| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk device with improved accuracy in discrimination even among optical disk mediums being close to each other in thickness between surface and recording layer. SOLUTION: The optical disk device, which reads a signal recorded on an optical disk medium, moves an objective lens relatively with respect to the surface of an optical disk medium, and simultaneously detects surface reflection on the surface of the optical disk medium, an alias signal occurring based on the surface reflection and reflected light from the data recording layer of the optical disk medium to discriminate the kind of the optical disk medium based on the ratio of a first period from the time of detecting the surface reflection to the time of detecting the alias signal and a second period from the time of detecting the surface reflection to the time of detecting the reflected light from the data recording layer. COPYRIGHT: (C)2008,JPO&INPIT
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