Optimization of the TFT-LCD Module Electrical Setting for Minimal Flicker by the Optical Feedback Algorithm and Taguchi Method

• Main Authors: Yi-Hsiu Man, 滿益秀
• Other Authors: 陳念波
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/56703198931289556568

碩士 === 元智大學 === 光電工程學系 === 100 === TFT-LCD (thin film transistor liquid crystal display) is ubiquitous on popular 3C products (computer, communications, and consumer-electronics). Regarding TFT-LCD manufacturing, flicker minimization is always one of the important items on the quality control list. Previous studies showed that flicker is closely related to Vcom (common voltage). An optimal Vcom setting suitable to the characteristic of the particular LCD can minimize flicker. One of the common practices in manufacturers, due to its low cost, is placing a VR (variable resistor) in the liquid crystal display module to adjust Vcom after assembled. The major drawback is that the adjustment often gets deviated and renders unqualified displays because of the VR’s quality and/or the shipping damage on VRs. Consequently, the yield gets degraded and the expense is wasted. Another way to set Vcom is finding its value during the circuit designing stage by sorting full-fledged optical measurement data from many LCD panel samples. This alternative method is not economical and cannot quickly handle the situation where the LCD panels from different lots have different characteristics than those previously sampled. In my study, the improvement on the latter method is made by applying Taguchi method to reduce the measurements and designing a quick and economical measurement apparatus. The new measurement apparatus is the application of trans-impedance amplifiers and photodiodes to make a photo sensor, and the custom-built algorithm “Auto trimming” to efficiently find the optimal value of Vcom for the minimal flicker. The novel method can greatly reduce the cost and the time needed to adjust Vcom for reduction of the flicker.