| 摘要 |
PURPOSE: An objective lens drive unit of an optical pickup is provided to prevent interference between vertical and horizontal movements of a bobbin as well as rolling by improving the structure. CONSTITUTION: A bobbin(10) is set on a base(100), and four take-up portions(10a-10d) are attached to the bobbin with focusing/tracking coils(21,22,31,32). Focusing/tracking magnets(41,42,61,62) and focusing/tracking yokes(51,52,71,72) are mounted in accordance with the focusing/tracking coils. A magnetic field is formed perpendicular to an electric current flowing through each coil by the magnets and yokes. Thereby, an electromagnetic force is formed according to Fleming's left-hand law to drive the bobbin in an X or Y direction. A magnetic fluid is injected between each magnet and coil and between each coil and yoke. The magnetic fluid is a liquid magnetized by a magnetic field and is arranged in the magnetic field depending on magnetic flux distribution. The bobbin is floated from the base(100) by the magnetic fluid. Therefore, rolling and interference between vertical and horizontal movement are inhibited.
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