| 摘要 |
PURPOSE:To obtain a stable reproducing signal and to perform confirmatory reproduction satisfactorily by detecting the tracking error of succeeding light fluxes for the confirmatory reproduction, and changing the amplification degree of a signal in proportion to the size of a detected error signal. CONSTITUTION:A photodetector 21 is provided with two photodetecting parts 21A and 21B, and their outputs are converted to voltage signals at a current and a voltage converters 31 and 32, and are added by an adder 34, then, a detection signal for reproduction is generated. Meanwhile, the output in which the difference of the output is taken at a differential amplifier 33 and changed to a tracking error signal is inputted to an amplifier 36 after being changed to the one with the size of the error signal at an absolute circuit 35. The amplifier 36 is a gain-variable type amplifier, and whose amplification degree can be varied in proportion to the error signal. Therefore, the lowering of the signal level of the detection signal from the adder 34 can be compensated at the amplifier 36 proportionally to the error signal. In such a way, it is possible to always obtain the stable reproducing signal, and to perform the confirmatory reproduction satisfactorily. |
