Optical disc apparatus

摘要

An optical disc apparatus comprises: rotating means for rotating an information recording medium; a light source for irradiating a light beam onto a data side of the information recording medium; converging means for converging said light beam; focus error detecting means for detecting a difference between said data side and the focus of the light beam converged by said converging means; focus direction transferring means for transferring said converging means in a direction perpendicular to said data side; focus controlling means for driving said focus direction transferring means based on the output of said focus error detecting means in such a way that said light beam converges on said data side in a predetermined state; tracking direction transferring means for transferring said light source in the radius direction of said information recording medium; and tilt calculating means for calculating average values of the outputs of said focus controlling means obtained for a period of time, which is an integer multiple of a period during which said information recording medium makes one rotation at two different points in said radius direction and calculating an inclination of said data side based on said average values at said two different points.