit 20. The RAM 102 is a volatile storage medium that can read and write information at high speed, and is used as a work area when the CPU 101 processes information. The ROM 103 is a read-only nonvolatile storage medium that stores programs such as firmware. The HDD 104 is a nonvolatile storage medium that can read and write information and has a large storage capacity, and stores an OS (Operating System), various control programs, application programs, etc.

[0048] The sheet folding unit 20 processes a control program stored in ROM 103, an information processing program (application program) loaded from a storage medium such as HDD 104 to RAM 102, and the like using the arithmetic functions of the CPU 101. This processing constitutes a software control unit including various functional modules of the sheet folding unit 20. The combination of the software control unit thus constituted and hardware resources mounted on the sheet folding unit 20 constitutes a functional block that realizes the functions of the sheet folding unit 20. In other words, the CPU 101, RAM 102, ROM 103, and HDD 104 constitute a controller 100 that controls the operation of the sheet folding unit 20.

[0049] The I / F 105 is an interface that connects the conveying motor 22c, the folding motor 23c, the guide motor 26c, the sheet sensors 28a, 28b, and 28c, the rotary encoders 22z and 23z, and the operation panel 110 to the common bus 109. The controller 100 acquires information from the sheet sensors 28a, 28b, and 28c, the rotary encoders 22z and 23z, and the operation panel 110 through the I / F 105, and operates the conveying motor 22c, the folding motor 23c, and the guide motor 26c.

[0050] 6 illustrates only the components of the sheet folding unit 20, the controller 100 may also control the operations of the image forming unit 12 and the sheet binding unit 30. The controller 100 may operate the sheet folding unit 20 in conjunction with the image forming unit 12 and the sheet binding unit 30 by communicating with a controller that controls the operation of the image forming unit 12 and a controller that controls the operation of the sheet binding unit 30.

[0051] The operation panel 110 includes an operation unit that accepts operations from a user and a display (notification unit) that notifies the user of information. The operation unit includes, for example, hard keys, a touch panel superimposed on the display, etc. The operation panel 110 acquires information from an operator through the operation unit and provides the information to the operator through the display. Note that the notification unit is not limited to a display, and may be an LED lamp, a speaker, etc.

[0052] [Second fold processing] Fig. 7 is a flowchart of the double fold process. Fig. 8 is a diagram showing the movement of the sheet folding unit 20 in the double fold process. Fig. 9 is a diagram showing the behavior of the sheet S when the position of the guide plate 26 is switched. The double fold process is a process for applying an inner fold at the folding position C1 in Fig. 5(A). The folding method of the sheet S may be instructed by the user via the operation panel 110, or may be instructed by an external device via a communication network.

[0053] Controller 100 starts the double folding process shown in FIG. 7 in response to the supply of sheet S from image forming unit 12 via input interface IN (i.e., first sensor 28a is turned ON). First, controller 100 switches guide plate 26 from the second position to the first position by rotating guide motor 26c in the forward direction. However, if guide plate 26 is already in the first position, this process is omitted. Controller 100 also rotates conveying motor 22c and folding motor 23c in the forward direction, thereby rotating conveying roller pair 22, first folding roller 23, second folding roller 24, and third folding roller 25 in the forward direction (S701).

[0054] In step S701, the conveying speed of the pair of conveying rollers 22 and the conveying speed of the first folding roller 23 and the second folding roller 24 are set to the same speed (speed V1). The conveying speed refers to the distance that the pair of rollers nip and rotate the sheet S to convey the sheet S per unit time. That is, the conveying speed of the pair of conveying rollers 22 corresponds to the circumferential speed of the drive roller 22a. On the other hand, the conveying speed of the first folding roller 23 and the second folding roller 24 corresponds to the circumferential speed of the first folding roller 23. If the gear ratio between the drive gear 29a and the driven gear 29b and the gear ratio between the drive gear 29c and the driven gear 29d are the same and the diameters of the drive roller 22a and the first folding roller 23 are the same, the controller 100 may rotate the conveying motor 22c and the folding motor 23c at the same rotation speed.

[0055] 8A, the sheet S nipped by the conveying roller pair 22 is conveyed in the conveying direction, passes through the slit 26a of the guide plate 26 in the first position, and is nipped at the first nip N1. The controller 100 then maintains the state of step S701 until the leading edge of the sheet S passes through the first nip N1 and the folding position C1 reaches a predetermined position (S702: No). The controller 100 determines that the folding position C1 has reached the predetermined position when, for example, the cumulative value of the pulse signals of the rotary encoder 22z since the first sensor 28a turned ON has reached a predetermined value, or when the cumulative value of the pulse signals of the rotary encoder 23z since the second sensor 28b turned ON has reached a predetermined value.

[0056] The predetermined position is a position where the sheet S can pass through the second nip N2 with the folding position C1 as the leading edge in step S703, which will be described later. The predetermined position is a position downstream in the conveying direction from the slit 26a of the guide plate 26 (a position closer to the first nip N1). In addition, when the folding position C1 reaches the predetermined position, the leading edge of the sheet S from the folding position C1 is nipped by the first nip N1, and the trailing edge of the sheet S from the folding position C1 is nipped by the conveying roller pair 22.

