Auto Mixed Light Research for RGB LED Backlight Module

• Main Authors: Chung-Chih Hung, 洪崇智
• Other Authors: 張永農
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/26t9k7

碩士 === 國立虎尾科技大學 === 電機工程研究所 === 96 === In this thesis, light emitting diodes with red, green, and blue lights, respectively, are served as the back-light source and employed to generate the three primitive colors that can be adjusted and mixed to realize the output of white light. Attempts to bring out wider range of color space and obtain higher color saturation can, thus, be achieved. With the introduction of a half-bridge converter with power factor correcting function, an isolated-power-driven light-emitting diode is developed. By using the light-mixing and adjustment technique, the power saving and white light stabilizing can be accomplished. Through the experimental observations and quantitative measurements, the features of light-emitting diodes and photo-detectors are found to be susceptible to temperature. Moreover, different photo-detectors experience different degree of change of features for temperature fluctuation. To prevent the output white light from being experienced with color deviation due to temperature effect on the performance of LED, a mixed-light circuit module is developed, by integrating Programmable System on Chip with photo-diode sensor devices, to examine the ambient temperature and feedback voltage level of RGB photo-diodes. Through the usage of mixed-light control circuit module, the corresponding duty cycle of RGB LED can be adjusted, and the stable white light output can, consequently, be achieved. Furthermore, attempts to correct the error produced by photo-detector diode due to temperature are made by the introduction of a temperature sensor. A so-called “Mixed-light and adjustment control module corrector” was implemented to correct temperature modified value. By mixed-light and adjustment control module and calibrating of the corrector, the CIE1931 xy coordinates of output light are in good agreement with the predicted results.