Capacitive Fill Level Sensor with Segmented Electrodes
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Solution Overview
Problem
Existing non-invasive capacitive level measurement methods are susceptible to external interference and require precise calibration, leading to measurement inaccuracies and user-friendliness issues, especially in environments with high-frequency voltage sources and multiple apparatuses.
Innovation Solution
A non-contact capacitive level measurement device with multiple measuring electrodes and a reference electrode, where the electric fields penetrate the container wall, allowing for accurate fill level determination by relating the capacitances of multiple capacitors formed between the electrodes, and an evaluation device processes these measurements to minimize external influence effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-invasive capacitive level measurement is used, then contact with liquid is avoided preventing contamination, but measurement accuracy deteriorates due to external interference from high-frequency voltage sources and other apparatuses
Solution Approach 1:
The measuring electrode is divided into multiple segments arranged vertically along the container wall. Each segment independently measures capacitance in its specific region, allowing the system to identify and exclude segments affected by external interference while maintaining accurate measurements from unaffected segments.
Solution Approach 2:
The system continuously monitors capacitance measurements from all electrode segments and uses evaluation logic to detect anomalies caused by external interference. When interference is detected in specific segments, the evaluation device adjusts the measurement by excluding or weighting affected segments differently, providing feedback-based compensation for maintain accuracy.
2Measurement precision
If precise calibration is performed to improve measurement accuracy, then measurement precision improves, but device complexity and user-friendliness worsen due to calibration dependency
Solution Approach 1:
The system performs automatic self-calibration by analyzing the capacitance patterns from multiple electrode segments and automatically compensating for external interference effects. The evaluation device independently determines which segments are affected and adjusts measurements without requiring user intervention or manual calibration procedures.
Solution Approach 2:
The system dynamically changes measurement parameters by selectively weighting or excluding specific electrode segments based on real-time interference detection. Instead of fixed calibration values, the system adapts its measurement approach by modifying which segments contribute to the final fill level calculation, eliminating the need for manual calibration.
3Reliability
If multiple measuring electrodes are used to reduce external interference, then measurement reliability improves, but device complexity increases
Solution Approach 1:
The multiple electrode segments serve dual functions: each segment acts as both a measurement element for its specific region and as an interference detection element for the entire system. The same physical structure used for measurement also provides the data needed to identify and compensate for external interference, eliminating the need for separate calibration mechanisms.
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 device significantly reduces measurement distortions from external interference and minimizes calibration dependency, providing robust and accurate fill level measurements across various media and container types.
Implementation Method 1
capacitive level measurement methods. These methods are characterized by the fact that no part of the level sensor comes into contact with the medium whose fill level is to be determined. The active area of a capacitive sensor contains electrodes that detect the dielectric properties of its surroundings.
Implementation Method 2
In capacitive level measurement, the different dielectric conductivity ε of the material being filled compared to gases or air is utilized. The capacitance of a capacitor depends on the permittivity of the packing material.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
The device (100) has measuring electrodes (103-112) arranged in different horizontal planes, where the measuring electrodes define a measurement surface with a vertical extent. A reference electrode (113) defines a reference surface with the vertical extent. The measuring electrodes form capacitors together with the reference electrode, so that an electric field is formed, where the vertical extent of the reference surface corresponds to the vertical extent of the measurement surface. An independent claim is also included for a method for non-invasive capacitive measuring a liquid level of a filling medium in a container.