Patent ID: 8054716
Filing Date: 2011-11-08
Classification: G11B

Abstract:
1. An optical disc apparatus comprising: a spindle motor that rotates an optical disc; an optical head that irradiates the optical disc with laser light to read information therefrom or write information thereto, the optical head including an actuator that changes a focus position of the laser light; a front end that includes a back end of encoder and decoder that processes video, audio, and other signals; a main controller that controls the front end and the back end; and a memory that stores various kinds of data, wherein in a first process performed during a manufacture of the optical disc apparatus, the memory stores a range of voltages as defocus values appropriate for smooth operation of the optical disc apparatus, the range of defocus values being determined according to defocus values measured respectively, with respect to the optical disc apparatus, when an amplitude of an RF signal is maximal, when an amplitude of a tracking error signal is maximal, when a jitter value is optimal, and when an error rate is optimal, and in a second process performed during a driving of the optical disc apparatus, the main controller, when data is read from a previously recorded optical disc, measures a defocus adjustment value obtained when an amplitude of an RF signal of an optical disc loaded in the optical disc apparatus is maximal, when data is written to an optical disc, measures a defocus adjustment value obtained when an amplitude of a tracking error signal of an optical disc loaded in the optical disc apparatus is maximal, when the defocus adjustment value thus measured is within the range of defocus values, uses the measured defocus adjustment value as a focusing bias value, and otherwise uses as a focusing bias value a value obtained by correcting the measured defocus adjustment value so as to bring the defocus adjustment value within the range of defocus values.