Color Electrophoretic Display Partial Updates for Reduced Edge Ghosting
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Solution Overview
Problem
Color electrophoretic displays suffer from issues such as edge ghosting, blooming, and unwanted color transitions during partial updates, leading to inaccurate color representation and phantom images due to inter-pixel coupling.
Innovation Solution
A method for partial updates in color electrophoretic displays involves determining identical color data across pixels and their neighbors, sending waveforms only to pixels with differing data, and omitting waveforms where all pixels and their neighbors have identical data, minimizing unintended color state drift and ghosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If waveforms are sent to all pixels during partial updates, then color transitions are complete, but edge ghosting and blooming occur due to inter-pixel coupling
Solution Approach 1:
The patent applies local quality by differentiating the update behavior of pixels based on their spatial relationship to updated neighbors. Pixels are categorized into three groups: (1) pixels with color data changes, (2) pixels with identical color data but updated neighbors (cardinal neighbors), and (3) pixels with identical color data and no updated neighbors. This localized differentiation eliminates edge ghosting for pixels in group (3) while maintaining color accuracy for pixels in groups (1) and (2).
Solution Approach 2:
The patent segments the pixel array into distinct update zones based on color data comparison and neighbor analysis. By segmenting pixels into those requiring update and those not requiring update (isolated identical pixels), the system avoids applying waveforms to pixels that would otherwise experience blooming from adjacent updated pixels, thereby eliminating edge ghosting artifacts.
2Object-generated harmful factors
If waveforms are sent to pixels with identical color data to prevent edge ghosting, then ghosting is reduced, but energy consumption increases
Solution Approach 1:
The patent uses local quality analysis to determine which pixels require waveform application. By examining both the pixel's own color data and the color data of its cardinal neighbors, the system identifies isolated identical pixels (group 3) that do not require updates. This selective approach reduces energy consumption by omitting waveforms to these pixels while still preventing edge ghosting at the boundaries of updated regions.
Solution Approach 2:
The patent applies partial action by sending waveforms only to pixels that truly need them (groups 1 and 2), rather than to all pixels in the display array. This partial update strategy maintains sufficient action to prevent edge ghosting at updated boundaries while avoiding excessive energy consumption that would result from updating all pixels regardless of necessity.
3Adaptability or versatility
If dithering is used to increase available colors, then color gamut is improved, but cross-talk between dithered subpixels causes color inaccuracies
Solution Approach 1:
The patent applies preliminary anti-action by proactively identifying and protecting dithered pixels from inter-pixel coupling effects. By detecting pixels with identical color data surrounded by non-updated identical neighbors, the system preemptively prevents the cross-talk that would otherwise occur during partial updates, thereby maintaining color accuracy for dithered regions while preserving the expanded color gamut benefits.
4Reliability
If all pixels are updated during transitions, then color transitions are accurate, but the perceived flashiness increases
Solution Approach 1:
The patent applies local quality by selectively updating only those pixels that require color transitions or are adjacent to transitioning pixels. By identifying isolated identical pixels (group 3) that have both identical color data and non-updated neighbors, the system locally suppresses updates in regions where they would contribute to flashiness, while maintaining accurate color transitions in regions where updates are necessary.
Solution Approach 2:
The patent uses partial action to update only the necessary subset of pixels rather than all pixels. This partial update approach maintains sufficient action to ensure accurate color transitions at updated boundaries while reducing excessive action (unnecessary updates) in stable regions, thereby reducing perceived flashiness during transitions.
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 approach reduces the perceived 'flashiness' of transitions, minimizes ghosting, and conserves energy by reducing the number of pixels being updated, resulting in improved color accuracy and reduced energy consumption.
Implementation Method 1
An electrophoretic display changes color by modifying the position of a charged colored particle with respect to a light-transmissive viewing surface
Data Source
AI summary
Methods for improved partial updates in color electrophoretic displays. By identifying transition borders between pixels receiving null updates (no voltage sent to pixel electrode) and color updates, problematic pixels, which would have received null updates, are caused to update to a same color state, thereby reducing edge ghosting in the updated image and improving the color in the updated image.