Curved Edge Touch Sensor Electrodes Reduce Stress Concentration
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Solution Overview
Problem
Conventional touch sensors made of brittle materials like ITO are prone to breakage when bent due to stress concentration at the edges of touch electrode patterns, leading to functional failure.
Innovation Solution
A touch sensor design featuring independent sensing sub-electrodes and leads in the same layer, with curved bumps or recesses at the edges and curved leads to reduce stress concentration, manufactured using a single masking process, which enhances touch sensitivity and visibility while minimizing manufacturing complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional touch sensors are made of ITO transparent conductive films, then the touch sensor can be manufactured with standard processes, but the touch sensor breaks due to stress concentration at edges when bent
Solution Approach 1:
The patent applies curvature by replacing straight edges of touch electrode patterns with curved edges having a specific radius of curvature (R1). This curvature design prevents stress concentration at sharp corners during bending, thereby reducing breakage risk while maintaining manufacturing feasibility with standard photolithography processes
Solution Approach 2:
The patent changes the geometric parameter of the electrode edges from sharp corners to curved edges with optimized radius of curvature (R1). This parameter modification reduces stress concentration during bending while maintaining the electrical functionality and manufacturability of the touch sensor
2Device complexity
If touch electrode patterns have straight edges, then the manufacturing process is simple, but stress concentrates at edges causing breakage
Solution Approach 1:
The patent introduces curved edges with radius of curvature R1 to replace straight edges in touch electrode patterns. This geometric modification increases manufacturing complexity slightly but dramatically reduces stress concentration at edges during bending, thereby improving reliability
3Reliability
If the touch sensor uses complex bridging processes to prevent breakage, then breakage risk is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies curvature (radius of curvature R1) to the electrode edges during the initial patterning process, before any bending or stress testing occurs. This preliminary geometric modification prevents stress concentration from the outset, eliminating the need for subsequent bridging processes or additional protective measures
Data Source
AI summary
A touch sensor is provided and includes: a sensing electrode, having sensing sub-electrodes arranged in an array; and a plurality of sensing electrode leads, arranged between adjacent two of the sensing sub-electrodes and connected to the sensing sub-electrodes. An edge of the sensing sub-electrodes includes a curved bump/recess, and the bumps and the recess of adjacent two of the sensing sub-electrodes are complementary to each other. The sensing electrode leads are arranged in a curved shape in a gap between adjacent two of the sensing sub-electrodes.