[0057] Next, in response to the fact that folding position C1 has reached the predetermined position (S702: Yes), controller 100 reverses the rotation of folding motor 23c and guide motor 26c to switch guide plate 26 from the first position to the second position, and reversely rotates first folding roller 23 until folding position C1 passes second nip N2 (S703). As a result, as shown in Figures 8(B) and 9(A), sheet S enters second nip N2 with folding position C1 as the leading edge, and is inward-folded at folding position C1.

[0058] 9A, when the folding position C1 passes through the second nip N2 and reaches the position facing the third sensor 28c, the leading edge side of the sheet S from the folding position C1 is nipped by the first nip N1, and the trailing edge side of the sheet S from the folding position C1 is nipped by the conveying roller pair 22.

[0059] Next, in response to the folding position C1 passing through the second nip N2 and the third sensor 28c being turned ON (S704: Yes), the controller 100 rotates the guide motor 26c in the forward direction, the conveying motor 22c in the forward direction, and the folding motor 23c in the forward direction (S705). As a result, the guide plate 26 is switched from the second position to the first position, the conveying roller pair 22 conveys the rear end side of the sheet S beyond the folding position C1 in the conveying direction, the first folding roller 23 and the second folding roller 24 convey the front end side of the sheet S beyond the folding position C1 in the conveying direction, and the first folding roller 23 and the third folding roller 25 send out the portion of the sheet S including the folding position C1 to the main conveying path Ph1.

[0060] Here, in step S705, controller 100 makes the conveying speed (speed V3) of first folding roller 23 faster than the conveying speed (speed V2) of conveying roller pair 22. As a result, as shown in FIGS. 9B to 9D, the leading edge side of sheet S relative to folding position C1 is conveyed faster than the trailing edge side of sheet S relative to folding position C1, and sheet S is conveyed in the conveying direction while the fold at folding position C1 is unfolded. Furthermore, controller 100 gradually switches the position of guide plate 26 in conjunction with the rotation of each of rollers 22 to 24 so that guide plate 26, which switches from the second position to the first position, does not pull sheet S nipped in second nip N2. That is, while switching guide plate 26 from the second position to the first position, controller 100 rotates conveying roller pair 22 forward and rotates first folding roller 23 forward at a conveying speed faster than conveying roller pair 22.

[0061] Here, as long as V3>V2 is satisfied, V2=0 or V2<0 may be satisfied. That is, in step S705, the controller 100 may stop the conveying roller pair 22 or may rotate them in the direction opposite to the forward rotation. The same applies to step S1205 in FIG. 12, which will be described later. In addition, the magnitude relationship between V1, V2, V3, and V4, which will be described later, is not particularly limited.

[0062] Then, the controller 100 continues the state of step S705 until a predetermined time has elapsed (S706: No). The predetermined time is the time required for the folding position C1 of the sheet S to be pulled out from the second nip N2 toward the main transport path Ph1. In other words, the predetermined time is the time required for the fold at the folding position C1 to pass through the first nip N1 in an unfolded state. Note that the controller 100 may determine that the folding position C1 of the sheet S has been pulled out from the second nip N2 toward the main transport path Ph1 based on the cumulative value of the pulse signal of the rotary encoder 23z, instead of the predetermined time.

[0063] Next, in response to a predetermined time having elapsed since execution of step S705 (S706: Yes), the controller 100 rotates the conveying motor 22c and the folding motor 23c in the forward direction (S707). In step S707, the controller 100 equalizes the conveying speed (speed V4) of the first folding roller 23 and the conveying speed (speed V4) of the pair of conveying rollers 22. As a result, the sheet S, the fold of which has been opened at folding position C1, passes through the first nip N1 in the conveying direction and is discharged to the sheet binding unit 30. Then, in response to the second sensor 28b being turned OFF (i.e., the trailing edge of the sheet S has passed the position facing the second sensor 28b) (S708: Yes), the controller 100 stops the conveying motor 22c and the folding motor 23c, thereby completing the double folding process.

[0064] 7, the controller 100 can realize the double folding process of folding the sheet S in half by changing the steps from step S703 onwards. First, in step S703, the controller 100 rotates the conveying motor 22c forward, rotates the folding motor 23c reversely, and rotates the guide motor 26c reversely. As a result, the sheet S conveyed by the conveying roller pair 22, the first folding roller 23, and the second folding roller 24 is guided to the second nip N2 by the guide plate 26 in the second position. Next, in response to the trailing edge of the sheet S passing the position of the third sensor 28c (i.e., the third sensor 28c is turned OFF), the controller 100 rotates the conveying motor 22c, the folding motor 23c, and the guide motor 26c forward. As a result, the folded sheet S returns from the return conveying path Ph2 to the main conveying path Ph1 through the confluence B, with the inward-folded folding position C1 at the front, and is discharged to the sheet binding unit 30 through the conveying roller pair 22, the guide plate 26 in the first position, and the first nip N1.

