| 摘要 |
PROBLEM TO BE SOLVED: To cut a balance groove which has an undercut on the outer peripheral surface of a rotor. SOLUTION: The rotor 5 is coupled integrally with a rotary polygon mirror 1 and faces a stator 7 to constitute a motor which rotates the rotary polygon mirror 1. The balance groove 9 is cut on the outer peripheral surface 5a of the rotor 5 and has the undercut C1, where a weight 10 as an adhesive gathers. The weight 10 never peels off with centrifugal force applied during the rotation of the rotor 5 because of the external wall 9a of the balance groove 9 formed of the undercut C1. |
