JP7262223B2 - Sheet folding device and image forming system - Google Patents

Description

The present invention relates to a sheet folding device that folds a sheet and an image forming system that includes this sheet folding device.

2. Description of the Related Art Conventionally, a sheet folding device is widely known that performs folding processing at a predetermined position on a sheet on which an image is formed by an image forming device such as a copier or printer. The folding process includes folding the sheet in half at the center position, folding the sheet into three by folding the sheet inward at two points, and folding the sheet in three by alternately folding the sheet inward and outward, so-called Z-folding.

Such a sheet folding device includes a pair of conveying rollers on the upstream side of a horizontal upper guide plate, a pair of paper folding rollers on the downstream side, and a paper piece guiding/deflecting member (that is, a pushing member) on the upstream side of the pair of paper folding rollers. Disposed paper folding devices are known (see, for example, Patent Document 1). In this device, the paper piece guiding/deflecting member moves from a second position in which the paper piece guiding/deflecting member is retracted obliquely downward on the upstream side of the paper folding roller pair to a first position in which the leading edge is brought close to the paper piece inlet of the paper folding roller pair. A predetermined position of the piece of paper hanging in the space in front of the folding roller is drawn into the paper piece drawing-in port, and the piece of paper is folded in half or Z-fold.

A sheet conveying roller is provided on the upstream side of the sheet conveying path in which the lower guide plate and the upper guide plate face each other, and a sheet bending roller is provided on the downstream side of the sheet conveying path. A sheet processing apparatus has been proposed that includes a pressing member (that is, a thrusting member) that is movable between a second position that is retracted obliquely downward on the upstream side, and similarly performs folding in half and Z-folding on a sheet material. (See Patent Document 2, for example). From the second position, the pressing member presses the sheet hanging down from the notch opened between the sheet conveying roller and the sheet bending roller against the upper guide plate with the roller at the tip thereof, and moves the sheet on the upper guide plate. It moves along the plate to a first position, guides the folding position of the sheet material to the nip of the sheet folding roller, and folds it by its rotation.

JP-A-2002-68583 JP-A-2005-67741

In both of the conventional devices described in Patent Documents 1 and 2, when Z-folding a sheet, the sheet is folded from the upstream side by the pair of conveying rollers while the pair of folding rollers nips the leading edge of the sheet (the downstream end in the conveying direction) and stops. The sheet is continuously fed and curved into a loop shape in the space opened below the conveying path.

In this manner, when the sheet is curved from a straight shape to a loop shape, the folding roller is rotated by a slight amount in the conveying direction to hold the leading edge of the sheet. In this case, the portion of the sheet that has been fed before the pair of folding rollers stop after the leading edge of the sheet is nipped protrudes downstream in the sheet conveying direction from the predetermined position of the sheet superimposed on the leading edge side of the sheet. This protruding portion, the so-called tab, impairs the appearance of the Z-folded sheet, causing a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet folding device that shortens the length of a protruding portion (tab) in a Z-folded sheet and can produce a good-looking Z-folded sheet. With the goal.

In order to solve the above-described problems, a sheet folding device according to the present invention includes a conveying roller that conveys a sheet in a predetermined conveying direction , and a conveying roller that is arranged downstream of the conveying roller in the conveying direction and nips the sheet to form a crease. a pair of reversible folding rollers having a nip portion forming a transport path through which a sheet transported by the transport roller is transported from the transport roller to the pair of folding rollers along the transport direction; A loop forming space formed below the conveying path pushes the sheet conveyed by the conveying roller so that the sheet hangs down from the conveying path upstream of the pair of folding rollers in the direction. a pushing member movable from the upstream side in the conveying direction toward the pushing position where the sheet is nipped at a predetermined position by the pair of folding rollers; The folding roller in the feeding operation is arranged such that, when the leading portion of the conveyed sheet in the carrying direction passes through the nip portion, the crease formation reference portion preset in the leading portion is positioned at the nip portion. folding position adjusting means for rotating the pair of folding rollers in reverse at a speed lower than the normal rotation speed of the pair, wherein the folding position adjusting means pushes the sheet pushed by the pushing member moved to the pushing position. and the crease formation reference portion nipped at the nip portion are overlapped and nipped, and the pair of folding rollers are rotated forward again to form a crease at a predetermined position of the sheet. As a result, the creases are neatly arranged at a constant crease position.

In this case, when the pair of folding rollers rotates in the same direction as the pair of conveying rollers to pass the leading portion of the sheet, the rotational speed of the pair of folding rollers is the same as the rotational speed of the pair of conveying rollers. , the skew that occurs when the leading edge of the sheet comes into contact with the pair of folding rollers is prevented.

In one embodiment, when the pair of folding rollers is reversed so that the crease forming reference portion is positioned at the nip portion, the crease position adjusting means adjusts the folding rollers according to the position of the crease forming reference portion of the sheet. Adjust the conveying amount in the opposite direction by the reverse drive of the pair.

From another aspect, an image forming system of the present invention includes an image forming apparatus that forms an image on a sheet, and the sheet folding apparatus that folds the sheet fed from the image forming unit. This provides an image forming system with high productivity.

According to the sheet folding apparatus of the present invention, when the leading portion of the sheet transported by the transporting rollers in the feeding operation by forward rotation of the pair of folding rollers passes the nip portion, the leading portion is set in advance. Fold position adjusting means for rotating the pair of folding rollers in reverse at a speed slower than the forward rotation speed of the pair of folding rollers in the feeding operation so that the fold forming reference portion is positioned at the nip portion, wherein the folding position adjusting means When the leading portion of the sheet passes through the nip portion due to the forward rotation of the pair of rollers, the folding roller pair is positioned such that the crease formation reference portion preset at the leading portion is positioned at the nip portion. Controls quantitative reversal drive. As a result , when the sheet is folded, the crease-forming portion of the sheet that is abutted against the thrusting member is overlapped with the crease-forming reference portion and nipped. be.

1 shows an overall configuration diagram of an image forming system to which the present invention is applied; FIG. 1 shows a schematic block diagram of a sheet folding device according to the present invention; FIG. (a) shows a perspective view showing the entire drive mechanism of the sheet folding device, and (b) shows an enlarged view of the essential part thereof. FIG. 4 shows an end view of a sheet that has been tri-folded (Z-folded) by a sheet folding device; FIG. 2 is a block diagram showing a control configuration of the sheet folding device; FIG. 4 shows a flowchart for explaining the overall processing operation of the sheet folding device. (a) to (f) are cross-sectional views showing the folding process of the sheet folding device in order of steps. 4 shows a flowchart for explaining registration processing of the sheet folding device. 4 shows a flowchart for explaining a loop forming process of the sheet folding device. 4 shows a flow chart for explaining the movement of the veneer to the retracted position. 4 shows a flowchart for explaining the creasing process of the sheet folding device. 4 shows a flow chart for explaining the movement of the sliced plate to the thrusting position. 4 shows a flow chart for explaining the movement of the veneer to the guide position.

