Capacitive Sensor Electrode Switching for Interference Tolerance
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Solution Overview
Problem
Capacitive sensor devices are susceptible to interference, with each sensor arrangement having its own unique sensitivity profile and susceptibility to faults, which affects detection accuracy and reliability.
Innovation Solution
The sensor device employs a control and evaluation circuit that dynamically switches electrode configurations, acquiring and combining individual signals from different electrode functions to reduce interference by ensuring consistency across multiple detections, thereby forming a robust overall sensor signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single electrode configuration is used for capacitive sensing, then the device structure is simple, but the susceptibility to interference is high and detection reliability is reduced
Solution Approach 1:
The patent divides the sensing function into multiple electrode configurations, where each configuration segment (sensor electrode, shield electrode, reference electrode) performs a specific function. By segmenting the electrode roles and switching between different configurations, the system achieves higher reliability through diversity while managing complexity through structured control.
Solution Approach 2:
The patent implements dynamic switching between different electrode configurations based on detection needs. The control unit dynamically assigns different electrodes to different functions (sensor, shield, reference) in different time periods, allowing the system to adapt to varying interference conditions and improve detection reliability dynamically.
2Reliability
If multiple electrode configurations are used to reduce interference, then detection reliability improves, but the control and evaluation circuit complexity increases
Solution Approach 1:
The patent makes electrodes multi-functional by allowing them to serve different roles (sensor electrode, shield electrode, reference electrode) depending on the active configuration. This universality reduces the need for separate dedicated electrodes for each function, improving interference tolerance while limiting circuit complexity growth.
Solution Approach 2:
The control unit periodically switches between different electrode configurations in a systematic manner, evaluating signals from multiple configurations over time. This periodic action allows the system to gather diverse detection data while maintaining manageable control complexity through structured, repeating patterns.
3Object-affected harmful factors
If electrodes are dynamically switched between different functions, then interference susceptibility is reduced, but the detection time increases due to multiple measurements
Solution Approach 1:
The patent evaluates signals from multiple electrode configurations, but not all configurations need to be fully evaluated in every detection cycle. The control unit can selectively evaluate signals based on interference conditions, performing partial evaluations when interference is low and more comprehensive evaluations when interference is high, thus reducing average detection time while maintaining interference tolerance.
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 significantly reduces the overall susceptibility to interference and fault tolerance by averaging out individual electrode configuration vulnerabilities, enhancing detection reliability and accuracy.
Implementation Method 1
Capacitive sensor devices are known in the field of technology, particularly in automotive engineering. For example, DE 10 2014 107 559 A1 discloses a sensor device for a motor vehicle. Capacitive sensors have one or more electrodes that are sensitive to capacitance changes.
Data Source
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AI summary
A sensor device for the capacitive detection of approaches or touches by a user (5), wherein the sensor device comprises a plurality of electrodes (2, 3, 4), which are galvanically separated, mutually spaced and arranged one above the other in a plurality of layers. The electrodes (2, 3, 4) are coupled to at least one control and evaluation circuit (1), which controls the electrodes in successive time periods to execute changing functions such that the electrodes form a capacitive sensor array having a temporally variable electrode assignment. To detect an actuation, the control and evaluation circuit (1) controls the electrodes (2, 3, 4) in succession with at least two different electrode assignments, wherein at least one separate signal is detected for each electrode assignment and the control and evaluation circuit evaluates the plurality of separately detected signals and detects an actuation in accordance with all the separately detected signals.