Patent attributes
The optical scanning device includes a light source emitting multiple light beams; an optical deflecting device having a reflection surface on which the light beams are incident to be reflected while deflected; multiple scanning optics systems focusing the light beams on the surfaces of members to be scanned while scanning the surfaces with the light beams in a main scanning direction; and multiple glass plates located between the multiple scanning optical systems and the members on the light paths while slanted and having no refracting power in the main and sub-scanning scanning directions. The light beams include two or more light beams having different incidence angles in the sub-scanning direction relative to the normal line of the reflection surface of the optical deflecting device, and the slanting angles of the glass plates are determined depending on the incidence angles of the corresponding light beams passing through the glass plates.