Electrophoretic Color Display Layer for Bright White and Saturated Colors
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Solution Overview
Problem
Existing color display technologies using color filters result in dim white states and compromised color gamut, making them unsuitable for displays requiring high brightness and contrast, such as e-readers.
Innovation Solution
A display layer utilizing an electrophoretic medium with five or six types of particles, each with distinct optical characteristics and charge polarities, driven by specific electric fields to achieve multiple color states, including a neutral buoyancy particle to enhance brightness and contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If color filters are added on top of black/white sub-pixels to achieve color display, then color display capability is improved, but white state brightness deteriorates
Solution Approach 1:
The pixel is divided into multiple sub-pixels (red, green, blue, and white sub-pixels) that can be independently controlled. This segmentation allows the white sub-pixel to provide bright white light while color sub-pixels provide saturated colors, resolving the contradiction between color display capability and white state brightness.
Solution Approach 2:
The display uses a composite structure combining color filters with a white sub-pixel layer. The white sub-pixel acts as a bright light source that can be combined with color sub-pixels to achieve both high white state brightness and saturated color display.
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 display dynamically controls the activation of different sub-pixels based on the desired output. When white display is needed, the white sub-pixel is activated; when saturated colors are needed, only the color sub-pixels are activated. This dynamic control allows the system to achieve both high white level and color saturation at different times without compromise.
3Illumination intensity
If color saturation of sub-pixels is reduced to achieve brighter colors, then color brightness is improved, but color gamut deteriorates
Solution Approach 1:
The invention merges the functions of bright white light generation (white sub-pixel) and saturated color generation (color sub-pixels) into a single pixel structure. By combining the light output from white sub-pixel with color sub-pixels, the system achieves both bright colors and wide color gamut 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 provides brighter and more saturated colors, improving the display's white state brightness and overall image quality, suitable for high-quality displays.
Implementation Method 1
an electrophoretic medium comprising a fluid and first, second, third, fourth and fifth types of particles dispersed in the fluid... the first, third and fourth types of particles having charges of one polarity and the second and fifth types of particles having charges of the opposite polarity
Implementation Method 2
a neutral buoyancy particle to enhance brightness and contrast
Data Source
AI summary
The invention relates to electrophoretic layers containing at least five different particles, and to driving methods for displaying at least five, and in some embodiments, six different colors at each pixel or sub-pixel. The electrophoretic layers may also contain uncharged neutral buoyancy particles, and the driving methods may include special shaking waveform sequences.