Touch Panel Composite Electrode Structure for Low Resistance
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Solution Overview
Problem
Conventional touch modules using ITO as touch electrodes face limitations in medium-sized and large-sized applications due to high resistance issues.
Innovation Solution
A touch panel design featuring a substrate with a first and second sensing electrode layer, where the second-axis conductive units comprise two first conductive layers with higher resistance and a second conductive layer of lower resistance laminated between them, along with insulating layers to reduce circuit resistance, suitable for medium-sized and large-sized touch modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ITO is used as the touch electrode material, then the touch panel can be manufactured with conventional processes, but the resistance is too high for medium-sized and large-sized products
Solution Approach 1:
The patent uses a composite conductive structure consisting of three layers: a first conductive layer (ITO), a second conductive layer (silver nanowires or metallic material), and a third conductive layer (ITO). This composite structure combines the advantages of different materials to achieve low resistance while maintaining transparency, enabling the touch panel to be suitable for medium-sized and large-sized products.
Solution Approach 2:
The patent applies different materials with different properties to different regions and layers of the conductive structure. The silver nanowire layer is specifically positioned in the second conductive layer to provide low-resistance pathways, while the ITO layers provide transparency and conformal coverage. This local optimization of material properties achieves both low resistance and high transparency.
2Reliability
If a composite conductive structure with multiple layers is used, then the resistance is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The conductive structure is segmented into three distinct functional layers: first conductive layer (ITO), second conductive layer (silver nanowires), and third conductive layer (ITO). Each layer has a specific function and can be optimized independently, making the complex structure more manageable and manufacturable through sequential deposition processes.
Solution Approach 2:
The composite conductive structure serves multiple functions simultaneously: it provides low resistance for electrical conductivity, maintains high transparency for optical performance, enables flexible patterning for electrode design, and offers robustness through the multi-layer architecture. This multi-functionality reduces the need for additional separate components.
3Reliability
If silver nanowires are used in the second conductive layer, then the resistance is significantly reduced, but the control over wire distribution and resistance uniformity becomes challenging
Solution Approach 1:
The first and third ITO conductive layers act as intermediary layers that conformally cover the silver nanowire layer. These intermediary ITO layers provide a uniform conductive surface that masks the non-uniformity of the underlying silver nanowire distribution, ensuring consistent electrical performance across the touch panel while maintaining the low-resistance benefit of the silver nanowires.
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 touch panel effectively reduces resistance in the touch region, making it suitable for medium-sized and large-sized touch modules by utilizing a composite conductive structure with a silver layer and ITO, achieving a sheet resistance range of 6.76 ohm/sq to 9.6 ohm/sq.
Implementation Method 1
each of the second-axis conductive units includes two first conductive layers and a second conductive layer laminated between the two first conductive layers, and resistances of the two first conductive layers are greater than a resistance of the second conductive layer
Implementation Method 2
The second insulating layer includes a high refractive index material. In an embodiment of the disclosure, the high refractive index material is a liquid sol-gel or a liquid high refractive index optical coating. In an embodiment of the disclosure, a refractive index of the high refractive index material is substantially in a range from 1.6 to 1.8
Data Source
AI summary
A touch panel includes a substrate, a first sensing electrode layer, and a second sensing electrode layer. The first sensing electrode layer is disposed on the substrate and includes a plurality of first-axis conductive units separated from each other. The second sensing electrode layer is disposed on the substrate and includes a plurality of second-axis conductive units separated from each other and crossing the first-axis conductive units. Each of the second-axis conductive units includes two first conductive layers and a second conductive layer laminated between the first conductive layers.