Optical disc apparatus, method of controlling the same, and information storage medium

Abstract

An optical disc apparatus includes an optical pickup for outputting an output signal according to reflected light from an optical disc medium, measures a level of a reflected signal corresponding to reflected light from a medium surface prior to reading of information recorded on the medium, predicts, based on the measured level of the reflected signal, whether or not the reflected signal from the medium surface will satisfy a predetermined detection condition when a focus state is to be detected, and uses a result of the predicting to detect a state where the output signal satisfies the predetermined detection condition as a state where a focus of an objective lens included in the optical pickup is on a signal surface of the medium while relatively moving the objective lens with respect to the medium surface when the information recorded on the medium is to be read therefrom.