Sheet processing apparatus, image forming system, and sheet folding method

The present application claims priority to and incorporates by reference the entire contents of Japanese Patent Application No. 2012-252423 filed in Japan on Nov. 16, 2012.

1. Field of the Invention

The present invention relates to a sheet processing apparatus, an image forming system, and a sheet folding method. In particular, the present invention relates to a sheet processing apparatus that folds a sheet recording medium (hereinafter, referred to as “a sheet”), such as a sheet of paper, a transfer sheet, a printing sheet, or an overhead projector (OHP) sheet, conveyed thereto, an image forming system including the sheet processing apparatus and an image forming apparatus, such as a copier, a printer, a facsimile machine, or a digital multifunction peripheral, and a sheet folding method performed by the sheet processing apparatus.

2. Description of the Related Art

Sheet processing apparatuses that fold a sheet conveyed from an image forming apparatus have been known as disclosed in, for example, Japanese Patent Application Laid-open No. 2006-117383. The sheet processing apparatus disclosed in the above document includes a first stop member, which is arranged in a second conveying path and the position of which can be changed to stop the leading end of a sheet; a conveying roller pair formed of a first conveying roller and a second conveying roller that sandwich a deflected portion of the sheet formed by the first stop member to thereby form a crease; a second stop member, which is arranged in a first conveying path and the position of which can be moved to stop the sheet that has passed through between the conveying roller pair; and a conveying roller pair formed of the second conveying roller and a third conveying roller that sandwich a deflected portion of the sheet formed by the second stop member to thereby form a crease. In the sheet processing apparatus, the stop position of the second stop member is controlled to perform four-folding.

In the technology as described above, the apparatus includes, for a folding process, a stopper and a dedicated path branching from a conveying path used to convey a sheet from an upstream device to a downstream device, and performs the folding process based on a so-called end-abutting in which a leading end of a sheet is caused to abut. That is, in the folding process, the sheet is caused to abut against the stopper in the dedicated path to adjust a folding position and form the deflected portion, and the deflected portion is nipped by a folding unit to fold the sheet.

However, in the sheet processing apparatus disclosed in Japanese Patent Application Laid-open No. 2006-117383, it is necessary to provide a branch path branching from a conveying path used to convey a sheet from an upstream device to a downstream device, and a stopper against which the leading end of the sheet is caused to abut to adjust the folding position. Furthermore, the position of the stopper needs to be changed depending on the length of the sheet or a type of folding. Therefore, a large moving range of the stopper needs to be ensured and a moving mechanism for moving the stopper needs to be provided. To ensure the moving range and provide the moving mechanism, the size of the apparatus is increased.

Therefore, there is a need to enable a folding process with a conveying path of a short length and reduce the size of the apparatus.

It is an object of the present invention to at least partially solve the problems in the conventional technology.

A sheet processing apparatus includes: a first pair of conveying members that convey a sheet; a second pair of conveying members that receive the sheet conveyed by the first pair of the conveying members and further conveys the sheet to a subsequent stage; and a third pair of conveying members that fold the sheet by rotating the second pair of the conveying members in a reverse direction while the sheet is held by the first pair of the conveying members and the second pair of the conveying members. One of the conveying members of the second pair serves as one of the conveying members of the third pair.

A sheet processing apparatus includes: a first conveying member that conveys a sheet along a first conveying path; a second conveying member including a first conveying roller, a second conveying roller, a third conveying roller, and a fourth conveying roller; and a second conveying path though which a sheet subjected to a folding process is discharged. The first conveying roller forms a nip with the second conveying roller while sandwiching the first conveying path. The fourth conveying roller forms a nip with the second conveying roller while sandwiching the second conveying path. The third conveying roller forms a nip with the second conveying roller, between the first conveying path and the second conveying path. The second conveying roller is rotated in a reverse direction while the sheet is held by the first conveying member and the second conveying member, to thereby fold the sheet by the nip between the second conveying roller and the third conveying roller to form a first crease. A regulator member regulates a leading end at which the first crease is formed, in the second conveying path, to thereby fold the sheet by the nip between the second conveying roller and the fourth conveying roller to form a second crease.

A sheet processing apparatus includes: a first conveying member that conveys a sheet along a first conveying path; a second conveying member including a first conveying roller, a second conveying roller, and a third conveying roller; a second conveying path through which a sheet subjected to a folding process is discharged; and a fourth conveying roller that forms a nip with the third conveying roller. The first conveying roller forms a nip with the second conveying roller while sandwiching the first conveying path. The fourth conveying roller forms a nip with the third conveying roller while sandwiching the second conveying path. The third conveying roller forms a nip with the second conveying roller, between the first conveying path and the second conveying path. The second conveying roller is rotated in a reverse direction while the sheet is held by the first conveying member and the second conveying member, to thereby fold sheet by the nip between the second conveying roller and the third conveying roller to form a first crease. A regulator member regulates a leading end at which the first crease is formed, in the second conveying path, to thereby fold the sheet by the nip between the third conveying roller and the fourth conveying roller to form a second crease.

The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.

