| 摘要 |
PURPOSE: A circuit for detecting a vertical synchronous signal of a display device is provided to separate the synchronous signal from input composite synchronous signals without having information about the frequency and polarity of the input composite synchronous signals. CONSTITUTION: A circuit for detecting a vertical synchronous signal of a display device includes a counter(300), a flag signal generator(310), and an RS flip-flop(320). The counter counts input horizontal and vertical composite synchronous signals to output a plurality of output signals. The flag signal generator receives the output signals of the counter and outputs the first and second flag signals until all the output signals have the same logic value. The RS flip-flop receives the first and second flag signals as set and reset inputs, respectively, to extract a vertical synchronous signal.
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