LED Lighting Information

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Fast History- Electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round using a crystal of silicon carbide and a cat’s-whisker detector. A Russian and a handful of Americans made further developments. In 1962, Nick Holonyak Jr., while working at General Electric Company invented the first yellow LED and improved the brightness of red and red-orange LEDs by ten fold. But it was still expensive. It wasn’t until the 1990's that big companies got behind the technology and started making substantial progress. Companies like Nichia, Cree, Philips, and Seoul have made vast improvements. Using nano-crystals, the luminous intensity has reached levels of 300 lumens per watt. (A standard 60 watt light bulb can produce about 15 lumens per watt.)

What (the heck) is a Light Emitting Diode (LED) ? -

These guys do a pretty good job of explaining the general concepts:

http://www.lrc.rpi.edu/programs/nlpip/lightinganswers/led/indicationIllumination.asp

To elaborate on the formation of colors, many LEDs start off as a “blue” color and have various compounds added to them. This is sometimes called “doping” an LED.

Maybe you’re familiar with these types of LEDs- DIP, SMD , or an LED array (single-chip multi-pack)

*For lighting definitions, please see below*

Color Temperature: a temperature defined in terms of the temperature of a black body at which it emits light of a specified spectral distribution: used to specify the color of a light source. It is usually measured in degrees Kelvin (K). The human eye can see colors between infrared and ultraviolet. Below are some of the more common color temperatures used in LED lighting.

When it comes to LEDs, there are a lot of choices out there! It is easy to shop online, pay, and then be disappointed with the performance or quality of the product.

ALTRUEN brings you the best balance of quality and economy. You will not be disappointed with our products. Among ALTRUEN’s clients are refrigerated ocean-going freighters that forge through the unforgiving waters of the Bering Sea and Western Alaska, putting our lights to the test. They come back again and again, and refer us to other businesses.

Quick Tips in Buying Quality LEDs:

1. You usually get what you pay for.

2. Heat Sink- Unit should not become uncomfortably hot, good thermal management is the key to longevity, item should be relatively heavy (starting at about 5 watts and above).

3. Certifications and Listings: Verify the UL number belongs to a reputable company.

4. Warranty- Is it 1 year? 3 years? Make sure you get what you pay for.

5. Ask for the LM-79 testing information: most serious companies have this testing done for their products, especially if it is used for safety.

General Lighting Definitions: as defined by archlighting.com/industry-news.asp?articleId=1184195

Spectral power distribution: The output of a light source, characterized by its relative strength at each wavelength.

Spectral reflectance distribution: The response of an object to light, characterized by the wavelengths that it primarily reflects.

CIE chromaticity diagram: The visual spectrum bent to form a more or less triangular plane on which any color may be assigned an X/Y value. It provides a means by which color differences between sources or objects can be qualified, or by which color shifts of a single object when illuminated by different light sources can be qualified.

Correlated color temperature: The absolute temperature of a black body whose chromaticity most nearly resembles that of the light source being measured.

Black body radiator: A temperature radiator of uniform temperature whose radiant exitance (total light leaving an area) in all parts of the spectrum is the maximum obtainable from another temperature radiator at the same temperature.

Munsell color system: A system of surface-color specification based on perceptually uniform color scales of the three color variables: hue, value, and chroma.

Color rendering index: A measure of the degree of color shift that objects undergo when illuminated by the light source as compared with those same objects when [ illuminated by a reference source of comparable color temperature.