Patent ID: 8226080

Claim:
A sheet post-processing apparatus for collating and collecting sheets fed from an image formation apparatus to performing post-processing, comprising: a sheet discharge outlet; tray means for loading and collecting a sheet fed from the sheet discharge outlet; sheet end regulation means provided on the tray means to regulate an end edge of the sheet; a sheet discharge rotating body for transferring the sheet that is carried out onto the tray means toward the sheet end regulation means; lifting/lowering support means for supporting the sheet discharge rotating body to able to move up and down between an operation position coming into contact with the sheet on the tray means and a withdrawal position separated from the sheet; lifting/lowering driving means for driving the lifting/lowering support means; and lifting/lowering control means for controlling the lifting/lowering driving means, wherein the lifting/lowering control means is configured is to be able to adjust operation timing of shifting the sheet discharge rotating body to the operation position from the withdrawal position corresponding to image formation conditions of the sheet.