FIG. 1 is a diagram illustrating an overall configuration of an image forming system according to an embodiment of the present invention;

FIG. 2 is a diagram illustrating an overall configuration of an image forming system according to another embodiment of the present invention;

FIG. 3 is a diagram illustrating a folding mechanism of a folding apparatus illustrated in FIG. 1 and FIG. 2 ;

FIG. 4 is a block diagram illustrating a control configuration of the image forming system according to the embodiment of the present invention;

FIG. 5 is a diagram for explaining operation in an initial state before a sheet is conveyed from the image forming apparatus when two-folding is performed;

FIG. 6 is a diagram for explaining operation when the sheet is fed from the image forming apparatus to a first conveying path;

FIG. 7 is a diagram for explaining operation when the sheet is conveyed toward a folding position by a first conveying member and a second conveying member;

FIG. 8 is a diagram for explaining operation when the second conveying member is rotated in a reverse direction and the sheet is folded at a two-folding position by the second conveying member;

FIG. 9 is a diagram for explaining operation when the sheet folded in two by the second conveying member is conveyed through a second conveying path toward a third conveying member;

FIG. 10 is a diagram for explaining operation when a crease of the sheet is enhanced by the third conveying member and the sheet is further conveyed through the second conveying path;

FIG. 11 is a diagram for explaining operation when the sheet is conveyed from the second conveying path to the first conveying path;

FIG. 12 is a diagram for explaining operation when the two-folded sheet conveyed back to the first conveying path is discharged;

FIG. 13 is a diagram for explaining operation in an initial state before a sheet is conveyed from the image forming apparatus when Z-folding is performed;

FIG. 14 is a diagram for explaining operation when the sheet is fed from the image forming apparatus side to the first conveying path;

FIG. 15 is a diagram for explaining operation when the sheet is conveyed toward a folding position by the first and the second conveying members;

FIG. 16 is a diagram for explaining operation when the second conveying member is rotated in a reverse direction and the sheet is folded at a first folding position for the Z-folding by the second conveying member;

FIG. 17 is a diagram for explaining operation when the sheet subjected to the first folding by the second conveying member is conveyed through the second conveying path toward the third conveying member;

FIG. 18 is a diagram for explaining operation when the sheet is further conveyed by the third conveying member on the second conveying path;

FIG. 19 is a diagram for explaining operation when the third conveying member is rotated in a reverse direction from the state illustrated in FIG. 18 and the sheet is deflected just before a nip of the second conveying member on the second conveying path;

FIG. 20 is a diagram for explaining operation when the sheet is subjected to second folding by the second conveying member from the state illustrated in FIG. 19 ;

FIG. 21 is a flowchart illustrating the flow for controlling each of the units for the Z-folding;

FIG. 22 is a diagram for explaining operation in an initial state before a sheet is conveyed from the image forming apparatus when inward three-folding is performed;

FIG. 23 is a diagram for explaining operation when the sheet is fed from the image forming apparatus to the first conveying path;

FIG. 24 is a diagram for explaining operation when the sheet is conveyed toward a folding position by the first and the second conveying members;

FIG. 25 is a diagram for explaining operation when the second conveying member is rotated in a reverse direction and the sheet is folded at a first folding position for the inward three-folding by the second conveying member;

FIG. 26 is a diagram for explaining operation when the sheet subjected to the first folding by the second conveying member is conveyed through the second conveying path toward the third conveying member;

FIG. 27 is a diagram for explaining operation when the sheet is further conveyed by the third conveying member on the second conveying path;

FIG. 28 is a diagram for explaining operation when the third conveying member is rotated in a reverse direction from the state illustrated in FIG. 27 and the sheet is deflected just before the nip of the second conveying member on the second conveying path;

FIG. 29 is a diagram for explaining operation when the sheet is folded in two by the second conveying member from the state illustrated in FIG. 28 ;

FIG. 30 is a diagram for explaining operation in an initial state before a sheet is conveyed from the image forming apparatus when outward three-folding is performed;

FIG. 31 is a diagram for explaining operation when the sheet is fed to the first conveying path from the image forming apparatus;

FIG. 32 is a diagram for explaining operation when the sheet is conveyed toward a folding position by the first and the second conveying members;

FIG. 33 is a diagram for explaining operation when the second conveying member is rotated in a reverse direction and the sheet is folded at a first folding position for the outward three-folding by the second conveying member;

FIG. 34 is a diagram for explaining operation when the sheet subjected to the first folding by the second conveying member is conveyed through the second conveying path toward the third conveying member;

FIG. 35 is a diagram for explaining operation when the sheet is further conveyed by the third conveying member on the second conveying path;

FIG. 36 is a diagram for explaining operation when the third conveying member is rotated in a reverse direction from the state illustrated in FIG. 35 and the sheet is deflected just before the nip of the second conveying member on the second conveying path;

FIG. 37 is a diagram for explaining operation when the sheet is subjected to second folding by the second conveying member from the state illustrated in FIG. 36 ;

FIGS. 38A to 38C are diagrams for explaining states of the Z-folding, the inward three-folding, and the outward three-folding;

FIG. 39 is a diagram illustrating a modification of the second conveying member of the folding mechanism illustrated in FIG. 3 ; and

FIG. 40 is a diagram illustrating a modification of the third conveying member of the folding mechanism illustrated in FIG. 3 .

In an embodiment of the present invention, a sheet folding position is adjusted by a nip and a reverse movement of a conveying member provided on a sheet conveying path, and a folding process is performed by the conveying member.

Embodiments of the present invention will be explained in detail below with reference to the accompanying drawings.

FIG. 1 is a diagram illustrating an overall configuration of an image forming system according to an embodiment of the present invention. In FIG. 1 , an image forming system 1 according to the embodiment mainly includes an image forming apparatus 200 , a folding apparatus 100 , and a post-processing apparatus 300 . The folding apparatus 100 is disposed between the preceding image forming apparatus 200 and the subsequent post-processing apparatus 300 . The folding apparatus 100 receives a sheet on which an image is formed by the image forming apparatus 200 , performs a predetermined folding process on the sheet, and conveys the sheet to the post-processing apparatus 300 . The post-processing apparatus 300 performs post-processing, such as aligning, stitching, or bookbinding, on a sheet subjected to the folding process or a sheet that is not subjected to the folding process.

