JP7746682B2 - Sheet processing apparatus and image forming apparatus - Google Patents

Description

This disclosure relates to sheet processing devices and image forming devices, and in particular to technology that prevents skew during sheet folding and improves the accuracy of the folding position during folding.

Sheet processing devices perform processes such as folding (such as folding in half or Z-folding) on printed materials output by an image forming device or sheets supplied from a tray, punching holes, and stapling.

Of these processes, folding, for example, is not necessarily performed every time the image forming apparatus outputs a printed material. Therefore, as shown in FIG. 22, a post-processing device has been disclosed that includes a conveying roller pair 2201, a folding roller pair 2203 that performs a first folding process for folding in half, a folding roller pair 2202 that performs a second folding process for Z-folding after the first folding process, and a guide member 2206 that prevents contact with the nip 22N3 of the folding roller pair 2203 (see Patent Document 1). This guide member 2206 is used to guide the leading edge of paper that is not to be folded or paper before the first fold is formed into the nip 22N2 of the folding roller pair 2202, preventing these from accidentally heading toward the folding roller pair 2203 and causing a paper jam, achieving good paper feed efficiency.

Furthermore, when performing folding processing, it is important to improve the accuracy of the folding position. For this reason, as shown in FIG. 23, a sheet folding device C has been disclosed that includes a conveyance path 2342 for conveying the sheet, a feed roller 2333, a pair of folding rollers 2334 arranged downstream of the feed roller 2333, a space 2350 provided below the conveyance path 2342 so as to allow the sheet to hang down from the conveyance path 2342 upstream of the pair of folding rollers 2334, a pushing member 2335 that can push against a predetermined position on the sheet hanging down into the space 2350 and move to a pushing position toward the pair of folding rollers 2334, and a guide unit 2345 that guides the conveyed sheet on the upstream side of the space 2350 in the conveyance direction (see Patent Document 2). The pushing member 2335 is positioned so as to push against the sheet hanging down into the space 2350 near the downstream end of the guide unit 2345 in the conveyance direction.

With this configuration, deviations and variations in the folding position can be reduced even if the degree of sagging (curvature) of the sheet varies depending on the rigidity and other characteristics of the sheet and the amount of feed from the feed roller 2333. This improves the positional accuracy of the folds formed on the sheet.

JP 2017-128411 A Japanese Patent Application Laid-Open No. 2020-093856

In the first of the above conventional technologies, the folding roller pair 2203 is disposed at a position separated from the conveying path 22TR1 midway from the conveying roller pair 2201 to the folding roller pair 2202, and an opening 2207a is provided in the paper guide 2207 that guides the sheet along the conveying path 22TR1 in order to transport the sheet for folding processing along the conveying path 22TR2 to the folding roller pair 2203.

By blocking the opening 2207a, the guide member 2206 prevents the sheet from moving toward the pair of folding rollers 2203. As a result, the sheet being transported along the transport path 22TR1 does not rub against the paper guide 2207 and the guide member 2206 in a consistent manner, which may cause the sheet to become skewed before reaching the pair of folding rollers 2202.

In addition, in the second prior art, in order to allow the sheet to droop into the space 2350 on the conveyance path 2342 from the feed roller 2333 to the folding roller pair 2334, the lower conveyance guide 2346 that guides the sheet along the conveyance path 2342 is divided into a first lower guide portion 2346a and a second lower guide portion 2346b. When the sheet is conveyed from the feed roller 2333 to the folding roller pair 2334, a pusher member 2335 advances between the first lower guide portion 2346a and the second lower guide portion 2346b to prevent the sheet from drooping into the space 2350.

Even in this case, the friction between the sheet and the lower conveying guide 2346 or the pusher member 2335 is not constant, so there is a risk that the sheet may become skewed before reaching the folding rollers 2334.

However, neither of these conventional technologies performs registration correction. Therefore, if the folding process is performed without correcting the sheet skew, the accuracy of the folding position will decrease.

On the other hand, if a registration loop space is provided on transport path 22TR1 or transport path 2342 to perform registration correction, there is a risk that part of the sheet will enter the registration loop space when it is transported to folding roller pair 2203 or space 2350 for folding. In this case, the length of the sheet that enters the registration loop space will not be constant, so even if the sheet skew can be corrected, the reduction in folding position accuracy cannot be eliminated.

This disclosure was made in consideration of the above-mentioned problems, and aims to provide a sheet processing device that can perform folding with high positional accuracy, and an image forming device equipped with the same.

To achieve the above object, a sheet processing apparatus according to one embodiment of the present disclosure comprises: a first pair of rollers that transports a sheet along a transport path; a second pair of rollers arranged downstream of the first pair of rollers in the sheet transport direction; a first space that receives a first loop portion of the sheet during registration correction when the second pair of rollers is stopped; a third pair of rollers that folds the sheet at a fold position downstream of the first pair of rollers and upstream of the second pair of rollers after registration correction; a second space that receives a second loop portion of the sheet formed during folding by the third pair of rollers; a shielding member that is movable between a shielding position that blocks the sheet from entering the first space and a retracted position that does not provide shielding; and control means that moves the shielding member to the retracted position during registration correction and to the shielding position during folding.

The sheet conveying device also includes a first pair of rollers that conveys the sheet along the conveying path, a second pair of rollers that is arranged downstream of the first pair of rollers in the sheet conveying direction and is used for registration correction, a third pair of rollers that is used for folding the sheet after registration correction, and a second space that receives the second loop portion of the sheet that bends toward the third pair of rollers during folding, wherein the second space also serves as the first space that receives the first loop portion of the sheet during registration correction, and further includes a shielding section that is movable between a shielding position that blocks the sheet from entering the second space and a retracted position that does not provide said shielding, and that guides the sheet to the second pair of rollers in the shielding position, and a control means that moves the shielding section to the shielding position during sheet conveyance and to the retracted position during registration correction and folding .

