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.

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.

To provide a sheet stacking apparatus and image forming system capable of improving alignment characteristics also in the case where an aligning section is not able to act on a sheet discharged onto a stacking tray, the sheet stacking apparatus and image forming system include a stacking tray stacking discharged sheets, a pair of aligning sections capable of shifting in a width direction to align the width direction crossing a direction in which the sheet to stack on the stacking tray is discharged, and a control section that controls a relative position of the aligning sections and the sheet to discharge so that one of the pair of the aligning sections regulates a shift of the sheet stacked on the stacking tray to one direction side in the width direction, when a sheet with a predetermined width in the width direction of the sheet is discharged to the stacking tray.

To provide a sheet stacking apparatus and image forming system capable of improving alignment characteristics also in the case where an aligning section is not able to act on a sheet discharged onto a stacking tray, the sheet stacking apparatus and image forming system include a stacking tray stacking discharged sheets, a pair of aligning sections capable of shifting in a width direction to align the width direction crossing a direction in which the sheet to stack on the stacking tray is discharged, and a control section that controls a relative position of the aligning sections and the sheet to discharge so that one of the pair of the aligning sections regulates a shift of the sheet stacked on the stacking tray to one direction side in the width direction, when a sheet with a predetermined width in the width direction of the sheet is discharged to the stacking tray.

A sheet stacking apparatus includes a pair of sheet alignment mechanisms disposed to face each other in a direction of conveyance of a sheet or in a direction orthogonal to the direction of conveyance. Each one of the pair of sheet alignment mechanisms includes an aligning member, an elastic member, a driver, and a driving source. The aligning member reciprocates with reference to the sheet. The elastic member extends due to reaction force generated in response to pressing force applied to an edge of the sheet by the aligning member when a size of the sheet is larger than a prescribed size. The driver is coupled to the aligning member via the elastic member. The driving source transfers a driving force to the driver.

A sheet processing apparatus includes a buffering portion having a reverse conveyance roller pair and an intermediate roller pair, with the reverse conveyance roller pair reversing a conveyance direction of a sheet received from a first conveyance path and delivering the reversed sheet into a second conveyance path and being configured to come into contact with and be separated from each other. The intermediate roller pair is disposed in the second conveyance path and disposed upstream of a conveyance roller pair in a sheet conveyance direction, and the reverse conveyance roller pair is caused to nip a first sheet and a second sheet by causing the reverse conveyance roller pair to abut each other after receiving the second sheet by the reverse conveyance roller pair from the first conveyance path in a state in which the intermediate roller pair nips the first sheet reversed by the reverse conveyance roller pair and the reverse conveyance roller pair is separated from each other.

A sheet stacking device includes a pair of first sheet stackers, a pair of sheet alignment members, a second sheet stacker, a sheet removal portion, and control circuitry. The first sheet stackers stack both end portions of a sheet in a direction orthogonal to a sheet ejecting direction. The sheet alignment members contact both ends of the sheet in the orthogonal direction to align the sheet on the first sheet stackers. The second sheet stacker is disposed lower than the first sheet stackers and stacks the sheet dropped from between the first sheet stackers. The sheet removal portion is disposed on one side in the orthogonal direction. The control circuitry causes one of the first sheet stackers and one of the sheet alignment members to move toward an opposite side of the sheet removal portion in the orthogonal direction after the sheet is dropped from between the first sheet stackers.

A finisher assembly of a multifunction peripheral includes a vertically oriented stapler and a paper transport motor. When the paper transport motor rotates in the forward direction, printed pages from the print engine of the multifunction peripheral are received via a paper chute and a feed assist roller urges the printed pages into a vertical paper accumulation cache basin. Rotation of the paper transport motor also opens a biasing plate allowing the pages to freely enter the cache basin. Once all of the pages of the print job are in the cache basin, the paper transport motor rotates in the reverse direction causing the biasing plate to bias the printed pages, in the cache basin, against a registration surface of the vertically oriented stapler unit. The pages of the print job are stapled together the stapled print job is moved to the paper tray for collection by a user.

An image forming apparatus (1) includes a discharge port (25), a sheet stacking plate (41), a pair of cursors (43), a cursor driver (95), a pair of blowers (83) and a controller (37). Through the discharge port (25), a sheet formed an image is discharged. On the sheet stacking plate (41), the sheet discharged through the discharge port (25) is stacked. The pair of cursors (43) is supported on the sheet stacking plate (41) in a slidable manner in width directions perpendicular to a discharge direction of the sheet and comes into contact with both side edges of the sheet. The cursor driver (95) drives the pair of cursors (43). The pair of blowers (83) is provided in the pair of cursors (43) so as to blow air to both corners on an upstream side in the discharge direction of the sheet which is discharged through the discharge port (25), from above. The controller (37) controls the cursor driver (95) and the pair of blowers (83).

An image forming apparatus (1) includes a discharge port (25), a sheet stacking plate (41), a pair of cursors (43), a cursor driver (95), a pair of blowers (83) and a controller (37). Through the discharge port (25), a sheet formed an image is discharged. On the sheet stacking plate (41), the sheet discharged through the discharge port (25) is stacked. The pair of cursors (43) is supported on the sheet stacking plate (41) in a slidable manner in width directions perpendicular to a discharge direction of the sheet and comes into contact with both side edges of the sheet. The cursor driver (95) drives the pair of cursors (43). The pair of blowers (83) is provided in the pair of cursors (43) so as to blow air to both corners on an upstream side in the discharge direction of the sheet which is discharged through the discharge port (25), from above. The controller (37) controls the cursor driver (95) and the pair of blowers (83).