Reflective Color Display Addressed by Incident Light
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Solution Overview
Problem
Existing electro-optic displays, particularly those using electrophoretic media, face challenges with particle settling and require significant energy for image refreshment, especially in high-background lighting environments like outdoor advertising.
Innovation Solution
A reflective color display system comprising a color filter array, a transparent electrode, an electro-optic medium, and a photoconductive material with a rear electrode, allowing image writing with a light source and maintaining the image without additional energy input due to bistable properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electrophoretic media are used in electro-optic displays, then the display can achieve bistable states with minimal energy consumption, but particle settling occurs causing image degradation
Solution Approach 1:
The patent removes particles from the electro-optic medium, transitioning from particle-based electrophoretic displays to a particle-free electro-optic medium. This extraction eliminates particle settling while maintaining bistability through the inherent properties of the electro-optic material itself, resolving the contradiction between energy efficiency and image stability.
Solution Approach 2:
The patent changes the fundamental parameter of the electro-optic medium by eliminating particles and using a particle-free material that exhibits electro-optic effects. This parameter change allows the display to maintain stable images without the settling issues inherent in particle-based systems, while still achieving low energy consumption through bistable operation.
2Illumination intensity
If conventional electro-optic displays are used in high-background lighting environments, then the display can be viewed outdoors, but significant energy is required for image refreshment
Solution Approach 1:
The patent implements periodic action by refreshing the display image only when content changes rather than continuously. The bistable nature of the particle-free electro-optic medium allows images to be maintained without energy input, and refreshment occurs periodically only when needed, significantly reducing energy consumption while maintaining outdoor viewability.
Solution Approach 2:
The display system uses self-service by leveraging the bistable properties of the electro-optic medium to maintain images without continuous energy input. Once an image is written, it persists automatically without requiring power to sustain it, allowing the display to serve itself and eliminating the need for continuous energy consumption during image maintenance.
3Adaptability or versatility
If particles are suspended in fluid for electrophoretic display, then the display can achieve color states, but particle settling and clustering occur
Solution Approach 1:
The patent extracts particles from the fluid suspension, transitioning to a particle-free electro-optic medium. This removal eliminates the settling and clustering problems inherent in suspended particle systems while preserving color display capabilities through the electro-optic properties of the particle-free material, resolving the contradiction between color versatility and compositional stability.
Solution Approach 2:
The patent uses composite materials by combining the electro-optic medium with a fluid medium in a way that eliminates particle suspension. The particle-free electro-optic material integrated with the fluid creates a composite system that achieves both color display capability and uniform composition stability without the drawbacks of particle-based systems.
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 system enables energy-efficient, long-lasting image retention in high-background lighting conditions, suitable for large-format displays like billboards, with minimal energy required for refreshing content.
Implementation Method 1
a photoconductive material with a rear electrode, allowing image writing with a light source
Implementation Method 2
the material being changed from its first to its second display state by application of an electric field to the material
Implementation Method 3
The display will display the color image for a time with minimal or no additional energy input, and may be subsequently re-written, as desired
Data Source
AI summary
A reflective color display that can be addressed from the front (viewing surface side) of the display with a light source, such as a projector, LED, or laser. The display comprises (in order) a color filter array, a transparent electrode, an electro-optic medium, a photoconductive material, and a rear electrode. The color displays of the invention are useful for large format color signage, such as billboards and wayfinding.