Optical information recording/reproducing system including novel tracking system

摘要

PCT No. PCT/JP91/01737 Sec. 371 Date Oct. 13, 1992 Sec. 102(e) Date Oct. 13, 1992 PCT Filed Dec. 19, 1991 PCT Pub. No. WO93/12522 PCT Pub. Date Jun. 24, 1993.An optical information recording/reproducing system is disclosed in which optical information having guide grooves for tracking and information pits beforehand provided thereon is irradiated with a main light beam for the recording/reproduction of information and a pair of subsidiary light beams for the detection of tracking and the scanning loci of the centers of the subsidiary light beams are arranged on the optical information carrier on opposite sides of the scanning locus of the center of the main light beam, respectively, first and second means for generating electric signals having their amplitudes corresponding to the respective intensities of the subsidiary light beams reflected by the optical information carrier, third means for detecting a difference in amplitude between the electric output signals of the first and second means, fourth means for detecting Ac components of the electric output signals of the first and second means to detect a difference in amplitude between the AC components, and fifth means for selecting a detection output of the third means as tracking information when the subsidiary light beams scan a region on the optical information carrier where the information pits are not provided and selecting a detection output of the fourth means as tracking information when the subsidiary light beams scan a region on the optical information carrier where the information pits are provided.