Liquid-Crystal Medium for Fast Response and Low Viscosity
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Solution Overview
Problem
Current liquid-crystal mixtures for displays, particularly in MLC, FFS, IPS, TN, and STN displays, face challenges such as low specific resistance, high rotational viscosities, and temperature dependence, leading to issues like after-image retention and limited operational temperature ranges, which affect display performance and longevity.
Innovation Solution
Incorporating specific compounds of the formula I, which provide high dielectric anisotropy, low rotational viscosities, and broad nematic phase ranges, along with compounds from formulae II to XXVIII, to create liquid-crystal mixtures with improved thermal and UV stability, high specific resistance, and reduced threshold voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional liquid-crystal mixtures are used, then the display can operate at standard temperatures, but the specific resistance is low and rotational viscosity is high, leading to after-image retention and slow response times
Solution Approach 1:
The patent changes the chemical composition parameters by introducing compounds with specific molecular structures (formula I with A1, L1 substituents and formulae II-XXVIII) that inherently possess high dielectric anisotropy and low rotational viscosity. This chemical parameter change simultaneously improves specific resistance and response time without requiring external adjustments
Solution Approach 2:
The patent creates a composite liquid-crystal mixture by combining multiple compounds with complementary properties: compounds of formula I provide high dielectric anisotropy and broad nematic phase ranges, while compounds of formulae II-XXVIII contribute low rotational viscosities and enhanced stability. The synergistic combination achieves both high specific resistance and fast response times
2Stability of the object's composition
If liquid-crystal mixtures with high rotational viscosity are used, then the mixture may have stable phase properties, but the response time increases and addressing becomes slower
Solution Approach 1:
The patent modifies the viscosity parameter by incorporating compounds of formulae II-XXVIII that specifically target rotational viscosity reduction. These compounds maintain phase stability through their molecular structures while reducing the energy barrier for molecular reorientation, thereby decreasing rotational viscosity and addressing time
3Device complexity
If liquid-crystal mixtures with narrow nematic phase ranges are used, then the mixture may have simpler composition, but the operational temperature range is limited
Solution Approach 1:
The patent adjusts the thermal parameters by selecting compounds with specific melting points and clearing points. The compounds of formula I and formulae II-XXVIII are chosen to have thermal properties that, when combined, create a broad nematic phase range extending to low temperatures, thereby expanding the operational temperature window
4Device complexity
If liquid-crystal mixtures with high threshold voltages are used, then the mixture may have simpler structure, but the energy consumption increases and display performance deteriorates
Solution Approach 1:
The patent changes the dielectric parameters by incorporating compounds of formula I that possess high dielectric anisotropy. This increased dielectric anisotropy enhances the liquid crystal's response to applied electric fields, thereby reducing the threshold voltage required for switching and decreasing energy consumption
5Speed
If liquid-crystal mixtures with low specific resistance are used, then the mixture may have faster molecular reorientation, but after-image retention occurs and display contrast deteriorates
Solution Approach 1:
The patent creates a composite mixture where compounds of formula I provide high dielectric anisotropy for fast response, while compounds of formulae II-XXVIII contribute to enhanced specific resistance. The composite structure balances molecular reorientation speed with electrical stability, achieving both fast response and high display contrast without after-image retention
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 resulting liquid-crystal mixtures exhibit enhanced performance with increased specific resistance, reduced rotational viscosities, broad nematic phase ranges, and improved low-temperature stability, enabling faster response times and longer operational lifetimes while maintaining low threshold voltages.
Implementation Method 1
the optical properties of such substances can be modified by an applied voltage... Materials for cells having a twisted nematic structure should have positive dielectric anisotropy
Implementation Method 2
SBE (superbirefringence effect) cells and OMI (optical mode interference) cells
Data Source
AI summary
The invention relates to a liquid-crystalline medium which comprises at least one compound of the formula I,in whichR1 and R1* each, independently of one another, denote an alkyl or alkoxy radical having 1 to 15 C atoms, where, in addition, one or more CH2 groups in these radicals may each be replaced, independently of one another, byin such a way that O atoms are not linked directly to one another, and in which, in addition, one or more H atoms may be replaced by halogen,A1 denotesL1 denotes F, Cl, CF3, OCF3 or CHF2,and to the use thereof for electro-optical purposes, in particular for shutter glasses, 3D applications, in TN, PS-TN, STN, TN-TFT, OCB, IPS, PS-IPS, FFS, PS-FFS and PS-VA-IPS displays.