Liquid Crystal Composition for Fast Response VA Displays
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Solution Overview
Problem
Liquid crystal compositions for high-speed response displays, such as televisions, face challenges in achieving low viscosity, low rotational viscosity, and high elastic constant while maintaining refractive index anisotropy and nematic phase-isotropic liquid phase transition temperature, which are not adequately addressed by existing compositions.
Innovation Solution
A liquid crystal composition combining fluorobenzene derivatives with a 1-propenyl group and specific liquid crystal compounds having negative dielectric anisotropy, optimizing the content and structure to achieve low viscosity and high elastic constant without compromising refractive index anisotropy and transition temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If liquid crystal compounds with substantially zero Δ∈ (compounds C and D) are used to achieve low refractive index anisotropy, then the refractive index anisotropy is reduced, but the viscosity is not sufficiently decreased
Solution Approach 1:
The patent changes the chemical structure parameters of the liquid crystal compounds by introducing fluorobenzene derivatives with 1-propenyl groups, which have substantially zero Δ∈. This structural modification allows achieving low refractive index anisotropy while the specific molecular structure also contributes to reduced viscosity through improved molecular packing and reduced intermolecular interactions.
Solution Approach 2:
The patent creates a composite liquid crystal composition by combining multiple compounds with different properties: fluorobenzene derivatives with 1-propenyl groups (providing low Δn and negative Δ∈), and other liquid crystal compounds (providing appropriate viscosity and stability). This composite approach allows simultaneous optimization of refractive index anisotropy and viscosity that cannot be achieved with single compounds.
2Speed
If liquid crystal compound F is added to improve response speed, then the response speed increases, but the refractive index anisotropy and transition temperature may be compromised
Solution Approach 1:
The patent applies local quality by selecting specific fluorobenzene derivatives with 1-propenyl groups that have substantially zero Δ∈. These compounds are strategically chosen to provide localized improvements in response speed through their specific molecular structure and properties, while the overall composition is formulated to maintain the required refractive index anisotropy through the combined effect of multiple components.
Solution Approach 2:
The patent changes the physical parameters of the liquid crystal composition by incorporating compounds with specific molecular structures (fluorobenzene derivatives with 1-propenyl groups). These structural changes result in modified physical properties including reduced viscosity, improved response speed, and maintained refractive index anisotropy through the synergistic effect of the composite composition.
3Speed
If liquid crystal compound G and compound F are combined to achieve higher response speed, then the response speed improves, but the composition complexity increases and may affect manufacturing
Solution Approach 1:
The patent applies universality by using fluorobenzene derivatives with 1-propenyl groups that serve multiple functions simultaneously: they provide substantially zero Δ∈ for low refractive index anisotropy, contribute to negative Δ∈ for fast response, and offer appropriate viscosity characteristics. This multi-functionality reduces the need for multiple separate additives, thereby simplifying the overall composition while achieving high response speed.
4Illumination intensity
If compound with formula (I) is used to achieve low refractive index anisotropy, then the refractive index anisotropy is reduced, but the viscosity becomes considerably high
Solution Approach 1:
The patent changes the chemical structure parameters by using fluorobenzene derivatives with 1-propenyl groups instead of compounds with formula (I). This structural modification maintains the substantially zero Δ∈ property for low refractive index anisotropy while the fluorobenzene structure with 1-propenyl group provides better viscosity characteristics through reduced molecular polarity and improved molecular mobility.
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 achieves low viscosity and high elastic constant, resulting in a liquid crystal display device with high display quality and response speed, particularly suitable for VA mode and other active matrix driving applications.
Implementation Method 1
a liquid crystal composition having negative dielectric anisotropy (Δ∈) and is useful as a liquid crystal display material
Implementation Method 2
the refractive index anisotropy (Δn) and the nematic phase-isotropic liquid phase transition temperature (Tni) are not decreased
Data Source
AI summary
There is provided a liquid crystal composition having a sufficiently low viscosity (η), a sufficiently low rotational viscosity (γ1), a high elastic constant (K33), and negative Δ∈ with a high absolute value without decreasing the refractive index anisotropy (Δn) and the nematic phase-isotropic liquid phase transition temperature (Tni); and a liquid crystal display device with a VA mode or the like that uses the liquid crystal composition and has high display quality and high response speed. The liquid crystal display device that uses the liquid crystal composition of the present invention has a distinguished feature of high-speed response and is particularly useful as an active matrix driving liquid crystal display device. The liquid crystal display device is applicable to a VA mode, PSVA mode, PSA mode, IPS mode, or ECB mode liquid crystal display device.