| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical scanner suitable for compact and high definitive printing by properly setting a lens shape of one sheet of an fθlens. SOLUTION: The light outgoing from a light source member 1 is converted into the converged light by a first optical element 2, and the converted light is image formed on a deflection surface of a deflection element 5 in a linear shape longitudinal in the main scan direction through a second optical element 4, and the light deflected by the deflection element 5 is image-formed on a surface to be scanned in a spot shape through a third optical element (fθlens) 6. Then, when the surface 7 to be scanned is scanned, the third optical element 6 consists of a single lens, and the single lens forms a meniscus shape projective to the deflection element 5 side in the main scan surface, and the first lens surface of the deflection element 5 side and the second lens surface of the surface 7 to be scanned are formed in an aspherical shape also, and the aspherical shape of the second lens surface forms the shape crossing in the peripheral part for the tangent of the radius of paraxial curvature and approaching to the deflection element 5 side in the outermost part. |
