| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to switch two kinds of objective lenses by using a drive system performing tracking and focusing. SOLUTION: Two kinds of objective lenses 4, 5 are attached to a lens holder 3, and on the other hand, respective magnets 6 are magnetized along the nearly radial direction of the lens holder 3, and respective magnetic bodies 9 are provided on plural positions in the circumferential direction of the lens holder 3, and magnetic neutral positions are set. In respective magnetic neutral positions, one side between respective objective lenses 4, 5 is placed on an optical path O performing pickup, and the end parts facing each other of the adjacent tracking coils 7 are arranged respectively oppositely in the vicinity of both end parts of respective magnets 6. Rotational force is imparted to the lens holder 3 by generating magnetic force at the end parts facing each other of respective tracking coils 7 from such a state, and the magnetic neutral positions are moved, and the objective lenses 4, 5 placed on the optical path O are switched, and on the other hand, a focusing coil 8 is formed by being wound around along the outer circumference of the lens holder 3. |