In this case, the device may include a second shielding member that can be moved between a shielding position that blocks the entry of sheets into the second space and a retracted position that does not provide such shielding, and a second control means that moves the second shielding member to the shielding position during registration correction and to the retracted position during folding processing.

Furthermore, the second shielding member may move in conjunction with the shielding member.

Furthermore, the shielding member may also serve as the second shielding member, and the control means may also serve as the second control means.

Furthermore, the second roller pair and the third roller pair may share one roller.

The second roller pair may also be used for a second folding process that is performed after the folding process using the third roller pair.

The first space may also be located on the opposite side of the conveying path from the second space.

The first space may also be located on the same side of the conveying path as the second space.

The registration correction may also be performed by having the first roller pair transport the sheet while the second roller pair is stopped from rotating, thereby forming a first loop portion in the sheet.

The folding process may also be performed by having the first roller pair transport the sheet faster than the second roller pair, causing the second loop portion formed in the sheet to bend toward the third roller pair.

Furthermore, prior to the sheet being bent, after the registration correction, the second roller pair may be rotated at a higher speed than the first roller pair, or the first roller pair may be stopped while the second roller pair is rotating, thereby eliminating the loop at the first loop location formed by the registration correction.

An image forming apparatus according to one embodiment of the present disclosure includes an image forming unit that forms an image on a sheet, and a sheet processing device according to one embodiment of the present disclosure, and the sheet processing device processes the sheet on which the image has been formed by the image forming unit.

In this way, a first space is provided to accommodate the looped portion of the sheet and perform registration correction, correcting the skew of the sheet and preventing the folding position of the sheet from becoming tilted. Furthermore, during folding, the sheet is shielded by a shielding member to prevent it from bending into the first space, stabilizing the amount of bending of the looped portion of the sheet into the second space and improving the accuracy of the folding position of the sheet.

1 is an external perspective view showing a main configuration of an image forming apparatus 1. FIG. FIG. 2 is an external perspective view showing the main components of the sheet processing unit 100. 1A and 1B are schematic diagrams illustrating the operating state of the sheet processing unit 100 when Z-folding a sheet S, where FIG. 1A shows the operating state during sheet conveyance, and FIG. 1B shows the operating state during registration correction. 10A and 10B are schematic diagrams illustrating the operating state of the sheet processing unit 100 when folding a sheet S in a Z-shape, where (a) shows the operation of shielding the resist loop space 341 during the first fold, and (b) shows the operation of forming a first fold loop 392 in the sheet S during the first fold. 10A and 10B are schematic diagrams illustrating the operating state of the sheet processing unit 100 when Z-folding the sheet S, where (a) shows the operation of sandwiching the first folding loop 392 in the folding nip 332 of the folding roller pair 330 during the first folding, and (b) shows the operation of forming the second folding loop during the second folding. 10A and 10B are schematic diagrams illustrating the operating state of the sheet processing unit 100 when Z-folding the sheet S, where (a) shows the operation of clamping the second fold loop 393 in the resist nip 323 of the resist roller pair 320 during the second fold, and (b) shows the state after the Z-folding is completed. FIG. 2 is a block diagram showing the main configuration of a sheet processing control unit 103 of the sheet processing unit 100. 10 is a flowchart illustrating the operation of a sheet processing control unit 103 when Z-folding a sheet S is performed. 10A and 10B are schematic diagrams illustrating the operating state of a sheet folding unit 200 according to a modified example in which a registration loop space 341 is provided on the same side of the conveying path 370 as the folding loop 393, where (a) shows the operating state during sheet conveyance, and (b) shows the operating state during registration correction. This is a schematic diagram illustrating the operating state of a sheet folding unit 200 relating to a modified example in which the resist loop space 341 is provided on the same side of the conveying path 370 as the folding loop 393, and shows the operation of forming the first folding loop 392 on the sheet S with the resist loop space 341 shielded during the first folding. 10A and 10B are schematic diagrams illustrating the operating state of a modified sheet folding unit 200 that is provided with a guide member 1100 that shields the folding loop space 342, where (a) shows the operating state in which the guide portion 1101 of the guide member 1100 shields the folding loop space 342 during sheet transport, and (b) shows the operating state in which the guide portion 1101 of the guide member 1100 shields the folding loop space 342 during registration correction. This is a schematic diagram illustrating the operating state of a modified sheet folding unit 200 that is provided with a guide member 1100 that shields the folding loop space 342, and shows the operation of forming a first folding loop 392 in the sheet S with the folding loop space 342 open during the first folding. 10A and 10B are schematic diagrams illustrating the operating state of a modified sheet folding unit 200 in which a stopper 1300 is fixed to a guide member 1100 that shields the folding loop space 342, where (a) shows the operating state in which the guide portion 1101 of the guide member 1100 shields the folding loop space 342 during sheet transport, and (b) shows the operating state in which the guide portion 1101 of the guide member 1100 shields the folding loop space 342 during registration correction. This is a schematic diagram illustrating the operating state of a modified sheet folding unit 200 in which a stopper 1300 is fixed to a guide member 1100 that shields the folding loop space 342, and shows the operation of forming a first folding loop 392 in a sheet S with the shielding member 300 that shields the register loop space 341 fixed in the shielding position by the stopper 1300 during the first folding. 10A and 10B are schematic diagrams illustrating the operating state of a modified sheet folding unit 200 that uses a shielding member 1500 that moves between a shielding position and a retracted position using a rack and pinion mechanism, where (a) shows the operating state in which the shielding portion 1501 of the shielding member 1500 shields the folding loop space 342 during sheet transport, and (b) shows the operating state during registration correction. This is a schematic diagram illustrating the operating state of a modified sheet folding unit 200 that uses a shielding member 1500 that moves between a shielding position and a retracted position using a rack and pinion mechanism, and shows the operation of forming a first folding loop 392 in the sheet S when the resist loop space 911 is shielded by the shielding portion 1501 of the shielding member 1500 during the first folding. 10A and 10B are schematic diagrams illustrating the operating state of a sheet folding unit 200 according to a modified example in which a loop space 1706 serves as both a registration loop space and a folding loop space, in which (a) shows the operation of the shielding member 1700 shielding the loop space 1706 during sheet transport, and (b) shows the operation of the shielding member 1700 retracting so that the registration loop 391 of the sheet S can be vented into the loop space 1706 during registration correction. This is a schematic diagram illustrating the operating state of a sheet folding unit 200 according to a modified example in which the loop space 1706 serves as both a registration loop space and a folding loop space, and shows the operation of projecting the folding loop 393 of the sheet S into the loop space 1706 during the first folding operation with the shielding member 1700 retracted. A schematic diagram illustrating the operating state of a sheet folding unit 200 relating to a modified example that does not use a shielding member, where (a) shows the operation during sheet transport, and (b) shows the operation of projecting the registration loop 391 of the sheet S into the loop space 1903 during registration correction. 19A and 19B are schematic diagrams illustrating the operating state of the sheet folding unit 200 according to a modified example in which a shielding member is not used, and illustrate the operation of projecting the folding loop 392 of the sheet S into the loop space 1903 during the first folding. 10 is a schematic diagram showing the main configuration of a sheet folding unit 200 in which a pair of registration rollers 320 and a pair of folding rollers 330 do not share a roller. FIG. FIG. 1 is a schematic diagram showing the main configuration of a post-processing device according to a conventional technique. FIG. 1 is a schematic diagram showing a main configuration of a sheet folding device according to a conventional technique.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a sheet processing apparatus and an image forming apparatus according to the present disclosure will be described with reference to the accompanying drawings.
[1] Configuration of Image Forming Apparatus First, the configuration of the image forming apparatus according to this embodiment will be described.

