| 摘要 |
PROBLEM TO BE SOLVED: To precisely reproduce or record information from an optical disk. SOLUTION: In consideration that reflectance of a laser beam on a surface of the optical disk 70 is approximately constant irrespective of the type of the optical disk 70, the amount of light of the reflected laser beam in which the laser beam is reflected on the surface of an arbitrary optical disk 70 is measured as a temporal signal level V1, which is compared with a reference signal level V0 measured when shipped from a factory so that a degree of decrease in the amount of light reaching the surface of the optical disk 70 is recognized. A signal level decreased due to temporal factors is corrected to the level equivalent to that when shipped from the factory by adjusting the gain of RF servo according to the degree of decrease, the reflectance of a recording layer of the optical disk 70 can be precisely recognized, and the type of the optical disk 70 can be precisely discriminated at high accuracy. COPYRIGHT: (C)2008,JPO&INPIT
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