Patent ID: 6956801
Filing Date: 2005-10-18
Classification: G11B

Abstract:
1. An optical disc drive capable of recording and playing back different kinds of optical discs, comprising a pickup for irradiating the optical disc with leaser beam, laser control means for controlling the irradiation of the leaser beam, actuator driving means for moving an objective lens which constitutes said pickup in a focus direction, focus detection photoreceiving means for detecting a focus state by means of light reflected from said optical disc, FE signal measuring means for measuring an amplitude of a focus error signal which is generated by said focus detection photoreceiving means, and optical disc discriminating means for discriminating said optical disc from the amplitude measured by said FE signal measuring means, wherein said actuator driving means brings said objective lens close to the optical disc, focus error signals are generated in front of and behind a position where the leaser beam comes into focus on a signal surface of the optical disc, said optical disc discriminating means discriminates a thickness of the optical disc from a difference in waveform of the focus error signal which is generated by focus deviation between leaser beam which passes through an outer periphery of said objective lens and leaser beam which passes through an inner periphery of said objective lens, and discriminates a kind of said optical disc from the thickness of said optical disc.