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• LED outlined
• LED history
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• LED features
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LED (Light Emitting Diode), LED, is a solid Semiconductor device, it can be directly converted into electricity to light. LED is a semiconductor at the heart of the 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 guitar ". 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.

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, so to Internal protection played the role of core-line, so the seismic performance LED good.

LED diode 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 watts incandescen as a light source, 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 white. This blue LED through the method by white, constructed simple, low-cost, high technology is mature, so use the most.
In the 1960s, the use of science and technology workers semiconductor PN junction of The principle of developing a LED light-emitting diodes. At that time, the development of LED, the materials used are GaASP, its luminous color is red. After nearly 30 years of development, and now we are very familiar with the LED, has been sent to red, orange, yellow, green, blue, and other shade. However lighting necessary for white LED light only in recent years to develop, readers here to tell us about lighting with white LED.

1, the visible light spectrum and the relationship between the white LED .
It is weeks, the wavelength of visible light spectrum range of 380 nm ~ 760nm, is the human eye can feel the Qise light - red, orange, yellow, green, green, blue, purple, but seven colors of light is all their own A Danse Guang. For example, the red LED of the peak wavelength of 565 nm. In the visible spectrum of light is not white, because white is not Danse Guang, but by a variety of Danse Guang of the composite light, as the sun alone from seven Danse Guang of the white light, white and color television sets in Light also by the three primary colors red, green, blue synthesis. Thus, if a white LED, which should include the entire spectrum of visible spectral range. But to create such a performance of the LED, in the current process under the conditions is impossible. According to the people of visible light, human eyes can see the white light, at least two-hybrid, that is, the wavelength LED (light blue + yellow light) or three-wavelength LED (light blue-green + + red light) model . These two models of the white, and blue light needed, so intake of blue-white light manufacturing has become the key technology that the current major LED manufacturing companies chasing the "Blu-ray technology." The current international control "Blu-ray technology" only a few manufacturers, such as Japan's Nichia Chemical, Japan's Toyota synthesis, the United States CREE, Germany OSRAM , and so on, so the white LED application, in particular the high-brightness white LED in China to promote a process there.

2, white LED technology structure and the white light source .
For general lighting, in the process structure, the white LED is usually formed by the two methods. The first is to use the "Blu-ray technology" and phosphor with a white; Dan Seguang second is a variety of hybrid method. Both methods have been able to produce white light devices. The first method produce white light system as shown in Figure 1, Figure LEDGaM chip in the Blu-ray (λ p = 465NM), and it YAG (Yttrium Aluminum Garnet) phosphor package together, when the phosphors excited by the Blu-ray After a yellow light and as a result, blue and yellow light hybrid form of white (LED constitute the structure shown in Figure 2). The second method used different shade of the chip package together, through the mixed-colored and have a white light.

3, white LED lighting source of the new application .
To illustrate the characteristics of white LED, first take a look at the lighting currently used source of lighting conditions. Incandescent and Luwu Deng, the optical effect for 12 to 24 lumens / W; fluorescent and HID lamps light efficiency of 50 to 120 lumens / watt. The white LED: In 1998, white LED light effect only 5 lumens / watt, by 1999 had reached 15 lumens / watt, with the general target of 200, close to home, and in 2000, the white LED light effect Has reached 25 lumens / W, and Lu Wudeng close to the target. A company forecast that by 2005, LED light efficiency up to 50 lumens / watt, such as Kay Dili Optoelectronics Technology (http://www.kvidi.com) production of 1 W white lights already reached 60 lumens / watt, In 2015 when, LED optical effect is expected to reach 150 to 200 lumens / watt. At that time, the work of the white LED can Daan Pei current level. This shows that the development of writers with white LED lighting source, Jiang Cheng may be the reality.

Common use of incandescent lighting and Luwu Deng Although cheap, but low-efficiency (HEC's thermal effects in vain power consumption), short life and safeguard heavy workload, but with a white LED lighting, not only high-efficiency, and Long life (100,000 hours of continuous work over time), almost no maintenance. At present, Germany Hella companies use the aircraft developed a white LED reading lights; Australian Capital Canberra have spent a street for a white LED lights lighting ; China's urban traffic management lights are also used to replace the early white LED light traffic order. It can be foreseen the near future, the white LED into the family will replace the existing lights.

