| 摘要 |
PROBLEM TO BE SOLVED: To accurately device the kind (CD/DVD, single-layered/multi-layered) of a disk. SOLUTION: An objective of an optical pickup is ascended at a fixed speed toward a disk near position from a disk far position and a peak/bottom detector detects levels (peak-to-bottom level) from the peak to the bottom of a focus error signal obtained by the focus movement. A servo processing microcomputer counts the number of focus error signals having a peak-to-bottom level not smaller than the predetermined minimum level out of the peak-to-bottom levels obtained during the focus movement across the recording layer of the disk and decides the kind of the disk 1 according to the count value. Consequently, the kind of the disk can accurately be decided without being affected by characteristic differences of devices, variation in the reflectivity of the disk, variation in the ambient temperature, and fake pulse caused by waviness of reproduction output. COPYRIGHT: (C)2003,JPO
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