| 摘要 |
PURPOSE:To obtain a pickup picture with high contrast ratio, broad lattitude and high fidelity by mixing a blanking pulse with a video signal, displaying switchingly the picture and exposing it. CONSTITUTION:A logic circuit 26 has NAND gates 27, 29 which are opened sequentially by a blanking pulse switching control signal from a CPU 16. The output pulse of a comparator 24 is inputted to the NAND gate 27 and an inverting signal to the output pulse of a comparator 25 is inputted to the NAND gate 29 and an exclusive OR signal being outputs of the comparators 24, 25 is inputted to the NAND gate 28. Each sequential output of the NAND gates 27-29 is ORed by a NAND gate 30 and an output of the NAND gate 30 is given to a grid G of the CRT display device 13 as a blanking pulse.
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