Methods Suitable for Television Color Kinescopes

This paper is the first of a series which covers Radio Corporation of America work on color-television cathode-ray picture reproducers (color kinescopes) for the home. Minimum reproducer requirements are here considered to be high-light brightness and resolution equal to or exceeding that achieved in the present United States black-and-white television system and large-area three-color fidelity which encompasses the major part of the horseshoe-like area of the chromaticity diagram of the International Commission on Illumination (ICI). Color phosphors with electron-beam excitation meet the requirements. One color-kinescope method, which requires the beam to be accurately positioned at all times during scanning on a screen of adjacent subelemental color-phosphor areas, has practical disadvantages. In a second method, using a similar type of kinescope, the beam position controls the color signal; although accurate scanning is not required, some of the disadvantages are the same. A third method, which uses adjacent complete picture images, optically combined, has little to offer over the use of three separate color tubes. A phosphor screen, whose color can be changed by a difference in electron-beam velocity or current density, has attractive features, but is not available in practical form. Methods of considerable interest are those whereby either the electron beam is electrically controlled at the phosphor screen for changing color or whereby shadowing techniques are employed to produce a direction-sensitive color screen.