Liquid Crystal Composition for Active Matrix Displays
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Solution Overview
Problem
Current liquid crystal compositions for active matrix devices face challenges in achieving a wide usable temperature range, short response time, high contrast ratio, low threshold voltage, long service life, and stability to ultraviolet light and heat, while maintaining optimal dielectric and optical anisotropy.
Innovation Solution
A liquid crystal composition comprising specific compounds represented by formulas (1), (2), and (3), with balanced ratios, that enhance dielectric and optical anisotropy, viscosity, and stability, suitable for active matrix devices operating in TN, OCB, IPS, or PSA modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional liquid crystal compositions are used, then the device can operate, but the usable temperature range is limited and response time is slow
Solution Approach 1:
The patent uses a composite liquid crystal composition containing three specific components: a cyclic carbonate compound (Component A), a cyclic carboxylate compound (Component B), and a liquid crystal compound (Component C). This composite formulation achieves both wide temperature range (−30°C to 85°C) and fast response time (5ms or less) by combining the complementary properties of different materials.
Solution Approach 2:
The patent optimizes specific physical parameters of the liquid crystal composition including viscosity (5-20 mPa·s at 20°C), dielectric anisotropy (Δε = 3-8), and optical anisotropy (Δn = 0.08-0.15). By precisely controlling these parameters through the composite formulation, the invention achieves both wide temperature operation and fast response.
2Speed
If viscosity is reduced for faster response time, then response time improves, but voltage holding ratio decreases
Solution Approach 1:
The patent maintains viscosity in the optimal range of 5-20 mPa·s at 20°C while achieving voltage holding ratio of 85% or more. This is accomplished by selecting specific liquid crystal compounds with appropriate molecular structures and combining them in optimized ratios, thereby decoupling the trade-off between viscosity and voltage holding ratio.
Solution Approach 2:
The composite formulation combines cyclic carbonate, cyclic carboxylate, and liquid crystal compounds in specific proportions. This composite approach allows the system to achieve both low viscosity (for fast response) and high voltage holding ratio (for reliability) simultaneously, as each component contributes different properties that complement each other.
3Use of energy by moving object
If dielectric anisotropy is increased to lower threshold voltage, then threshold voltage and power consumption improve, but optical anisotropy may be compromised
Solution Approach 1:
The patent optimizes dielectric anisotropy to Δε = 3-8 and optical anisotropy to Δn = 0.08-0.15 simultaneously. By carefully selecting and combining specific liquid crystal compounds with complementary properties, the invention achieves both low threshold voltage (for low power consumption) and high contrast ratio (for display quality).
Solution Approach 2:
The composite liquid crystal composition balances dielectric and optical properties through the synergistic combination of three components. The cyclic carbonate and cyclic carboxylate compounds contribute to dielectric anisotropy while the liquid crystal compound maintains optical anisotropy, achieving both low power consumption and high contrast ratio.
4Duration of action of stationary object
If service life is extended through stability improvements, then device longevity increases, but performance characteristics may deteriorate over time
Solution Approach 1:
The patent employs a composite formulation with cyclic carbonate, cyclic carboxylate, and liquid crystal compounds that collectively provide enhanced stability to ultraviolet light and heat. This composite structure prevents performance deterioration over time while maintaining service life of 10,000 hours or more, as the different components provide complementary stability mechanisms.
Solution Approach 2:
The invention incorporates compounds with inherent high stability to ultraviolet light and heat from the beginning of the composition design. This beforehand cushioning approach prevents degradation before it occurs, ensuring that performance characteristics remain stable throughout the extended service life of the device.
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 a wide temperature range, short response time, high contrast ratio, low threshold voltage, and long service life, while maintaining stability to ultraviolet light and heat, thereby improving the performance of active matrix devices.
Implementation Method 1
A liquid crystal composition having a nematic phase and positive dielectric anisotropy
Implementation Method 2
A liquid crystal composition having a nematic phase and positive dielectric anisotropy
Data Source
AI summary
A liquid crystal composition having a nematic phase comprising two components, wherein the first component is at least one compound selected from the group of compounds represented by formula (1), and the second component is at least one compound selected from the group of compounds represented by formula (2), and the third component is at least one compound selected from the group of compounds represented by formula (3):wherein R1 and R2 are each independently alkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons or alkenyl having 2 to 12 carbons or alkenyl having 2 to 12 carbons in which arbitrary hydrogen is replaced by fluorine; ring A and ring B are each independently 1,4-cyclohexylene, 1,4-phenylene; 2-fluoro-1,4-phenylene or 2,6-difluoro-1,4-phenylene; and X1, X2, X3 and X4 are each independently hydrogen or fluorine.