Photo-Aligned LCD Alignment Layer Reducing Afterimages
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Solution Overview
Problem
Current liquid crystal displays (LCDs) face issues with afterimages and spots due to the limitations of existing alignment layers, which affect the stability and display quality.
Innovation Solution
The use of a vertical photo-alignment material with a photo-reactive diamine group and a major alignment material without a photo-reactive group, forming an alignment layer that increases in molar concentration ratio towards the surface adjacent to the liquid crystal layer, and is processed using ultraviolet rays without a rubbing process, reducing afterimages and spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional alignment layer is used, then the liquid crystal molecules can be aligned, but afterimages and spots occur reducing display quality
Solution Approach 1:
The alignment layer uses a composite material comprising a polyimide compound and a cyclic carboxylic acid compound. The polyimide provides baseline alignment functionality while the cyclic carboxylic acid compound (with specific structural features including a carbonyl group and aromatic ring) suppresses afterimages and spots through its unique molecular structure and interaction with liquid crystal molecules.
Solution Approach 2:
The invention changes the chemical composition parameters of the alignment layer by specifying precise compositional ratios: the cyclic carboxylic acid compound content is controlled at 1-50 wt% of the total alignment layer, with further optimization at 5-30 wt%. This parameter control optimizes both alignment performance and suppression of display defects.
2Ease of manufacture
If a rubbing process is used to form the alignment layer, then liquid crystal alignment is achieved, but production complexity and cost increase
Solution Approach 1:
The invention replaces the mechanical rubbing process with a chemical solution-based approach. The alignment layer is formed by coating a solution containing the polyimide compound and cyclic carboxylic acid compound, followed by heating treatment. This substitution eliminates the need for mechanical contact and complex rubbing equipment while achieving superior alignment uniformity and reducing production complexity.
3Stability of the object's composition
If the alignment layer composition is optimized for stability, then afterimages are reduced, but material selection becomes more complex
Solution Approach 1:
The invention applies local quality by specifying particular structural requirements for the cyclic carboxylic acid compound: it must contain a carbonyl group (C=O) and an aromatic ring structure with specific bonding characteristics. These localized structural features provide the stability needed to reduce afterimages while maintaining reasonable material selection flexibility within defined chemical families.
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
This approach enhances the stability and reduces afterimages and spots in LCDs, improving display quality and reducing production costs by eliminating the need for a rubbing process.
Implementation Method 1
the alignment layer including a vertical photo-alignment material which includes a first vertical functional group and a photo-reactive group
Data Source
AI summary
A liquid crystal display including: a first substrate and a second substrate facing each other; an alignment layer disposed on one of the first substrate and the second substrate and including a vertical photo-alignment material which includes a first vertical functional group and a photo-reactive group, and a major alignment material which does not include the photo-reactive group; and a liquid crystal layer disposed between the first substrate and the second substrate, wherein a ratio of a molar concentration of the vertical photo-alignment material to the molar concentration of the major alignment material increases in a direction towards a surface of the alignment layer adjacent to the liquid crystal layer.