Electrophoretic Fluid Color Display Without Filters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional color display technologies using color filters result in dim white states and reduced color saturation, making them unsuitable for applications like e-readers that require high readability and contrast.
Innovation Solution
An electrophoretic fluid comprising three types of pigment particles with different charge polarities and mobility levels, dispersed in a solvent, is used to create a color display device that eliminates the need for color filters, allowing for highly saturated color states by controlling the movement of particles between electrode layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If color filters are added on top of black/white sub-pixels to achieve color display, then color states can be displayed, but the white state becomes dim and color saturation is reduced
Solution Approach 1:
The patent removes color filters from the display structure entirely. Instead of using color filters on sub-pixels, the invention uses electrophoretic particles that inherently provide color through their optical properties. The colored particles (cyan, magenta, yellow) and black/white particles directly create color states without requiring color filtering, thereby eliminating the complexity and light loss associated with color filters.
Solution Approach 2:
The patent replaces the optical filtering mechanism (color filters) with an electrophoretic mechanism. Instead of using physical color filters to select wavelengths, the system uses electrically controlled particle movement to create color states. The electrophoretic particles are moved between electrodes to form desired color patterns, substituting mechanical/optical filtering with electrical control of particle positioning.
2Illumination intensity
If a fourth white sub-pixel is added to double the white level, then white brightness is improved, but color saturation is reduced as each sub-pixel becomes only one fourth of the pixel area
Solution Approach 1:
The patent segments the pixel into multiple independently controllable electrophoretic particle groups (colored particles and black/white particles). Each particle type can be independently positioned and controlled, allowing full-color pixels to achieve both high white brightness and high color saturation simultaneously. The segmentation of particle functions replaces the segmented sub-pixel approach, enabling better performance in both white level and color saturation.
3Illumination intensity
If color saturation of three sub-pixels is reduced to achieve brighter colors, then white level improves slightly, but the white level remains substantially less than half of that of a black and white display
Solution Approach 1:
The patent uses composite electrophoretic fluid containing multiple types of particles (colored particles, black particles, white particles) with different optical properties. This composite approach allows the system to achieve high white brightness by combining the reflective properties of white particles with the color properties of colored particles, simultaneously achieving high white level and high color saturation without the trade-offs of conventional color filter displays.
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 the display of highly saturated colors without the need for color filters, achieving brighter and more readable color states, particularly in applications requiring high contrast and brightness, such as e-readers.
Implementation Method 1
An electrophoretic fluid comprising three types of pigment particles with different charge polarities and mobility levels, dispersed in a solvent, is used to create a color display device
Data Source
AI summary
The present invention provides a solution for a highlight or multicolor display device, in which each display cell can display high quality color states. More specifically, an electrophoretic fluid is provided which comprises three types of pigment particles, having different levels of size, threshold voltage or charge intensity.