| 摘要 |
PURPOSE:To prevent the generation of auxiliary resonance of a driving system which has influence upon a servo band by supporting an optical system with a revolving shaft in the position of the center of gravity and arranging two actuators in positions symmetrical with respect to the revolving shaft. CONSTITUTION:The whole of the optical system is supported by the revolving shaft provided at the intersection of a cross spring 11 which is the position of the center of gravity, and a pole brace 15 is connected to a movable part 5, and a pole brace 16 is connected to a housing 12. Two actuators 2 consisting of coils 2a and magnetic circuit 2b are arranged in positions symmetrical with respect to said intersection. Consequently, parallel forces except a couple of forces of the actuator are cancelled in the movable part to reduce a coefficient of excitation, and the force of inertia due to unbalance of rotation is not applied to the bearing because the rotation center is the position of the center of gravity of the movable part, and thus, the exciting force of auxiliary resonance, which has influence upon the servo band, due to the bearing is reduced to suppress auxiliary resonance. |
