A sheet processing includes a first conveyance path, a buffering portion, a second conveyance path, a conveyance roller pair, a supporting portion, a moving member, a regulating portion, and a processing unit. The buffering portion is configured to superimpose a first sheet and a second sheet on each other in a state of being offset from each other in a sheet conveyance direction. An offset amount, by which a leading end of the first sheet in the sheet conveyance direction projects downstream in the sheet conveyance direction with respect to a leading end of the second sheet in the sheet conveyance direction in a state before the first sheet and the second sheet are discharged onto the supporting portion, is larger than a distance from a sheet contact position of the moving member to the regulating portion in the sheet conveyance direction.

A sheet binding unit includes a first sheet binder having first and second dentate uneven sheet binding elements to conduct a first sheet binding process by engaging each other by a prescribed meshing depth while sandwiching the sheet bundle therebetween to form a dentate unevenness on the sheet bundle at a first sheet binding portion of the sheet bundle, and a second sheet binder having third and fourth dentate uneven sheet binding elements to conduct a second sheet binding process by engaging each other by a greater meshing depth than that made by first and second dentate uneven sheet binding elements of the first sheet binder while sandwiching the sheet bundle therebetween to form a dentate unevenness on the sheet bundle at a second sheet binding portion different from the first sheet binding portion of the sheet bundle.

A sheet binding unit includes a first sheet binder having first and second dentate uneven sheet binding elements to conduct a first sheet binding process by engaging each other by a prescribed meshing depth while sandwiching the sheet bundle therebetween to form a dentate unevenness on the sheet bundle at a first sheet binding portion of the sheet bundle, and a second sheet binder having third and fourth dentate uneven sheet binding elements to conduct a second sheet binding process by engaging each other by a greater meshing depth than that made by first and second dentate uneven sheet binding elements of the first sheet binder while sandwiching the sheet bundle therebetween to form a dentate unevenness on the sheet bundle at a second sheet binding portion different from the first sheet binding portion of the sheet bundle.

A sheet processing apparatus arranged in a space between an image reading section for reading an image and an image formation section for forming an image on a sheet includes a carry-in path guiding a sheet from a carry-in entrance; a relay roller provided in the carry-in path to relay and transport the sheet; a first transport path positioned on a downstream side of the relay roller and having a carry-in roller to transport the sheet from the carry-in path to the first collection tray; and a second transport path branched from the carry-in path and having a branch roller to transport the transported sheet to the second collection tray. The relay roller shifts the sheet in a direction crossing the transport direction while a front end of the sheet enters the first transport path or the second transport path, and arrives at the carry-in roller or the branch roller.

A sheet processing apparatus arranged in a space between an image reading section for reading an image and an image formation section for forming an image on a sheet includes a carry-in path guiding a sheet from a carry-in entrance; a relay roller provided in the carry-in path to relay and transport the sheet; a first transport path positioned on a downstream side of the relay roller and having a carry-in roller to transport the sheet from the carry-in path to the first collection tray; and a second transport path branched from the carry-in path and having a branch roller to transport the transported sheet to the second collection tray. The relay roller shifts the sheet in a direction crossing the transport direction while a front end of the sheet enters the first transport path or the second transport path, and arrives at the carry-in roller or the branch roller.

Provided are a post-processing apparatus, an image forming apparatus, and a post-processing method capable of avoiding the occurrence of a malfunction due to a failure to discharge a sheet bundle after a binding process. A plurality of sheets is loaded on a stack tray. A staple unit binds the plurality of sheets. A discharge roller discharges the sheet bundle bound by the staple unit from the stack tray. Each time a sheet is conveyed to the stack tray, an aligning unit moves between a first position in contact with the sheet loaded on the stack tray and a second position separating from the sheet. A detection processing unit detects a failure of discharging the sheet bundle by the discharging roller. A stop processing unit can stop the operation of the aligning unit when the discharge failure is detected by the detection processing unit.

A sheet post-processor includes a processing tray, a sheet discharge port, a discharge roller pair, a pair of cursor members, a pair of support members, and an interlocking mechanism. The interlocking mechanism includes a pair of coupling members arranged in the processing tray so as to be reciprocatable in a sheet width direction. The pair of coupling members are coupled to or decoupled from the pair of cursor members in accordance with movement of the pair of cursor members. While being coupled to the pair of cursor members, the pair of coupling members contact the pair of support members so as to displace the pair of support members to a protruding position, and while being decoupled from the pair of cursor members, the pair of coupling members separate from the pair of support members so as to displace the pair of support members to a retracted position.

A sheet processing apparatus includes a conveyance member to convey a sheet, a pair of alignment members to move relatively in a width direction orthogonal to a conveyance direction of the sheet by the conveyance member, so as to align a position of the sheet in the width direction, and a lower portion to support a lower surface of the sheet between the pair of alignment members in the width direction. In addition, a pair of upper portions are arranged on one side and the other side of the lower portion in the width direction and each hold an upper surface of the sheet, wherein the pair of upper portions is positioned lower than the lower portion in a plane vertical to the conveyance direction.

A sheet processing apparatus includes a conveyance member to convey a sheet, a pair of alignment members to move relatively in a width direction orthogonal to a conveyance direction of the sheet by the conveyance member, so as to align a position of the sheet in the width direction, and a lower portion to support a lower surface of the sheet between the pair of alignment members in the width direction. In addition, a pair of upper portions are arranged on one side and the other side of the lower portion in the width direction and each hold an upper surface of the sheet, wherein the pair of upper portions is positioned lower than the lower portion in a plane vertical to the conveyance direction.

In order to properly suppress a discharge defect corresponding to an image ratio of a sheet, in the case where a coefficient of friction is different according to the image ratio of an image on the sheet, an air blowing section is arranged to blow air toward a downstream side in a transport direction from between a downstream-side end portion of a first stacking section and an upstream-side end portion of a second stacking section. When an image ratio of an image on a sheet by an image forming apparatus is a first value, the air blowing section sets an air quantity blown to the sheet at a first air quantity F1, while when the image ratio is a second value higher than the first value, setting the air quantity blown to the sheet at a second air quantity F2 larger than the first air quantity F1.