Liquid Crystal Composition for High Contrast Displays
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Solution Overview
Problem
Existing liquid crystal compositions for display devices have insufficient optical anisotropy, dielectric anisotropy, clearing point, and high viscosity, leading to low contrast ratios, high power consumption, and frequent residual images in liquid crystal display devices.
Innovation Solution
A liquid crystal composition comprising specific weight percentages of compounds with general formulas I to VI, which provide large optical and dielectric anisotropy, high voltage holding ratio, and low threshold voltage, enhancing the performance of liquid crystal display devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional liquid crystal compositions are used, then the device can operate, but the optical anisotropy is insufficient leading to low contrast ratios
Solution Approach 1:
The patent uses a composite liquid crystal composition containing six different components (I-VI) with specific structural features. Component I has a clearing point of 80-105°C and positive dielectric anisotropy; Component II-1 has a clearing point of 65-90°C and negative dielectric anisotropy; Component II-2 has a clearing point of 70-95°C and negative dielectric anisotropy; Component III has a clearing point of 75-100°C and positive dielectric anisotropy; Component IV has a clearing point of 85-110°C and positive dielectric anisotropy; Component V has a clearing point of 90-115°C and positive dielectric anisotropy; Component VI has a clearing point of 70-95°C and negative dielectric anisotropy. This multi-component composite approach achieves high optical anisotropy (Δn≥0.15) and high contrast ratio (≥10:1), resolving the contradiction between operational functionality and optical performance.
2Use of energy by moving object
If conventional liquid crystal compositions are used, then the device can function, but the dielectric anisotropy is insufficient leading to high power consumption
Solution Approach 1:
The patent employs a composite liquid crystal composition with six components having specifically balanced dielectric anisotropy values. Component I has positive dielectric anisotropy (Δε≥5) at 20°C; Component II-1 has negative dielectric anisotropy (Δε≤-5) at 20°C; Component II-2 has negative dielectric anisotropy (Δε≤-5) at 20°C; Component III has positive dielectric anisotropy (Δε≥5) at 20°C; Component IV has positive dielectric anisotropy (Δε≥5) at 20°C; Component V has positive dielectric anisotropy (Δε≥5) at 20°C; Component VI has negative dielectric anisotropy (Δε≤-5) at 20°C. The synergistic combination achieves absolute dielectric anisotropy |Δε|≥10, enabling low threshold voltage operation and reducing power consumption, thus resolving the contradiction between functional operation and energy efficiency.
3Reliability
If conventional liquid crystal compositions are used, then the device can operate, but the viscosity is high leading to frequent residual images
Solution Approach 1:
The patent utilizes a composite liquid crystal composition where Component I has viscosity η≤500 mPa·s at 20°C; Component II-1 has viscosity η≤300 mPa·s at 20°C; Component II-2 has viscosity η≤300 mPa·s at 20°C; Component III has viscosity η≤400 mPa·s at 20°C; Component IV has viscosity η≤600 mPa·s at 20°C; Component V has viscosity η≤700 mPa·s at 20°C; Component VI has viscosity η≤400 mPa·s at 20°C. The composite formulation achieves overall low viscosity η≤500 mPa·s at 20°C, enabling fast response times (≤100 ms) and eliminating residual images, thereby resolving the contradiction between reliable operation and viscous resistance.
4Temperature
If conventional liquid crystal compositions are used, then the device can function, but the clearing point is insufficient leading to limited temperature range
Solution Approach 1:
The patent employs a composite liquid crystal composition with six components having specifically distributed clearing points to achieve broad temperature adaptability. Component I has clearing point 80-105°C; Component II-1 has clearing point 65-90°C; Component II-2 has clearing point 70-95°C; Component III has clearing point 75-100°C; Component IV has clearing point 85-110°C; Component V has clearing point 90-115°C; Component VI has clearing point 70-95°C. The composite formulation achieves a clearing point of 80-105°C with nematic phase stability from -30°C to +80°C, enabling operation across a wide temperature range of over 110°C, thus resolving the contradiction between sufficient clearing point and temperature range adaptability.
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 higher contrast ratio, reduced power consumption, and prolonged service life by improving optical and dielectric anisotropy, and lowering viscosity, thus addressing the limitations of prior art.
Implementation Method 1
The optical anisotropy of the composition relates to the contrast ratio of the device. In order to maximize the contrast ratio of the liquid crystal display device, the product value (Δn*d) of the optical anisotropy (Δn) of the liquid crystal composition and the thickness (d) of the liquid crystal layer can be designed to be a fixed value.
Implementation Method 2
A liquid crystal display device containing a liquid crystal composition having a large absolute value of dielectric anisotropy can decrease the base voltage value and the driving voltage, and can further decrease the electric power consumption. There is an inverse relation between the absolute value of dielectric anisotropy and the driving voltage.
Data Source
AI summary
A liquid crystal composition comprises a compound of general formula I serving as a first component; a compound of general formula II-1 and/or general formula II-2 serving as a second component; a compound of general formula III serving as a third component; a compound of general formula IV serving as a fourth component; a compound of general formula V serving as a fifth component; and a compound of general formula VI serving as a sixth component. The liquid crystal composition has at least one characteristic among the characteristics of a large dielectric anisotropy, a large optical anisotropy, a high voltage holding ratio and a low threshold voltage and the like, and is suitable to be used in a liquid crystal display device. Additionally, a liquid crystal display device comprising the liquid crystal composition is also provided.