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General Intro
LED is the acronym for "Light Emitting Diode". LED technology is based on
the electroluminescence generated by the emission of photons. Unlike
common light bulbs whose fi laments work at very high temperatures
and feature a remarkable thermal inertia, an LED emits cold light. The
LEDs that we are interested in are those that emit red, orange, yellow, or
green light. In relatively recent times the creation of a blue LED was also
achieved. This development is very important as a blue LED combined
with green and red radiations allows the creation of a white light sour-
ce and also of all those colours allowed by an RGB (additive synthesis)
combination. In recent years LED technology has been the choice in all
applications requiring high reliability, long life span and top effi ciency.
Some of its main applications are:
•
Decoration and signage
•
Variable message LED Walls
•
Entertainment and architectural lighting
LED technology is employed more and more in architectural and enter-
tainment lighting instead of more traditional light sources, but its low
power prevents it from replacing them completely. Basically, its main
drawback is the amount of emitted light (fl ux of light expressed in lu-
mens) which ranges up to 120 lm for the most recent professional mo-
dels, whereas a 60W incandescence light bulb emits a light fl ux of about
550 lumens.
The advantages in the use of LED technology for lighting are:
•
Long life span (high emission LED can last up to 50,000 hours)
•
No maintenance costs
•
High performance (if compared to incandescent light bulbs or
halogen lights)
•
Non polluting, as it does not include IR or UV components
•
Sharp spot eff ect (highly specifi c point source)
•
Safety, as it works with very low voltage (normally around 24 Vdc)
•
No sensitivity to humidity or vibrations
•
No mercury
Finally, the commercial strength of such equipment lies in its brightness
(four times brighter than fl uorescent lights and tungsten fi lament lights),
low price, high effi ciency and reliability. Furthermore, an LED can last a
lot longer than any classic light source (especially if under mechanical
stress) and its very low absorption allows it to be used anywhere.
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