Reported February 2006

BACKGROUND: Researchers at Rensselaer Polytechnic Institute are developing a 20-foot by 15-foot demo room to display a light-emitting diode (LED) lighting tile that can be snapped into place like sheetrock to form ceilings and walls. Though this tile is still a prototype, LED technology is already used in exit signs and traffic signals, as well as digital clocks, plasma TV screens and remote controls. Researchers hope the demo room will demonstrate the advantages of LED lighting for other applications.

HOW IT WORKS: LEDs are tiny light bulbs that fit into an electrical circuit, but are lit solely by the movement of electrons in a semi-conducting material. A diode is the simplest semiconductor device. Bonding a section of a positively charged material to a section of a negatively charged material with electrodes on each end, causing it to only conduct electricity in one direction whenever a voltage is applied to the diode. Electrons move in a series of fixed orbits around the nuclei of atoms. Whenever an electron absorbs extra energy from the added voltage, it jumps to a higher orbital, and when it returns to a lower orbital, it emits the extra energy as a photon -- a particle of light. LEDs are specially constructed to emit a large number of photons, unlike ordinary diodes, in which the semiconductor material absorbs most of the light energy before it can be released. LEDs are also housed in a plastic bulb to concentrate the light in a particular direction.

BENEFITS: LED lighting consumes 50 percent less energy than traditional sources. It is four-times more energy efficient than regular light bulbs because more of the energy is converted into light than is lost as heat. There is no glass or filament, as in a light bulb, so LED tiles last forever. Also, the tiles are so rugged someone can jump on them without breaking them. LED lighting also covers the entire color spectrum of visible light so lighting can change from one color, or tone, to another with just one touch of a control panel.

If you would like more information, please contact:

Lighting Research Center
Rensselaer Polytechnic Institute
21 Union St.
Troy, NY 12180 USA
(518) 687-7100
http://www.lrc.rpi.edu
cimom@rpi.edu

FACTOID...

Thomas Edison developed the first commercial electric light bulb in 1879.

ON THE WEB:

Alliance for Solid-State Illumination Systems and Technologies: www.lrc.rpi/edu