Saturday

A Brief History Of The LED

The Light Emitting Diode, or LED to it's friends, is a staple of modern electronics and is making inroads into the area of lighting, both commercially and in homes. In effect, it's a solid-state version of the incandescent light bulb, and it's been around commercially for 50 years now. You can get an explanation of how LEDs work here, and as with many inventions there was more than one person involved, and it happened over a long period of time.


LED


The incandescent lamp was made practical by Thomas Edison in the late 1800's, although work had also been done by Joseph Swan in the UK around the same time. The traditional light bulb produces light (and heat) by passing an electric current through a thin metal wire filament until it glows white hot - but without melting away (at least for a while).


light bulb


The LED produces light by electroluminescence, a phenomenon discovered independently by Oleg Losev and H.J Round  in  1907. In the early 1960's an infrared LED was accidentally discovered by Gary Pittman and Bob Biard at Texas Instruments during an attempt to make a laser diode. This was followed soon after by the first red (visible light) LED by Nick Holonyack Jr at General Electric in 1962 - 50 years ago. Subsequent experimentation in the 1970's by others on different materials begat LEDs of different colors - yellow, blue, etc.


The diode itself does not have much to do with light output, it's an electronic component that can act as a "one way switch" - it lets current flow in one direction, but not in the other - which can be a very useful effect in many types of circuits. Diodes were the first semiconductor electronic devices. The "light emitting" part is explained here.

1 comment :

jam martine said...

LED lights have been using to overcome the problem of incandescent lights. LED lights use diodes to produce light so they do not produce too much heat as incandescent lights. They are cost effective and energy efficient also.
Reference: http://www.adattsi.com/induction-lighting/high-bay