FIG. 2 is a diagram illustrating an overall configuration of an image forming system according to another embodiment of the present invention. In FIG. 2 , the folding apparatus 100 is of a so-called body inside installation type and is provided in a sheet discharge unit inside the image forming apparatus 200 . In the image forming system 1 illustrated in FIG. 2 , the folding apparatus 100 is disposed in a body inside sheet discharge unit 200 a of the image forming apparatus 200 , and only a discharge tray 400 protrudes from the footprint of the image forming apparatus 200 . Therefore, the size of the system is greatly reduced compared with the system illustrated in FIG. 1 .

FIG. 3 is a diagram illustrating a folding mechanism of the folding apparatus 100 illustrated in FIG. 1 and FIG. 2 .

The folding apparatus 100 includes two conveying paths, that is, a first conveying path W 1 and a second conveying path W 2 . A first conveying member F 1 , a second conveying member F 2 , and a third conveying member F 3 are arranged along the two conveying paths W 1 and W 2 . The second conveying member F 2 is arranged so as to sandwich the first conveying path W 1 and the second conveying path W 2 and has a function to fold a sheet P and send the sheet P from the first conveying path W 1 to the second conveying path W 2 .

The first conveying member F 1 includes a first conveying roller pair R 1 . The second conveying member F 2 includes a first conveying roller R 2 , a second conveying roller R 3 , a third conveying roller R 4 , and a fourth conveying roller R 5 . The third conveying member F 3 includes a second conveying roller pair R 6 . The first and the second conveying roller pairs R 1 and R 6 (the first and the third conveying members F 1 and F 3 ) are driven by a first drive motor M 1 and a third drive motor M 3 , respectively, and give conveying force to the sheet P.

The first conveying roller pair R 1 is arranged near an entrance of the folding apparatus 100 on the first conveying path W 1 , receives the sheet P from the preceding image forming apparatus 200 , and conveys the sheet P downstream in the folding apparatus 100 by being driven by the first drive motor M 1 .

The second conveying path W 2 of the embodiment is configured such that an end portion W 2 a on the downstream side in the sheet conveying direction (a sheet discharge side) is connected to the downstream part of the first conveying path W 1 (the connection is not illustrated in the drawings), and an end portion W 2 b on the upstream side in the sheet conveying direction is connected to the part of the first conveying path W 1 upstream of the first conveying roller pair R 1 (see FIG. 5 ). Furthermore, the first conveying path W 1 is connected to the second conveying path W 2 via a communication path W 2 c at the installation position of the second conveying member F 2 downstream of the first conveying roller pair R 1 .

In the second conveying member F 2 , the first and the second conveying rollers R 2 and R 3 are arranged opposite each other across the first conveying path W 1 , and a second nip N 2 is formed therebetween. Furthermore, the second and the third conveying rollers R 3 and R 4 are arranged opposite each other between the first conveying path W 1 and the second conveying path W 2 , and a third nip N 3 is formed therebetween. A path in which guide is performed by the third nip N 3 functions as the communication path W 2 c for guiding the sheet from the first conveying path W 1 to the second conveying path W 2 . Moreover, the second and the fourth conveying rollers R 3 and R 5 are arranged opposite each other across the second conveying path W 2 , and a fourth nip N 4 is formed therebetween.

The first to the fourth conveying rollers R 2 to R 5 are driven by a second drive motor M 2 that drives the second conveying roller R 3 . That is, the second conveying member F 2 is driven by the second drive motor M 2 . The second drive motor M 2 can rotate both in a forward direction and a reverse direction, and the rotation direction is changed to convey the sheet P and perform a folding process. The second conveying member F 2 may be formed by an adhesive conveying roller pair or a suction belt, instead of the conveying roller pair.

In the second conveying member F 2 , the second conveying roller R 3 serves as a driving conveying roller and the first, the third, and the fourth conveying rollers R 2 , R 4 , and R 5 serve as driven conveying rollers that rotate by being in contact with the second conveying roller R 3 . The second and the third conveying rollers R 3 and R 4 serve as a first folding means, and the second and the fourth conveying rollers R 3 and R 5 serve as a second folding means.

A first compression spring S 2 , a second compression spring S 3 , and a third compression spring S 4 (which are elastic members) apply elastic force to the first, the third, and the fourth conveying rollers R 2 , R 4 , and R 5 , respectively, toward the second conveying roller R 3 , so that the contact with the second conveying roller R 3 is maintained. Therefore, the three conveying rollers R 2 , R 4 , and, R 5 are driven by receiving the driving force from the second conveying roller R 3 .

The first conveying roller pair R 1 is formed of a driving conveying roller R 1 a and a driven conveying roller R 1 b , and the first drive motor M 1 gives driving force to the driving conveying roller R 1 a . A first compression spring S 1 applies elastic force to the driven conveying roller R 1 b toward the driving conveying roller R 1 a , so that the driven conveying roller R 1 b comes in contact with the driving conveying roller R 1 a at a first nip N 1 and is driven in that state. The second conveying roller pair R 6 is formed of a driving conveying roller R 6 a and a driven conveying roller R 6 b , and the third drive motor M 3 gives driving force to the driving conveying roller R 6 a . A fifth compression spring S 5 applies an elastic force to the driven conveying roller R 6 b toward the driving conveying roller R 6 a , so that the driven conveying roller R 6 b comes in contact with the driving conveying roller R 6 a at a fifth nip N 5 and is driven in that state.

A first sheet detection sensor SN 1 is disposed just before the first conveying roller pair R 1 in the first conveying path W 1 . A second sheet detection sensor SN 2 is disposed just after the first and the second conveying rollers R 2 and R 3 . A third sheet detection sensor SN 3 is disposed close to the second conveying roller pair R 6 on the side away from the fourth conveying roller R 5 in the second conveying path W 2 . The first sheet detection sensor SN 1 functions as an entrance sheet detection sensor and the second sheet detection sensor SN 2 functions as a discharge sheet detection sensor.

