| 摘要 |
A reading circuit with improved accuracy for an optical disk apparatus, which includes two separate systems for processing the read-out signal from the photo-transducer. In the first system, the read-out signal is differentiated and then a zero-level detector generates a binary signal to indicate whether the differentiated signal is positive or negative, whereby the binary signal indicates whether the edges of the read-out signal are rising or falling. The second system is a pit detecting circuit which generates a pit detecting signal by comparing the read-out signal with a fixed reference voltage, the pit detecting signal thus indicating the spacing between pits in the read-out signal. An AND gate combines the pit detecting signal with the inverse of the binary signal, generating pulses in close synchronism with the rising edges of the pits on the optical disk, and these pulses are shaped so as to correspond very closely to the recorded information. In another form of the invention, the pit detecting circuit includes a second differentiator for differentiating the first differentiated signal to generate a second differentiated signal, the latter being compared with a fixed reference voltage, providing further improvements in accuracy. |
