Patent ID: 6532095
Filing Date: 2003-03-11
Classification: G02B

Abstract:
An optical scanner, comprising:a collimator lens for collimating a light beam emitted from a laser light source; a rotating polygon mirror for deflecting and reflecting said light beam; a cylindrical lens disposed so that said light beam from said collimator lens is formed near a reflection surface of said rotating polygon mirror as a line image; and an image-forming optics system for converging said light beam, deflected and reflected by said rotating polygon mirror after having passed through said cylindrical lens, at a predetermined scan surface, and for scanning said converged light beam on said surface at uniform velocity; said light beam being obliquely incident on said reflection surface with respect to both a first plane perpendicular to an axis of rotation of said rotating polygon mirror and a second plane, perpendicular to said first plane, which includes the central axis of said image-forming optics system; wherein said cylindrical lens is disposed so that its generating line is substantially parallel with said first plane, and wherein, when it is assumed that a plane, including both said central axis and an x-axis perpendicular to both said central axis and said axis of rotation, before the rotating polygon mirror is inclined, is an x-z plane and that a plane, including both a y-axis perpendicular to said x-z plane and said central axis, is a y-z plane, an angle &agr;, which is formed within said x-z plane by both said light beam incident on said reflection surface and said central axis, an angle &bgr;, which is formed by said y-z plane and said light beam incident on said reflection surface, an angle &ggr;, which is formed by the generating line of said cylindrical lens and said x-z plane, an angle &phgr;, which is formed by both said axis of rotation projected on said x-y plane and said central axis, and an angle &dgr;, which is formed by said y-axis and said axis of rotation, satisfy the following equation: &ggr;=tanâˆ’1{(cos &agr; sin &phgr; sin &dgr;âˆ’sin &agr; cos &phgr; sin &dgr;)/(sin &agr;sin &bgr; sin &phgr; sin &dgr;+cos &bgr; cos &dgr;+cos &agr; sin &bgr; cos &phgr; sin &dgr;)}.