FIG. 4 is a block diagram illustrating a control configuration of the image forming system according to the embodiment.

In FIG. 4 , the folding apparatus 100 includes a control circuit provided with a microcomputer including a CPU 100 a , an input/output (I/O) interface 100 b , and the like. A signal from a CPU of the image forming apparatus 200 , each switch of an operation panel 201 , each sheet detection sensor (not illustrated), or the like is input to the CPU 100 a via a communication interface 100 c . The CPU 100 a performs predetermined control based on the signals input from the image forming apparatus 200 . The CPU 100 a also controls drive of solenoids and motors via drivers and motor drivers, and acquires information from the sheet detection sensors in the apparatus via the interface. Furthermore, for example, the CPU 100 a controls drive of motors via motor drives with respect to a control target via the I/O interface 100 b , and acquires sheet detection sensor information from the sheet detection sensors. The above control is performed by causing the CPU 100 a to read program codes stored in a read-only memory (ROM) (not illustrated), deploy the program codes into a random access memory (RAM) (not illustrated), and execute programs defined by the program code by using the RAM as a working area and a data buffer.

In the embodiment, the folding mechanism illustrated in FIG. 3 enables two-folding, Z-folding, inward three-folding, and outward three-folding. Each folding operation is performed based on instructions issued by the CPU 100 a illustrated in FIG. 4 .

FIG. 5 to FIG. 12 are diagrams for explaining operation of each of the units when two-folding is performed.

FIG. 5 illustrates an initial state before a sheet is conveyed from the image forming apparatus 200 . The sheet P is fed from the image forming apparatus 200 to the first conveying path W 1 as illustrated in FIG. 6 from the state illustrated in FIG. 5 . When the first sheet detection sensor (the entrance sheet detection sensor) SN 1 detects a leading end P 1 of the sheet P, the first drive motor M 1 starts rotating (in the direction of arrow R 1 ). When the sheet P enters the first nip N 1 of the first conveying roller pair R 1 , the sheet P is conveyed toward the downstream second conveying member F 2 by the first conveying roller pair R 1 . When the leading end reaches the first conveying member F 2 , the sheet P is nipped by the second nip N 2 between the first and the second conveying rollers R 2 and R 3 and is further conveyed downstream in the conveying direction.

When the second sheet detection sensor SN 2 detects the leading end P 1 of the sheet P, the second drive motor M 2 is decelerated and the sheet P is conveyed to a position corresponding to a protrusion amount Δ 0 that is set in advance for the two-folding ( FIG. 7 ). When the sheet reaches the position corresponding to the protrusion amount Δ 0 , in other words, the position causing the center portion of the sheet P in the conveying direction to be folded by the third nip N 3 , the rollers are temporarily stopped. Then, reverse rotation is started ( FIG. 8 ). In this case, the first conveying roller pair R 1 is also stopped in synchronization with the first and the second conveying rollers R 2 and R 3 , and thereafter, conveys the sheet P downstream in the conveying direction at the same speed as the first and the second conveying rollers R 2 and R 3 .

In this case, the second drive motor M 2 is controlled such that the second drive motor M 2 is not stopped immediately after the sheet P conveyed from the upstream crosses the detection position of the second sheet detection sensor SN 2 but is stopped after the sheet is conveyed by the movement amount Δ 0 that is set in advance, and thereafter rotates in the reverse direction. The movement amount Δ 0 is set by causing the CPU 100 a to receive data about the length of the sheet P in the conveying direction from the image forming apparatus 200 before a job is started (before image formation on the sheet P is started), automatically calculate the movement amount based on the data, and use the calculation result. It may be possible to store a table containing a relationship between a sheet size and the movement amount in a ROM or the like and set the movement amount based on the sheet size, instead of performing the calculation.

When the second drive motor M 2 rotates in the reverse direction, as illustrated in FIG. 8 , the sheet P is deflected toward the third nip N 3 between the second and the third conveying rollers R 3 and R 4 in the communication path W 2 c , and thereafter, the sheet P is folded by the third nip N 3 as illustrated in FIG. 9 and is conveyed toward the second conveying path W 2 with a crease P 2 at the leading end. Meanwhile, it may be possible to perform the same control by continuing the rotation in a sheet discharging direction without stopping the first conveying roller pair R 1 .

In the communication path 2 Wc, the first conveying path W 1 is opened at the side facing the third nip N 3 but is closed at the other side; therefore, the sheet P is deflected toward the third nip N 3 . Nevertheless, to prevent a sheet jam, it may be possible to dispose a guide claw (not illustrated) just before the second nip N 2 between the first and the second conveying rollers R 2 and R 3 to guide the direction toward which the sheet P is deflected, toward the third nip N 3 when the first and the second conveying rollers R 2 and R 3 are rotated in the reverse direction.

As illustrated in FIG. 9 , the crease P 2 of the sheet P folded by the third nip N 3 is guided toward the second conveying roller pair R 6 along the inclination of a downward slope of the second conveying path W 2 , and the crease is enhanced by the fifth nip N 5 of the second conveying roller pair R 6 . Thereafter, the sheet P is conveyed through a connection conveying path W 2 d connecting the second conveying path W 2 and the first conveying path W 1 and fed to the first nip N 1 of the first conveying roller pair R 1 from the upstream of the first conveying roller pair R 1 ( FIG. 10 and FIG. 11 ).

