| 摘要 |
A multi-beam optical scanning device includes a light source device, a deflector for deflecting a plurality of light beams from the light source device, and an imaging optical system for imaging a plurality of light beams deflected by the deflector upon a photosensitive drum, wherein a plurality of light beams, when they pass through an imaging optical element having a largest positive power in the sub-scan direction, pass through positions which are spaced apart from each other in the sub-scan direction, and wherein the photosensitive drum is so disposed that, when, among the plurality of light beams passing through the imaging optical element having a largest positive power in the sub-scan direction, a light beam which passes through a position furthermost in the sub-scan direction from a meridional of the imaging optical element having a largest positive power in the sub-scan direction is incident on the photosensitive drum, an incidence angle thereof in the sub-scan direction with respect to a surface normal of the photosensitive drum becomes smallest as compared with the other light beam or beams. |
