Electrophoretic Display Device Using Additive Particles for Bright Color
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional color display devices using color filters to achieve white states result in dim and unsaturated colors, making them unsuitable for applications requiring high readability and contrast, such as e-readers.
Innovation Solution
An electrophoretic display device utilizing a fluid comprising four types of particles - white, black, colored, and additive particles - dispersed in a dielectric solvent, where the additive particles enhance color brightness and hiding power by moving under an electric field to block or enhance colors, eliminating the need for color filters.
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 because each sub-pixel has only one third reflectance
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 (absorption and scattering characteristics), eliminating the need for color filters and improving white state brightness.
Solution Approach 2:
The patent changes the optical parameters of the display medium by using particles with specific absorption and scattering properties. The electrophoretic particles are designed with wavelength-selective absorption characteristics, allowing them to provide saturated colors without requiring color filters, thereby improving both color saturation and white state brightness.
2Illumination intensity
If a fourth white sub-pixel is added to double the white level, then white brightness is improved, but color saturation decreases because each color sub-pixel becomes only one fourth of the pixel area
Solution Approach 1:
The patent segments the color display function into multiple electrophoretic particle types, each responsible for different wavelength ranges. Instead of relying on sub-pixel area division, the invention uses spectral segmentation where different particle types (with different absorption characteristics) combine to produce full-color display, maintaining color saturation while improving white level.
Solution Approach 2:
The patent uses a composite electrophoretic fluid containing multiple types of particles with different optical properties. The combination of particles with selective absorption characteristics creates a composite material that provides both saturated colors and high white level without requiring reduced sub-pixel areas.
3Illumination intensity
If light from white pixels is added to achieve brighter colors, then color brightness is improved, but color gamut is reduced causing colors to be light and unsaturated
Solution Approach 1:
The patent introduces electrophoretic particles as intermediaries that selectively absorb and scatter light wavelengths. These particles act as optical mediators that enhance color brightness through their scattering properties while maintaining color gamut through their wavelength-selective absorption characteristics, avoiding the need to add white light which would desaturate colors.
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 with improved brightness and contrast, suitable for applications requiring high readability and contrast, such as e-readers, by effectively managing particle movement and color blocking within the display cells.
Implementation Method 1
an electrophoretic display device utilizing a fluid comprising four types of particles - white, black, colored, and additive particles - dispersed in a dielectric solvent, where the additive particles enhance color brightness and hiding power by moving under an electric field
Implementation Method 2
the additive particles enhance color brightness and hiding power by moving under an electric field to block or enhance colors
Implementation Method 3
first particles that have the property of scattering light over an entire visible range
Implementation Method 4
second particles that have the property of absorbing light of a specific wavelength range in the visible range
Data Source
Figure 1
Figure 2~2(c)
Figure 3~3(b)
AI summary
The present invention provides a realistic solution for a highlight or multicolor display device which can display high quality color states. More specifically, an electrophoretic fluid is provided which comprises four types of particles, having different levels of size, threshold voltage or charge intensity.