First  LED Summary
一accepted什么意思中文  LED概述
LED (Light Emitting Diode), light-emitting diode, is a solid state semiconductor devices, which can be directly converted into electricity to light. LED is the heart of a semiconductor chip, the chip is attached to one end of a stent, is the negative side, the other end of the power of the cathode, the entire chip package to be epoxy resin. Semiconductor chip is composed of two parts, part of the P-type semiconductor, it inside the hole-dominated, the other side is the N-type semiconductor, here is mainly electronic. But linking the two semiconductors, among them the formation of a "PN junction." When the current through the wires role in this chip, will be pushing e-P, P zone in the hole with electronic composite, and then to be issued in the form of photon energy, and this is the principle of LED luminescence. The wavelength of light that is the color of light, is formed by the PN junction of the decisions of the material.
LED（Light Emitting Diode），发光二极管，是一种固态的半导体器件，它可以直接把电转
化为光。LED的心脏是一个半导体的晶片，晶片的一端附在一个支架上，一端是负极，另一端连接电源的正极，使整个晶片被环氧树脂封装起来。半导体晶片由两部分组成，一部分是P型半导体，在它里面空穴占主导地位，另一端是N型半导体，在这边主要是电子。但这两种半导体连接起来的时候，它们之间就形成一个“P-N结”。当电流通过导线作用于这个晶片的时候，电子就会被推向P区，在P区里电子跟空穴复合，然后就会以光子的形式发出能量，这就是LED发光的原理。而光的波长也就是光的颜，是由形成P-N结的材料决定的。
Second  LED history and development
50 years ago, people have to understand semiconductor materials can produce light of the basic knowledge, the first commercial diodes in 1960. English is the LED light emitting diode (LED) acronym, and its basic structure is an electroluminescent semiconductor materials, placed in a wire rack, then sealed with epoxy resin around, that is, solid package, Therefore, the protection of the internal batteries can play the role of line, so the seismic performance LED good.
LED is the core of the P-type semiconductor and components of the N-type semiconductor chips, the P-type semiconductor and N-type semiconductor between a transition layer, called the PN junction. In some semiconductor materials in the PN junction, the injection of a small number of carrier-carrier and the majority of the extra time will be in the form of light energy to release, thus the power to direct conversion of solar energy. PN junction on reverse voltage, a few hard-carrier injection, it is not luminous. This use of injection electroluminescent diodes is produced by the principle of light-emitting diodes, commonly known as LED. When it in a positive state of the work (that is, at both ends with forward voltage), the current flows from the LED anode, cathode, semiconductor crystals on the issue from the ultraviolet to infrared light of different colors, light and the strength of the currents.
Instruments used for the first LED light source instructions, but all kinds of light colored LED lights in traffic and large screen has been widely applied, have a very good economic and social benefits. The 12-inch red traffic lights as an example, is used in the        United States have long life, low-efficiency 140 watt incandescent lamp as a light sour
ce, it produced 2,000 lumens of white light. The red filter, the loss-90 percent, only 200 lumens of red light. In the light of the new design, Lumileds companies have 18 red LED light source, including the loss of circuit, a total power consumption of 14 watts to generate the same optical effect. Automotive LED lights is also the source of important areas.
For general lighting, people need more white light sources. The 1998 white LED successful development. This is the GaN LED chip and Yttrium Aluminum Garnet (YAG) package together cause. GaN chip of the Blu-ray (λ p = 465nm, Wd = 30nm), made of high-temperature sintering of the Ce3 + YAG phosphors excited by this Blu-ray after irradiating a yellow, the peak 550 nm. Blue-chip installed in the LED-based Wanxing reflection in the cavity, covered with a resin mixed with YAG thin layer, about 200-500 nm. LED-based tablets issued by the Blu-ray absorption part of the phosphor, the phosphor another part of the Blu-ray and a yellow light mixed, can be a white. Now, the InGaN / YAG white LED, YAG phosphor by changing the chemical composition of the phosphor layer and adjust the thickness of the 3500-10000 K color temperature can be colored whit
e. This blue LED through the method by white, constructed simple, low-cost, high technology is mature, so use the most.
The development of LED display can be divided into the following phases: first phase 1990 to 1995, mainly monochrome and 16 color graphics screen. Used to display text and simple images, mainly used in railway stations, financial securities, banks, post offices and other public places, as public information display tools. The second stage is from 1995 to 1999, there have been 64, 256 level gray-scale two-color video screen. Video control technology, image processing, optical fiber communication technology applications will enhance the LED display to a new level. LED display control LSI chips special at this time developed by domestic companies, and can be applied. The third stage, from 1999, red, pure green, blue LED in bulk into China, while domestic enterprises in-depth research and development work, using red, green, and blue LED production of full-color display has been widely used , poured into sports stadiums, convention centers, squares and other public places, which will bring the domestic large-screen full-color era. With the rapid development of LED materials market, surface mount
device is available from 2001, mainly used in indoor full color, and its high brightness, colorful, low temperature characteristics, the point spacing can be adjusted by different price Requirements were accepted, in just two years time, product sales have more than 300 million yuan, surface mount full-color LED display application market entered the new century. To meet the 2008 Olympic Games, "downsizing" plan, Liard developed a surface mount dual color displays, a lot of time for the training center and game scoring. Full color in Olympic venues, in order to tighten investment, full color way is mostly detachable, live during the Olympic Games as a tool can be used for rental after the event, as the performance of national policies such as public places, tools released by In this way cost recovery as soon as possible. On the market, China's accession to WTO, Beijing's successful Olympic bid and so on, into the development of LED display industry, a new opportunity. Domestic LED display market continues to grow, currently in the domestic market, domestic LED display market share of nearly 95%. LED display the international market capacity is expected to 30% a year growth rate. Currently, LED display manufacturers concentrated primarily in Japan, North America, China LED manufacturers
in which the insignificant share of exports. According to incomplete statistics, the world, there are at least 150 manufacturers full color, in which products are complete, the larger company has some 30 or so.

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