Patent ID: 7728863

Claim:
An optical scanning device comprising: a light source; a deflecting unit configured to deflect a light beam from the light source; and a scanning and imaging optical system including at least two scanning lenses and configured to guide the light beam deflected by the deflecting unit to a surface to be scanned, wherein: one of the scanning lenses which is closest to the deflecting unit has a positive refractive power in a main scanning direction and zero or approximately zero refractive power in a sub scanning direction, another one of the scanning lenses which is closest to the surface to be scanned has a negative refractive power in the main scanning direction, a positive refractive power in the sub scanning direction, and an incidence surface in the sub-scanning direction which is convex toward the deflecting unit and an exit surface being concave toward the surface to be scanned, the optical scanning device comprising a plurality of light sources including said light source, the deflecting unit is configured to deflect a plurality of light beams from the plurality of light sources, the scanning and imaging optical system is configured to guide the light beams to different surfaces to be scanned, and the light beams directed to the different surfaces to be scanned pass through the one of the scanning lenses which is closest to the deflecting unit approximately in parallel with each other in the sub scanning direction.