| 摘要 |
PROBLEM TO BE SOLVED: To improve image quality by specifying an angle formed by a straight line formed when the emitting surface of a light transmitting member abuts on the extended surface of the light beam scanning surface of a scanning lens with the optical axis of the scanning lens. SOLUTION: In a horizontal cross section showing the setting angle of the light transmitting member 291 of a light deflecting unit 100; incident light on a rotary polygon mirror 22 is L1 and the center line (scanning optical axis) in the main scanning direction of emitted light from the mirror 22 rotating is L2. In the unit 100, the member 291 is arranged to be inclined so that the tilt angleθformed by the plane Y of the member 291 with the scanning optical axis L2 may be 63 to 83 deg.. A space part Z2 near an aperture part 101A on the inner surface side of the member 291 is made minimum and almost uniform to other space parts. By setting the tilt angleθof the member 291 within the range of 63 to 83 deg., a drift part due to the high speed rotation of the mirror 22 hardly exists in the space part Z2, so that wind whistle is restrained and the high speed rotation is realized. |
