Polymer-Stabilized Liquid Crystal Composition for Low Voltage Displays
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Solution Overview
Problem
Current polymer-stabilized liquid crystal display devices face issues with high driving voltage and tilt angle limitations, which affect their operational stability and display quality, particularly when using smectic liquid crystals for grayscale displays.
Innovation Solution
A polymer-stabilized liquid crystal composition combining a liquid crystalline polymer precursor and a non-liquid crystalline polymer precursor is used, with specific polymerizable compounds and chiral compounds to achieve a balance in anchoring force and glass transition temperature, reducing driving voltage and enhancing tilt angle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photocurable liquid crystalline monomer is added to stabilize alignment in a polymer-stabilized liquid crystal device, then alignment stability is improved, but the driving voltage increases
Solution Approach 1:
The patent changes the chemical structure parameters of the liquid crystalline monomer by introducing fluorine atoms at specific positions (using compounds with formulas (III-a) to (III-d) where R1-R6 are specific combinations of H, F, and alkyl groups). This structural modification adjusts the molecular properties to reduce the anchoring energy between the polymer and liquid crystal, thereby lowering the driving voltage while maintaining alignment stability.
Solution Approach 2:
The patent uses a composite system consisting of a polymer matrix formed from the photocurable liquid crystalline monomer combined with specific smectic liquid crystal compounds. The composite material properties are optimized by selecting monomers with specific fluorine-containing groups that create appropriate interfacial interactions, achieving both alignment stabilization and reduced driving voltage.
2Reliability
If a liquid crystalline monomer is added to a smectic liquid crystal, then alignment is stabilized by polymer formation, but the tilt angle is reduced
Solution Approach 1:
The patent modifies the molecular parameters of the liquid crystalline monomer by incorporating specific fluorine-containing groups (formulas (III-a) to (III-d)) that adjust the steric and electronic properties. This changes the interaction strength between the polymer network and liquid crystal molecules, allowing sufficient anchoring for stability while preserving the tilt angle necessary for smectic phase functionality.
Solution Approach 2:
The patent introduces fluorine atoms at specific local positions in the molecular structure (R1-R6 positions in the general formulas) to create localized regions with specific electronic and steric properties. This local modification allows the polymer to anchor effectively at the interface while leaving the bulk liquid crystal tilt angle unaffected.
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 composition results in a liquid crystal display device with low driving voltage, stable thermal and dynamic performance, and improved contrast, enabling effective grayscale displays across a wide temperature range.
Implementation Method 1
a technique is disclosed in which a photocurable monomer is added to a twisted nematic liquid crystal, followed by light irradiation in an attempt in polymer-stabilization of alignment
Implementation Method 2
Examples disclose voltage-dielectric constant characteristics when the concentration of the liquid crystalline monomer is varied
Implementation Method 3
a technique of applying for an OCB (optically compensated birefringence) mode
Data Source
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AI summary
An object of the present invention is to obtain a polymer-stabilized liquid crystal composition which can suppress dependency of a driving voltage on a temperature by decreasing the driving voltage. To a low-molecular liquid crystal compound, a chiral compound, and a specific acrylate and a polymerizable liquid crystal compound as polymerizable acrylate compounds are added, to prepare a polymer-stabilized liquid crystal composition. By subjecting the polymer-stabilized liquid crystal composition to ultraviolet exposure while maintaining a desired alignment state to form a polymer chain in a liquid crystal phase, a polymer-stabilized liquid crystal display device containing a low-molecular liquid crystal in a stabilized alignment state is obtained.