| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk drive device, a number of recording layer discrimination method for an optical disk and a recording medium recording the number of recording layer discrimination program for the optical disk eliminating erroneous discrimination of the number of recording layers in the optical disk, evading erroneous operation in adjustment at every recording layer and in a jump between recording layers thereafter and warranting stable operation. SOLUTION: Information is recorded or reproduced on plural recording layers of the optical disk. A microcomputer rocks a focus actuator, and discriminates the number of recording layers of the optical disk by a focus error signal obtained from a reflection beam of a beam irradiating the optical disk according to a relation between the S-shaped curve of the focus error signal and a time (S9), or according to the relation between the S-shaped curve of the focus error signal and a focus actuator drive voltage.
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