In 1923, scientists Rousseff (O.W.Lossew) found that SiC P-N junction has a one-way conductive and luminous phenomenon; after 1955, R.J.Haynes proposed the semiconductor germanium P-N junction Research Report, G.A.Wolff studied the luminescence phenomenon of gap; in 1968, American Monsanto company and HP company for the first time to produce red LED, LED officially became an electronic the product into the market. LED have many advantages:
(1) Save energy: the spectrum of LED is almost all concentrated in the visible light band, the luminous efficiency is 80 - 90%. The LED and the ordinary incandescent lamp, energy-saving lamps and T5 three spiral fluorescent lamp has made a comparison, results show that the optical efficiency of ordinary incandescent lamp life is 12lm/w, less than 2000 hours, the light effect of spiral energy-saving lamp for 60lm/w, life expectancy of less than 8000 hours, T5 fluorescent lamp is 96Alm/ w, life for about 10000 hours, white LED and 5 mm in diameter is 20 28lm/w, the service life can be more than 100000 hours. It is also predicted that the future of the LED life limit will be infinite.
It is believed that the energy-saving lamp energy-saving 4/5 is a great feat, but also energy saving energy saving lamp LED than 1/4, this is the great reform of solid light source. In addition, LED has other advantages, high quality of light, basically no radiation, is a typical green lighting source; reliable and durable, maintenance costs are extremely low, etc.. Because LED has more than other solid light source is also unable to match the characteristics of the 10 years after the LED will be the mainstream of the lighting industry.
(2) Safety and environmental protection: LED of the working voltage is low, more than 1.4 - 3V; ordinary LED operating current is only 10mA, ultra high brightness 1A. LED in the production process do not add "Mercury", also do not need to inflate, do not need a glass shell, the impact of good, good resistance, not easy to break, easy to transport, very environmentally friendly, is known as green energy".
(3) Long service life: LED volume is small, light weight, shell is epoxy resin package, not only can protect the internal chip, but also has the ability to focus on the light. LED service life is generally between 50 thousand - 100 thousand hours, because LED is a semiconductor device, even if it is a frequent switch, it will not affect the service life. At present, the main use of household lighting is incandescent lamps, fluorescent lamps and energy-saving fluorescent lamps.
(4)Fast response: LED frequency response of F tau and injected minority carrier lifetime tau MC, such as GaAs material LED, the tau 1 MC in general 10ns range, the response frequency is about 16 160MHz, so the high frequency response for the 6.5MHz to display the video signal that has been enough, this is one of the key factors to realize large screen video LED.
At present, the LED response time has reached a minimum of 1 s, the general is a few milliseconds, about the response time of ordinary light source 1/100. Therefore, it can be used in many high frequency environment, such as car brake lights or lights, can shorten the braking time of the vehicle, so as to improve the safety of the vehicle.
(5) The high luminous efficiency: luminous efficiency of incandescent lamp, halogen lamp for 12-24lm/w (LM / W), the light effect of the fluorescent lamp is 50 70lm/w, sodium lamp light effect is from 90 to 140lm/w, most of the energy into heat. The optical efficiency of LED can reach 50 to 200lm/w, and the color of the light is good and the spectrum is narrow.
(6) The size of the LED element is small: it is more convenient for the layout and design of various equipment, and it can better realize the effect of "no light source" in the night scene illumination.
(7) LED ray energy concentration is high: concentrated in a smaller wavelength window, high purity.
(8) The LED is pointed to the intensity: the intensity of the light is much lower than the traditional light source.
(9) LED low voltage DC power can be driven: with the advantages of low load and low interference, the use of the environment is low.
(10) A good control of the light emitting spectrum can be well used in the museum and exhibition hall of the local or key lighting.
(11) Can control the semiconductor light emitting layer, the size of the width of forbidden band semiconductor materials: thus emit different colors of light, and high chroma.
(12) the color of the color is high: no damage to the eyes.
However: as a new technology, semiconductor lighting industry is still in a rapid development stage, scientific and technological progress made us feel happy, but we must also realize that both the technology and industry regulations, compared with the traditional light source, are still not mature. To truly achieve with LED instead of the traditional light source, there is a long way to go, believe that by promoting the healthy and orderly development of the entire industry, and constantly accelerate the pace of application of traditional industries, and promote the adjustment of industrial structure, the quality of life for people to open the green.