| 摘要 |
PURPOSE: To prevent the reflection angle of a returning mirror from being changed when a cover is assembled with an optical box. CONSTITUTION: Scanning light L1 deflectively scanned by a rotary polygon mirror 3 is imaged on a rotary drum 6 through an image forming lens 4 and the returning mirror 5. The upper opening of the optical box 7 for housing the rotary polygon mirror 3 and the returning mirror 5 is closed by the cover 9. The side wall 7a of the optical box 7 is provided with a step part 7d near the returning mirror 5, and the step part 7d prevents the mirror 5 from coming into contact with the cover 9, and the cover 9 is made to abut on the remaining part, then, the cover 9 is fixed by a screw. |