As shown in FIG. 1, image forming device 1 is a multi-function peripheral (MFP) that combines printing, copying, facsimile, and other functions, and includes an image reading unit 110, an image forming unit 120, a paper feed unit 130, an operation panel 140, and a sheet processing unit 100. Image reading unit 110 can read documents using the so-called sheet-through method and platen-set method to generate image data. Image forming unit 120 forms images using image data generated by image reading unit 110 or image data specified in an image formation job received from another device (e.g., a personal computer) via a communication network (not shown), such as a LAN (Local Area Network) or the Internet.

The paper feed unit 130 supplies recording sheets that the image forming unit 120 uses to form images. The operation panel 140 presents information to the user of the image forming apparatus 1 and accepts operation input from the user. This operation input includes specifying whether or not sheet processing by the sheet processing unit 100 is required. If sheet processing by the sheet processing unit 100 is not required, the image forming unit 120 ejects the recording sheet on which the image has been formed onto the paper output tray 122. If sheet processing is required, the image forming unit 120 transports the recording sheet on which the image has been formed to the sheet processing unit 100.

The image forming unit 120 is equipped with a main body control unit 121, which monitors and controls the operation of each unit of the image forming device 1. When the user's operation input received by the operation panel 140 is a sheet processing instruction, the main body control unit 121 notifies the sheet processing unit 100 of the content of the user instruction before transporting the recording sheet to the sheet processing unit 100.

The sheet processing unit 100 receives recording sheets from the image forming unit 120 and processes them. As shown in FIG. 2, the sheet processing unit 100 includes a sheet folding unit 200, a sheet sensor 201, and a stapler unit 210. The sheet folding unit 200 folds the sheets conveyed from the image forming unit 120. The sheet sensor 201 detects the recording sheets fed from the image forming unit 120.

The stapler unit 210 also staples sheets conveyed from the image forming unit 120. The sheet processing unit 100 may also perform sheet processing other than folding and stapling, such as punching. The sheet processing unit 100 ejects processed sheets onto the paper output trays 101 and 102.

The sheet processing unit 100 also includes a sheet processing control unit 103. The sheet processing control unit 103 monitors and controls the operation of each unit of the sheet processing unit 100. The sheet processing unit 100 also receives a notification of a user instruction received by the main body control unit 121 of the image forming unit 120 from the operation panel 140. This notification includes, for example, the type of sheet processing specified by the user, and the sheet processing unit 100 executes the specified type of sheet processing.
[2] Sheet processing unit 100
Next, the operation of the sheet processing section 100, particularly the operation of the sheet folding unit 200, will be described using Z-folding of a sheet as an example.

As shown in FIG. 3(a), the sheet folding unit 200 includes a pair of transport rollers 310, a pair of registration rollers 320, and a pair of folding rollers 330. The pair of transport rollers 310 is composed of transport rollers 311 and 312. When the sheet sensor 201 detects the sheet S fed from the image forming unit 120, the rotation of the transport roller 311 begins, and the transport roller 312 rotates in response to the rotation of the transport roller 311. As a result, the sheet S is transported in the direction of arrow C along the transport path 370.

The sheet folding unit 200 is equipped with a transport motor 381 that rotates and drives the transport roller 311. Furthermore, a transport clutch 382 transmits the rotational driving force generated by the transport motor 381 to the transport roller 311, or blocks the transmission of the rotational driving force to the transport roller 311. The transport motor 381 and the transport clutch 382 operate under the control of the sheet processing control unit 103.

