Color Electrophoretic Display with Segmented Sub-Pixels
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Solution Overview
Problem
Conventional color displays using color filters to achieve multicolors result in a dim white state and reduced color saturation, making them unsuitable for devices requiring high readability and contrast, such as e-readers.
Innovation Solution
A color electrophoretic display device comprising display cells filled with a mixture of oppositely charged white and colored pigment particles dispersed in a colored solvent, allowing for the creation of vibrant colors and improved white state brightness by manipulating the particle positions with electrode voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If color filters are added on top of black/white sub-pixels to achieve multicolor display, then color display capability is improved, but white state brightness deteriorates
Solution Approach 1:
The display is divided into multiple sub-pixels (red, green, blue, and white sub-pixel) that can be independently controlled. Each sub-pixel contains pigment particles that can be selectively positioned to achieve different color states, allowing the white sub-pixel to provide full brightness while color sub-pixels provide color saturation.
Solution Approach 2:
The invention uses a composite electrophoretic fluid containing multiple types of pigment particles (white pigment particles and colored pigment particles) with different charges dispersed in a solvent. This composite material allows simultaneous presence of white and colored particles in the same display cell, enabling both bright white state and saturated color state.
2Illumination intensity
If a fourth white sub-pixel is added to double the white level, then white state brightness is improved, but color saturation deteriorates
Solution Approach 1:
The pixel is segmented into four independent sub-pixels, each capable of displaying black or white state. By controlling which sub-pixels are active, the system can achieve full white brightness (when white sub-pixel is active) or full color saturation (when color sub-pixels are active and white sub-pixel is black).
Solution Approach 2:
The electrophoretic pigment particles can dynamically switch between black and white states in each sub-pixel, allowing flexible combination of white and color sub-pixels to achieve either bright white display or saturated color display as needed.
3Illumination intensity
If light from white pixel is added to achieve brighter colors, then color brightness is improved, but color saturation deteriorates
Solution Approach 1:
The invention merges the advantages of black/white display with color display by combining white sub-pixel and color sub-pixels in the same pixel structure. The white sub-pixel provides bright background when needed, while color sub-pixels provide saturated colors, and they can work together to achieve both brightness and saturation simultaneously.
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 high-quality color displays with improved white state brightness and color saturation, comparable to black and white displays, while maintaining the ability to show red, green, and blue colors effectively, addressing the limitations of traditional color filter-based displays.
Implementation Method 1
a color electrophoretic display device comprising display cells filled with a mixture of oppositely charged white and colored pigment particles dispersed in a colored solvent, allowing for the creation of vibrant colors and improved white state brightness by manipulating the particle positions with electrode voltages
Data Source
AI summary
The present invention is directed to a color display device wherein each of the display cells is filled with an electrophoretic fluid comprising two types of charged pigment particles dispersed in a colored medium. Multiple colors of high quality may be achieved by the present invention.