| 摘要 |
PURPOSE:To prevent a mirror surface from being stained by covering mirror surfaces of the polygon mirror except a gap for optical path formation when the rotary polygon mirror is incorporated in part of a motor. CONSTITUTION:A cover 18 which has an end part for covering mirror surfaces 10A of the rotary polygon mirror 10 is provided integrally on the top and reverse surfaces of the rotor which has the rotary polygon mirror 10 and a magnet. The cover 18 is made of magnetically permeable material such as aluminum and its radial end part 18a is extended outward beyond the mirror surfaces of the rotary polygon mirror 10 and bent to cover the mirror surfaces. Then, the bending height of the radial end part 18a of the cover 18 is so set that the gap G for the optical path D to the mirror surfaces 10A is formed when the covers 18 are joined with the top and reverse surface of the rotor. |
