Patent Description:
There is known a sheet processing apparatus to fold a sheet-shaped medium (hereinafter referred to as "sheet") into a predetermined form. Further, there are known an image forming apparatus to form an image on a sheet and an image forming system including a sheet processing apparatus to fold the sheet on which the image is formed.

Furthermore, a sheet processing apparatus is known that has a configuration in which among a plurality of roller pairs disposed in a conveyance path to convey a sheet, a roller pair for folding process is disposed between an upstream roller pair and a downstream roller pair, and a folding process is performed by controlling the plurality of roller pairs (e.g., <CIT>).

In the sheet processing apparatus of <CIT>, the rotation directions of the upstream roller pair and the downstream roller pair are controlled to bend a sheet between the plurality of roller pairs. The bent portion of the sheet is nipped between the plurality of roller pairs to apply the folding process. <CIT> discloses the preamble of claim <NUM> and describes a post-processing device comprising a guide member guiding a sheet to a position where the pair of the folding rollers hold the sheet, an urging means pressing a tip of the guide member against the holding position of the pair of folding rollers, and a guide member drive means releasing the urging by the urging means. In a sheet feeding where the sheet is introduced in the sheet folding processing part, the guide member drive means is operated to move the guide member from a sheet feeding passage to a retreating position.

In the sheet processing apparatus disclosed in <CIT>, the rotation direction of the downstream roller pair is reversed at a predetermined timing to change the conveyance direction in which the sheet is conveyed downstream. At this time, the rotation direction of the upstream conveying roller pair is not switched, and the rotation in the conveyance direction is maintained. Accordingly, the downstream roller pair disposed downstream from the roller pair for the folding process and the upstream roller pair disposed upstream from the roller pair for the folding process rotate in different directions. That is, in the sheet processing apparatus disclosed in <CIT>, multiple drive systems need to be provided separately for the respective roller pairs.

Further, in the sheet processing apparatus disclosed in <CIT>, if the speed at which the downstream roller pair conveys the sheet is slightly faster than the speed at which the upstream roller pair conveys the sheet, the sheet is pulled between the two roller pairs. In this case, suitable looseness is not formed, which causes a folding failure. The rotation direction of the upstream roller pair disposed upstream on the conveyance path in the conveyance direction and the rotation direction of the downstream roller pair disposed downstream on the conveyance path in the conveyance direction need to be controlled separately. The rotation speed of each roller pair also needs to be controlled separately. At this point, the drive systems need to be provided separately for the respective roller pairs.

That is, in the related art, multiple drive systems that functions to perform the folding process needs to be provided separately for the respective roller pairs, and there is a problem that the whole sheet processing apparatus is likely to be large. Further, in the drive control of each conveyance roller pair for the folding process, there is a problem that the control system for finely adjusting the sheet conveyance speed is complicated.

An object of the present disclosure is to provide a sheet processing apparatus having a configuration in which a plurality of roller pairs for performing folding process are driven by a single drive system, and the rotation direction of each roller pair can be switched individually.

To solve the above-described problems, a sheet processing apparatus includes a plurality of roller pairs, a single driving force supply source, and a drive transmission mechanism. The plurality of roller pairs convey a sheet from upstream to downstream in a sheet conveyance direction, and include a first roller pair, a second roller pair, and a third roller pair. The second roller pair is disposed downstream from the first roller pair in the sheet conveyance direction. The third roller pair is disposed between the first roller pair and the second roller pair and forms a crease on the sheet. The single driving force supply source supplies a driving force to the first roller pair, the second roller pair, and the third roller pair. The drive transmission mechanism transmits the driving force to the first roller pair and the second roller pair in a manner such that a rotation direction of the first roller pair is not switched even in a case in which a direction of the driving force is switched such that a rotation direction of the second roller pair is switched when the first roller pair and the second roller pair are driven by the driving force from the driving force supply source.

According to the present disclosure, a plurality of roller pairs to perform a folding process can be driven by a single drive system, and the rotation directions of the plurality of roller pairs can be switched separately.

The present disclosure is configured so that a driving force to sandwich and reverse a conveyor provided in the original conveyance path is supplied by a single driving source. A folding of a sheet-shaped medium is performed with the driving force from the single drive source. Hereinafter, embodiments of the present disclosure are described with reference to the drawings.

Referring to <FIG>, a description is given of an image forming apparatus according to an embodiment of the present disclosure. As illustrated in <FIG>, a printer <NUM> serving as the image forming apparatus according to an embodiment of the present disclosure basically includes an image forming unit <NUM> and a sheet processing unit <NUM>. The sheet processing unit <NUM> is one of a sheet processing device and a sheet processing apparatus according to embodiments of the present disclosure. Details of the sheet processing unit <NUM> are described later.

The image forming unit <NUM> conveys a sheet P from a sheet storage unit accommodating the sheet P as a sheet-shaped medium to an image forming section that forms an image on the sheet P. The image forming unit <NUM> includes a conveyance mechanism that discharges the sheet P to the sheet processing unit <NUM> after an image formation. As illustrated in <FIG>, the printer <NUM> has, for example, a configuration that discharges the sheet P from right to left toward an operation panel <NUM> serving as an operation interface.

Hereinafter, embodiments of the present disclosure are premised on the configuration illustrated in <FIG>. In addition to the configuration illustrated in <FIG>, as illustrated in <FIG>, a printer <NUM> serving as an image forming apparatus according to an embodiment of the present disclosure may have a configuration that discharges the sheet P from left to right toward the operation panel <NUM>. Further, as illustrated in <FIG>, a printer <NUM> serving as an image forming apparatus according to an embodiment of the present disclosure may have a configuration that discharges the sheet P from the back side to the front side toward the operation panel <NUM>.

In any of the above-described embodiments, the sheet processing unit <NUM> is disposed at a discharge port where the sheet P is discharged from the image forming unit <NUM>, thus allowing the sheet P to be folded and discharged. The sheet processing unit <NUM> may be detachably attached with respect to the image forming unit <NUM> or may be incorporated as a part of the image forming unit <NUM>.

<FIG> is a schematic diagram illustrating a configuration of an image forming system <NUM> according to an embodiment of the present disclosure. In <FIG>, the image forming system <NUM> according to the present embodiment basically includes an image forming apparatus <NUM> and a folding processing apparatus <NUM> serving as the sheet processing apparatus. A sheet P on which an image is formed by the image forming apparatus <NUM> is conveyed to the folding processing apparatus <NUM>. The folding processing apparatus <NUM> performs a predetermined sheet folding operation to the sheet P and discharges the sheet P.

<FIG> illustrates an outline of a conveyance mechanism and a folding processing mechanism provided in the sheet processing unit <NUM>. As illustrated in <FIG>, the sheet processing unit <NUM> includes a first conveyor <NUM>, a second conveyor <NUM>, a first folding roller section <NUM>, a second folding roller section <NUM>, a discharge roller section <NUM>, a first sheet detector <NUM>, and a second sheet detector <NUM>. The sheet processing unit <NUM> includes a plurality of rollers and rotates a plurality of roller pairs including these rollers to fold a sheet P.

