Patent ID: 7549621

Claim:
A sheet post-processing apparatus for applying a specified post-processing to sheets successively received from an upstream apparatus into an apparatus main body, comprising: a discharge tray onto which the sheets having passed through the apparatus main body are discharged, the discharge tray being movable upward and downward between a specified home position, an upper position located above the home position, and a lower position located below the home position, an elevating mechanism for moving the discharge tray upward and downward, a position sensor disposed for detecting a leading end and a trailing end of a sheet about to be discharged onto the discharge tray, and a control unit operatively connected to the elevating mechanism and the position sensor for controlling upward and downward movements of the elevating mechanism in synchronism with the sheet discharge onto the discharge tray, wherein the discharge tray is caused to move from the home position to the upper position in synchronism with an arrival timing of the leading end of a first sheet being discharged at the discharge tray, the discharge tray is caused to move from the upper position to the lower position in synchronism with an arrival timing of the leading end of a succeeding sheet at the discharge tray, and the discharge tray is caused to receive the succeeding sheet while being caused to move from the lower position to the upper position, during the discharge of the succeeding sheet onto the discharge tray.