Patent ID: 8162303

Claim:
A sheet processing apparatus, comprising: a folding roller pair configured to fold a sheet or a sheet bundle by a nip portion and to convey a folded sheet or a folded sheet bundle; a sheet pushing member configured to perform a pushing operation in which a tip of the sheet pushing member pushes the sheet or the sheet bundle into the nip portion of the folding roller pair from a start position located away from the nip portion of the folding roller pair and to then perform a returning operation in which the tip returns to the start position; a detection unit configured to detect whether the tip of the sheet pushing member reaches a predetermined position in a moving direction of the sheet pushing member within a predetermined time elapsed after the sheet pushing member starts the pushing operation; and a control unit configured to control driving of the sheet pushing member and rotation driving of the folding roller pair according to a result of detection by the detection unit, wherein, in a case where the detection unit does not detect that the tip of the sheet pushing member reaches the predetermined position within the predetermined time, the control unit controls driving of the sheet pushing member such that the sheet pushing member retries the pushing operation after performing the returning operation, and in a case where the detection unit detects that the tip of the sheet pushing member reaches the predetermined position within the predetermined time, the control unit controls driving of the sheet pushing member such that the sheet pushing member stops the pushing operation and controls rotation driving of the folding roller pair such that the folding roller pair starts to convey the sheet or sheet bundle.