| 摘要 |
PROBLEM TO BE SOLVED: To prevent deterioration of performance by securing a supporting hand formed on the outer circumference of a damper having a spiral part into a groove made in the outer circumferential surface of a yoke in a magnetic circuit and supporting the magnetic circuit flexibly at two points in the center and on the outer circumferential surface thereby limiting inclination of the axis of the magnetic circuit during oscillation. SOLUTION: A damper 7 is provided with a plurality of spiral parts 30 for supporting, at the central part thereof, the center on the yoke 1 side of a magnetic circuit 20 flexibly. Three supporting hands 8 for reducing abnormal stress to the damper 7 are formed at the outer circumferential part of the damper 7. End part 22 of the supporting hand 8 is secured into the groove 21 of a yoke 1. The damper 7 is secured integrally by means of a hole 17 made in the outer fringe part and the protrusion 23 on a supporting frame 9. When a drive current is applied to a coil 5, the magnetic circuit 20 supported flexibly by the damper 7 and the supporting frame 9 oscillates but since it is supported on the outer circumferential surface of the yoke 1 by means of the damper 7, the central shaft 4 and the supporting hands 8, inclination of the axis of the magnetic circuit 20 is limited during oscillation.
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