| 摘要 |
PROBLEM TO BE SOLVED: To shorten a start-up time of an optical disk and to stably pull a focus by pulling the focus while rotationally driving the optical disk, in a focus servo device for an optical pickup. SOLUTION: An S shaped waveform of a focus error signal is measured at the time T1, the timeΔt1 until the S shaped waveform transfers from the relative maximum to the relative minimum is obtained, a relative speed between a lens and the optical disk is measured based on theΔt1. When the relative speed is faster than a focus pull-in speed, a movement of the lens is braked right before the optical disk finishes one rotation (time T1') and the relative speed is decreased. Thus, the stable pull of a focus is enabled.
|
