A light emitting device, for example, a light emitting diode is a type of semiconductor device that can convert an electric energy into a light has been spotlighted as next generation light source, replacing a conventional fluorescent lamp and an incandescent lamp.
The light emitting diode generating a light by using a semiconductor element may consume relatively small electricity, compared with the incandescent lamp generating a light by heating tungsten or the fluorescent lamp generating by colliding an ultraviolet ray generated by a high voltage discharge with a phosphor.
In addition, the light emitting diode generates the light by using a potential difference of semiconductor elements may have a relatively long usage life and a rapid response, with an eco-friendly characteristic.
As a result, a lot of developments and researches have been in progress to replace the conventional lighting source with the light emitting diode. Usage of such the light emitting diode has been increasing as lighting source for a lighting device, for example, a variety of lamps, a liquid crystal display and an electronic display and streetlamp that are used outdoor.