Electrophoretic Particle Surface Modification for Charging

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Solution Overview

Problem

Electrophoretic display systems face issues with low charging capacity of electrophoretic particles, leading to decreased display density and mixed color displays, along with instability in the dispersion medium and increased viscosity.

Innovation Solution

Incorporating a polymer with a reactive compound represented by Formula (I) on the surface of electrophoretic particles, which includes a (meth)acrylate group and a carbonyl or ester group, allowing for enhanced charging capabilities and improved dispersion stability by orienting these groups for optimal function.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional electrophoretic particles are used, then the display system can operate with basic charging properties, but the charging amount is insufficient leading to decreased display density and mixed color displays

Engineering Contradiction:

Improvecharging amountVSAvoiddisplay stability

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent modifies the chemical composition parameters of the particle surface by incorporating specific reactive compounds (Formula I) with carbonyl or ester groups that have high electron affinity. This changes the electrical properties of the particle surface, enabling increased charging amount while maintaining display stability through controlled electron interaction mechanisms.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates composite particle structures by combining conventional electrophoretic particle materials with surface-modifying reactive compounds. This composite approach allows the core particle to maintain its electrophoretic mobility while the surface layer provides enhanced charging capabilities, resolving the contradiction between charging amount and display stability.

Inventive Principle:

Principle #40Composite materials

2Quantity of substance

If the particle surface is modified to increase charging amount, then display density improves, but the complexity of particle manufacturing increases

Engineering Contradiction:

Improvecharging amountVSAvoidparticle manufacturing complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent applies surface modification treatment during the particle manufacturing process rather than as a separate subsequent step. The reactive compounds are incorporated into the particle formation process itself, allowing the charging-enhancing surface layer to be created simultaneously with the particle core, thereby reducing overall manufacturing complexity despite the advanced functionality achieved.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If electrophoretic particles are moved repeatedly for display cycles, then the display can show different images, but the charging properties change leading to decreased display performance

Engineering Contradiction:

Improvedisplay cycle capabilityVSAvoidcharging stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent incorporates reactive compounds with electron-affinity groups into the particle surface structure in advance, creating a stable charging mechanism that resists degradation during repeated display cycles. This preliminary structural enhancement cushions against the cumulative effects of repeated electrophoretic movement, maintaining consistent charging properties and display performance over time.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 results in electrophoretic particles with increased charging capacity, improved display density, suppressed viscosity, and enhanced separation properties, leading to stable and clear color displays.

Implementation Method 1

Methodology Applied

Scientific EffectElectrostatic charge accumulation: Electrostatics

Implementation Method 2

display is performed by alternately moving electrophoretic particles to a visible surface and a back surface in a cell by creating an electric field, using electrophoretic particles charged in liquid

Methodology Applied

Scientific EffectElectrophoresis: Electrophoresis

Data Source

PatentUS9671667B2Electrophoretic particle, electrophoretic particle dispersion liquid, display medium, and display device

Publication Date: 2017.06.06 E INK CORP

AI summary

An electrophoretic particle includes a polymer having at least a reactive compound represented by the following Formula (I) as a polymerizable component, at least on a surface:wherein in Formula (I), Ra represents a hydrogen atom or a methyl group, X represents a substituted or unsubstituted divalent hydrocarbon group, Y represents a substituted or unsubstituted divalent hydrocarbon group, and Z represents a hydrogen atom, or a substituted or unsubstituted monovalent hydrocarbon group.