POST-PROCESSING DEVICE

PURPOSE:To correctly stack recording sheets on a sheet discharge tray by providing a vertically moving means vertically moving the sheet discharge tray and a control means detecting the removal of the recording sheets from the sheet discharge tray during the copying process and controlling the vertically moving means to move the sheet discharge tray to the normal sheet discharge position. CONSTITUTION:This post-processing device A is provided with a stapler unit 11 aligning the recording sheets image-formed by an image forming device and stapling the end sections, a sheet discharge tray 12 storing the bundles of stapled recording sheets, a discharge belt 10 discharging the bundles of the recording sheets to the sheet discharge tray 12 side, a discharge roller 3 receiving the bundles of the recording sheets discharged from the discharge belt 10 and discharging them onto the sheet discharge tray 12, and a detecting means detecting the height of the sheet discharge tray 12. The removal of the recording sheets from the sheet discharge tray 12 is detected during the copying process, and a vertically moving motor is controlled to move the sheet discharge tray 12 to the normal sheet discharge position. The tray 12 is invariably located at the sheet discharge position.