Analysis And Solution Of Image Sticking Problem In TFT-LCD For Mobile Phone

LCD panels are known for their miniature size,portability,low radiation,low power consumption and their exceptional reliability.They are widely used in portable electronic devices,such as smart phones,tablets,laptop-computers,etc.In recent years,people have been demanding LCD products that are capable of better performances,which include higher resolution,higher response sensitivity,designs for eye comfort and so on.Among all the technical barriers,the image sticking is a major problem limiting the quality of TFT-LCD.Based on cases investigated in the fields where applications of LTPS(low temperature polycrystalline silicon)thin film transistor liquid crystal display are most common,this paper establishes the bases of 'image sticking' detection and identification,moreover,analyses the causes and offers solutions to the problem.A method,by customer's spec,where data measurement is combined with optical observation,is established:First,display 8x8 checkerboard static patterns on products for 1 hour.Second,swap the patterns displayed to 128-shade-gray-scale images directly.Lastly,as long as the images 'sticking' disappear within 3 minutes,the products are deemed 'accepts'.Otherwise,'defects'.The main conclusions are as follows:1.In theory,the two main factors contributing to 'image sticking' are,?foreign ion interference,and ? driver module voltage abnormality.While during the experiments conducted,the interference of foreign ions was ruled out for consideration in advance,with a series of practices of deterioration experiments.2.After combining the research findings and further analyses of the 'defects',we conclude that fine-tuning the white state voltage and VGH voltage can effectively reduce the chances of 'image sticking' occurring.By comparing the changes taking place when altering the TFT-LCD threshold voltage(Vth),raw material,voltage transfer curve,DC test condition and so on,we see the largest decreases in percentage figure for 'image sticking defects' by adjusting the threshold voltage(Vth).The above findings have been materialized in real production,where 'image sticking' problems occurring in mobile telephone screens have been effectively resolved,improving the overall quality of the products.