Patent ID: 7380720
Filing Date: 2008-06-03
Classification: G06K

Abstract:
1. An optical scanning system, comprising: light source means having a plurality of light emitting portions; an optical deflector; an incident optical system for directing a plurality of light beams from said plurality of light emitting portions onto the same deflecting surface of said optical deflector, at different angles with respect to an optical reference axis perpendicular to the deflecting surface and with respect to a sub-scan sectional plane; and an imaging optical system for imaging the plurality of light beams deflected by said same deflecting surface of said optical deflector upon different scan surfaces, to be scanned, respectively; wherein said imaging optical system includes an imaging optical element, and the plurality of light beams deflected by said same deflecting surface of said optical deflector are incident on said imaging optical element so that the plurality of light beams pass through different regions of said imaging optical element with respect to the sub-scan sectional plane, respectively, wherein said imaging optical element has at least one optical surface defined, with respect to the sub-scan sectional plane, in accordance with different functions related to the different regions, respectively, wherein, when with respect to the sub-scan sectional plane the plurality of light beams incident on the same deflecting surface of said optical deflector have the same reflection point thereon, a meridional line of the optical surface of said imaging optical element defined in accordance with the function with respect to the sub-scan sectional plane, shifts in the sub-scan direction toward the same side, with respect to an optical reference axis which extends through the reflection point and is perpendicular to the deflecting surface, where the light beam passes, and wherein, when with respect to the sub-scan sectional plane the plurality of light beams incident on the same deflecting surface of said optical deflector have different reflection points on said same deflecting surface, a meridional line of the optical surface of said imaging optical element defined in accordance with the function with respect to the sub-scan sectional plane, shifts in the sub-scan direction toward the same side, with respect to an optical reference axis which extends through a middle point between two reflection points of all the different reflection points which tow points are most separate from each other and is perpendicular to the deflecting surface, where the light beam passes.