OPTICAL DISK REPRODUCING DEVICE AND DISK DISCRIMINATING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a disk reproducing device which accurately detects the number of layers of a recording surface in a multilayer disk with a predetermined specification.

SOLUTION: The disk reproducing device for reproducing an optical disk medium 90 including: a plurality of recording layers with one and the same specification; and an optical system 11, counts the number of S-shaped curves of an FE (Focus Error) signal while reducing the influence of spherical aberration that changes in accordance with the position of an objective lens 11h by controlling a liquid crystal shutter 11g for moving the objective lens 11h from one side of its movable limit to the other. The number of layers of the recording surface provided in the optical disk medium 90 is detected according to the counted number of S-shaped curves of the FE signal.

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