An apparatus for sensing liquid level, a device using the said apparatus, and a calibration method
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Solution Overview
Problem
Existing technologies for sensing liquid levels in containers are limited as they require special container shapes, are not suitable for different materials or thicknesses, and can't accurately detect levels at multiple points, leading to potential malfunctions in appliances like hot beverage brewing machines.
Innovation Solution
A contactless liquid level sensing apparatus using multiple plates with a control unit to calculate capacitance changes, including a calibration part with air on both sides for self-calibration, allowing accurate level detection across various container materials and thicknesses without modifying the container's shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive sensing plates are used to detect liquid level, then liquid level can be sensed, but the measurement is affected by container material and thickness causing inconsistent readings
Solution Approach 1:
The system performs self-calibration by automatically measuring the capacitance of each plate when the container is empty and using these measurements to calculate compensation factors. This self-service approach eliminates the need for manual calibration and enables the system to adapt to different container materials and thicknesses automatically, resolving the contradiction between measurement precision and adaptability.
Solution Approach 2:
The system changes the operational parameters by measuring capacitance at different states (empty and full) and using these parameter variations to calculate compensation factors. By utilizing parameter changes during calibration, the system adapts to specific container characteristics and maintains accurate measurements across different container types.
2Measurement precision
If multiple plates are used for sensing at different levels, then multiple level detection is achieved, but the device complexity increases
Solution Approach 1:
The system merges the calibration process with the normal operation by using the same capacitance measurement mechanism for both calibration and level detection. The compensation factors calculated during calibration are integrated into the measurement algorithm, allowing multi-level detection without requiring separate calibration hardware or complex additional components.
Solution Approach 2:
The system performs automatic self-calibration without requiring external intervention or complex calibration procedures. By automatically measuring empty and full states and computing compensation factors, the system reduces device complexity while maintaining accurate multi-level detection capability.
3Measurement precision
If calibration is performed for each container type, then measurement accuracy is maintained, but the time and process complexity increases
Solution Approach 1:
The system performs automatic self-calibration by measuring the capacitance of each plate when the container is empty and when it is full, then automatically calculating compensation factors. This self-service calibration process eliminates manual intervention, reduces calibration time, and maintains measurement accuracy across different container types without increasing process complexity.
Solution Approach 2:
The system performs calibration measurements (empty and full states) as preliminary actions before normal operation begins. By completing the calibration process in advance, the system establishes compensation factors that will be used during subsequent measurements, ensuring accuracy without requiring repeated calibration steps during operation.
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
Enables accurate and consistent liquid level sensing at multiple levels, independent of container shape and material, ensuring reliable operation in appliances by compensating for measurement deviations and maintaining sensitivity.
Implementation Method 1
a contactless liquid level sensing apparatus using multiple plates with a control unit to calculate capacitance changes
Data Source
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AI summary
The present invention relates to an apparatus (1) for detecting the liquid level in a container (10) characterized by, at least one plate (2) for every level to be sensed on the container (10), and at least one control unit (3) adapted to send electrical signals to the plates (2), and calculate the change in the capacitance of the said plates (2) according to the changes in the said electrical signals, a device (100) in which this apparatus (1) is used, and a calibration method.