Patent ID: 7564748
Filing Date: 2009-07-21
Classification: G11B

Abstract:
1. An optical disk recording/reproducing apparatus comprising: an optical pickup that has an objective lens for converging laser beams to a track on an optical disk; a tracking servo system for tracking-controlling the objective lens according to a tracking error signal generated from an RF signal sent from the optical pickup; and a focusing servo system for focusing-controlling the objective lens according to a focusing error signal generated from an RF signal sent from the optical pickup, wherein: the tracking servo system includes: in a case where a laser beam converged by the objective lens shifts from a central position of a track of the optical disk, the tracking servo system performs a control operation of increasing a gain of the tracking servo amplification circuit to thereby correct a controlling force acting upon a tracking servo actuator; the focusing servo system includes: a focusing servo filter for appropriately adjusting a frequency characteristic of a focusing error signal generated from an RF signal sent from the optical pickup; a focusing servo lowpass filter for extracting a low-frequency component of the focusing error signal sent from the focusing servo filter; a focusing servo amplification circuit for amplifying the focusing error signal directly sent from the focusing servo filter and for adjusting a gain thereof according to a low-frequency component signal directly sent from the focusing servo lowpass filter; and a focusing servo drive circuit for outputting a drive signal that is used for performing focusing-position-control of the objective lens according to a signal sent from the focusing servo amplification circuit; and in a case where a laser beam converged by the objective lens shifts from a focal position on a track of the optical disk, the focusing servo system performs a control operation of increasing a gain of the focusing servo amplification circuit to thereby correct a controlling force acting upon a focusing servo actuator.