A conveyance path provided in the sheet processing unit <NUM> is distinguishable into a plurality of conveyance paths for convenience. A first conveyance path <NUM> is a conveyance path downstream from the first conveyor <NUM> and upstream from the second conveyor <NUM> in the conveyance direction of the sheet P to bend the sheet P when the sheet processing unit <NUM> forms a first crease on the sheet P. A second conveyance path <NUM> is a conveyance path downstream from the second conveyor <NUM> and includes a configuration of detecting an inversion timing of the sheet P when the sheet P is folded. A third conveyance path <NUM> is a conveyance path that branches from the first conveyance path <NUM>. The sheet P on which the first crease is formed is conveyed to the third coveyance path <NUM>. A fourth conveyance path <NUM> is a conveyance path that conveys the sheet P on which a second folding process has been performed in the first folding roller section <NUM> and includes a configuration of performing an additional-folding process.

The first conveyor <NUM> serving as a first conveying roller pair is disposed on the upstream side of the sheet processing unit <NUM> and disposed at a position to receive the sheet P discharged from the image forming unit <NUM>. The first conveyor <NUM> includes a first conveying drive roller <NUM> and a first conveying driven roller <NUM>. The first conveying drive roller <NUM> is a drive roller that rotates by a driving force from a drive motor <NUM> (serving as a driving force supply source). The first conveying driven roller <NUM> is a driven roller that rotates according to the rotation of the first conveying drive roller <NUM>.

The first conveying roller pair including the first conveying drive roller <NUM> and the first conveying driven roller <NUM> nips the sheet P. The first conveying roller pair rotates by the driving force from the drive motor <NUM> to convey the sheet P. The rotation direction of the first conveying drive roller <NUM> is a direction to move the sheet P from the upstream side to the downstream side in the conveyance direction defined as a direction in which the sheet P is folded and discharged. The first conveyor <NUM> corresponds to an upstream conveying roller pair disposed on the upstream side in the conveyance direction.

The second conveyor <NUM> (serving as a second conveying roller) pair is disposed downstream from the first conveyor <NUM> in the conveyance direction in the sheet processing unit <NUM> and conveys the sheet P together with the first conveyor <NUM> in the conveyance direction. The second conveyor <NUM> conveys a downstream portion of the sheet P in reverse toward the upstream side in the conveyance direction to form a bend for the folding process in the sheet P.

Hereinafter, the rotation of each roller to convey the sheet P in the conveyance direction illustrated in <FIG> is referred to as "forward rotation" or "rotate forward". The rotation of each roller to convey the sheet P in the direction opposite to the conveyance direction is referred to as "reverse rotation" or "rotate in reverse". The forward rotation corresponds to rotation in a first direction, and the reverse rotation corresponds to rotation in a second direction.

The second conveyor <NUM> includes a second conveying drive roller <NUM> and a second conveying driven roller <NUM>. The second conveying drive roller <NUM> is a drive roller that rotates by a driving force from the drive motor <NUM>. The second conveying driven roller <NUM> is a driven roller that rotates according to the rotation of the second conveying drive roller <NUM>.

The second conveying roller pair including the second conveying drive roller <NUM> and the second conveying driven roller <NUM> nips the sheet P. The second conveying roller pair rotates by the driving force from the drive motor <NUM> to convey the sheet P. The second conveying drive roller <NUM> rotates in two directions, that is, a direction to move the sheet P in the conveyance direction and a direction to reverse a downstream portion of the sheet P to the upstream side. The second conveyor <NUM> corresponds to a downstream conveying roller pair disposed downstream from the first conveyor <NUM> in the conveyance direction defined as a direction in which the sheet P is folded and discharged.

The first folding roller section <NUM> is disposed between the first conveyor <NUM> serving as the upstream conveying roller pair and the second conveyor <NUM> serving as the downstream conveying roller pair. The first folding roller section <NUM> serving as a third roller pair includes a first folding roller pair and a second folding roller pair. The first folding roller pair includes the second conveying drive roller <NUM> and a first folding roller <NUM>. The second folding roller pair includes the second conveying drive roller <NUM> and a second folding roller <NUM>. The first folding roller <NUM> and the second folding roller <NUM> are driven rollers that are rotated by the rotation of the second conveying drive roller <NUM>.

The second conveying drive roller <NUM> is rotated in a predetermined direction by the driving force from the drive motor <NUM>, with the first folding roller pair nipping the sheet P, to form the first crease on the sheet P. The sheet P on which the first crease is formed is conveyed to the third conveyance path <NUM>. The second conveying drive roller <NUM> is rotated in a predetermined direction by the driving force from the drive motor <NUM>, with the second folding roller pair nipping the sheet P on which the first crease is formed, to form a second crease on the sheet P. The sheet P on which the second crease is formed is conveyed to the fourth conveyance path <NUM>.

Since the first folding roller section <NUM> executes the folding process on the sheet P by the rotation of the second conveying drive roller <NUM> that functions as the drive roller, the folding process of the sheet P is controlled according to the rotation direction and the rotation speed of the second conveying drive roller <NUM>.

The second folding roller section <NUM> is disposed downstream from the first folding roller section <NUM> in the conveyance direction on the fourth conveyance path <NUM>. The second folding roller section <NUM> includes an additional-folding drive roller <NUM> and an additional-folding driven roller <NUM>. The additional-folding drive roller <NUM> is rotated by the driving force from the drive motor <NUM> in the predetermined direction. The additional-folding driven roller <NUM> is rotated according to the rotation of the additional-folding drive roller <NUM> in the predetermined direction. The additional-folding drive roller <NUM> and the additional-folding driven roller <NUM> are rotated with the sheet P on which the crease is formed is nipped in the first folding roller section <NUM>, to perform an additional-folding process on the sheet P. The sheet P on which the additional-folding process is performed is conveyed to the discharge roller section <NUM>.

The discharge roller section <NUM> includes a first discharge roller <NUM>, a second discharge roller <NUM>, and a third discharge roller <NUM>. The first discharge roller <NUM> is a drive roller that is rotated by a driving force from the drive motor <NUM>. The second discharge roller <NUM> and the third discharge roller <NUM> are driven rollers that are rotated by the rotation of the first discharge roller <NUM>.

When the sheet P that is conveyed by the first conveyor <NUM> and the second conveyor <NUM> through the second conveyance path <NUM> is discharged without a folding process, the sheet P is nipped and discharged by the first discharge roller <NUM> and the second discharge roller <NUM>. The sheet P that has been additionally folded in the second folding roller section <NUM> is nipped between and discharged by the first discharge roller <NUM> and the third discharge roller <NUM>.

The first sheet detector <NUM> is a sensor that detects a leading end of the sheet P conveyed by the first conveyor <NUM> and the second conveyor <NUM> and is disposed on the second conveyance path <NUM>. When the sheet P is folded, the first sheet detector <NUM> defines the switching timing at which the rotation direction of the second conveying drive roller <NUM> is changed after the sheet P is conveyed in the downstream direction by a predetermined amount from the detection of the leading end of the sheet P with the first sheet detector <NUM>. When the first folding roller section <NUM> forms a crease on the sheet P, the rotation direction of the second conveying drive roller <NUM> is changed at a timing that the sheet P is conveyed by a predetermined amount from the detection of the leading end of the sheet P with the first sheet detector <NUM>. As a result, the sheet P is bent between the first conveyor <NUM> and the second conveyor <NUM>, and the bent portion is guided to the first folding roller section <NUM>, thus allowing the first folding roller section <NUM> to perform the folding process.

