Aunc.3382 net.games utzoo!decvax!duke!unc!wm Sat May 1 15:10:42 1982 Re: Third method of color presentation Concerning the index tube, it is alive an well in Japan (where else?) Except that the details have changed a little. Instead of a wire strip between each color there is a forth phosphor band so the tube is coated red-green-blue-uv where uv emits an invisible ultraviolet pulse back toward the neck of the tube instead of toward the viewer. This uv pulse is detected by a photomultiplier near the neck of the tube and is used to keep a phase locked loop on track for switching between the signals for the three real colors. The chief advantage of this type of tube is that since it has no metal shadow mask to eat up most of the beam power, this tube uses up no more power than a B&W tube. Naturally the first use of this tube has been to develop a portable color tv the same size as currently available B&W jobbies that uses no more power but has a remarkably good picture. As I recall Panasonic was doing the development. I have also heard a rumor that it is the basis for the hi-res TV work that Sony is doing because, since the strips can be non-uniformly spaced (the feedback loop keeps the colors converged properly) the tube is much easier to manufacture than a 1000 line shadow mask monitor. In fact the only true 1000 line monitor (one that really has enough lines of triads to really do 1000 lines) I have ever heard of is one manufactured by SRL (or something like that) that sold for over $25k and had to be converged every few minutes. Before anyone flames back at me for anything I have said: A quick tv monitor quiz, do you know what the "kell factor" for CRT's is? One more thing, there is still another way to get color out of a television, using a black and white tube no less (I am not counting giant color wheels in front of the set!) I can't remember the name for it, but it involves modulating the brightness of the image to product color. You can duplicate this yourself by coloring a disk half black and half white, and then putting black lines on the white half of the disk using a compass that are of various lengths and distances from the center of the disk. Then spin the disk and you will see color. There were various experiments with this method, and it was even a contender for the color TV standard since it would not require any modification of the many already existing b&w televisions. Of course when the television manufactures found out that there was a way to do color that would require everyone to get a new, expensive hunk of electronics and glass (and even produce X-rays!) you know what happened next. Some people might remember years ago some company (I think it was 7-up) made some commercials that could be seen in color on b&w sets using this method. They showed them during one episode of "Combat". Anyone else remember seeing those? (sorry for the length of this, but it is interesting to *me*) Wm Leler duke!unc!wm ----------------------------------------------------------------- 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.