Noise Immunity for Capacitive Sensors via Oscillation Analysis
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Solution Overview
Problem
Existing touch, proximity, and gesture detection systems using Capacitive Voltage Division (CVD) are prone to noise interference, leading to inaccurate capacitance and impedance measurements.
Innovation Solution
A sensor system with a receiver circuit and transmitter electrode that oscillates when capacitance reaches a threshold, allowing control logic to determine the amplitude and frequency of the transmitter output signal, identifying noise presence and taking corrective actions such as filtering or adjusting thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage parameter is used to determine impedance on receiver port, then capacitance or impedance can be determined, but noise interference occurs leading to inaccurate measurements
Solution Approach 1:
The patent introduces an oscillation detection mechanism as an intermediary between the voltage parameter and the capacitance measurement result. The receiver circuit oscillates when capacitance reaches a threshold, and this oscillation state serves as a mediator to confirm valid measurements. The control logic analyzes oscillation characteristics (amplitude, frequency) to distinguish true capacitance changes from noise, thereby improving measurement accuracy while filtering out harmful noise interference.
2Extent of automation
If receiver circuit oscillates when capacitance reaches threshold, then automatic triggering occurs, but noise may cause false oscillation and incorrect measurements
Solution Approach 1:
The patent implements feedback through oscillation detection and analysis. When the receiver circuit oscillates, the control logic monitors the oscillation characteristics (amplitude and frequency) and compares them against expected ranges. This feedback mechanism allows the system to distinguish between legitimate capacitance-triggered oscillations and noise-induced false oscillations, thereby maintaining automatic triggering capability while improving measurement reliability.
Solution Approach 2:
The patent applies dynamics by making the transmitter electrode activation conditional and adaptive. Instead of continuous operation, the transmitter is activated only when oscillation is detected and validated through amplitude and frequency analysis. This dynamic approach allows the system to adapt its operation based on real-time conditions, enabling automatic triggering while filtering out noise through conditional activation.
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
Enhances the accuracy of touch, proximity, and gesture detection by mitigating noise interference, ensuring reliable capacitance and impedance measurements.
Implementation Method 1
The receiver circuit may be configured to oscillate when a capacitance measurement reaches a capacitance threshold. The capacitance measurement may include capacitance between the receiver electrode and the transmitter electrode.
Data Source
AI summary
A sensor system includes a receiver circuit including a receiver electrode, a transmitter electrode, and control logic. The control logic is configured to determine that an amplitude of a transmitter electrode output signal is greater than an amplitude threshold. Based on this determination, the control logic is configured to whether a frequency of the transmitter electrode output signal is within an allowed frequency range. Based on a determination that the frequency of the transmitter electrode output signal is not within the allowed frequency range, the control logic is configured to determine that noise is present in the system.