Patent ID: 6144625
Filing Date: 2000-11-07
Classification: G11B

Abstract:
An optical disc discriminating system adapted to discriminate a first group of optical discs each formed with information tracks having a predetermined depth and a second group of optical discs each formed with information tracks having a different depth, and to discriminate from the second group of optical discs a specific optical disc which has information tracks wobbled with a wobble signal having a predetermined frequency and prepits formed between adjacent tracks, the discriminating system comprising:a tracking error signal generating means adapted to generate a tracking error signal whose amplitude level varies with a depth of information tracks on an optical disc;a tracking servo means for directing a laser beam along an information track on the optical disc in accordance with the tracking error signal;a comparator adapted to compare the amplitude level of the tracking error signal supplied from the tracking error signal generating means with a reference level, with a tracking servo loop of the tracking servo means in an opened condition;a first discriminating means adapted to discriminate the first and second groups of optical discs in accordance with a result from the comparator;an extractor for extracting the wobble signal; anda second discriminating means adapted to discriminate the specific optical disc from the second group of optical discs, in accordance with an output signal fed from the extractor when the tracking servo loop of the tracking servo means is in a closed condition.