Rectangular Touch Node Design for Metal Mesh On-Cell Sensors
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Solution Overview
Problem
Capacitive touch sensor panels face challenges in maintaining touch linearity due to the truncation of touch nodes along the edges, leading to non-symmetrical drive and sense electrodes, which affects the uniformity of touch signals across the panel.
Innovation Solution
The use of mixed-shape touch nodes, including square and rectangular designs, with localized bridge connections and varying electrode sizes and shapes to maintain symmetry and uniformity, ensuring that the areas dedicated to each electrode are kept close to each other to achieve better touch linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If touch nodes are truncated along the edges to fit panel boundaries, then the panel can be manufactured with standard dimensions, but touch linearity deteriorates due to non-symmetrical electrode configurations
Solution Approach 1:
The patent applies asymmetry by intentionally designing different electrode configurations for edge touch nodes versus center touch nodes. Edge touch nodes have non-symmetrical electrode arrangements adapted to the truncated geometry, while center touch nodes maintain symmetrical configurations. This asymmetric approach allows each region to be optimized for its specific geometric constraints, resolving the contradiction between manufacturability and touch linearity.
Solution Approach 2:
The patent implements local quality by varying the electrode design based on the specific location within the panel. Center touch nodes use symmetrical electrode configurations optimized for linear touch response, while edge touch nodes use adapted non-symmetrical configurations that account for the truncated geometry. Each local region receives the quality of electrode design appropriate to its position, maintaining overall touch linearity despite edge truncation.
2Device complexity
If uniform square touch nodes are used across the entire panel, then the design is simple and manufacturing is easy, but touch linearity performance deteriorates in edge regions due to truncation
Solution Approach 1:
The patent segments the touch node design into different types based on location: center touch nodes and edge touch nodes. Each segment has a specialized electrode configuration optimized for its region. Center nodes use symmetrical designs while edge nodes use adapted designs accounting for truncation. This segmentation allows simple manufacturing of each node type while achieving high overall precision through localized optimization.
Solution Approach 2:
The patent applies local quality by making the touch node design non-uniform across the panel. Different regions receive different electrode configurations tailored to their specific requirements. This local customization resolves the contradiction by allowing simple, uniform designs where appropriate (center regions) while applying adapted designs where needed (edge regions), maintaining both design simplicity and manufacturing precision.
3Manufacturing precision
If electrode areas are made equal in all touch nodes, then symmetry is maintained and touch linearity improves, but the ability to accommodate edge truncation is reduced
Solution Approach 1:
The patent uses asymmetry to resolve the contradiction between maintaining equal electrode areas for symmetry and accommodating edge truncation. Edge touch nodes deliberately employ non-symmetrical electrode configurations that adapt to the truncated geometry, while center touch nodes maintain symmetrical configurations with equal electrode areas. This selective asymmetry allows the system to accommodate edge truncation without sacrificing touch linearity in center regions.
Solution Approach 2:
The patent implements local quality by making electrode area equality location-dependent. Center touch nodes maintain equal electrode areas to maximize symmetry and touch linearity, while edge touch nodes use non-equal areas adapted to the truncated geometry. This local differentiation allows the system to simultaneously achieve good touch linearity in center regions and adaptability in edge regions, resolving the contradiction between these two requirements.
Data Source
AI summary
A touch sensor panel is disclosed. In some examples, the touch sensor panel includes drive electrodes and sense electrodes, wherein the drive electrodes and sense electrodes form touch nodes. In some examples, touch nodes include differently-sized drive and/or sense electrodes, and changes to the size or quantity of reference or floating electrodes disposed within the drive and/or sense electrodes are used to substantially balance the areas of the drive and/or sense electrodes in a given touch node.