| 摘要 |
PURPOSE:To keep directivity of the direction of optical axis of an optical system constant invariable by making movement of the optical system in the direction of focus by a supporting means formed of a support having a planetary gear. CONSTITUTION:At the time of moving an objective 38 in the direction X, tracking direction, the objective 38 is moved by making a holder 42 slide on a shaft 45 by mutual action of a magnetic field formed by a permanent magnet 62 and a magnetic field generated by applying current to a coil for tracking. On the other hand, at the time of moving the objective 38 in the direction Y, focus direction, the objective 38 is moved by mutual action of a magnetic field formed by a permanent magnet 34 and a magnetic field generated by applying current to a focus coil 36 keeping the lens constant to the direction of optical axis. The movement is made using a supporting means that utilizes planetary gears consisting of a gear 50 fixed to a fixing plate 46, a gear 58 that meshes with the gear 50 and a gear 60 that meshes with the gear 58.
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