DISK THICKNESS DISCRIMINATING DEVICE OF OPTICAL RECORDING MEDIUM

摘要

PURPOSE: To facilitate the identification of optical disks having different thicknesses by the simple structure of a device. CONSTITUTION: A disk thickness discriminating part 50 decides whether a substrate thickness signal Dt is larger than a prescribed threshold value or smaller than the prescribed threshold value with the timing of the peak value of a reproducing signal IS. Thereby, the disk thickness discriminating part 50 detects the level of the substrate thickness signal Dt with the timing of a peak value of the reproducing signal IS for focus drawing in an initial condition in which an objective lens 1 is forcedly oscillated and decides the thicknesses of two kinds of disk substrates 2 based on the level.