Patent ID: 6147941
Filing Date: 2000-11-14
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;a detection system including a detector for detecting the reflected light radiated from the laser light source and reflected from the signal surface of said optical disc;a discriminating circuit for discriminating the type of said optical disc based on a detection output of said detector;a tracking circuit for detecting tracking error signals of plural different types of different detection systems based on the detection output of said detector;a tracking servo 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; anda controller for switching said tracking circuit based on a discriminating output by said discriminator circuit for selecting one of plural types of tracking error signals responsive to the types of the optical discs, wherein said detector includes first, second and third error signal generating circuits for performing pre-set calculations on plural detection signals selected from detection signals A, B, C, D, E, F, G and H from the detector for generating first, second and third tracking error signals and a selection circuit for selecting one of said first, second and third tracking error signals.