红、黄、绿、蓝led的正常工作电压,和电流（Normal working voltage and current of red, yellow, green and blue LED）

1、红、黄、绿、蓝led的正常工作电压,和电流（Normal working voltage and current of red, yellow, green and blue LED）Normal working voltage and current of red, yellow, green and blue LEDlight-emitting diodeLED (Light, Emitting, Diode) led is a solid state semiconductor device that converts electricity directly into light. T

2、he heart of LED is a semiconductor wafer, one end of which is attached to a bracket, one end is negative, and the other is connected to the positive electrode of the power to encapsulate the entire wafer with epoxy resin. Semiconductor wafers consist of two parts, one is P type semiconductor, in whi

3、ch the hole dominates, and the other end is N type semiconductor, which is mainly electronic here. But when the two semiconductors are connected, they form a P-N junction between them. When the current passes through the wire acting on the chip, the electrons are pushed into the P region. In the P r

4、egion, electrons combine with the hole and then emit energy in the form of photons, which is the principle of LED luminescence. The wavelength of light, that is, the color of light, is determined by the material that forms the P-N junction.50 years ago, people had already understood the basic knowle

5、dge that semiconductor materials can produce light. The first commercial diode was produced in 1960. LED is English light emitting diode (light emitting diode) abbreviation, its basic structure is an electroluminescentsemiconductor materials, placed on a wire rack, then sealed with epoxy resin aroun

6、d the solid package, so to protect the internal core function, so the seismic performance of LED good.The core part of the LED is a wafer consisting of type P semiconductors and type N semiconductors. There is a transition layer between the P type semiconductor and the N type semiconductor, called t

7、he p-n junction. In some PN junctions of semiconductor materials, the injected minority carriers combine with the majority carriers to release excess energy in the form of light, thereby converting the electric energy directly into light energy. PN junction plus reverse voltage, the minority carrier

8、 is difficult to inject, so it does not emit light. The diode, produced by injection electroluminescent principle, is called light-emitting diode, commonly known as LED. When it in a positive state of the work (which ends with forward voltage), the current flows from the LED anode cathode, semicondu

9、ctor crystals on the issue from the ultraviolet to infrared light of different colors light and the strength of the current.Initially, LED was used as an indicator light source for instruments and meters. Later, various light colored LED were widely used in traffic light and large area display scree

10、n, which produced very good economic and social benefits. Take the 12 inch red traffic light, for example, in the United States, which uses a long life, low light, 140 watt incandescent lamp as a source of light, producing 2000 lumens of white light. After the red filter, the light loss is 90%, leav

11、ing only 200 lumens of red light. In the new design of the lamp, Lumileds company uses 18 red LED light sources, including circuit loss, including a total power consumption of 14 watts, which can produce the same light effect. Automobile signal light is also an important field of LED light source ap

12、plications.For general lighting, people need white light sources more. In 1998, white light LED was successfully developed. The LED is fabricated by encapsulating GaN chips with yttrium aluminum garnet (YAG). GaN chips emit blue light (lambda p=465nm, Wd=30nm), sintered at high temperature, and Ce3+

13、 containing YAG phosphors emit yellow light after excitation by this blue light, with a peak value of 550nm. Blue chip installed in the LED based wanxingreflection in the cavity covered with a resin mixed with thin films of YAG, about 200-500nm. The blue light emitted by the LED substrate is absorbe

14、d by the phosphor, and the other part of the blue light is mixed with the yellow light emitted by the phosphor, so that the white light can be obtained. Now, for InGaN/YAG white LED, by changing the chemical composition of YAG phosphor and adjusting the thickness of phosphor layer, the white light o

15、f color temperature 3500-10000K can be obtained. The method of obtaining white light through blue light LED has the advantages of simple structure, low cost and high technical maturity, so the utility model has the most application.In the 60s of last century, scientific and technological workers dev

16、eloped LED LED using the principle of semiconductor pn junction light emitting. The LED was then made of GaASP, whose emitting color was red.After nearly 30 years of development, now we are very familiar with the LED, has been able to issue red, orange, yellow, green, blue and other colors. However,

17、 the white light LED required for illumination has only developed in recent years. Here we introduce the white light LED for illumination.1. the relation between the spectrum of visible light and LED white light. As far as we can see, the wavelength range of light spectrum is 380nm 760nm, which is t

18、he seven chromatic light that can be perceived by human eyes - red, orange, yellow, green, cyan, blue and purple, but each of the seven colors is a monochromatic light. For example, the peak wavelength of red light produced by LED is 565nm. In the visible light spectrum is not white light, because w

19、hite is not monochromatic light, but light composite by a variety of monochromatic light synthesis, as the sun light is composed of seven kinds of monochromatic and white light, white light color TV is composed of three primary colors of red, green and blue synthesis. Thus, to make LED emit white li

20、ght, its spectral characteristics should include the entire visible spectral range. But to manufacture this kind of LED, it is impossible under the present process condition. According to the research of visible light, the human eye can see white, mixed with at least two light, two light emitting wa

21、velength (blue light and yellow light emitting wavelength) or three (blue light + + red light green light) model. Blue light is needed for all two modes of white light, so the uptake of blue light has become the key technology for manufacturing white light, the Blu ray technology pursued by major LE

