| 摘要 |
PROBLEM TO BE SOLVED: To correct an offset error of an error signal for servo control such as tracking, focusing, etc., during reproducing CD. SOLUTION: In a CD reproducing device doing servo control by adjusting output ration of a first and a second sensors by a gain control signal and servo- controlling by receiving an error signal from the output, a subtracter 7 is provided which holds the peak and bottom values 5, 6 of the reproduced RF signal and generates RF amplitude signal by performing a subtraction between these holding values. And, the offset error is corrected by sequentially increasing a gain control signal by▵Vs to positive or negative side centering the zero level, detecting a maximum value of the stored RF amplitude signal while fetching and storing a RF amplitude signal value from the subtracter 7 at every increase, and supplying thereat the gain control signal value to a sensor output ratio adjustment circuit 4.
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