Patent ID: 6839156

Claim:
A laser scanning unit for an electrophotographic image forming apparatus comprising: a plurality of photosensitive media; a driving unit having a rotation shaft; a plurality of photogenerators emitting parallel beams; a plurality of rotatable polygonal mirrors which deflect the beams emitted from the photogenerators in a main scanning direction having a range of a predetermined angle to scan the beams onto corresponding ones of the photosensitive media proceeding in a sub scanning direction, the rotatable polygonal mirrors stacked on the driving unit to match corresponding ones of the photogenerators and coupled with the rotation shaft of the driving unit to rotate therewith; a plurality of first lenses which are installed in light paths of the beams between the photogenerators and the rotatable polygonal mirrors, respectively, and collect the beams in the sub scanning direction; and a plurality of second lenses which collect the beams deflected by corresponding ones of the rotatable polygonal mirrors on corresponding ones of the photosensitive media.