Patent ID: 8120830

Claim:
An optical scanning apparatus for scanning a rotating photosensitive member with a light beam deflected by a rotatable polygonal mirror, said optical scanning apparatus comprising: a first light source for outputting a first light beam; a second light source for outputting a second light beam; a third light source for outputting a third light beam; a first optical unit for adjusting a distance between imaging positions of the first light beam and the second light beam to a predetermined distance with respect to a rotational moving direction of the photosensitive member, wherein said first optical unit is rotatable to adjust the imaging positions of the first light beam and the second light beam; and a second optical unit for adjusting an imaging position of the third light beam relative to the first light beam and the second light beam, the distance between which is adjusted to the predetermined distance, with respect to the rotational moving direction of the photosensitive member, wherein said second optical unit is rotatable to adjust the imaging position of the third light beam relative to the imaging positions of the first light beam and the second light beam, wherein said second optical unit is rotatable independently of said first optical unit, and wherein by rotational adjustment of said second optical unit, the third light beam can be imaged between the first light beam and the second light beam with respect to the rotational moving direction of the photosensitive member, or the first light beam and the third light beam can be imaged at positions across the second light beam from each other with respect to the rotational moving direction of the photosensitive member.