| 摘要 |
PROBLEM TO BE SOLVED: To perform correct tracking control without leaving, as offset of a tracking signal, a variation in reflectance due to presence/absence of a record mark of a signal track scanned with a succeeding sub-beam by generating a tracking error signal based on a differential push-pull method. SOLUTION: A tracking error signal generation method comprises: generating a division signal obtained by dividing a succeeding sub-beam push-pull signal (b1-b2) by a whole light quantity signal of the succeeding sub-beam; correcting the division signal to a signal level equal to the preceding sub-beam push-pull signal generated from each light receiving output of a preceding sub-light receiving region corresponding to the preceding sub-beam, then adding the succeeding sub-beam push-pull signal and the preceding sub-beam push-pull signal to generate an addition sub-beam push-pull signal((b1-b2)+(c1-c2)); adjusting the addition sub-beam push-pull signal and a main beam push-pull signal (a1-a2) generated from each light receiving output obtained from a main light receiving region corresponding to the main beam to an equal signal level, then subtracting the adjusted addition sub-beam push-pull signal from the main beam push-pull signal to generate a tracking error signal ((a1-a2)-G1x[(b1-b2)+(c1-c2)]) based on a differential push-pull method. COPYRIGHT: (C)2006,JPO&NCIPI
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