LEDs are solid state light sources comprised of an integrated circuit using semiconductor technology. Historically, they have been used in electronic devices as red indicator lights on electronic interfaces. Advances in the early 1990s inspired researchers to pursue the dream of developing white solid state general lighting solutions. Modern LEDs now come in a variety of shapes, sizes and colors, often relying on phosphor powders to produce very specific colors.
LED lights are highly efficient, using less energy and generating less heat than traditional incandescent or fluorescent bulbs, while yielding excellent brightness and light quality. Typical lifetimes for solid state lights are 25,000 - 100,000 hours, compared to 1,200 - 20,000 hours for compact fluorescent lamps (CFLs) and around 1,000 hours for AC incandescent lamps.
A semiconducting material is one that can transport an electric current, and has an electrical conductivity between that of a conductor and an insulator. Devices made from semiconductor materials are the foundation of modern electronics, including computers and telephones. Examples of semiconductor devices include tiny light-emitting diodes (LEDs), wherein the semiconductor is the die chip, and solar photovoltaic panels.
Phosphors are materials that absorb light and convert it into a broad range of other lower energy wavelengths of light. For example, Intematix phosphors are coated over blue LED chips, and, depending on the precisely controlled color selected by Intematix's proprietary family of phosphor materials, consistent, high quality white light of varying color temperatures and CRIs shines out of the device.
Wavelength is another way to describe the color of light along the complete electromagnetic spectrum. Human eyes can see only a limited slice of the full electromagnetic spectrum, and this "visible light" ranges in wavelengths between 400 - 700 nanometers (nm). The visible colors from shortest to longest wavelength are: violet, blue, green, yellow, orange, and red.
CRI is a measurement that was originally created to help indicate how colors appear under different light sources. The closer the CRI is to 100, the better the artificial light source reproduces the colors of objects faithfully in comparison to the sun on a beautiful day. Despite its limitations, CRI is the only internationally agreed upon color rendering system. New measurement standards are in development to address some of the concerns about using CRI.
The CCT of a light source is the temperature at which an ideal black-body radiator gives off light. The temperature is reported in units of Kelvins, with higher color temperatures such as 5,000K corresponding to cooler (bluish) colors, while lower color temperatures such as 2,700K correspond to warm (reddish) colors.
A lumen is a unit of measure of the power of light perceived by the human eye. It is the unit to look for when measuring the differences in available light between two distinct light sources.
Watts are a unit of measure that describe how much power a device requires to function. For example, a typical incandescent bulb might consume 100 Ws. A typical LED, on the other hand, might only require 20W to give off the same amount of lumens.
A quantitative measure of performance from light sources, calculated as lumens (lm) per watt (W). The higher the luminous efficacy, the better the energy efficiency of the light source. An incandescent light bulb might have a luminous efficacy of 14 lm/W while LEDs have been demonstrated to have efficacies as high as 200 lm/W in research labs.
Cold Cathode Fluorescent Lamps (CCFLs) are sealed glass tubes filled with inert gases, such as a neon lamp. When a high voltage is placed across the tube, the gases separate into ions creating ultraviolet (UV) light. Visible light is created when the UV light excites a lining of phosphor within the tube.
© 2010 Intematix. All rights reserved.
