| 摘要 |
PURPOSE:To prevent data on a disk from being erased erroneously by leakage flux, by setting the driving forces generated in a pair of focus coils and a pair of tracking coils at the same driving directions, and setting the polarities of a pair of magnets different from those of a pair of counter yokes facing with the pair of magnets. CONSTITUTION:A pair of focus coils 36a and 36b are connected so that their driving forces generated by an electromagnetic function working with a pair of magnetic circuits are set in te same directions of focusing when permitting a current to flow. Next, a pair of tracking coils 34a and 34b are connected so that their driving forces generated by the electromagnetic function working with the pair of magnetic circuits are set in the same directions of tracking when permitting the current to flow. And the polarities of the magnets 52a and 52b facing with counter yokes 56a and 56b are set in different one. In this way, the leakage flux flows in arrow head direction without repulsing under an objective lens 44. Thereby, the leakage flux flows without giving an undesirable effect on the recording plane of a disk 50 on the lens 44, and the data on an optical magnetic disk is prevented from being erased or recorded erroneously.
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