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LED
Lighting - low power usage option
A
light-emitting diode (LED) is a semiconductor device that emits
incoherent narrow-spectrum light when electrically biased in the
forward direction. The color of the emitted light depends on the
chemical composition of the semiconducting material used, and
can be near-ultraviolet, visible or infrared. It consists of a
chip of semiconducting material doped with impurities to create
a structure called a p-n junction. Charge-carriers - electrons
and holes flow into the junction from electrodes with different
voltages. When an electron meets a hole, it falls into a lower
energy level, and releases energy in the form of a photon as it
does so.
LEDs
now are available in various colours such as red, infra red, green,
orange, yellow, emerald, blue, white, etc. Yellow LED lights are
a good choice to meet these special requirements because the human
eye is more sensitive to yellow light.
Unlike
incandescent light bulbs, which light up regardless of the electrical
polarity, LEDs will only light with positive electrical polarity.
If the voltage is of the wrong polarity, no light is emitted.
LED lighting only works on DC supply. On AC supply with change
in polarity it switches on and off. Thus LED lighting comes with
a DC converter circuit.
LED
lighting is a replacement for incandescent and fluorescent bulbs.
Solid State Lighting (SSL) is the application of LEDs in lighting.
Small spotlights made of many individual LEDs are used for lighting.
SSL LEDs are packaged as a cluster of white LEDs grouped together
to form a light source.
The
advantages of using LED lighting are that LEDs are capable of
emitting light of an intended color without the use of color filters.
Secondly the shape of the LED package allows light to be focused.
Incandescent and fluorescent sources often require an external
reflector to collect light and direct it in a useable manner.
LEDs are insensitive to vibration and shocks, unlike incandescent
and discharge sources. LEDs have an extremely long life span:
typically ten years, twice as long as the best fluorescent bulbs
and twenty times longer than the best incandescent bulbs. Further,
LEDs fail by dimming over time, rather than the abrupt burn-out
of incandescent bulbs. LEDs give off less heat than incandescent
light bulbs with similar light output. LEDs light up very quickly.
An LED will achieve full brightness in approximately 0.01 seconds,
10 times faster than an incandescent light bulb.
LED
lighting thus has a lot of advantages and looks to be the future
of lighting.
There
are many more appliance articles in our fixture
section. There is more specific information in the links at
the beginning of this article. They can guide you where you need
to go.
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