[0065] [Inner three-fold processing] FIG. 10 is a flowchart of the inner triple fold process. FIG. 11 is a diagram showing the movement of the sheet folding unit 20 in the inner triple fold process. The inner triple fold process is a process of applying inner folds at folding positions C2 and C3 in FIG. 5(A). In other words, the inner triple fold process is a process of performing a double fold process at folding positions C2 and C3 instead of folding position C1. Below, a detailed description of the commonalities with the double fold process will be omitted, and the following description will focus on the differences.

[0066] First, the controller 100 continues the process of step S701 until the folding position C2 reaches a predetermined position (S702: No). Next, the controller 100 executes the processes of steps S703-S707 for the folding position C2 (S1001). As a result, the sheet S is folded inward at the folding position C2, and the crease at the folding position C2 is opened.

[0067] Next, the controller 100 determines whether the process of step S1001 has been performed on the two folding positions C2 and C3 (i.e., whether the folding process has been performed twice) (S1002). If the controller 100 determines that the process of step S1001 has not been performed on the folding position C3 (S1002: No), the controller 100 continues the process of step S707 until the folding position C3 reaches a predetermined position (S702: No). Next, when the folding position C3 reaches the predetermined position (S702: Yes), the controller 100 performs the processes of steps S703-S707 on the folding position C3 (S1001). As a result, the sheet S is inward-folded at the folding positions C2 and C3 (FIG. 11A), and the folds at the folding positions C2 and C3 are unfolded (FIG. 11B).

[0068] Next, if the controller 100 determines that two folding processes have been performed (S1002: Yes), it continues the state of step S707 until the second sensor 28b turns OFF (S708: No). Then, in response to the second sensor 28b turning OFF (S708: Yes), the controller 100 stops the conveying motor 22c and the folding motor 23c, and ends the inner triple fold process. That is, in the inner triple fold process, the controller 100 inward-folds the sheet S at a plurality of folding positions C2 and C3 that are offset in the conveying direction, unfolds the folds at each of the plurality of folding positions C2 and C3, and discharges the sheet S.

[0069] 5(B), the controller 100 may shift the folding position of each of the multiple sheets S sequentially supplied to the sheet folding unit 20 in the conveying direction. More specifically, the controller 100 may set the distance between the folding positions C2 and C3 of the first sheet S as a first distance, the distance between the folding positions C2 and C3 of the second sheet S as a second distance, and the distance between the folding positions C2 and C3 of the third sheet S as a third distance. Note that the first distance < the second distance < the third distance. This makes it easier to bundle the multiple sheets S and fold them inward in three.

[0070] The controller 100 can realize an inner three-fold process for folding the sheet S in three by changing step S1001 of the inner three-fold process shown in FIG. 10 in the same way as the above-described two-fold process.

[0071] [Outer Tri-Fold Processing / Z-Fold Processing] FIG. 12 is a flowchart of the outer triple fold process. FIG. 13 is a diagram showing the movement of the sheet folding unit 20 when folding the binding position C2 outward. FIG. 14 is a diagram showing the movement of the sheet folding unit 20 when folding the binding position C3 inward. FIG. 15 is a diagram showing the behavior of the sheet S when the guide plate 26 is switched from the first position to the second position. The outer triple fold process is a process of applying an outer fold at folding position C2 in FIG. 5(A) and applying an inner fold at folding position C3. Note that if an outer fold is applied at folding position C1 and an inner fold is applied at folding position C4 in the process of FIG. 12, a so-called "Z-fold" fold is applied. Hereinafter, a detailed description of the commonalities with the double fold process and the inner triple fold process will be omitted, and the differences will be mainly described.

[0072] In response to the supply of sheet S from image forming unit 12 via input interface IN (i.e., first sensor 28a being turned ON), controller 100 starts the outer triple fold process shown in FIG. 12. First, controller 100 reverses guide motor 26c to switch guide plate 26 from the first position to the second position. However, if guide plate 26 is already in the second position, this process is omitted. Controller 100 also rotates conveyance motor 22c in the forward direction to rotate conveyance roller pair 22 in the forward direction. Furthermore, controller 100 reverses folding motor 23c to rotate first folding roller 23, second folding roller 24, and third folding roller 25 in the reverse direction (S1201).

[0073] In step S1201, the controller 100 sets the conveying speed of the conveying roller pair 22 and the conveying speeds of the first folding roller 23 and the third folding roller 25 to the same speed (speed V1). As a result, as shown in FIG. 13A, the sheet S nipped by the conveying roller pair 22 is conveyed in the conveying direction, passes through the slit 26a of the guide plate 26 in the second position, and is nipped at the second nip N2. The controller 100 continues the state of step S1201 until the leading edge of the sheet S passes through the second nip N2 and the folding position C2 reaches a predetermined position (S1202: No). The controller 100 determines that the folding position C2 has reached the predetermined position when, for example, the cumulative value of the pulse signals of the rotary encoder 22z since the first sensor 28a turned ON has reached a predetermined value, or when the cumulative value of the pulse signals of the rotary encoder 23z since the third sensor 28c turned ON has reached a predetermined value.

