Automatic diaphragm control device for a closed circuit television camera

摘要

A diaphragm control for a video camera is disclosed and controls the camera diaphragm in response to the camera video output. The camera video output signal is adjustably weighted to vary the value of the dark portions of signal with respect to the light portions through the use of a selective polarity invertible amplifier which holds the average signal strength constant as the weight of the light and dark portions is varied. The output of the polarity invertible amplifier is averaged and then compared with a reference intensity signal. The output of the comparator is used to control the camera diaphragm.