Liquid Crystal Composition for Wide Temperature Active Matrix Displays
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Solution Overview
Problem
Conventional liquid crystal compositions for active matrix elements face challenges in achieving a high higher limit temperature, low lower limit temperature, small viscosity, suitable optical anisotropy, low threshold voltage, and large specific resistance, which are essential for improving the performance and versatility of liquid crystal display elements.
Innovation Solution
A liquid crystal composition comprising specific compounds represented by formulas (1) to (5), with carefully optimized weight ratios, including a bicyclohexane compound that reduces viscosity and extends the lower limit temperature, combined with other compounds that enhance the higher limit temperature and dielectric anisotropy, to achieve a balanced set of characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a liquid crystal composition is designed to have a high higher limit temperature and low lower limit temperature, then the usable temperature range is widened, but the viscosity and response time characteristics become difficult to control
Solution Approach 1:
The patent uses a composite liquid crystal composition comprising multiple specific compounds (compounds of formula (1) to (5) with defined structural characteristics) to achieve both wide temperature range and controlled response characteristics. The composite nature of the composition allows simultaneous optimization of temperature range and viscosity properties that cannot be achieved with single compounds.
Solution Approach 2:
The patent carefully controls the weight ratios of different compounds in the composition to optimize the balance between temperature range and response time. By adjusting the parameters of composition (weight percentages of specific compounds), the invention achieves desired performance characteristics across a wide temperature range.
2Loss of time
If the viscosity of the composition is reduced to shorten response time, then the response time improves, but the higher limit temperature of the nematic phase decreases
Solution Approach 1:
The patent employs a composite composition where compounds of formula (2) (which have low viscosity and extend lower limit temperature) are combined with compounds of formula (3) (which have high higher limit temperature). This composite approach allows simultaneous achievement of short response time and high usable temperature range.
Solution Approach 2:
Different compounds in the composition are assigned different functional roles: compounds of formula (2) primarily reduce viscosity and extend lower limit temperature, while compounds of formula (3) primarily increase higher limit temperature. This local functional differentiation within the composition allows independent optimization of response time and temperature characteristics.
3Illumination intensity
If the optical anisotropy is optimized to maximize contrast ratio, then the contrast ratio improves, but the threshold voltage and specific resistance characteristics become compromised
Solution Approach 1:
The patent uses a composite composition comprising compounds of formula (4) and (5) which are specifically selected to provide suitable optical anisotropy (Δn) values while maintaining appropriate threshold voltage and specific resistance characteristics. The composite nature allows balancing of optical and electrical properties.
Solution Approach 2:
The patent optimizes the weight ratios of compounds in the composition to achieve the desired balance between optical anisotropy and electrical characteristics. By adjusting composition parameters, the invention achieves maximum contrast ratio while maintaining low threshold voltage and high specific resistance.
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 short response time, large voltage holding ratio, and suitable optical anisotropy, making it suitable for active matrix elements with improved performance across a wide temperature range.
Implementation Method 1
at least one compound selected from a group of compounds represented by formula (4) and formula (5) as a fourth component... compounds that enhance the higher limit temperature and dielectric anisotropy
Implementation Method 2
The optical anisotropy of the composition relates to the contrast ratio of the element. A product (Δn·d) of the optical anisotropy (Δn) of the composition and the cell gap (d) of the element is designed to be approximately 0.45 micrometers to maximize the contrast ratio
Data Source
AI summary
Liquid crystal compositions are provided having a high “higher limit temperature” of a nematic phase, a low “lower limit temperature” of a nematic phase, small viscosity, suitable optical anisotropy, low threshold voltage and large specific resistance. The composition includes at least one compound selected from a group of compounds represented by formula (1) as a first component, at least one compound selected from a group of compounds represented by formula (2) as a second component, at least one compound selected from a group of compounds represented by formula (3) as a third component, and at least one compound selected from a group of compounds represented by formulae (4) and (5) as a fourth component:wherein R1 is alkyl; R2 is alkenyl; R3 is alkyl or alkenyl; A1 and A2 are 1,4-phenylene, for example; Z1, Z2, and Z3 are a single bond, for example; Y1 and Y2 are fluorine, for example.