LED light source with the use of low-voltage power supply, energy-consuming less, applicability, high stability, response time is short, the environment pollution-free, multi-color LED, and so on the merits, although the prices of expensive than the existing lighting equipment, it is still being considered Inevitably replace the existing lighting devices.



The inherent characteristics of LED decided it is the ideal source to replace the traditional light sources, it has a wide range of uses.

Small size

LED is basically a very small chip is packaged in epoxy inside, so it is very small, very light.

Low power consumption

LED power consumption is very low, generally the work of LED voltage is 2-3.6 V. Current work is 0.02-0.03 A. That is to say: it's electricity consumption does not exceed 0.1 W.

Long life

The proper current and voltage, LED life up to 100,000 hours.

High brightness, low-calorie

Environmental

LED by making non-toxic materials, unlike Fluorescent containing mercury will cause pollution, LED can recycling.

Durable

LED is fully in epoxy resin inside the package, than light bulbs and fluorescent tubes are strong. HEC has not loosened in some of these features make LED can be said to be not damaged.



1, according to LED luminous color sub-

LED by the luminous colors, can be divided into red, orange, green (and sub-Yellow-green, the standard green and pure green), Blu-ray, and so on. In addition, some light-emitting diode contained in two kinds of chips or three colors.

According to the LED to light-doped scattering of doped or not, colored or colorless, the various colors of light-emitting diodes can be divided into colored transparent, colorless, transparent, non-ferrous metals and scattering colorless scattering four types. Scattering of light-emitting diodes and light up to do with.

2. Smooth LED according to the characteristics of

Smooth LED according to the characteristics of a round lights, side lights, rectangular, LED face, side of the surface with micro-management, and so installed. Diameter round lights into the φ2 mm, φ4.4 mm, φ5 mm, φ8 mm, φ10 mm and φ20 mm, and so on. Foreign countries are usually the φ3 mm LED recorded as T-1; to φ5 mm recorded as the T-1 (3 / 4); to φ4.4 mm recorded as the T-1 (1 / 4).

By the half-value angle size can be estimated round luminous intensity distribution angle.

Angle from the luminous intensity distribution to the three categories:

(1) high-directional. Packaging is pointed epoxy general, or with metal reflector cavity package, without scattering of Canada. Half-value angle of 5 ° ~ 20 ° or less, with a high point of the light source for local use or for the detection and optical components for automatic detection system.

(2) standard. Normally used for light, the half-value angle of 20 ° ~ 45 °.

(3) scattering type. This is the larger perspective of the light, half-value angle of 45 ° ~ 90 ° or greater, the scattering of the large amount.

3. According to the structure of light-emitting diodes-

on the structure of light-emitting diodes at a full-epoxy encapsulation, epoxy base metal packaging, ceramics and glass packaging base epoxy package structure.

4. And the luminous intensity of the current work

And the luminous intensity of the current work of a general brightness of the LED (luminous intensity of 100 mcd); luminous intensity in the 10 ~ 100 mcd between the high-brightness light-emitting diode called. General LED current in the work of more than 10 mA to dozens mA, and low-current LED current work in the following 2 mA (with the general brightness LED same).
In addition to the above classifications, but also the chips according to the functions of sorting and classification methods.


Chip and what is led chip?

1, LED chip role:

LED LED chips for the main raw material, LED luminescence to rely mainly on the chip.

2, LED chip component
Mainly arsenic (AS) Aluminium (AL) gallium (Ga) indium (IN) phosphorus (P) of nitrogen (N) Sr (Si) that several elements of a number of components.

