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Abstract

A tracking method for reading/writing data with respect to an optical recording medium having clock tracks each formed of clock bits of optical patterns and data tracks. The method is carried out by irradiating from an optical lead side a pair of light beams onto a pair of clock tracks, with the beams so deviated from each other in a direction of relative movement of the optical head with respect to the medium that beam detection signals may have a difference in phase therebetween. Reflections of the respective light beams from the clock tracks are detected and a difference signal between reflections determined from the detection signals is obtained. A tracking-error signal from the difference signal is extracted and a zero-crossing point of the difference signal then is detected to extract a clock signal.

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First Claim