Patent ID: 8302964

Claim:
A sheet stacking apparatus comprising: a plurality of sheet stacking units including at least a first sheet stacking unit and a second sheet stacking unit on which a sheet is stacked; a sheet discharging portion configured to discharge the sheet on one of the plurality of sheet stacking units selectively, the sheet discharging portion including: a plurality of discharging rotary members including at least a first discharging rotary member and a second discharging rotary member arranged in a sheet discharging direction and a movable rotary member, movable along the sheet discharging direction to selectively, form a nip with the first discharging rotary member to nip and discharge the sheet to the first sheet stacking unit and form a nip with the second discharging rotary member to nip and discharge the sheet to the second sheet stacking unit; and a controller which controls the movable rotary member so that the position of the movable rotary member is changed along the sheet discharging direction to a position of the selected first or second discharging rotary member to discharge the sheet to the corresponding first or second sheet stacking unit.