Led operating principle The LED term is: the acronym of Light Emitting Diode, literally light-emitting diode. The diode is a semiconductor electronic component, with capacit & agrave; of intermediate electrical conduction between a conductor and an insulator, whose characteristic function is that of allowing the flow of electric current in one direction and almost totally blocking it in the other. The Led therefore is; a particular diode that exploits the characteristics of specific materials that emit light in the form of photons at the passage of the electric current. LED's main applications beyond lighting are mobile electronics and signage. Most LEDs do not emit light in all directions, so their directional characteristics obviously influence the design of lighting systems, but omnidirectional LED lamps that radiate light over an angle of 360 °. they are becoming more and more; common. p>
The light emission of the single Led is; lower than that of a compact incandescent or fluorescent bulb, so to increase the luminosity, which is measured in lumens, the Led lamps use many contiguous and high power diodes, or Led modules, which are groups of one or more ; light emitting diodes, mounted on a printed circuit. The main producers of LEDs for lighting come from the semiconductor industry and are mainly concentrated in Japan, the United States and Korea. & nbsp; Birth and evolution of LEDs The first LEDs were studied and developed during the '60s, but they were very low power and emitted only light at low frequency, that is in the spectrum of red. p>
The first high power blue LED light, designed and built in 1994 by Shuji Nakamura, a researcher at Nichia Corporation, was a key event for the development of the first light LEDs white, which generally needs lighting. Shuji Nakamura, the first designer of blue light LEDs, and researchers Isamu Akasaki and Hiroshi Amano, were awarded the Nobel Prize in Physics in 2014. To convert cold and blue light, not ideal for the eye, into white light with a number of possible variations, it is thought of experimenting with the use of a series of substances to the point of discovering that phosphorus is the ideal material, but the function of the blue LED remains fundamental. p>
Currently the two most important methods; simple production of white light LEDs are the RGB combination system and the use of phosphorus. The method that uses the RGB combination bases its effectiveness on the concept of color fusion of light, using more than once; chips that emit red, green, and blue wavelengths, which combine to produce white light. The method of production of LEDs that uses phosphorus is based on the fusion of the blue light of a classic Led, with the light of one with phosphorus that emits a broad band of wavelengths that cover the spectrum from green to yellow, until to red, to get white light. p>
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In 2008, Philips ceased research on compact fluorescents and started to invest most of its budget for research and development of Led and in September 2009 & egrave; was the first company to present LED lamps to replace the classic 60 Watt Edison bulb. Naturally, at the beginning the Led lamps have greatly changed the chromaticity; of the light of incandescent lamps that were replacing and it is; & Egrave; A standard has been developed, ANSI C78.377-2008, which specifies the recommended color ranges for products used in LED lighting and prescribes laboratory test and analysis methods. The Energy Star company in 2009 began to label the packs of LED lamps produced, with data that meet a set of standards, the IRC or, in the English terminology CRI, (Chromatic Resolutions Index), the expectation of life, color and constancy of performance. The intent of the program is was to reduce consumer concerns as a result of quality; variable of products and to guarantee their transparency.