Abstract: A method and apparatus for compensating the alternating electrical fields present at the front surface of a cathode ray picture tube wherein the high-voltage signal supplied to the high-voltage terminal of the tube is tapped to extract an alternating voltage signal therefrom, and the alternating voltage signal is inverted and amplified and then applied to a suitable external electrode placed in the proximity of the picture tube. The external electrode can be a framing band, an aquadag region or a ring electrode, among other things. Furthermore, combination of these electrodes can be employed.

Abstract: A system for the generation of a light intensity control signal for a video amplifier of a data display device is disclosed which is connected with a video signal line and a pulse generator. When displaying characters composed of horizontal lines and vertical rows of points on a screen, the lines display a higher brightness than the points. The disclosed system derives from the video signal an analog light intensity control signal for the video amplifier with which the light intensity of the points is readjusted. The system includes a detector device connected with a video signal line, the detector device identifying the signal sequence associated to a point, a line or, a blank and a converter which derives a light intensity control signal therefrom.