| 摘要 |
PROBLEM TO BE SOLVED: To provide an objective lens drive device reduced in loss in magnetic flux due to a return-path part and a magnetic cover and improved in the uniformity of a magnetic flux density distribution. SOLUTION: In this objective lens drive device, the return-path part 81R of a magnetic yoke 81A and the magnetic cover 81B constituting a magnetic circuit making the magnetic flux act on a focusing coil and a tracking coil have a detour structure in the direction orthogonally intersecting the direction of magnetic poles of driving permanent magnets 2a, 2b in a plane orthogonally intersecting an objective lens optical axis, and a magnetic flux flow spring out from the driving permanent magnets 2a, 2b to an air gap G where the focusing coil and the tracking coil are placed is made to arrive at an opposite surface side without passing through the return-path part 81R and the magnetic cover 81B, and the magnetic flux density in the vicinity of the peripheral edge parts of the driving permanent magnets 2a, 2b is increased, and the uniformity of the magnetic flux density distribution of the air gap is enhanced.
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