Arrangement of vertices of curved surface of imaging lens for correcting scanning line curvature

摘要

An optical scanning device of an electrophotographic printer is provided. The optical scanning device includes an optical source portion to emit an optical beam inclined in a sub-scanning direction with respect to a reference plane, an optical deflector to deflect and scan the optical beam in a main scanning direction, and an imaging lens to image the deflected optical beam onto a light-exposed object and having an optical axis which is parallel to the reference plane. In order to correct a scanning line curvature, a location of a vertex of a curved surface of the imaging lens in the sub-scanning direction is varied based on a location in the main scanning direction.