3, LED chip classification

1, the brightness at:
A, the general brightness: R ﹑ H ﹑ G ﹑ Y ﹑ E, etc.
B, high-brightness: VG ﹑ VY ﹑ SR, etc.
C, ultra-high brightness: UG ﹑ UY ﹑ UR ﹑ UYS ﹑ URF ﹑ UE, etc.
D, not visible light (infrared): R ﹑ SIR ﹑ VIR ﹑ HIR
E, the infrared receiver: PT
F, photocell: PD
2, the composition of sub-elements:
A, the dual chip (P ﹑ Ga): H ﹑ G, etc.
B, ternary chip (P ﹑ ﹑ gallium arsenic): SR ﹑ HR ﹑ UR, etc.
C, 4 yuan chip (P ﹑ ﹑ aluminum indium gallium ﹑): SRF ﹑ HRF ﹑ URF ﹑ VY ﹑ HY ﹑ UY ﹑ UYS ﹑ UE ﹑ HE, UG

4, LED chip features (detailed in the table below on)

LED chip models luminous colors of elements in wavelength (nm) chip models luminous colors of elements in wavelength (nm)
SBI blue lnGaN / sic 430 HY super-bright yellow AlGalnP 595
SBK than-blue lnGaN / sic 468 SE highlight Jiese GaAsP / GaP 610
DBK than-blue GaunN / Gan 470 HE Chaoliang Jiese AlGalnP 620
SGL Green Green lnGaN / sic 502 UE-Jiese most AlGalnP 620
DGL more green-Green LnGaN / GaN 505 URF the brightest red AlGalnP 630
DGM more green-Green lnGaN 523 E Jiese GaAsP/GaP635
PG-Green GaP 555 R red GAaAsP 655
SG Green GaP 560 SR standards than the bright red GaA / AS 660
G green GaP 565 HR super-bright red GaAlAs 660
VG than the bright green GaP 565 UR the brightest red GaAlAs 660
UG most bright green AIGalnP 574 H high-GaP 697
Y yellow GaAsP/GaP585 HIR infrared GaAlAs 850
VY than the bright yellow GaAsP / GaP 585 SIR infrared GaAlAs 880
UYS the brightest yellow AlGalnP 587 VIR infrared GaAlAs 940
UY most bright yellow AlGalnP 595 IR infrared GaAs 940

5, pay attention to other matters and

1, LED chip manufacturers name: A, Guanglei (ED) B, the League of Nations (FPD) C, tripod yuan (TK) D, China, (AOC) E, Hankuang (HL) F, AXT G, Jia-
2, LED chips used in the production process should pay attention to static electricity protection.
6, added
LED display (LED panel): LED is light emitting diode, LED stands for, or LED. It is through control of a semiconductor light-emitting diode display, to display text, graphics, images, animation, Quotes, video, video signals, and other information display screen.
LED display is divided into by display and video displays, are composed of LED matrix block. Graphic displays can be synchronized with the computer display Chinese characters and English text and graphics, video display using micro-computer control, by, and image-mao, in real-time, synchronization, clear message broadcast mode of transmission of information, also revealed that two Victoria, three-dimensional animation, video, TV, VCD programs and on-site fact. LED display screen colorful, strong sense of three-dimensional, static such as painting, moving as the film is widely used in stations, wharves, airports, shopping malls, hospitals, hotels, banks, securities market, construction market, auction houses, industry and enterprise management Other public places.
The advantage: high brightness, low voltage and power consumption of small, micro and easy to match with the integrated circuit, driving a simple, long life, impact-resistant, stable performance.



7, MOCVD market surveys,

At present - MOCVD equipment manufacturers have two major:
1. AIXTRON Germany (British THOMAS SWAN AIXTRON company has been acquired) cumulative sales of 1,000 units
April 24, 2007, AIXTRON Taiwan Can round photoelectric (Formosa Epitaxy) announced that the 1000th AIXTRON Taiwan CCS MOCVD (30x2-inch) round Can the factory set up, expand the circle Can the existing AIXTRON equipment lineup (including Several AIX 2400/2600G3 HT)
The latest model: AIX 2800G4-R AlGaInP MOCVD
2. VEECO the United States (U.S. EMCORE company mergers and acquisitions).
One AIXTRON companies (including THOMAS SWAN) accounts for about 60-70 per cent of international market share, while VEECO companies accounted for 30-40 per cent.
Other major manufacturers, including Japan's NIPPON Sanso and Nissin Electric, its basic limited to the Japanese domestic market. For example, Japan's Asian companies and companies such as Toyota production of the GaN-MOCVD equipment is not sold on the market, only for personal use, while Japan SANSO company's GaN-MOCVD equipment excellent performance, but only the Japanese market. From equipment performance in terms of Asian companies on the material quality of production equipment and device performance, is far superior to AIXTRON and EMCORE equipment. Calculated according to production capacity, GaN-MOCVD equipment in the global market are mainly distributed as follows: 48% in China Taiwan, the United States 15 percent, Japan 15%, 11% of South Korea, mainland China 7%, 4% of the EU.
PS: the first is to make the MOCVD British company Thomas Swan
PS: in the village repair the use of MOCVD SANSO Japan developed the Blu-ray machines currently in the village repair company in the United States CREE

