Patent ID: 8511679

Claim:
A sheet processing device for stacking sheets on a stack tray at a transversely offset position with respect to a sheet transporting direction, comprising: an offset transport unit configured to eject sheets onto the stack tray while the sheets remain in the offset position; a first sheet lineup unit configured to line up the sheets in the sheet transporting direction; and a second sheet lineup unit configured to line up the sheets in a direction perpendicular to the sheet transporting direction, wherein the first sheet lineup unit includes a stopper that engages leading edges of the sheets ejected onto the stack tray from the offset transport unit and a drive unit configured to adjust a position of the stopper, the second sheet lineup unit includes a pair of joggers configured to jog the sheets ejected by the offset transport unit onto the stack tray to the offset position, and a pair of sheet fences configured to engage the sheets to be jogged by the pair of joggers into the offset position, the pair of sheet fences are disposed inside the pair of joggers and are pivotally supported by support members at upper ends thereof, one of the pair of sheet fences corresponding to a side on which the sheets are ejected from the offset transport unit rotates upwardly by being pushed by an upper surface of the sheets ejected from the offset transport unit while the sheets remain in the offset position, and a jogger on a side of the sheet fence that rotates upwardly by being pushed by the upper surface of the sheets between the pair of joggers makes contact with ends on one side of the sheets that are ejected and jogs the sheets to the offset position, and ends on other side of the sheets are brought into contact with the other sheet fence so that the offset position of the sheets is engaged.