Patent ID: 7715287
Filing Date: 2010-05-11
Classification: G11B

Abstract:
1. An optical disc apparatus comprising: a laser diode; a first optical component which branches beams from the laser diode into a first beam and a second beam; an objective lens which focuses the first beam on a recording film surface of an optical information recording medium, and which detects the reflected beam; a reference mirror provided in an optical path of the second beam; a first photo detector; a second photo detector; a second optical component which branches beams obtained by combining the first beam reflected by the optical information recording medium and the second beam reflected by the reference mirror, and which makes the branched beams incident on the first and second photo detectors respectively; an optical head which holds the laser diode, the first optical component, the objective lens, the reference mirror, the first photo detector, the second photo detector and the second optical component; an actuator which drives the optical head in an optical axis direction of the objective lens; and a signal processing part which generates a read-out radio frequency signal and a focus error signal from an output signal of the first photo detector and an output signal of the second photo detector, wherein the signal processing part generates the read-out radio frequency signal from a differential signal between the output signal of the first photo detector and the output signal of the second photo detector, and the actuator is subjected to feedback control by use of the focus error signal.