Ultraviolet powers pixels

Researchers from the University of Cincinnati and Extreme Photonix, LLC have devised a flat-panel screen that transmits light 10 times more effectively than traditional liquid crystal displays.

The technology could lead to a wide range of efficient computer and television screens, according to the researchers.

The researchers' method uses lightwave coupling, which channels light from a plane inside a sheet of plastic to pixels that emit the light from the sheet's surface.

The researchers' device uses inorganic ultraviolet light-emitting diode as a light source, but uses organic color conversion media to convert the invisible ultraviolet photons to visible red, green and blue light. The organic color conversion media is very efficient at emitting the ultraviolet light it absorbs as longer-wavelength visible light.

The device emits light at a projected efficiency of 20-30 lumens per watt, according to the researchers. Liquid crystal displays, in comparison, have an efficiency of two to three lumens per watt.

The pixels are switched on and off by selectively changing the refractive index of the plastic sheet's surface to allow or block the ultraviolet light inside the sheet from passing through to the pixels.

Some lower-resolution applications could become practical in two to three years; larger, denser arrays could become practical in five years, according to the researchers. The researchers presented the work at the Society for Information Display (SIDS) International Symposium 2004 in Seattle, Washington, May 23 to 28.