Image forming apparatus having two-beam optical scanning unit with movable laser beam emitters and separate dynamic and precision adjusting of laser beams

摘要

An image forming apparatus, such as a copying machine or a printer having a two-beam optical scanning unit, includes a pair of semiconductor laser beam emitters, each emitter generating a respective laser beam. A beam composition prism composes the two laser beams and a photoreceptor is provided for holding an image written with the two laser beams. A defector deflects the two laser beams onto the photoreceptor in a primary scanning direction so that the two laser beams are emitted on a primary scanning plane. Two supporting members each respectively supports one of the pair of semiconductor laser beam emitters. A moving member is provided for moving at least one of the two supporting members so that at least one of the two laser beams is movably adjusted so as to have a predetermined emitting direction.