Colored Electrophoretic Particles With Bound Dyes for Full-Color E-Paper
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Solution Overview
Problem
Current electrophoretic display technologies lack a simple and cost-effective method to produce charged, coloured particles that can be easily dispersed in non-polar media, maintain colour integrity, and exhibit high electrophoretic mobility, while also being suitable for full-color e-paper applications.
Innovation Solution
The development of electrophoretic fluids using specifically engineered polymer particles synthesized through a process involving polymerisable dyes, monomers, and initiators, with surface modification to promote dispersability and charge retention, allowing for the production of coloured particles with controlled size, monodispersity, and colour stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If complex cell structures and drive schemes are used to achieve different coloured particles in a single pixel, then full colour capability is achieved, but device complexity increases
Solution Approach 1:
The invention segments the colour display function into separate coloured particles (cyan, magenta, yellow) that can be independently controlled by applying voltages of different polarities. Each particle type carries a specific charge and moves to opposite electrodes, enabling full colour display through simple two-electrode configuration without complex cell structures.
Solution Approach 2:
Instead of using complex cell structures to achieve colour separation, the invention inverts the approach by using charged particles of different colours that respond to electric fields in opposite directions. The colour separation is achieved through electrophoretic movement rather than physical cell division, simplifying the overall device structure.
2Reliability
If polymerisable dyes are used to create coloured particles, then colour stability is improved, but manufacturing complexity increases
Solution Approach 1:
The invention merges the dye molecule with the polymer matrix through covalent bonding during polymerization. The polymerisable dye becomes an integral part of the polymer particle structure, ensuring colour stability while maintaining a relatively simple one-step polymerization preparation process.
Solution Approach 2:
The invention changes the chemical state of the dye from a separate component to a polymerized component within the particle structure. By incorporating polymerisable functional groups into the dye molecules, the colour is locked into the polymer matrix, preventing leaching and improving stability without requiring complex post-processing.
3Manufacturing precision
If particle size is reduced to 50-500 nm for image quality, then image resolution is improved, but manufacturing precision requirements increase
Solution Approach 1:
The invention optimizes particle size parameters to the 50-500 nm range, which provides sufficient image resolution while remaining manufacturable. This size range balances the competing requirements of image quality (requiring small particles) and manufacturing precision (becoming increasingly difficult at smaller scales).
Solution Approach 2:
The invention applies different properties to different aspects of the particles: small size (50-500 nm) for image quality, while maintaining adequate charge density for electrophoretic mobility and using polymerisable dyes for colour stability. Each parameter is optimized for its specific function.
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
This approach enables the creation of high-quality, full-color electrophoretic displays with excellent image quality, fast response times, and cost-effective production, as the polymerisable dyes become irreversibly bound to the particles, preventing colour leaching and ensuring consistent performance.
Implementation Method 1
the reaction of at least one polymerisable dye, at least one monomer, at least one initiator
Implementation Method 2
charged electrophoretic particles dispersed between two substrates, each comprising one or more electrodes. The space between the electrodes is filled with a dispersion medium. 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, colour electrophoretic displays comprising such particle, and new water-soluble dyes.