Electrophoretic Display Driving Method Suppressing Color Fade-Out
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Solution Overview
Problem
Microcapsule-type electrophoretic display devices suffer from 'color fade-out' or 'display blur', particularly at the border between white and black, due to leakage currents and charge migration between pixel electrodes, leading to a change in the display state over time.
Innovation Solution
A driving method for electrophoretic display devices where the pixel electrodes and common electrode are set to the same potential after image display, eliminating potential differences and preventing electric field formation, thereby maintaining the display state and suppressing color fade-out.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pixel electrodes are set to different potentials for image display, then image display function is achieved, but color fade-out occurs after display due to charge migration
Solution Approach 1:
The patent applies the equipotentiality principle by setting all pixel electrodes to the same potential (e.g., 0V or a common reference potential) after image display. This eliminates potential differences between adjacent pixel electrodes, thereby preventing charge migration through the electrophoretic element and suppressing color fade-out. The common electrode is also set to the same potential, ensuring the entire display structure is at equipotential, which stabilizes the display state without affecting the previously formed image.
2Power
If adhesive layer and microcapsule shell have low resistance for effective voltage application, then voltage application efficiency is improved, but leakage current increases causing charge migration
Solution Approach 1:
The patent applies preliminary anti-action by proactively setting all pixel electrodes and the common electrode to the same potential immediately after image display. This preemptive measure counteracts the harmful effect of leakage current by eliminating the driving force (potential difference) that would cause charge migration through the low-resistance adhesive layer and microcapsule shells. By acting before charge migration can occur, the display state is preserved despite the inherent leakage paths.
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 method effectively prevents color fade-out and maintains high-quality display by ensuring the pixel electrodes and common electrode remain at a consistent potential, preventing charge migration and electric field-induced changes in the electrophoretic element.
Implementation Method 1
In a microcapsule 20a provided on the pixel electrode 35a, black particles 26 charged positive are drawn to the pixel electrode 35a side and white particles 27 charged negative are drawn to the common electrode 37
Data Source
AI summary
A driving method of an electrophoretic display device, including a pair of substrates with an electrophoretic element which is interposed between the substrates and contains electrophoretic particles, a plurality of pixel electrodes formed at an electrophoretic element side of either one substrate of the pair of substrates, and a common electrode which opposes to the plurality of pixel electrodes and is formed at an electrophoretic element side of the other substrate, includes an image display step of inputting potentials, which are determined according to image data, to the plurality of pixel electrodes and a predetermined potential to the common electrode and displaying an image according to the image data by driving the electrophoretic element, and an image maintaining step of causing the plurality of pixel electrodes and the common electrode to have the same potential after the image display step.