| 摘要 |
PURPOSE: To provide a tracking control circuit capable of reducing an influence of a lens shift by using a single beam tracking method. CONSTITUTION: A tracking error signal is generated by arithmetically operating the difference between a 1st summation signal of 1st and 4th detector output signals and a 2nd summation signal of 2nd and 3rd detector output signals. Also, an amplitude of a 1st differential signal between the 1st and 4th detector output signals is compared with that of a 2nd differential signal between the 2nd and 3rd detector output signals, and the amplification factors of the 1st and 2nd summation signals are determined on the basis of the comparison result, respectively. Since the amplitude difference between the amplitude of the 1st differential signal and the 2nd differential signal represents a lens shift, the amplification factors of the 1st and 2nd summation signals are adjusted, and it is thereby possible to obtain a tracking error signal from which the influence of the lens shift is eliminated.
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