| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk device in which stable reproduction can be achieved by detecting stain such as dust and finger prints or the like on a disk and inputting respectively corresponding control signals to a PLL circuit. SOLUTION: A total signal, which is a total reflection amount from an optical disk, is converted into control signals having equal to or greater than three values in accordance with the strength of the total signal. Then, when reduction in the RF signal level is large by the existence of dust or the like, conventional operation hold is conducted for the PLL circuit. When reduction in the RF signal level is small for the case of stain such as finger prints or the like, the gain of the PLL circuit is switched to prevent occurrence of a hypersensitive response of the PLL circuit within the range. COPYRIGHT: (C)2006,JPO&NCIPI
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