Patent ID: 7505187

Claim:
An optical scanning unit that irradiates a polygon mirror with a plurality of light beams emitted from a light source according to image data, the optical scanning unit converting the plurality of light beams to scanning lights by the rotation of the polygon minor, the optical scanning unit scanning and exposing a plurality of photoreceptors simultaneously with the plurality of scanning lights to form latent images on the respective photoreceptors, the optical scanning unit comprising: a chassis having a cylindrical lens that makes the light beam for exposing the photoreceptor converge on the surface of the photoreceptor, wherein the cylindrical lens is supported by two support portions for the chassis such that the longitudinal direction of the cylindrical lens becomes parallel to the scanning direction of the photoreceptor and the optical scanning unit is configured such that the angle of the cylindrical lens in the longitudinal direction is adjustable in the sub-scanning direction of the photoreceptor at one of the support portions by an eccentric cam.