| 摘要 |
PURPOSE:To prevent effectively the generation of rolling by adopting the constitution that a lens drive current flows to each coil from the side close to the optical axis of the objective lens with respect to a magnetic circuit. CONSTITUTION:Focusing coils 9a, 9b and tracking coils 10a, 10b at its inside are mounted in the tracking direction at both sides of an objective lens support member 2, a couple of permanent magnets 13a, 13b, 14a, 14b are fixed to yokes 11, 12 constituting a magnetic circuit to generate a magnetic flux toward each coil. In flowing a current I to each coil, the force F in tracking direction and forces f1, f2 in the focusing direction act and the moment of the force F caused by the movement of DELTAZ of the gravity center G of the moving part is given counterclockwise and the moment of inertial of the force (f) is given clockwise, they are cancelled together. Thus, even when the objective lens is moved in the optical axis direction, rolling resonance is prevented effectively, the device is made thin and the yield is improved.
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