The registration roller pair 320 is composed of a shared roller 321 and a registration roller 322 that are shared with the folding roller pair 330, and is used for registration correction (skew correction) in addition to transporting the sheet S. The folding roller pair 330 is composed of a shared roller 321 and a folding roller 331, and is used for folding the sheet S.

The sheet folding unit 200 is equipped with a shared motor 383 that drives the shared roller 321 to rotate. When the shared motor 383 drives the shared roller 321 to rotate, the registration roller 322 and folding roller 331 rotate in response to the rotation of the shared roller 321. The shared motor 383 operates under the control of the sheet processing control unit 103.

The transport guide members 351, 352, 353, and 354 guide the sheet along the transport path 370 from the transport roller pair 310 to the registration roller pair 320.

A registration loop space 341 is provided on the transport path 370 from the transport roller pair 310 to the registration roller pair 320 to allow the loop portion (registration loop) 391 (Figure 3(b)) of the sheet S to be bent out when performing registration correction on the sheet S.

The shielding member 300 can swing up and down at its upstream end in the sheet transport direction, with a swing shaft 301 located at its downstream end in the sheet transport direction as the swing center. Under the control of the sheet processing control unit 103, the shielding member 300 swings in response to swing drive from the shielding member drive motor 384, and can move back and forth between a shielding position (Figure 3(a)) where it blocks the sheet S from entering the registration loop space 341, and a retracted position (Figure 3(b)) where it does not block the sheet S from entering the registration loop space 341.

When the sheet S is folded, a loop portion (first fold loop) 392 (Figure 4(b)) of the sheet S protrudes into the fold loop space 342, which is the space from the conveyance path 370 of the sheet S to the folding nip 332 of the folding roller pair 330. The folding process is performed by sandwiching the first fold loop 392 in the folding nip 332 of the folding roller pair 330. When folding the sheet S in a Z-shape, this folding process is the first folding process.

A sheet sensor 361 is disposed between the pair of transport rollers 310 and the pair of registration rollers 320 on the transport path 370 of the sheet S, and is capable of detecting the leading and trailing edges of the sheet S. Furthermore, a sheet sensor 362 is disposed downstream of the pair of registration rollers 320 on the transport path 370, and is also capable of detecting the leading and trailing edges of the sheet S. The sheet sensors 201, 361, and 362 may detect the sheet S optically or mechanically, and it goes without saying that the detection method is not limited.

As shown in FIG. 3(b), during registration correction of sheet S, the transport roller pair 310 transports sheet S, and the leading edge of sheet S is abutted against the registration nip 323 of the stopped registration roller pair 320, forming a registration loop 391. In this case, because the shielding member 300 is retracted to the retracted position, the registration loop 391 of sheet S bends toward the registration loop space 341. In this way, the skew of sheet S is corrected, and the folding position of sheet S can be prevented from tilting compared to when registration correction is not performed. In this sense, the accuracy of the folding position of sheet S can be improved.

When folding the sheet S after the registration correction, as shown in FIG. 4(a), the registration roller pair 320 is driven to rotate and transport the sheet S along the transport path 370. The registration roller pair 320 shares a common roller 321 with the folding roller pair 330, and the folding roller 331 also rotates in the direction of arrow H following the rotation of the common roller 321.

The sheet processing control unit 103 disengages the conveying clutch 382. In this way, the conveying roller pair 310 does not convey the sheet S, and as the registration roller pair 320 conveys the sheet S, the registration loop 391 of the sheet S is gradually eliminated. After the registration loop 391 of the sheet S is completely eliminated, the conveying roller pair 310 rotates in response to the sheet S.

When the sheet sensor 362 detects the leading edge of the sheet S, the sheet processing control unit 103 stops the rotation of the registration roller pair 320 and swings the shielding member 300 in the direction of arrow E toward the shielding position. This prevents the sheet S from entering the registration loop space 341 when forming the first fold loop 392, thereby improving the accuracy of the folding position of the sheet S compared to when the sheet S can enter the registration loop space 341.

In addition, the conveying speed of the conveying roller pair 310 may be slowed to a speed at which the registration loop 391 can be eliminated without disengaging the conveying clutch 382. Alternatively, the conveying roller pair 310 may continue to convey the sheet S at the original speed. When a fold loop 392 is formed during folding, the shielding member 300 is moved to the shielding position to prevent the registration loop 391 from entering the registration loop space 341, and the registration loop 391 is absorbed by the fold loop 392.

Next, as shown in FIG. 4(b), the sheet processing control unit 103 rotates the conveying roller pair 310 to convey the sheet S, causing the first folding loop 392 of the sheet S to bend toward the folding nip 332 of the folding roller pair 330 within the folding loop space 342. When the leading edge of the first folding loop 392 of the sheet S in the bending direction is pressed against the common roller 321 and the folding roller 331, the sheet processing control unit 103 rotates the folding roller pair 330 to sandwich the first folding loop 392 of the sheet S in the folding nip 332, thereby folding the sheet S in half so that the leading edge forms a crease.

The folding roller pair 330 continues to rotate, transporting the sheet S that has been folded the first time in the direction of arrow L, as shown in Figure 5(a). When the sheet S has been transported the transport amount corresponding to the second folding position, the sheet processing control unit 103 stops the rotational driving of the folding roller pair 330. The sheet processing control unit 103 then starts the rotational driving of the transport roller pair 310, causing the sheet S to be transported along the transport path.

