Research On Physical Compensation Method For Curved Liquid Crystal Panel

Curved TVs have been highly praised by many TV manufacturers for their outstanding perspective performance in recent years.Actually,curved TFT-LCD panels are formed by using external force from original flat LCD panels.However,internal structure of curved LCD panel will inevitably change,leading to a series of poor image problems.In this thesis,a series of researches were conducted on the improvement of display picture quality of 55-inch curved LCD TV products that were relatively popular in the market,the thicknesses of its glass substrates were 0.5mm and 0.7mm,respectively.Although different display technologies have developed rapidly,especially organic light emitting diode products have entered the market,the mainstream display products(about 90%)are still TFT-LCD products.In the thesis,the phenomenon and distribution regularities of misalignment between RGB pixels on the upper substrate and TFT arrays on the lower substrate were observed.The relationship between the change of misalignment and poor display quality of LCD screen was investigated through both of experiments and simulation.In order to solve the ununiform brightness and vertical crosstalk under specific display mode due to curved state of panel,a novel method of position pre-compensation of TFT device unit and BM widening were proposed.The novel method was verified in practical curved TFT-LCD products,and a set of design guidelines which had been productized was presented based on the method.Firstly,a design scheme of compensating TFT spacing offset on array substrates was proposed.In advance,offset compensation was made for the alignment relation between RGB pixels on the upper CF substrate and TFT cells on the array substrate to reduce the width of the dislocation area between RGB pixels and TFT cells caused by bending of the LCD panel.Secondly,the design method of BM broadening on the upper CF substrate was proposed.The width of BM on the upper CF substrate should be widened to cover part of the dislocation area between the upper and lower substrates and reduce the visible width of the dislocation area of the upper and lower substrates.In addition,the stress distribution inside changed with the radius of curvature due to curved glass substrate.When there was internal stress inside the glass,the amorphous glass exhibited birefringence characteristics,which would cause a phase difference when light propagated through the glass substrate,so that under the dark state,light leakage was easily observed near the corner where was suffered maximum stress.In order to solve the problem,an optimization method for the contour curve of the LCD glass substrate was presented.With the help of the method,internal stress inside LCD glass could be released,which significantly weakened the degree of light leakage of LCD display under dark display mode meeting the quality requirements of products.The achievements include:Firstly,according to the principle of birefringence caused by the stress of glass substrate,the stress distribution of 55-inch LCD after bending was analyzed,and the mechanism of light leakage in corners of curved LCD was clarified.Secondly,the composite contour design scheme of arc and tangent was proposed,which effectively alleviated the degree of light leakage in the corner of the LCD display under the bending state,and reduced the difficulty in actual processing and production.This thesis presented a reliable design method of curved LCD display,which may made a contribution to the technical development and quality improvement of curved TFT-LCD panels.