The second sheet detector <NUM> is a leading end stopper that detects an end portion of the sheet P on which a crease is formed after passage between the second conveying drive roller <NUM> and the first folding roller <NUM>. The second sheet detector <NUM> is disposed on the third conveyance path <NUM>. When the leading end of the sheet P contacts the second sheet detector <NUM> and stops, a bend is formed on the sheet P pushed from the upstream in the vicinity of the first folding roller section <NUM>. This bend (i.e., a part of the rear end of the sheet P) is nipped between the second conveying drive roller <NUM> and the second folding roller <NUM>, and the second folding process is performed. The sheet P on which the second folding process is performed is conveyed to the second folding roller section <NUM> via the fourth conveyance path <NUM> by the driving force of the second conveying drive roller <NUM>.

As illustrated in <FIG> and <FIG>, the second sheet detector <NUM> is not limited to the leading end stopper and may be configured with a sensor and a roller pair whose rotation direction can be controlled, similarly to the first sheet detector <NUM>.

An outline of operations performed when the sheet processing unit <NUM> performs the folding process is described with reference to <FIG>. As illustrated in <FIG>, the sheet P is conveyed into the sheet processing unit <NUM> and is conveyed in the downstream direction by the first conveyor <NUM> and the second conveyor <NUM>. The rotation direction of the second conveying drive roller <NUM> at this time is a counterclockwise (CCW) direction when the second conveying drive roller <NUM> is viewed from the positive direction of the X axis with respect to the Y-Z plane in <FIG>. The rotation direction of the second conveying driven roller <NUM> driven by the second conveying drive roller <NUM> is a clockwise (CW) direction when the second conveying driven roller <NUM> is similarly viewed from the positive direction of the X axis with respect to the Y-Z plane. <FIG> are also viewed from the same direction.

Similarly, in <FIG>, the rotation direction of the first conveying drive roller <NUM> is the CW direction, and the rotation direction of the first conveying driven roller <NUM> is the CCW direction. That is, the sheet P nipped in the first conveyor <NUM> is conveyed in the conveyance direction. The leading end of the sheet P nipped by the second conveyor <NUM> is also conveyed to the second conveyance path <NUM>. Thereafter, the leading end of the sheet P is detected by the sensor of the first sheet detector <NUM>. After the sheet P is conveyed by a certain distance from the detection of the leading end, the rotation direction of the second conveying drive roller <NUM> is reversed to be the CW direction as illustrated in <FIG>.

Even if the rotation direction of the second conveying drive roller <NUM> is switched from the CCW direction to the CW direction, the rotation direction of the first conveying drive roller <NUM> is not switched and is maintained to be the CW direction. At this time, a downstream portion of the sheet P in the conveyance direction is conveyed in reverse from the downstream to the upstream. An upstream portion of the sheet P is conveyed from the upstream to the downstream as before. As a result, the sheet P is bent between the second conveyor <NUM> and the first conveyor <NUM>. If this bent portion is formed toward the first folding roller section <NUM>, the state of the sheet P shifts to such a state as illustrated in <FIG>.

As illustrated in <FIG>, the bent portion of the sheet P is nipped between the second conveying drive roller <NUM> and the first folding roller <NUM>. The bent portion of the sheet P passes through the nip of the second conveying drive roller <NUM> and the first folding roller <NUM> due to the rotation of the second conveying drive roller <NUM>, so that the first crease is formed. At this time, the conveyance direction of the sheet P by the first conveyor <NUM> is as before. The upstream portion of the sheet P is conveyed in the direction as before. The downstream portion of the sheet P passes through the first folding roller section <NUM> and is conveyed to the third conveyance path <NUM> branching from the first conveyance path <NUM>.

After that, the end portion (i.e., the portion where the crease is formed) of the sheet P on the third conveyance path <NUM> side contacts the leading end stopper as the second sheet detector <NUM> (see <FIG>) and stops. At this time, the upstream portion of the sheet P is continuously conveyed to the third conveyance path <NUM> by the first conveyor <NUM>, the second conveying drive roller <NUM>, and the first folding roller <NUM>. As a result, the sheet P is bent in the vicinity of the second conveying drive roller <NUM> and the second folding roller <NUM>.

As illustrated in <FIG>, the bent portion of the sheet P is nipped between the second conveying drive roller <NUM> and the second folding roller <NUM> and is conveyed toward the second folding roller section <NUM>.

As illustrated in <FIG>, the sheet P on which the crease is formed by the second conveying drive roller <NUM> and the second folding roller <NUM> is discharged to the fourth conveyance path <NUM>.

Next, a description is given of the sheet processing unit <NUM> according to a first embodiment of the present disclosure. <FIG> are explanatory diagrams illustrating a configuration of a drive system of the conveyance roller pairs of the sheet processing unit <NUM>. As illustrated in <FIG>, the drive system of the sheet processing unit <NUM> mainly includes the drive motor <NUM> (serving as the driving force supply source) and a second-conveying-roller-pair drive gear DG20. The second-conveying-roller-pair drive gear DG20 is driven by the drive motor <NUM> and transmits the driving force. Note that in <FIG> and <FIG>, for convenience of explanation, the first folding roller <NUM> and the first conveying driven roller <NUM> are omitted.

The second-conveying-roller-pair drive gear DG20 is attached to a second conveying roller drive shaft J2 as a rotation shaft of the second conveying drive roller <NUM>. Accordingly, the rotation direction of the second conveying drive roller <NUM> follows the rotation direction of the drive motor <NUM> via the second-conveying-roller-pair drive gear DG20.

The drive transmission system of the sheet processing unit <NUM> includes a plurality of gears that are combined so as to be rotated by the rotation of the second-conveying-roller-pair drive gear DG20. As illustrated in <FIG>, the drive transmission system includes a first transmission gear AG11 and a third transmission gear AG13. The first transmission gear AG11 is meshed with the second-conveying-roller-pair drive gear DG20. The third transmission gear AG <NUM> is similarly meshed with the second-conveying-roller-pair drive gear DG20. Further, the drive transmission system includes a second transmission gear AG12 that is meshed with the first transmission gear AG11. The drive transmission system includes a first-conveying-roller-pair drive first gear DG11 and a first-conveying-roller-pair drive second gear DG12. The first-conveying-roller-pair drive first gear DG11 is meshed with the second transmission gear AG <NUM>. The conveying roller pair drive second gear DG12 is meshed with the third transmission gear AG13.

The first-conveying-roller-pair drive first gear DG11 and the first-conveying-roller-pair drive second gear DG12 are attached to a first conveying roller drive shaft J1 that is the rotation shaft of the first conveying drive roller <NUM>.

