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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.
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