Patent ID: 6292446
Filing Date: 2001-09-18
Classification: G11B

Abstract:
An optical disk apparatus for reproducing information from an optical recording medium, comprising:a light emitting unit that focuses a light beam onto the optical recording medium;a detecting unit that detects the light beam reflected by the optical recording medium;a processing unit that processes a signal generated by the detecting unit and outputs a processed signal that reproduces the recorded information;wherein the optical recording medium has reproducible information formed as mark arrays which have an optical phase difference with respect to adjacent portions of the mark arrays;the light emitting unit focuses the light beam along a line shifted away from the center lines of the mark arrays by a predetermined distance in a radial direction with respect to the center of the optical recording medium;the detecting unit has a detecting surface which is divided into at least two detecting areas by at least one divisional line parallel to the center line of the mark arrays;the processing unit is capable of computing the difference between and the sum of signals originating in the detecting areas, and outputs as the processed signal one or the other of those computed values to reproduce information of the mark arrays in accordance with a characteristic of the optical recording medium wherein the processing unit outputs as the processed signal the difference signal in the case when the optical recording medium has the characteristic in which the predetermined distance is longer than a predetermined value, and outputs the sum signal as the processed signal in the case when the optical recording medium has the characteristic in which the predetermined distance is shorter than the predetermined value.