| 摘要 |
PROBLEM TO BE SOLVED: To provide a multibeam scanning optical system capable of reducing a main scanning jitter and having a returning light reducing effect. SOLUTION: The surface of a photoreceptor drum is nearly perpendicular to the symmetric axis of an fθlens but a paraxial image surface is inclined. Light fluxes A and B at both ends in the main scanning direction are temporarily crossed on the paraxial image surface. The surface of the drum is irradiated with the light fluxes based on mutual positional relation in accordance with the positional relation of the drum and the paraxial image surface. The reaching positions of the respective light fluxes are replaced at both ends in the main scanning direction and the flux A is always positioned on the outside. The image surface is constituted to be inclined in such a way, and the off-axis aberration of the fθlens is adjusted so as to always constitute a minimum spot on the surface of the drum separately from the paraxial image surface. Namely, a main light beam crosses and its position is changed on the paraxial image surface, and it is defocused from the surface of the drum. |