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.

[Image forming system]
FIG. 1 shows the overall configuration of an image forming system to which the present invention is applied. The image forming system shown in the figure comprises an image forming apparatus A, a sheet post-processing apparatus B, and a sheet folding apparatus C connected therebetween. A sheet on which an image has been formed by the image forming apparatus A is conveyed through the sheet folding apparatus C, and is received by the sheet post-processing apparatus B in a discharge tray. The image forming apparatus A, sheet post-processing apparatus B, and sheet folding apparatus C will be described below.

[Image forming apparatus]
The image forming apparatus A is of a type that forms an image on a sheet by a known electrostatic printing mechanism. not shown). An image reading section 5 consisting of a scanner unit and an automatic document feeding section 6 thereon are integrally provided on the upper portion of the device housing 1 . The image forming apparatus A of the present embodiment is of a so-called internal paper discharge type, and has a U-shaped front face defined largely between the image forming section 3, the paper discharge section 4, and the image reading section 5 in FIG. A transport relay unit 7 is arranged in the paper space. In addition to the electrostatic printing mechanism described above, the image forming apparatus A can employ various other image forming mechanisms such as an inkjet image forming method, an offset printing method, and a silk printing method.

A plurality of sheet feeding cassettes 2 a and 2 b having different sheet sizes are detachably provided in the apparatus housing 1 in the sheet feeding section 2 . The sheet feeding unit 2 containing the sheet for image formation feeds out the sheet of the size instructed by the control unit from the corresponding sheet feeding cassette to the sheet feeding path 8 . A registration roller 9 is provided in the paper feed path 8, and the sheets whose leading edges are aligned by the registration roller are fed to the downstream image forming section 3 at a predetermined timing.

The image forming section 3 has an electrostatic drum 10 and a print head, a developing device, a transfer charger, etc. arranged therearound. The print head is composed of, for example, a laser emitter and forms an electrostatic latent image on the electrostatic drum 10 . The developer adheres toner ink to the electrostatic latent image to form a toner image, which is transferred to a sheet by the transfer charger. The sheet onto which the toner image has been transferred is conveyed to a fixing device 11 where it is heated and pressurized to fix the toner image.

The paper ejection path 12 branches downstream into a first paper ejection path 13 on the upper side in FIG. 1 and a second paper ejection path 14 on the lower side. The first paper ejection path 13 and the second paper ejection path 14 are connected to an upper first paper ejection port 15 and a lower second paper ejection port 16 that open into the paper ejection space, respectively.

The sheet discharge section 4 can be provided with a sheet circulation path (not shown). The sheet circulation path connects the paper ejection path 12 to the paper feed path 8 on the downstream side of the fixing device 11 on the upstream side of the registration rollers 9, for example. The image-formed sheet sent out from the image forming section 3 to the sheet discharging path 12 is switched back to the sheet circulation path by reversing the sheet discharging roller of the sheet discharging path 12, and the surface thereof is turned upside down, and the sheet is sent to the image forming section again. 3, images can be formed on both sides of the sheet.

As shown in FIG. 1, the transport relay unit 7 has a substantially L-shape when viewed from the front. and a second relay portion 18 extending to the left side of the device housing 1 . The upper surface of the second relay portion 18 forms a substantially flat sheet ejection tray 19 within the sheet ejection space.

A first relay path 20 is provided inside the first relay section 17 , and a first sheet inlet 21 thereof is connected to a first sheet discharge port 15 of the sheet discharge section 4 . It is arranged above the sheet ejection tray 19 so as to open to the sheet ejection space. The first relay path 20 is provided near the first sheet outlet 22 with a carry-out roller driven by a motor built in the first relay section 17 . The image-formed sheet conveyed from the paper discharge section 4 through the first paper discharge path 13 passes through the first relay path 20 and is conveyed to the sheet discharge tray 19 in the paper discharge space by the discharge roller. be.

A second relay path 23 is provided inside the second relay section 18 , and a second sheet entrance 24 thereof is arranged so as to be connected to the second paper discharge port 16 of the paper discharge section 4 . A second sheet outlet 25 of the second relay path 23 opens substantially on the same plane as the left side surface of the apparatus housing 1, and is connected to a sheet inlet of the sheet folding apparatus C as described later. The second relay path 23 is provided with a plurality of conveying rollers that are driven by a motor built in the second relay section 18 to convey the sheet. The image-formed sheet conveyed from the paper discharge section 4 through the second paper discharge path 14 passes through the second relay path 23 and is sent to the sheet folding device C by the conveying rollers.

The image reading section 5 includes a platen 26 on which a document sheet is placed, a reading carriage 27 that moves along the platen, and an optical reading means 28 such as a CCD device. The document paper on the platen 26 is scanned and optically read by the reading carriage 27 , and the optical image generated thereby is photoelectrically converted into image data by the optical reading means 28 . The automatic document feeder 6 automatically feeds the document sheets set in the paper feed tray 29 to the platen 26 .

With the above-described configuration, the image forming apparatus A reads a document sent from the document feeding section 5 by the image reading section 4, and forms an image on the sheet sent from the paper feeding section 3 by the image forming section 2 according to the read image data. do. A sheet on which an image has been formed is conveyed from the sheet discharging section 4 through the first sheet discharging path 13 and then through the first relay path 20 when the folding processing by the sheet folding device C and the post-processing by the sheet post-processing device B are not performed. It passes through and is carried out to the sheet ejection tray 19 in the sheet ejection space. When performing the folding process and/or the post-processing on the sheet on which the image has been formed, the sheet is conveyed from the sheet discharging section 4 through the second sheet discharging path 14, passes through the second relay path 23, and is sent to the sheet folding device. sent to C.

[Sheet post-processing device]
As shown in FIG. 1, the sheet post-processing apparatus B has a first conveying path 101 for conveying a sheet from the sheet folding device, and second and third conveying paths branched from the first conveying path. 102, 103, a post-processing device such as the stapling unit ST1, and a binding processing tray 104. FIG. On one side (the left side in FIG. 1) of the housing 100, first and second discharge trays 105 and 106 for stacking and storing sheets discharged from the sheet post-processing apparatus B are vertically spaced apart. there is The sheet post-processing device B is arranged so that the sheet inlet 107 of the first conveying path 101 is connected to the sheet outlet of the sheet folding device C, which will be described later.

The first paper discharge tray 105 is arranged below the paper discharge port 108 of the second transport path 102 that opens on the side surface of the housing 100 . Sheets sent from the sheet folding device C are conveyed from the first conveying path 101 to the second conveying path 102 when the sheet post-processing device B does not perform stapling processing by the stapling unit ST1 and/or other post-processing. , is discharged from the discharge port 108 to the first discharge tray 105 as it is.

