Plasma Display Panels (PDPs)
There were four PDPs exhibited at the SID conference:
Plasmaco (recently purchased by Matsushita), Sony, Fujitsu, and NEC.
All four panels appear ready to compete in the television market, and that is where they will appear this fall in Japan. I spoke with reps from each of the companies, and all said more or less the same thing: they will introduce 42" screens this year in Japan with about VGA resolution (640 x 480).
To my eyes, the Fujitsu screen had the best natural colors, and good contrast. It also ran the coolest. The Plasmaco and NEC screens were tied for a close second. The Sony suffered from slightly lower contrast.
A PDP uses the same operating principles as a fluorescent light bulb to give efficient conversion of electricity into light. In the AC plasma displays, an insulated electrode is placed over a phosphor lined trough. When an AC voltage is placed across the front and back electrodes, the neon/xenon gas is exited and gives off ultraviolet light (DC plasma operation is essentially similar, but there are some important differences in the structures). The UV light scatters strongly in the gas mixture, but eventually hits the phosphor, exciting a visible photon. In order to maintain color purity and high contrast, there are barriers between adjacent troughs. Along the troughs, contrast is not as sharp, so resolution is limited to TV applications at this time. Computer monitors may come along in a year or so. One of the Fujitsu engineers from Japan hinted that high resolution 21" screens might be available in 1997. Also, look for high-visibility demos at places like Fry Electronics in San Jose.
The Plasmco and probably others as well benefit from a self-aligning structure. Vertical troughs are in the back surface, horizontal rows are in the front surface, and wherever they happen to cross is where the pixels are. Thermal expansion or misalignment will cause no loss of color purity, or other image degradation.
It would appear that these screens can be manufactured at low cost. CRTs are built extremely cheap. The actual manufacturing cost of the display portion of a common 21" television is under $10, so they won't be cheaper than CRTs anytime soon, but I see no reason why they can't approach similar costs once the factories are paid for. In very large sizes, the PDPs will be cheaper due the reduced amount of glass used. This will be partially offset by higher costs in drive electronics. Some will be fully digital with discreet pixel values individually addressed.
There is very little flicker due to a memory effect inherent in the plasma. Once a pixel is turned on, it stays on until turned off. Partial brightness is controlled by turning on the pixel for some fraction of the frame refresh period.
As an investor, I'm sorry to see that the one small company involved in PDPs has been purchased in its entirety by Matsushita. With Sony, NEC, Fujitsu, and Matsushita the main players, no one will experience profound growth, except perhaps the US-Japan trade deficit.
As an inventor, I can see that the competition is pretty tough, and has a big headstart.
-bob mackey |
