Voltage-Controlled Multicolor CRT Phosphors: Preparation and Characteristics

Since the range of electrons in a solid is a function of their initial energy it is possible to construct high‐resolution multicolor cathode‐ray phosphor screens in which the color is determined by the accelerating potential. A nonluminescent layer of controlled thickness is formed upon the surface of each grain of a green or cyan phosphor. This coating is prepared either by the diffusion of a killer impurity such as cobalt from the surface into the bulk or by the homogeneous precipitation of undoped upon each phosphor grain. The coated phosphor is then intimately mixed with any efficient standard red emitting phosphor such as or . A screen consisting of an intimate mixture of two component phosphors is then deposited by the same method used to prepare monochrome screens. Four distinct colors, useful for information display, can be observed in the red‐green system. Quite acceptable two‐primary‐color television pictures have been demonstrated in the red‐ cyan phosphor system.