| 摘要 |
PROBLEM TO BE SOLVED: To improve durability of a bearing supporting rotation of a rotary polygon mirror. SOLUTION: A rotary polygon mirror 1 is integrally coupled with a flange member 4 of an elastic pressurizing mechanism 8 having a presser spring, etc., and rotated by a motor comprising a rotor magnet 5 and stator coils 7. The flange member 4 is fixedly mounted on a rotary shaft 3 by engaging a downward shaft part 4b with an inner diameter part 3a of the rotary shaft 3 by shrinkage fitting or bonding. Since almost the whole circumferential length of an outer peripheral surface of the rotary shaft 3 is fitted with a sleeve 2 for the use of a dynamic pressure bearing, a center position G1 of the bearing and a center of gravity G2 of the entire rotor body including the rotary polygon mirror come near to each other, and this arrangement can reduce friction, etc., caused by whirling. |