As a result, a loop portion (second fold loop) 393 is formed in the sheet S, as shown in FIG. 5(b). As the transport roller pair 310 transports the sheet S, the second fold loop 393 protrudes toward the registration nip 323 of the registration roller pair 320 within the fold loop space 342. The second fold loop 393 of the sheet S is ultimately pressed against the shared roller 321 and the registration roller 321.

When the sheet processing control unit 103 rotates the pair of registration rollers 320 while the second folding loop 393 is pressed against the shared roller 321 and the registration roller 321, the second folding loop 393 is sandwiched in the registration nip 323, folding the sheet S, as shown in FIG. 6(a). At this time, the leading edge of the sheet S also passes through the registration nip 323.

Concurrently, a portion 394 of the sheet S folded in the first process is conveyed in the direction of arrow M by the pair of folding rollers 330, passes through the folding nip 332, and heads toward the registration nip 323. As shown in Figure 6(b) , the portion 394 folded in the first folding process that has passed through the registration nip 323 is further conveyed in the direction of arrow N. The sheet S is conveyed in the direction of arrow N, and finally, the trailing edge of the sheet S leaves the registration nip 323, completing the Z-folding of the sheet S.
[3] Configuration of Sheet Processing Control Unit 103 Next, the configuration of the sheet processing control unit 103 will be described.

As shown in FIG. 7, the sheet processing control unit 103 includes a CPU (Central Processing Unit) 701, a ROM (Read Only Memory) 702, a RAM (Random Access Memory) 703, and a timer 704. The CPU 701, ROM 702, RAM 703, and timer 704 are connected via an internal bus 705 so that they can exchange data with each other.

When the image forming apparatus 1 is reset, for example when power is turned on, the CPU 701 reads and starts up a boot program from the ROM 702, and executes the control program read from the ROM 702, using the RAM 703 as a working storage area. Furthermore, when executing the control program, the CPU 701 sets a time in the timer 704 and receives notification when the set time has elapsed.

By executing the control program, the CPU 701 controls the operation of the transport motor 381, transport clutch 382, shared motor 383, and shielding member drive motor 384, sets the timer 704, and references the detection signals of the sheet sensors 201, 312, and 313.

The sheet processing control unit 103 is also connected to the main body control unit 121, and receives instruction commands and notifications from the main body control unit 121, and notifies the main body control unit 121 of the status of the sheet processing unit 100. The main body control unit 121 monitors and controls the operations of the image reading unit 110, the image forming unit 120, the paper feeding unit 130, and the operation panel 140.
[4] Operation of the Sheet Processing Control Unit 103 The operation of the sheet processing control unit 103 will be described using the operation during Z-folding as an example. It is assumed that the sheet processing control unit 103 has received an instruction to perform Z-folding on the sheet from the main body control unit 121 of the image forming apparatus 1 in advance.

As shown in FIG. 8, when the sheet sensor 201 detects the leading edge of the sheet and thus detects that a sheet has been conveyed from the image forming unit 120 (S801: YES), the sheet processing control unit 103 starts driving the conveyance motor 381 (S802) and engages the conveyance clutch 382 (S803). This rotates the conveyance roller pair 310, and the sheet received from the image forming unit 120 is conveyed. Note that the time T1 is preset to a time appropriate for forming a registration loop 391 with the loop amount required for registration correction.

Next, when the sheet sensor 361 detects the leading edge of the sheet (S811: YES), the sheet processing control unit 103 drives the shielding member drive motor 384 to swing the shielding member 300 to the retracted position (S812) and sets the timer 704 to time T1. By transporting the sheet S with the transport roller pair 310 for time T1, a registration loop 391 is formed in the sheet S, and the skew is corrected.

If a timeout occurs in the timer 704 (S821: YES), the transport clutch 382 is disengaged (S822), the transmission of rotational drive force from the transport motor 381 to the transport roller 311 is stopped, and the rotational drive of the transport motor 381 is stopped (S823). Then, the forward rotation drive of the shared motor 383 is started (S824). This causes the shared roller 321 to rotate forward in the direction of arrow G shown in Figure 4(a), and the sheet S is transported toward the sheet sensor 362.

When the sheet sensor 362 detects the leading edge of the sheet S (S831: YES), the rotation of the shared motor 383 is stopped (S832). This causes the sheet S to be sandwiched in the registration nip 323 of the registration roller pair 320. Next, the shielding member drive motor 384 is driven to swing the shielding member 300 from the retracted position to the shielding position (S833), and the timer 704 is set to time T2.

Time T2 is preset to the time required for the first fold loop 392 of sheet S to come into contact with the folding roller pair 330 and for the folding roller pair 330 to rotate and for the first fold loop 392 of sheet S to be sandwiched in the folding nip 332.

Then, the conveying motor 381 starts to be driven (S834) and the conveying clutch 382 is engaged (S835). As a result, when the sheet S is conveyed by the conveying roller pair 310 for time T2, a first folding loop 392 is formed in the sheet S, which bends toward the folding nip 332 of the folding roller pair 330 and comes into contact with the shared roller 321 and the folding roller 331.

If a timeout occurs in the timer 704 (S841: YES), the conveying clutch 382 is disengaged (S842) and the rotation of the conveying motor 381 is stopped (S843). This stops the first folding loop 392 of the sheet S from entering the folding nip 332 of the folding roller pair 330. Next, the timer 704 is set to time T3 (S844).

Time T3 is set to match the second folding position of sheet S. Then, the shared motor 383 starts to rotate in reverse (S845). This causes the shared roller 321 to rotate in the reverse direction of arrow J, and the first folding loop 392 of sheet S is sandwiched between the folding nip 332 of the folding roller pair 330, performing the first folding.

