| 摘要 |
<p>In advance of the playback of an optical disk 11, the peaks of a focus error signal are detected, and the reference values of the focus error signal are set on the basis of the values of the peaks. In executing a layer jump, a kick signal for an object lens 13a is stopped from being outputted when the focus error signal exceeds the reference value of one polarity. A brake signal is outputted when the focus error signal exceeds the reference value in the opposite polarity. A time period for which the brake signal is outputted, is set on the basis of a time period for which the kick signal has been outputted. After the stop of the output of the brake signal, the peak of the focus error signal is waited for, whereupon a focusing servo 21 is turned ON. Thus, a layer jump technique of high stability is provided which copes with discrepancy in the error levels of individual disks or playback apparatuses, and changes in the characteristics of the playback apparatus attributed to ambient conditions such as temperature.</p> |
