Liquid Crystal Display Polymer Film Vertical Alignment
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Solution Overview
Problem
Liquid crystal display devices face issues with afterimage defects and complex production processes due to limitations in alignment layers, particularly the photo-alignment type's poor heat resistance and anchoring ability, and the need for self-aligning agents which can lead to non-uniform displays and increased costs.
Innovation Solution
A liquid crystal display device design featuring a substrate with an alignment layer and a liquid crystal composition containing a polymerizable compound that photopolymerizes with a self-aligning agent to form a polymer film, which vertically aligns liquid crystals and reduces afterimage defects by increasing the conversion ratio and residual amount of reactive mesogen during fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a photo-alignment type alignment layer is used to avoid dust particles and electrostatic residue, then the yield of fabrication is improved, but the heat resistance and ageing resistance become poorer and the ability to anchor liquid crystal molecules becomes weaker
Solution Approach 1:
The patent combines the photo-alignment layer and the self-aligning agent into a single integrated system. The self-aligning agent is incorporated into the liquid crystal composition, allowing it to work synergistically with the photo-alignment layer to achieve both high yield and reliable heat/ageing resistance.
Solution Approach 2:
The patent uses a composite liquid crystal composition containing the self-aligning agent (compound of formula I) combined with conventional liquid crystal compounds. This composite material provides enhanced performance by combining the alignment benefits of photo-alignment with the thermal stability and anchoring capability of the self-aligning agent.
2Device complexity
If the alignment layer is completely removed and self-aligning agent is added to the liquid crystal layer, then the preparation process is simplified, but non-uniform display and poor alignment of liquid crystal molecules occur and afterimage problem becomes serious
Solution Approach 1:
The patent introduces the self-aligning agent (compound of formula I) as an intermediary substance that mediates between the substrate and liquid crystal molecules. This compound provides the necessary alignment function that would otherwise require a separate alignment layer, while also preventing the afterimage problem through its specific molecular structure and properties.
3Device complexity
If a self-aligning agent is added to the liquid crystal layer for vertical alignment, then the alignment layer can be omitted, but the afterimage problem becomes serious due to reactive mesogen residue
Solution Approach 1:
The patent optimizes the chemical structure parameters of the self-aligning agent (compound of formula I) to reduce its reactivity while maintaining alignment functionality. By carefully designing the molecular structure with specific functional groups and chain lengths, the compound achieves effective vertical alignment with minimal residue formation, thereby reducing afterimage defects.
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 production efficiency, reduces afterimage defects, and improves display uniformity by forming a polymer film that prevents dust and electrostatic issues, while maintaining high charge retention and birefringence anisotropy.
Implementation Method 1
a polymerizable compound represented by Formula I... the liquid crystal composition comprises a liquid crystal compound, a self-aligning agent, and a polymerizable compound represented by Formula I
Data Source
AI summary
Provided is a liquid crystal display device comprising a first substrate, a second substrate, and a liquid crystal composition disposed between said first substrate and said second substrate, wherein a surface of said first substrate in contact with said liquid crystal composition is provided with an alignment layer, while said second substrate has no alignment layer; and said liquid crystal composition comprises a liquid crystal compound, a self-aligning agent, and a polymerizable compound represented by Formula I,