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Early Color Television Chromatic Television LaboratoriesIn 1951 Dr. Ernest O. Lawrence of the University of California, Berkeley proposed a single gun color CRT using vertical stripes of red, blue and green on the screen. Behind these stripes were vertical wires which could be charged with electrical energy to deflect the electron beam to each of the stripes, thereby creating a color picture. However, very high power RF (around 50 watts) had to be applied to the deflecting wires, and RF radiation from the tube caused interference with the receiver circuits.The university set up "Chromatic Television Laboratories" to commercially develop the system, in partnership with Paramount Pictures, who provided development funding. In 1951 Chromatic Television Laboratories began experimenting with using the CBS field sequential system with their Chromatron tube rather than the color wheel that had been used in all previous field sequential systems (information courtesy of Ed Reitan). Because the high power RF switching was done at a much lower rate than with the later NTSC system, the interference problem was minimized. Chromatic Television Laboratories built prototype PDF 22-4 Chromatron CRTs in 1952 and 1953, with a display area of 14 by 11 inches. In 1953 the coronation of Queen Elizabeth II was televised in color, using an experimental field sequential system developed by Pye and Chromatic Television Laboratories. A field sequential camera was used and the signal was broadcast over a UHF channel to Great Ormonde Street Children’s Hospital in London. Receivers used the Chromatron CRT. Here is a New York Times article from June 3, 1953 describing Paramount's involvement (courtesy of John Pinckney). Here are articles that appeared in Billboard about CTL.
The receiver used to view the coronation
The University eventually abandoned their interest in Chromatron, but Paramount continued development through the 50s and early 60s, possibly as a system for displaying film during editing, which meant that the RF interference did not present a problem. Paramount also attempted to perfect the tube for use in receivers, but the RF interference problem was never solved. See this article in Radio-TV Experimenter (Courtesy of Wayne Bretl). In 1966, Sony made a few prototype sets using their own version of the Chromatron. A similar approach was later used a similar concept in their very successful Trinitron tube. Invisible text to format smartphones. xxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxx xxxxxx xxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxx |
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