As LED lighting is becoming increasingly
popular in architectural lighting, task lighting, medical lighting
(particularly for use in surgical theatres), transportation, entertainment, and
even household lighting. This article intends to be a comprehensive guide to
their utility, what the advantages that LED lighting possesses over other types
of lighting and how to select an appropriate power source for the LED bulb.
First, what IS an LED light? A
light-emitting diode (LED) is an electronic light source. LED's are based on
the semiconductor diode. When the diode is forward biased (switched on),
electrons are able to recombine with holes and energy is released in the form
of light. This effect is called electroluminescence and the color of the light
is determined by the energy gap of the semiconductor.
LED's present many advantages over
traditional light sources including lower energy consumption, longer lifetime,
improved robustness, smaller size ( enabling LED's to be easily populated onto
printed circuit boards.) and faster switching (LED's light up very quickly. A
typical red indicator LED will achieve full brightness in microseconds, and
LED's used in communications devices can have even faster response times.).
Thus their utility value is very high. Maybe the greatest advantage of all is
that as the color of the light depends on a specific variable (i.e.- the energy
gap of the semiconductor) thus LED's 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 for a vast range of
applications which previously used the colour filtering process.
Further advantages of LED's exist, among
them efficiency of an LED is prominent. LED's produce more light per watt than
incandescent bulbs, and wastage of energy is minimal, as LED's radiate very
little heat in the form of IR that can cause damage to sensitive objects or
fabrics. Wasted energy is dispersed as heat through the base of the LED.
Further as light is emitted from a solid state material, greater shock
absorption capability is present in the LED lights. Further, LED's do not
contain mercury, unlike most fluorescent lamps.
But LED's are currently more expensive, on
an initial capital cost basis, than most conventional lighting technologies,
and are very much sensitive to temperature and voltage. LED's must be supplied
with the voltage above the threshold and a current below the rating. This can
involve series resistors or current-regulated power supplies, and the proper
function of the power supply is an essential factor in creating maximum utility
and longevity of the systems. If too much current passes through the
semiconductor material forming the Diodes the LED will burn out! LED power
supplies must, among others, provide Universal AC input, allowing the full
range of applications, Short circuit, over load, over voltage protection, a
built-in dimming function, allowing the light levels to be adjusted to create
different effects.
And of course the safety of the LED power
supply is a prime concern, to prevent overheating, cooling should take place,
and the most efficient form of this is by free air convection. And the power
supply must come fully equipped with an isolated, (preferably) plastic case
that is resistant to external influences such as water on order to protect it
from harmful effects of water and dust.
If you are planning an LED lighting
project, for your home, garden or even your office or your shop, a thorough
research on the subject may be your best starting point. And as LED's are very
sensitive make sure you use an appropriate and high quality power supply. Speak
to your local electronic engineer or a reputed seller of LED lights and power
supplies for more information. A vast array of online LED and LED power supply
vendors exist as well. Their official websites offer high quality information
and specifications to tailor a solution for your lighting requirements.