Mike Carrell wrote: > There is a misunderstanding of the nature of DLP technology. The active > element is an array of tiny mirrors created by silicon machining techniques, > one for each pixel. Each mirror can be tilted by a small angle under control > from a TV signal. That tilt determines wihether the light falling on it goes > to a location on the screen or to a dump. The average intensityof each pixel > is determined by the fraction of time the mirror illuminates the screen. The > individual mirrors do not scan, they only switch light to or away from one > location on the screen. The optics, once fixed, are quite robust. The only > variable is the lamp. which has finite life and must be changed.
Exactly right. About 10 years ago, when the practical application of DLP was in its infancy, I was asked to consult about methods of improving light usage in DLP systems. My suggestion, which sounds sophisticated, but is in fact very simple, was as follows: Each mirror facet, instead of being a plane mirror would be etched as a fresnel zone plate, the diffraction equivalent of a lens. At the focus of the zone plates would be a holographic optical element (HOE) that would represent a secondary pixel array much finer than the original mirror zone plate array. The light could then be directed to the proper section of the HOE to illuminate the pixels as needed. Hardly any light would be wasted except for losses due to having an extra element in the system. Naturally, an all black picture would still represent 100% light loss, but on the average, this system would require a much lower power lamp for the same image brightness. This sounds all very well and good, but the digital processing power necessary was not available at consumer prices at the time. As we all know, processor speed and power has increased geometrically in the last decade. I'm still waiting for that call-back. How may Rs in fat chance? M. _______________________________________________ Join Excite! - http://www.excite.com The most personalized portal on the Web!
