LEDs are solid state semiconductor devices. LED illumination is achieved when a semiconductor crystal is excited so that it directly produces visible light in a desired wavelength range (color). LED units are small, typically 5mm .
The color composition of the light being emitted by the LED is based on the chemical composition of the material being excited. LEDs are available that can produce colors including white, deep blue, blue, green, yellow, amber, orange, red, bright red and deep red.
The utilization of indium gallium nitride (InGaN) as a semiconductor material resulted in the brightest LEDs and enabled the development of the white light LED.
White light LEDs feature a phosphor added to a blue LED that converts some of the light emission into yellow, resulting in a bluish-white light. White light LEDs are therefore a cool light source with a spectrum of correlated color temperatures of 4,000-11,000K. Color rendering is considered poor. White light can also be achieved by color mixing the light produced by red, blue and green LEDs. The production of visible white light offers the promise that LEDs can be used in general lighting applications. As the light output and color rendering capabilities of LEDs improve, many more architectural applications will open up for this source.
Several manufacturers currently offer a range of LED fixtures for replacing MR16 lamps, display lighting, cove lighting, underwater lighting, architectural details and other applications. Come manufacturers are using colored LED arrays in these applications, combining red, blue and green LEDs to produce millions of colors, including white light. Designers should carefully consider requisite lumen packages, source brightness, viewing angles and color rendering when considering use of this technology.