A one-way clutch is built in each of the first-conveying-roller-pair drive first gear DG11 and the first-conveying-roller-pair drive second gear DG12. Each of the one-way clutches causes the first-conveying-roller-pair drive first gear DG11 or the first-conveying-roller-pair drive second gear DG12 to rotate only in the CW direction to transmit the driving force to the first conveying roller drive shaft J1 and causes the first-conveying-roller-pair drive first gear DG11 or the first-conveying-roller-pair drive second gear DG12 so as not to rotate in the CCW direction, thus cutting off the driving force to the first conveying roller drive shaft J1.

A description is given of the drive transmission system having the above-described configurations with reference to <FIG> and <FIG>. <FIG> illustrates an example in which the sheet P is conveyed in the conveyance direction and each roller is rotated forward. <FIG> illustrates an example in which the second conveyor <NUM> is rotated in reverse so that the sheet P is folded.

As illustrated in <FIG>, when the second-conveying-roller-pair drive gear DG20 rotates in the CCW direction due to the rotation of the drive motor <NUM>, the first transmission gear AG11 rotates in the CW direction and the second transmission gear AG12 rotates in the CCW direction. At this time, the second conveyor <NUM> rotates forward. The driving force for rotating the first-conveying-roller-pair drive first gear DG11 in the CW direction is transmitted from the second transmission gear AG12 to the first-conveying-roller-pair drive first gear DG11. Since the one-way clutch built in the first-conveying-roller-pair drive first gear DG11 receives the driving force in the CW direction, the driving force for rotating the first conveying roller drive shaft J1 in the CW direction is transmitted to the first conveying roller drive shaft J1.

When the second-conveying-roller-pair drive gear DG20 rotates in the CCW direction due to the rotation of the drive motor <NUM>, the third transmission gear AG13 rotates in the CW direction, and the driving force for rotating the first-conveying-roller-pair drive second gear DG12 in the CCW direction is transmitted to the first-conveying-roller-pair drive second gear DG12. Since the one-way clutch built in the first-conveying-roller-pair drive second gear DG12 cuts off the driving force in the CCW direction, the driving force for rotating the first conveying roller drive shaft J1 in the CCW direction is not transmitted to the first conveying roller drive shaft J1.

Accordingly, as illustrated in <FIG>, when the second-conveying-roller-pair drive gear DG20 is rotated in the CCW direction by the drive motor <NUM>, the driving force transmitted by a first drive transmission path TP1 serving as a first drive transmission mechanism rotates the first conveying drive roller <NUM> in the CW direction. As a result, as illustrated in <FIG>, the first conveyor <NUM> and the second conveyor <NUM> convey the sheet P along the conveyance direction.

As illustrated in <FIG>, when the second-conveying-roller-pair drive gear DG20 is rotated in the CW direction by the drive motor <NUM>, the second conveyor <NUM> is rotated in reverse. When the first transmission gear AG11 rotates in the CCW direction, the second transmission gear AG12 rotates in the CW direction. Thus, the driving force is transmitted to the first-conveying-roller-pair drive first gear DG11 to rotate in the CCW direction. However, since the one-way clutch built in the first-conveying-roller-pair drive first gear DG11 cuts off the driving force in the CCW direction, the driving force for rotating the first conveying roller drive shaft J1 in the CCW direction is not transmitted to the first conveying roller drive shaft J1. Accordingly, since the first conveying roller drive shaft J1 does not rotate in the CCW direction, the first conveying drive roller <NUM> does not also rotate in the CCW direction. Note that, in <FIG>, for convenience of explanation, the first-conveying-roller-pair drive first gear DG11 is omitted.

When the second-conveying-roller-pair drive gear DG20 rotates in the CW direction due to the rotation of the drive motor <NUM>, the third transmission gear AG13 rotates in the CCW direction, and the driving force for rotating the first-conveying-roller-pair drive second gear DG12 in the CW direction is transmitted from the third transmission gear AG13 to the first-conveying-roller-pair drive second gear DG12. Since the one-way clutch built in the first-conveying-roller-pair drive second gear DG12 transmits the driving force in the CW direction, the driving force for rotating the first conveying roller drive shaft J1 in the CW direction is transmitted to the first conveying roller drive shaft J1.

Accordingly, as illustrated in <FIG>, when the second-conveying-roller-pair drive gear DG20 is rotated in the CW direction by the drive motor <NUM>, the driving force transmitted by a second drive transmission path TP2 serving as a second drive transmission mechanism rotates the first conveying drive roller <NUM> in the CW direction. As illustrated in <FIG>, the first conveyor <NUM> conveys the sheet P in the conveyance direction, and the second conveyor <NUM> conveys the sheet P in the direction opposite to the conveyance direction (i.e., the upstream side in the conveyance direction).

As described above, the sheet processing unit <NUM> according to the present embodiment has a plurality of drive transmission paths (i.e., the first drive transmission path TP1 and the second drive transmission path TP2) on which the rotation direction of the first conveying drive roller <NUM> is only in the CW direction regardless of whether the rotation direction of the rotation shaft of the drive motor <NUM> is the CW direction or the CCW direction.

When the rotation direction of the rotation shaft of the drive motor <NUM> is switched, the rotation direction of the second conveying drive roller <NUM> is switched. On the other hand, the rotation direction of the first conveying drive roller <NUM> may not be switched so that the first conveying drive roller <NUM> rotates only in a certain direction. Thus, the operations of the first conveyor <NUM> and the second conveyor <NUM> are controlled only by the drive force from the drive motor <NUM> serving as a single driving force supply source. That is, as described with reference to <FIG>, by switching the rotation direction of the drive motor <NUM> at a predetermined timing, the conveyance direction of the downstream portion of the sheet P can be switched to the direction opposite to the conveyance direction (i.e., the upstream side in the conveyance direction). The upstream portion of the sheet P can be conveyed continuously in the conveyance direction. As a result, as illustrated in <FIG>, the sheet P is inserted into the nip between the second conveying drive roller <NUM> and the first folding roller <NUM> while a bend is formed on the sheet P at a predetermined position, thus allowing a crease to be accurately formed at a predetermined position.

The rotational drive of the first folding roller section <NUM> after formation of the bend, and the rotational drive of the second folding roller section <NUM> and the discharge roller section <NUM> are also performed by the driving force of the drive motor <NUM>. Such a configuration can perform the folding process on the sheet P with a reduced size of the sheet processing unit <NUM>.

Next, a description is given of a sheet processing unit <NUM> according to a second embodiment of the present disclosure. <FIG> are diagrams illustrating a configuration of a drive transmission system of conveying roller pairs in the sheet processing unit <NUM> according to the second embodiment. As illustrated in <FIG> and <FIG>, the drive system of the sheet processing unit <NUM> mainly includes the drive motor <NUM> (serving as the driving force supply source) and a second-conveying-roller-pair drive gear DG200. The second-conveying-roller-pair drive gear DG200 is driven by the drive motor <NUM> and transmits the driving force.

The second-conveying-roller-pair drive gear DG200 is attached to the second conveying roller drive shaft J2 as the rotation shaft of the second conveying drive roller <NUM>. Accordingly, the rotation direction of the second conveying drive roller <NUM> is the same as the rotation direction of the second-conveying-roller-pair drive gear DG200 and follows the rotation direction of the drive motor <NUM>. When the drive motor <NUM> is rotated forward, the second conveying drive roller <NUM> and the second-conveying-roller-pair drive gear DG200 are also rotated forward. When the drive motor <NUM> is rotated in reverse, the second conveying drive roller <NUM> and the second-conveying-roller-pair drive gear DG200 are also rotated in reverse.

