Capacitive Sensing Feed Line Layout for Coupling Compensation
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Solution Overview
Problem
Capacitive sensing systems face issues with unwanted capacitive coupling between target objects and feeding lines, leading to inaccurate signal processing and decreased system performance, especially when shielding is not practical.
Innovation Solution
The implementation of additional feed lines that operate as electrodes or dummy lines to compensate for parasitic coupling effects by adjusting signals received from electrodes, using either analog or digital circuitry to correct measurement values, and routing feed lines in parallel or vicinity to electrodes to minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feeding lines are used to connect electrodes with electronic circuit, then electrical connection is established, but parasitic capacitive coupling occurs causing measurement errors
Solution Approach 1:
The patent introduces additional feed lines as intermediary elements that act as dummy electrodes to compensate for the parasitic coupling effects. These intermediary feed lines are strategically positioned to detect and counterbalance the unwanted capacitive coupling between the target object and the signal-carrying feed lines, thereby restoring measurement accuracy without requiring shielding.
Solution Approach 2:
The patent extracts and separates the harmful parasitic coupling effect from the useful signal by using dedicated compensation feed lines. These extracted compensation signals are then processed independently to cancel out the unwanted coupling effects from the main measurement signals, allowing the useful information to be preserved while removing the harmful interference.
2Measurement precision
If additional feed lines are added for compensation, then parasitic coupling is reduced, but device complexity increases
Solution Approach 1:
The additional feed lines serve multiple functions: they act as dummy electrodes for compensation, provide reference signals for cancellation algorithms, and can be integrated into the existing electrode array design. This multi-functionality allows the system to achieve compensation without adding separate dedicated components, thereby limiting the increase in overall device complexity.
3Reliability
If feed lines are routed in parallel with electrodes, then parasitic coupling is minimized, but routing complexity increases
Solution Approach 1:
The patent merges the compensation function with the existing feed line structure by routing additional feed lines in parallel with the signal-carrying feed lines. This merging approach allows both the signal transmission and parasitic coupling compensation functions to be achieved within the same routing infrastructure, reducing the need for separate complex routing paths while maintaining signal integrity.
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 approach effectively compensates for parasitic capacitive coupling, improving signal accuracy and system performance by reducing the influence of feeding lines on measurement values, even in unshielded configurations, thereby enhancing the reliability of capacitive sensing systems.
Implementation Method 1
The feeding lines between the integrated circuit and the electrodes may cause unwanted additional capacitive coupling in such a system
Data Source
AI summary
An input device has one or more electrodes configured for capacitive sensing, an electronic circuit, one or more conductive feed line(s) connecting the one or more electrode(s) with the electronic circuit, wherein the device is configured to increase or decrease a signal received from at least one of the electrodes through an associated feed line in function of at least one other signal from another electrode.