| 摘要 |
PURPOSE:To prevent the flow of a picture reflected on a monitor equipment and so on even when plural TV cameras are switched by separately eliminating a horuzontal synchronous signal and an equivalent pulse and so on included in the video of the plural TV cameras and obtaining an internal synchronous signal which is stable and synchronized with an external signal. CONSTITUTION:When the external synchronous signal from the other TV camera is inputted, the horizontal synchronizing signal and the equivalent pulse from the isolation circuit 1 of a synchronous circuit is compared with the internal synchronous signal of the camera outputted from a synchronous signal generator 6 by a phase comparator 5. The horizontal synchronizing signal outputted by the comparator 5 is turned on by a switch circuit 7 based on a timing from the generator 6 and is subjected to sample-and-hold. By this sampling, the equivalent pulse recept the timing of the horizontal synchronous signal in the equivalent pulse separated by the circuit 1 is eliminated. Besides, the sampled signal is supplied to a VCO circuit 9 through an LPF circuit 8 and by this output, the generator 6 is controlled and the synchronous signal (b) synchronized with the external video signal (a) is outputted.
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