Patent ID: 7633663

Claim:
An optical scanning device, comprising: a light deflector configured to deflect light beams from at least one of a plurality of light source devices in a main scanning direction; and at least one scanning focus lens having a surface with a curvature in a sub-scanning direction that is orthogonal to the main scanning direction, such that the curvature changes in such a way as to increase negative power over an entirety of the surface as an image height increases, the curvature being either one of zero and substantially zero on a reference axis of the at least one scanning focus lens, wherein the light beams are made incident on a deflective reflection surface of the light deflector at an angle in a sub-scanning direction with respect to a normal of the deflective reflection surface, and the optical scanning device is configured to focus the light beams deflected by the light deflector on a surface to be scanned, and wherein the at least one scanning focus lens is disposed closer to the light deflector than another scanning focus lens having a largest refracting power in the sub-scanning direction.