The sheet P fed to the first nip N 1 of the first conveying roller pair R 1 is further conveyed toward the second conveying member F 2 by the first conveying roller pair R 1 . Thereafter, as illustrated in FIG. 12 , the sheet P is sent to a pair of the first and the second conveying rollers R 2 and R 3 of the second conveying member F 2 and discharged to the subsequent stage by the first and the second conveying rollers R 2 and R 3 .

At this time, when a trailing end of the two-folded sheet passes by the third sheet detection sensor SN 3 , the second and the third drive motors M 2 and M 3 are stopped. If there is a next sheet, operation from FIG. 5 is repeated, and the two-folded sheet is discharged to the subsequent stage, in particular, to the post-processing apparatus 300 on the subsequent stage in the embodiment.

Incidentally, if the post-processing apparatus 300 is not installed in the subsequent stage, the sheet may be discharged to the discharge tray 400 that is provided instead of the post-processing apparatus 300 . Therefore, a system formed of the image forming apparatus 200 and the folding apparatus 100 is the minimum system configuration of the image forming system of the embodiment.

FIG. 13 to FIG. 20 are diagrams for explaining operation of each of the units when Z-folding is performed. FIG. 21 is a flowchart illustrating the flow for controlling each of the units.

The operation illustrated in FIG. 13 to FIG. 17 is the same as the operation illustrated in FIG. 5 to FIG. 9 except for the operation and the folding position of the two-folding.

In the Z-folding, when the first sheet detection sensor SN 1 detects the leading end P 1 of the sheet P (Step S 101 ), the first conveying roller pair R 1 serving as the first conveying member F 1 starts rotating, and when the leading end P 1 of the sheet P enters the first nip N 1 of the first conveying roller pair R 1 , the sheet P is conveyed toward the second conveying member F 2 (Step S 102 ).

When the sheet P is conveyed to a position just before the second nip N 2 between the second conveying roller R 3 and the third conveying roller R 4 (Step S 103 ), the second drive motor M 2 is driven to rotate the second conveying member F 1 in the direction of arrow in FIG. 15 (Step S 104 ). Incidentally, whether the sheet P reaches the position just before the second nip N 2 can be determined from, for example, the number of driving steps of the first drive motor M 1 that drives the first conveying member F 1 . To perform the control as described above, in the embodiment, the first, the second, and the third drive motors M 1 , M 2 , and M 3 are each formed by a stepping motor. The first, the second, and the third drive motors M 1 , M 2 , and M 3 may be each formed by a motor other than the stepping motor. In this case, a control method corresponding to the type of an employed motor is applied.

After the second conveying member F 1 starts rotating in the direction of arrow in FIG. 15 at Step S 104 , a protrusion amount (a first protrusion amount) Δ 1 from the position of the second sheet detection sensor SN 2 is determined in order to set a folding position (Step S 105 ). In the Z-folding, as illustrated in FIG. 38A , mountain fold (first folding) is made at one-fourth of the total length of the sheet P from the leading end P 1 of the sheet P in the sheet conveying direction, and then valley fold (second folding) is made at a half of the total length of the sheet P. The position illustrated in FIG. 16 is a position where a crease P 3 is formed at one-fourth of the total length of the sheet P from the leading end P 1 of the sheet P. This position is also set by performing calculation or referring to a ROM table in the same manner as in the two-folding.

That is, the sheet P is conveyed until the first protrusion amount Δ 1 of the leading end P 1 of the sheet P is reached from a position where the leading end P 1 of the sheet P is detected by the second sheet detection sensor SN 2 . The first protrusion amount Δ 1 is fixed based on the length of the sheet and a type of folding, and is determined based on the amount of rotation of the first conveying roller R 2 . If the protrusion amount Δ 1 of the leading end P 1 of the sheet P is reached (YES at Step S 105 ), the second conveying member F 2 (the third conveying roller R 3 ) is temporarily stopped (Step S 106 ). At this time, the second conveying member F 2 is decelerated in the same manner as in the two-folding before stopping, and is controlled so as to stop with accuracy when the sheet reaches the position corresponding to the first protrusion amount Δ 1 . Subsequently, the second conveying member F 2 (the second conveying roller R 3 ) is rotated in the reverse direction as illustrated in FIG. 16 , which is opposite to the conveying direction until the operation in FIG. 15 , while maintaining the rotation of the first conveying member F 1 in the conveying direction (Step S 107 ). Incidentally, the first protrusion amount Δ 1 may be determined based on the amount of conveyance of the first conveying member F 1 from the position of the first sheet detection sensor SN 1 .

The sheet P is conveyed in the reverse direction due to the reverse rotation of the second conveying member F 2 (the second drive motor M 2 ). Meanwhile, the first conveying member F 1 is rotated in the same direction as the direction kept from FIG. 14 to convey the sheet P; therefore, similarly to the two-folding, a deflected portion is formed before the third nip N 3 ( FIG. 16 ). The deflected portion enters the third nip N 3 , at which the first folding is performed. As a result, the first crease P 3 is formed. The sheet P subjected to the first folding is conveyed to the second conveying path W 2 as illustrated in FIG. 17 .

The sheet P is conveyed along the inclination of the downward slope of the second conveying path W 2 , and is nipped and conveyed by the fifth nip N 5 of the second conveying roller pair R 6 that has started rotating in the direction of arrow illustrated in FIG. 18 , (Step S 107 ). If the third sheet detection sensor SN 3 detects the leading end (the first crease P 3 ) of the sheet P (Step S 108 ), and the sheet P reaches a position protruding from the detected position by a second protrusion amount Δ 2 , the third conveying member F 3 (the second conveying roller pair R 6 , i.e., the third drive motor M 3 ) is stopped (Step S 109 ), and starts rotating in the reverse direction (Step S 110 ), as illustrated in FIG. 19 . Incidentally, the second protrusion amount Δ 2 may be set as a protrusion amount from the fifth nip N 5 .

