OPTICAL DISC DEVICE AND OPTICAL DISC DISCRIMINATING METHOD

摘要

PROBLEM TO BE SOLVED: To provide an optical disc discriminating method capable of discriminating the type of a disc due to a difference in substrate thickness with high accuracy. SOLUTION: An objective lens is shifted, while irradiating a disc with laser beams, the maximum value FEmax and the minimum value FEmin of a focus error signal and the maximum value FSmax of the amplitude of a focus sum signal are measured, and the type of the disc is discriminated by comparing the value "(FEmax-FEmin)/FSmax" with a discriminating value. COPYRIGHT: (C)2008,JPO&INPIT