Field Emission Displays - FEDs - phosphor problems
For many years phosphors for fluorescent lamps and televisions have quietly improved. For lamps, they are good at converting the ultraviolet (UV) light from a mercury glow discharge into visible light. Television phosphors take in 20kV electrons and give light of either red, green, or blue.
Field emission displays will be operating at voltages of 50 - 500V. While it would seem obvious that 20kV electrons would be more damaging to the phosphor particles than 500V electrons, that turns out to be wrong. At low voltages, the phosphors behave differently. The blue phosphors especially have short lifetimes, and low efficiency.
It appears that this is the most serious problem facing the FED companies. There are also difficulties with low yields of the emission cathodes, poisoning of the cathodes by sputtered materials from the phosphors, and high manufacturing costs. These other problems can probably be solved faster than the phosphor problems.
Different companies are taking somewhat different approaches which can best be characterized by their chosen operating voltages. Pixtech is aiming at the low voltage end. SI Diamond, and Micron at the higher end. The various other players I'm not sure about.
BTW- I keep seeing Pixtech listed as based in Santa Clara, but I can assure you that most of their people speak French as a first language. I'm not sure where the company is really based.
It appears that all of the FED (and NEA) companies will be facing problems with phosphors. My impression is that LCDs will continue to dominate notebook computer monitors for a while. Plasma displays will move into the television market quickly, and then work to achieve HDTV and computer monitor resolutions.
High performance CRTs for special applications are getting much better, but Sony's flat deflected-electron-beam CRT has been discontinued.
Perhaps one of the technical analysts out there could evaluate Sony, Matsushita, NEC, and Fujitsu to see if any of them might significantly increase their stock value with a strong showing in the large, flat TV market.
-bob mackey
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