METHOD FOR DETECTING FOCUS DISLOCATION ERROR SIGNAL OF OPTICAL HEAD AND OPTICAL WRITING PLAYBACK APPARATUS USING THE SAME

摘要

The invention relates to a method of detecting a focus error signal of an optical head to be used for controlling the focus position of an objective lens for converging a light beam on an optical recording medium and an optical recording/reproducing apparatus. The invention provides a method of detecting a focus error signal of an optical head which allows a focus error signal to be detected a track cross signal therein attenuated at a plural types of optical recording medium having different physical track pitches and an optical recording/reproducing apparatus employing the method. A light beam emitted by a laser diode is diffracted by a diffraction grating to split it into a main beam and two sub beams of orders of ±1. The main beam and the two sub beams of orders of ±1 are received by three light-receiving elements after being reflected by an optical recording medium, and a focus error signal in which a track cross signal has been attenuated is detected by an error signal detection unit based on electrical signals obtained by photoelectric conversion.