About LEDs PDF Print E-mail
The need for an illumination device with low power requirement led to the utilization of solid-state lighting. Solid-State Lighting is used to refer to lighting applications that use Light Emitting Diodes (LEDs).

LEDs are really a fancy diode, with the unique “side effect” of producing light when electricity flows through them. LEDs are different from ordinary light bulbs because they do not have a filament to break or burn out. They operate on very low voltage, generate very little heat, and are ideal for putting lights into portable equipment and self-contained solar lighting devices.

In the simplest terms, an LED is made with two different kinds of semiconductor material: one type that has too many free electrons roaming around inside, and another that doesn't have enough. When an electron from one material (the donor) gets pushed across a thin barrier and gets into tiny spaces in the other (the holes), a photon or particle of light is produced.

The color of light depends on a number of factors, including the type of material they make the LED with and the material's quantum bandgap (how much energy each electron needs to pack in order to cross the barrier).
A smaller bandgap that fairly weak electrons can cross gives you infrared or red light, while a large bandgap that needs really strong electrons gives you light that has a blue or violet color to it.
The light intensity or output of a system using LEDs is a function of the number of LEDs used, and is basically proportional to it. More LEDs give more light.

LED lighting systems are not only a power-saving alternative to conventional lighting systems, but they are also viewed as a possible solution on both macro and micro levels to numerous problems related to conventional lighting systems.

As a power-saving alternative to conventional lighting systems, LED lighting systems offer a viable substitute through providing equivalent lighting yet utilizing 50-80% less energy for its operation, saving electrical costs. LED Lighting Systems are also maintenance free and long lasting, as they contain no filament or gas, they outlive conventional lighting systems by up to 5 times.

LED Lighting Systems can also be viewed to be a solution partly or in full to a number of problems common to conventional systems:
  • Energy Problem: as LEDs consume 50-80% less power for the same lighting intensity as traditional light bulbs, LED offers massive power saving in electrical energy, reducing electricity bills, and power consumption.
  • Power Instability Problem: LEDs are less affected by power instability such as voltage and current irregularities and variations, although extreme variations affect their light output, such power fluctuations do not cause LEDs to malfunction or break down.
  • Heat Generation Problem: with traditional light bulbs, incandescent light bulbs in specific, most of the electrical power supplied to energize the light bulb is transformed into heat emitted by the bulb. LED lighting produces virtually no heat, and thus contributes to minimizing global warming problem. The almost non-existent heat emission of LEDs reduces cooling requirement in hot indoor areas, and thus contributes to power saving in cooling as well as a consequence.
  • Environmentally Friendly: unlike Mercury Bulbs and similar gas discharge lighting systems, LED lighting contains no environmentally hazardous chemicals or materials, and does not shatter or break, thus contributing to a cleaner environment with no harmful emissions.
  • Visibility & White Light: LEDs emit white light (warm and pure white), which is proven to enhance visibility of the human eye, resulting in better illumination of areas and higher visibility, with no glare, in comparison, Sodium Bulbs produce dim Orange light with high glare, which reduces visibility and reflects objects in different colors.
  • Instant-On: LED lights produce full light on instantly when switched on unlike Gas Discharge Bulbs which require an “ignition” period until they reach full lighting capacity.
  • Ultra-Violet Light: LEDs do not produce Ultra-Violet light as in Mercury Bulbs and Fluorescent lights which attract insects.
  • Temperature Variation Effect: LEDs are not affected with variation in ambient temperatures, which is a negative aspect of traditional Gas Discharge lights, as variation in temperature affects their lighting performance.