A. LED tube,the light-emitting structure and principle, Led tube is composed of a Led. 50 years ago, people have to understand the semiconductor material can produce light of the basic knowledge, the first commercial LED production in 1960. LED in the English light emitting diode (LED) acronym, and its basic structure is an electroluminescent semiconductor material, placed in a wire rack, then surrounded by epoxy sealed, can protect the internal core wire effect, so the seismic performance LED. LED tube light-emitting diode from the core by the p-type semiconductor and n-type semiconductor chip formed in the p-type semiconductor and n-type semiconductor between a transition layer, called the pn junction. In certain semiconductor materials, PN junction, the injection of minority carrier and majority carrier recombination, when will the excess energy released in the form of light to convert light energy directly into electrical energy. PN junction reverse voltage, minority-carrier injection is difficult, it is not light. The use of injection electroluminescent diodes called the principle of making light emitting diodes, commonly known as LED. When it is in working condition when a positive (that ends with a positive voltage), current from the LED anode to the cathode, the semiconductor crystals to the making of different colors from the ultraviolet to infrared light, light intensity and current.
B.LED tube light source characteristics
1. Voltage: LED tube using low voltage power supply, power supply voltage between 6-24V, according to the products vary, so it is more secure than the use of high voltage power supply, especially for public places.
2. Performance: Led tube light consumes energy efficient than incandescent lamps with 80% reduction
3. Applicability: Led tube for home lighting, commercial lighting, and other places.
4. Stability: 10 million hours, the light fades to 50% of the initial
5. Response time: incandescent millisecond response time, LED tube lights nanosecond response time
6. Led tube of environmental pollution: no harmful metal mercury
7.Led tube Color: change the current can change color, light-emitting diodes by chemical modification methods to easily adjust the material's band structure and band gap, to achieve multi-color light orange red Huanglv Lan. Such as the small current when the red LED, as the current increases, you can turn to orange, yellow, and finally to the green
8. Price: LED tube is expensive, compared to incandescent lamps, a few LED's price to the price of incandescent lamps with a considerable, and often each signal to be 300 to 500 by the diode on the form.
C.monochromatic LED and history of the types of
The first application of the principle of semiconductor PN junction light-emitting LED light source made of 60 came in the early 20th century. Use at the time of the material is GaAsP, fat red (λp = 650nm), the drive current of 20 mA, the luminous flux is only a few lumens per thousand, and the corresponding luminous efficiency of about 0.1 lumens / watt. The mid-70s, the introduction of elements of In and N, the LED produces green (λp = 555nm), yellow (λp = 590nm) and orange (λp = 610nm), luminous efficiency is also increased to 1 lumen / watt. To the early 80s, there's GaAlAs LED light source, so red LED light efficiency of 10 lumens / watt. Early 90s, red light, yellow light GaAlInP and hair green and blue GaInN successful development of two new materials to make LED light effect has been greatly improved. In 2000, the former is made of LED in red, orange area (λp = 615nm) of the luminous efficiency of 100 lm / W, which made the green zone LED (λp = 530nm) of the luminous efficiency can reach 50 lm / watts.
D.the application of monochromatic LED Tube
Instrumentation for the first LED light source direction, then a variety of light-colored LED in traffic lights and large screen has been widely used and produced good economic and social benefits. 12-inch red traffic lights, for example, is used in the United States would have long life, low-efficiency 140-watt incandescent lamp as a light source, it produces 2000 lumens of white light. The red filter, 90% light loss, only 200 lumens of red light. In light of the new design, Lumileds has used a red LED light source 18, including circuit losses, including a total power of 14 watts of light to produce the same effect.
Automotive LED lights are also important areas of light application. In 1987, China began to install in the car brake light, the LED response speed (ns), at an early stage so that the trailing vehicle drivers know that driving conditions and reduce rear-end accidents.
In addition, LED lights in the outdoor red, green, blue full-color display, mini flashlight key chain-type fields have been applied.
E. The development of white LED tube
For general lighting purposes, people need a white light. 1998 glowing LED developed. This is the GaN LED chip and yttrium aluminum garnet (YAG) packaged together to make. GaN blue chip fat (λp = 465nm, Wd = 30nm), made of high-temperature sintering of YAG phosphors with Ce3 + excited by this yellow and blue light emission, peak 550nm. Blue LED substrate cavity installed in the reflective bowl, cover with thin layer of resin mixed with YAG, about 200-500nm. LED blue part of the substrate to be issued by the phosphor absorbed, and some blue and yellow light emitted phosphor mixture can be too white. Now, for the InGaN / YAG white LED, YAG phosphor by changing the chemical composition and adjust the thickness of the phosphor layer can be obtained color temperature 3500-10000K in colored white. The first has been the commercialization of products for blue chip with YAG yellow phosphor, the luminous efficiency of its best about 25 lm / W, YAG and more Asian companies to Japan's import prices in 2000 yuan / kg ; The second is the Japanese Sumitomo Electric has developed the material to ZnSe white LED, but less luminous efficiency. Can be seen from the table, certain types of white LED light source can not do without four phosphor: the earth three primary colors red, green, blue pink and yellow and pink garnet structure, in the future more promising is the three-wavelength light , that is inorganic UV chip plus three color RGB phosphors, white light LED for the package is expected this year, three-wavelength white LED drive commercialization opportunities. But here trichromatic phosphor particle size requirements are relatively small, the stability requirements are also high, specific applications are still being explored.
F. Industrial Overview
In the LED tube industry, Nichia was the first use of the technology process developed different wavelengths of high-brightness LED, and blue-violet semiconductor laser (Laser Diode; LD), holds the industry heavyweight blue LED patent industry. Nichia achieved in the blue LED production and electrode structure, and many other basic patent, adhere to not provide authorization, using only its own production strategy, intended to monopolize the market, making the blue LED high prices. But others already have substantial production capacity of the industry disagree, some Japanese LED industry believes that Nichia Chemical's strategy is to make the Japanese blue and white LED tube in the competition, gradually Europe, America and other countries to seize the initiative LED industry, will Japanese LED industry as a whole will cause serious injury. So many firms will do everything possible to carry out the development of blue LED production. At present, except at the chemical and Sumitomo Electric Asia, there Toyoda Gosei, Luo Mu, Toshiba and Sharp, American Cree, 3 large lighting plant singular world, Philips, Osram, and HP, Siemens, Research, EMCORE invested so production of the product development, the promotion of the industrialization of white LED products, the market has played a positive role.
