| 摘要 |
PROBLEM TO BE SOLVED: To stably discriminate the kind of a disk without being influenced by variations among apparatuses. SOLUTION: Reflection levels on the surface and recording layer of a disk are respectively detected by using a red laser and a blue laser and the ratios Rr, Rb of reflection levels on the surface and recording layer of the disk are calculated. On the basis of the reflection level ratios Rr, Rb, the sort of the disk, i.e. whether the disk is a DVD using the red laser or an HD-DVD using the blue laser is discriminated. COPYRIGHT: (C)2007,JPO&INPIT
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