Videocolor, S.a.

Andre Lavigne

The blocking voltage of an electron gun is corrected by periodically removing an input video signal and driving a cathode with a DC stabilizing voltage. A pulse perturbation is impressed upon a control grid and the cathode momentarily conducts more heavily to exceed a predetermined threshold corresponding to the limit of a black CRT picture. A feedback loop detects a response signal from the perturbation of cathode current and stores the response signal in a memory, the latter determining the corrected blocking voltage during normal operation of the gun.

Method and apparatus of automatically processing and correcting the

Apparatus is disclosed for generating a blanking voltage for electron guns in cathode ray tubes, as used, for example, in color television displays. Apparatus utilizes circuitry including a video voltage amplifier having a control input. A feedback loop, connected between the junction of the cathode and video voltage amplifier output at one terminal, and the control input at the other, modifies the blanking voltage in response to samples of the cathode current taken when the video signal is zero.

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Montrouge, France

Andre Lavigne