Metal Mesh Touch Substrate Impedance Reduction
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Solution Overview
Problem
As metal mesh touch screens increase in size, the impedance of their electrodes increases, leading to reduced touch sensitivity and limited reduction in impedance due to optical shadow elimination and bezel effects, necessitating a solution to enhance sensitivity while maintaining optical performance.
Innovation Solution
A touch substrate design featuring a base with alternating first and second electrode layers, where the first electrode layer includes first and second mesh sub-electrodes with varying cell densities and orientations, and the second electrode layer includes third and fourth mesh sub-electrodes with similar configurations, reducing resistance and maintaining uniform cell density and pattern across regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the size of metal mesh touch screens is increased, then the coverage area is improved, but the impedance of electrodes increases leading to reduced touch sensitivity
Solution Approach 1:
The electrode layer is divided into multiple sub-electrodes (first mesh sub-electrodes and second mesh sub-electrodes) with different cell densities. This segmentation allows different regions to have optimized electrode densities, reducing overall impedance while maintaining large screen area coverage.
Solution Approach 2:
Different regions of the touch screen are assigned different electrode cell densities. Regions requiring higher sensitivity have denser electrode cells, while other regions have sparser cells. This local optimization reduces overall impedance without compromising touch sensitivity in critical areas.
2Reliability
If the electrode density is increased to maintain touch sensitivity, then touch sensitivity is improved, but the optical shadow elimination effect deteriorates
Solution Approach 1:
Different regions are assigned different cell densities based on their functional requirements. Touch-sensitive regions use higher density electrodes for sensitivity, while display regions use lower density electrodes for better optical performance and shadow elimination.
Solution Approach 2:
The electrode structure is segmented into multiple sub-electrodes with varying cell densities, allowing simultaneous optimization of touch sensitivity and optical appearance in different screen regions without compromising either performance aspect.
3Reliability
If the impedance of electrodes is reduced by increasing electrode width, then impedance is improved, but the optical shadow elimination effect and bezel effects worsen
Solution Approach 1:
Instead of using fewer wide electrodes, the design segments the electrode into multiple narrower sub-electrodes with different cell densities. This achieves impedance reduction through increased electrode surface area and optimized distribution, while maintaining narrow effective widths for better optical shadow elimination.
Solution Approach 2:
The cell density parameter is varied across different regions and sub-electrodes to optimize both electrical performance (impedance) and optical performance (shadow elimination). By changing the density parameter rather than width, both electrical and optical requirements are satisfied simultaneously.
Data Source
AI summary
A touch substrate includes a base, a first electrode layer, a dielectric layer and a second electrode layer that are sequentially stacked on the base. The first electrode layer has first electrode regions and first auxiliary regions, and the second electrode layer has second electrode regions and second auxiliary regions. The first electrode layer includes a first mesh electrode including first mesh sub-electrodes and second mesh sub-electrodes. A region where each first mesh sub-electrode is located overlaps a second electrode region, and a region where each second mesh sub-electrode is located overlaps a second auxiliary region. The second electrode layer includes a second mesh electrode including third mesh sub-electrodes and fourth mesh electrodes. A region where each third mesh sub-electrode is located overlaps a first electrode region, and a region where the fourth mesh sub-electrode is located overlaps a first auxiliary region.