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-   -   designing the tri-color crt (http://www.videokarma.org/showthread.php?t=47085)

oldtvman 09-08-2005 08:13 PM

designing the tri-color crt
 
I read an article a long time ago that one of the physists that helped design the tri-color crt used sugar cubes painted with the three light primary colors to help configure the design still used today in a 3 gun color crt. Any one heard the story?

old_tv_nut 09-08-2005 09:24 PM

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The tube you are describing is not the modern one, but one invented by John Logie Baird before WWII. It had the guns off at three very different angles. This would work with a screen made up of pyramids (half cubes). He proposed a variation that used a two sided transparent screen with two colors on a ridged surface on one side and the third color on the back. Either way, the mini-pyramids or ridges have different sides that are each illuminated only by one gun. No shadow mask needed, but the keystone correction would be horrendous. Here is a sketch from "Elements of Television Systems", George. E. Anner, Prentice Hall, 1951. I know I have seen a photo of an experimental tube with widely spaced guns, but can't put my hands on it right now

old_tv_nut 09-08-2005 10:12 PM

October 1951 Proceedings of the IRE shows a sketch of the pyramidal screen on p.1184, and attributes these later developments of Baird's idea in various forms to C.W. Geer, Alfred N. Goldsmith, and unspecifed inventors at Dumont.

Alfred N. Goldsmith was the editor of the Proceedings at this time. Goldsmith got a patent for reducing the blue bandwidth in 1943, so yes, he was involved early on in color TV systems.


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