Touch Panel Non-Uniform Node Layout for SMT Routing
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Solution Overview
Problem
Touch sensor panels with surface-mounted components create dead zones and non-uniform touch sensitivity due to the routing of drive and sense lines, leading to weaker signal detection and phantom touches from cross-couplings.
Innovation Solution
Implementing a non-uniform touch node layout with drive and sense lines routed in a DITO pattern around SMT components and using correction gains calculated from adjacent nodes to ensure uniform sensitivity, and routing traces on a different layer to prevent cross-coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If drive lines and sense lines are routed through the area occupied by SMT components, then the touch signal strength is improved, but the SMT component placement is blocked
Solution Approach 1:
The patent routes drive lines and sense lines through multiple layers (top and bottom surfaces) of the substrate to circumvent the SMT component area. By transitioning from a single-plane routing to a three-dimensional multi-layer routing approach, the conductive lines can maintain capacitive coupling for touch detection without occupying the same physical space as the SMT component, thus resolving the conflict between signal strength and component placement.
Solution Approach 2:
The routing path of drive lines and sense lines is divided into multiple segments that traverse different layers and regions of the substrate. Instead of a single continuous path blocked by the SMT component, the lines are segmented into portions on the top surface, portions on the bottom surface, and connecting portions through vias, allowing the routing to bypass the component area while maintaining electrical continuity and capacitive sensing capability.
2Ease of manufacture
If drive lines and sense lines are routed around SMT components, then component placement is enabled, but touch sensitivity is reduced creating dead zones
Solution Approach 1:
By routing lines on both the top and bottom surfaces of the substrate, the patent creates overlapping capacitive fields that extend into the area previously designated as a dead zone. This multi-dimensional routing approach allows the electric field to penetrate through the substrate thickness, recovering touch sensitivity in regions where single-layer routing would fail.
Solution Approach 2:
The patent modifies the capacitive coupling parameters by creating DITO (Double-layer Indium Tin Oxide) patterns where drive and sense lines are positioned on opposite surfaces of the substrate. This changes the physical configuration from co-planar to three-dimensional, altering the capacitance characteristics and enabling touch detection in areas where traditional single-layer routing would create dead zones.
3Device complexity
If routing traces are on the same layer as drive and sense lines, then device complexity is reduced, but cross-coupling causes phantom touches
Solution Approach 1:
The patent separates routing traces from drive and sense lines by placing them on different layers (top versus bottom surfaces) of the substrate. This vertical separation in the third dimension eliminates parasitic capacitive coupling between routing traces and sensing lines, preventing phantom touches while maintaining a relatively simple overall device structure that doesn't require additional shielding layers or complex trace geometries.
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
Recover lost touch signals, achieve uniform sensitivity across the panel, and reduce phantom touches by routing lines around SMT components and using per-node correction gains, while shielding routing traces to prevent cross-coupling.
Implementation Method 1
each touch node can be formed by a capacitive coupling between a drive line and a sense line
Implementation Method 2
the drive and sense lines are separated by a dielectric material
Data Source
AI summary
This relates to a touch sensor panel including: a substrate having a first surface and a second surface; a first touch node formed by a first drive line and a first section of a first sense line both routed on the first surface of the substrate; and a second touch node formed by a second drive line routed on the first surface of the substrate and a second section of the first sense line routed on the second surface of the substrate.