A discharge port 109 of the third conveying path 103 is arranged above the binding tray 104 so as to face the sheet mounting surface of the binding tray 104 . A sheet sent from the sheet folding device C is conveyed from the first conveying path 101 to the third conveying path 103 in the case of performing the stapling process by the stapling unit ST1, and is loaded onto the stapling processing tray 104 from the discharge port 109 thereof. discharged on the surface. A plurality of sheets stacked on the binding processing tray 104 are stapled into a sheet bundle by the stapling unit ST1, conveyed from the binding processing tray, and discharged from the downstream end to the second paper discharge tray 106 below. be.

[Overall Configuration of Sheet Folding Device]
In the sheet folding device C, as shown in FIG. 2, a transport path 32 is formed inside a housing 31 from a sheet carry-in port 32a on the image forming apparatus A side to a sheet discharge port 32b on the sheet post-processing device B side. there is In the conveying path 32, a registration roller pair 33, which is a pair of conveying rollers for taking in and conveying the sheet carried into the carry-in port 32a into the conveying path 32, is arranged on the upstream side along the sheet conveying direction, and a folding roller pair 34 is arranged on the downstream side. , and a thrust plate 35, which is a thrust member, is disposed between the pair of rollers. The sheet folding device C has the sheet carry-in port 32a at the second sheet outlet 25 of the transport relay unit 7 installed in the image forming apparatus A, and the sheet discharge port at the sheet carry-in port 107 of the sheet post-processing device B, as described above. 32b are arranged to connect to each other.

Further, an additional folding mechanism 36 can optionally be provided in the vicinity of the sheet discharge port 32b of the transport path 32. FIG. In a folding mechanism such as the sheet folding device C, in order to reliably fold the conveyed sheet at the folding line position, providing an additional folding mechanism that presses the sheet at the folding line position downstream after the folding process is provided. Conventionally well known to those skilled in the art.

[Registration roller pair]
The registration roller pair 33 consists of an upper driving roller 33a and a lower driven roller 33b, which are arranged across the transport path 32 in the figure. The two rollers 33a, 33b are pressed against each other by, for example, suitable spring means (not shown) so that the driven roller 33b follows the rotation of the drive roller 33a by a registration motor, which will be described later, in the opposite direction. rotate to

The sheet sent out from the transport relay unit 7 of the image forming apparatus A by the discharge roller pair 37 near the second sheet exit 25 has its leading edge pressed against the roller surface of the registration roller pair 33 that stops rotating. By abutting against the nip portion 38, the tip positions are aligned. The sheet whose skew has been corrected by aligning the leading edge position is conveyed along the conveying path 32 toward the pair of folding rollers 34 by driving the pair of registration rollers 33 at a predetermined timing.

In another embodiment, the registration roller pair 33 can be replaced by a discharge roller (corresponding to the discharge roller pair 37 in FIG. 2) that discharges the sheet from the image forming apparatus A to the sheet folding device C. As a result, the number of parts of the sheet folding device C can be reduced, the manufacturing cost can be reduced, and the size of the entire device can be reduced in the sheet conveying direction. In this case, the discharge roller pair 37 preferably has a function of aligning the leading edge positions of the sheets carried into the transport path 32 as described above.

[Folding roller pair]
The folding roller pair 34 is composed of an upper upper folding roller 34a and a lower lower folding roller 34b, which are arranged across the transport path 32 in the drawing. Both rollers 34a and 34b are pressed against each other by, for example, suitable spring means (not shown) in order to nip and fold the leading edge and crease of the sheet sent from the registration roller pair 33 as will be described later. In addition, in such a press-contact state, they are synchronously rotated in opposite directions by a common folding roller drive motor, which will be described later.

The folding roller pair 34 is arranged so that the nip portion 38 of the registration roller pair 33 is positioned above a tangent line 39a passing through the nip portion 39, which is the pressure contact portion of the roller surfaces. In the embodiment of FIG. 2, the tangent line 39a and the tangent line 38a passing through the nip portion 38 of the registration roller pair 33 are both oriented generally horizontally, and the tangent line 38a is oriented with a certain vertical offset such that the tangent line 38a passes above the tangent line 39a. It is

[Conveyance route]
As shown in FIG. 2, the transport path 32 includes a sheet transport path 41 extending along the sheet transport direction from a sheet inlet 32a to a registration roller pair 33, and a central transport path 42 extending from the registration roller pair to the folding roller pair 34. and a sheet delivery path 43 extending from the pair of folding rollers to the sheet delivery port 32b.

The sheet carry-in path 41 includes an upper carry-in guide 41a and a lower carry-in guide 41b arranged vertically opposite each other along the sheet conveying direction so as to guide the leading edge of the sheet to be carried in to the nip portion 38 of the registration roller pair 33. have. As described above, the upper carry-in guide 41a is arranged so that when the leading edge of the sheet is brought into contact with the nip portion 38 of the registration roller pair 33 to align the leading edge positions, the sheet fed from the upstream side to the discharge roller pair 37 is positioned along the sheet carry-in path. In order to secure a loop-shaped bendable space within 41, the area near the registration roller pair 33 is greatly expanded upward toward the entrance side.

As shown in FIG. 2, the central conveying path 42 is arranged vertically in opposition along the sheet conveying direction so as to guide the sheet whose leading edge is aligned by the pair of registration rollers 33 to the nip portion 39 of the pair of folding rollers 34 . It has a transport guide 45 and a lower transport guide 46 . The sheet is conveyed through the central conveying path 42 while being regulated from both sides in the thickness direction by the upper and lower conveying guides 45 and 46 (in this example, from above and below).

As described above, the tangent line 38a that passes through the nip portion 38 of the registration roller pair 33 and the tangent line 39a that passes through the nip portion 39 of the folding roller pair 34 are arranged horizontally with a vertical height difference. , a first horizontal portion 45a horizontally extending downstream along the tangent line 38a, a second horizontal portion 45b horizontally extending upstream along the tangent line 39a, and a horizontal line extending from the upstream side to the downstream side so as to connect the tangent lines 38a and 39a. and a sloped portion 45c that slopes downward to the side.

As shown in FIG. 2, the inclined portion 45c is formed in a straight line from the upstream end of the second horizontal portion 45b to the upper right side in the figure. The inclined portion 45c and the second horizontal portion 45b intersect linearly, and at the connecting portion thereof, there is a convex portion 47 which is formed by a relatively large obtuse-angled corner portion and projects generally downward in the central conveying path 42. formed. Similarly, the connecting portion between the inclined portion 45c and the first horizontal portion 45a is also formed at a relatively large obtuse angle.

In another embodiment, the connecting portion between the inclined portion 45c and the second horizontal portion 45b can be curved. In this case, the protruding portion 47 is formed by a curved portion that protrudes generally downward in the central conveying path 42 . A connecting portion between the inclined portion 45c and the first horizontal portion 45a can be similarly curved. In another embodiment, the convex portion 47 can be formed by a member separate from the second horizontal portion 45b and the inclined portion 45c of the upper conveying guide 45. FIG.