The second protrusion amount Δ 2 is fixed based on the length of the sheet and a type of folding, and is determined based on the amount of rotation of the second conveying roller pair R 6 (the number of driving steps of the third drive motor M 3 ) similarly to the first protrusion amount Δ 1 . Furthermore, the third conveying member F 3 (the second conveying roller pair R 6 ) is rotated in the reverse direction while the second conveying member F 2 (the second and the third conveying rollers R 3 and R 4 ) is kept rotating in the rotation direction illustrated in FIG. 17 and FIG. 18 . Therefore, as illustrated in FIG. 19 , a deflected portion of the sheet P is formed in the communication path W 2 c at the downstream of the third nip N 3 .

If the second and the third conveying members F 2 and F 3 are kept driving in the rotation direction as illustrated in FIG. 19 , the deflected portion enters the fourth nip N 4 between the second conveying roller R 3 and the fourth conveying roller R 5 , and the sheet P is conveyed toward the end portion W 2 a of the second conveying path W 2 on the sheet discharge side. During the conveyance, the second folding is performed as illustrated in FIG. 20 , so that a second crease P 4 is formed on the sheet P. The sheet P subjected to the second folding is conveyed from the end portion W 2 a on the sheet discharge side to the post-processing apparatus 300 on the subsequent stage via the first conveying path W 1 . Alternatively, the sheet P may be discharged to the discharge tray 400 .

Incidentally, in FIG. 20 , after the third sheet detection sensor SN 3 detects that the trailing end of the sheet P has passed (Step S 111 ) and the trailing end of the sheet P also passes through the fourth nip N 4 , the rotation of the second and the third conveying members F 2 and F 3 (the second and the third drive motors M 2 and M 3 ) is stopped (Step S 112 ). Furthermore, after the first sheet detection sensor SN 1 detects the trailing end of the sheet as illustrated in FIG. 19 and the trailing end of the sheet is separated from the first nip N 1 , the rotation of the first drive motor M 1 is stopped.

Other operations that are not described above are the same as those of the two-folding.

FIG. 22 to FIG. 29 are diagrams for explaining operation of each of the units when inward three-folding is performed. FIG. 30 to FIG. 37 illustrate operation of each of the units when outward three-folding is performed.

In both of the cases, the operation is the same as the operation of the Z-folding; therefore, the same components are denoted by the same reference numerals and symbols, and the same explanation will not be repeated. However, the first and the second protrusion amounts Δ 1 and Δ 2 each being fixed based on the length of the sheet or a type of folding, a timing at which the second conveying roller R 3 of the second conveying member F 2 starts rotating in the reverse direction, and a timing at which the second conveying roller pair R 6 of the third conveying member F 3 starts rotating in the reverse direction differ from those in the Z-folding. FIG. 38B illustrates a state of the sheet P subjected to the inward three-folding, and FIG. 38C illustrates a state of the sheet P subjected to the outward three-folding. From the drawings, it is clear that the creases P 3 and P 4 in the Z-folding, creases P 5 and P 6 in the inward three-folding, and creases P 7 and P 8 in the outward three-folding differ in the position and the folding direction.

In the inward three-folding, the first crease P 5 is located at two-thirds of the total length of the sheet in the conveying direction from a leading end P 1 ( FIG. 38B ), and the first protrusion amount Δ 1 is set in accordance with this folding position. After the sheet protrudes by the first protrusion amount Δ 1 , the second conveying member F 2 is rotated in the reverse direction ( FIG. 25 ). Furthermore, the second crease P 6 is located at one-third of the total length of the sheet from the leading end P 1 ( FIG. 38B ), and the second protrusion amount Δ 2 is set in accordance with this folding position. In this case, similarly to the above, after the sheet protrudes by the second protrusion amount Δ 2 , the third conveying member F 3 is rotated in the reverse direction ( FIG. 28 ).

In contrast, in the outward three-folding, the first crease P 7 is located at one-third of the total length of the sheet in the conveying direction from the leading end P 1 of the sheet ( FIG. 38C ), and the first protrusion amount Δ 1 corresponds to this folding position. After the sheet protrudes by the first protrusion amount Δ 1 , the second conveying member F 2 is rotated in the reverse direction ( FIG. 33 ). Furthermore, the second crease P 6 is located at two-thirds of the total length of the sheet from the leading end P 1 ( FIG. 38C ), and the second protrusion amount Δ 2 corresponds to this folding position. In this case, similarly to the above, after the sheet protrudes by the second protrusion amount Δ 2 , the third conveying member F 3 is rotated in the reverse direction ( FIG. 36 ).

As described above, the folding mechanism illustrated in FIG. 3 enables to perform the two-folding, the Z-folding, the inward three-folding, and the outward three-folding on the sheet P.

FIG. 39 is a diagram illustrating a modification of the second conveying member F 2 of the folding mechanism illustrated in FIG. 3 .

In this modification, a sixth nip N 6 is formed between the third conveying roller R 4 and the fourth conveying roller R 5 to perform final folding, instead of the fourth nip between the second conveying roller R 3 and the fourth conveying roller R 5 as illustrated in FIG. 3 . Therefore, a fourth drive motor M 4 that drives a fourth conveying roller R 5 ′ is provided. Furthermore, the third conveying member F 3 is disposed on the left relative to the second conveying roller R 3 in FIG. 39 in accordance with the above modification.

