Reflective Display Device with Multi-Phase Polymer Matrix
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Solution Overview
Problem
Existing reflective display technologies, such as those using microencapsulated electrophoretic ink and liquid crystals, suffer from poor whiteness and light reflectance, making them appear grey rather than white, which affects their suitability for outdoor and bright indoor applications.
Innovation Solution
The method involves creating a reflective display device with an electro-optical layer that includes microencapsulated electro-optical fluid shells dispersed in a polymer matrix, with additional phases having different refractive indices, such as air or high refractive index solids, to enhance diffuse light reflection and scattering, thereby improving the whiteness and brightness of the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If microencapsulated electro-optical fluid shells are dispersed in a polymer matrix, then the display device achieves reflective functionality, but the whiteness and light reflectance remain poor causing grey appearance
Solution Approach 1:
The electro-optical layer is formulated as a composite material system comprising microencapsulated electro-optical fluid shells dispersed in a polymer matrix, creating a multi-phase structure that combines the reflective properties of the electro-optical fluid with the structural stability of the polymer matrix
Solution Approach 2:
The patent introduces phases with locally differentiated refractive indices within the electro-optical layer, where specific regions have optimized optical properties to enhance light scattering and reflection at interfaces, improving overall whiteness without requiring complete restructuring of the entire layer
2Illumination intensity
If additional phases with different refractive indices are added to enhance diffuse light reflection, then whiteness and brightness improve, but the electro-optical layer structure becomes more complex
Solution Approach 1:
The polymer matrix acts as an intermediary phase between the microencapsulated electro-optical fluid shells and the external environment, providing a medium with a refractive index that differs from both the shells and the surrounding medium, thereby enhancing light scattering and diffuse reflection at multiple interfaces
Solution Approach 2:
The patent optimizes the refractive index parameters of the polymer matrix and the spacing between capsules to control light scattering behavior, adjusting these parameters to achieve maximum diffuse reflectance and whiteness in the electro-optical layer
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 significantly increases the diffuse reflectance of the white state to ≥40% for electrophoretic ink devices and ≥30% for liquid crystal devices, enhancing luminance without sacrificing contrast, and allows for improved color representation through increased spectral power distribution.
Implementation Method 1
introducing to the electro-optical layer light scattering centers at the interfaces between such phase and the other phases in the electro-optical layer
Implementation Method 2
having a refractive index differing from that of said shells
Data Source
AI summary
A method of manufacturing a reflective display device comprises depositing an electro-optical ink on a substrate, the electro-optical ink comprising a plurality of microencapsulated electro-optical fluid shells dispersed in a polymer pre-cursor. The electro-optical ink is cured to provide an electro-optical layer in which the shells are maintained in a polymer matrix having at least two-phases. At least one of the phases in the polymer matrix has a refractive index differing from the shells. At least one electrode is provided in contact with the electro-optical layer to, in use, control the state of the electro-optical layer.