In Dr. Goldsmith's invention, which he made more than ten years ago, the viewing face of a kinescope is coated with hundreds of thousands of elements of primary color phosphors (luminous material)--red, green and blue. A full color picture is reproduced by exciting the phosphor dots with precisely controlled and rapidly scanning electron beams.
Such tubes were first shown publicly in Washington on March 29, 1950 in demonstrations of RCA's all-electronic compatible color television system. Research and engineering on tricolor kinescopes have been conducted by RCA Laboratories Division and RCA Victor Division since World War II.
Dr. Goldsmith's patent (No. 2,630,542) describes and claims the "shadowmask" feature whereby a perforated screen is mounted just behind the picture screen. The shadow-mask has one tiny perforation for each grouping of three primary color dots. The beam for exciting the red dots, for example, is made to pass through the perforation at such an angle that a red phosphor is illuminated and the other two are shadowed and unactivated.
One form of RCA tricolor kinescope has 200,000 perforations on the shadow-mask and a total of 600,000 phosphor dots, 200,000 for each color. The individual dots are indistinguishable at normal viewing distance. Every second, the entire screen is scanned 30 times, giving a continuous smooth moving picture in color.