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What Is An LED?
The most
efficient light fixtures of the 21st century will be made from Light Emitting
Diodes, aka LEDs, small pieces of semiconductor that glow intensely when electricity
runs through them in the right direction. LEDs are the
light of the future.
LED is the acronym for Light Emitting Diode.
This is a tiny "solid state" semiconductor device much
like a transistor. An LED has the property that when an electrical
current flows between its conducting plates, almost all of the
power dissipated by the current flow over the voltage drop is
converted into visible light.
As a diode, the device will not permit current
to flow in the opposite direction, thus the electrical connections
must be of the correct polarity for the LED to function. With
special circuitry LEDs can operate with AC (alternating current),
emitting light the half-the-time when the polarity is correct.
Typically, over 85% of the energy of the electrical
current flowing through an LED lamp is converted into visible
light. Very little of the energy is used to create heat. However,
if a resistor must be used in series with the LED to reduce the
DC voltage to match that required by the LED, the voltage drop
across the resistor will create heat that must be dissipated.
The average lifetime of an LED that has been
burned in (operated past the time when "infant mortalities"
occur) is typically 100,000 hours of continuous operation. That
amounts to over 11 years. Shocking an LED with over-voltage or
with excess heat will lower the lifetime of the device.
Since the LED is a solid state device, if
it is securely mounted, it is quite resistant to physical damage.
The color of the light created by an LED is
determined by the chemical composition of the semiconducting
material. The most common LEDs available today produce light
that is ultraviolet (400nm: a wavelength of 400 nanometers),
pink (420nm), blue (470nm), aqua (505 nanometers), green (525nm),
yellow (590nm), red (605-660nm), and infrared (880-945nm). Prices
of LEDs depend upon their color; for example, pink is more than
twice as expensive as red.
Energy Distribution for a Blue
LED
The spectrum of colored LEDs is very sharp.
An LED resonates at a single optical wavelength, and produces
one and only one color. As you can see in the figure above, there
is no light energy produced in the other wavelengths. If you
look at a red, green, or yellow LED through a blue filter (which
blots out all light except blue), you will see no light coming
through the filter.
What we recognize as white light is a "spread
spectrum," energy in wavelengths ranging from ultraviolet
to infrared. White light has a mix of all colors in it. LEDs
that produce white light are hybrids: the light from an ultraviolet
or blue LED shines through a special phosphorescent material
that absorbs much of that light energy and re-emits it at a lower
energy to produce a spread white spectrum. However, you will
still see a peak of light energy at the wavelength of the exciting
LED.
Energy Distribution for a White
LED
Though the light from white LEDs appears bluish,
it is suitable for much of the lighting in RVs. As improvements
are made in the phosphorescent materials, white LEDs will become
"warmer," meaning less of the excitation color will
come through and more of the longer wavelength colors will be
mixed in.
White LEDs are not recommended for use as
vehicle brake and turn-signal lights. There is little energy
in the spectrum between 600nm and 700nm, the colors that can
be seen through the red lens covers. Use the native red-colored
LEDs instead.
LEDs have been in use for over twenty years,
and the technology has improved over that time. However, up to
now the suitability of LEDs for interior RV lighting has been
inadequate. Though the prices have been pushed low, the quality
and applicability of the existing products has been marginal
at best.
Recent advances in technology have changed
that picture. LightBlasters uses the latest nexLED™
LED technology to design intense, high-performance devices for
RV lighting applications. This new technology, coupled with strict
attention to product quality and applicability, are key to providing
the Prudent RVer with adequate LED lighting for their RV. |