SHEET STACKING DEVICE, SHEET POST-PROCESSING DEVICE AND IMAGE FORMING APPARATUS PROVIDED WITH SHEET POST-PROCESSING DEVICE

摘要

A controller of a sheet stacking device executes tray elevating processing and sheet stacking processing. The tray elevating processing is processing in which when a sensor detects an uppermost sheet, the controller once lowers a stacking tray, and lifts the stacking tray until the sensor detects the uppermost sheet. The sheet stacking processing is processing in which the controller arranges a guide arm at an advanced position to guide the sheet, arranges the guide arm at a retracted position before a rear end of the sheet passes the sheet discharge portion, and stacks the sheet on the stacking tray after the rear end of the sheet passes the sheet discharge portion. The controller executes the tray elevating processing in a state where the guide arm is disposed at the advanced position during the execution of the sheet stacking processing.