Patent ID: 8100400

Claim:
A sheet ejecting device for ejecting printed sheets along a sheet ejection route to a stacker one by one, said sheet ejecting device comprising: a pair of ejection rollers for ejecting a sheet; a strengthener, arranged above the sheet ejection route, and arranged to be capable of advancing into and retreating from the sheet ejection route, for strengthening a sheet; a driver for moving the strengthener to advance into and retreat from the sheet ejection route; a sensor for detecting a currently ejected sheet; and a controller for controlling the driver based on a signal sent from the sensor; wherein the controller controls the driver so that the strengthener advances into the sheet ejection route from above the sheet ejection route and so that the strengthener retreats from the sheet ejection route to a location above the sheet ejection route at a time after a leading edge of the currently ejected sheet comes into contact with a stack of sheets on the stacker and before a trailing edge of the sheet passes the pair of ejection rollers.