Liquid Crystal Cell Non-Ionic Additive EHDI Switching

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Solution Overview

Problem

Existing liquid crystal cells face issues with high driving voltage, residual haze, and storage reliability when switching between transparent and scattering modes, due to solubility and dispersion problems with conventional additives, leading to recrystallization and poor mixing properties.

Innovation Solution

A liquid crystal cell using a non-ionic compound with high dielectric constant as an additive to control conductivity and induce electrohydrodynamic instability, allowing for efficient switching between modes while ensuring solubility and stability, with a nematic or smectic phase liquid crystal compound and an anisotropic dye for improved haze characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional ionic compounds or charge transfer complexes are used as additives to realize EHDI characteristics, then driving voltage characteristics and haze characteristics are improved, but in-plane unevenness occurs due to solubility and dispersion differences, recrystallization occurs at room temperature, and storage reliability at low temperature is not secured

Engineering Contradiction:

Improvedriving voltage characteristic and haze characteristicVSAvoidsolubility and dispersion uniformity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent changes the chemical nature of the additive from ionic compounds to non-ionic compounds with high dielectric constants (ε≥30). This parameter change in the additive's molecular structure fundamentally alters its interaction with the liquid crystal, improving solubility and preventing recrystallization while maintaining EHDI characteristics and driving voltage performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite liquid crystal system by combining non-ionic compounds with high dielectric constants and nematic or smectic liquid crystal compounds. This composite approach leverages the high dielectric constant of the additive to enhance conductivity control and EHDI effects while the liquid crystal matrix provides solubility and prevents phase separation.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If a small amount of additive is used to avoid recrystallization, then solubility is improved, but haze characteristic is lowered and driving property deteriorates

Engineering Contradiction:

Improvesolubility and mixing propertyVSAvoidhaze characteristic

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent changes the dielectric constant parameter of the additive to be high (ε≥30), which allows achieving sufficient conductivity and EHDI effects with larger additive concentrations. This parameter change enables the system to maintain both good solubility and high haze characteristics simultaneously.

Inventive Principle:

Principle #35Parameter changes

3Power

If ionic compounds are used as additives, then EHDI characteristics are realized with good driving voltage, but transmittance variable characteristics are lowered when anisotropic dyes are added and storage reliability at low temperature is not secured

Engineering Contradiction:

Improvedriving voltage characteristicVSAvoidtransmittance variable characteristic and storage reliability

Core Design Contradiction:

PowerVSAdaptability or versatility

Solution Approach 1:

The patent changes the ionic nature of the additive to non-ionic, which eliminates the solubility and recrystallization problems associated with ionic compounds. This allows the system to maintain excellent driving voltage characteristics while also achieving good transmittance variable characteristics and storage reliability at low temperatures.

Inventive Principle:

Principle #35Parameter changes

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 provides a liquid crystal cell with excellent driving voltage, haze, and storage reliability by reducing in-plane unevenness and recrystallization, enabling effective switching between transparent and scattering modes with improved solubility and conductivity.

Implementation Method 1

a non-ionic compound with high dielectric constant as an additive to control conductivity and induce electrohydrodynamic instability

Methodology Applied

Scientific EffectElectrohydrodynamic instability (EHDI): Electrohydrodynamics

Implementation Method 2

a nematic or smectic phase liquid crystal compound

Methodology Applied

Scientific EffectLiquid crystal phase transition: Phase Change

Implementation Method 3

switching between transparent and scattering modes by applying external energy

Methodology Applied

Scientific EffectElectro-optic effect: Electro-Optic Effects

Data Source

PatentUS10941344B2Liquid crystal cell

Publication Date: 2021.03.09 LG CHEM LTD

AI summary

A liquid crystal cell which is capable of switching between a transparent mode and a scattering mode by using a non-ionic compound as a liquid crystal additive for realizing the EHDI characteristics and has excellent performance such as a driving voltage characteristic, a haze characteristic and reliability by securing solubility of the additive for liquid crystals. Such a liquid crystal cell can be applied to various light modulation devices such as a smart window, a window protective film, a flexible display device, a light shielding plate for transparent display, an active retarder for 3D image display, or a viewing angle adjusting film.