| 摘要 |
PURPOSE:To attain accurate focus control with excellent frequency characteristic not by sliding an optical system in focal direction but by turning by means of a parallel link mechanism. CONSTITUTION:In case an objective lens 38 is moved in the focal direction, since a holder 42 of an optical system driver 30 is connected to arm support members 52, 54 by two arms 48, 50, so-called parallel link mechanism, the objective lens 38 of an objective lens holder 40 fixed to a holder 42 is moved while keeping the parallel state with a base 32 at all times. Thus, no deflection of an optical axis of the objective lens 38 is caused and the objective lens is moved. Further, the objective lens 38 is moved in the tracking direction by allowing the holder 42 to slide the arms 48, 50 through the mutual operation between the magnetic field generated by casing a current to flow to a tracking coil and the magnetic field by a permanent magnet 56.
|
