Kinescope beam current limiter employing automatic sequential control of image contrast and brightness to limit beam current

摘要

A beam current limiter for a kinescope responsive to video signals coupled to the kinescope via a video signal transmission channel comprises means for providing a control signal representative of the magnitude of kinescope beam current above a predetermined level. The control signal is related to the amount by which the beam current exceeds the predetermined level. When beam current exceeds the predetermined level by an amount within a first range of beam current, the control signal is coupled to the signal transmission channel to vary the peak amplitude of the video signal to inhibit beam current above the predetermined level. When beam current exceeds the predetermined level by a relatively greater amount within a second range of beam current, the control signal is coupled to the signal transmission channel to vary both the peak amplitude and the D.C. level of the video signal to inhibit beam current above the predetermined level.