| 摘要 |
A device for accessing and locking onto a track on an information carrying medium which is optically readable and/or writable by means of a focussed beam. Said track forms on the support a series of regularly or variably spaced turns, the latter forming a spiral or being in the form of concentirc circular elements. The device comprises an optical head (1) having an optical axis A orthogonal to the plane of said support, a stationary magnetic circuit including one core (7) intersecting the set of turns of the track. A pair of coils (14, 15) moving in the head gap of said magnetic circuit is provided for accessing and radially following the track as well as for focussing the beam on the track, the optical head and the pair of coils being rigidly fixed to one another so as to form a single moving compact system. The pair of coils (14, 15) is symmetrically arranged, the desired movement being obtained by the addition of forces (F, F') induced by the currents in the coils. Application in optical disk drives.
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