Once limited to simple status indicators, Light Emitting Diodes (LEDs) now play prominent
roles in back lighting, panel indication, decorative illumination, emergency lighting, animated
signage, etc.... The emergence of LEDs as a viable alternative to incandescent lighting can be
attributed to new manufacturing technologies, packaging innovations and an increasing
number of colors. These factors along with the growing awareness of the advantages of LEDs
(e.g., a life span measured in years not hours, vivid sunlight-visible colors and low power
requirements) have engineers, product designers, purchasing agents and component vendors
viewing LEDs in a whole new light.
For many applications LED lamps are superior to incandescent lighting. So why is it that in
tens of millions of switches, indicators, control panels, signs, annunciators, displays, decor
lights and dozens of other applications, design engineers still specify incandescent
technology? It might be that they’re just a few years behind what’s really happening in LED
illumination.
Although advances made in LED technology in the past few years have dramatically
broadened the applications for these rugged little light sources, it wasn’t that long ago that red
was the only “daylight-visible” colored LED. And that wasn’t the only thing limiting their use!
Unlike incandescent bulbs that give off the full spectrum of light in a spherical pattern, LEDs
emit a focused beam of a single wavelength (color) in only one direction, in a variety of angles.
For many applications, such as indicators or switch illuminators, this is not a problem, but it
took the development of multi-chip arrays and high-flux LED chips to begin to achieve the
effect of an incandescent filament.
Major advancements in LED technology have taken place in recent years such as
development of new “doping” technologies that increase LED light output by as much as 20
times over earlier generations, and allow the production of daylight-visible LEDs in virtually any
color of the spectrum. In addition to red, yellow, and amber/orange, LEDs are now available in
many colors from leaf green to ultra blue. Even white light, long thought to be an impossibility,
is now available in three different shades as a light-emitting diode.
The efficiency of LEDs is most apparent in applications requiring color. Light from a typical
incandescent bulb must be filtered so that only light from a particular part of the spectrum
(e.g., red, amber or green, etc...) for example—is visible. While LEDs deliver 100 percent of
their energy as colored light, incandescent bulbs waste 90 percent or more of their energy in
light blocked by the colored lens or filter. Incandescent bulbs also waste 80 percent to 90
percent of their energy on heat generation to reach the temperature for which (Kelvin scale)
they are designed.
The point is that what was once a fairly marginal light source isn’t marginal any more. In many
applications, LEDs exceed the energy available from incandescent bulbs and offer significant
additional benefits making LED clusters and lamps as friendly to the environment as they are
to the operating budget.
LEDTRONICS [ LEDTRONICS, INC ]
