Patent ID: 7782511

Claim:
An optical scanning apparatus comprising: a light source adapted to emit a light beam; a light deflection unit adapted to deflect the light beam emitted from the light source in a main scanning direction; an electro-optical crystal member, which is provided in an optical path of the light source, adapted to deflect the light beam emitted from the light source in a sub-scanning direction by a voltage applied to the electro-optical crystal member; and a plurality of light detection units adapted to detect the light beam deflected in the sub-scanning direction by the electro-optical crystal member, wherein the electro-optical crystal member selectively deflects the light beam to at least one of a first optical path where a photosensitive member is provided or a second optical path where the plurality of light detection units are provided, the first and second optical paths being different in the sub-scanning direction, wherein the plurality of light detection units are arranged within an image forming region, in the main scanning direction, corresponding to an electrostatic latent image formed on the photosensitive member, and wherein outputs of the plurality of light detection units are used to control an irradiation position of the light beam on the photosensitive member in the main scanning direction.