A drive transmission idler gear pulley GP103 meshes with the second-conveying-roller-pair drive gear DG200. The drive transmission idler gear pulley GP103 rotates as the driving force is transmitted to the drive transmission idler gear pulley GP103 by the rotation of the second-conveying-roller-pair drive gear DG200.

As illustrated in <FIG>, the drive transmission idler gear pulley GP103 is roughly classified into a large-diameter portion and a small-diameter portion. The large-diameter portion meshes with the second-conveying-roller-pair drive gear DG200 and a first-conveying-roller-pair drive gear DG101. A first timing belt <NUM> is wound around the small-diameter portion.

The first timing belt <NUM> is also wound around a first-conveying-roller-pair drive pulley <NUM> serving as a transmission mechanism of the first conveying roller drive shaft J1 that is the drive shaft of the first conveying drive roller <NUM>. Accordingly, when the drive transmission idler gear pulley GP103 rotates, the driving force thereof also rotate the first-conveying-roller-pair drive pulley <NUM> via the first timing belt <NUM>.

The first-conveying-roller-pair drive pulley <NUM> is attached to the first conveying roller drive shaft J1 serving as the rotation shaft of the first conveying drive roller <NUM>. The first-conveying-roller-pair drive gear DG101 is also attached to the first conveying roller drive shaft J1. The first-conveying-roller-pair drive gear DG101 also meshes with the large-diameter portion of the second-conveying-roller-pair drive gear DG200.

Accordingly, in the sheet processing unit <NUM> according to the present embodiment, the driving force supplied from the drive motor <NUM> drives the second conveying drive roller <NUM> and also drives the first conveying drive roller <NUM> by transmitting the driving force to the first conveying drive roller <NUM>.

The driving force transmission path to the first conveying drive roller <NUM> has a configuration in which two paths coexist. In the first path serving as the first drive transmission mechanism, as illustrated in <FIG>, the driving force transmitted from the second-conveying-roller-pair drive gear DG200 via the large diameter portion of the drive transmission idler gear pulley GP103 is transmitted to the small diameter portion of the drive transmission idler gear pulley GP103, the first timing belt <NUM>, and the first-conveying-roller-pair drive pulley <NUM>. In the second path serving as the second drive transmission mechanism, as illustrated in <FIG>, the driving force transmitted from the second-conveying-roller-pair drive gear DG200 via the large diameter portion of the drive transmission idler gear pulley GP103 is transmitted via the first-conveying-roller-pair drive gear DG101.

A one-way clutch is built in each of the first-conveying-roller-pair drive gear DG101 and the first-conveying-roller-pair drive pulley <NUM>. The one-way clutch transmits the driving force in only one direction and cut offs the driving force in the other direction so that corresponding one of the first-conveying-roller-pair drive gear DG101 and the first-conveying-roller-pair drive pulley <NUM> rotates forward (i.e., the rotation in the CW direction illustrated in <FIG>) but does not rotate in reverse.

A description is given of the driving system having the above-described configurations with reference to <FIG>. As illustrated in <FIG>, when the second-conveying-roller-pair drive gear DG200 rotates in the CCW direction due to the rotation of the drive motor <NUM>, the drive transmission idler gear pulley GP103 rotates in the CW direction. A driving force in the CCW direction is transmitted to the first-conveying-roller-pair drive gear DG101 that meshes with the large diameter portion of the drive transmission idler gear pulley GP103. However, the built-in one-way clutch cuts off the driving force.

At this time, the small diameter portion of the drive transmission idler gear pulley GP103 rotates in the CW direction, and the rotation is transmitted to the first-conveying-roller-pair drive pulley <NUM> via the first timing belt <NUM>. The first-conveying-roller-pair drive pulley <NUM> rotates in the CW direction, which is the same direction as the rotation direction of the drive transmission idler gear pulley GP103. The one-way clutch built in the first-conveying-roller-pair drive pulley <NUM> transmits the driving force for rotating the first-conveying-roller-pair drive pulley <NUM> in the CW direction. Accordingly, when the first-conveying-roller-pair drive pulley <NUM> rotates in the CW direction, the first conveying roller drive shaft J1 also rotates in the CW direction, and first conveying drive roller <NUM> rotates in the CW direction.

That is, in the second embodiment, the path through which the driving force is transmitted from the second-conveying-roller-pair drive gear DG200 to the first-conveying-roller-pair drive pulley <NUM> via the small diameter portion of the drive transmission idler gear pulley GP103 corresponds the first drive transmission path TP1 illustrated in <FIG>.

As illustrated in <FIG>, when the second-conveying-roller-pair drive gear DG200 rotates in the CW direction due to the rotation of the drive motor <NUM>, the drive transmission idler gear pulley GP103 rotates in the CCW direction. The first-conveying-roller-pair drive gear DG101 that meshes with the large diameter portion of the drive transmission idler gear pulley GP103 rotates in the CW direction. Since the first-conveying-roller-pair drive gear DG101 has a built-in one-way clutch so as to rotate in the CW direction, the driving force for rotating the first conveying roller drive shaft J1 in the CW direction is transmitted to the first conveying roller drive shaft J1, and the first conveying roller pair rotates forward.

At this time, the rotation of the small diameter portion of the drive transmission idler gear pulley GP103 is also transmitted to the first-conveying-roller-pair drive pulley <NUM> via the first timing belt <NUM>. The first-conveying-roller-pair drive pulley <NUM> rotates in the same direction (i.e., CCW direction) as the rotation direction of the drive transmission idler gear pulley GP103. In this case, the driving force for rotating the first-conveying-roller-pair drive pulley <NUM> in the CCW direction is transmitted to the first-conveying-roller-pair drive pulley <NUM>. However, this driving force is cut off by the one-way clutch. As a result, the rotation of the first-conveying-roller-pair drive pulley <NUM> is not transmitted to the first conveying drive roller <NUM>.

When the second conveying drive roller <NUM> rotates in the CW direction due to the rotation of the drive motor <NUM>, the driving force for rotating the first-conveying-roller-pair drive gear DG101 in the CW direction is transmitted from the second-conveying-roller-pair drive gear DG200 to the first-conveying-roller-pair drive gear DG101 via the large diameter portion of the drive transmission idler gear pulley GP103. Accordingly, the first conveying roller drive shaft J1 rotates in the CW direction.

That is, in the second embodiment, the path through which the driving force is transmitted from the second-conveying-roller-pair drive gear DG200 to the first-conveying-roller-pair drive gear DG101 via the large diameter portion of the drive transmission idler gear pulley GP103 corresponds the second drive transmission path TP2 illustrated in <FIG>.

