Patent ID: 7766314

Claim:
A sheet post-processing apparatus comprising: a process tray which stacks a sheet thereon; a storage tray which stacks the sheet discharged from the process tray thereon; a paper discharge roller which is provided at the end of the process tray in a sheet discharging and conveying direction to discharge the sheet to the storage tray; a bundle hook which is provided in a bundle discharge belt rotating in the sheet discharging and conveying direction of the process tray to discharge and convey the sheet stacked on the process tray in the storage tray direction; and a driving source configured to decelerate a tangential speed at which the paper discharge roller discharges the sheet and a movement speed of the bundle hook from a first movement speed to a second movement speed at which the bundle hook discharges and conveys the sheet in accordance with a rotation position of the bundle hook so that the second movement speed of the bundle hook is slower than the tangential speed of the paper discharge roller during a sheet stacking operation in which the bundle hook passes from a discharge start position of the sheet to a sheet rear end contacting member of the process tray, wherein, when the bundle hook passes from the sheet rear end contacting member and returns to a home position, the movement speed of the bundle hook is set at a fourth movement speed which is faster than the second movement speed and slower than the first movement speed.