Patent ID: 6181657
Filing Date: 2001-01-30
Classification: G11B

Abstract:
A reading system for reading a writable optical disc having an information writing track and a guiding track for introducing a laser beam to the information writing track, wherein the guiding track has prepit information recorded on a first pattern, said reading system comprising:a photodetector having at least a first photodetecting element and a second photodetecting element divided by a first line optically parallel with a radial direction of the disc for detecting reflected light of the laser beam reflected from the information writing track; andprepit information extracting means for extracting the prepit information recorded on the guiding track by subtracting an output of the second photodetecting element from an output of the first photodetecting element,wherein the disc includes prepit information recorded on a second pattern on a second guiding track radially adjacent a first track on which prepit information is recorded on the first pattern, and the second pattern is deflected from the first pattern with a predetermined phase difference to avoid interference with the first pattern.