Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Patent
1997-11-17
1999-06-01
Tran, Thang V.
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
369 4437, 369 54, G11B 709
Patent
active
059094168
ABSTRACT:
The invention relates to a technique to detect lands and grooves formed on an optical disk, and is intended to provide a land/groove detecting apparatus capable of steadily obtaining track detection signals and land/groove detection signals. According to the invention, +1-, 0- and -1-order light beams obtained from a three-beam type optical head are received by a 6-divided optical sensor, and the 0-order beam is detected by optical sensor elements a, b, c and d of a 4-divided optical sensor while the +1- and -1-order beams are detected by two optical sensor elements e and f, respectively, on the two sides of the 4-divided optical sensor. The output signals of the optical sensor elements a, b, c, d, e and f are denoted by A, B, C, D, E and F, respectively. As a tracking error signal and a land/groove detection signal are calculated by equations TE=E-F and LG=(2.times.(A+B+C+D)-(E+F)), the land/groove detection signal LG is held at a zero cross point of the tracking error signal TE, and whether getting on a track has taken place on a land or on a groove is determined according to a polarity of the held land/groove detection signal LG, stable tracking error signals and land/groove detection signals can be obtained.
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patent: 5828634 (1998-10-01), Ohno et al.
Atsushi Saito et al., "1/8 Track Pitch Positioning Method for Optical Disk Drive", The Journal of the Institute of Electronics Information and Communication Engineers, Autumn Convention, C-384, Oct. 1994.
NEC Corporation
Tran Thang V.
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