Patent ID: 7333767

Claim:
A paper post-processing apparatus for punching a paper to make at least one hole in the paper, said apparatus comprising: a punching unit which includes at least one punch; a transporting roller system which nips and transports the paper, the transporting roller system comprising a driving roller and a driven roller arranged downstream of the punching unit in a paper transport direction; an urging member which urges the driven roller to come into pressure contact with the driving roller; an actuator which, when activated, releases the driven roller from the pressure contact with the driving roller against an urging force exerted by the urging member; an aligning unit which aligns the paper in a width direction thereof that is perpendicular to the paper transport direction; and a stopper member arranged upstream of the at least one punch of the punching unit in the paper transport direction, the stopper member being insertable into and removable from a paper transport path; wherein, when the paper is to be punched by the punching unit: (i) the transporting roller system nips and transports the paper while the stopper member is removed from the paper transport path; (ii) the actuator is activated to end nipping of the paper by the transporting roller system after at least a leading edge portion of the paper has passed through the punching unit; (iii) the aligning unit aligns the paper in the width direction thereof; (iv) the actuator is deactivated to resume the nipping of the paper by the transporting roller system; (v) the paper is transported while the stopper member is inserted into the paper transport path such that a trailing edge of the paper hits the stopper member; and (vi) the punching unit punches the paper.