Improving the feed-through effect for TFT liquid crystal displays

• Main Authors: Galong Lin, 林家榮
• Other Authors: none
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/31689370808145699394

碩士 === 逢甲大學 === 資訊電機工程碩士在職專班 === 93 === This thesis deals with the feed-through effect in TFT LCDs (Thin Film Transistor Liquid Crystal Displays).Several techniques have been proposed to compensate the difference in the rms (root mean square) voltages in the positive and negative voltages frames for the LCD. The flicker phenomenon during in displaying caused from the feed-through effect can also be improved. However, the capacitance of the LCD cell CLC, depends on the exerted voltage and is not constant for different gray level. A simple fixed offset voltage added in VCOM could not totally compensate the feed-through voltage . In this thesis, the TFT LCD with CS on Common structure was considered in the design of the driver circuit. The induce feed-through voltage △VP and it’s compensation were analyzed. In this study, it was found the driver circuit improved the portion of fine turning the gamma voltage for each gray level. For each gamma voltage, the corresponding VCOM was alternately polarized in each frame. In this study, there were 16 gray levels for up to 4096 colors for display. By use of a photodiode the feed-through caused flicker was observed and analyzed . The performances with uncompensated and compensate VCOM will be compared.