| 摘要 |
PURPOSE:To minimize a noise caused by the influence of air resistance when a polygon mirror is rotated, without decreasing optical characteristics. CONSTITUTION:The outer periphery of the mirror surface 12 of the polygon mirror 11 where the light beam from a light source is made incident is covered with a cylindrical transparent member 20, which is fixed to the rotor part 13 of the polygon motor 13 to rotate the polygon motor 13 and a rotor part 14 in one body; even when the cylindrical transparent member 20 rotates, a piping sound which is a noise is not generated since there is no corner part on the outer peripheral surface. The constitution is simplified by forming the transparent member 20 of resin in a cup shape or fixing the polygon mirror 11 to the rotor part 14 with an O ring 28 (elastic member) interposed at the center bottom part 20a of the transparent member 20, thereby improving the assembly. |
