Study On The Improvement Of Image Sticking In TFT-LCD

The application of TFT-LCD is becoming more and more widely,and the requirement for performance of liquid crystal display is getting higher and higher.Wider viewing angle,higher contrast ratio,lower power consumption,and faster response time are main direction to improve the product performance.In addition,the demand for picture quality is getting more and more strict.The image sticking and mura are more important factors for the picture quality.Normally the image sticking will become serious with the extension of power on and start-up time.Solving the problem of image sticking has become a problem that TFT manufactures have to solve for a long time.We tested various conditions to find out the effect factors,to improve the issue of image sticking.There are two basic elements of the image sticking: the impurity ions and the DC offset voltage.In that case,impurity ions concentrated on TFT and CF will create DC offset voltage and image sticking in cell.There are many factors influencing the image stciking: product features,process condition,optics,materials and so on.In this paper,I explored the design of the optimization drive mode,process conditions,optics code and different material of cell to verify the best condition to solve the image sticking.By utilizing the 2nd source material for mass production,we successfully achieved the company's strategy and improvement of image sticking.The main study is as follow:1.The optimization of Pixel design: in order to reduce image sticking,TFT and CF commcom electrode ar eseparated to adjust the common voltage and gray correction.In addition,it is feasible to adjust the volatge of capacitors for VA products to slove the problem of image sticking.2.The adjustment of Panel driving: the driving voltage of gamma was adjusted to improve the problem of image sticking,and it has been introduced into the mass production.3.The processs conditions: in order to inhibite the separation of Si-H,Si-Si bond and the weak bond to dangling bond,I mainly explored the influnce of the structure and film quality of the silicon film.At the same time,the thickiness of the amorphous silicon residual film effect of the leakage current on the image sticking,which is optimized to avoid the diffusion of the P element,which causes the back-channel leakage current.4.The influence of mterials: I verrified the different liquid crystal and PI material which influence the precipitation of ionic impurities.The higher value of the voltage retention rate of the PI,the serious phenomenon of image sticking become,which is required above 98% at nomal temperature.By contrast,the higher ion density of liquid crystal material,the higher risk of image sticking will be.In this paper,the verification shows that the ?? and the polar moecules of A company is larger than B company,and the image sticking is better than revision Type liquid crystal.In the making of TFT,in order to reduce impuriy ions coming from stripper,material supplier usually cut down the types of additives.In this research,it was found that,it cannot remove impurities in the channel of device by this method.These impurities were oxidized by precoss of film-forming and etching,so which don't have condictivity.Therefore,the impurities form TFT making process,has not dirict influnce on image sticking.