Patent ID: 6288987
Filing Date: 2001-09-11
Classification: G11B

Abstract:
An optical disc device comprising:a laser light source for radiating a laser light beam illuminated via an objective lens on a signal surface of an optical disc;return light detection means for detecting the reflected light radiated from the laser light source and reflected from the signal surface of said optical disc;disc discriminating means for discriminating the type of said optical disc based on a detection output of said return light detection means;means for detecting tracking error signals of plural different types of different detection systems based on the detection output of said return light detection means;tracking means for displacing the objective lens along the radius of said optical disc responsive to said tracking error signals for tracking-controlling a laser spot of the laser light focussed on the signal surface of the optical disc; andcontrolling means for controlling operation of said optical disc device based on discriminating output, wherein said disc discriminating means finds the reflectivity from the signal surface of the optical disc from the signal level of the detection signal corresponding to the light intensity of the reflected light detected by said return light detection means during an operation for focussing said objective lens onto said signal surface for discriminating the types of the optical discs based on the reflectivity from the signal surface of the optical disc and known reflectivities of different materials that signal surfaces of the plural types of optical discs comprise.