22、D manufacturers. The international master Blu ray only a handful of manufacturers, such as Japans Nichia, Japans TOYOTA synthesis, American CREE, German OSRAM, so white LED application, especially the high brightness white LED spread in China there is a process.2. white LED process structure and whi

23、te light source. For general illumination, the white light LED is usually formed in two ways on the process structure. The first is the use of blue light technology to match the phosphor to form white light; the second is a variety of monochromatic light mixing methods. Both of these two methods hav

24、e been successful in producing white light devices. The system shown in Figure 1 the first method to produce white light, blue light GaM chip LED map (lambda = 465nm, P) and YAG (yttrium aluminum garnet) phosphor package together, when a yellow light phosphor can be excited by blue light and the blu

25、e and yellow light mixed into white light (the the structure of LED as shown in Figure 2). The second method uses different colors of the chip to wrap together and produces white light by mixing each shade of light.Application foreground of 3. white light LED lighting new light source. In order to e

26、xplain the characteristics of white light LED, first look at the current situation of the lighting source. The incandescent lamp and halogen tungsten lamp have a luminous efficiency of 1224 lumens / watt, and the luminous efficiency of fluorescent lamp and HID lamp is 50120 lumens / watt. The white

27、LED: in 1998, light white LED is only 5 lumens per watt, to 1999 has reached 15 lumens per watt, this index is similar to general household incandescent lamps, and in 2000, light efficiency of white LED has reached 25 lumens per watt, the index and the tungsten halogen lamp is similar. Some companie

28、s predict that by 2005, LED light efficiency of 50 lumens / watt, by 2015, LED light efficiency is expected to reach 150200 lumens / watt. The current white LED then can be either training. Thus, the development of white LED writers using lighting sources, will become possible reality.Incandescent l

29、amps and halogen lamps for general lighting purposes although cheap, but the low light efficiency (wasted power consumption thermal effect lamp), short service life, maintenance workload, but if using white LED for lighting, not only high light efficiency, and long service life (more than 10000 hour

30、s of continuous work), almost no maintenance. At present, the German company Hella LED developed using white light aircraft reading a street lamp; the Australian capital Canberra has used the white LED lighting lamp; city traffic management in China is also white LED to replace the early order of tr

31、affic lights. It is foreseeable that in the near future, white light LED will enter the family to replace the existing lighting.LED light source with the use of low-voltage power supply, low energy consumption, strong applicability, high stability, fast response time, no pollution to environment, co

32、lor light etc., although the price is compared with the existing lighting equipment is expensive, it will inevitably existing lighting devices.LED features and advantagesThe intrinsic characteristics of LED determine that it is the ideal light source to replace the traditional light source, and it h

33、as a wide range of uses.Small volumeLED is basically a small chip that is encased in epoxy, so its very small and very light.Low power consumptionLED power consumption is very low, in general, the working voltage of LED is 2-3.6V. The operating current is 0.02-0.03A. That is to say, it consumes no m

34、ore than 0.1W.Long service lifeUnder proper current and voltage, LED can last up to 100 thousand hoursHigh brightness, low calorieenvironmental protectionLED is made of non-toxic material, unlike fluorescent lamps that contain mercury, which can cause pollution, and LED can be recycled.DurableLED is

35、 completely encapsulated in epoxy resin, which is stronger than light bulbs and fluorescent tubes. There is no loose part in the lamp, which makes LED easy to damage.Classification of LED1. according to the luminous color of the luminous tubeAccording to the luminous color of the luminous tube, it c

36、an be divided into red, orange, green (subdivided green yellow, standard green and pure green), blue light and so on. In addition, some LEDs contain chips of two or three colors.The light emitting diodes can be divided into four types: colored transparent, colorless transparent, colored scattering a

37、nd colorless scattering, according to the light emitting diode with or without scattering agent, colored or colorless. A scattering led and used as an indicator.2. according to the luminous characteristics of the luminous tubeAccording to the luminous characteristics of the luminous tube, the dividi

38、ng lamp, the square lamp, the rectangular surface, the luminous tube, the lateral tube, the surface mounting micro tube, etc. The circular lamp is divided into diameter 2mm, Phi 4.4mm, Phi 5mm, Phi 8mm, Phi 10mm and phi 20mm by diameter. Abroad, 3mm 1/4 is usually labeled as T-1, and 5mm is denoted

39、as T-1 (3/4), and 4.4mm is denoted as T-1.The intensity distribution of circular luminous intensity can be estimated by the half value angle.There are three kinds of distributions from luminous intensity angle profiles:(1) high directivity. Typically a pointed epoxy package, or a metal reflective ca

40、vity package with no scattering agent. The half value angle is 5 degrees to 20 degrees or less. The utility model has high directivity, can be used as a local illumination light source or combined with an optical detector to form an automatic detection system.(2) standard type. The utility model is

41、normally used as an indicator lamp, and the half value angle is 20 DEG to 45 deg.(3) scattering type. This is an indicator light with larger viewing angle, and the half value angle is 45 degrees to 90 degrees or more, and the amount of scattering agent is larger.3. according to the structure of LEDAccording to the structure of LED, there are all kinds of epoxy encapsulation, metal base, epoxy packaging, ceramic base, epoxy packaging and glass packaging structure.4. according to luminous intensity and working currentAccording to the luminou