In this embodiment, as shown in the figure, the first horizontal portion 45a, the inclined portion 45c, and the upstream portion of the second horizontal portion 45b are formed by one continuous first upper conveying guide member, and the second A downstream portion of the horizontal portion 45b is formed by another second upper conveying guide member. The first and second upper conveying guide members are arranged substantially continuously so as not to interfere with sheet conveying in the central conveying path 42 . Further, the first upper transport guide member can be formed by a plurality of substantially continuous guide members, and the boundary between the first upper transport guide member and the second upper transport guide member is also positioned as shown in FIG. It can be set in various other ways.

The lower conveying guide 46 includes a first lower guide portion 46a extending from the registration roller pair 33 to a predetermined position downstream in the sheet conveying direction, and a first lower guide portion 46a extending from the folding roller pair 34 to a predetermined position upstream along the sheet conveying direction. and a second lower guide portion 46b extending to. The first and second lower guide portions 46a and 46b are spaced apart and fixed to the housing 31 so as to define a large gap 48 therebetween along the sheet conveying direction. A gap 48 between the first and second lower guide portions 46a and 46b is selectively opened and closed by a veneer 35 horizontally movable toward a nip portion 39 of the pair of folding rollers 34, as will be described later.

A relatively large loop forming space 50 is provided below the gap 48 of the lower conveying guide 46, as shown in FIG. When the veneer 35 is retracted (indicated by solid lines in FIG. 2) to open the gap 48 , the sheet in the central conveying path 42 can hang down from the gap 48 into the loop forming space 50 . When the veneer 35 advances (indicated by an imaginary line 35' in FIG. 2) and the gap 48 is closed, the sheet fed from the registration roller pair 33 does not hang down in the loop forming space 50 and is can be conveyed toward the pair of folding rollers 34 along the .

The first lower guide portion 46a includes a first horizontal guide portion 51a extending horizontally downstream from the registration roller pair 33 generally facing the first horizontal portion 45a of the upper transport guide 45, and further downstream from there, It has a first inclined guide portion 51b that is inclined substantially parallel to the inclined portion 45c of the upper conveying guide halfway. The downstream end of the first inclined guide portion 51b defines the position where the sheet begins to hang down when the gap 48 is opened. In this embodiment, as illustrated, the downstream end of the first inclined guide portion 51b is positioned above a tangent line 39a passing through the nip portion 39 of the folding roller pair 34. As shown in FIG.

The second lower guide portion 46b includes a second horizontal guide portion 52a horizontally extending upstream from the folding roller pair 34, a second inclined guide portion 52b inclined downward upstream from the second horizontal guide portion, and the second horizontal guide portion 52b. and a vertical guide portion 52c extending generally vertically downward from the second angled guide portion. The second horizontal guide portion 52a cooperates with the second horizontal portion 45b of the upper conveying guide 45 to regulate the sheet from both sides in the thickness direction, i.e., the vertical direction, while folding the leading edge of the sheet to the nip portion of the pair of rollers 34. Guide to 39. The second inclined guide portion 52 b is inclined toward the loop forming space 50 so as to guide the sheet hanging down in the loop forming space 50 to the nip portion 39 of the folding roller pair 34 . The vertical guide portion 52c secures the dimension of the loop forming space 50 and, together with the second inclined guide portion 52b, separates the sheet hanging in the loop forming space 50 from the folding roller pair 34 side.

When the veneer 35 is at the retracted position, the sheet fed from the pair of registration rollers 33 to the central conveying path 42 passes the downstream end of the first inclined guide portion 51b and passes through the gap 48 opened downward from the tip of the sheet. It hangs down linearly in the loop forming space 50 . On the other hand, when the gap 48 is opened with the leading edge of the sheet nipped by the folding roller pair 34 and the folding roller pair stopping rotation, the sheet in the central conveying path 42 is moved into the gap 48 as will be described later. It bends and hangs down in loop form space 50 through.

The sheet carry-out path 43 has an upper carry-out guide 43a and a lower carry-out guide 43b that are vertically opposed to each other along the sheet carrying direction so as to guide the folded sheet to the sheet carry-out exit 32b. In front of the sheet outlet 32b, for example, an additional folding mechanism having a plurality of rolling elements that move on the lower outlet guide 43b in the sheet width direction perpendicular to the sheet conveying direction to additionally fold the creases of the folded sheet. 36 is provided.

[Veneer board]
The veneer 35 is formed of a flat plate member extending in the sheet width direction of the central conveying path 42, as shown in FIGS. The veneer 35 is horizontally arranged at substantially the same height as the nip portion 39 of the folding roller pair 34 . Further, the thrust plate 35 is horizontally movable between a retracted position below the first lower guide portion 46a indicated by solid lines in FIG. 2 and a guide position and thrust position indicated by imaginary lines 35' and 35''. ing.

When the veneer 35 is at the retracted position, as shown in the figure, the gap 48 of the lower conveying guide 46 is completely opened, and the central conveying path 42 is opened to the loop forming space 50 below at the second path portion. be. Therefore, the sheet in the central conveying path 42 can hang down from the central conveying path 42 into the loop forming space 50 as will be described later.

At the guide position indicated by the imaginary line 35', the veneer 35 completely closes the gap 48 of the lower conveying guide 46 and forms a part of the lower conveying guide 46 by facing the upper conveying guide 45 vertically. As a result, the sheet in the central conveying path 42 is guided through the second path portion without hanging down in the loop forming space 50, and is conveyed from the first path portion to the third path portion.

At the thrust position of the imaginary line 35'', the thrust plate 35 enters between the second horizontal portion 45b of the upper conveying guide 45 and the second horizontal guide portion 52a of the second lower guide portion 46b at the third path portion. This thrusting position is a position where the tip of the thrusting plate 35 folds the sheet and feeds it into the nip portion 39 of the pair of rollers 34 .

3(a) and 3(b) show the configuration of the veneer 35 in more detail. As shown in the figure, in this embodiment, four pairs of folding rollers 34 each comprising upper and lower folding rollers 34a and 34b are attached to upper and lower roller shafts 55 and 56, respectively. The four pairs are arranged symmetrically, two pairs on each side of the center position along the axial direction of the roller shafts 55 and 56 . At the tip of the veneer 35, four notches 57 having shapes and dimensions corresponding to the shapes of the four pairs of folding rollers 34 are formed along the sheet width direction corresponding to the positions of the four pairs of folding rollers 34. recessed.

The movement of the sliced plate 35 between the retracted position, the guide position and the thrusting position is performed by driving a sliced plate drive motor MT3 of the drive mechanism shown in FIG. 3, which will be described later. The driving of the veneer driving motor MT3 is controlled by the control section 120 shown in FIG. 5 as described later.