[0074] The predetermined position is a position where the sheet S can pass through the first nip N1 with the folding position C2 as the leading edge in step S1203, which will be described later. The predetermined position is a position downstream in the conveying direction from the slit 26a of the guide plate 26 (a position closer to the second nip N2). In addition, when the folding position C2 reaches the predetermined position, the leading edge of the sheet S from the folding position C2 is nipped by the second nip N2, and the trailing edge of the sheet S from the folding position C2 is nipped by the conveying roller pair 22.

[0075] Next, in response to the fact that folding position C2 has reached the predetermined position (S1202: Yes), controller 100 rotates folding motor 23c and guide motor 26c in the forward direction to switch guide plate 26 from the second position to the first position, and rotates first folding roller 23 in the forward direction until folding position C2 passes first nip N1 (S1203). As a result, as shown in Figures 13(B) and 15(A), sheet S enters first nip N1 with folding position C2 as the leading edge, and is outward-folded at folding position C2.

[0076] 15A, when the folding position C2 passes through the first nip N1 and reaches the position facing the second sensor 28b, the leading edge side of the sheet S from the folding position C2 is nipped by the second nip N2, and the trailing edge side of the sheet S from the folding position C2 is nipped by the conveying roller pair 22.

[0077] Next, in response to folding position C2 passing through first nip N1 and second sensor 28b being turned ON (S1204: Yes), controller 100 rotates guide motor 26c in the reverse direction, conveying motor 22c in the forward direction, and folding motor 23c in the reverse direction (S1205). As a result, guide plate 26 is switched from the first position to the second position, conveying roller pair 22 conveys the trailing edge side of sheet S beyond folding position C2 in the conveying direction, first folding roller 23 and third folding roller 25 convey the leading edge side of sheet S beyond folding position C2 toward junction B, and first folding roller 23 and second folding roller 24 send the portion of sheet S including folding position C2 to second nip N2.

[0078] Here, in step S1205, controller 100 makes the conveying speed (speed V3) of first folding roller 23 faster than the conveying speed (speed V2) of conveying roller pair 22. As a result, as shown in FIGS. 15(B) to 15(D), the leading edge side of sheet S from folding position C2 is conveyed faster than the trailing edge side of sheet S from folding position C2, and sheet S is pulled into return conveying path Ph2 while the fold at folding position C2 is unfolded. Furthermore, controller 100 gradually switches the position of guide plate 26 in conjunction with the rotation of each of rollers 22 to 24 so that guide plate 26, which is switching from the first position to the second position, does not pull sheet S nipped in first nip N1. That is, while switching guide plate 26 from the first position to the second position, controller 100 rotates conveying roller pair 22 forward and rotates first folding roller 23 reversely at a conveying speed faster than conveying roller pair 22.

[0079] Then, the controller 100 continues the state of step S1205 until a predetermined time has elapsed (S1206: No). The predetermined time is the time required for the folding position C2 of the sheet S to be pulled out from the first nip N1 toward the second nip N2. In other words, the predetermined time is the time required for the fold at the folding position C2 to pass through the second nip N2 in an unfolded state. Note that the controller 100 may determine that the folding position C2 of the sheet S has been pulled out from the first nip N1 toward the second nip N2 based on the cumulative value of the pulse signal from the rotary encoder 23z, instead of the predetermined time.

[0080] Next, in response to a predetermined time having elapsed since execution of step S1205 (S1206: Yes), controller 100 rotates conveying motor 22c forward and rotates folding motor 23c reversely (S1207). In step S1207, controller 100 equalizes the conveying speed (speed V4) of first folding roller 23 and the conveying speed (speed V4) of conveying roller pair 22. As a result, as shown in FIG. 13(C), sheet S, whose crease at folding position C2 has been unfolded, passes through second nip N2 and returns from return conveying path Ph2 to main conveying path PH1 via junction B.

[0081] Then, the controller 100 continues the state of step S1207 until the trailing edge of the sheet S passes the position facing the third sensor 28c (i.e., the third sensor 28c turns OFF) (S1208: No). However, the controller 100 switches the guide plate 26 from the second position to the first position by first rotating the guide motor 26c forward at the timing when the first sensor 28a turns ON. Next, in response to the third sensor 28c turning OFF (S1208: Yes), the controller 100 executes a second fold process for the folding position C3 (S1209). As a result, as shown in FIG. 14, the folding position C3 is folded inward, the fold at the folding position C3 is unfolded, and the sheet is discharged to the sheet binding unit 30.

[0082] Note that the controller 100 can achieve the outward three-folding process of folding the sheet S in three by changing step S1204 and subsequent steps of the outward three-folding process shown in FIG. 12. First, the controller 100 maintains the state of step S1203 until folding position C3 reaches a predetermined position. Next, instead of the processes of steps S1205 to S1209, the controller 100 executes the above-described double folding process for folding position C3, thereby discharging the outward three-folded sheet S to the sheet binding unit 30. Furthermore, if the above-described process is executed for folding positions C1 and C4 instead of folding positions C2 and C3, the Z-folded sheet S is discharged to the sheet binding unit 30.

