| 摘要 |
PROBLEM TO BE SOLVED: To provide a tracking control apparatus and method based on a 1-beam method which enables adaptively setting of the optimum servo coefficient for each optical disc. SOLUTION: A difference (E-F) between signals E and F and a sum (E+F) thereof from terminals 11 and 12 are found by an subtraction amplifier 13 and an addition amplifier 14 to find a standardized push/pull signal NPP =(E-≠)/(E+F) with a division circuit 20. The amplitude of the signal is detected by a signal amplitude detection circuit 30 and sent to a coefficient calculation circuit 50 through an A/D conversion circuit 40 to set a tracking servo coefficient K according to the amplitude of the NPP signal. A moving value signal CSL of an objective lens generated by top hold circuits 65 and 66 and a subtraction amplifier 70 is multiplied by the coefficient K using a multiplication amplifier 80 to make a cancel signal, which is subtracted from a pushpull signal PP by a subtraction amplifier 99. Thus, the offset of the signal PP is cancelled to obtain the optimum tracking error.
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