Radial Branch Electrode Structure for Flexible Touch Substrates
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Solution Overview
Problem
In capacitive touch screens, particularly in flexible AMOLED display screens, the parasitic capacitance between the touch electrode and the cathode is high, leading to reduced sensitivity and accuracy due to a small effective conductive area and increased RC delay.
Innovation Solution
A touch substrate with a radial branch electrode distribution structure, where the first and second electrodes form an occlusal structure with alternately disposed branch electrodes, increasing the facing area and reducing impedance, thereby enhancing the parasitic capacitance change and sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the touch electrode is made directly on the upper surface of the thin-film encapsulation layer, then the device structure is simplified, but the parasitic capacitance between the touch electrode and cathode increases, resulting in reduced touch sensitivity
Solution Approach 1:
The touch electrode is divided into multiple segments: a first touch electrode pattern on the upper surface of the thin-film encapsulation layer, and a second touch electrode pattern on the lower surface of the color filter layer. This segmentation allows the electrode to be distributed across multiple layers, reducing the concentrated parasitic capacitance between any single electrode and the cathode while maintaining the simplified overall structure.
Solution Approach 2:
The touch electrode design extends from a two-dimensional surface pattern into the third dimension by placing portions of the electrode on different layers (upper surface of encapsulation layer and lower surface of color filter layer). This dimensional extension increases the effective electrode area without significantly increasing the horizontal footprint, thereby reducing parasitic capacitance per unit area while maintaining sensitivity.
2Area of stationary object
If a hollow metal grid material is used for the touch electrode, then the conductive area is reduced, but the mutual capacitance induction between TX and RX decreases, resulting in smaller capacitance change and reduced detection accuracy
Solution Approach 1:
The touch electrode is segmented into multiple patterns distributed across different layers rather than using a single hollow metal grid. This segmentation creates multiple capacitance induction paths between TX and RX electrodes, increasing the total mutual capacitance induction and resulting capacitance change while maintaining a compact conductive area.
Solution Approach 2:
The patent combines multiple electrode patterns from different layers into a unified touch electrode system. The first touch electrode pattern on the upper surface and the second touch electrode pattern on the lower surface work together to create enhanced mutual capacitance induction, effectively merging the capabilities of multiple electrode configurations into a single integrated system that improves detection accuracy.
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 radial branch electrode distribution structure improves the uniformity of the capacitive electric field, increases the parasitic capacitance change, and reduces RC delay, resulting in enhanced sensitivity and accuracy of touch detection.
Implementation Method 1
The capacitive touch screens detect a specific position of a finger touch by detecting capacitance change at a position of the finger touch
Implementation Method 2
a distance between the touch electrode and a cathode is small, resulting in a greater parasitic capacitance between a driving electrode (TX)/sensing electrode (RX) and the cathode
Implementation Method 3
a radial branch electrode distribution structure to improve the uniformity of a capacitive electric field
Implementation Method 4
The capacitive touch screens detect a specific position of a finger touch by detecting capacitance change at a position of the finger touch
Data Source
AI summary
A touch substrate and a display panel are provided by this disclosure. The touch substrate includes a plurality of touch units, each touch unit has a first electrode and a second electrode. The first electrode includes a first trunk electrode and a plurality of first branch electrodes. The first trunk electrode is parallel to a first direction. The first branch electrodes are disposed on two sides of the first trunk electrode. The first branch electrodes extend outwardly with the first trunk electrode as a center to form a radial structure. The second electrode includes a second trunk electrode and a plurality of second branch electrodes. The second trunk electrode is parallel to a second direction. The second branch electrodes are disposed on two sides of the second trunk electrode. The first branch electrodes and the second branch electrodes are alternately disposed to form an occlusal structure.