| 摘要 |
PURPOSE:To eliminate the unstable state of a servo due to a DC component, by converting a tracking error signal into two waveforms by sample holding, superimposing the both to increase the level. CONSTITUTION:A pit signal RF of a disc information plane is converted into a positive pulse waveform having a prescribed amplitude at a cmparator 20, inputted to a rising pulse generator 31 and a falling pulse generator 32, and rising and falling pulses generated at the generators 31, 32 are summed with a tracking error signal Te at analog switches 41, 42 respectively for sample holding. Both sample hold signals are added at an adder AD and a tracking error signal Te1 is detected. The output of the adder AD is inputted to a low pass filter LPF, a high frequency component included in the tracking error signal Te1 is eliminated, and a tracking servo signal Ts is outputted. |
