Touch Electrode Layer with Dummy Electrodes for Flexible AMOLED
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Solution Overview
Problem
Traditional capacitive touch displays struggle to accurately detect small capacitance changes due to a thin packaging layer, leading to increased parasitic capacitance and reduced touch sensitivity, especially in flexible AMOLED display panels with hollow metal mesh electrodes.
Innovation Solution
A touch electrode layer design featuring alternately disposed first and second electrode branches with widening and connecting parts, along with dummy electrodes, increases mutual inductive capacitance and reduces parasitic capacitance, enhancing touch position detection resolution and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin packaging layer is used in flexible AMOLED display panels, then device flexibility and thinness are improved, but parasitic capacitance increases and touch sensitivity decreases
Solution Approach 1:
The touch electrode is segmented into multiple branches (first electrode branches and second electrode branches) with alternating dispositions. This segmentation increases the effective sensing area and mutual capacitance between Tx and Rx electrodes, compensating for the reduced touch sensitivity caused by the thin packaging layer.
Solution Approach 2:
The electrode design transitions from simple linear traces to two-dimensional branched structures with widening parts. The branches extend in multiple directions and include widening sections that increase the effective area in the plane dimension, thereby enhancing mutual capacitance without increasing the thickness dimension.
2Illumination intensity
If hollow metal mesh electrodes are used to reduce conductivity, then transparency is improved, but conductive area decreases and mutual capacitance becomes very small
Solution Approach 1:
The patent uses composite electrode structures combining metal mesh with transparent conductive materials. The hollow metal mesh provides structural support and partial conductivity, while the transparent conductive material fills the hollow areas and connects the mesh structures, creating a composite that maintains both transparency and sufficient conductive area.
Solution Approach 2:
The electrode structure serves multiple functions simultaneously: the metal mesh framework provides mechanical strength and baseline conductivity, the transparent conductive material ensures electrical continuity and enhances transparency, and the branched widening structure maximizes sensing area. This multi-functional design resolves the trade-off between transparency and conductive area.
3Ease of manufacture
If traditional touch electrode structures are used, then manufacturing is simple, but resolution and accuracy of touch position detection are insufficient
Solution Approach 1:
The touch electrode is divided into multiple segmented branches with specific patterns. This segmentation creates more sensing nodes and improves the spatial resolution for detecting touch position, while the branches can be fabricated using standard photolithography processes to maintain manufacturing simplicity.
Solution Approach 2:
The electrode design implements local quality variations through branching structures with different widths and densities in different regions. The widening parts and branch configurations are optimized locally to enhance sensing capability at specific positions, improving overall detection accuracy without requiring complete redesign of the entire manufacturing process.
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 design improves touch sensitivity and accuracy by increasing mutual capacitance and distributing the capacitance electric field evenly, while reducing parasitic capacitance and enhancing the signal-to-noise ratio.
Implementation Method 1
a distance between the touch electrode and the cathode is less, resulting a larger parasitic capacitance between driving electrodes (Tx) and sensing electrodes (Rx)
Implementation Method 2
the mutual capacitance between the Tx and Rx is very small, and resulting a small capacitance change when touched by a finger
Data Source
AI summary
A touch electrode layer and a touch display device are provided. The touch electrode layer includes a plurality of touch electrode units. The touch electrode unit includes a first electrode and a second electrode. The first electrode includes a first electrode branch having a first branch widening part. The second electrode includes a second electrode branch having a second branch widening part. The first electrode branch and the second electrode branch are disposed alternately, and a dummy electrode is disposed within the first electrode and the second electrode.