Application of LED backlight for TV

LED is a light emitting diode (Light-Emitting-Diode), is a light emitting device made of compound semiconductor material. The basic principle of the utility model is different from that the bulb needs to work at a temperature higher than 3000 DEG C, and the utility model does not need to use a high voltage excitation electron beam as a fluorescent lamp. LED and electronic components generally the same, only 2 ~ 4V voltage at room temperature can be a normal driving, so its life is longer than the traditional light sources, up to 100 thousand hours or more (the foreign industrial products up to 30 thousand ~ 50 thousand hours). According to the wavelength of light, the LED light source can be divided into visible light LED (wavelength 450 ~ 680nm) and invisible (infrared) LED (wavelength range from 850 to 1550nm). TV with LED backlight using visible light LED, visible light can be divided into high brightness LED and general brightness LED. LED backlight technology beyond CCFL in the TV industry, LED as backlight LCD, compared with the traditional backlight technology, LED backlight has higher color gamut, good color, the color expressive force in CCFL backlight of liquid crystal display technology, color range problems play a very good role to compensate; LED the service life of 100 thousand hours. Even for 10 hours a day, also can be used continuously for 27 years, greatly extend the life of LCD TVs, so as to achieve the overwhelming superiority of plasma technology; brightness adjustment range, the realization of LED power control is very easy, unlike the CCFL minimum brightness has a threshold, therefore, whether in bright outdoor or full the black interior, users are very easy to adjust the brightness of display equipment to the most pleasant state. In addition to the advantages of energy saving, color gamut, LED backlight has many unique advantages. The traditional CCFL lamp flashing led to low frequency, dynamic scenes may produce a picture to beat, but the LED backlight can be flexibly adjusted light frequency, and the frequency is much higher than that of CCFL, so it can show the motion picture perfect. LED backlight can perform real-time color management, the red green and blue 3 color light independently, easy to precisely control the display color characteristics of the backlight can also adjust the white balance, while ensuring the overall contrast, when the user's computer and video source switching in DVD machine, can easily adjust the white balance in 9600K and 6500K. While not sacrificing brightness and contrast. LED is a kind of planar light source, the most basic light-emitting unit is 3 to 5mm side of the square, the package is easy to be combined together to become a fixed area of the surface light source, with a good brightness uniformity. If the backlight is used as the LCD TV, the required auxiliary optical components can be done very simply, the screen brightness uniformity is better. LED low voltage power supply, very safe, power supply module design is quite simple. LED light source does not produce any ray, no mercury and other toxic substances, is a green light source. Flat structure allows LED to have a solid internal structure, seismic performance is also very good. According to Displaybank data show that from 2006 to 2010 showed an average annual compound growth rate of LED sales of, LCD backlight with an average annual growth rate of LED sales will reach 31.5%. Current TV was optimistic about the market of LED backlight, there has been considerable industry LED backlight LCD TV commercial, but will these back light trichromatic completely mainstream technology, but also a lot of problems need to be solved, estimation needs to take several years to solve these problems.

LED backlight is still a problem LED backlight technology as many new technologies have many attractive advantages, but LED is to become the mainstream of large size TV backlight source, there is need to solve some technical difficulties. By contrast, it has been found that LED is at a disadvantage in terms of power consumption, in addition, there are problems of high cost and poor consistency. Compared with the same size CCFL backlight, LED high current power consumption. At present, the output flux of CCFL is in the range of 5000 ~ 7000lm, the output flux of the actual screen is higher than 300lm, and most of the LED backlight can not reach the target. In addition, back light of the same size, LED is 4 times the price of CCFL (see Table 2). For the current price competition in the TV market, so that some TV manufacturers to flinch, only SONY in order to image quality regardless of cost. Of course, with the maturity of the technology and production scale, the cost of LED backlight will gradually decline. Because the TV backlight needs high brightness, so the use must be above 1W high brightness LED, and the number of LED, also because of increased TV panel area greatly increased; in addition to color uniform hundreds of LED all need to strictly selected wavelength, is only LED cost is very high. When using LED and cooling fins and a cooling fan to solve the thermal effect of the cost of parts, RGB color Sensor also need to adjust the color of the LED, and the Sensor will detect the content of LED Sensing Algorithm back to the peripheral circuit and the cost, because a large number of high brightness LED, resulting in the increase of drive current is a big problem. So in terms of today's technology, LED backlight can be difficult to complete the low price. In addition, compared with CCFL, using LED as the backlight has white poor consistency problems. LED in the network design is more difficult than linear light source CCFL, need to consider the intensity of LED radiation attenuation. The use of LED backlight for a long time will produce color shift, the wavelength will vary with temperature, resulting in different colors. In addition, heat dissipation, uniformity of light source, as well as LED chip light-emitting efficiency is also the current LCD panel manufacturers