Patent ID: 7198261

Claim:
A sheet stacking apparatus comprising: a first sheet stacking device that stacks sheets; a first discharging device that discharges a sheet conveyed from an upstream side thereof toward said first sheet stacking device; a second sheet stacking device provided downstream of said first sheet stacking device, wherein a leading end of a sheet laid on said second sheet stacking device is lower in level than a highest portion of a trailing end thereof laid on said first sheet stacking device when the trailing end of the sheet is discharged from said first discharging device; a second discharging device that discharges the sheets stacked on said first sheet stacking device to said second sheet stacking device, said second discharging device being capable of selectively assuming a catching state in which a sheet discharged to said first sheet stacking device is caught by said second discharging device, and a non-catching state in which a sheet discharged to said first sheet stacking device is not caught by said second discharging device; a pivotal aligning wall member that aligns the trailing ends of the sheets stacked on the second sheet stacking device; and a controller that controls said second discharging device to assume the non-catching state when said first discharging device starts discharging a sheet, and to switch to the catching state before a trailing end of the sheet discharged by said first discharging device passes said second discharging device.