US Patent 7283288 Scanning device

According to an aspect of the invention, there is provided a scanning device, which is provided with a light source unit that emits a light beam, a collection optical system that converges the light beam emitted by the light source unit principally in an auxiliary scanning direction, a deflector that deflects the light beam converged by the collection optical system, an image forming optical system that converges the light beam deflected by the deflector onto a scan target surface to form a beam spot scanning in a main scanning direction which is perpendicular to the auxiliary scanning direction. In this configuration, the scanning device satisfies a following condition:−1<S1−S2<1   (A)where