Image scanning and recording method and apparatus for compensating for a pyramidal error of a rotating polygon

摘要

An image scanning and recording method for compensating for a pyramidal error of a mirror surface of a rotating body having at least two reflective mirror surfaces by fine-adjusting an angle of a light beam incident on the rotating body. A scanning lens is put in such a manner that an optical axis of the scanning lens is orthogonal to a rotating axis of the rotating body. An angle made of the incident light beam and a main scanning plate is controlled so that equations (I) and (II) are selectively fulfilled, the main scanning plane being orthogonal to the rotating axis and including the optical axis: tan alpha =tan2 delta xcos(a-b) (I) alpha =2 delta xcos(a-b) (II) where a: a rotating angle of a normal line standing on each mirror surface with respect to the optical axis of the scanning lens, b: an angle made of the incident beam and the optical axis of the scanning lens on the main scanning plane, and delta : the pyramidal error of each mirror surface with respect to the rotating axis.