| 摘要 |
PROBLEM TO BE SOLVED: To improve an image quality by suppressing the vibration of the extended part of a frame. SOLUTION: The frame 11 is provided with a first part 11A fixed on the image forming device and a second part 11B extended like a cantilever in the air as a united form. The frame 11 has a surrounding wall 21 which encloses optical parts, directed toward the approximately normal direction with respect to a scanning plane, and four fixing parts 23, each of which has a fixing hole 22, with an interval in a way that the fixing parts surround the first part 11A on the outer side of the surrounding wall 21. Notches 25 for suppressing a resonance of the second part 11B are formed on the sides of beginning and terminating of writing in the direction of the scanning of a laser beam, respectively, on the surrounding wall 21 of the frame 11 between the first part 11A and the second part 11B. The notches 25 vary the propagating condition of the vibration between a deflection scanning unit 14 and the second part 11B and suppress the possibility that the resonance frequency of the second part 11B approaches the rated speed of revolution of the deflection scanning unit 14. |
