Capacitive Sensor Coil for Steering Wheel Drift Reduction
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Solution Overview
Problem
Capacitive sensor devices for detecting human body parts, such as hands on a steering wheel, are prone to drift due to environmental factors like temperature and humidity, requiring complex and costly measurement apparatus to compensate for these disturbances.
Innovation Solution
A capacitive sensor device with an electrical coil that generates a measurement variable based on the current difference between two sensor electrodes, eliminating the need for complex difference formation circuits and allowing for simple compensation of systematic deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If individual currents are measured and then used to determine current difference, then drift is reduced, but measuring apparatus becomes complex and costly
Solution Approach 1:
The patent combines the current difference determination function directly into the coil structure itself, eliminating the need for separate complex difference formation circuits. The coil is designed to directly generate a measurement variable based on the current difference between the two sensor electrodes, merging the measurement and signal generation functions into a single integrated component.
Solution Approach 2:
The patent replaces complex electronic difference formation circuits with an electromagnetic coil-based measurement system. Instead of using complex electrical circuitry to calculate current differences, the system uses electromagnetic induction through a coil to directly sense and generate a measurement variable proportional to the current difference, simplifying the overall system architecture.
2Measurement precision
If complex difference formation circuits are used, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces complex electronic difference formation circuits with an electromagnetic coil-based measurement system. The coil directly generates a measurement variable based on the current difference, eliminating the need for multiple circuit components and simplifying the system while maintaining measurement accuracy.
Solution Approach 2:
The coil structure itself performs the measurement function by directly generating a measurement variable from the current difference. The system is self-sufficient, with the coil automatically sensing and converting the current difference into a measurable signal without requiring external complex circuitry to process the measurement.
3Reliability
If more components are added to compensate for disturbances, then measurement reliability is improved, but installation space increases
Solution Approach 1:
The patent merges the disturbance compensation function into the existing coil structure and evaluation apparatus. By determining the current difference directly through the coil's measurement variable, the system eliminates the need for separate compensation components, achieving reliable measurements while minimizing the overall device footprint.
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
The solution reduces the number of components, saves installation space, and provides accurate 'hands on-off detection' by minimizing systematic deviations, resulting in a simpler, lighter, and more cost-effective sensor device.
Implementation Method 1
an electrical coil having at least one winding, the coil being designed in such a manner and the first electrode section of the at least one first sensor electrode and the second electrode section of the second sensor electrode, at least in sections, being arranged in each case relative to one another in such a manner and in each case relative to the coil in such a manner and being coupled to the coil in such a manner that a measurement variable dependent on a current difference between a first current flowing in the first electrode section and a second current flowing in the second electrode section is generable or is generated in the coil by means of the current difference
Data Source
AI summary
A capacitive sensor device for detecting the presence of a human body part in a detection region of the sensor device is disclosed. The sensor device includes a first sensor electrode with a first electrode section, a second sensor electrode with a second electrode section, and a measuring device for ascertaining a measurement variable, which is based on a current difference between a first current flowing in the first electrode section of the at least one first sensor electrode and a second current flowing in the second electrode section of the second sensor electrode. The measuring device has an electric coil, and the first electrode section of the first sensor electrode and the second electrode section of the second sensor electrode are at least partly arranged relative to each other and relative to the coil in each case and are coupled to the coil.