Patent ID: 7663790

Claim:
An apparatus comprising an optical multi-beam scanning device, wherein the optical multi-beam scanning device includes: a plurality of light sources; a deflecting device configured to deflect light beams from the plurality of light sources; a post-deflection optical system configured to make the light beams deflected by the deflecting device enter a surface to be scanned in a vertical scanning direction with respect to a normal direction of the surface to be scanned at a predetermined angle; a horizontal synchronization sensor configured to synchronize the light beams in a horizontal scanning direction; an optical path folding device configured to fold the light beams, directing towards the surface to be scanned, to the horizontal synchronization sensor; and a light shielding member having a tilt such that if the light beams reach the surface to be scanned without being folded by the optical path folding device, the light beams will be emitted to a light receiving surface of the horizontal synchronization sensor with a uniform rate when the light beams come to the same position on the surface to be scanned.