[0083] [Operation of sheet binding unit 30] Next, the operation of the sheet binding unit 30 will be described with reference to Figs. 16 to 20. Fig. 16 is a diagram showing the state of the sheet binding unit 30 until the sheet S reaches the pair of conveying rollers 36. Fig. 17 is a diagram showing the state of the sheet binding unit 30 when the sheet S is discharged to the discharge tray 32 without being bound. Fig. 18 is a diagram showing the state of the sheet binding unit 30 when performing the binding process. Fig. 19 is a diagram of the sheet binding unit 30 in Fig. 18(B) as seen from the thickness direction of the sheet S. Fig. 20 is a diagram showing the state of the sheet binding unit 30 when the bound sheet bundle Sb is discharged to the discharge tray 32.

[0084] 16, the sheet binding unit 30 conveys the sheet S supplied from the sheet folding unit 20 in the conveying direction along the conveying path Ph3 by rotating the conveying roller pairs 33 to 35 in the forward direction. At this time, the conveying roller pair 36 is in a state where the drive roller 36a and the driven roller 36b are separated from each other.

[0085] Next, when the sheet S is not to be bound, the sheet binding unit 30 clamps the sheet S between the drive roller 36a and the driven roller 36b, as shown in Fig. 17(A). Then, as shown in Fig. 17(B), the sheet binding unit 30 discharges the sheet S onto the discharge tray 32 by rotating the conveying roller pair 36 forward.

[0086] On the other hand, when binding the sheets S, as shown in Fig. 18, the sheet binding unit 30 rotates the striking rollers 38 and the return rollers 39 in contact with the sheets S after they have passed through the pair of conveying rollers 35, thereby storing the sheets S in the internal tray 37. As shown in Fig. 19, the sheet binding unit 30 aligns the widthwise positions of the sheets S stored in the internal tray 37 by moving the side fences 41L, 41R in the width direction. The sheet binding unit 30 then repeats the processes shown in Figs. 16, 18, and 19 to form a sheet bundle Sb on the internal tray 37.

[0087] Next, the sheet binding unit 30 binds the sheet bundle Sb supported on the internal tray 37 by driving the binding processing section 42. Next, as shown in FIG. 20A, the sheet binding unit 30 clamps the sheet bundle Sb between the drive roller 36a and the driven roller 36b. Then, as shown in FIG. 17B, the sheet binding unit 30 discharges the sheet bundle Sb onto the discharge tray 32 by rotating the conveying roller pair 36 and the return roller 39 forward.

[0088] [Effects of the embodiment] According to the above embodiment, it is possible to crease the sheet S in various ways (for example, a double fold, a three-fold inside, a three-fold outside, and a Z-fold). Furthermore, the sheet folding unit 20 according to the above embodiment can discharge the sheet S in a folded state simply by fine-tuning the processes shown in FIGS. 7, 10, and 12. This allows the process of creasing the sheet S and the process of folding the sheet S to be performed by a single sheet folding unit 20. As a result, it is possible to achieve a sheet folding unit 20 that can flexibly respond to various user needs.

[0089] Furthermore, according to the above embodiment, the second folding roller 24 and the third folding roller 25 are brought into contact with the first folding roller 23 so as to rotate drivenly, and the guide plate 26 is configured to switch from the first position to the second position, thereby making it possible to reduce the size of the sheet folding unit 20.

[0090] Furthermore, according to the above embodiment, as shown in FIG. 5(B), by shifting the folds of the multiple sheets S in the conveying direction, wrinkles are less likely to occur in the sheets S when the user folds a stack of the sheets S.

[0091] Furthermore, according to the above embodiment, the movable range of the guide plate 26 is limited by the stoppers 27a and 27b, and the torque limiter 29g is included in the drive force transmission mechanism 29, so that the movable range of the guide plate 26 can be limited with a simple configuration. This allows the sheet folding unit 20 to be further miniaturized.

[0092] However, the method for limiting the movable range of the guide plate 26 is not limited to the stoppers 27a and 27b. FIG. 21 illustrates another example of limiting the movable range of the guide plate 26. The sheet folding unit 20 illustrated in FIG. 21 may include posture sensors 27c and 27d instead of the stoppers 27a and 27b. The posture sensor 27c outputs a detection signal when the guide plate 26 is in a first posture and stops outputting the detection signal when the guide plate 26 is in a posture different from the first posture. The posture sensor 27d outputs a detection signal when the guide plate 26 is in a second posture and stops outputting the detection signal when the guide plate 26 is in a posture different from the second posture. The controller 100 may stop driving the guide motor 26c when a detection signal is output from one of the posture sensors 27c and 27d. In this case, the torque limiter 29g is omitted.

[0093] Furthermore, according to the above embodiment, by arranging the folding rollers 23 to 25 and the guide plate 26 on the opposite side of the partition wall 21a from the driving force transmission mechanism 29, it is possible to prevent the sheet S from being contaminated by dust emitted from the driving force transmission mechanism 29. It is also possible to prevent dust emitted from the sheet S from clogging the driving force transmission mechanism 29 and impeding the smooth transmission of the driving force.

[0094] Furthermore, the sheet folding unit 20 according to the above embodiment has particularly advantageous effects when installed in the internal space 13 of the image forming apparatus 10, where space is limited. However, the installation in the internal space 13 is not limited to the sheet folding unit 20. Furthermore, the installation position of the sheet folding unit 20 is not limited to the internal space 13.

