Liquid Crystal Medium for Fast Switching and Low Voltage ECB Displays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid crystal displays using the ECB effect with negative dielectric anisotropy liquid crystals face challenges in achieving short switching times, high voltage holding ratio, and low operational voltages, leading to high current consumption and insufficient contrast and viewing angle stability, particularly in mobile and TV applications.
Innovation Solution
A liquid-crystalline medium based on a mixture of polar compounds, including specific formula I compounds, is used, which provides a broad nematic phase range, high negative dielectric anisotropy, and low rotational viscosity, enabling efficient electro-optical performance with improved switching times and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If liquid crystal media with negative dielectric anisotropy are used for ECB displays, then the operational voltage can be kept low, but the switching time becomes too long
Solution Approach 1:
The patent changes the physical and chemical parameters of the liquid crystal compounds by introducing specific molecular structures (cyclohexenylene units with fluorinated phenyl groups) that simultaneously optimize dielectric anisotropy, rotational viscosity, and switching response. This resolves the contradiction by finding compound formulations that achieve both low operational voltage and fast switching time through parameter optimization rather than compromise
Solution Approach 2:
The patent uses composite liquid crystal media containing multiple compounds with different properties (cyclohexenylene derivatives, fluorinated phenyl compounds, and other mesogenic substances) to achieve synergistic effects. The composite formulation combines compounds with high negative dielectric anisotropy for low voltage operation with compounds having low rotational viscosity for fast switching, resolving the technical contradiction
2Reliability
If compounds with negative dielectric anisotropy are used predominantly, then the voltage holding ratio improves, but the switching time increases
Solution Approach 1:
The patent optimizes the molecular parameters of the liquid crystal compounds by incorporating cyclohexenylene units with specific substituent patterns that enhance both dielectric anisotropy (for voltage holding) and reduce rotational viscosity (for switching speed). The fluorinated phenyl groups specifically tune the dielectric properties while the overall molecular structure controls viscosity, resolving the contradiction between reliability and speed
3Speed
If the rotational viscosity is reduced to improve switching time, then the switching time becomes short, but the voltage holding ratio decreases
Solution Approach 1:
The patent employs composite liquid crystal formulations where different compounds perform complementary functions: some compounds (with specific cyclohexenylene structures) provide low rotational viscosity for fast switching, while other compounds (with fluorinated phenyl groups) maintain high dielectric anisotropy for voltage holding. The composite approach allows simultaneous optimization of both properties without compromise
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 short switching times, high voltage holding ratio, and low operational voltages, enhancing the performance and stability of liquid crystal displays, particularly in mobile and TV applications, while maintaining low rotational viscosity and broad nematic phase ranges.
Implementation Method 1
Liquid crystal displays that use the ECB (E electrically C controlled B irefringence) effect with dielectrically negative liquid crystals
Implementation Method 2
liquid crystalline media with negative dielectric anisotropy (Δε)
Implementation Method 3
the liquid crystals are used as dielectrics whose optical properties change reversibly when an electrical voltage is applied
Data Source
AI summary
Liquid crystalline medium (A) comprises a mixture of dielectric negative, polar cyclohexane compounds (I). Liquid crystalline medium (A) comprises a mixture of dielectric negative, polar cyclohexane compounds of formula (I). R 11>, R 12> : H, up to 15C-unsubstituted alkyl or -alkenyl (where one or more CH 2-groups are substituted by -O-, -S-, -cyclobutane-1,4-yl-, -C?=C-, -CF 2-O-, -O-CF 2-, -CO-O- or -O-CO- (where O atoms are not directly connected)); ring A 11>-ring A 14> : 2,3-difluoro-benzene-1,4-yl, tetrahydro-pyran-2,5-yl moieties (all preferred), 3-chloro-2-fluoro-benzene-1,4-yl, 2-chloro-3-fluoro-benzene-1,4-yl, cyclohexene-1,4-yl moieties, cyclohexane-1,4-yl, 2-fluoro-cyclohexene-1,4-yl moieties, [1,3]dioxane-2,5-yl moieties, benzene-1,4-yl, 2-fluoro-benzene-1,4-yl moieties or 2,3-difluoro-benzene-1,4-yl; Z 11>-Z 13> : -CH 2-CH 2-, -CH=CH-, -C?=C-, -CH 2-O-, -O-CH 2-, -CO-O-, -O-CO-, -CF 2-O-, -O-CF 2-, -CF 2-CF 2- or a bond (preferred); and m, n : 0 or 1. An independent claim is included for an electro optical display comprising (A). [Image].