If a timeout occurs in the timer 704 (S851: YES), the reverse rotation of the shared motor 383 is stopped (S852). Then, the rotation of the conveying motor 381 is started (S853), the conveying clutch 382 is engaged (S854), and the timer 704 is set to time T4 (S855). As the conveying roller pair 310 conveys the sheet S for time T4, a second fold loop 393 is formed in the sheet S, which then bends toward the registration nip 323 of the registration roller pair 320 and comes into contact with the shared roller 321 and the registration roller 321.

If the timer 704 times out (S861: YES), the conveying clutch 382 is disengaged (S862), and the rotational drive of the conveying motor 381 is stopped (S863). Then, the forward rotational drive of the shared motor 383 is started (S864). This causes the second folding loop 393 of the sheet S to be sandwiched in the registration nip 323 of the registration roller pair 320, and the second folding is performed.

After that, when the sheet sensor 362 detects the rear end of the sheet S (S871: YES), the forward rotation of the shared motor 383 is stopped (S872).

In this way, even when a registration correction is performed on the sheet S to prevent the folding direction of the sheet S from tilting, the shielding member 300 blocks the sheet S from entering the registration loop space 341 when forming the first folding loop 392 and the second folding loop 393, thereby improving the positional accuracy of the first and second folds.
[5] Modifications The present disclosure has been described above based on the embodiments, but it goes without saying that the present disclosure is not limited to the above-described embodiments, and the following modifications may be implemented. Note that in this specification, common components are assigned common reference numerals.
(5-1) In the above embodiment, the example was described in which the resist loop space 341 and the fold loop space 342 are located on opposite sides of the conveying path 370. However, it goes without saying that the present disclosure is not limited to this, and instead, the resist loop space 341 and the fold loop space 342 may be located on the same side of the conveying path 370.

With this configuration, when sheet S is being transported, as shown in Figure 9(a), the shielding member 901 moves to the closed position, preventing sheet S from entering the registration loop space 911. Furthermore, when registration correction is performed, as shown in Figure 9(b), the shielding member 901 swings in the direction of arrow O around the swing shaft 902 as the swing center, moving to the retracted position, allowing the registration loop 921 of sheet S to enter the registration loop space 911.

10, during the first folding, the shielding member 901 swings in the direction of arrow P around the swing shaft 902 to move to the shielding position, preventing the resist loop 921 of the sheet S from entering the resist loop space 911. In this way, the accuracy of the folding position can be improved, as in the above embodiment.
(5-2) In the above embodiment, an example was given in which a shielding member 300 was used to prevent the sheet S from entering the resist loop space 341, but it goes without saying that the present disclosure is not limited to this, and in addition, the following may also be done.

That is, to prevent the sheet S from entering the fold loop space 342 when the leading edge of the sheet S is conveyed to the registration nip 323 of the registration roller pair 320, a guide member 1100 may be provided to guide the sheet S to the registration nip 323, as shown in Figures 11 and 12. The guide member 1100 is composed of a guide portion 1101, an arm portion 1102, and a swing shaft 1103, and can swing in the direction of arrow Q around the swing shaft 1103 as the swing center.

When a sheet is being conveyed, as shown in Figure 11(a), the guide portion 1101 moves to the blocking position. This blocks the gap between the conveying path 370 and the fold loop space 342 to prevent the sheet S from deviating from the conveying path 370 and entering the fold loop space 342. As shown in Figure 11(b), even during registration correction, the guide portion 1101 remains in the blocking position to prevent the sheet S from entering the fold loop space 342.

On the other hand, as shown in FIG. 12, during the first fold, the guide member 1100 swings in the direction of arrow Q around the swing shaft 1103, causing the guide portion 1101 to move from the shielding position to the retracted position. This allows the first fold loop 392 of the sheet S to be projected from the conveying path 370 into the fold loop space 342. Also, during the second fold, the guide portion 1101 remains in the retracted position, allowing the second fold loop 393 of the sheet S to be projected from the conveying path 370 into the fold loop space 342.

In this way, the leading edge of the sheet S can be reliably conveyed to the registration nip 323, and it is possible to prevent the leading edge of the sheet S from entering the fold loop space 342 and causing a paper jam or the like.
(5-3) In the above embodiment, an example was described in which the shielding member 300 is oscillated using the shielding member drive motor 384. However, it goes without saying that the present disclosure is not limited to this. Alternatively, the shielding member drive motor 384 may be omitted as follows.

As shown in Figure 13(a), when a sheet is being conveyed, the shielding member 300 is pivotally supported by a swing shaft 301, and when not subjected to external force, it is positioned in the shielding position due to its own weight. Furthermore, the guide portion 1101 of the guide member 1100 is also in the shielding position, preventing the sheet S from entering the fold loop space 342 and guiding it to the registration nip 323.

As shown in Figure 13(b), during registration correction, the registration loop 391 formed on the sheet S pushes it up, causing it to swing and move to the retracted position. In this case, the guide portion 1101 of the guide member 1100 remains in the blocking position, blocking the sheet S from entering the fold loop space 342.

As shown in Figure 14, during the first fold, a drive unit (not shown) drives the guide member 1100 to swing, causing the guide member 1100 to swing in the direction of arrow Q. A stopper 1300 is fixed to the guide member 1100. In addition, a rib 302 is provided on the shielding member 300. When the guide member 1100 swings in the direction of arrow Q and the guide portion 1101 moves to the retracted position, the end face 1301 of the stopper 1300 abuts against the rib 302 of the shielding member 300, preventing the shielding member 300 from swinging.