[0095] [Variation 1] Figure 22 is a diagram showing the internal configuration of the punch hole punching unit 50 (punch hole punching section). The punch hole punching unit 50 shown in Figure 22 is configured to be detachable to a position in the internal space 13 from which the sheet folding unit 20 has been removed. In other words, the image forming apparatus 10 is configured so that the sheet folding unit 20 and the punch hole punching unit 50 can be replaced depending on the application. Note that the configuration of the punch hole punching unit 50 is already well known, so a detailed description will be omitted, but it may be configured as follows, for example.

[0096] As shown in FIG. 22, the punch hole punching unit 50 includes a housing 51, a sheet sensor 52, punch pins 53a and 53b, and a punch scrap hopper 54. The housing 51 has an internal space that houses the components of the punch hole punching unit 50. The internal space of the housing 51 also has a conveyance path formed therein through which sheets on which images have been formed by the image forming unit 12 pass. The sheet sensor 52 detects that the sheet S supplied from the image forming unit 12 has reached a predetermined position. The punch pins 53a and 53b punch holes in the sheet S detected by the sheet sensor 52. Punch scraps that fall off the sheet S fall into the punch scrap hopper 54. This achieves the punching process of punching holes in the sheet S.

[0097] [Variation 2] 23 is another example of a hardware configuration diagram of the image forming apparatus 10. For example, as shown in FIG. 23, the image forming apparatus 10 may include a controller 200 that controls the image forming unit 12 and the operation panel 110, in addition to the controller 100 shown in FIG.

[0098] The controller 200 may include, for example, a CPU, RAM, ROM, and HDD, similar to the controller 100. The controller 200 may also control the image forming unit 12 and the operation panel 110 via an I / F 205. The controllers 100 and 200 may be capable of communicating with each other. The controllers 100 and 200 may cooperate to control the operation of the image forming apparatus 10.

[0099] [Variation 3] FIG. 24 is an external view of the image forming system 1. As shown in FIG. 24, the image forming system 1 is composed of an image forming apparatus 10, a sheet folding apparatus 20', and a sheet binding apparatus 30'. The image forming apparatus 10, the sheet folding apparatus 20', and the sheet binding apparatus 30' are each independently operable and configured to be connectable to one another. The configuration of the sheet folding apparatus 20' is common to the sheet folding unit 20 described above, and the configuration of the sheet binding apparatus 30' is common to the sheet binding unit 30 described above.

[0100] Fig. 25 is a hardware configuration diagram of the image forming system 1. For example, as shown in Fig. 25, the image forming system 1 does not include the controller 100, and a controller 200 centrally controls the components of the image forming apparatus 10 and the sheet binding unit 30. The configuration of the controller 200 is the same as that shown in Fig. 23. The controller 200 may operate the image forming system 1 by controlling the operation of the components of the image forming apparatus 10 via an I / F 205 and controlling the operation of the components of the sheet binding unit 30 via an I / F 105.

[0101] The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist thereof. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims.

[0102] In the above-described embodiment, the position of the guide plate 26 is the first position shown in Fig. 3(A) and the second position shown in Fig. 3(B), but this is not limitative. Fig. 3(A) may be the second position and Fig. 3(B) may be the first position.

