It’s been a century since electroluminescence was first demonstrated in a lab and more than five decades have passed since the invention of the light emitting diode (LED) created by Nick Holonyak, Jr. who was then at General Electric.
Holonyak achieved success in a technique of synthesizing gallium phosphide (GaAsP) crystals which, when turned on, produced the appearance of a dim however “tunable” glowing red (Massachusetts Institute of Technology 2004). In the beginning, LEDs were used in consumer products that were primarily indicator lights for power-on in portable calculators TVs, music players, and other sets.
Finding other consumer-oriented products was slow. For instance, a decade could pass before an Holonyak student discovered a method to increase light output by ten times. However, in modern times the energy efficiency, the increased brightness, endurance and significantly faster switching times of LEDs have paved way for their use in rooms lighting as well as scrolling text displays video displays, automotive lamps, outside lighting and traffic lighting. This paper analyzes the likely opportunities for LED lighting specifically in comparison with the present alternatives, which are fluorescent lamps.
The reason LED Technology is energy-efficient
LED lighting is a key component in retrofitting your home to make it more eco-friendly, primarily in the sense of the reduction of power demands. As they to the class of semiconductors that have replaced transistors, LEDs are able to work at very low power levels.
The first LEDs, which were employed in the first analog wristwatches, and also to indicate the the power-on status in desk and hand-held calculators as well as portable radios, and cassette players, ran at between 30 and 60 milliwatts. It was the beginning century (1999) before die sizes grew large enough to accommodate even one Watt. This power improvement also demanded the development of the mounting of LED dies on slugs made of metal.
Technology in LED lighting has matured to the point where commercially-available products already exceed the luminosity-to-power ratio of incandescent bulbs and even standard fluorescent lights, presently the most widely-used alternative.
Incandescent bulbs with a rating of 60 to 100 watts release approximately 15 lumens/watt (lm/W) while regular, 40-watt fluorescent bulbs can reach up 100 lumens per watt. The year 2002 saw Philips Lumileds brought to market five-watt LEDs with a rating of 18-22 lm/W. From 2003 until the year 2010, American, Japanese, Korean and Taiwanese manufacturers increased the standard, initially reaching 65 lm/W, and then in the beginning of 2010, achieving the 208 lm/W mark in laboratory conditions. For commercially-available products, 100 lm/W was already available in 2009.
A hundred-lumen level is an essential measure by itself since it is the Illuminating Engineering Society considers that illumination level to be the minimum for applications of class C: “Working spaces where visual tasks are not often performed” (Williams 1999 Table 1).
Because 1 lumen/square metre equals 1 lux, and 1 lumen/square foot equals 1 foot-candle. Illuminance can be measured in a millimetre away from the source and the distance between ceiling lights to the tables or chairs in which people read is at least 3 metres. The IES guidelines go up to 2,000 lumens in classes F for reading small print or materials with low contrast. This is the reason why fluorescent lamps are typically set up as sets comprising at minimum two in offices and residential spaces where people need to read.
Based on the current specifications of 20-350 milliamps (the one for powerful LED light sources) it is evident that the technology can already produce acceptable lumens under 5 watts under the normal household current of 220 volts however under cold lab conditions.
In the event it is possible that R & D can find methods to transfer this significant power efficiency into environments with moderate to high humidity and temperature LED lighting will contribute in the search for solutions that are sustainable in the near future, especially as the cost of energy continues to rise.
First, the range of colours available is expanding. In the 1990s, for instance gallium arsenide (GaN) LEDs were made through Metal Oxide Chemical Vapor Deposition of an ultra-thin layer this alloy onto sapphire. It resulted in design that reflected 90 percent of the light emitted from the active layer.
The luminance nearly doubled during the same when the device complete (with it being green) the primary color palette that LED lighting can offer (MarkTech OptoElectronics, 2010,). Outdoor applications that require daytime usage such as traffic lights, became feasible.
Additionally, LED lighting has significant advantages over current lighting, particularly in terms of pollution or ultraviolet radiation. The class of LED lighting is precisely tuned that it is unable to emit any UV rays (Toolbase.org 2001).
However there is a consensus that each of the Health Protection Agency (2008) as well as the National Electrical Manufacturers Association (NEMA) acknowledge they emit UV radiations due to the manner in which the technology works: an electric current stimulates mercury vapour then causing UVR to activate the phosphors that are encased in the interior in the tube that is fluorescent.
As of now, laboratory tests have shown that UV-C, which is extremely dangerous, is taken up in the glass fitting while both UV-A as well as UVB radiation that leaks are lower than the thresholds to experience acute adverse side effects (malignant Melanoma being the most severe).
However, there is a Support Group for Sun Sensitive People (2006) asserts an argument that the bright light in shopping centers is comparable to 50percent of the midday UV radiation that is a part of the summer sun, which poses a risk for those with sensitive skin or suffer from conditions such like lupus or various other sensitivities to sunlight. However, there is no question that the disposal of fluorescent lamps with short lives lamps is a mercury-contamination problem for landfills.