Liquid Crystal Composition for Low Flicker and Fast Response
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Solution Overview
Problem
Liquid crystal display devices face challenges in achieving a short response time, large voltage holding ratio, low threshold voltage, high contrast ratio, long service life, and low flicker rate, particularly in maintaining stability to ultraviolet light and heat while optimizing dielectric anisotropy and viscosity for various operating modes.
Innovation Solution
A liquid crystal display device incorporating a composition with positive dielectric anisotropy, featuring a specific blend of compounds represented by formulas (1), (2), and (3), which are mixed in specific weight ratios to optimize the nematic phase temperature range, viscosity, optical anisotropy, and dielectric properties, and optionally including additives for enhanced stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a liquid crystal composition is designed to have positive dielectric anisotropy for AM devices, then the threshold voltage and power consumption are reduced, but the flicker rate increases
Solution Approach 1:
The patent applies parameter changes by carefully adjusting the dielectric anisotropy value to a specific range (0.5 to 2.0) and controlling the viscosity within a defined range (5 to 20 mPa·s at 20°C). By optimizing these physical parameters of the liquid crystal composition, the invention achieves both low power consumption and low flicker rate, resolving the contradiction between energy efficiency and display stability.
Solution Approach 2:
The patent employs composite materials by formulating a liquid crystal composition consisting of multiple components including nematic liquid crystal compounds, chiral compounds, and additives. This composite approach allows balancing the dielectric anisotropy and viscosity properties to simultaneously achieve low threshold voltage, low power consumption, and minimal flicker effect in the display device.
2Speed
If the viscosity of the liquid crystal composition is reduced to achieve short response time, then the response time improves, but the voltage holding ratio decreases
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the viscosity parameter within the range of 5 to 20 mPa·s at 20°C and adjusting the dielectric anisotropy to 0.5 to 2.0. This optimized parameter combination ensures that the liquid crystal molecules can respond quickly to voltage changes (short response time) while maintaining sufficient charge retention capability (voltage holding ratio above 90%).
3Illumination intensity
If the elastic constant of the liquid crystal composition is increased to improve contrast ratio, then the contrast ratio increases, but the response time increases
Solution Approach 1:
The patent resolves this contradiction by optimizing the elastic constant within a specific range that balances optical performance and response speed. By carefully selecting liquid crystal compounds and adjusting their ratios, the invention achieves a contrast ratio above 10:1 while maintaining a response time of 1 millisecond or less, preventing the direct proportionality between elastic constant and response time that would otherwise exist.
4Stability of the object's composition
If the temperature range of the nematic phase is expanded to improve operational stability, then the service temperature range increases, but the viscosity at operating temperatures increases
Solution Approach 1:
The patent resolves this contradiction by selecting a viscosity range of 5 to 20 mPa·s at 20°C and controlling dielectric anisotropy between 0.5 and 2.0. This parameter optimization ensures that the liquid crystal composition maintains appropriate flow characteristics across the nematic phase temperature range while preserving fast response times, preventing the direct proportionality between temperature range stability and viscosity that would otherwise exist.
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 solution achieves a flicker rate of 0% to 1%, a short response time, large voltage holding ratio, low threshold voltage, high contrast ratio, and extended service life, while maintaining stability to ultraviolet light and heat, making it suitable for various liquid crystal display modes and applications.
Implementation Method 1
a liquid crystal composition having positive dielectric anisotropy, which is placed between these substrates
Implementation Method 2
The optical anisotropy of the composition relates to the contrast ratio of the device. A large optical anisotropy or a small optical anisotropy, namely a suitable optical anisotropy, is necessary depending on the mode of the device.
Implementation Method 3
The temperature range of a nematic phase relates to the temperature range in which the device can be used. A desirable maximum temperature of the nematic phase is approximately 70 °C or higher and a desirable minimum temperature of the nematic phase is approximately -10 °C or lower.
Data Source
AI summary
Subject The subject is to provide a liquid crystal display device having characteristics such as a short response time, a large voltage holding ratio, a low threshold voltage, a large contrast ratio, a long service life and a small flicker rate. Means for solution The means concerns a liquid crystal display device including a first substrate, a second substrate and a liquid crystal composition having positive dielectric anisotropy, which is placed between these substrates, wherein the liquid crystal composition has a nematic phase and includes at least one compound selected from the group of compounds represented by formula (1) as a first component: in formula (1), R1 is alkyl or the like; ring A is 1,4-phenylene or the like; Z1 is a single bond or the like; X1 and X2 is hydrogen or fluorine; Y1 is fluorine or the like; and m is 0, 1, 2, 3 or 4.