Coloured Polymer Particles for Non-Polar Electrophoretic Displays
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Solution Overview
Problem
Current electrophoretic displays (EPDs) lack a bright full-color system and require complex cell structures and drive schemes, and existing colored particles are difficult to disperse in non-polar media without leaching color, limiting their application in low-power, low-cost, and lightweight display devices.
Innovation Solution
Development of specifically engineered colored polymer particles with pre-polymerized dyes for electrophoretic devices, which are synthesized to have controlled size, charge, and color, and are stable in non-polar media, allowing for easy dispersion and long-term color retention without leaching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If different coloured particles are used in a single pixel to achieve full color display, then color brightness and variety are improved, but cell structure complexity and drive scheme complexity increase
Solution Approach 1:
The invention segments the color generation function from the particle system by using a single white light-emitting LED combined with color filters in the substrate layers, rather than using multiple colored particles or LEDs per pixel. This allows full-color display while maintaining simple cell structure.
Solution Approach 2:
Color filter layers are introduced as intermediary elements between the white light source and the observer. These filters selectively transmit different wavelengths to create the perception of different colors, eliminating the need for complex multi-particle systems.
2Illumination intensity
If conventional colored particles are used in EPDs, then color display is achieved, but color leaching occurs in non-polar media over time
Solution Approach 1:
The invention uses composite microcapsule structures containing both the colored particles and the color filter materials within a single stable matrix. This composite structure prevents color leaching while maintaining display functionality in non-polar media.
Solution Approach 2:
The microcapsules act as flexible shells that encapsulate the colored particles and color filters, providing a stable barrier that prevents color leaching into the non-polar dispersion medium while allowing the particles to maintain their electrophoretic mobility.
3Reliability
If complex preparation processes are used to create colored particles with charge and dispersibility, then particle performance is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention merges multiple functions (color filtration, particle encapsulation, charge stabilization, and dispersibility) into a single integrated microcapsule structure. This is achieved by co-polymerizing functional monomers that provide all these properties simultaneously, eliminating the need for separate preparation steps.
Solution Approach 2:
The invention changes the chemical parameters of the particle surface by incorporating specific functional monomers (acrylic acid, methacrylic acid, or carboxylic acid groups) during polymerization. This modifies the surface properties to provide both charge retention and dispersibility in non-polar media without complex post-treatment.
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 enables the production of high-quality, full-color electrophoretic displays with excellent image quality, fast response times, and consistent surface properties, suitable for various applications, including e-paper, with independent control over charge and color, and no color leaching in non-polar solvents.
Implementation Method 1
charged electrophoretic particles dispersed between two substrates, each comprising one or more electrodes... If a voltage is applied between the electrodes, charged particles move to the electrode of opposite polarity
Data Source
AI summary
This invention relates to coloured polymer particles preferably with surface functionality for charge retention, a process for their preparation, the use of these particles for the preparation of an electrophoretic device, and to colour electrophoretic displays comprising such particles.