Optical tracking system for an optical recording arrangement with plurality of beams
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United States of America Patent
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May 12, 1992
Grant Date -
N/A
app pub date -
Jan 2, 1990
filing date -
Apr 20, 1988
priority date (Note) -
Expired
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Abstract
An optical recording device which writes and reads data by radiating laser beams from an optical head onto an optical recording medium. A diffraction grating is provided on the optical head and a plurality of laser beams are generated. Some of the laser beams are positioned on a track guide on the above-mentioned optical recording medium. Some of the other laser beams are positioned on another track guide and a plurality of tracking beams are thus constituted. The optical recording device is also provided with a tracking detection circuit for outputting a tracking error signal indicating the difference between the amounts of reflected light to a photo detector which receives light reflected from the above-mentioned optical recording medium for tracking beams and for switching the above-mentioned tracking beams used for tracking. The plurality of tracking beams enables tracking to be performed even when a track guide has defects by switching tracking beams, thereby improving tracking reliability.
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