For nearly two years with the Pulsar , develop projects for indoor and outdoor lamps, whose light source is 100% LED. Following you can see some of the products result of this work, some of them were selected and awarded in several design competitions and widely followed by the trade press as you can see from the press review . After the images a bit of history and explanations relating to LED technology and to their characteristics.
Catalogue Lamps 2009 Led Pulsar
LEDs
A Light-Emitting Diode ( LED) light source is a semiconductor. LEDs are used as indicator lights in many devices, and are increasingly used for lighting. Introduced in 1962 as an electronic component, the first LEDs were low-intensity red light, but modern versions are available in the entire visible wavelength, ultraviolet and infrared, with a very high brightness.
LED based on semiconductor diode. When a diode is forward biased (turned on), the electrons are able to recombine with holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and color of light (corresponding to the photon energy) is determined by the energy gap of the semiconductor. An LED is usually small (less than 1 mm2).
LEDs have many advantages over incandescent light sources, including lower energy consumption, longer life, improved robustness, small size, faster switching, and a longer life and expectations. However, they are relatively expensive and require more precise current and thermal management compared to traditional light sources. Current LED products for general lighting, they are more expensive to buy fluorescent light sources of comparable production.
They are also used in various applications as substitutes for traditional light sources in the automobile sector (especially indicators) and on road signs.
After the introduction of new models to its highest potential, the LEDs have begun to invade other areas, such as lamps, home office and street lighting, especially with solar lanterns.
A bit of history
Electroluminescence was discovered in 1907 by the British experimenter HJ Round of Marconi Labs, using a crystal of silicon carbide and Russian Oleg Vladimirovich Losev that reported on the creation of an LED in 1927. His research has been distributed in Russian, German and English scientific journals, but has not been made practical use of the discovery for several decades. Rubin Braunstein of the Radio Corporation of America reported on infrared radiation from gallium arsenide (GaAs) and other semiconductor alloys in 1955. Braunstein observed infrared radiation generated by simple diode structures using gallium Antimoniuro (gasba), GaAs, indium phosphide (InP), and silicon-germanium (SiGe) alloys at room temperature and 77 kelvin.
In 1961, investigators Robert Biard and Gary Pittman working at Texas Instruments, found that GaAs emitting infrared radiation when electric current was applied and received a patent for the infrared LED.
The first practical visible-spectrum (red) LED was developed in 1962 by Nick Holonyak Jr., while working at General Electric Company. Holonyak is seen as the "Father of Light-Emitting Diode." M. George Craford, a former graduate student Holonyak, invented the first yellow LED and improved the brightness of red and orange-red LED by a factor of ten in 1972.
In 1976, TP Pearsall created the first high brightness and high efficiency LEDs for fiber-optic telecommunications with the application of new semiconductor materials specially adapted to the wavelength of optical fiber transmission.
Until 1968 LEDs visible and have been extremely costly, in the order of $ 200 per unit, and so had little practical application. The Monsanto Company was the first organization to produce visible LEDs in series, using gallium arsenide phosphide in 1968 for the production of red LEDs suitable for indicators. Hewlett Packard (HP) has introduced the LED in 1968, initially with GaAsP provided by Monsanto, the technology proved to have the potential for alphanumeric displays and was built by HP in the first electronic calculators. Durability and reliability
solid state devices, such as LEDs are wearing very little if operated at low currents and low temperatures. Many of the LED produced in the years 1970 and 1980 are still in service today. Lives reported are typical 25,000 to 100,000 hours, but the heat and current settings can extend or reduce this time significantly.
The most common symptom of damage to the LED is to reduce the production of light and progressive loss of efficiency. With the development of high-power LED devices are subjected to temperatures high compared to traditional devices. This causes stress on the material and can cause premature degradation of the emission of light. To quantitatively classify the life of an LED in a standardized way has been suggested to use the terms L75 and L50, which is the time it takes for a given LED up to 75% and 50% light output, respectively, L50 is equivalent to half life of the LED.
high-power LED
A high-power LEDs (HPLED) can be activated by currents of hundreds of mA to more than one amp, compared to tens of mA for normal LEDs. Since overheating is destructive, HPLEDs must be mounted on a heat sink to dissipate heat. If the heat from a HPLED is not removed, the device will burn in seconds. A single HPLED can often replace an incandescent bulb in a flashlight, or used in an array to form a powerful LED lamp.
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