Patent ID: 6137617
Filing Date: 2000-10-24
Classification: G02B

Abstract:
An optical scanner, comprising:a light source;an optical deflector for scanning a light beam from the light source;a first imaging optical system for forming a line image on a deflecting plane of the optical deflector, the first imaging optical system being positioned between the light source and the optical deflector; anda second imaging optical system formed of one correcting lens, the second imaging optical system being positioned between the optical deflector and a surface to be scanned,the first imaging optical system being positioned in a plane parallel to a main scanning direction including the normal line of the deflecting plane of the optical deflector and being formed so that a light beam from the first imaging optical system is incident obliquely onto the deflecting plane with respect to the main scanning direction, and at least one plane of the correcting lens being a curved-axis toric surface in which a line extending between centers of curvature of the cross section in a sub scanning direction is a curved line,wherein the optical deflector is positioned so that a reflecting point at a scanning center is shifted in a direction moving away from the center of the deflecting plane and from the light source and the following Formula 1 is satisfied: ##EQU11## wherein .DELTA.X indicates a shift amount that is the distance between the reflecting point at the scanning center and the center of the deflecting plane, .alpha. represents an angle of reflection on the deflecting plane at the scanning center, and rp denotes the radius of an inscribed circle in the optical deflector.