| 摘要 |
In a focusing servo apparatus for an optical pickup, an S-shaped wave of a focus error signal is measured at a point of time T1 to thereby calculate the time Deltat1 required for shifting the position on the S-shaped wave from a local maximum value to a local minimum value. The speed of a lens relative to an optical disk is measured on the basis of the time alphat1. When the relative speed of the lens is higher than the speed allowed to lead the focus in, the motion of the lens is braked just before (a point of time T1') the optical disk makes one rotation to thereby reduce the relative speed of the lens to make it possible to lead the focus in the optical disk steadily.
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