AfterDawn: Glossary

Plasma display

A Plasma display or PDP is a flat panel display now commonly used for large television displays typically 37-inches and above. Many tiny cells compressed between two panels of glass hold the inert mixure of neon and xenon. The gas in the cells is electrically turned into plasma which excites phosphors and create the light you see on the display.

The plasma display was invented at the University of Illinois at Urbana-Champaign by Donald L. Bitzer, H. Gene Slottow and a graduate student Robert Willson in 1964 for the PLATO computer system. The screen was monochromatic and appeared in either shades of green or yellow. The initially met their early demise in the late 1970s because the classic CRT design was cheaper to design and manufacture.

In 1983 IBM introduced a 19-inch orange-on-black monochromatic display which was capable of displaying four virtual machine terminal sessions. The factory responsible for that was transferred in 1987 to a startup company called Plasmaco, founded by Dr. Bitzer's former students and later purchased by Matsushita in 1996. In 1997, Pioneer, a company under Matsushita, began selling the first full color plasma displays to the public. Current plasma displays range in sizes as low as 21-inches to the monstrosity unveiled at the 2006 Consumer Electronics Show in Las Vegas measuring an astounding 103-inches, developed by Matsushita.

How does plasma work? The xenon and neon gas in a plasma television are contained in hundreds of thousands of tiny cells positioned between two plates of glass. Long electrodes are also sandwiched in this mix in front and behind the cells. The electrodes along the back are address electrodes and transparent display electrodes insulated by dielectric material and covered by magnesium oxide reside in the front. Circuitry charges the electrodes where they cross paths along a Cell and creates a voltage difference between the front and the back which causes the gas to ionize and form plasma. As the gas ions rush to the electrodes and collide, they create photons. In color displays, the back of each cell is coated with a phosphor. The ultraviolet photons emitted by the plasma excite these phosphors to give off the colored light that we see.

Every pixel is made up of six sub-pixels which house different colored phosphors. One sub-pixel has a red light phosphor, one has a green and another a blue light phosphor. These colors blend together to create the overall color of the pixel.


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