Photo-Aligned IPS LCD Alignment Layer for Uniform Display
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
IPS-TFT-LCDs face challenges in achieving uniform liquid crystal alignment over large areas due to stepped structures and sensitivity to initial alignment direction, leading to distorted images with decreased contrast ratio and uneven brightness, particularly due to limitations in conventional rubbing methods.
Innovation Solution
A liquid crystal display using a photo-reactive polyimide or polyamic acid alignment layer, irradiated with linearly polarized light, which provides stable and uniform alignment, reducing the thickness of the alignment layer to enhance transmittance and efficiency, and incorporating additional treatments like heating or infrared exposure to promote cross-linking and improve thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional rubbing method is used for alignment, then liquid crystal alignment capacity is achieved, but uniform alignment over large area is difficult and distorted images occur
Solution Approach 1:
The patent replaces the mechanical rubbing method with a photo-alignment method using polarized light. The alignment layer is irradiated with linearly polarized light to induce molecular orientation without mechanical contact, eliminating the distortion caused by rubbing cloth on stepped structures and enabling uniform alignment across large display areas.
Solution Approach 2:
The patent changes the alignment mechanism from mechanical shear force to optical field interaction. By controlling the polarization direction and intensity of incident light, the liquid crystal molecules are oriented uniformly across the entire display area, achieving precise control over alignment parameters without mechanical constraints.
2Manufacturing precision
If rubbing cloth is used for alignment treatment, then liquid crystal alignment is achieved, but alignment distortion occurs near stepped structures
Solution Approach 1:
The patent eliminates mechanical contact by using photo-alignment. Polarized light irradiation induces molecular orientation through optical fields, avoiding the physical distortion caused by rubbing cloth interacting with stepped electrode structures. This results in accurate and uniform alignment even near fine stepped features.
3Illumination intensity
If alignment layer thickness is reduced, then transmittance is improved, but alignment stability may be compromised
Solution Approach 1:
The patent optimizes the alignment layer thickness parameter to balance transmittance and alignment stability. By controlling the thickness within a specific range and using photo-alignment with controlled polarization parameters, the system achieves both high transmittance and stable molecular orientation without compromising either performance.
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 solution achieves high-quality images with improved contrast ratio and reduced afterimage issues, providing a more reliable and efficient alignment method that overcomes the limitations of conventional rubbing techniques.
Implementation Method 1
an alignment layer placed between the liquid crystal layer and at least one of the substrates, wherein the alignment layer is photo-reactive and comprises a photo-reactive polyimide or a photo-reactive polyimide and polyamic acid which is provided with a liquid crystal alignment capacity by being irradiated with light polarized essentially linearly
Implementation Method 2
A liquid crystal display generally works by applying an electrical field to liquid crystal molecules in a liquid crystal layer placed between a pair of substrates to change a direction of the molecules to which they are aligned and thereby change optical characteristics of the liquid crystal layer
Implementation Method 3
an IPS type display has been developed. It works on birefringence produced in the liquid crystal layer by its liquid crystal molecules rotating essentially in parallel to the substrate
Data Source
AI summary
It is an object to provide a liquid crystal display which reduces unsatisfactory display caused by distorted initial alignment direction in a liquid crystal alignment layer for IPS type displays, realizes stable liquid crystal alignment, is high in mass-productivity, and produces high-quality images of increased contrast ratio. The liquid crystal display contains alignment layers 109 placed between a pair of substrates 101 and 102, at least one of which is transparent, liquid crystal layer 110′ sealed between the alignment layers, common electrode 103 and source electrode 105 for applying an electrical field to the liquid crystal layer, thin-film transistors connected to each of these electrodes, polarizer plate 114 provided on at least one of the substrates, wherein at least one of the alignment layers 109 is composed of a photo-reactive polyimide and/or polyamic acid which can be provided with a liquid crystal alignment capacity by being irradiated with essentially linearly polarized light.