| 摘要 |
PURPOSE:To improve the sensitivity of the drive by providing a prevention means to prevent the leak of magnetic flux from the open part of magnetic circuit. CONSTITUTION:The titled driver is covered with a cover 10 to protect moving parts from an external impact, and on the inner surface of the cover 10, iron pieces 11 excellent in permeability are bonded in locations where magnetic flux is apt to leak in a manner that they 11 are located on a magnet 6a, a yoke 5c, a magnet 6b, and a yoke 5c contacting them respectively, so that the magnetic flux leaking from a magnetic gap passes through the iron peices 11 when the objective lens driver is covered with the cover 10. With such a constitution, only by covering the titled driver with the cover 10, the magnetic circuit is held in a closed-status, and the leakage of magnetic flux from the magnetic gap can be decreased.
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