Study On The Improvement Of Liquid Crystal Light Alignment Dark Lines

The alignment method used in the TFT-LCD manufacturing process of LCD Optoelectronics is not the friction alignment commonly used in the industry,but the unique patented HVA(Huaxing Vertical Alignment)technology of Shenzhen H Optoelectronics Company(hereinafter referred to as H Company).Its technical feature is to use the original liquid crystal molecules to add a small amount of polymer monomers(Monomer),after the completion of the box forming process,through a special process of applying voltage and irradiating UV light,so that the active monomer molecules are on the surface of the polyimide film.Polymerize into a polymer layer.The function of this polymer layer is similar to the miniature traditional protrusions(Protrusions),but it does not reduce the aperture ratio and can provide the required pretilt angle.Research significance:Because H Company’s optical alignment technology started late,and the technologies of Korean and Japanese manufacturers are kept secret,with the continuous development of high-end products of LCD Optoelectronics,some of the original improvement technical methods are no longer suitable for increasingly high-end product design and produce.This research topic focuses on the improvement of the problem of liquid crystal light alignment dark lines that occurred during the development and mass production of H company’s new model,to improve the yield and competitiveness of the product,reduce the company’s cost,and increase the company’s profit.The dark lines of the liquid crystal optical alignment are that the liquid crystal molecules in a part or the entire surface are not arranged in a designed manner,that is,the required pretilt angle is not formed.Observing at the microscopic level,dark lines will appear in the middle of the pixels.Conventional dark lines are mainly caused by polyimide film(PI)coating film thickness,liquid crystal contamination,process interval time(Q Time),alignment debugging lead(Curing pad),and electrostatic discharge(Electro-Static discharge,ESD).Short circuit and other factors are related,and the objects of this research are mainly voltage,stress,and electrostatic optical alignment dark lines that are more challenging and difficult.The main results of this research are as follows:1)Voltage-type dark lines,a.For 49-inch ultra high definition display(Ultra high definition display,UD)product design and dark line film product design,the frequency of alternating current(AC)is reduced to 5HZ to improve the capacitance resistance due to product design The problem of dark lines bursting caused by too large RC Delay;b.43-inch LOC((laser cut on CF))designed products are due to the color filter(Color Filter,CF)side direct current(DC))Curing,the experiment has occurred in the thin film transistor(Thin Film Transistor,TFT)side of the ITO critical dimension(Critical Dimension,CD)subtle changes will interfere with the alignment electric field of the liquid crystal molecules,through the TFT array(Array)ITO process control and HVA parameters to broaden the ITO Margin.2)Stress dark lines,in order to solve the problem that the Three-TFT(3T)design of the 55-inch UD product is sensitive to the stress of the machine end,the new parameters of the Array common electrode(A-COM)are found through experimentation and planning to solve the problem The stress abnormality caused by the grounding of the A-COM on the TFT side has been applied and improved in many models.3)Electrostatic dark lines,because the production process environment cannot ensure that each position of the substrate achieves the best electrostatic condition.Through analysis and improvement experiments,the slow-climbing HVA parameters are found to solve the static dark lines and broaden the process margin.