LED stands for light-emitting diode. Basically, it is a semiconductor light source that emits light by solid-state electroluminescence, as opposed to thermal radiation from incandescent light bulbs, or the fluorescent light from devices of that name. The first practical LED light was developed in 1962 by Dr. Nick Holonyak, while working at the General Electric Company. In 1963, Dr. Holonyak wrote an article in the Readers Digest, predicting that LED lights would one day replace incandescent light bulbs in lighting. Later, while a professor at the University of Illinois, Urbana-Champaign, he would train other doctoral candidates who would go on to work in the field of LED lighting for companies like Philips Lighting Company (now a maker of Philips LED bulbs).
The first LED lights were expensive to make and limited in use. Throughout the 1960’s improvements were made to manufacturing techniques and materials, and LED lights improved, while costs came down. First uses were limited to indicator lights and small displays on electronics devices, but as materials and technology matured, the quality of the light output and uses grew. The first LED lights were colored; first red, then other colors were developed. Eventually, it was found that by combining yellow with blue, the output changed to bright white-colored light. Technology advances in 2008 and 2009 improved the quality of visible LED light and lowered production costs.
One of the companies advancing the technology of LED lighting is Cree, Inc. Established in 1987, Cree is a multinational maker of semiconductor materials and devices. Cree LED lighting has been at the forefront of this technology, making major strides in the areas of efficiency and lumens per watt of power used. Not only does Cree manufacture LED light bulbs, but Cree components are often used by other LED lighting manufacturers in their products.
What goes Into a LED light bulb? LED light bulbs come in an amazing array of shapes and sizes. Socket sizes range from standard A-series (regular light-bulbs), to the decorative E-series, to the candelabra C-series, to PAR-series spotlights. In simplified terms, an LED light bulb consists of a series of LED chips arrayed on silicon submounts and connected to a cathode lead. These are arranged on a housing containing a heat sink and other components, and covered with a plastic lens (no thin breakable glass is used in LED light bulbs). The plastic lenses of LED light bulb are very durable and will not shatter like glass bulbs a bulb is dropped. Some LED light bulbs have reflective flanges to help evenly radiate the light in all directions. One model even has an internal cooling fan. Overall, LED lights are an advancing technology that improve lighting efficiency while reducing power consumption by copious amounts.