| 摘要 |
PROBLEM TO BE SOLVED: To provide an actuator for an optical pickup in which the phase change of an objective lens is minimized. SOLUTION: The phase change of the objective lens is minimized by adjusting the quantity of leakage flux. The actuator has a moving part of an asymmetrical form centering on the lens, and the driving force of the moving part is generated from a magnetic circuit consisting of a permanent magnet, a yoke, and a coil. The actuator is equipped with a sub focusing coil located around the magnetic circuit, and a magnetic flux control member for controlling a leakage flux generated from the magnetic circuit and intersecting the sub focusing coil. By changing the moment of force which occurs in the external coil side of an effective magnetic space, and which affects a moving part, the phase change of the objective lens can be minimized in a rotational oscillation mode, especially in a pitching mode.
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