Liquid Crystal Composition Stability and Response Speed
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Solution Overview
Problem
Liquid crystal compositions for display devices face challenges in maintaining stability against heat and light while ensuring high voltage holding ratio and preventing display defects like image sticking and variations, while also requiring low viscosity, high response speed, and a wide operating temperature range.
Innovation Solution
A liquid crystal composition containing a specific compound represented by the general formula (I), which includes various substituents and groups to enhance stability and performance, is developed to address the issues of stability, voltage holding ratio, and display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a liquid crystal composition is designed for high-speed response with low viscosity and low γ1, then response speed is improved, but stability toward heat and light deteriorates, leading to display defects
Solution Approach 1:
The patent employs a composite liquid crystal composition containing multiple specific compounds (cyclic carbonate compounds, carboxylic acid compounds, and their derivatives) in defined concentration ranges. This composite approach allows the composition to achieve both high-speed response characteristics (low viscosity, low γ1) and high stability toward heat and light (high VHR ≥ 90%), preventing display defects while maintaining fast response performance.
2Reliability
If the voltage holding ratio is increased to prevent display defects, then reliability is improved, but the complexity of composition increases due to multiple additives
Solution Approach 1:
The patent achieves high voltage holding ratio (≥90%) by precisely controlling the concentrations of specific compounds within defined ranges: cyclic carbonate compounds (0.1-10 wt%), carboxylic acid compounds (0.1-10 wt%), and their specific derivatives. This parameter optimization allows the base liquid crystal composition to inherently provide high stability without requiring additional antioxidant or UV absorber additives, thus maintaining composition simplicity while achieving high reliability.
3Reliability
If the liquid crystal composition is optimized for high absolute Δε and high Tni, then low-voltage drive and wide operating temperature range are improved, but viscosity increases, reducing response speed
Solution Approach 1:
The patent introduces specific compounds with targeted molecular structures and properties into the liquid crystal composition. Cyclic carbonate compounds and carboxylic acid compounds are selected for their specific molecular characteristics that locally enhance dielectric constant anisotropy (Δε) and nematic-isotropic transition temperature (Tni) without proportionally increasing viscosity. This allows different regions of the composition to contribute different properties, achieving high absolute Δε and wide temperature range while maintaining low viscosity and fast response speed.
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 stability towards heat and light, maintains a high voltage holding ratio, and reduces display defects, ensuring high display quality and response speed.
Implementation Method 1
Liquid crystal materials having a negative dielectric constant anisotropy (Δε) are characteristically used in the IPS mode, an electrically controlled birefringence (ECB) mode, the VA mode
Implementation Method 2
an electrically controlled birefringence (ECB) mode
Data Source
AI summary
The present application provides a liquid crystal composition with high dielectric constant anisotropy and a low viscosity, and to provide a liquid crystal display device with high contrast, high-speed responsivity, high light fastness, and high display quality without image sticking and display defects. The liquid crystal composition contains one or two or more compounds represented by the general formula (I). The liquid crystal composition is of great practical use as a liquid crystal composition for use in liquid crystal displays and is effective for high contrast, high-speed response, and high quality reliability.