| 摘要 |
PURPOSE:To satisfy all of an f-theta correction, correction of face inclination of a scanning mirror, linearity of scanning and focusing by forming an incident/reflection face of scanning light to the concave curved shape which is specific respectively in a main scanning direction and sub-scanning direction and forming a grating for correcting the focus in the sub-scanning direction. CONSTITUTION:The incident/reflection face 110 for scanning light is formed to the concave curved shape of an approximately quadratic curve in the main scanning direction X and in the sub-scanning direction Z, said face is formed to the concave curved shape the curvature of which increases gradually from the central part in the main scanning direction toward both side parts; furthermore, the grating 120 for correcting the focus constituted by varying spacings gradually in the sub-scanning direction Z is formed to the incident/reflection face. The f-theta correction of the scanning light scanned by the scanning light is, therefore, assured by the concave curved shape in the main scanning direction of the face 110 and the face inclination of the scanning mirror and linearity of the light scanning line on the surface of a photosensitive drum is assured by the concave curved shape in the sub-scanning direction; in addition, the focus on the surface of the photosensitive drum is corrected by the grating 120 of the face 110 over the entire part of the light scanning line. |
