Patent ID: 7631866

Claim:
A sheet processing apparatus comprising: a first folder to fold a sheet in a first folding direction relative to a given orientation of the sheet, a line of the fold defining a second edge of the sheet; a second folder to fold the folded sheet in a second folding direction perpendicular to the first folding direction; and a sheet aligner disposed between the first folder and the second folder, operable to switch a sheet conveyance direction of the sheet sent from the first folder and to align the sheet sent from the first folder, the sheet aligner including an aligning member arranged to face a first edge of the sheet, the first edge of the sheet being located relatively opposite to the second edge along the conveyance direction of the sheet, the second edge not having a straight line shape, a feeder to force the sheet in a given direction toward the aligning member so as to align the sheet in the sheet conveyance direction by contacting the first edge of the sheet against the aligning member, and a guide to move in accordance with a movement of a driven feed-back roller to guide the sheet toward the aligning member by contacting a top surface of the sheet, wherein the feeder includes a driving feed-back roller to face an under surface of the sheet, the driven feed-back roller to face the top surface of the sheet and a moving mechanism to move the driven feed-back roller upward and downward, the moving mechanism moves the driven feed-back roller upward to a standby position before the sheet aligner receives the sheet sent from the first folder and moves the driven feed-back roller downward to a pressing position at which the driven feed-back roller presses the sheet toward the driving feed-back roller so as to force the sheet toward the aligning member after the sheet aligner receives the sheet sent from the first folder.