| 摘要 |
PURPOSE:To eliminate the fluctuation of a video signal, by comparing the voltage difference between a signal and its peak value and that between this peak value and a dark current and taking the result of comparison as a read-out signal. CONSTITUTION:A sample holding circuit S2 is reset by a start pulse P2 and a dark current is held in a sample holding circuit S1. Further, when a video signal esi is added, a transistor Q2 is turned on by the peak voltage and a peak value eri is held at a capacitor C4. Then, the voltage difference between a peak value eri being the output of a subtractor A2 and the signal esi, and a voltage divided value eta(eri-eBO) of the voltage difference between the peak value eri being the output of a subtractor A3 and a dark current output eBO, are compared at a comparator C2. Binarized output signal eoi can be obtained by reading in the compared output to a flip-flop F3 at a clock P1. |
