Flexible Touch Sensor Wiring Layout for Foldable Devices
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Solution Overview
Problem
Flexible touch sensor devices face challenges with damage risk, reduced touch sensitivity due to non-sensing regions, and increased bezel width when bent or folded, as well as high resistance in touch wiring, limiting their portability and scalability.
Innovation Solution
The design includes a layout of touch electrodes and wiring where first and second touch electrodes are positioned on either side of a reference line, with touch wiring extending non-parallel to the line, allowing for folding or bending without crossing, and utilizing conductive layers with metal nanowires and assistance layers to reduce resistance and prevent disconnections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If touch wiring is extended across the reference line to connect electrodes on both sides, then electrical connectivity is ensured, but the risk of damage increases when bent or folded
Solution Approach 1:
The touch wiring is segmented into first touch wiring connected to first touch electrodes and second touch wiring connected to second touch electrodes, with each segment extending in different directions that are non-parallel to the first direction. This segmentation allows the wiring to be distributed on different sides of the reference line without crossing, reducing stress concentration and damage risk during bending or folding while maintaining electrical connectivity to respective electrodes.
2Strength
If touch wiring is positioned to avoid crossing the reference line, then damage risk upon bending is reduced, but the bezel width increases
Solution Approach 1:
The touch wiring extends in directions that are non-parallel to the first direction (the direction of the reference line), utilizing a different dimensional orientation. This allows the wiring to connect electrodes on both sides of the reference line without extending across it in the first direction, thereby reducing bezel width while maintaining damage resistance during bending.
3Ease of manufacture
If conventional touch electrode materials are used, then manufacturing is simplified, but resistance of touch wiring increases
Solution Approach 1:
The touch electrode and touch wiring are formed using composite materials including metal nanowires (such as silver nanowire or AgNW), carbon nanotubes, graphene, metal mesh, or conductive polymers. These composite materials provide both low resistance and flexibility, improving sheet resistance margins while maintaining ease of manufacture through established deposition techniques.
Data Source
AI summary
A flexible touch sensor device with improved durability is presented. More particularly, a flexible touch sensor device that can be bent or folded with low risk of damaging the wiring is presented. The touch sensor device includes: a plurality of first touch electrodes positioned at a first side of a first reference line extending in a first direction; a plurality of second touch electrodes positioned at a second side of the first reference line; first touch wiring connected to the first touch electrodes; and second touch wiring connected to the second touch electrodes, wherein the first touch wiring and the second touch wiring extend along a second direction that is non-parallel to the first direction without crossing the first reference line.