Patent ID: 6147952
Filing Date: 2000-11-14
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 so as to trace 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 includes a detector having a detecting surface which is divided into two segments along a first line which is shifted a certain distance from the center of a zero-order diffracted beam spot being guided over the detecting surface; andthe processing unit computes the difference between the signal values detected in the segments, and outputs this difference as the processed signal.