[Driving Mechanism of Sheet Folding Device]
3A and 3B show drive mechanisms 58 to 60 of the registration roller pair 33, the folding roller pair 34, and the cutting plate 35 of the sheet folding device C. FIG. The registration roller pair 33 is attached so that the drive roller 33a rotates integrally with a roller shaft 61 that is rotatably installed in the sheet width direction. In the pair of folding rollers 34, the upper and lower folding rollers 34a and 34b are attached to roller shafts 55 and 56, which are also rotatably installed in the sheet width direction, so as to rotate together.

The drive mechanism 58 for the registration roller pair 33 includes a registration roller drive motor MT1, a drive pulley P1 attached to its rotating shaft, a driven pulley P2 attached to one end of the roller shaft 61 of the drive roller 33a, and both pulleys P1. , and P2. The driving force of the registration roller driving motor MT1 is transmitted from its rotating shaft to the driving roller 33a through a transmission mechanism including a driving pulley P1, a timing belt TB1 and a driven pulley P2.

The driving mechanism 59 of the folding roller pair 34 includes a folding roller driving motor MT2, a driving pulley P3 attached to its rotating shaft, a driven pulley P4 attached to the roller shaft 56 of the lower folding roller 34b, both pulleys P3, and a timing belt TB2 that is stretched between P4. Further, the driving mechanism 59 includes a gear Z1 coaxially and integrally rotatably attached to the roller shaft 56, and a gear Z2 which is coaxially and integrally rotatably attached to the roller shaft 55 of the upper folding roller 34a and meshes with the gear 1. and

The driving force of the folding roller driving motor MT2 is transmitted from its rotating shaft to the lower folding roller 34b via a transmission mechanism including a driving pulley P3, a timing belt TB2, and a driven pulley P4. Further, the driving force of the folding roller driving motor MT2 is transmitted from the roller shaft 56 to which the driven pulley P4 is attached to the upper folding roller 34a via gears Z1 and Z2 that mesh with each other. As a result, the upper folding roller 34a and the lower folding roller 34b rotate synchronously in directions opposite to each other, and the sheet nipped between the folding rollers can be conveyed in the sheet conveying direction in cooperation.

A drive mechanism 60 for the sliced plate 35 includes a sliced plate driving motor MT3, a driving pulley P5 attached to its rotating shaft, a rotating shaft 62 extending in the sheet width direction, and a driven pulley P6 attached to one end thereof. , a timing belt TB3 entrained between both pulleys P5 and P6; and a second rack and pinion mechanism 64 provided in.

The first rack-and-pinion mechanism 63 has a first pinion 63a that is coaxially and integrally rotatable on the one end side of the rotating shaft 62 and is attached to the inside of the driven pulley P6, and is attached to one end of the veneer 35. , and a first rack 63b that meshes with the first pinion 63a. The second rack-and-pinion mechanism 64 includes a second pinion 64a that is similarly attached to the other end of the rotating shaft 62 so as to be coaxially rotatable together with the second pinion 64a, and is attached to the other end of the veneer 35 to form a second pinion. and a second rack 64b that meshes with 64a. The first and second racks 63b, 64b are arranged so that the sliced board 35 moves horizontally as the first and second pinions 63a, 64a rotate.

The drive force of the veneer drive motor MT3 is transmitted from its rotary shaft to the first and second pinions 63a, 63b via a transmission mechanism consisting of a drive pulley P5, a timing belt TB3 and a driven pulley P6. As a result, the first and second racks 63b and 64b move synchronously in the same direction and cooperate to move the veneer 35 in the horizontal direction.

[Control Configuration of Sheet Folding Device]
The sheet folding device C of the present embodiment configured as described above is suitable for Z-folding a sheet into three. FIG. 4 shows an example of the sheet SH Z-folded by the sheet folding device C from the sheet width direction. In the figure, the sheet SH is formed with a first crease 202 at a position of a predetermined length upstream from a leading edge (downstream end) 201 in the sheet conveying direction, and folded back from there to a position of a predetermined length to the downstream side. A second crease 203 is formed in the .

FIG. 5 conceptually shows the control configuration of the sheet folding device C. As shown in FIG. The control unit 120 includes a control board including a CPU, a RAM that is a work memory area during operation, and a ROM that stores a program for executing the folding processing operation of the sheet folding device C. , first to third detection sensors S1, S2, S3 provided along the transport path 32 are connected.

The first detection sensor S1 is arranged in front of the registration roller pair 33 in the sheet carry-in path 41, and detects the leading edge of the sheet carried in from the image forming apparatus A through the sheet carry-in port 32a. The second detection sensor S<b>2 is arranged in front of the folding roller pair 34 on the central transport path 42 and detects the leading edge of the sheet transported from the registration roller pair 33 to the folding roller pair 34 . The third detection sensor S3 detects the position of the thrust plate 35 moving between the retracted position, the guide position and the thrust position as described above. These first to third detection sensors S1, S2, and S3 output respective detection signals to the control section 120 in real time.

In addition to the registration roller drive motor MT1, folding roller drive motor MT2, and sliced plate drive motor MT3, the control unit 120 is further connected to the additional folding drive motor MT4 when the additional folding mechanism 36 is provided. there is Based on the detection signals from the first to third detection sensors S1, S2, S3 and the above various information received from the control unit 121 of the image forming apparatus A, the drive motors MT1, MT2, MT3 and optionally MT4 are driven. , and controls and executes the conveyance of the sheet on the conveyance path 32 and the folding processing operation of the sheet folding device C. FIG.

Further, the control section 120 is connected to the control section 121 of the image forming apparatus A via the sheet post-processing apparatus B. FIG. The control unit 121 is connected to an input unit and a display unit (not shown) provided on the setting panel D of the image forming apparatus A. FIG. For example, information such as the sheet type set by the user on the setting panel D and the folding processing mode executed by the sheet folding device C is transmitted from the control unit 121 to the control unit 120 via the sheet post-processing device B. .

Further, the control unit 120 can transmit information on sheet conveyance, folding processing, and the like performed in the sheet folding apparatus C to the control unit 121 of the image forming apparatus A via the sheet post-processing apparatus B in real time. can. If the information received from the control unit 120 includes information that is undesirable or requires caution or warning, such as defective sheet conveyance or defective folding in the sheet folding device C, the control unit 121 notifies the user of the information. For example, the display section of the setting panel D can be used to notify.

The CPU of the control unit 120 executes a program stored in the ROM to control the driving of each of the drive motors MT1, MT2, MT3 and optionally MT4. The function of the fold position adjusting means 120a is realized.

When the sheet reaches the pair of folding rollers 34 by the feeding operation of the pair of registration rollers 33, the folding position adjusting means 120a adjusts the leading portion of the sheet that has already passed through the nip portion 39 and is held by the pair of folding rollers 34 at this time. The driving of the driving motor MT2 is controlled so that the folding roller pair 34 is reversed by a predetermined amount so that the reference portion (folding reference portion) that overlaps with the folding line 203 when folding is performed is positioned at the nip portion 39 . As a result, the second crease 203 abutted by the thrust plate 35 overlaps the crease formation reference portion and is nipped at the nip portion 39, and the crease 203 is formed at a predetermined position of the sheet. This crease formation reference portion is set in advance at any position of the leading portion passing through the nip portion 39. In this example, the crease formation reference portion is set at the downstream edge of the sheet in the carry-in direction, that is, the leading edge of the sheet. , a crease is formed by aligning the leading edge of the sheet with the second crease 203 . Therefore, in this case, the fold position adjusting means 120 a performs control to reverse the folding roller pair 34 by a predetermined amount until the leading edge of the sheet is positioned at the nip portion 39 .

