| 摘要 |
PROBLEM TO BE SOLVED: To enable an inexpensive plastic lens be used in an image formation optical system by reducing variation in diameter of beams reflected from an optical scanning means and variation in light quantity on a image plane. SOLUTION: An optical scanner of so-called an overillumination type is disclosed which is provided with: an optical scanning means which scans by deflecting an incident luminous flux by reflection; a pre-deflection optical system which shapes the luminous flux emitted from a light source and makes incident the luminous flux into the optical scanning means; and an image formation optical system which focuses the luminous flux which is scanned with the optical scanning means on an object to be scanned. The optical scanner is characterized in that an incident angleα, projected on a main scanning plane, of the luminous flux made incident on the optical scanning means and the optical axis of the image formation optical system, andβwhich is the variation range of the scanning angle, satisfy the relation ¾α¾<β/2, and the segmentation of the optical axis before and after the deflection with the optical scanning device is performed without using a specific optical element. The image forming apparatus is applied with the optical scanner. COPYRIGHT: (C)2005,JPO&NCIPI |