Major chip manufacturers to purchase Germany and the United States AIXTRON EMCORE two suppliers of MOCVD equipment to six and nine of the majority, the price of each piece of equipment in the 700,000 U.S. dollars to 100 million dollars. The recent introduction of 19 enterprises and 21 aircraft, and enterprises have started VEECO equipment produced by the more advanced 24 MOCVD equipment.
8, Note (terminology)

1. Temperature
King is the color temperature study what ?we know, usually by the human eye to see the light, the light from the three primary colors (red, green blue) composed of seven kinds of shade by the composition of the spectrum. Color temperature of light is designed to measure the color of the ingredients.
Light color used to calculate the composition of the way, is the late 19th century by the British physicist Lord Kelvin ? created, he developed a set of color temperature calculation method, and its specific definition is based on the criteria of a blackbody radiation For the past issued by the wavelength.
Kelvin believes that the assumption that a Chunhei objects, can be landed on all of its heat absorption, but not losses, but also able to generate heat energy to all the "light" in the form of the release, it will be because of By the level of heat and a different color. For example, when black by the heat equivalent to 500-550 ℃, it will become dark red, a 1150 ℃ to 1050, will become yellow…… As a result, the color of light elements are related to the Asian people suffered the heat temperature Corresponding to. Only color temperature is Kelvin (° K, which is absolute temperature) units to the color temperature, rather than Celsius (℃) unit said. In the course of heated iron, black iron in the temperature gradually turns red, this is the best example of the trend of theory. When the Asian people by the heat so that it can produce the full spectrum of visible light waves, it changes from orange-yellow, yellow finally turned into white, usually used by the tungsten filament bulbs on the equivalent of the Asian people. Color temperature calculation method is based on the above principle, to use ° K said heating tungsten filament light emitted by the color temperature. According to this principle, any color temperature of light is the equivalent of the blackbody distributed by the same color by the "temperature."
Color is actually a psychological effect on the physical. All have the impression that color is the result of intermittent in the eyes of the spectrum on the response, the color temperature that is used to color the visual impression. Photography people know: only bright color, no-no color.
Color film of the design, according to the general is a true record of a particular color temperature of light to carry out the lighting, sunlight into 5500 ° K type, 3200 ° K-type lighting, and other. As a result, photographers must know how to use the same color temperature of light and colour film, will be accurate color reproduction. If the light color temperature and color temperature of the film each other imbalances, there would not be accurate color reduction. At this time, we must rely on filters to increase or decrease the light color temperature, exposure conditions and the development of the film to match color temperature, will have accurate color reproduction. And digital cameras, camcorders and other requirements of white balance adjustment, in fact that is the digital machines based on color temperature of the environment shooting location. Purpose is the same: In order to accurately reproduce colors.
How to conduct accurate color temperature positioning ? This requires the use of the "color temperature of"啦. Under normal circumstances, noon and 10:00 to 14:00, under cloudless skies, in the absence of direct light of the sun, sunlight about standards in 5200 ~ 5500 ° K. News photography lights in the color temperature 3200 ° K; general Tungsten Lamp, photo studio shooting black and white photographs of the Tungsten Lamp and the general use of the ordinary light bulb in the color temperature of about 2800 ° K; because of the low temperature, so in this Kinds of circumstances photographs Kuoyin out after the partial color will be yellow. And the general fluorescent color temperature in the 7200 ~ 8500 ° K around, so in fluorescent photos will be taken under the partial green. This is because the color temperature shooting environment settings of the machines and shooting the wrong color temperature. Kuo Yin-general can be adjusted. But if there are fluorescent lamps also filming the scene of a Tungsten Lamp, we become a hybrid source, this film it is very difficult to adjust.
To sum up, during the filming of the color temperature considerations, to set and adjust it is very important. Whether you are using traditional cameras or digital cameras and camcorders. Attention must be cool!
