Chromatron
The Chromatron is a color television cathode ray tube design invented by Nobel prize-winner Ernest Lawrence and developed commercially by Paramount Pictures, Sony, Litton Industries and others. The Chromatron offered brighter images than conventional color television systems using a shadow mask, but a host of development problems kept it from being widely used in spite of years of development. Sony eventually abandoned it in favor of their famous Trinitron system using an aperture grille. History Color television Color television had been studied even before commercial broadcasting became common, but it was only in the late 1940s that the problem was seriously considered. At the time, a number of systems were being proposed that used separate red, green and blue signals (RGB), broadcast in succession. Most systems broadcast entire frames in sequence, with a colored filter (or "gel") that rotated in front of an otherwise conventional black and white television tube. Because they broadcast separate signals for the different colors, all of these systems were incompatible with existing black and white sets. Another problem was that the mechanical filter made them flicker unless very high refresh rates were used. In spite of these problems, the US Federal Communications Commission (FCC) selected a sequential-frame 144 frame/s standard from CBS as their color broadcast standard in 1950. RCA worked along different lines entirely, using the luminance-chrominance system. This system did not directly encode or transmit the RGB signals; instead, it combined these colors into one overall brightness figure, the "luminance". Luminance closely matched the black and white signal of existing broadcasts, allowing it to be displayed on existing televisions. This was a major advantage over the mechanical systems being proposed by other groups. Color information was then separately encoded and folded into the signal as a high-frequency modification to produce a composite video signal – on a black and white television this extra information would be seen as a slight randomization of the image intensity and just appear blurry, but the limited resolution of existing sets made this invisible in practice. On color sets, the signal would be extracted, decoded back into RGB, and displayed. Although RCA's system had enormous benefits, it had not been successfully developed because it was difficult to produce suitable display tubes. Black and white TVs used a continuous signal and the tube could be coated with an even painting of phosphor. With RCA's system, the color was changing continually along the line, which was far too fast for any sort of mechanical filter to follow. Instead, the phosphor had to be broken down into a discrete pattern of colored spots. Focusing the right signal on each of these tiny spots was beyond the capability of electron guns of the era. RCA's early experiments used three-tube projectors, or mirror-based systems known as "Triniscope". Shadow masks RCA eventually solved the problem of displaying the color images with their introduction of the shadow mask. The shadow mask consists of a thin sheet of aluminum with tiny holes photo etched into it,