Patent ID: 8654172

Claim:
An optical scanning device, comprising: a plurality of light sources that emit light used as a plurality of optical scanning beams; an optical system disposed between the light sources and a light deflector, for receiving the optical scanning beams and configured such that the plurality of optical scanning beams strike a same face of the light deflector at different angles of incidence; the light deflector configured to deflect the plurality of optical scanning beams by the same face to optically scan a plurality of to-be-scanned portions simultaneously; and a single scan lens that receives the plurality of optical scanning beams from the light deflector, and focuses the plurality of optical scanning beams on the plurality of to-be-scanned portions to optically scan the plurality of to-be-scanned portions, wherein the single scan lens is used in common for the plurality of optical scan beams deflected by the same face of the light deflector, the single scan lens having at least one incidence plane at the face side of the light deflector and a plurality of exit planes at the to-be-scanned portions side, wherein a total number of incidence planes is different than a total number of exit planes, each exit plane is separately formed in a sub-scanning direction for each of the to-be-scanned portions, and the exit planes of the single scan lens are formed as a face having positive refractive power both in the main scanning direction and sub-scanning direction.