This allows the shielding member 300 to remain in the shielding position, preventing the sheet S from entering the registration loop space 341 during the first folding. This improves the accuracy of the folding position during the first folding. Furthermore, since the shielding member drive motor 384 is no longer necessary, the component costs and assembly costs of the sheet processing unit 100 can be reduced, and the sheet processing unit 100 can be made smaller and more space-saving.
(5-4) Regarding a configuration in which the resist loop space 911 and the folding loop space 342 are on the same side of the conveying path 370, the above modified example has been described using an example in which the shielding member 901 is swung between the shielding position and the retracted position, but it goes without saying that the present disclosure is not limited to this, and instead, the following may be used.

That is, as shown in Figures 15 and 16, the shielding member 1500 has a rack and pinion configuration, and a rack portion 1502 is provided on the shielding portion 1501, which also serves as a guide member that guides the sheet S along the transport path 370, and meshes with a pinion gear 1503. The pinion gear 1503 is rotated by a shielding member drive motor 1510, which causes the shielding portion 1501 to move parallel to the transport path 370.

As shown in Figure 15(a), when a sheet is being conveyed, the shielding portion 1501 shields the fold loop space 342 and guides the leading edge of the sheet S to the registration nip 323 of the registration roller pair 320. This prevents the sheet S from entering the fold loop space 342, thereby preventing paper jams and other problems. In this case, the registration loop space 341 is not shielded.

As shown in Figure 15(b), during registration correction, the shielding portion 1501 shields the fold loop space 342 and maintains an unshielded state for the registration loop space 911. This causes the registration loop 1521 of the sheet S to protrude into the registration loop space 911, thereby correcting the skew of the sheet S.

As shown in Figure 16, during the first fold, the shielding member drive motor 1510 rotates the pinion gear 1503 in the direction of arrow R, causing the shielding portion 1501 to move in the direction of arrow T. This unblocks the fold loop space 342, opening the fold loop space 342 while shielding the registration loop space 911.

Before the shielding portion 1501 is moved in the direction of arrow T, the pair of registration rollers 320 transports the sheet S, causing the leading edge of the sheet S to advance to the detection position of the sheet sensor 362, thereby eliminating the registration loop 1521 of the sheet S. Therefore, the registration loop 1521 of the sheet S is not pinched by the shielding portion 1501.

After the shielding portion 1501 opens the fold loop space 342, the conveying roller pair 310 conveys the sheet S, forming a fold loop 1522 in the sheet S, which then curves toward the folding nip 332 of the folding roller pair 330.

Even in this case, the shielding portion 1501 shields the register loop space 911 so that the register loop 1521 is not formed in the sheet S during folding processing, thereby improving the accuracy of the folding position of the sheet S. Furthermore, since the shielding member 1500 is moved along the conveying path 370 without swinging, only a small space is required to shield the register loop space 911. Therefore, it becomes easy to reduce the size of the sheet processing portion 100.
(5-5) In the above embodiment, the example was described in which the resist loop space 341 and the fold loop space 342 are provided separately, but it goes without saying that the present disclosure is not limited to this, and instead, at least a portion of the resist loop space 341 and the fold loop space 342 may be shared.

Taking the example of a case where the registration loop space 341 also serves as the folding loop space 342, as shown in Figure 17(a), the sheet folding unit 200 of this modified example is equipped with a transport roller pair 310 and guide members 1701 and 1702, and the sheet fed using the transport roller pair 310 is guided in the direction of arrow C using the guide members 1701 and 1702. Because the guide members 1701 and 1702 are adjacent to each other across the transport path of the sheet S, there is not enough space within the space between the guide members 1701 and 1702 to form the registration loop required for registration correction. The downstream end of the guide member 1702 in the sheet transport direction is just before the loop space 1706.

The shielding member 1700 has a rack and pinion configuration, with a rack portion 1704 provided on the shielding portion 1703, which also serves as a guide member for guiding the sheet S in the direction of arrow C, and meshing with a pinion gear 1705. The pinion gear 1705 is driven to rotate by a shielding member drive motor 1710, which causes the shielding portion 1703 to move parallel to the direction of arrow C.

The shielding portion 1703 can move between a shielding position where it advances between the transport path of the sheet S and the loop space 1706 to prevent the sheet from entering the loop space 1706, and a retracted position where it retreats from between the transport path of the sheet S and the loop space 1706 and releases the shielding. When the sheet is being transported, the shielding portion 1703 advances to the shielding position and guides the leading edge of the sheet S to the registration nip 323 of the registration roller pair 320.

During registration correction, as shown in FIG. 17(b), the shielding portion 1703 retracts from the shielding position to the retracted position, allowing the registration loop 391 of the sheet S to protrude toward the loop space 1706. This corrects the skew of the sheet S. Therefore, it is possible to prevent the first folding position of the sheet S from being tilted.

18 , during the first folding, the shielding portion 1703 remains in the retracted position, allowing the folding loop 392 of the sheet S to bend toward the loop space 1706. This allows the first folding process of the sheet S to be performed. Furthermore, since the loop space 1706 serves as both the registration loop space and the folding loop space, and there is no space other than the loop space 1706 where the sheet S can form a loop, the accuracy of the first folding position can be improved.
(5-6) In the above modified example, an example was given in which a shielding member 1700 is provided in a configuration in which the loop space 1706 serves as both a resist loop space and a folding loop space. However, it goes without saying that the present disclosure is not limited to this, and the following may be used instead.

That is, as shown in FIG. 19(a), the shielding member 1700 may be omitted from the sheet folding unit 200. During sheet transport, the leading edge of the sheet S sent out by the transport roller pair 310 is guided by guide members 1901 and 1902 to the registration nip 323 of the registration roller pair 320, in the same manner as in the above embodiment.

