| 摘要 |
PURPOSE:To change the print size without correcting a program by arranging a convex lens on the optical axis of the laser light between a photosensitive body and a polygonal mirror and controlling forward and backward movement of this convex lens along the optical axis to control the scanning width on the photosensitive body and changing the angle of the convex lens to the optical axis in each scanning. CONSTITUTION:A laser light 5 emitted from a semiconductor laser device 4 is reflected on the mirror surface of a polygonal mirror 3 and passes a convex lens 2 and exposes a photosensitive drum 1 to form a latent image in the scanning direction of an arrow 6. When the print size will be reduced, the convex lens 2 is displaced to the side of the photosensitive drum 1 by a position control mechanism 8. The exposure range is narrowed in accordance with the extent of change of the position of the convex lens 2 to reduce the scanning width. After the start of scanning, scanning is performed while the convex lens 2 is changed from the attitude leaning to the front toward the attitude leaning to the rear at a certain proportion for each scanning by an angle control mechanism 9 to control an angle theta. Thus, a higher-order program is not corrected to change the print size. |
