Patent ID: 7857307

Claim:
A sheet accumulation apparatus, comprising: a sheet outlet for successively discharging sheets having images so that stitching margins of the sheets are oriented rearwardly, a tray member disposed under the sheet outlet for holding sheets therein, a sheet carrier member disposed above the tray member for discharging the sheets from the sheet outlet downstream thereof, a sheet front end regulating member for abutting the sheets sent by the sheet carrier member at front ends of the sheets, regulating the sheets and storing the sheets on the tray member, and a sheet rear end regulating member disposed with the tray member for regulating rear end positions of the sheets from the sheet outlet, wherein the sheet front end regulating member is comprised of two or more stopper members which include a first stopper member positioned on an upstream side and a second stopper member positioned on a downstream side in a sheet transferring direction for selectively facing sheet front end regulating positions, a shift member for driving the first and second stopper members, and a control member for controlling the shift member, and wherein the control member has a tabbed sheet discriminating member for discriminating whether or not the sheet from the sheet outlet has a tab projecting from the sheet front end, and when discriminating that the sheet from the sheet outlet has the tab by means of the tabbed sheet discriminating member, the control member causes the first stopper member positioned on the upstream side to retreat from the sheet regulating position, and causes the second stopper member to face the sheet front end regulating position, and when discriminating that the sheet from the sheet outlet does not have the tab by means of the tabbed sheet discriminating member, the control member causes the first stopper member to face the sheet regulating position.