Liquid Crystal Composition for Residual Image Reduction

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Solution Overview

Problem

Liquid crystal displays (LCDs) suffer from residual images due to ion impurities that are concentrated at the boundaries of field generating electrodes, affecting transmittance and image quality, particularly with the diversification of LCD uses requiring low voltage driving, high voltage holding ratio, wide viewing angles, and fast response times.

Innovation Solution

A liquid crystal composition comprising a first class with a fluorine-containing compound and a second class of liquid crystal compounds, where the second class includes specific compounds represented by Formulae I, II, and III, with controlled terminal groups to minimize the presence of alkenyl groups, which reduces ion impurity interaction and refractive anisotropy changes, thereby minimizing residual images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional liquid crystal composition is used, then the liquid crystal display can operate with basic functionality, but residual images occur due to ion impurity concentration at electrode boundaries

Engineering Contradiction:

Improveresidual image reductionVSAvoidion impurity concentration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent modifies the chemical composition parameters of the liquid crystal material by incorporating specific fluorinated compounds and compounds with particular terminal groups (Formulae I-III) to change the physical and chemical properties of the liquid crystal composition, thereby reducing ion impurity concentration and residual image effects

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite liquid crystal composition by combining multiple components including fluorinated liquid crystal compounds (first class) and specific liquid crystal compounds (second class represented by Formulae I-III), where the synergistic interaction between components reduces ion impurity concentration and residual image formation

Inventive Principle:

Principle #40Composite materials

2Use of energy by moving object

If the liquid crystal composition is optimized for low voltage driving, then energy consumption is reduced, but other characteristics such as voltage holding ratio and response time may be compromised

Engineering Contradiction:

Improvevoltage drivingVSAvoidoperational characteristics

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The patent designs a liquid crystal composition that simultaneously achieves multiple functions: low voltage driving capability, high voltage holding ratio, fast response time, and wide viewing angle. The composite composition with fluorinated compounds and specific terminal group compounds provides multi-functional performance, making the LCD adaptable to diverse operational requirements

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 composition significantly extends the line residual image revelation time, maintaining desirable dielectric, refractive anisotropy, and rotational viscosity characteristics, ensuring improved image quality and durability.

Implementation Method 1

the alignment of liquid crystal molecules in the liquid crystal layer is determined by the electric field

Methodology Applied

Scientific EffectMolecular alignment:

Implementation Method 2

maintaining desirable dielectric, refractive anisotropy, and rotational viscosity characteristics

Methodology Applied

Scientific EffectRefractive anisotropy:

Implementation Method 3

maintaining desirable dielectric, refractive anisotropy, and rotational viscosity characteristics

Methodology Applied

Scientific EffectDielectric anisotropy:

Implementation Method 4

The ion impurities may be laterally transported along an electric field formed in the liquid crystal layer and concentrated at a predetermined portion

Methodology Applied

Scientific EffectIon impurity transport: Electrophoresis

Data Source

PatentUS7815979B2Liquid crystal composition and liquid crystal display including same

Publication Date: 2010.10.19 SAMSUNG DISPLAY CO LTD

AI summary

Disclosed is a liquid crystal display that includes a first substrate, a second substrate facing the first substrate, a pair of field generating electrodes formed on at least one of the first substrate and the second substrate, and a liquid crystal layer interposed between the first substrate and the second substrate. The liquid crystal layer comprises a liquid crystal composition that includes a first class having at least one fluorine atom, and a second class containing a neutral compound. The second class includes a first sub-class and a second sub-class. The first sub-class contains a liquid crystal compound having at least one selected from an alkyl group and an alkoxy group having C1 to C5 in a terminal group thereof. The second sub-class contains a liquid crystal compound having an alkenyl group having C1 to C5 in terminal groups thereof. The second sub-class is contained in a content of about 7 wt % or less of a total content of the liquid crystal composition.