| 摘要 |
PURPOSE:To obtain a video signal with excellent color balance, by controlling the gain of a luminance signal automatically even when an object is darker than when an iris is opened fully. CONSTITUTION:A luminance-signal detector 7 detects the level of a luminance signal, and an auto iris 8 controls an iris automatically in accordance with variation in level, setting the best quantity of light. A manual changeover switch 10 is placed at a high-gain side and when the iris 8 is opened fully, an iris control voltage is detected. The luminance signal is supplied automatically to a luminance-signal gain control circuit 12 by the detection signal through the automatic changeover switch 11, setting a high gain. |
