Cholesteric Liquid Crystal Mixture for Stable Haze Control

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Solution Overview

Problem

Bistable liquid-crystal-based light modulating devices face instability due to external environment factors, leading to decreased electro-optic performance and uniformity, particularly in cholesteric liquid crystal devices which struggle to maintain high haze in the light scattering state and low haze in the transparent state.

Innovation Solution

A liquid crystal mixture comprising specific compounds of formulas I and II, along with chiral compounds, is used to enhance stability, with component B making up 40%-95% of the mixture, inducing spiral twisting of nematic liquid crystal molecules to form chiral nematic liquid crystals, thereby maintaining high haze in the light scattering state and low haze in the transparent state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cholesteric liquid crystals are used to form periodic spiral texture, then high haze in light scattering state and angular-independent transparency are achieved, but stability of electro-optic performance decreases due to sensitivity to external environment

Engineering Contradiction:

Improvestability of electro-optic performanceVSAvoidsensitivity to external environment

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent uses a composite liquid crystal mixture containing specific compounds of formula I (with mesogenic groups MG1 and MG2), compounds of formula II (cyclic carbonates), and chiral compounds. This composite formulation creates a more stable cholesteric liquid crystal system that maintains electro-optic performance while achieving the desired optical states.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent optimizes specific molecular structure parameters including the carbon chain length (3-40 atoms) in compound I, the substituent groups (R1-R4 being -H, -F, -Cl or alkyl groups), and the ring structures (H1-H3) in compound II. These parameter adjustments enhance the stability of the liquid crystal mixture against environmental factors while maintaining the periodic spiral texture formation.

Inventive Principle:

Principle #35Parameter changes

2Duration of action of stationary object

If liquid crystal materials are exposed to external environment conditions for long time, then device operation is maintained, but electron cloud distribution becomes abnormal causing decreased optical uniformity

Engineering Contradiction:

Improveoperational durationVSAvoidoptical uniformity

Core Design Contradiction:

Duration of action of stationary objectVSReliability

Solution Approach 1:

The patent incorporates compounds of formula II (cyclic carbonates) as stabilizing agents in the liquid crystal mixture. These compounds act as protective components that preemptively counteract the degrading effects of long-term exposure to light, temperature changes, and moisture, preventing abnormal electron cloud distribution and maintaining optical uniformity throughout the device's operational life.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If conventional liquid crystal mixtures are used, then device manufacturing is simplified, but haze control in transparent and light scattering states is insufficient

Engineering Contradiction:

Improvehaze control performanceVSAvoidliquid crystal mixture composition

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs compounds with specific localized structural features: mesogenic groups (MG1, MG2) at specific positions in compound I, cyclic carbonate structures in compound II, and chiral centers in the chiral compounds. These localized structural qualities enable precise control over the liquid crystal's optical properties, achieving superior haze differentiation between transparent and light scattering states.

Inventive Principle:

Principle #3Local quality

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 liquid crystal mixture improves the stability of electro-optic performance by maintaining high haze in the light scattering state and low haze in the transparent state, enhancing the optical performance and resistance to environmental factors like UV exposure and temperature changes.

Implementation Method 1

component C comprised of one or more chiral compounds... inducing spiral twisting of nematic liquid crystal molecules to form chiral nematic liquid crystals

Methodology Applied

Scientific EffectSpiral twisting of liquid crystal molecules: Cholesteric Liquid Crystal

Implementation Method 2

a liquid-crystal-based light modulating device is mainly comprised of transparent conductive substrates and liquid crystal materials, where the orientation of liquid crystal molecules may be manipulated by applying an external electric field

Methodology Applied

Scientific EffectElectro-optic effect: Electro-Optic Effects

Data Source

PatentUS11932799B2Liquid crystal mixture and light modulating device

Publication Date: 2024.03.19 JIANGSU JICUI INTELLIGENT LCD TECH CO LTD

AI summary

Disclosed herein is a liquid crystal mixture applied in light modulating devices, comprising: component A comprised of one or more compounds selected from the group of compounds of formula (I), component B comprised of one or more compounds selected from the group of compounds of formula (II), and component C comprised of one or more chiral compounds. Also disclosed is a light modulating device containing the liquid crystal mixture, wherein the liquid crystal mixture has higher stability of electrical performance and the light modulating device has improved optical performance.