Even in this modification, the sheet folded by the third nip N 3 is conveyed to the third conveying member F 3 along the inclination of the downward slope of the second conveying path W 2 . Then, the crease is enhanced by the second conveying roller pair R 6 of the third conveying member F 3 . Subsequently, the third conveying member F 3 is rotated in the reverse direction to deflect the sheet before the sixth nip N 6 , and the sheet is folded by the third conveying roller R 4 and the fourth conveying roller R 5 ′. Thereafter, the sheet is discharged to a sheet discharge side W 2 e of the second conveying path W 2 (a sheet feed side (the right side in FIG. 39 ) of the first conveying path W 1 ). Therefore, the sheet subjected to the Z-folding, the inward three-folding, or the outward three-folding is discharged.

FIG. 40 is a diagram illustrating a modification of the third conveying member F 3 of the folding mechanism illustrated in FIG. 3 .

In this modification, the third conveying member F 3 is formed by a leading-end stopper ST 1 that moves on the second conveying path W 2 , instead of the second conveying roller pair R 6 illustrated in FIG. 3 . This modification is an example in which a conventional stopper is partly applied. In FIG. 40 , the leading-end stopper ST 1 is arranged on a conveying belt ST 2 stretched between a driving roller R 7 and a driven roller R 8 and protrudes to cross the conveying direction of the second conveying path W 2 . Therefore, the position of the leading end of the sheet P in the conveying direction is regulated by the leading-end stopper ST 1 . In this configuration, the leading-end stopper ST 1 is moved along with the conveying belt ST 2 .

Therefore, the folding position of the sheet P corresponding to the second protrusion amount Δ 2 can be set unambiguously based on the position of the leading-end stopper ST 1 instead of based on the amount of rotation of the second conveying roller pair R 6 . The position of the leading-end stopper ST 1 is controlled based on the driving steps of the third drive motor M 3 that drives the driving roller. By comparison of FIG. 40 and FIG. 3 , a configuration using the conveying roller that is rotatable in the forward and the reverse directions as illustrated in FIG. 3 is advantageous to reduce the size of the apparatus.

Incidentally, while the conveying rollers are used as the first conveying member F 1 , the second conveying member F 2 , and the third conveying member F 3 in the embodiment, for example, air suction rollers may be used instead of the conveying rollers. Furthermore, an air suction belt may be used instead of the conveying roller at a portion irrelevant to the folding.

As is apparent from the above descriptions, the following advantageous effects can be achieved by the embodiments.

1) An apparatus includes a first pair of conveying members (R 1 a and R 1 b ) that convey a sheet (P), a second pair of conveying members (R 2 and R 3 ) that receive the sheet (P) conveyed by the first pair of the conveying members (R 1 a and R 1 b ) and further conveys the sheet (P) to a subsequent stage, and a third pair of conveying members (R 3 and R 4 ) that folds the sheet (P) by rotating the second pair of the conveying members (R 2 and R 3 ) in a reverse direction while the sheet (P) is held by the first pair of the conveying members (R 1 a and R 1 b ) and the second pair of the conveying member pairs (R 2 and R 3 ). One (R 3 ) of the conveying members (R 2 and R 3 ) of the second pair serves as one (R 3 ) of the conveying members (R 3 and R 4 ) of the third pair. Therefore, it becomes possible to perform a folding process with a conveying path of a short length without using a stopper, so that the size of the apparatus can be reduced. Furthermore, the second pair of the conveying members (R 2 and R 3 ) and the third pair of the conveying members (R 3 and R 4 ) can be driven by a single drive source, so that the size of the apparatus can further be reduced.

2) The apparatus further includes a fourth pair of conveying members (R 3 and R 5 ) that further fold the sheet P that has been folded by the third pair of the conveying members (R 3 and R 4 ), at the downstream of the third pair of the conveying members (R 3 and R 4 ). Therefore, three-folding, such as Z-folding, inward three-folding, and outward three-folding, can be performed only by combination of the conveying roller pairs.

3) One (R 3 ) of the conveying members (R 2 and R 3 ) of the second pair serves as one (R 3 ) of the conveying members (R 3 and R 5 ) of the fourth pair. Therefore, the second pair of the conveying members (R 2 and R 3 ) and the fourth pair of the conveying members (R 3 and R 4 ) can be driven by a single drive source and the size of the apparatus can be reduced.

4) The other one (R 4 ) of the conveying members (R 3 and R 4 ) of the third pair serves as one (R 4 ) of the conveying members (R 4 and R 5 ′) of the fourth pair. Therefore, three-folding, such as Z-folding, inward three-folding, and outward three-folding, can be performed only by combination of the conveying roller pairs.

5) The apparatus includes a first conveying path (W 1 ) through which the sheet is conveyed from the first pair of the conveying members (R 1 a and R 1 b ) to the second pair of the conveying members (R 2 and R 3 ), and a second conveying path W 2 through which the sheet folded by the third pair of the conveying members (R 3 and R 4 ) is discharged. The third pair of the conveying members (R 3 and R 4 ) is disposed between the first conveying path (W 1 ) and the second conveying path (W 2 ). Therefore, the folding process can be performed without using a conveying path that is formed to directly branch from the first conveying path (W 1 ). Furthermore, it is sufficient that the second conveying path (W 2 ) is long enough to discharge the folded sheet, so that the length of the conveying path can be minimized. Therefore, when the apparatus is combined with the image forming apparatus ( 200 ), it becomes possible to dispose a folding apparatus (sheet processing apparatus) ( 100 ) that can perform two-folding and three-folding, in a so-called body inside sheet discharge unit ( 200 a ) formed between the main body of the image forming apparatus ( 200 ) and an image reading apparatus.

6) The apparatus includes the first conveying path (W 1 ) through which the sheet is conveyed from the first pair of the conveying members (R 1 a and R 1 b ) to the second pair of the conveying members (R 2 and R 3 ), and the second conveying path (W 2 ) through which the sheet folded by the third pair of the conveying members (R 3 and R 4 ) is discharged. The fourth pair of the conveying member (R 3 , R 5 , R 4 , and R 5 ′) is disposed such that the conveying members sandwich the second conveying path (W 2 ). Therefore, it is possible to directly discharge the folded sheet (P).

