COA LCD Image Sticking via UV2A Alignment and Dielectric Control
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Solution Overview
Problem
COA type LCDs face issues with image sticking due to the deterioration of LC molecules caused by increased dielectric constant, leading to reduced voltage holding ratio and poor reliability.
Innovation Solution
A COA type LC panel is developed using a photo-alignment technology of ultraviolet induced multi-domain vertical alignment (UV2A) with alignment films made of polarized light-sensitive polyimide materials, incorporating a mixture of polar and non-polar LC monomers to control the dielectric constant of the LC molecules within a specific range, thereby improving image stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the dielectric constant of LC molecules is increased by increasing the proportion of polar LC monomer to enhance optical performances, then response time is improved, but the stability of LC molecules deteriorates leading to image sticking
Solution Approach 1:
The patent changes the chemical composition parameters of the LC mixture by incorporating specific non-polar monomers (cyclic carbonate compounds and/or cyclic carboxylate compounds) alongside polar monomers. This parameter adjustment optimizes the dielectric constant while maintaining molecular stability, preventing image sticking while preserving fast response time characteristics.
Solution Approach 2:
The patent creates a composite LC material system by combining multiple types of monomers (polar and non-polar) with specific functional groups. This composite approach allows the liquid crystal mixture to achieve both high dielectric constant for fast response and sufficient stability to prevent deterioration and image sticking during operation.
2Manufacturing precision
If UV2A photo-alignment technology is used to form alignment films, then alignment precision is improved, but manufacturing complexity increases
Solution Approach 1:
The patent replaces traditional mechanical rubbing alignment methods with UV2A photo-alignment technology. This substitution uses ultraviolet light irradiation to induce molecular orientation in the alignment layer, achieving superior alignment precision without the contact and wear issues of mechanical methods, though requiring additional photopolymerization process steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The controlled dielectric constant effectively reduces image sticking, enhancing the reliability of the COA type LCD by maintaining the alignment and stability of LC molecules, as demonstrated by improved voltage holding ratio and reduced image sticking issues.
Implementation Method 1
The first and second alignment films, which are made of a polarized light-sensitive material, are formed by a photo-alignment technology of an ultraviolet induced multi-domain vertical alignment (UV2A)
Data Source
AI summary
A color-filter-on-array (COA) type liquid crystal panel and a manufacturing method thereof are disclosed. An alignment film in the COA type liquid crystal panel is formed by a photo-alignment technology of an ultraviolet induced multi-domain vertical alignment (UV2A). Also, a problem of image sticking of an existing COA type liquid crystal display is improved by controlling the dielectric constant (Δε) of the liquid crystal molecules of a liquid crystal layer in the COA type liquid crystal panel.