| 摘要 |
PURPOSE:To eliminate almost the delay of discrimination in comparison with the discrimination by frequency difference with a filter by comparing a potential just after a clamped horizontal blanking period with a reference value so as to discriminate kinds of a color difference signal. CONSTITUTION:A frequency division circuit 27 inputs a pulse MD at each horizontal scanning period and divides it into 1/2, a clamp pulse generating circuit 30 is triggered in synchronizing with an output signal of the circuit 27, a clamp pulse CP is outputted in the horizontal blanking period HBLK and a clamp circuit 22 clamps a line sequential chrominaice signal. A sampling circuit 23 samples said signal at a period just after the clamped period HBLK at least among the periods HBLK. A reset pulse generating circuit 25 compares each sample value with a reference value and when the value satisfies a prescribed condition, a reset pulse RP is outputted so as to reset the circuit 27. Thus, a discrimination signal ID is obtained from said circuit 27. |
