Capacitance Electrode Overlap for Electrophoretic Display Leakage
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Solution Overview
Problem
In electrophoretic display devices, electric field leakage through gaps between pixel electrodes causes erroneous actions of the electrophoretic element and deterioration of display quality due to the overlapping capacitance electrodes.
Innovation Solution
The design includes a capacitance electrode that overlaps the pixel electrode over its entire periphery, with a width of the connection part being less than the capacitance parts, and the use of interlayer insulating films to manage the electric field and reduce parasitic capacitance, ensuring uniform electric field strength and minimizing leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the capacitance electrode is formed over substantially the entire surface of the display part with all pixel electrodes overlapping it, then the capacitance coverage is maximized, but electric field leakage occurs through gaps of adjacent pixel electrodes causing erroneous action of the electrophoretic element
Solution Approach 1:
The patent applies local quality by making the capacitance electrode transparent in the gap regions between adjacent pixel electrodes. This allows the capacitance electrode to maintain full surface coverage for maximum capacitance while being locally modified (transparent) in specific regions to prevent electric field leakage through the gaps, thus resolving the contradiction between coverage and leakage prevention
2Quantity of substance
If the capacitance electrode extends beyond the pixel electrode edges, then the capacitance coverage is improved, but electric field leakage through gaps increases causing display quality deterioration
Solution Approach 1:
The patent makes the capacitance electrode transparent specifically in the gap regions between pixel electrodes while maintaining opaque or reflective properties in the overlapping regions. This local differentiation allows the electrode to extend beyond pixel edges for improved capacitance coverage without causing display quality deterioration, as the transparent regions prevent unwanted electric field leakage
3Object-affected harmful factors
If a transparent insulating film is used in the gap regions, then electric field leakage is suppressed, but the device complexity increases due to additional layer requirements
Solution Approach 1:
The patent makes the capacitance electrode itself transparent in the gap regions, allowing it to serve dual functions: maintaining electrical connectivity and capacitance coverage while simultaneously preventing electric field leakage. This eliminates the need for separate transparent insulating films in gap regions, thus suppressing electric field leakage without significantly increasing device complexity
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 configuration effectively suppresses electric field leakage, prevents malfunction of the electrophoretic element, and maintains high display quality by ensuring uniform electric field distribution across the display surface.
Implementation Method 1
an electrophoretic display device in which an electrophoretic element is held between an element substrate and a counter substrate
Data Source
AI summary
According to one embodiment, a display device includes a base substrate, a switching element including a semiconductor layer, a power supply line, a pixel electrode electrically connected to the switching element, a capacitance electrode positioned between the base substrate and the pixel electrode and electrically connected to the power supply line, a first interlayer insulating film positioned between the pixel electrode and the capacitance electrode, a common electrode, and an electrophoretic element positioned between the pixel electrode and the common electrode. An edge of the capacitance electrode overlaps the pixel electrode over the entire periphery thereof.