Photoaligned Liquid Crystal Mixture Eliminates Polyimide Alignment Layers
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Solution Overview
Problem
Conventional liquid crystal display (LCD) manufacturing methods require polyimide alignment layers, which are costly and prone to issues like mura, contamination, and static discharge, and do not allow for the elimination of polyimide use while maintaining the advantages of IPS technology such as short response times and good viewing-angle dependence.
Innovation Solution
A method involving a liquid crystal mixture with self-assembling photoalignment agents and polymerisable compounds, where the mixture is photoaligned using linearly polarised light and then cured with UV light to achieve homogeneous alignment within the LCD, eliminating the need for polyimide layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyimide alignment layers are used in conventional LCD manufacturing, then liquid crystal alignment is achieved, but production cost increases and issues like mura, contamination, and static discharge occur
Solution Approach 1:
The patent removes the polyimide alignment layer from the LCD structure entirely, extracting the problematic component that causes mura, contamination, and static discharge. The invention achieves alignment functionality through a different mechanism using photoaligning agents directly in the liquid crystal mixture, eliminating the need for separate alignment layers.
Solution Approach 2:
The patent replaces the mechanical rubbing process used with polyimide layers with a photochemical alignment mechanism. Photoaligning agents in the liquid crystal mixture are activated by light irradiation to create alignment patterns, substituting mechanical contact-based alignment with optical-field-based alignment that avoids contamination and static discharge issues.
2Reliability
If polyimide alignment layers are used, then liquid crystal alignment is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the alignment function with the liquid crystal mixture itself by incorporating photoaligning agents directly into the LC mixture. This combines what were previously separate components (alignment layer and liquid crystal) into a single integrated system, simplifying the overall structure and manufacturing process.
Solution Approach 2:
The patent eliminates the polyimide alignment layer and associated rubbing equipment from the manufacturing process. By using photoaligning agents within the liquid crystal mixture that can be aligned through light irradiation, the invention removes the complex mechanical alignment apparatus and multi-step coating processes required for polyimide layers.
3Ease of manufacture
If photoaligning agents and polymerisable compounds are used together, then homogeneous alignment is achieved and polyimide is eliminated, but the liquid crystal mixture composition becomes more complex
Solution Approach 1:
The patent modifies the chemical composition parameters of the liquid crystal mixture by adding photoaligning agents and polymerisable compounds. These compositional changes enable the mixture to self-align through photochemical reactions when irradiated, providing alignment functionality without requiring separate polyimide layers or mechanical rubbing processes.
Solution Approach 2:
The patent creates a composite liquid crystal system by combining photoaligning agents, polymerisable compounds, and liquid crystal molecules into a single functional mixture. This composite material integrates multiple functions (alignment, structural integrity, electro-optical properties) within one unified composition, simplifying manufacturing despite the increased molecular complexity.
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 method simplifies the production process, reduces costs, and maintains the benefits of IPS technology by achieving stable and irreversible homogeneous alignment of liquid crystals, improving image quality and reducing production complexities.
Implementation Method 1
a self assembling photoalignment agent... self-assembling photoalignment agents... The liquid crystal mixture comprises... one or more self assembling photoalignment agents
Implementation Method 2
irradiating the liquid crystal mixture with linearly polarised light causing photoalignment of the liquid crystal mixture
Implementation Method 3
curing the polymerisable compound by irradiation with ultraviolet light causing fixation of alignment
Data Source
AI summary
The invention relates to a method of manufacturing a liquid crystal display device wherein a liquid crystal mixture having positive dielectric anisotropy or negative dielectric anisotropy is interposed between a first substrate and a second substrate, the liquid crystal mixture comprising liquid crystal molecules, a self assembling photoalignment agent, a polymerisable compound, and wherein said LC mixture is photoaligned by irradiation with linearly polarised ultraviolet light and then cured by irradiation with ultraviolet light.