Patent ID: 7980544

Claim:
A sheet postprocessing apparatus comprising: a sheet table; sheet aligning means for aligning longitudinal and transverse positions of a sheet taken in onto the sheet table; a sheet hold flap arranged on an upper side of a vicinity of a rear end portion of the sheet table; a drive mechanism for switching the sheet hold flap to an initial position of separating the sheet hold flap from the table and a sheet hold position of making the sheet hold flap proximate to the table or bringing the sheet hold flap into contact therewith; and means for controlling a timing of returning the sheet hold flap to the initial position in accordance with a number of sheets on the sheet table, wherein the means delays a return start timing in accordance with an increase in the number of sheets, and makes a time period of from starting to take in the sheet to returning the sheet hold flap to the initial position constant regardless of the number of sheets on the sheet table.