Archived posting to the Leica Users Group, 2010/08/10
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On 08/10/2010 08:20 PM, Lawrence Zeitlin wrote: > Rei, > > Indeed you are right. I'm always amused when bad guys in movies trigger off > a state of the art nuclear device and the time to detonation is shown on > Nixie tubes, a half century old technology. My vague recollection was that the display in the Goldfinger Fort Knox nuke was composed of three Nixies (you remember, that countdown that ultimately stops at 0-0-7), but after careful reviewing this is not the case. The digits in the film were well-formed like Nixies and were definitely stacked in depth like Nixies, but the illumination was clearly not the continuous cathodes of the Nixie. Google and Wikipedia, as usual, were my friends: ".. the atomic bomb countdown display in Goldfinger was another technology from the same period: edge-lit lightguide readouts. These use small incandescent light bulbs at the edges of plates of clear plastic stacked together with narrow gaps between them. In each plate, a single numeral is formed from a series of "dimples" drilled from the back side. The plates are assembled in a holder so that their edges are not easily seen. A bulb shining in one edge will cause little or no light to be emitted from the smooth faces, due to the optical phenomenon known as "total internal reflection". However, the drilled dimples are at a less obtuse angle to the approaching light rays, and have rough surfaces, therefore scatter the light more nearly perpendicular to the plane of the plates' front surfaces, where it can escape to be seen by the viewer. Thus, the digits appear as a group of bright white dots apparently floating in a small dark space without any visible support. Contrast this with nixies, which display figures as continuous lines broken only by the fine anode mesh and the lines of other digits which may lie in front of the lit digit, always glow in the pink-orange-red range, and are usually placed behind red or dark orange filters to enhance contrast. Although the white(ish) light of edge-lit displays could be filtered to any desired color, historically this was almost never done." http://en.wikipedia.org/wiki/Talk%3ANixie_tube#Were_these_in_Goldfinger.3F Here's a guy who made a clock out of edge-lit display technology and LED illumination: http://users.rcn.com/ted.johnson/erc_clock.htm YLSNED (You learn something new every day.) -rei