Ahouxn.137 net.games utzoo!decvax!harpo!ihnss!houxi!houxn!piovano Fri Apr 30 09:10:26 1982 Third method of color presentation In addition to the shadow mask tube and the beam penetration methods of generating color, there is a third method that no one seems to have mentioned. This is the Goodman radiation index tube. It has a single gun for all three colors and no shadow mask. The phosphors are laid out on the inside surface of the picture tube in vertical strips in triplets of red, blue and green with a very thin strip of wire or metal between each color strip. As the electron beam scans the surface it causes a small pulse of x-rays to be emitted when it crosses color boundaries by impinging on the wire or metal strip. This pulse is picked up by a sensor at the back of the tube and outputs a pulse to indicate a change of color. The electronic circuitry is then responsible for changing the signal fed to the electron beam. Although the tube was usually used in raster scan systems, it can also be used in vector stroke systems by having the circuitry keep track of the horizontal direction and switching to the appropriate color. I do not know if any one still uses the index tube for anything at all nowadays, but since every one on the net seems to have forgotten it, I thought I'd resurrect it. Larry J. Piovano Bell Telephone Laboratories Freehold, N.J. ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.