Capacitive Rotation Sensor Using Pulsed Excitation
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Solution Overview
Problem
Existing rotation detection methods using light or magnetic scanning face interference from external factors, leading to complex and costly signal compensation, and capacitive methods suffer from low signal strength and high power consumption.
Innovation Solution
A capacitive rotation detection arrangement with a conductive partial surface on a rotating element, utilizing a high-voltage pulse applied to a planar excitation electrode and received by multiple planar receiver electrodes, which compares signals to determine the rotation position, enhancing signal strength and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light or magnetic scanning methods are used for rotation detection, then the arrangement can detect rotation, but the detection is influenced by external interference factors (light, external magnets) and requires complex signal compensation
Solution Approach 1:
The patent replaces optical and magnetic detection systems with a capacitive sensing system that uses electrical fields instead of light or magnetic fields. This substitution eliminates sensitivity to external light and magnetic interference while maintaining rotation detection capability through capacitive coupling between the rotating element and sensor electrodes.
Solution Approach 2:
The patent changes the detection parameter from optical/magnetic properties to capacitive properties. By measuring changes in capacitance caused by the rotating element's movement relative to the sensor, the system achieves interference-free detection without requiring complex compensation mechanisms for external disturbances.
2Object-affected harmful factors
If capacitive measuring methods are used with conventional voltage pulses, then external magnetic fields and light do not influence the detection, but the useful signal received is relatively small requiring complex comparator adjustment
Solution Approach 1:
The patent employs periodic voltage pulses applied to the excitation electrode rather than continuous voltage. This pulsed excitation method generates time-varying capacitive coupling signals that are significantly stronger and easier to detect, while the periodic nature allows for synchronized sampling and further signal processing optimization.
Solution Approach 2:
The patent changes the voltage parameter by applying high-voltage pulses (significantly higher than the operating battery voltage) to the excitation electrode. This parameter change amplifies the capacitive coupling effect, generating stronger receiver signals that exceed comparator offset issues and eliminate the need for complex adjustment mechanisms.
3Measurement precision
If high voltage pulses are applied to the excitation electrode, then the useful signal produced is significantly larger, but power consumption increases
Solution Approach 1:
The patent uses periodic voltage pulses instead of continuous high voltage, confining high power consumption to brief pulse durations. The majority of the time, the system operates at low power during signal evaluation and between pulses, achieving overall low power consumption while maintaining strong signal generation during active measurement periods.
Solution Approach 2:
The patent maintains continuous rotation detection capability through periodic sampling rather than requiring continuous high-power operation. The system achieves effective continuous monitoring by strategically timed pulses that capture rotation information at sufficient intervals, eliminating the need for continuous energy expenditure.
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 provides a significantly stronger useful signal with lower power consumption, simplifying circuitry and reducing costs, while effectively detecting rotation independent of external interference.
Implementation Method 1
the electrically conductive partial surface can be capacitively coupled to the excitation electrode and with at least two planar receiver electrodes adjacent to the excitation electrode
Data Source
Figure 1~5
Figure 6~9
Figure 10~11
AI summary
The arrangement has an electrically conducting partial surface provided on a plane surface of rotating units. Fixed sensor units have excitation electrodes (4) and receiver electrodes (8a, 8b) that are adjacent to the excitation electrodes. The electrodes stay at a distance opposite to the partial surface. The receiver electrodes and the partial surface are designed in a form of thinner metallic layers. The receiver electrodes are capacitvely coupled with the excitation electrodes during rotation of rotating units by the partial surface.