Low Visibility Metal Mesh Touch Sensor Design
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Solution Overview
Problem
Touch screens with highly conductive metallic mesh sensors face challenges such as rapid degradation of copper conductors and the visibility of moiré patterns, which interfere with image display clarity.
Innovation Solution
A method is developed to design and manufacture a touch sensor with a conductive metallic micro-mesh that minimizes moiré patterns by using analytical or numerical methods to model mesh periodicity, applying a constraint window, and randomizing intersection points to shift them within this window, ensuring the mesh is not visible and does not obscure images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If copper conductors are used for high conductivity, then electrical conductivity is improved, but oxidation and degradation occur rapidly
Solution Approach 1:
The patent uses a composite structure with copper conductors plated with a second metal layer (palladium or nickel). The copper provides high electrical conductivity while the outer metal layer provides oxidation resistance and passivation, creating a composite material system that combines the benefits of both materials.
2Reliability
If the second metal layer (palladium or nickel) is plated over copper, then oxidation resistance is improved, but visibility issues occur due to opacity
Solution Approach 1:
The patent applies the second metal layer selectively only at the intersections where conductors meet, rather than coating the entire conductor surface. This localized application provides oxidation protection at the most vulnerable points (intersections) while leaving the majority of the conductor surface exposed and transparent to light.
3Illumination intensity
If wire lines are made sufficiently thin to be invisible, then visibility is reduced, but moiré patterns become visible due to periodic design
Solution Approach 1:
The patent introduces randomization in the positioning of conductor intersections and varies the spacing between conductors, breaking the perfect periodic symmetry of the grid. This asymmetry and randomness disrupt the formation of moiré patterns while maintaining the overall grid structure and electrical functionality.
4Illumination intensity
If the grid of the touch sensor is made transparent, then image viewing is improved, but moiré patterns become visible when formed by the grid
Solution Approach 1:
The patent introduces randomization in the positioning of conductor intersections and varies the spacing between conductors, breaking the perfect periodic symmetry of the grid. This asymmetry and randomness disrupt the formation of moiré patterns while maintaining the overall grid structure and electrical functionality.
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 solution effectively reduces the visibility of moiré patterns, maintaining image clarity and preventing interference with the display, while ensuring the touch sensor's conductive mesh is integrated seamlessly with the display screen.
Implementation Method 1
The moiré patterns appear as a result of an interaction between similar repeated patterns that are overlaid and the patterns are displaced, rotated or have slightly different pitch from each other.
Data Source
AI summary
Touchscreen having a display device and a touch sensor adhered to the display device via optically clear adhesive; wherein the touch sensor comprises a transparent substrate; a top metal mesh divided into channels; a bottom metal mesh divided into channels; each of the top and bottom metal meshes having line spacing calculated to avoid first order moiré patterns and then the intersections of the lines randomized to avoid secondary order moiré patterns.