[Processing operation of sheet folding device]
The folding processing operation of the sheet folding device C will be described below. The sheet folding device C is preset with a folding processing (Z-folding) mode for performing folding processing of folding (Z-folding) a sheet in three and a non-folding mode for not folding a sheet. The user determines whether or not to fold the image-formed sheet before starting image formation on the sheet in the image forming apparatus A. If folding is to be performed, the folding processing mode is selected in the input section of the setting panel D. Select and enter The input of the folding processing mode is stored in the control unit 121 of the image forming apparatus A as sheet information of the sheet to be folded.

The overall processing operation of the sheet folding apparatus C will be schematically described with reference to the flowchart of FIG. First, the control section 120 of the sheet folding apparatus C acquires sheet information from the control section 121 of the image forming apparatus A via the sheet post-processing apparatus B (step ST01).

If the sheet information acquired from the control unit 121 of the image forming apparatus A includes the selection of the folding processing mode or the execution instruction of the folding processing (Y in step ST02), the process proceeds to step ST03 and subsequent steps to execute the folding processing. If the sheet information from the image forming apparatus A does not include the selection of the folding processing mode or the execution instruction of the folding processing, or includes the instruction not to execute the folding processing, the process proceeds to step ST06 to execute the unfolding processing.

In the non-folding process of step ST06, the veneer 35 is placed at the guide position (35'), and the registration roller pair 33 and the folding roller pair 34 are driven to rotate in this state. As a result, the sheet from the image forming apparatus A passes through the conveying path 32 as it is without being folded, and is carried out to the sheet post-processing apparatus B. FIG.

The folding process from steps ST03 to ST05 includes, as a whole, registration processing by the registration roller pair 33 (step ST03), folding loop processing by the folding roller pair 34 (step ST04), and crease formation by the veneer 35 and the folding roller pair 34. The process (step ST05) is performed in three stages. In the registration process, the leading edge of the sheet carried into the sheet folding device C is aligned to correct the skew of the sheet. In the folding loop process, a loop for forming a fold line is formed on the leading edge side of the sheet. In the crease forming process, the folding roller pair 34 forms a crease in the looped sheet.

The processing in steps ST03 to ST05 will be specifically described below with reference to FIGS. 7 to 13. FIG. (a) to (f) of FIG. 7 show the process in which the sheet folding apparatus C loads the sheet from the image forming apparatus A, conveys the sheet, and folds the sheet in the order of steps.

[Resist treatment]
FIG. 7A shows a state in which the leading edges of the sheets are aligned in the registration process of the sheet folding device C. FIG. The registration process is performed, for example, according to the procedure shown in the flowchart of FIG.

The control unit 120 waits a predetermined time from when the first detection sensor S1 detects the leading edge of the sheet carried into the sheet carry-in path 41 and turns on (Y in step ST10) while the registration roller pair 33 is stopped rotating. wait until has elapsed. This predetermined time is a necessary and sufficient time for bringing the leading edge of the sheet into contact with the nip portion 38 of the registration roller pair 33 and aligning the leading edge positions. This time can be determined in advance based on, for example, test results and the like, and set in the control unit 120 .

After the predetermined time has elapsed (Y in step ST11), the control unit 120 drives the registration roller driving motor MT1 (step ST12) to rotate the registration roller pair 33. FIG. At the same time when the registration roller drive motor MT1 is driven, a folding loop counter, which is a software timer counter, starts counting (step ST13). In this case, the count-up value of the folding loop counter is required to supply an amount of sheets corresponding to the sheet size necessary for the registration roller pair 33 to form folds by driving the registration roller driving motor MT1. Feed amount is set.

At this time, the rotation speed of the registration roller pair 33 is synchronized with the sheet discharge speed in order to reliably receive the sheet discharged from the image forming apparatus A on the upstream side. However, since the sheet ejection speed fluctuates depending on the image forming processing time in image forming apparatus A, control unit 120 rotates at a rotation speed according to the sheet ejection speed information sent from control unit 120 of image forming apparatus A. Control the drive motor MT1 to drive.

When the registration roller pair 33 is rotated, the sheet is transported along the transport path 32 to the folding roller pair 34 as shown in FIG. 7B. At this time, the veneer 35 is arranged at the guide position 35'. Therefore, the leading edge of the sheet is guided along the central conveying path 42 by the upper surface of the thrust plate 35 and sent straight toward the nip portion 39 of the folding roller pair 34 . The sheet whose leading end has passed through the convex portion 47 of the central conveying path 42 is, in the area where the inclined portion 45c and the second horizontal portion 45b of the upper conveying guide 45 are connected in the sheet conveying direction, that is, in the area facing the gap 48. It is pushed downward by the convex portion 47 and curved convexly toward the loop forming space 50 side.

[Fold loop processing]
The folding loop process is executed, for example, according to the procedure shown in the flowchart of FIG. The control unit 120 drives the registration roller drive motor MT1 in step ST13 of FIG. 8, and simultaneously drives the folding roller drive motor MT2 to rotate the folding roller pair 34 (step ST20). As shown in FIG. 7B, immediately upstream of the folding roller pair 34, when the second detection sensor S2 detects the leading edge of the conveyed sheet and is turned on (Y in step ST21), the control unit 120 executes retraction processing for moving the sliced veneer 35 from the guide position to the retraction position (step ST22).

This retreating process of the veneer 35 is executed, for example, according to the procedure shown in the flowchart of FIG. The control unit 120 drives the thrust plate driving motor MT3 in the reverse direction (step ST50) to horizontally move the thrust plate 35 upstream in the sheet conveying direction from the guide position 35' toward the retracted position. The thrust plate 35 of the present embodiment is provided with a detection flag (not shown) at its upstream end in the sheet conveying direction.

When the third detection sensor S3 arranged below the first lower guide portion 46a detects the detection flag of the sliced plate 35 and turns on (Y in step ST51), the sliced plate drive motor MT3 is stopped ( step ST52). As a result, the thrust plate 35 is placed at the retracted position shown in FIG. 7(c), and the gap 48 between the first and second lower guide portions 46a and 46b is completely opened. As a result, the central conveying path 42 is opened to the loop forming space 50 below at the second path portion, as shown in FIG.

