VIDEO DRIVER CIRCUIT AND METHOD FOR AUTOMATIC GRAY SCALE ADJUSTMENT AND ELIMINATION OF CONTRAST TRACKING ERRORS

摘要

An apparatus (10) and method for the automatic setup of a CRT (12) operating point, or dc signal level (black), as well as the contrast, or gain level (gray), of a video display by sampling the CRT (12) signal level of the individual cathodes (28) and locking the dc signal level to a common dc setup reference and gain level to a value determined by a common contrast control signal and gain reference. An apparatus (10) and method in which a common brightness control (44) signal is modulated by a common contrast control (46) signal such that a brightness control pedestal is added to each video signal (40) path of a video display whereby picture black level does not change with contrast.