[0103] The contents of the present invention are as follows, for example. <1> a pair of conveying rollers that convey the sheet in a conveying direction; a first folding roller disposed downstream of the pair of conveying rollers in the conveying direction; a second folding roller that forms a first nip with the first folding roller and is driven by the rotation of the first folding roller; a third folding roller that forms a second nip with the first folding roller and is driven by the rotation of the first folding roller; a guide member disposed between the pair of conveying rollers and the first nip in the conveying direction, the guide member being switchable between a first position for guiding the sheet to the first nip and a second position for guiding the sheet to the second nip; a controller for controlling the pair of conveying rollers; The controller With the sheet sandwiched in the first nip, the guide member is switched from the first position to the second position, and the sheet is folded in the second nip; or, with the sheet sandwiched in the second nip, the guide member is switched from the second position to the first position, and the sheet is folded in the first nip; This is a sheet folding device characterized in that, when the sheet is folded in the first nip or the second nip, the conveying speed of the first folding roller is made faster than the conveying speed of the pair of conveying rollers. <2> the above <1> In the sheet folding device described in The sheet folding device is characterized in that the controller rotates the pair of conveying rollers and the first folding roller in opposite directions while the sheet is folded into the first nip or the second nip. <3> the above <1> or the above <2> In the sheet folding device described in the pair of conveying rollers are capable of rotating forward to convey the sheet in the conveying direction, the second folding roller is disposed opposite the first folding roller across the main conveyance path, the third folding roller is disposed opposite the first folding roller across a return conveyance path that branches off from the main conveyance path at a branching portion upstream of the first folding roller in the conveyance direction and merges with the main conveyance path at a merging portion upstream of the branching portion in the conveyance direction, The first folding roller a forward rotation that conveys the sheet nipped in the first nip in the conveying direction and sends the sheet nipped in the second nip from the return conveying path to the main conveying path; This sheet folding device is configured to be capable of reverse rotation, transporting the sheet nipped in the first nip in the opposite direction to the transport direction and pulling the sheet nipped in the second nip into the return transport path. <4> the above <3> In the sheet folding device described in The controller the guide member is kept in the first position, and the pair of conveying rollers and the first folding roller are rotated forward at the same conveying speed until the leading edge of the sheet passes through the first nip and the folding position reaches a predetermined position; In response to the folding position reaching the predetermined position, the guide member is switched from the first position to the second position, and the first folding roller is rotated in a reverse direction until the folding position passes through the second nip, thereby folding the sheet at the folding position; This sheet folding device is characterized in that, in response to the folding position passing through the second nip, the guide member is switched from the second position to the first position, the pair of conveying rollers is rotated forward, and the first folding roller is rotated forward at a conveying speed faster than that of the pair of conveying rollers, thereby spreading the fold at the folding position and discharging the sheet. <5> the above <4> In the sheet folding device described in The sheet folding device is characterized in that the controller folds the sheet at a plurality of the folding positions that are shifted in the conveying direction, unfolds the folds at each of the plurality of folding positions, and discharges the sheet. <6> the above <3> In the sheet folding device described in The controller the guide member is in the second position, the conveying roller pair is rotated forward, and the first folding roller is rotated backward until the leading edge of the sheet passes through the second nip and the folding position reaches a predetermined position; In response to the folding position reaching the predetermined position, the guide member is switched from the second position to the first position, and the first folding roller is rotated forward until the folding position passes through the first nip, thereby folding the sheet at the folding position; In response to the folding position passing through the first nip, the guide member is switched from the first position to the second position, and the pair of conveying rollers is rotated forward and the first folding roller is rotated backward at a conveying speed faster than that of the pair of conveying rollers until a predetermined time has elapsed, thereby spreading the fold at the folding position and allowing the sheet to enter the return conveying path; This sheet folding device is characterized in that, upon the lapse of the predetermined time, the guide member is switched from the second position to the first position, and the pair of conveying rollers and the first folding roller are rotated forward at the same conveying speed, thereby discharging the sheet. <7> the above <1> or the above <6> In the sheet folding device described in any one of The sheet folding device is characterized in that the controller shifts the folding position of each of the plurality of sheets supplied to the sheet folding device in sequence in the conveying direction. <8> the above <1> or the above <7> a sheet folding device according to any one of the above; and a binding device that binds together the plurality of sheets to which creases have been applied by the sheet folding device. <9> an image forming unit that forms an image on a sheet; The sheet on which the image is formed by the image forming unit is folded. <1> or the above <8> and a sheet folding device according to any one of the above. <10> an image forming unit that forms an image on a sheet; a pair of conveying rollers that convey the sheet that has passed through the image forming unit in a conveying direction; a first folding roller disposed downstream of the pair of conveying rollers in the conveying direction; a second folding roller that forms a first nip with the first folding roller and is driven by the rotation of the first folding roller; a third folding roller that forms a second nip with the first folding roller and is driven by the rotation of the first folding roller; a guide member disposed between the pair of conveying rollers and the first nip in the conveying direction, the guide member being switchable between a first position for guiding the sheet to the first nip and a second position for guiding the sheet to the second nip; a controller for controlling the pair of conveying rollers; The controller With the sheet sandwiched in the first nip, the guide member is switched from the first position to the second position, and the sheet is folded in the second nip; or, with the sheet sandwiched in the second nip, the guide member is switched from the second position to the first position, and the sheet is folded in the first nip; This is an image forming system characterized in that, when the sheet is folded in the first nip or the second nip, the conveying speed of the first folding roller is controlled to be faster than the conveying speed of the pair of conveying rollers. [Explanation of symbols]

[0104] 1: Image forming system 10: Image forming device 11, 21, 31, 51: Housing 12: Image forming unit 13:Inner body space 20,20': Sheet folding unit 21a: Bulkhead 22: Pair of conveying rollers 22c: Transport motor 23: First folding roller 23c: Folding motor 24: Second folding roller 24x: Rotation axis 25: Third folding roller 25x: Rotation axis 26: Guide plate 26a: Slit 26a1, 26a2: Guide surface 28a: First sensor 28b: Second sensor 28c: Third sensor 29: Driving force transmission mechanism 30,30': Sheet binding unit 32: Output tray 33-36: Transport roller pair 37: Internal tray 38: Hitting Roller 39: Return roller 40L, 40R: End fence 41L, 41R: Side fence 42: Binding processing section 50: Hole punching unit 52: Sheet sensor 53a, 53b: Piercing pin 54: Punch waste hopper 100,200: Controller 101: CPU 102: RAM 103:ROM 104: HDD 105,205 :I / F 109: Common bus 110: Operation panel [Prior art documents] [Patent documents]

[0105] [Patent Document 1] Japanese Patent Application Publication No. 2019-163165 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-298185

Claims

1. a pair of conveying rollers that convey the sheet in a conveying direction; a first folding roller disposed downstream of the pair of conveying rollers in the conveying direction; a second folding roller that forms a first nip with the first folding roller and is driven by the rotation of the first folding roller; a third folding roller that forms a second nip with the first folding roller and is driven by the rotation of the first folding roller; a guide member disposed between the pair of conveying rollers and the first nip in the conveying direction, the guide member being switchable between a first position for guiding the sheet to the first nip and a second position for guiding the sheet to the second nip; a controller for controlling the pair of conveying rollers; The controller With the sheet sandwiched in the first nip, the guide member is switched from the first position to the second position, and the sheet is folded in the second nip; or, with the sheet sandwiched in the second nip, the guide member is switched from the second position to the first position, and the sheet is folded in the first nip; A sheet folding device, characterized in that, when the sheet is folded in the first nip or the second nip, the conveying speed of the first folding roller is made faster than the conveying speed of the pair of conveying rollers.

