| 摘要 |
PROBLEM TO BE SOLVED: To provide a unit and a method for tracking control by a one-beam method while optimum servo coefficients can be adaptively set by optical disks. SOLUTION: The difference (E-F) between and the sum (E+F) of E and F signals from terminals 11 and 12 are found by a subtracting amplifier 13 and a summing amplifier 14 and a dividing circuit 20 finds a standardized push-pull signal NPP=(E-F)/(E+F). Its amplitude is detected by a signal amplitude detecting circuit 30 and sent to a coefficient calculating circuit 50 through an A/D converting circuit 40 to set a tracking servo coefficient K corresponding to the amplitude of the NPP signal. A multiplying amplifier 80 multiplies the movement quantity signal CSL of the objective generated by the top holding circuits 65 and 66 and subtraction amplifier 70 by a coefficient K to generate a cancel signal and a subtracting amplifier 90 subtracts it from the push-pull signal PP. Consequently, the offset of the subtracting amplifier 90 is eliminated and the offset state for the PP signal is canceled, and an optimum tracking error signal is obtained. COPYRIGHT: (C)2006,JPO&NCIPI
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