| 摘要 |
PURPOSE:To attain the focus position control with a wide servo band by reinforcing a square drive coil by means of a fixing frame for an objective lens and increasing the high band resonance frequency of a matter to be driven. CONSTITUTION:The flanges 18a-18d of a lens frame 11a are welded on the upper surface of a focusing coil 12 for reinforcement of four sides of the coil 12. Then a lens frame 11b is welded to two sides of the lower surface of the coil 12 for reinforcement. Such a lens frame fixed to an objective lens at the center part increases the rigidity of a vibration system including the objective lens and a drive coil.
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