Synchronizing circuit and counter in image pickup system

摘要

The horizontal synchronous signal and the vertical synchronous signal included in a composite synchronous signal which is output from one TV camera are separated from the composite synchronous signal. A plurality of TV cameras are controlled on the basis of the horizontal synchronous signal and the vertical synchronous signal so as to produce synchronized video signals from the plurality of TV cameras. These synchronized video signals are easy to compound. In the blanking period of the vertical synchronous signal, the rise period of the synchronous signal is 1/2 of the period of the vertical synchronous signal. Pulses are eliminated alternately in the blanking period by a half killer circuit including a counter and a decoder and having a simple structure, thereby generating a horizontal synchronous signal appropriate for driving the TV cameras. The counter composed of Johnson counters connected in multiple stages reduces the amount of current flowing to the counter, thereby eliminating the deleterious influence on the TV cameras.