Light-Emitting Diode

A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting. Introduced as a practical electronic component in 1962, early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness.

When a light-emitting diode is forward-biased (switched on), electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. LEDs are often small in area (less than 1 mm2), and integrated optical components may be used to shape its radiation pattern. LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved robustness, smaller size, and faster switching. LEDs powerful enough for room lighting are relatively expensive and require more precise current and heat management than compact fluorescent lamp sources of comparable output.

Light-emitting diodes are used in applications as diverse as replacements for aviation lighting, automotive lighting (in particular brake lamps, turn signals, and indicators) as well as in traffic signals. LEDs have allowed new text, video displays, and sensors to be developed, while their high switching rates are also useful in advanced communications technology. Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players, and other domestic appliances.

How different light source works?

Fluorescent
A fluorescent lamp or fluorescent tube is a gas discharge lamp that uses electricity to stimulate mercury vapor. The stimulated mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp changes electrical power into light more efficiently than an incandescent lamp.

Incandescent
The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric light that works by incandescence. An electric current passes through a thin electrical filament, heating it to a temperature that produces light. The enclosing glass bulb contains either a vacuum or an inert gas to prevent oxidation of the hot filament.

Halogen
A halogen lamp is an incandescent lamp with a tungsten filament contained within an inert gas and a small amount of a halogen such as iodine or bromine. The combination of the halogen gas and the tungsten filament produces a chemical reaction known as a halogen cycle.

LED
LED lighting products work much like standard lights, except for the fact that LED lights are much smaller and contain no filament and harmful gases. Instead of a filament and gas, an LED creates light using nothing but the movement of electricity along the path of its semiconductor. As the electrons stream across the semiconductor, they create electromagnetic radiation. Some forms of this electromagnetic radiation can take the form of visible light. There are no harmful gases such as mercury used in the production of LED lights, as opposed to the toxic levels that are used in all the other different light sources.

What are the Harmfull Effects?

Mercury
Mercury vapor can cause effects in the central and peripheral nervous systems, lungs, kidneys, skin and eyes. It is also a mutagenic and affects the immune system. Acute exposure to high concentrations of mercury vapor causes severe respiratory damage, while chronic exposure to lower levels is associated with central nervous system damage. Chronic exposure to mercury is also associated with behavioral changes and alterations in the nervous system.

UV Radiation
UV radiation causes the aging process of some plastics used in the construction of luminaries to be accelerated, leaving them significantly discolored after only a few years of service. Polycarbonate suffers particularly from this problem, and it is not uncommon to see fairly new polycarbonate surfaces positioned near the lamp to have turned a dull, 'ear-wax'-like color after only a short time. It is important to note that if the polycarbonate is being damaged what is the UV radiation doing to people that are under these lights all day and night? It has been suggested that the effects have caused tumors in lab animals.

LED
With all fluorescent, sodium, halogen and metal halide lamps containing mercury and other harmful metals and gases it is important to note the effects of exposure to the mercury vapor. We know that LED lighting products are a safe alternative to mercury lights and UV radiation from lights.

End of life & waste

Fluorescent - Incandescent - Halogen
When discarding a fluorescent tube, the main concern is the mercury, which is a dangerous pollutant.

Mercury vapor lamps rarely burn out completely and suffer drastically from lumen depreciation. The lamp produces 50% less light every five years, to the point of becoming ineffective while still drawing the same amount of power it drew when it was new. This happens because the emitter is deposited as a film, darkening the arc tube wall and reducing light output.

A broken fluorescent tube will release its mercury content into the atmosphere, and be inhaled by others. Safe cleanup of broken fluorescent bulbs differs from cleanup of conventional broken glass or incandescent bulbs, 99% of the mercury is typically contained in the phosphor, especially on lamps that are near their end of life.

The disposal of phosphor and particularly the toxic mercury in the tubes is an environmental issue. Governmental regulations in many areas require special disposal of fluorescent lamps separate from general and household wastes.

LED
By changing to energy efficient lighting with LED lighting products, you save financially in the short and long term, plus, you are assisting the environment by not adding harmful gases into the atmosphere and not adding to our waste deposits. You also save on the maintenance that is required for conventional mercury light sources from a qualified electrician.

Applications & Benefits of LED

Lighting type comparison table

Type	Incandescent	CFL	LED
Efficiency	10 ~ 15 lm/w	40 ~ 90 lm/w	60 ~ 120 lm/w
Life	1000 ~ 2000 hrs	4000 ~ 5000 hrs	40000 ~ 50000 hrs
Mercury	NO	YES	NO
UV	NO	YES	NO
Prohibition	2012	within 10 years	n/a
Heat	Highest	Medium	Controlled
Best Option	3	2	1