Patent ID: 7414645

Claim:
An image forming apparatus comprising: a photosensitive member that bears a latent image thereon and that defines a main scanning direction; and a scanning lens that transmits a light beam scanningly deflected in the main scanning direction for exposing the photosensitive member to the light beam to form the latent image thereon, the scanning lens comprising: a lens body formed of resin and extending substantially in the main scanning direction, the lens body defining a sub-scanning direction perpendicular to the main scanning direction and an optical-axis direction perpendicular both to the main scanning direction and to the sub-scanning direction, the lens body having opposite surfaces both being substantially perpendicular to the sub-scanning direction; and a rib formed integrally with the lens body and protruding in the sub-scanning direction from either one of the opposite surfaces, the rib extending over an entire effective scanning range in the main scanning direction, wherein a thickness of the rib in the optical-axis direction is less than a thickness of the lens body in the optical-axis direction within the effective scanning range.