Patent ID: 7924487

Claim:
An optical scanning device that is configured to scan a plurality of to-be-scanned surfaces with light beams, the optical scanning device comprising: a light source that includes a plurality of light emitting units for emitting light beams; a deflector that includes a deflecting surface for deflecting the light beams from the light source; a plurality of scanning optical systems that each correspond to one of the to-be-scanned surfaces and focus the light beams deflected by the deflector on corresponding one of the to-be-scanned surfaces; and a monitoring optical system that monitors a quantity of light beams emitted from the light source, wherein the light beams enter the deflector from a direction inclined with respect to a normal direction of the deflecting surface at least in a sub-scanning direction, and the light emitting units are arranged two-dimensionally, and a distance between two light emitting units at opposite ends in a main scanning direction is smaller than a distance between two light emitting units at opposite ends in the sub-scanning direction.