As described above, when the rotation direction of the rotation shaft of the drive motor <NUM> is switched, the rotation direction of the second conveying drive roller <NUM> is switched. On the other hand, the rotation direction of the first conveying drive roller <NUM> is not switched and the first conveying drive roller <NUM> rotates only in a certain direction. Such a configuration, as described above, allows a plurality of conveying roller pairs to perform the folding process by the driving force of the drive motor <NUM> serving as the single driving force supply source at a predetermined timing. When the rotation direction of the drive motor <NUM> is switched. an upstream portion of the sheet P can be maintained as being conveyed in the conveyance direction while the direction of a downstream portion of the sheet P is switched to the upstream direction. As a result, as illustrated in <FIG>, the sheet P is inserted into the nip between the second conveying drive roller <NUM> and the first folding roller <NUM> while a bend is formed on the sheet P at a predetermined position, thus allowing a crease to be accurately formed at a predetermined position.

After the bend is formed, the rotational drive of the first folding roller section <NUM> and the rotational drive of the second folding roller section <NUM> and the discharge roller section <NUM> are also performed by the driving force of the drive motor <NUM>. Such a configuration can perform the folding process on the sheet P with a reduced size of the sheet processing unit <NUM>.

Referring to <FIG>, a description is given of the flow of a folding operation that can be performed in the configuration of the sheet processing unit <NUM> according to the second embodiment. The sheet processing unit <NUM> according to the present embodiment is disposed on the backward of the conveyance path of the sheet P. To facilitate the explanation, a state in which the configuration illustrated in <FIG> is viewed from the opposite side is illustrated in each of <FIG>. Accordingly, the rotation direction (CW or CCW direction) used in the description of <FIG> is opposite to the rotation direction (CW or CCW direction) illustrated in <FIG>.

In <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, and <FIG> illustrate the arrangement of the drive system that transmits the driving force to the conveying roller pairs to rotate in predetermined directions, and the rotation direction of the configuration of each drive system. <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, and <FIG> illustrate the arrangement and the rotation directions of the conveying roller pairs.

When the second-conveying-roller-pair drive gear DG200 rotates in the CW direction in <FIG>, the second conveyor <NUM> including the second conveying drive roller <NUM> and the second conveying driven roller <NUM> rotates forward. When the second-conveying-roller-pair drive gear DG200 rotates in the CW direction, the first-conveying-roller-pair drive gear DG101 also rotates in the CW direction. As illustrated in <FIG>, the drive transmission to the first conveying drive roller <NUM> is cut off by the action of the one-way clutch built in the first-conveying-roller-pair drive gear DG101.

On the other hand, when the second-conveying-roller-pair drive gear DG200 rotates in the CW direction, the drive transmission idler gear pulley GP103 rotates in the CCW direction. The rotation of the drive transmission idler gear pulley GP103 is transmitted to the first-conveying-roller-pair drive pulley <NUM> via the first timing belt <NUM> that meshes the small diameter portion of the drive transmission idler gear pulley GP103. The first-conveying-roller-pair drive pulley <NUM> rotates in the CCW direction, and the driving force in the CCW direction is transmitted to the first conveying drive roller <NUM>.

As a result, the driving force is transmitted to the first conveying drive roller <NUM>, and the first conveyor <NUM> including the first conveying drive roller <NUM> and the first conveying driven roller <NUM> also rotates forward. Note that "rotate forward" means the rotation direction of each roller that constitutes the first conveyor <NUM> and the second conveyor <NUM> when the sheet P is conveyed in the conveyance direction illustrated in <FIG>.

A second-conveying-driven-roller first gear SG201, a second-conveying-driven-roller second gear SG202, and a drive transmission idler gear G81 mesh with the small diameter portion (see <FIG>) of the second-conveying-roller-pair drive gear DG200. The second-conveying-driven-roller first gear SG201, the second-conveying-driven-roller second gear SG202, and the drive transmission idler gear G81 rotate in the direction opposite to the rotation direction of the second-conveying-roller-pair drive gear DG200. Accordingly, as illustrated in <FIG>, when the rotation direction of the second-conveying-roller-pair drive gear DG200 is in the CW direction, the second-conveying-driven-roller first gear SG201, the second-conveying-driven-roller second gear SG202, and the drive transmission idler gear G81 rotate in the CCW direction.

The second-conveying-driven-roller first gear SG201 rotates the first folding roller <NUM>. The second-conveying-driven-roller second gear SG202 rotates the second folding roller <NUM>. Accordingly, when the second-conveying-driven-roller first gear SG201 and the second-conveying-driven-roller second gear SG202 rotate in the CCW direction, the first folding roller <NUM> and the second folding roller <NUM> also rotate in the CCW direction.

An additional-folding drive gear G61 also meshes with the drive transmission idler gear G81. An additional-folding drive gear G62 meshes with the additional-folding drive gear G61. A second timing belt <NUM> is wound around the rotation shaft of the additional-folding drive gear G61. The second timing belt <NUM> is also wound around the rotation shaft of a discharge drive gear G71. With such a configuration, when the drive transmission idler gear G81 rotates, the driving force is transmitted to the additional-folding drive gear G61, the additional-folding driven gear G62, and the discharge drive gear G71, thus rotating each of the gears.

The additional-folding drive roller <NUM> is disposed on the rotation shaft of the additional-folding drive gear G61. The additional-folding driven roller <NUM> is disposed on the rotation shaft of the additional-folding driven gear G62. The first discharge roller <NUM> is disposed on the rotation shaft of the discharge drive gear G71.

Accordingly, when the second-conveying-roller-pair drive gear DG200 rotates in the CW direction, the drive transmission idler gear G81 rotates in the CCW direction, and the additional-folding drive gear G61 and the discharge drive gear G71 rotate in the CW direction. Then, the additional-folding driven gear G62 rotates in the CCW direction, and the discharge drive gear G71 rotates in the CW direction. As a result, the additional-folding drive roller <NUM> rotates in the CW direction, the additional-folding driven roller <NUM> rotates in the CCW direction, and the first discharge roller <NUM> rotates in the CW direction.

Subsequently, as illustrated in <FIG>, when the sheet P is carried in, the first conveying drive roller <NUM> and the first conveying driven roller <NUM> rotate forward by the driving force of the drive motor <NUM> (see <FIG>). The second conveying drive roller <NUM> and the second conveying driven roller <NUM> also rotate forward. Accordingly, the sheet P is conveyed in the conveyance direction. After the leading end of the sheet P is detected by the first sheet detector <NUM>, the sheet P is continuously conveyed to a designated length L, and the drive motor <NUM> is rotated in the reverse direction.

When the rotation direction of the drive motor <NUM> is switched, as illustrated in <FIG>, the second-conveying-roller-pair drive gear DG200 rotates in the CCW direction in <FIG>, and the rotation direction of the second conveyor <NUM> that includes the second conveying drive roller <NUM> and the second conveying driven roller <NUM> is reversed. On the other hand, when the second-conveying-roller-pair drive gear DG200 rotates in the CCW direction, the first-conveying-roller-pair drive gear DG101 also rotates in the CCW direction, so that the driving force in the CCW direction is transmitted to the first conveying drive roller <NUM>. At this time, the first-conveying-roller-pair drive pulley <NUM> rotates in the CW direction via the first timing belt <NUM> hung on the small diameter portion of the drive transmission idler gear pulley GP103. The drive transmission to the first conveying drive roller <NUM> is cut off by the action of the one-way clutch built in the first-conveying-roller-pair drive pulley <NUM> as illustrated in <FIG>.

