Capacitive Touch Sensor Trace Pattern Design
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Solution Overview
Problem
Current projected capacitive touch sensors face challenges in achieving optimal production efficiency, visual interference reduction, and multi-touch capabilities while maintaining sensitivity, particularly in designs that compromise between trace width, pitch, and pattern complexity.
Innovation Solution
The implementation of a sensor grid with trace patterns featuring rotational and radial symmetry, utilizing conductive traces with specific segment lengths and orientations to minimize visual interference and enhance production efficiency, while maintaining high sensitivity for multi-touch detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If trace patterns with straight lines and sharp corners are used, then production time is reduced, but visual interference increases
Solution Approach 1:
The patent applies curvature by replacing sharp corners with curved transitions in the trace patterns. The traces incorporate smooth curved segments instead of abrupt angular changes, which reduces visual interference (moiré effects) while maintaining manufacturing efficiency. This is achieved by defining trace paths with continuous curvature that follow optimized geometric patterns.
Solution Approach 2:
The patent employs asymmetric trace patterns where traces are deliberately positioned and shaped to avoid symmetric repetition that causes visual interference. The trace layout uses asymmetric spacing and routing strategies to break up regular patterns that create moiré effects, while still maintaining manufacturing feasibility through systematic design rules.
2Object-affected harmful factors
If trace width is increased to reduce visual interference, then sensitivity decreases
Solution Approach 1:
The patent applies local quality by varying trace characteristics in different regions of the sensor grid. Trace width, spacing, and curvature radius are locally optimized based on position-specific requirements: traces in regions requiring lower visual interference have different properties than those requiring higher sensitivity, allowing simultaneous optimization of both parameters across the entire sensor surface.
Solution Approach 2:
The patent systematically changes geometric parameters of the trace patterns, including trace width, spacing, curvature radius, and pitch ratios. By optimizing these parameters within specific ranges (e.g., trace-to-pitch ratios between 0.1-0.3), the patent achieves a balance where visual interference is reduced without sacrificing the capacitive coupling strength needed for sensitive touch detection.
3Adaptability or versatility
If complex trace patterns are used to enhance multi-touch capabilities, then production complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the sensor grid into repeating unit cells or modular trace pattern blocks. Each module contains a complete set of trace patterns that can be tiled across the entire sensor surface, enabling complex multi-touch functionality through simple repetition rather than unique complex patterns throughout, thereby reducing production complexity.
Solution Approach 2:
The patent employs universal trace pattern designs that serve multiple functions simultaneously: the same trace configuration supports both single-touch and multi-touch detection, provides both capacitive sensing and visual appearance functions, and works across different sensor sizes and resolutions. This multi-functionality reduces the need for specialized complex patterns for each application scenario.
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
This design reduces visual interference and production time while maintaining high sensitivity for multi-touch detection, offering a balanced solution for both production efficiency and user experience.
Implementation Method 1
Projected Capacitive Technology (PCT) is becoming one of the most significant touch technologies... PCT refers to two main sensing methods called 'self-capacitance' and 'mutual capacitance'
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A capacitive touch sensor is described. The touch sensor includes a sensor grid that includes a trace that has a trace start point and end point, is electrically conductive between the trace start point and the trace end point, is formed in one or more pairs of trace cells that each include a first trace cell and a second trace cell that is rotationally symmetrical to the first trace cell. The trace start point and the trace end point define a trace axis. A trace direction is defined from the trace start point to the trace end point. A trace-perpendicular direction is defined as being perpendicular to the trace direction. A segment of the trace that is formed in the first trace cell includes a first portion, a second portion, a third portion, a fourth portion, a fifth portion, a sixth portion, a seventh portion, and an eighth portion.