Patent ID: 8820736

Claim:
A sheet post-processing apparatus comprising: a sheet discharge path having a carry-in entrance and a sheet discharge outlet; a transport roller disposed in the sheet discharge path; a processing tray disposed below the sheet discharge outlet with a height difference formed; a back transport path for reversing a transport direction of a sheet to transport from the sheet discharge path to the processing tray; sheet discharge rollers disposed in the sheet discharge outlet to carry the sheet fed from the carry-in entrance to the back transport path: sheet guide means for guiding the sheet fed by the sheet discharge rollers to the processing tray so as to form the back transport path; post-processing means disposed in the processing tray; sheet side edge alignment means disposed in the processing tray to align a width-direction position of the sheet with a beforehand set reference line; and a common drive motor, wherein the sheet guide means is comprised of a pair of right and left guide members having guide surfaces capable of shifting to positions in a carry orthogonal direction of the sheet carried to the processing tray, the sheet side edge alignment means is comprised of a pair of right and left side edge alignment members having alignment surfaces for sheet side edges capable of shifting to positions in a sheet-discharge orthogonal direction of the sheet, and the common drive motor is configured to shift the guide members and the side edge alignment members to positions in the sheet-discharge orthogonal direction in an integral manner.