Light Emitting Diode

LEDs have an incredibly long life, lasting between 50,000 to 100,000 hours, compared with normal light bulbs lasting about 1,000 hours and fluorescent tubes lasting 7,500 hours.
LEDs have two catagories that use inorganic light emitting materials and those using organic light emitting materials. The former are known simply as LEDs, while those using organic materials are known as OLEDs (Organic LEDs).
In the first LEDs to become commercially available, the semiconductor was made from a combination of three elements: gallium, arsenic and phosphorus (GaAsP). They produced a red light and appeared in the early 1960s. Advances in epitaxial crystal growth processes resulted in the use of new compounds - such as indium gallium aluminium Nitride - enabling a bright blue LED to be developed.

The basic LED consists of a semiconductor diode chip mounted in the reflector cup of a lead frame that is connected to electrical (wire bond) wires, then encased in a solid epoxy lens.
LEDs emit light when energy levels change in the semiconductor diode. This shift in energy generates photons, some of which are emitted as light. The specific wavelength of the light depends on the difference in energy levels as well as the type of semiconductor material.
LEDs are highly efficient because most of the energy they produce radiates within the visible spectrum. About 30% of the light generated inside the chip makes it's way out of the brightest LEDs. By one estimate, the potential energy-savings from replacing the incandescent traffic signals in the USA alone with LED signals would save nearly 2.5 billion kilowatt hours annually. Up to now, may countries including China, America, Australia and European countries have uesed LED instead of traditional lighting.

History and Prospect of LED
LED (Light-Emitting-Diode) is a semiconductor changing electrical power into visible light.
In 1923, a German scientist insert the probe in carborundum used as a radio detector, and observed the lighting phenomenon when the direct currect was on.
In 1962, the red LED made of CaASP was invented.
In 1969, the green LED made of Gap+N was invented.
In 1993, the blue LED was invented.
In 1996, the white LED¡¯s invention in Japan brought the new lighting stage for LED.
In 2000, LED was used in indoor lighting.
In 2010, the LED lighting will occupy 20% illumination market in the world.

Specialty of LED
Saving Power: high effect lighting, lowest power consumption, the wattage of single LED lamp is from 0.06w to 1w.
Long life: When luminous flux attenuates to 70%, single LED lamp’s nominal life is 100,000 hours.
Extensive application: small volume, easily be shaped into exquisite and applied products in pattern of point, line or plane.
Multiform controlling: can adjust the lighting by changing the current. The dynamic colorful changing can be realized by digital controlling.
Splendid colors: narrow spectrum, pure color, nice vision, as lamp house, the single color feature can be well used.
Environmental protection: no injurant in material, the castoff can be recycled and no pollution.