With such a configuration, the first conveyor <NUM> including the first conveying drive roller <NUM> and the first conveying driven roller <NUM> also rotate forward. That is, while the conveyance direction of the downstream portion of the sheet P is switched to the direction opposite to the conveyance direction (i.e., the upstream side in the conveyance direction), the upstream portion of the sheet P can be conveyed continuously in the conveyance direction.

As a result, as illustrated in <FIG>, the sheet P is inserted into the nip between the second conveying drive roller <NUM> and the first folding roller <NUM> while a bend is formed on the sheet P in the vicinity of the nip between the second conveying drive roller <NUM> and the first folding roller <NUM> in the first conveyance path <NUM>, thus allowing a crease to be accurately formed at a predetermined position.

The bend of the sheet P is nipped between the second conveying drive roller <NUM> and the first folding roller <NUM> each rotating in the direction to convey the sheet P toward the third conveyance path <NUM>, and the first folding process is performed. Thereafter, when the sheet P continues to be conveyed toward the third conveyance path <NUM> as it is, as illustrated in <FIG>, the first crease moves to a position where the first crease contacts the second sheet detector <NUM> serving as the leading end stopper.

As illustrated in <FIG>, the leading end stopper includes a wall portion that contacts the sheet P and a shaft that fixes and holds the wall portion. The wall portion is rotatable with the shaft as the rotation center. By rotating the wall portion around the shaft to a predetermined position and then fixing the wall portion, the position of the second crease formed on the sheet P can be adjusted according to the type of folding. A leading end of the sheet P contacts the wall portion whose position has been adjusted, and a trailing end of the sheet P is continuously conveyed by the first conveyor <NUM>, the second conveying drive roller <NUM>, and the first folding roller <NUM>. Thus, a bend for folding the second crease on the sheet P is formed in the vicinity of the nip between the second conveying drive roller <NUM> and the second folding roller <NUM> in the third conveyance path <NUM>.

The bend for forming the second crease formed on the sheet P is inserted into the nip between the second conveying drive roller <NUM> and the second folding roller <NUM>. Thus, the sheet P is conveyed to the fourth conveyance path <NUM> in a state in which the second crease is formed on the sheet P as illustrated in <FIG>.

Thereafter, the sheet P on which the second crease is formed is discharged by the first discharge roller <NUM> and the second discharge roller <NUM> constituting the discharge roller section <NUM> as illustrated in <FIG>.

In some embodiments, as illustrated in <FIG>, the second sheet detector <NUM> may be replaced with a combination of a third conveying roller pair <NUM> and a second forward-reverse rotation sensor <NUM>. In this case, the third conveying roller pair <NUM> is rotated in reverse to convey the sheet P on which the first crease is formed in the direction opposite to the conveyance direction. When a predetermined time has elapsed since the leading end of the sheet P on which the first crease is formed is detected, the reverse rotation of the third conveying roller pair <NUM> is stopped. Thereafter, as illustrated in <FIG>, the third conveying roller pair <NUM> is rotated forward to form the second crease on the sheet P in the vicinity of the nip between the second conveying drive roller <NUM> and the second folding roller <NUM>.

<FIG> is a block diagram illustrating a control configuration of the image forming system <NUM> according to the present embodiment of this disclosure. As illustrated in <FIG>, the sheet processing unit <NUM> includes a central processing unit (CPU) 100a and a control circuit including a microcomputer having an input-output (I/O) interface 100b. The CPU 100a receives signals from the CPU 100a of the image forming unit <NUM>, each switch of the operation panel <NUM>, and the sheet detection sensors including the first sheet detector <NUM> and the second sheet detector <NUM>, via a communication interface 100c. The CPU 100a performs a predetermined control based on a signal input from the image forming unit <NUM>. The CPU 100a controls solenoids and motors including the drive motor <NUM>, via drivers and motor drivers for controlling the rotation direction and the rotation speed of the drive motor <NUM>, and acquires the data of the sheet sensors in the printer <NUM> via the communication interface 100c. Further, for example, the CPU 100a controls the drive control of the drive motor <NUM> by the motor driver via the I/O interface 100b with respect to the control object, and acquires the data from each sheet sensor. Note that the operation of the sheet processing unit <NUM> and the operation of the whole printer <NUM> are controlled by the CPU 100a reading program code stored in a read only memory (ROM) <NUM> and expanding the program code into a random access memory (RAM) <NUM>, and using the RAM <NUM> as a work area and a data buffer, and are performed based on the program defined in the program code.

In the present embodiment, the folding operation that can be performed by the folding mechanism illustrated in <FIG> is instructed and executed by the CPU 100a illustrated in <FIG>.

As described above, the drive transmission system of the sheet processing unit <NUM> according to the present embodiment includes a plurality of transmission paths of the first drive transmission path TP1 and the second drive transmission path TP2. The driving force transmitted in the first drive transmission path TP1 and the second drive transmission path TP2 is supplied from the drive motor <NUM>. The first drive transmission path TP1 is a transmission path that rotates the second conveyor <NUM> forward and rotates the first conveyor <NUM> forward. The second drive transmission path TP2 is a transmission path that rotates the second conveyor <NUM> in reverse and rotates the first conveyor <NUM> forward.

The reduction ratios of the drive systems in the two drive transmission paths TP1 and TP2 are adjusted and set, so that the conveying speed of the sheet P by the first conveyor <NUM> serving as the first conveying roller pair and the conveying speed of the sheet P by the second conveyor <NUM> serving as the second conveying roller pair can be adjusted.

For example, as illustrated in <FIG>, when the first conveyor <NUM> and the second conveyor <NUM> are rotated forward, a second conveyance speed V2 of the sheet P by the second conveyor <NUM> is not higher than a first conveyance speed V1 of the sheet P by the first conveyor <NUM>. When the second conveyor <NUM> is reversed while the first conveyor <NUM> rotates forward, a fourth conveyance speed V4 of the sheet P by the second conveyor <NUM> is not higher than a third conveyance speed V3 of the sheet P by the first conveyor <NUM>.

By adjusting as described above, the folding process can be performed without causing the sheet P to be pulled between the first conveyor <NUM> and the second conveyor <NUM> at any of the conveyance timings. The amount of bend of the sheet P between the first conveyor <NUM> and the second conveyor <NUM> can be controlled to a certain amount. As a result, the first crease can be accurately formed at a predetermined position on the sheet P.

In the second embodiment, for example, it is assumed that in the drive transmission path for transmitting the driving force to the first-conveying-roller-pair drive gear DG101, the total reduction ratio from the drive motor <NUM> to the second-conveying-roller-pair drive gear DG200 is <NUM>. In this case, the total reduction ratio of the path for transmitting the driving force from the drive motor <NUM> to the first-conveying-roller-pair drive gear DG101 via the drive transmission idler gear pulley GP103 is set to <NUM>. Accordingly, the first conveyance speed V1 can be set to be <NUM>% faster than the second conveyance speed V2. The third conveyance speed V3 is also <NUM>% faster than the fourth conveyance speed V4.