Next, the control unit 120 drives the registration roller drive motor MT1 up to a preset first set driving amount from the time when the second detection sensor S2 detects the leading edge of the sheet in step ST21 (step Y in ST23), the folding roller drive motor MT2 is stopped (step ST24). Here, the first set drive amount is the drive amount of the registration roller drive motor MT1 required for the leading edge of the sheet to reach the position where it is nipped by the nip portion 39 of the folding roller pair 34 . The driving amount of the registration roller driving motor MT1 includes the amount of rotation of the motor (the number of rotations of the rotation shaft, the rotation angle, the rotation time, etc.) and the amount of feeding of the sheet by the registration roller pair 33, that is, the amount of rotation of the driving roller 33a (roller shaft 61 rotation number, rotation angle, rotation time, etc.) can be used.

In the present embodiment, the sheet feed amount (conveyance distance) from the position where the leading edge of the sheet is detected by the second detection sensor S2 to the position beyond the nip portion 39 of the folding roller pair 34 by 10 mm corresponds to that. The first set drive amount is set by converting the drive amount of the registration roller drive motor MT1. Therefore, the leading edge of the sheet, which is the crease formation reference portion that overlaps with the crease 203 when the sheet is folded, is located beyond the nip portion 39 .

Therefore, after stopping the folding roller driving motor MT2, the control unit 120 reverses the folding roller pair 34 by a predetermined amount by the folding line position control means 120a, and drives the folding roller driving motor MT2 so that the leading edge of the sheet is positioned at the nip portion 39. is controlled (ST26). The return speed of the folding roller pair 34 for returning the sheet is lower than the speed of the folding roller pair 34 when receiving the sheet into the folding roller pair 34 . Further, even when the folding roller pair 34 reversely conveys the sheet, the folding loop counter continues the counting operation, and the registration roller pair 33 continues conveying the sheet in the folding roller pair 34 direction. . The length of the loop formed by the sheet hanging down in the loop forming space 50 in the conveying direction is determined by the amount of feeding of the sheet by the registration roller pair 33 .

When the folding loop counter counts up (Y in step ST26), the process proceeds to the next folding line forming process (step ST05).
Note that the operation of returning the sheet by reversing the pair of folding rollers 34 by the folding line position control means 120a is controlled so as to be completed before the execution of the next folding line forming process. This is because if the sheet is returned by the pair of folding rollers 34 after the sliced plate 15 (to be described later) moves and comes into contact with the sheet, the position at which the sliced plate 15 contacts the sheet may be displaced.

[Crease forming process]
The crease forming process is performed, for example, according to the procedure shown in the flowchart of FIG. The control unit 120 starts the thrusting process of the sliced plate 35 at the same time as the folding loop counter counts up in step ST26. At this time, the loop forming space 50 has a size suitable for forming a crease in the sheet at a predetermined folding position as shown in FIG. A folded loop FL is formed.

The thrusting process is executed, for example, according to the procedure shown in the flowchart of FIG. First, the sliced plate drive motor MT3 is driven forward (step ST53) to horizontally move the sliced plate 35 toward the folding roller pair 34 side. At this time, the tip of the veneer 35 advances toward the nip portion 39 of the folding roller pair 34 while pushing the position of the second folding line when viewed from the sheet leading edge side of the folding loop FL. The control unit 120 sets the moving speed of the sliced plate 35 to be the same as the sheet conveying speed of the registration roller pair 33 so that the position of the folding loop FL pushed by the tip of the sliced plate 35 does not change while the sliced plate 35 is moving. The veneer driving motor MT3 is controlled as follows.

The upper sheet portion sandwiching the thrust plate 35 is pushed upward by the second horizontal portion 45 b of the upper transport guide 45 . The lower sheet portion is regulated by the second horizontal guide portion 52a of the second lower guide portion 46b, and the leading end portion of the sheet on the upstream side from the nip portion 39 of the folding roller pair 34 is regulated by the second horizontal guide portion. and is regulated from below. As a result, the sheet is prevented from slipping in the sheet conveying direction with the front end of the thrust plate 35 while proceeding downstream along the third path portion, and the second crease against which the thrust plate 35 abuts. It is bent at the folding position (203 in FIG. 4).

When the driving amount of the sliced plate driving motor MT3 reaches the preset second set driving amount (Y in step ST54), the sliced plate driving motor MT3 is stopped (step ST55). As a result, as shown in FIG. 7(e), the tip of the veneer 35 is aligned with the second horizontal guide portion 45b of the upper conveying guide 45 and the second horizontal guide portion 46b of the second lower guide portion 46b at the third path portion. 52a and stop at the thrust position 35″. Thereby, the folding position FP2, which is the second folding line of the sheet, is bent as described above, and the nip portion 39 of the folding roller pair 34 is formed. carried to just before

Here, the second set drive amount is the drive amount of the sliced plate drive motor MT3 required to move the sliced plate 35 from the retracted position to the thrust position 35″. can use the amount of rotation of the motor (the number of rotations of the rotating shaft, the rotation angle, the rotation time, etc.).

After the veneer drive motor MT3 is stopped in step ST55, when the registration roller drive motor MT1 is driven to the preset third set drive amount (Y in step ST31), the control section 120 causes the folding roller drive motor Drive MT2 (step ST32). Here, the third set drive amount is such that the sheet is continuously sent out even after the thrust plate drive motor MT3 is stopped in step ST55, and the folding position FP2 of the sheet is the position where the folding position FP2 of the sheet is caught in the nip portion 39 of the folding roller pair 34. is the driving amount of the registration roller drive motor MT1 that rotates the registration roller pair 33 until the .

When the folding roller pair 34 is rotated by driving the folding roller driving motor MT2, the folding position of the sheet, which is the second fold line, is caught in the nip portion 39 of the folding roller pair 34, as shown in FIG. 7(f). , is bent under pressure between the upper and lower folding rollers 34a and 34b while being conveyed downstream. A second fold F2 (203) is formed on the sheet at a predetermined folding position by this pressure processing. As described above, the folding position FP2 of the sheet is conveyed in a bent state without slipping or shifting in the sheet conveying direction, and is caught in the nip portion 39 of the pair of folding rollers 34 as it is. The position of is stabilized with high accuracy without the conventional variation.

When the folding roller drive motor MT2 is driven in step ST32, the control unit 120 returns the thrust plate 35 from the thrust position 35'' to the retracted position so as not to prevent the sheet from being caught in the nip portion 39 of the folding roller pair 34. A saving process is executed (step ST33) This saving process is performed in the same manner as described with reference to FIGS.

That is, in the state of FIG. 7(e), the control unit 120 reversely drives the thrust plate driving motor MT3 to move the thrust plate 35 from the thrust position 35″ horizontally toward the upstream side in the sheet conveying direction toward the retracted position. When the third detection sensor S3 below the first lower guide portion 46a detects the detection flag of the sliced plate 35 and turns on, the sliced plate drive motor MT3 is stopped. It is arranged at the retracted position as shown in FIG. 7(f).

