Capacitive Sensing Feed-Line Compensation for Parasitic Coupling
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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 capacitive coupling by adjusting signals from existing 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 feed lines are used to connect electrodes with electronic circuit, then electrical connection is established, but unwanted capacitive coupling is introduced
Solution Approach 1:
The patent introduces dummy feed lines as intermediary elements that replicate the capacitive coupling effects of actual feed lines. These dummy lines serve as mediators to measure and compensate for parasitic coupling without being directly connected to sensing electrodes, thereby isolating the harmful effect measurement from the sensing function.
Solution Approach 2:
The system implements feedback by using the signals from dummy feed lines to adjust and compensate for parasitic coupling effects in the actual electrode signals. The compensation mechanism continuously monitors the capacitive coupling through dummy lines and applies corrective adjustments to maintain signal accuracy.
2Measurement precision
If additional dummy feed lines are added for compensation, then signal accuracy is improved, but device complexity increases
Solution Approach 1:
The patent creates simplified copies of the actual feed lines in the form of dummy feed lines that replicate their capacitive coupling characteristics. These copies allow measurement and compensation of parasitic effects without requiring complex modeling or calculation, reducing computational complexity while improving measurement precision.
3Reliability
If feed lines are routed in parallel with electrodes, then capacitive coupling is minimized, but routing complexity increases
Solution Approach 1:
Instead of directly routing feed lines parallel to electrodes, the patent uses dummy feed lines as intermediaries that are routed parallel to the actual feed lines. This indirect approach achieves the same capacitive coupling replication without the complexity of precise parallel routing between electrodes and feed lines.
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 coupling, improving signal accuracy and system performance by reducing the influence of feeding lines on measurement data, allowing for precise object positioning and gesture detection in three-dimensional spaces.
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.