is an LED?
diodes (LEDs) are electronic components that produce light without
heat or the use of high voltages.
of the LED
known report of a light-emitting solid-state diode was made
in 1907 by the British experimenter H. J. Round. However, no
practical use was made of the discovery for several decades.
LEDs became commercially available in the 1970s, and were almost
all red. They were commonly used as replacements for incandescent
indicators, and in seven-segment displays, first in expensive
equipment such as laboratory and electronics test equipment,
then later in such appliances as TVs, radios, telephones, calculators,
and even watches. These red LEDs were bright enough only for
use as indicators, as the light output was not enough to illuminate
an area. Later, other colors became widely available and also
appeared in appliances and equipment. As the LED chemistry became
more advanced, the light output was increased, and LEDs became
bright enough to be used for illumination.
of using LEDs
- LEDs produce
more light per watt than do incandescent bulbs; this is useful
in battery powered or energy-saving devices.
- LEDs can
emit light of an intended color without the use of color filters
that traditional lighting methods require. This is more efficient
and can lower initial costs.
- The solid
package of an LED can be designed to focus its light. Incandescent
and fluorescent sources often require an external reflector
to collect light and direct it in a usable manner.
- When used
in applications where dimming is required, LEDs do not change
their color tint as the current passing through them is lowered,
unlike incandescent lamps, which turn yellow.
- LEDs are
ideal for use in applications that are subject to frequent on-off
cycling, unlike fluorescent lamps that burn out more quickly
when cycled frequently.
being solid state components, are difficult to damage with external
shock. Fluorescent and incandescent bulbs are easily broken
if dropped on the ground.
- LEDs have
an extremely long life span. One manufacturer has calculated
the ETTF (Estimated Time To Failure) for their LED’s to
be between 100,000 and 1,000,000 hours . Fluorescent tubes
typically are rated at about 10,000 hours, and incandescent
light bulbs at 1,000-2,000 hours.
- LEDs mostly
fail by dimming over time, rather than the abrupt burn-out of
- LEDs light
up very quickly. A typical red indicator LED will achieve full
brightness in microseconds; LEDs used in communications devices
can have even faster response times.
- LEDs can
be very small and are easily populated onto printed circuit
- LED requires
much less power to output the same amount of light as a similar
- An LED
light bulb can last you up to 60,000 hours. That averages out
to 12 hours of light per day for 12 years.
- LED light
bulbs are so energy efficient that, depending on how often you
have them on, they'll actually pay for themselves in just over
- The best
way to conserve energy is to use less of it. LED light bulbs
are directional - which means that they only put the light where
you aim it or where you need it. Incandescent bulbs, on the
other hand, just sit there and throw their glow all over the
place - wasting electricity and generating heat.
- LED light
bulbs run cool, so they're safer to use than fragile, burning
hot halogen and incandescent bulbs.
- LEDs turn
on instantly - which has been a big benefit in car brake lights
and is also a welcome feature when testing lights in a dark
- LEDs do
not use mercury like CFLs - so disposal concerns aren't the
of LED applications
can be used in Cove lighting, decks, windows and Under Bar lighting
- Used in
progressive signs like in Casinos over a bank of Slot Machines
in a ‘chase sequence’
- Use an
LED light bulb in a task or reading light, and you'll have a
bright, white light to work by. LEDs not only produce light
more efficiently, they have a tiny mirror that reflects light
in one direction. A directed light means less wasted light.
- LED light
bulbs cost just pennies a day to run, so they are perfect for
those always-on or accidentally-left-on lights like on porches.
indicators on all sorts of equipment
lights and signals
- Exit signs
and Bicycle lights
- Toys and
recreational sporting goods, such as the Flashflight
Some models that do not even use batteries are of this type.
- Light bars
on emergency vehicles.
Push Button Lighting