Magnetic Sensor Interference Offset via Time-Division Multiplexing
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Solution Overview
Problem
Magnetic interference in magnetic sensors hinders accurate detection of external forces and displacements due to the need for additional stationary magnetoelectric conversion elements, which restricts sensor miniaturization and freedom in design, and complicates the removal of interference effects.
Innovation Solution
A magnetic sensing system that generates a variable measurement magnetic field, allowing for the calculation of physical quantities associated with external forces by using a relational expression to specify and offset magnetic interference, eliminating the need for separate interference measurement sensors and enabling compact sensor design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a stationary magnetoelectric conversion element is added to detect magnetic interference, then measurement accuracy is improved, but device complexity increases and miniaturization is hindered
Solution Approach 1:
The patent combines the magnetic interference detection function with the existing displaced magnetoelectric conversion element by having it perform dual functions: detecting both the measurement magnetic field and the interference magnetic field at different time points. This eliminates the need for a separate stationary magnetoelectric conversion element, thereby reducing device complexity while maintaining measurement accuracy.
Solution Approach 2:
The patent employs periodic action by alternately generating the measurement magnetic field and the interference magnetic field at different time points. The magnetoelectric conversion element periodically switches between detecting the measurement field (when the permanent magnet is in its initial position) and detecting the interference field (when the permanent magnet is displaced). This time-division multiplexing approach allows one element to perform the work of what would traditionally require two elements.
2Measurement precision
If a stationary magnetoelectric conversion element is added to detect magnetic interference, then measurement accuracy is improved, but the sensor size increases
Solution Approach 1:
The patent merges the interference detection capability into the existing displaced magnetoelectric conversion element, eliminating the need for an additional stationary element. This consolidation maintains measurement accuracy while significantly reducing the overall sensor volume and enabling miniaturization.
3Device complexity
If the stationary magnetoelectric conversion element is placed at a distant position, then device complexity is reduced, but measurement accuracy deteriorates
Solution Approach 1:
The patent uses periodic action to have the single magnetoelectric conversion element detect both the measurement magnetic field and the interference magnetic field at different time points. By alternately generating these fields and having the element respond to each, the system achieves accurate interference cancellation without requiring the element to be positioned at a specific distant location, thus maintaining both simplicity and accuracy.
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 allows for accurate detection of external forces and displacements by reliably removing magnetic interference, facilitating compact sensor configurations and improved measurement accuracy without additional interference measurement sensors.
Implementation Method 1
a displaced magnetoelectric conversion element disposed facing the magnet at a predetermined distance from the surface on one side of the magnet and configured to be displaced in response to the action of an external force to thereby detect a magnetic field change occurring because of the external force
Implementation Method 2
a permanent magnet affixed to the displacement unit, and a magnetic sensor that detects the state of a measurement magnetic field generated by the permanent magnet
Data Source
AI summary
A magnetic sensing system 10 according to the present invention is provided with a sensing device 11 that generates an electrical signal according to the strength of a magnetic field that changes in response to the action of an external force, and a detection device 12 that detects a physical quantity associated with the action of the external force from a change in the magnetic field based on the electrical signal from the sensing device 11. The sensing device 11 includes magnetic field generation means 15 and 18 that generate a desired measurement magnetic field of different strengths from a site that is displaced by the action of the external force, and a magnetic field measurement means 19 that measures the strength of a surrounding magnetic field including the measurement magnetic field. The detection device 12 uses a relational expression stored in advance to specify, on the basis of fluctuations over time in the measurement magnetic field of different strengths, a magnetic interference amount corresponding to the strength of an interference magnetic field generated separately from the measurement magnetic field, and calculates the physical quantity by removing the influence of the magnetic interference amount.