When the size of the sheet P to be folded is A4 size which is one of the specified sizes and the sheet P is folded in three-ply, the conveyance amount is about <NUM> to <NUM>. The bend generated during conveyance is <NUM> to <NUM>.

Assuming that the dimensional tolerance of the roller diameter of each roller constituting the first conveyor <NUM> and the second conveyor <NUM> is ± <NUM>, even if the roller pair of the first conveyor <NUM> has a negative tolerance and the roller pair of the second conveyor <NUM> has a positive tolerance, the relation of V1 ≥ V2 is always satisfied. Accordingly, the sheet P is not pulled between the first conveyor <NUM> and the second conveyor <NUM>.

As described above, the reduction ratio may be set in consideration of the specifications (e.g., compatible sizes) of the sheet processing unit <NUM> and the dimensional tolerance of each component so that the amount of bend of the sheet P formed between the first conveyor <NUM> and the second conveyor <NUM> does not exceed a certain amount during the conveyance of the sheet P.

Next, the operation control flows in the sheet processing unit <NUM> according to the first embodiment and the second embodiment are described with reference to the flowchart in <FIG> and <FIG>. The flowchart described below corresponds to the processing of the control program executed by the CPU 100a.

The sheet processing unit <NUM> receives the sheet P from the image forming unit <NUM> (S2601). Subsequently, the first conveyor <NUM> serving as the first conveying roller pair and the second conveyor <NUM> serving as the second conveying roller pair are rotated forward (S2602). Accordingly, the sheet P is conveyed from the first conveyance path <NUM> to the second conveyance path <NUM>.

Along with the conveyance of the sheet P, a determination process of whether the sheet sensor of the first sheet detector <NUM> detects the sheet P is performed (S2603). The conveyance of the sheet P continues until the sheet P is detected by the sheet sensor (S2603: NO). When the sheet sensor of the first sheet detector <NUM> detects the sheet P (S2603: YES), it is determined whether the sheet P has been conveyed by the designated length L (S2604).

The conveyance of the sheet P continues from the time when the sheet P is detected by the sheet sensor until the sheet P has been conveyed by the designated length L (S2604: NO). When the sheet P has been conveyed by the designated length L (S2604: YES), the second conveyor <NUM> is reversed. A bent portion of the sheet P is conveyed from the first conveyance path <NUM> to the third conveyance path <NUM> so that the sheet P is fold (S2605).

As illustrated in <FIG> and <FIG>, when the second sheet detector <NUM> includes the third conveying roller pair <NUM> and the second forward-reverse rotation sensor <NUM>, the operation control flow is as illustrated in the flowchart in <FIG>.

In this case, the process from receiving the sheet P from the image forming unit <NUM> to determining whether the sheet P has been conveyed by the designated length L and the subsequent process until the second conveyor <NUM> reversely conveys the sheet P are the same as the processes of S2601 to S2605 (S2701 to S2705).

Subsequently, a determination process is performed to determine whether the sheet P conveyed along the third conveyance path <NUM> is detected by the second forward-reverse rotation sensor <NUM> (S2706). The sheet P is conveyed in the third conveyance path <NUM> until the sheet P is detected by the second forward-reverse rotation sensor <NUM> (S2706: NO). When the second forward-reverse rotation sensor <NUM> detects the sheet P (S2706: YES), it is determined whether it is the timing of reversing the conveyance of the sheet P (S2707).

When it is the timing of reversing the conveyance of the sheet P (S2707: YES), the conveyance direction is switched again so that the sheet P is conveyed from the third conveyance path <NUM> to the fourth conveyance path <NUM> (S2708).

As described above, the sheet processing unit <NUM> according to the present embodiment exhibits an effect that both downsizing and cost reduction can be realized at the same time.

In the sheet processing unit <NUM> according to the present embodiment, a predetermined driving force is transmitted to the first conveying roller pair and the second conveying roller pair by the drive motor <NUM> (serving as the single driving force supply source) and a plurality of drive transmission paths. Thus, the device for folding the sheet P can be miniaturized.

In the sheet processing unit <NUM> according to the present embodiment, the first conveying roller pair is driven by receiving only the driving force from one side and the driving force in the opposite direction transmitted from each drive transmission path is cut off. Thus, the first conveying roller pair can be driven to rotate in the first direction (i.e., rotate forward) at any time.

In the sheet processing unit <NUM> according to the present embodiment, even though the rotation of each roller pair is controlled by the driving force supplied from the drive motor <NUM> serving as the single driving force supply source, the conveyance speed of an upstream portion of a sheet P is adjusted to be faster, thus preventing the sheet P from being pulled in opposite directions during conveyance.

In the sheet processing unit <NUM> according to the present embodiment, even if the rotation of each roller pair is controlled by the driving force supplied from the drive motor <NUM> serving as the driving force supply source, the conveyance speed of an upstream portion of the sheet P is adjusted to be faster, thus preventing the sheet P from being pulling from both sides during folding process.

In the sheet processing unit <NUM> according to the present embodiment, only the driving force in a certain direction can be transmitted by using the one-way clutch, thus allowing the conveying roller pair to appropriately receive the driving force from the two drive transmission mechanisms. This configuration can be achieved with a simple configuration that does not use an electromagnetic clutch or the like.

In the sheet processing unit <NUM> according to the present embodiment, a simple configuration and an arbitrary reduction ratio can be set depending on the number of teeth of the gears and the timing belt, and the conveyance speed of the sheet by the first conveying roller pair and the second conveying roller pair can be preferably set. Such a configuration can prevent the sheet P from being pulled in opposite directions by a plurality of conveying roller pairs both when the sheet P is conveyed and when the sheet P is folded.

Note that embodiments of the present disclosure are not limited to the specific embodiments described above, and numerous additional modifications and variations are possible in light of the teachings within the technical scope of the appended claims. It is therefore to be understood that the disclosure of this patent specification may be practiced otherwise by those skilled in the art than as specifically described herein, and such variations, modifications, alternatives are within the technical scope of the appended claims.

Claim 1:
A sheet processing apparatus (<NUM>) comprising:
a plurality of roller pairs configured to convey a sheet from upstream to downstream in a sheet conveyance direction, the plurality of roller pairs include:
a first roller pair (<NUM>);
a second roller pair (<NUM>) disposed downstream from the first roller pair in the sheet conveyance direction; and
a third roller pair (<NUM>) disposed between the first roller pair and the second roller pair and
configured to form a crease on the sheet; and
a single driving force supply source (<NUM>) configured to supply a driving force to the first roller pair (<NUM>), the second roller pair (<NUM>), and the third roller pair (<NUM>); the sheet processing apparatus (<NUM>) being characterized by
a drive transmission mechanism configured to transmit the driving force to the first roller pair (<NUM>) and the second roller pair (<NUM>) in a manner such that a rotation direction of the first roller pair (<NUM>) is not switched even in a case in which a direction of the driving force is switched such that a rotation direction of the second roller pair (<NUM>) is switched when the first roller pair (<NUM>) and the second roller pair (<NUM>) are driven by the driving force from the driving force supply source (<NUM>).