Saturday, July 20, 2013

Use of LED Lamps for Lighting

Today LED lamps are increasingly being used for lighting purposes. It has much better qualities as a light source than the conventional incandescent bulbs or CFL lamps. LED lamps are made out of light emitting diodes or LEDs that are arranged into assemblies of high power light that can be focused to a single direction. LEDs consist of small capsules or lenses in which a tiny solid state chips are placed on a heat conducting material. The luminescence of a single LED is improved by arrangement of multiple LEDs that gives more light.  LED lamps have greater luminous efficacy and they produce more light per unit of electrical power. LED lights are able to emit 100 lumens of light per 1 watt of power and the efficacy continues to improve with the latest LED chips. The light conversion efficacy is more compared to the incandescent and fluorescent lamps. With the use of high efficiency reflector, high transmitive diffuser, and high power LEDs, there is considerable saving in energy and improving efficiency.

The Working Principle of LEDs
LED or a light-emitting diode is a semiconductor diode light source that emits light. It is used as a lighting source as an indicator lamp. When a diode is switched to the 'on' position or forward biased, the electrons in the LED recombine with holes releasing energy in the form of photons or light. This effect displayed by the LED is called as an electroluminescence. Many different colors are also produced by the LEDs other than white light. The wavelength and the color emitted depends on the materials forming the p-n junction. Because of the smaller size of LEDs, integrated optical components are introduced inside, which are used to shape the light produced from it.


Applications
LED lamps can be replaced with ordinary incandescent or fluorescent lamps to provide good lighting in homes, automobiles, public facilities, stores, godowns etc. LEDs are more commonly used in aviation lighting, automotive lighting, displays, advertising, general lighting, and traffic signals.


Advantages
LEDs have very smaller energy consumption and it is environmentally friendly.
LED lamp provides long hours of service and so less replacement.
LEDs are more robust and smaller in size.
LED lamp has high energy efficiency and saves energy and reduce the electricity bills.
The light from the LED lamps are more sharper and are very direct.
LED lamps are very flexible and adaptable to suit the convenience of the place.
LED lamps provide wide choices in lighting and colors to and has a large number of effects, moods, and ambiances for the room.
LED lamps provide a uniform level of illumination and the lighting is more comfortable to work and less glare and strain to the eyes.
LED lamps has a great variety of designs and shapes for each room, place, and settings.
LEDs contain no contaminants and so lesser pollution to the environment.
LED lamps have over 40,000 burning hours and hence it is maintenance free.
Installation of LED lamps are easy because of the compact size and adaptable designs.

Disadvantages
The cost of LED lamps are slightly higher than that of fluorescent or incandescent lamps and so the initial cost may be higher.
LED lamps use direct electric current and so it needs rectification, filtration, and regulation when connecting it from AC, for its smooth functioning.
Optimum voltage and current is needed for LEDs to function normally.
LED are degraded or damaged by high operating temperatures, and so heat dissipation elements are needed such as heat sinks or cooling fins.

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