Electrophoretic Display Pixels with Multi-Threshold Charged Particles
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Solution Overview
Problem
Electrophoretic displays struggle to accurately display white color due to limitations in color gamut and contrast ratio, as they rely on red, green, and blue charged particles, which cannot produce a bright white without separate white pixels, leading to reduced contrast and color representation.
Innovation Solution
An electrophoretic display with pixels containing colored and white charged particles, where each particle has distinct threshold voltages for repulsive and attractive forces, allowing for the creation of red, green, blue, white, and black colors by adjusting voltage levels, eliminating the need for separate white pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If red, green, and blue charged particles are used to display colors in electrophoretic displays, then the display can show various colors, but it cannot display true white color with sufficient brightness
Solution Approach 1:
The patent combines white charged particles with colored charged particles (red, green, blue, cyan, magenta, yellow) within the same pixel. This merging allows the pixel to display both colored states and true white state by controlling the movement and arrangement of different particle types through applied voltages, achieving sufficient white brightness without sacrificing color gamut.
2Illumination intensity
If separate white pixels are added to achieve true white display, then white brightness is improved, but the device complexity and pixel structure are increased
Solution Approach 1:
The patent makes each pixel multi-functional by including both colored charged particles and white charged particles within the same pixel structure. This allows a single pixel to perform multiple functions: displaying various colors through colored particles and displaying true white through white particles, eliminating the need for separate white pixels and reducing device complexity.
Solution Approach 2:
The patent uses dynamic voltage control to move different types of charged particles (colored and white) to different positions within the pixel. By applying specific voltages, the display can dynamically switch between colored states and white state, providing true white display without requiring static separate white pixel structures.
3Illumination intensity
If white pixels are used to display white color, then white brightness is achieved, but the contrast ratio is reduced
Solution Approach 1:
The patent employs periodic voltage application to control the movement of white and colored charged particles. By applying voltages in specific sequences and durations, the system can achieve stable white display states with sufficient brightness while maintaining the ability to transition to colored states, thereby preserving contrast ratio through dynamic particle arrangement rather than static pixel differentiation.
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
This solution enhances color gamut and contrast ratio by enabling the display of a wider range of colors and improving brightness, specifically achieving a true white and black representation without the limitations of traditional white pixels.
Implementation Method 1
The horizontal electric field electrophoretic display displays images by applying a voltage to the two field generating electrodes, thus generating a horizontal electric field that causes white and black charged particles to move toward those electrodes that have the same polarity.
Implementation Method 2
Each charged particle has at least two threshold voltages, where the threshold voltages are voltage magnitudes below which a voltage applied across the first and second electrodes does not move the associated charged particle.
Data Source
AI summary
An electrophoretic display according to an exemplary embodiment of the present invention may include: a first substrate, a first electrode formed on the first substrate, a second electrode spaced apart from the first electrode, a second substrate facing the first substrate, and a plurality of charged particles arranged between the first substrate and the second substrate, pairs of the charged particles having different polarities. Each charged particle has at least two threshold voltages, where the threshold voltages are voltage magnitudes below which a voltage applied across the first and second electrodes does not move the associated charged particle. The pixels may represent any one of colors such as red, green, blue, white, and black by including two charged particles of different colors in one pixel and changing the attractive and repulsive force threshold voltages of each of two charged particles of different colors contained in the pixel.