DISK IDENTIFYING METHOD

摘要

Data recorded on a CD-R disk is prevented from being damaged by a short-wavelength laser beam when reproduced by means of an optical disk device for reproducing data recorded on an optical disk of one of types which are different from each other in packing density by using one of laser beams which are different from each other in wavelength. While the disk is at rest, a laser beam with a long wavelength is projected onto the disk to check if the disk is a CD-R disk. If not, another laser beam with a short wavelength is projected to check if the disk is a DVD disk. The disk is identified according to a focus error signal generated when a focusing lens (10) is moved by an actuator (9) along the projection axis or according to a total light intensity signal (AS).