COLOR VIDEO CAMERA CIRCUIT

PURPOSE:To obtain excellent picture quality even when the color temperature of lighting deviates from standard color temperature of 3,200 deg.K by providing a brightness signal correcting circuit which controls a brightness signal level by using a white balance control signal. CONSTITUTION:A negative feedback loop is so formed that analog voltages obtained by a converting the counted value of an up/down level counter circuit 13 through DA converters 19 and 20 are used as control voltages of variable gain amplifiers 2 and 3. Then, a blue variable gain amplifier 2 and a red variable gain amplifier 3 are brought under gain control so that color difference signals B-YL and R-YL are zero, thereby adjusting white balance automatically. A brightness signal correcting circuit 21, on the other hand, slices the excessive part of the difference signal between the gain control voltage and brightness signal YL outputted by the DA converters 19 and 20 of the up/down level counter 13 with a constant slice level outputted from slice circuits 24 and 25. Then, the remaining color difference signal is added to the brightness signal YH to add or subtract the brightness signal YH, thereby correcting the brightness. Consequently, the brightness is adjusted to the standard brightness of the NTSC system.