Patent ID: 6026065
Filing Date: 2000-02-15
Classification: G11B

Abstract:
An optical disc data pick-up apparatus for reading data from an optical disc, comprising:a light source constructed and arranged to emit a beam of light;an objective lens for condensing said beam onto the optical disc;numerical aperture control means for controlling an effective numerical aperture value of said objective lens by controlling a size of said beam reaching said objective lens, so as to execute a focusing operation with respect to the optical disc;a photo-detector constructed and arranged to receive light corresponding to said beam reflected by the optical disc, and to generate a first signal in response to said reflected light;a beam splitter constructed and arranged to transmit said beam from said light source towards said objective lens, and to reflect said reflected light towards said photo-detector; anda tracking control unit;a focus control unit;reproducing signal processing means for generating and transmitting a second signal to said tracking control unit and said focus control unit corresponding to said first signal outputted from said photo-detector;disc identifying means for identifying an optical disc having a particular thickness and generating a corresponding third signal, based on said second signal from said reproducing signal processing means;a numerical aperture control means driving apparatus for driving said numerical aperture control means according to a thickness of the optical disc identified by said disc identifying means;a spindle motor;a motor control unit for controlling said spindle motor in accordance with the identified optical disc;a digital signal processing unit connected to said reproducing signal processing means and to said motor control unit; anda microcomputer constructed and arranged to selectively control at least one of said numerical aperture control means driving apparatus, said focus control unit, said tracking control unit, and said motor control unit in accordance with said third signal from said disc identifying means.