Patent ID: 6075638
Filing Date: 2000-06-13
Classification: G02B

Abstract:
An optical scanning lens comprising a single lens;said single lens comprising an optical axis, a first lens surface and a second lens surface, at least one of said first and second lens surfaces having a configuration within a plane of deflection, the configuration being asymmetrical with respect to an optical axis, the asymmetrical configuration with respect to the optical axis being designed so that a field curvature is properly corrected and a proper constant-velocity characteristic is obtained over an entire effective optical scanning area, and the plane of deflection being defined as a plane including the optical axis and parallel to a direction corresponding to a main-scanning direction,said optical scanning lens provided in an optical scanning device in which a light beam forming a line image elongated in the direction corresponding to the main-scanning direction is deflected at a constant angular velocity by a deflector having a reflecting surface in a vicinity of a position of the line image, and in which a deflected beam is focused by the optical scanning lens to form a beam spot on a surface to be scanned so as to scan the surface to be scanned,wherein a radius of curvature of at least one of said first and second lens surfaces within a plane perpendicular to the plane of deflection is denoted by a polynomial of high order .SIGMA.a.sub.n .multidot.Y**n (n=0, 1, 2, 3 . . . ) where Y denotes a distance from the optical axis in the direction corresponding to the main-scanning direction, a.sub.n denotes a coefficient of the nth order term of the polynomial, and configurations provided by the polynomial are asymmetrical with respect to the optical axis.