Optical disk apparatus for reproducing information from an optical recording medium

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 three segments separated by a first line and a second line parallel to the first line, wherein the first and the second lines are each shifted a certain distance and in opposite directions from the center of the zero-order diffracted beam spot on the detecting surface;
• and
• the processing unit computes the difference between the signal values detected in the segments, and outputs this difference as the processed signal.

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 eight segments separated by first, second and third lines parallel to each other and a fourth line perpendicular to the first, second and third lines, wherein the third line passes through the center of the zero-order diffracted beam spot on the detecting surface;
• and
• the processing unit computes the difference between the signal values detected in the segments, and outputs this difference as the processed signal.