| 摘要 |
<p>PROBLEM TO BE SOLVED: To make possible normal reproducing operation according to a disk kind by rapidly discriminating the disk kind with a curve of an S shape caused according to approach of an objective lens to a disk surface while initial focus searching. SOLUTION: In a DVD system, then S shape curve appearing at an initial focus time is different according to the disk kind. In a single layer DVD, one piece of S shape curve due to a disk reflection layer appears at a time TDS at a focus-up time succeeding to the S shape curve of a minute level due to surface reflection at a TD, and in a double layer DVD, two pieces appear. Further, in a CD, one piece appears at the time TCD. Thus, a servo signal processing part discriminates whether the loaded disk is the CD, or DVD, or the DVD, or the single layer, or double layer by the appearance of the S shape waveform by making the times TP, TDS, TCD parameters to inform a control part of the result.</p> |
