Abstract: A sheet processing apparatus including a sheet feeder, a sheet processing device, a sheet ejection device, a purge unit, a multifeed sensor, and circuitry. The sheet feeder feeds a sheet toward a sheet conveyance passage. The sheet processing device performs a predetermined operation on the sheet. The sheet ejection device stacks the sheet when the predetermined operation has been performed. The purge unit stacks the sheet when the predetermined operation has not been performed. The multifeed sensor detects whether sheets are multifed and a number of multifed sheets. The circuitry counts a number of sheets, determines that the sheets stacked in the purge unit is full when a number of counted sheets reaches a predetermined number of sheets, and conveys the multifed sheets toward the purge unit and adds the number of counted sheets according to the number of multifed sheets, in response to detection of the multifed sheets.

Abstract: A sheet feeder includes a sheet stacker, a sheet feed roller, a separation roller pair, and a lifter. Sheets are conveyed and stacked on the sheet stacker. The sheet feed roller feeds the sheets. The separation roller pair separates the sheets fed by the sheet feed roller one by one. The lifter lifts and lowers the sheet stacker depending on a stack amount of the sheets. The sheet stacker includes a first stacking face, a second stacking face, and a bent portion integrally connecting the stacking faces such that the stacking faces form a specified angle. The sheet stacker stacks the sheets such that a center of gravity of the sheets is positioned above the first stacking face and integrally displaces the stacking faces when the lifter operates.

Abstract: A sheet processing device includes a sheet storage and a sheet displacer. The sheet storage includes a first storage portion that includes a first wall that is one side wall of the sheet storage and a second wall that is part of another side wall of the sheet storage and a second storage portion that includes a third wall continuous to the first wall and the second wall. The sheet displacer displaces a preceding sheet stored in the sheet storage and contacts an upper end of the preceding sheet to displace the preceding sheet such that the upper end of the preceding sheet moves toward the third wall. The second wall and the third wall are coupled via a bent portion that bends in a manner such that a storage space of the second storage portion is greater than a storage space of the first storage portion.

Abstract: A sheet separation device that conveys a two-ply sheet in a state where the one side joined is located on an upstream side or a downstream side of the two-ply sheet in a conveyance direction, separates the two-ply sheet into the two sheets, and inserts an inner sheet from a non-joined side opposite the joined side in the sheet conveyance direction so that the inner sheet is sandwiched between the two sheets overlaid with each other includes a conveying roller pair including a pair of rollers and circuitry. The conveying roller pair conveys the two-ply sheet and holds a joined portion of in the two-ply sheet at which the two sheets are joined, at a nip portion of the conveying roller pair when the inner sheet is inserted into the two-ply sheet. The circuitry contacts the inner sheet against the joined portion of the two-ply sheet to perform skew correction.

Abstract: A sheet processing apparatus including a sheet feeder, a sheet processing device, a sheet ejection device, a purge unit, a multifeed sensor, a sheet sensor, and circuitry. The circuitry stops an operation of the sheet processing apparatus when the multifeed sensor has not detected multifeed of the sheet and the sheet sensor does not detect a trailing end of the sheet after a first set time from detection of a leading end of the sheet, stop the operation when the multifeed sensor has detected the multifeed and the sheet sensor does not detect the trailing end of the sheet after a second set time from the detection, and conveys the sheet toward the purge unit without stopping the operation when the multifeed sensor has detected the multifeed and the sheet sensor detects the trailing end of the sheet before the second set time elapses from the detection.