Micropatterned Touch Sensor Mesh for Potential Gradient Control
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Solution Overview
Problem
Existing touch screen sensors face limitations in controlling electrical potential gradients and conductor design due to the use of continuous transparent conducting oxides like ITO, necessitating complex signal processing and additional electrodes, which are costly and limit design flexibility.
Innovation Solution
The development of micropatterned conductors with varying sheet resistance and anisotropic properties, achieved through geometric designs such as rectangular microgrids and selective breaks in meshes, allows for independent control of electrical potential gradients and improved optical quality without the need for additional electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If continuous transparent conducting oxide coating is used, then electrical conductivity is achieved, but control over electrical potential gradients is limited and additional electrodes are required
Solution Approach 1:
The continuous transparent conducting oxide coating is divided into micropatterned conductive elements (traces, lines, or shapes) with specific geometries. This segmentation allows different regions to have different electrical properties, enabling control over electrical potential gradients across the touch sensor surface without requiring additional electrodes.
Solution Approach 2:
The micropatterned conductive elements are designed with varying local properties including different trace widths, spacing, and densities in different regions of the substrate. This creates spatially varying sheet resistance values that directly control the electrical potential distribution, allowing tailored electrical characteristics for different sensing zones.
2Adaptability or versatility
If transparent conducting oxide with single sheet resistance value is used, then fabrication is simplified, but design flexibility of conductive elements is limited
Solution Approach 1:
Rather than requiring multiple TCO layers with different sheet resistance values, the invention segments a single uniform TCO coating into micropatterns with varying geometries. The effective sheet resistance is controlled by the pattern geometry (trace width, spacing, density) rather than material composition, maintaining simple single-layer fabrication while achieving diverse electrical characteristics.
Solution Approach 2:
The invention changes geometric parameters (trace width, spacing, pattern density) of the micropatterned elements to achieve different effective electrical properties from a single uniform TCO material. This allows continuous variation of effective sheet resistance across the substrate without changing material properties or adding fabrication complexity.
3Reliability
If micropatterned conductor is used, then control over electrical properties and optical quality is improved, but conductor visibility may increase
Solution Approach 1:
The invention transitions from considering only the two-dimensional electrical properties to incorporating the third dimension of optical perception. By making the pattern features smaller than the resolution limit of human vision (sub-50 micrometer, preferably sub-10 micrometer scale), the micropatterned conductors become effectively invisible while maintaining their electrical function, thus resolving the conflict between electrical control and optical quality.
Solution Approach 2:
The micropattern design optimizes local trace dimensions and spacing to balance electrical conductivity with optical transparency. Regions requiring higher conductivity use denser or wider traces, while regions prioritizing transparency use sparser or narrower traces, with all dimensions kept below visual detection thresholds to maintain overall optical quality.
Data Source
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AI summary
A touch screen sensor comprises a visible light transparent substrate and an electrically conductive micropattern disposed on or in the visible light transparent substrate. The micropattern comprises a first region micropattern within a touch sensing area. The first region micropattern includes metallic linear electrically conductive features having a width between about 1 and 10 micrometers. The first region micropattern is visible light transparent and has between about 90% and 99.5% open area. The first region micropattern includes selective breaks in conductive traces within an otherwise continuous and uniform mesh.