2. The sheet folding device according to claim 1, The sheet folding device is characterized in that the controller rotates the pair of conveying rollers and the first folding roller in opposite directions while the sheet is folded in the first nip or the second nip.

3. The sheet folding device according to claim 1, the pair of conveying rollers are capable of rotating forward to convey the sheet in the conveying direction, the second folding roller is disposed opposite the first folding roller across the main conveyance path, the third folding roller is disposed opposite the first folding roller across a return conveyance path that branches off from the main conveyance path at a branching portion upstream of the first folding roller in the conveyance direction and merges with the main conveyance path at a merging portion upstream of the branching portion in the conveyance direction, The first folding roller a forward rotation that conveys the sheet nipped in the first nip in the conveying direction and sends the sheet nipped in the second nip from the return conveying path to the main conveying path; The sheet folding device is configured to be capable of reverse rotation, conveying the sheet nipped in the first nip in a direction opposite to the conveying direction and pulling the sheet nipped in the second nip into the return conveying path.

4. The sheet folding device according to claim 3, The controller the guide member is kept in the first position, and the pair of conveying rollers and the first folding roller are rotated forward at the same conveying speed until the leading edge of the sheet passes through the first nip and the folding position reaches a predetermined position; In response to the folding position reaching the predetermined position, the guide member is switched from the first position to the second position, and the first folding roller is rotated in a reverse direction until the folding position passes through the second nip, thereby folding the sheet at the folding position; a guide member for switching from the second position to the first position in response to the folding position passing through the second nip, while rotating the pair of conveying rollers forward and rotating the first folding roller forward at a conveying speed faster than that of the pair of conveying rollers, thereby spreading the fold at the folding position and discharging the sheet.

5. The sheet folding device according to claim 4, The sheet folding device is characterized in that the controller folds the sheet at a plurality of the folding positions that are shifted in the conveying direction, and unfolds the folds at each of the plurality of folding positions, and discharges the sheet.

6. The sheet folding device according to claim 3, The controller the guide member is in the second position, the conveying roller pair is rotated forward, and the first folding roller is rotated backward until the leading edge of the sheet passes through the second nip and the folding position reaches a predetermined position; In response to the folding position reaching the predetermined position, the guide member is switched from the second position to the first position, and the first folding roller is rotated forward until the folding position passes through the first nip, thereby folding the sheet at the folding position; In response to the folding position passing through the first nip, the guide member is switched from the first position to the second position, and the pair of conveying rollers is rotated forward and the first folding roller is rotated backward at a conveying speed faster than that of the pair of conveying rollers until a predetermined time has elapsed, thereby spreading the fold at the folding position and allowing the sheet to enter the return conveying path; a sheet folding device configured to switch the guide member from the second position to the first position in response to the lapse of the predetermined time, and to eject the sheet by rotating the pair of conveying rollers and the first folding roller forward at the same conveying speed.

7. The sheet folding device according to claim 1, The sheet folding device, wherein the controller shifts the folding position of each of the plurality of sheets supplied to the sheet folding device in the conveying direction.

8. The sheet folding device according to claim 1; a binding device that binds together the plurality of sheets to which creases have been applied by the sheet folding device.

9. an image forming unit that forms an image on a sheet; an image forming apparatus comprising: a sheet folding device according to claim 1 that folds the sheet on which the image has been formed by the image forming unit;

10. an image forming unit that forms an image on a sheet; a pair of conveying rollers that convey the sheet that has passed through the image forming unit in a conveying direction; a first folding roller disposed downstream of the pair of conveying rollers in the conveying direction; a second folding roller that forms a first nip with the first folding roller and is driven by the rotation of the first folding roller; a third folding roller that forms a second nip with the first folding roller and is driven by the rotation of the first folding roller; a guide member disposed between the pair of conveying rollers and the first nip in the conveying direction, the guide member being switchable between a first position for guiding the sheet to the first nip and a second position for guiding the sheet to the second nip; a controller for controlling the pair of conveying rollers; The controller With the sheet sandwiched in the first nip, the guide member is switched from the first position to the second position, and the sheet is folded in the second nip; or, with the sheet sandwiched in the second nip, the guide member is switched from the second position to the first position, and the sheet is folded in the first nip; an image forming system, characterized in that, when the sheet is folded in the first nip or the second nip, the conveying speed of the first folding roller is controlled to be faster than the conveying speed of the pair of conveying rollers.

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