Patent ID: 7503556

Claim:
A sheet finisher comprising: a push-in member to push a sheet bundle; a pair of rollers to fold the sheet bundle pushed-in by the push-in member; a movement member to move at least one roller of the pair of rollers; an acquiring member to acquire information of a thickness of the sheet bundle; and a control member to control the movement member so as to adjust a clearance between the pair of rollers, based on the information of the thickness of the sheet bundle acquired by the acquiring member; a drive member to drive the push-in member; and a measurement member to measure a consumption current of the drive member; wherein the acquiring member comprises: a detection unit to detect the thickness of the sheet bundle from a correspondence table of consumption currents and sheet bundle thicknesses, based on the consumption current measured by the measurement member; and wherein the control member controls the movement member so as to adjust the clearance between the pair of rollers, based on the thickness of the sheet bundle acquired by the acquiring member.