TFT-LCD公共电压耦合畸变的影响因素及与线残像关系的研究

摘要

In order to solve the line image sticking issue of TFT-LCD,the data of coupling voltage be-tween the data lines and the common electrode as well as the influencing factors were studied.By using metal welding technology,the common voltage(Vcom)distortion induced by signal voltage was measured and compared with the severity of the line image sticking.At the same time,the different influencing factors such as the mask design,the amplitude and frame change frequency of the signal, the TFT process and the adjustment of the film characters were studied respectively.The results showed that the change of the stray capacitance between the data lines and common electrode caused the Vcomdistortion,which is corresponding to the line image sticking.Altering the permittivity or di-mensions of the amorphous silicon layer can decrease the stray capacitance(including the overlap ca-pacitance between the data lines and common voltage lines,and the side capacitance between the data lines and the common electrode within the pixels),so the Vcomdistortion can be lowered and the line image sticking improved.Among the solutions,rising the frame change frequency or irradiating the amorphous silicon layer with UV have the best results,which the Vcomdistortions were fallen down by 55% and 62%,and the gray level that the line image sticking vanished was turned down from L127 to below L127.The research achievements could be the important guide and reference to the new TFT-LCD with large size,high resolution,high brightness and low power consumption.%为了解决TFT-LCD的线残像不良,对信号线与公共电极之间的电压耦合的大小和影响因素进行了研究.利用金属熔接技术,测量了屏内公共电极电压在信号线电压作用下发生的耦合畸变的大小,并将其与线残像的严重程度进行了对比.同时通过对不同的影响因素,即版图设计、信号线电压及反转方式、TFT工艺流程、TFT膜质调整分别进行了研究和测试.结果显示信号线和公共电极及绝缘层构成了MIS结构的电容,电容容值的变化导致的公共电压耦合程度与线残像的严重程度呈现明显的对应关系.通过改变非晶硅半导体层的介电常数或者尺寸设计,可以减小信号线与公共电极间的寄生电容(包括信号线金属与公共电极线金属的交叠电容和信号线与像素公共电极间的侧向电容),降低公共电极电压的耦合程度,改善线残像不良.其中提高信号电压转换频率和用紫外光照射半导体层的改善效果最为明显,耦合电压分别下降了55%和62%,线残像的消失灰阶从L172或更高转变为低于L127.研究成果对于大尺寸、高分辨率、高亮度、低功耗的TFT-LCD产品的设计和性能改善,有着重要的指导和参考意义.