| 摘要 |
PURPOSE:To prevent the fluctuation off white balance by performing the demodulation processing of a carrier chrominance signal and a subcarrier wave in an SECAM color video signal, and holding selectively the level of a part corresponding to the subcarrier wave, and changing the level of the output of a demodulating means according to the said level. CONSTITUTION:When a pulse (c) is outputted from a pulse generation circuit 1b, the part, corresponding to the non-modulated subcarrier wave of the output (b) of an FM demodulation circuit 6, is extracted by a gate circuit 14, and is supplied to a clamp circuit 17 and is held, and the signal (e), the level of which is equal to an offset component in the output (b), is supplied to a subtraction circuit 12, and components DR and DB, the offset components of which have been removed, (the signal obtained by emphasizing color difference signals R-Y, B-Y by the circuit with a prescribed emphasis characteristic) are outputted alternately at every other 1H. Simultaneously, the components DB and DR, the offset components of which are removed by the gate circuit 15 and the clamp circuit 18, are alternately outputted at every other 1H from the subtraction circuit 13, and are supplied to an SECAM switch circuit 7. Thus, the color difference signals R-Y, B-Y excluding the offset component are obtained.
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