| 摘要 |
PROBLEM TO BE SOLVED: To prevent chatter vibration, etc., of a member which seals the part between an optical box and a lid member. SOLUTION: A rotary polygon mirror R1 and an image forming lens system F1 which images its scanning light on a photosensitive body are put in an optical box 10, and the opening of the optical box 10 is closed with the lid member 20. The optical box 10 has an inverted L-shaped elastic member 14 which is arranged along its peripheral wall 12 and an L-shaped peripheral wall rib 22 provided at the peripheral edge of the lid member 20 is locked to the elastic member 14 to fix the lid member 20 to the optical box 10. In this state, the elastic member 14 is elastically pressed against the peripheral wall rib 22 to seal the part between the lid member 20 and optical box 10. |
