| 摘要 |
In an apparatus having an objective lens for projecting a light spot on a track of a disc-shaped record medium, the objective lens is driven in a tracking direction perpendicular to an optical axis of the objective lens and to a track tangential direction in accordance with a tracking error signal representing a deviation of the light spot from the track by means of a tracking control mechanism including first and second permanent magnets, first and second magnetic members connecting the same poles of the permanent magnets, a third magnetic member holding the objective lens and arranged movably in the tracking direction within a space surrounded by the first and second permanent magnets and first and second magnetic members, and first and second coils wound around the first and second magnetic members at middle portions thereof. A resonant vibration is dumped by providing a motional feedback loop in which a displacement of the third magnetic member is detected by a pair of magnetoelectro transducing elements secured to the first and second permanent magnets, respectively at middle portions thereof so as to detect change of magnetic fluxes leaked out of the third magnet member in opposite directions along the tracking direction. |
