US Patent 7468823 Optical beam scanning device, image forming apparatus and lens

An optical beam scanning device of the invention includes a single light deflection device, a pre-deflection optical system which causes a light beam emitted from a light source to be incident to the light deflection device, and a post-deflection optical system which images the light beam, reflected from the light deflection device, onto a scanned surface. In the optical beam scanning device, an alignment surface to which the lens is fitted is located near a main scanning direction line passing through a midpoint of a maximum section thickness of the lens in at least one lens in one or the plurality of lenses constituting the post-deflection optical system.