7) The apparatus includes a setting member (R 6 ) that sets, in the second conveying path (W 2 ), a position of a leading end of the sheet folded by the third pair of the conveying members (R 3 and R 4 ), a first crease (P 3 , P 5 , or P 7 ) being formed at the leading end. Therefore, it is possible to set the position of a second crease by the setting member (R 6 ).

8) The setting member (R 6 ) is a pair of conveying members that convey the folded sheet (P) and set an amount of conveyance in accordance with a position where a second crease (P 4 , P 6 , or P 8 ) is to be formed. Therefore, it is possible to form the second crease (P 4 , P 6 , or P 8 ) with accuracy.

9) The setting member (R 6 ) is a regulator member (ST 1 ) that regulates the position of the leading end of the folded sheet being conveyed, in accordance with the position where the second crease (P 4 , P 6 , or P 8 ) is to be formed, the first crease being formed at the leading end. Therefore, a moving range of the regulator member (ST 1 ) in the second conveying path W 2 can be reduced, so that the size of the apparatus is less likely to increase.

10) The pairs of the conveying members are pairs of conveying rollers. Therefore, the apparatus can be constructed at low costs.

11) When the second pair of the conveying members (R 2 and R 3 ) is rotated in the reverse direction, the protrusion amount Δ 0 or Δ 1 from the second pair of the conveying members (R 2 and R 3 ) is set based on the size of the sheet and a type of sheet folding. Therefore, it is possible to set a folding position with a simple structure and with high accuracy.

12) The apparatus includes a first conveying member (F 1 ) that conveys the sheet (P) along the first conveying path (W 1 ), a second conveying member (F 2 ) that includes a first, a second, a third, and a fourth conveying rollers (R 2 , R 3 , R 4 , and R 5 ), and a second conveying path (W 2 ) through which the sheet (P) subjected to a folding process is discharged. The first conveying roller (R 2 ) forms a nip with the second conveying roller (R 3 ) while sandwiching the first conveying path (W 1 ), the fourth conveying roller (R 5 ) forms a nip with the second conveying roller (R 3 ) while sandwiching the second conveying path (W 2 ), the third conveying roller (R 4 ) forms a nip with the second conveying roller (R 3 ), between the first conveying path (W 1 ) and the second conveying path (W 2 ), the second conveying roller (R 3 ) is rotated in a reverse direction while the sheet (P) is held by the first conveying member (F 1 ) and the second conveying member (F 2 ) to thereby fold the sheet (P) by the nip between the second conveying roller (R 3 ) and the third conveying roller (R 4 ) to form a first crease (P 3 , P 5 , or P 7 ), the third conveying member (F 3 ) regulates a leading end at which the first crease is formed, in the second conveying path (W 2 ), to thereby fold the sheet (P) by the nip between the second conveying roller (R 3 ) and the fourth conveying roller (R 5 ) to form a second crease (P 4 , P 6 , or P 8 ). Therefore, it is possible to perform three-folding, such as Z-folding, inward three-folding, and outward three-folding, only by the conveying roller pairs. Consequently, it becomes possible to perform a folding process with a conveying path of a short length without using the stopper, enabling to reduce the size of the apparatus.

13) The apparatus includes a first conveying member (F 1 ) that conveys the sheet (P) along the first conveying path (W 1 ), a second conveying member (F 2 ) that includes a first, a second, and a third conveying rollers (R 2 , R 3 , and R 4 ), a second conveying path (W 2 ) through which the sheet (P) subjected to a folding process is discharged, and a fourth conveying roller (R 5 ′) that forms a nip with the third conveying roller (R 4 ). The first conveying roller (R 2 ) forms a nip with the second conveying roller (R 3 ) while sandwiching the first conveying path (W 1 ), the fourth conveying roller (R 5 ′) forms a nip with the third conveying roller (R 4 ) while sandwiching the second conveying path (W 2 ), the third conveying roller (R 4 ) forms a nip with the second conveying roller (R 3 ), between the first conveying path (W 1 ) and the second conveying path (W 2 ), the second conveying roller (R 3 ) is rotated in a reverse direction while the sheet (P) is held by the first conveying member (F 1 ) and the second conveying member (F 2 ) to thereby fold the sheet (P) by the nip between the second conveying roller (R 3 ) and the third conveying roller (R 4 ) to form the first crease (P 3 , P 5 , or P 7 ), the third conveying member (F 3 ) regulates the leading end at which the first crease is formed, in the second conveying path (W 2 ), to thereby fold the sheet (P) by the nip between the third conveying roller (R 4 ) and the fourth conveying roller (R 5 ′) to form the second crease (P 4 , P 6 , or P 8 ). Therefore, it becomes possible to perform three-folding, such as Z-folding, inward three-folding, or outward three-folding, by only the conveying roller pairs. Therefore, it is possible to perform a folding process with a conveying path of a short length without using a stopper, so that the size of the apparatus can be reduced.

Incidentally, when the folding apparatus 100 and the image forming apparatus 200 according to the embodiment are combined, the compact-size image forming system 1 can be structured, in which the folding apparatus 100 is incorporated in the body inside discharge unit 200 a of the image forming apparatus 200 .

In 1) to 13) described above, the reference numerals and symbols corresponding to the components of the embodiment of the present invention are denoted in parentheses to clarify a relationship between the configuration of the appended claims and the components of the embodiments.

According to the embodiments, it is possible to perform a folding process with a conveying path of a short length, so that the size of the apparatus can be reduced.

Although the invention has been described with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.