| 摘要 |
PURPOSE:To obtain an objective lens driving device where a restoring force and a vertical drag to a sliding surface do not occur and which is easy to be controlled by setting a magnetic circuit consisting of a permanent magnet and a yoke only in a movable part and setting only parts consisting of nonmagnetic material such as a coil for control, etc., in a fixed part. CONSTITUTION:The first coil 10 for controlling difocusing and the second coil 11 for controlling off-track are provided in the fixed part 15 and the yoke 14 and a permanent magnet 5 are provided in a movable holder 2 which is the movable part, then the permanent magnet magnetically fixed to at least one of the first coil and the second coil in order to interlink fluxes whose directions of adjacent vectors are nearly reverse. Thus, since the parts consisting of the magnetic material are not set on the fixed side near to the movable holder, the distribution of flux density of the permanent magnet surface does not alter even if the device actuates and the force of a focus control direction (restoring force) does not occur in the permanent magnet. Since the parts consisting of the magnetic material do not exist on the fixed side the vertical drag (the force in a radial direction, occurring in the permanent magnet) does not occur even if the permanent magnet has the asymmetry of the distribution of flux density.
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