The Research Of Wide Color Gamut And Self-adjusting LED Backlight

The technology of wide color gamut and self-adjusting LED backlight is up to the minute to the whole world , which also belongs to the"863"project . The technology will be mainly used in the field of LCD-TV , with the purpose of widening the color gamut and improving the contrast ratio of LCD-TV , meanwhile minimizing the energy it will consume .Through the devising of one unit of the LED backlight , the intention of this thesis is to find the problems and key technologyies , which may be encountered in the process of the devising of the LED backlight for large LCD-TV , with the hope of establishing the foudation for further research and development .The present situation in the whole world and technical superiority of the wide color gamut and self-adjusting LED backlight are described . The principle and characteristics of the LED are introduced . The theory of the light,vision and chroma is also presented , which is very important in the process of devising LED backlight . Optical calculation and software emulation are accomplished in this paper , the former is to calculate the amout of flux and energy for each color LED, considering the influence of the LCD-panel , optical films and temperature ; the latter is to determine the influence of the distance ,which between LEDs and optical films and between the LED-array units , to the brightness uniformity . In order to obtain stable and exact amount light output , LED driver circuit and color control circuit are also devised . Color control circuit can provide three channel PWM signals , whose duty will vary according to the brightness and color coordinate , for LED driver circuit .The combination of LED driver circuit and color control circuit not only can adjust the white color point ,but also makes the LED backlight self-adjusting become feasible . PMU makes the power supply system become very easy , just need only one channel power input . PMU can convert 24V to 5V , 20V and 29V , which are indispensable for entire system . In order to enhance the reliability and reduce the EMI of the system , heat dissipation and EMC are also designed .The process of establishing the demo unit of the LED backlight is under the guidence of the theory . The result of this paper not only has proved the veracity of the software emulation and the importance of the academic analysis ,but also has provided a foundation for further research and development of large LCD-TV .