TV camera automatic black and white balancing - is applied to amplifier of TV tube and adjusts signal levels to neutral white and green channels

摘要

The illumination to the camera tube(s) and/or signal generation in the colour TV camera is interruped for black balancing. During this period signal levels in the colour channels are adjusted to the levels of neutral white or green channels serving as reference signals. This is performed by control elements controlled by signal difference. A difference voltage derived from the signal difference is converted into a digital signal and stored. It is used for the element control in the sense of the signal difference reduction. The circuit components include a comparator (11), counter (13), digital/analogue converter (21) and buffer unit (31).