2. Spectrum
Polychromatic light spectrum is the dispersion systems (such as Prism, grating) by post, by Dan Seguang color spread of the wavelength (or frequency) followed with the size of the logo.
Light is the internal movement of atoms from the electronics. The atomic material internal e-campaign is different, so the light waves they emit are also different. The luminescence of different substances and absorb light, there are important theoretical and practical significance, has become a specialized disciplines - spectroscopy. Below a brief introduction about the spectrum of knowledge.
Spectroscope observation spectrum use spectroscope, here we Xianjiang the spectroscope tectonic theory. Figure 6-18 is the spectroscope Principle of the structure. It is from the parallel-A, prism P and B components of the telescope tube. A parallel light of the front of a slit width can be adjusted S, located in the focal plane of the lens L1 ① Department. Launched into the slit of light from the lens L1 refraction, a parallel light on the P prism She Dao. Different colors of light through the prism of different refraction along the direction fired, and L2 in the rear of the lens focal plane MN were gathered on a different color as the (line). B telescope tube through the eyepiece L3, to see the enlarged spectrum like. If the place where MN camera film, you can like perturbation of the spectrum. This device is called the spectral apparatus spectrograph.
Emission spectrometer luminous objects directly from the spectrum called emission spectrometer. There are two types of emission spectrum: continuous spectrum and surface wiring spectrum. Includes distribution of a row from here to various shade of red light spectrum called for spectroscopy (Wallpapers 6). Overheated solid, liquid and high-pressure gas emission spectrometer is the continuous spectrum. Electric Wire such as a light, heat the steel-have formed a continuous spectrum.
Not only contain some bright lines for the spectrum called the surface wiring spectroscopy (Wallpapers 7). Spectrum surface wiring in the line-called spectrum, corresponding to the lines of the different wavelengths of light. Rarefied gas or metal vapour emission spectrum is the surface wiring spectrum. Surface wiring spectrum is free from the state of the atomic emission, also called atomic spectrometry. Observation of the atomic spectrum of gas, you can use the spectrum of (6-19), it is a relatively small middle of a closed glass tube inside with low-pressure gas, the two ends of the two electrodes. The two electrodes from high voltage power supply, in the rarefied gas in the glow discharge, a certain color of light.
Observation of solid or liquid substances atomic spectra, they can put a gas flame or electric arc lights to burn in, so that they gasification after the luminous, you can see them from the spectroscope in the surface wiring spectrum.
Experiment proved that atoms different from the surface wiring launch spectrum are also different, each has a certain element of the atomic spectra of the surface wiring. Wallpapers 7 is the spectrum of several elements of the surface wiring. Each atom can only be issued with their own characteristics of certain wavelengths of light, so the surface wiring spectral characteristics of the spectrum called the atomic spectra. The characteristics of spectrum use of atomic material and can be identified on the atomic structure.
Absorption spectrum issued by the white high-temperature objects (which consists of a continuous distribution of all wavelengths of light) through the material, certain wavelengths of light are absorbed the material spectrum, called the absorption spectrum. For example, let a white arc lights through the lower the temperature of sodium gas (alcohol lamp in the Dengxin put on some salt, the salt will produce heat decomposition of sodium gas), and then use spectroscope to observe, you will see the continuous spectrum In the background there are two pay very close dark line (see Wallpapers 8. Spectroscope the resolving power is not high enough, can only see a dark line). This is the sodium atoms of the absorption spectrum. It is worth noting that the various atomic absorption spectrometry in a dark line Dugen each of the atomic emission spectroscopy in a corresponding surface wiring. This shows that low-temperature gas atomic absorption of light, this is precisely when the high temperature atoms in the light. Therefore, the absorption spectra of the spectrum (dark line), but also the characteristics of atomic spectra, is usually seen in the absorption spectrum of the characteristics of lines in the spectrum than the surface wiring less.