At this time, the gap 48 between the first and second lower guide portions 46a, 46b is completely opened, and the second path portion of the central conveying path 42 is opened to the loop forming space 50 below. Therefore, the folding loop FL can be smoothly wound into the nip portion 39 of the folding roller pair 34 without being hindered by the veneer 35 continuously from the start of winding in FIG. 7(e).

The folding roller pair 34 continues to be rotationally driven even after the cutting board 35 is retracted. Therefore, as shown in FIG. 7(f), the sheet is folded in three (Z-fold) with the leading edge thereof and the second fold formed by the pair of folding rollers 34 facing forward, and then folded in three (Z-fold). They are nipped in pairs and transported downstream along the sheet transport path 43 .

As the sheet is conveyed in this way, the fold loop FL in the loop forming space 50 gradually becomes smaller. The folded loop FL enters the third path portion of the central transport path 42 and is squeezed from above and below by the second horizontal portion 45b of the upper transport guide 45 and the second inclined guide portion 52b of the second lower guide portion 46b. , a thin loop shape extending in the sheet conveying direction. Further, the folding loop FL advances between the second horizontal portion 45b and the second horizontal guide portion 52a of the second lower guide portion 46b, and folds from above and below at the folding position FP1 of the trailing end (upstream end) that serves as the first folding line. It is bent in half.

The folding position FP1 of the sheet is conveyed in the bent form in this manner without causing any slippage or displacement in the sheet conveying direction with respect to the upstream portion of the sheet superimposed thereon, and the folding roller pair 34 is pressurized and bent at the nip portion 39 of the . Therefore, the first fold line (202 in FIG. 4) is stably formed at a desired position on the sheet with high precision without causing variations as in the conventional art.

As a result, as shown in FIG. 4, a Z-folded sheet SH having a first fold line 202 for inward folding and a second fold line 203 for outward folding is generated. In the present embodiment, as described above, the folding roller pair 34 that is not rotating forms the folding loop FL while nipping the leading edge of the sheet, and then the folding roller pair 34 is rotated to , the leading end portion of the sheet that was nipped when the folding loop FL was formed is Z-folded so as to protrude from the second folding line toward the leading end side (downstream side).

Next, when the second detection sensor S2 in the sheet carry-in path 41 detects the trailing edge of the sheet being conveyed by the pair of registration rollers 33 and the pair of folding rollers 34 and turns off (Y in step ST34), the control unit 120 executes a guide process for moving the veneer 35 from the retracted position to the guide position 35' (step ST35). At this time, the folding loop FL is set to have already passed the folding roller pair 34 . Therefore, even if the sliced plate 35 is moved to the guide position 35', the conveyance of the sheet in the central conveyance path 42 and the crease formation processing by the folding roller pair 34 are not hindered.

The guide processing is executed, for example, according to the procedure shown in the flowchart of FIG. The sliced plate driving motor MT3 is driven forward (step ST56) to move the sliced plate 35 horizontally toward the folding roller pair 34 side. When the drive amount of the sliced plate drive motor MT3 reaches the preset fourth set drive amount (Y in step ST57), the sliced plate drive motor MT3 is stopped (step ST58).

Here, the fourth set drive amount is the drive amount of the sliced plate drive motor MT3 required to move the sliced plate 35 from the retracted position to the guide position 35'. As a result, the gap 48 between the first and second lower guide portions 46a and 46b is closed by the thrust plate 35, so that the trailing edge of the sheet is guided along the center conveying path 42 to the upper surface of the thrust plate 35, and is pushed by the folding rollers. It is transported straight towards pair 34 . The amount of rotation of the veneer drive motor MT3 can be the amount of rotation of the motor (the number of rotations of the rotary shaft, the rotation angle, the rotation time, etc.).

Next, in step ST34, when the second detection sensor S2 detects the trailing edge (upstream edge) of the sheet passing through the central conveying path 42 and turns off, the control unit 120 controls the folding roller driving motor MT2 from that point onwards. is counted, and when the preset stop driving amount is reached (Y in step ST36), the registration roller driving motor MT1 and the folding roller driving motor MT2 are stopped (step ST37).

Here, the predetermined stop driving amount is a driving amount of the folding roller driving motor MT2 sufficient for the trailing edge of the sheet to pass through the folding roller pair 34 . As a result, the registration roller pair 33 and folding roller pair 34 stop rotating without causing any trouble in conveying the sheet from the sheet exit 32b to the sheet post-processing apparatus B, and Z-folding of the sheet is completed.

As described above, the present invention has been described in relation to the preferred embodiments, but the present invention is not limited to the above embodiments, and can be implemented with various changes or modifications within its technical scope. Needless to say.

A image forming apparatus C sheet folding device 32 transport path 33 registration roller pair (transport roller pair)
34 folding roller pair 35 veneer (punching member)
39 nip portion 50 loop forming space 120a fold position adjusting means 120b hanging amount adjusting means 201 sheet leading edge 202 first fold 203 second fold

Claims (4)

a conveying roller for conveying the sheet in a predetermined conveying direction;
a folding roller pair that is arranged downstream of the transport roller in the transport direction and has a nip portion that nips a sheet to form a fold, and that can rotate forward and backward;
a conveying path along which the sheet conveyed by the conveying roller is conveyed from the conveying roller to the pair of folding rollers along the conveying direction;
a loop forming space formed below the conveying path so that the sheet hangs down from the conveying path on the upstream side of the pair of folding rollers in the conveying direction ;
a pushing member movable from the upstream side in the conveying direction toward a pushing position that pushes the sheet conveyed by the conveying roller and nips a predetermined position of the sheet with the pair of folding rollers;
When the leading portion in the carrying direction of the sheet conveyed by the carrying rollers in the feeding operation by forward rotation of the pair of folding rollers passes through the nip portion, the crease formation reference portion set in advance at the leading portion passes through the nip portion. folding position adjusting means for rotating the pair of folding rollers in reverse at a speed slower than the normal rotation speed of the pair of folding rollers in the feeding operation so as to be positioned at the nip portion;
The folding position adjusting means nips a predetermined position of the sheet pushed by the pushing member moved to the pushing position and the folding reference portion nipped at the nip portion, and folds the sheet. A sheet folding device, wherein a fold is formed at a predetermined position of the sheet by rotating the pair of rollers forward again. When the folding roller pair rotates in the same direction as the transport roller and the leading portion of the sheet transported by the transport roller passes through the nip portion , the rotational speed of the folding roller pair is set to the transport roller. 2. The sheet folding device according to claim 1, wherein the rotational speed of the sheet folding device is the same as that of the first. 3. The method according to claim 1, wherein the fold position adjusting means adjusts the amount of conveyance in the opposite direction due to the reverse rotation of the pair of folding rollers, based on the position of the fold forming reference portion in the conveying direction. A sheet folding device as described. an image forming apparatus for forming an image on a sheet;
4. The sheet folding device according to any one of claims 1 to 3, which folds a sheet sent from the image forming apparatus ;
An image forming system comprising:

Images