Liquid Crystalline Medium for Fast Switching and Low-Temperature Stability

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing liquid crystal mixtures for electro-optical displays, particularly those using the ECB, IPS, and FFS effects, face challenges with high specific resistance, slow switching times, and limited temperature stability, which affect display performance and reliability, especially in extreme temperatures.

Innovation Solution

The use of specific liquid-crystalline media containing compounds of formulas IA, IB, IC, ID, and IE, along with compounds of formulas IIA, IIB, IIC, and O-17, which improve rotational viscosities, elastic constants, and dielectric anisotropy, resulting in mixtures with short switching times, broad nematic phase ranges, and enhanced low-temperature stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional liquid crystal mixtures are used, then the display can operate, but the switching times are slow and temperature stability is limited

Engineering Contradiction:

Improveswitching timesVSAvoidtemperature stability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent modifies the molecular structure of liquid crystal compounds by introducing specific chemical groups (cyclohexyl, fluorine substitutions, ester linkages) to change physical parameters such as rotational viscosity and elastic constants. This results in faster switching times while maintaining temperature stability through optimized molecular configurations.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite liquid crystal mixtures combining multiple compounds with different molecular structures (cyclohexyl benzoates, fluorinated compounds, ester derivatives). These composite mixtures achieve synergistic effects where the combination of components provides both fast switching characteristics and broad temperature stability that individual compounds cannot achieve alone.

Inventive Principle:

Principle #40Composite materials

2Speed

If liquid crystal mixtures with fast switching times are developed, then switching performance improves, but rotational viscosity and elastic constants become difficult to optimize

Engineering Contradiction:

Improveswitching timesVSAvoidmixture composition complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent introduces specific functional groups at particular positions in the molecular structure (fluorine atoms at specific carbon positions, cyclohexyl rings at terminal positions) to locally modify molecular properties. This allows precise control over rotational viscosity and elastic constants without requiring complex overall molecular structures, simplifying the mixture composition while achieving fast switching.

Inventive Principle:

Principle #3Local quality

3Temperature

If the nematic phase range is broadened for extreme temperature operation, then temperature stability improves, but the specificity of liquid crystal properties may be reduced

Engineering Contradiction:

Improvenematic phase rangeVSAvoidliquid crystal property stability

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent employs nested molecular structures where rigid core units (benzene rings, cyclohexyl rings) are nested within flexible linker chains (ester groups, alkoxy chains). This nested configuration allows the rigid cores to maintain liquid crystal specificity and phase stability while the flexible linkers broaden the nematic phase range to accommodate extreme temperatures.

Inventive Principle:

Principle #7Nested doll (Nesting)

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

These mixtures exhibit improved rotational viscosities, elastic constants, and dielectric properties, leading to faster switching times, increased reliability, and improved temperature stability, addressing the limitations of previous liquid crystal materials.

Implementation Method 1

The invention relates to a liquid-crystalline medium which is suitable for electro-optical displays with active matrix addressing based on the ECB effect

Methodology Applied

Scientific EffectElectrically controlled birefringence (ECB effect): Birefringence

Implementation Method 2

such as for IPS displays (In plane switching)

Methodology Applied

Scientific EffectIn plane switching (IPS):

Implementation Method 3

or FFS displays (Fringe Field Switching)

Methodology Applied

Scientific EffectFringe field switching (FFS):

Data Source

PatentEP3067405B1Liquid crystalline medium

Publication Date: 2019.03.27 MERCK PATENT GMBH

AI summary

The invention relates to a liquid crystalline medium containing at least one compound of formula IA, IB, IC, ID and/or IE, wherein Z1 is a single bond, -CH2CH2-, -CH=CH-, -CH2O-, -OCH2-, -CF2O- -OCF2-, -COO-, -OCO-, -C2F4-, -C≡C-, -CF=CF-, -CH=CHCHO-, and its use for an active matrix display, in particular based on the VA-, PSA-, PS-VA-, PALC-, FFS-, PS-FFS-, PS-IPS- or IPS effect.