During registration correction, as shown in FIG. 19(b), the registration loop 391 of the sheet S is bent into the loop space 1903, thereby correcting the skew of the sheet S. During the first folding, as shown in FIG. 20, the folding loop 392 of the sheet S is bent into the loop space 903, thereby performing the first folding process of the sheet S.

In this way, the shielding member drive motor 1710 can also be omitted, so that the sheet processing section 100 can be made smaller, more space-saving, and less expensive.
(5-7) In the above embodiment, the example was described in which the registration roller pair 320 and the folding roller pair 330 share the shared roller 321. However, it goes without saying that the present disclosure is not limited to this, and the following may be used instead.

That is, as shown in FIG. 21, the registration roller pair 320 and the folding roller pair 330 do not need to share a roller. In this case, it is desirable to provide a guide member 2103 to prevent the sheet S from getting caught between the roller 2101 of the registration roller pair 320 and the roller 2102 of the folding roller pair 330 that faces this roller 2101.

Also, Figure 21 shows a case where the folding roller pair 330 is arranged below the transport path of the sheet S, but depending on the device configuration of the sheet processing unit 100, there may be more space above the transport path of the sheet S than below, and in such cases, the folding roller pair 330 may be arranged above the transport path.
(5-8) In the above embodiment, the image reading unit 110, the image forming unit 120, and the paper feeding unit 130 constitute a multifunction device. However, it goes without saying that the present disclosure is not limited to this. Even single-function devices such as printer devices, copy devices with scanners, and facsimile devices with facsimile communication capabilities can obtain the above-described effects by applying the present disclosure when combined with the sheet processing unit 100.

The sheet processing apparatus and image forming apparatus disclosed herein are useful as devices that can perform folding processes with high positional accuracy.

1.................................................................................Image forming apparatus 100...................................................................................Sheet processing section 110...................................................................................Image reading section 120...................................................................................Image forming section 130...................................................................................Paper feeding section 200...................................................................................Sheet folding unit 300, 901, 1500, 1700...Shielding member 310........................................................................................Pair of transport rollers 320........................................................................................Pair of registration rollers 330...........................................................................................Pair of folding rollers 341, 911...................................................................................Registration loop space 342...........................................................................................Folding loop space 391...................................................................................................Registration loop 392...................................................................................................Folding loop 1100...................................................................................Guide member 1300...................................................................................................Stopper 1706, 1903...................................................................................Loop space

Claims (13)

a first roller pair that transports the sheet along a transport path;
a second roller pair disposed downstream of the first roller pair in the sheet conveying direction;
a first space for receiving a first loop portion of the sheet during registration correction with the second roller pair stopped;
a third roller pair for folding the sheet at a folding position downstream of the first roller pair and upstream of the second roller pair after the registration correction;
a second space for receiving a second loop portion of the sheet formed for folding by the third roller pair;
a shielding member that is movable between a shielding position that shields the sheet from entering the first space and a retracted position that does not shield the sheet;
A sheet processing apparatus comprising: a control unit that moves the shielding member to a retracted position during registration correction and to a shielding position during folding processing. a first roller pair that transports the sheet along a transport path;
a second roller pair disposed downstream of the first roller pair in the sheet conveying direction and used for registration correction;
a third roller pair used for folding the sheet after the registration correction;
a second space for receiving a second loop portion of the sheet that curves toward the third roller pair during folding processing ;
The second space also serves as a first space for receiving the first loop portion of the sheet during registration correction,
moreover,
a shielding portion that is movable between a shielding position that shields the sheet from entering the second space and a retracted position that does not shield the sheet, and that guides the sheet to the second roller pair at the shielding position;
and a control means for moving the shielding portion to a shielding position during sheet conveyance and to a retracted position during registration correction and folding processing.
A sheet processing apparatus characterized by: a second shielding member that is movable between a shielding position that shields the sheet from entering the second space and a retracted position that does not shield the sheet;
2. The sheet processing apparatus according to claim 1, further comprising: second control means for moving the second shielding member to a shielding position during registration correction and to a retracted position during folding processing. 4. The sheet processing apparatus according to claim 3, wherein the second shielding member moves in conjunction with the first shielding member. the shielding member also serves as the second shielding member,
4. The sheet processing apparatus according to claim 3, wherein the control means also serves as the second control means. 6. The sheet processing apparatus according to claim 1, wherein the second roller pair and the third roller pair share one roller. 7. The sheet processing apparatus according to claim 1, wherein the second pair of rollers is used for a second folding process that is performed after the folding process using the third pair of rollers. 6. The sheet processing apparatus according to claim 1, wherein the first space is located on the opposite side of the conveying path from the second space. 8. The sheet processing apparatus according to claim 1, wherein the first space is located on the same side as the second space with respect to the transport path. 10. The sheet processing apparatus according to claim 1, wherein the registration correction is performed by causing the first roller pair to transport the sheet while the second roller pair is stopped from rotating, thereby forming a first loop portion in the sheet. 11. The sheet processing device according to claim 1, wherein the folding process is performed by the first roller pair transporting the sheet faster than the second roller pair, causing the second loop portion formed in the sheet to bend toward the third roller pair. The sheet processing apparatus according to claim 11, characterized in that, prior to the sheet being bent, after the registration correction, the second roller pair is rotated at a higher speed than the first roller pair, or the first roller pair is stopped while the second roller pair is rotated, thereby eliminating the loop at the first loop location formed by the registration correction. an image forming unit that forms an image on a sheet;
a sheet processing apparatus according to any one of claims 1 to 12,
The image forming apparatus is characterized in that the sheet processing apparatus processes sheets on which images have been formed in an image forming section.