| 摘要 |
PURPOSE:To reduce the numbers of external circuits and pins of an IC circuit and to stabilize the operation by providing two sampling hol circuits which are alternately subjected to sample-and-hold of a reproduced line-sequence color difference signal at every 2H and a voltage comparator which compares output voltages of these circuits with each other. CONSTITUTION:Two sampling hold circuits 61 and 62 which are alternately subjected to sample-and-hole of the signal at every 2H and a voltage comparator 7 which compares voltages of outputs (f) and (g) of circuits 61 and 62 with each other are provided. Consequently, only the DC potential difference at every 1H is detected independently of the variance of DC potential due to the difference of the color difference signal. Therefore, the capacity for elimination of DC variance is unnecessary, and an HPF is unnecessary because edge detection is no performed. Thus, the numbers of external circuits and pints of the IC circuit are reduced and the influence of noise is reduced to stabilize the operation.
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