TFT-LCD中像素电极耦合电容对显示画质的影响

Influence of pixel electrode coupling capacitance on the display quality in TFT-LCD

研究了TFT-LCD中像素电极与数据线之间的耦合电容(C_(pd))对显示画质的影响,分析了像素电极发生偏移后显示面板产生横纹不良的机理。研究结果表明,像素电极发生偏移后,数据线与左右两侧像素电极之间的C_(pd)耦合电容大小产生差异,造成相邻行间的像素发生不同方向的电压跳变。实际观察结果显示,当两行像素的亮度差异大于8个灰阶时,即会出现明显可见的横纹不良。提出了一种横纹不良改善方案,通过增加像素电极跨越数据线的条状设计结构,利用二者之间的交叠电容变化来补偿耦合电容的变化。模拟结果显示,当像素电极偏移1.2μm时,相邻行像素的亮度差异为6个灰阶,无水平横纹不良的产生。新型像素结构的开口率无损失,充电率满足产品设计要求,表明此方案可应用于产品设计中。

The influence of the coupling capacitance(Cpd)between the pixel electrodes and data line on the display quality in TFT-LCD was researched and the mechanism of the horizontal stripes Mura after the pixel electrode shifted was analyzed.The results show that the Cpdcoupling capacitance between the data line and pixel electrodes distributed on both sides are different which cause voltage hopping in different directions between pixels in adjacent rows when the pixel electrodes are offset.According to the actual observation,the visible horizontal stripes Mura appears when the different brightness between adjacent lines is greater than 8 gray scales.An improved method has been proposed by increasing the strip-shaped structure of the pixel electrodes crossed the data line and the overlap capacitance is used to compensate for the change of the coupling capacitance.The simulated results show that when the pixel electrode is shifted by 1.2μm,the difference in luminance between adjacent rows of pixels is 6 gray scales and there is no horizontal stripes Mura.The aperture ratio of the new pixel is unchanged and the charging ratio satisfies the product design requirement,indicating that this solution can be applied to product design.