Patent ID: 7145590

Claim:
An image forming apparatus comprising: an image forming surface; a point light source array including a plurality of point light sources arranged in a line; and a lens array located between the image forming surface and the point light source array and including first and second rows of gradient index rod lenses, the lens array having a center line lying on a median plane between the first row of rod lenses and the second row of rod lenses, the point light sources being offset by a predetermined offset amount from a median position between the first row of rod lenses and the second row of rod lenses, the point light sources being asymmetrically offset with respect to an optical axis of the first row of rod lenses and an optical axis of the second row of rod lenses, and the center line being substantially parallel to a line connecting the point light source array to an image formed on the image forming surface, wherein the predetermined offset amount is in a range given by the equation: 0.5p×(X0/d)≦offset amount≦2.5p×(X0/d), where p is a pitch of the point light sources, X0 is a radius of a visual field of each of the gradient index rod lenses, and d is a lens interval between the gradient index rod lenses.