| 摘要 |
PURPOSE:To eliminate an influence of the surface wave of a polygonal mirror upon the quality of printing by forming the reflection face of the polygonal mirror in the thickness direction with the same curvature as an arc described with the mirror center as the center. CONSTITUTION:The side face of each of 6 side parts of a polygonal mirror 6 functions as a reflection face 6a, and the shape in the thickness direction (cross section) of the reflection face 6a is formed to a convex face consisting of an arc face formed with the same curvature as an arc described with the mirror center as the center. Consequently, laser light is reflected in the same state which ever position of reflection faces 6a is made incident on. Thus, all of the laser light made incident on the polygonal mirror 6 passes the same optical path after being reflected by the reflection face 6a of the polygonal mirror 6 though the reflection face 6a is displaced in the thickness direction of the mirror by surface wave of the polygonal mirror 6, and the optical path is not deflected, and the image of the laser light is formed at a prescribed image forming point on the surface of a photosensitive body without positional deviation. |
