Electrophoretic Fluids with Reflective Coated Particles
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Solution Overview
Problem
Existing electrophoretic display technologies face challenges in achieving high reflectivity and color saturation due to limitations in the properties of typical color pigments used in solvents, which restrict color choice and resolution, making it difficult to generate a highly reflective color state.
Innovation Solution
The use of electrophoretic fluids comprising a solvent, colored particles, highly absorbing dyes, white reflective particles, and transparent particles with specific electric charge characteristics and mobilities, allowing for increased reflectivity and color saturation by adjusting particle spacing and applying driving schemes to achieve desired optical states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If typical color pigments are used in electrophoretic displays, then the display can show color states, but the reflectivity is not high enough to generate appropriate optical difference
Solution Approach 1:
The patent uses composite particles consisting of a colorant core coated with a reflective material shell. This composite structure combines the color properties of the core with the high reflectivity of the shell, achieving both color saturation and high reflectivity simultaneously. The reflective coating layer reflects light back through the colorant, enhancing the perceived brightness and optical contrast of the colored particles.
2Adaptability or versatility
If color pigments are used to create optical effects, then color states can be generated, but the choice of colours is limited and colour tuning is restrictive
Solution Approach 1:
The patent enables color tuning by changing the parameters of the reflective coating, such as its thickness, refractive index, and material composition. By adjusting these parameters, different wavelengths of light are reflected with varying intensities, allowing for precise color control. This approach provides greater versatility in color selection compared to using only pigment-based solutions.
3Manufacturing precision
If pigment dispersions are used for electrophoretic displays, then color states can be achieved, but high resolution printing and dispensing is very challenging
Solution Approach 1:
The patent replaces mechanical printing and dispensing processes with electrophoretic actuation. Instead of relying on high-resolution printing to place pigments in precise locations, the system uses electric fields to move the composite particles to desired positions. This substitution of mechanical placement with electrical control significantly improves manufacturing precision and simplifies the dispensing process.
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 enhances color saturation and reflectivity, enabling the creation of a strongly colored and highly reflective color state, as well as achieving grayscale and three-color pixel functionality, with improved color gamut and tunability.
Implementation Method 1
the electrophoretic mobilities of the white reflective particles and the transparent particles differ at most by 50%
Implementation Method 2
at least one highly absorbing dye
Data Source
AI summary
This invention relates to electrophoretic fluids, the use of these fluids for the preparation of an electrophoretic display device, and electrophoretic displays comprising such fluids.