Magnetic Sensor with Integrated Solenoid for Noise Reduction
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Solution Overview
Problem
Magnetic sensors face challenges in maintaining sensitivity and accuracy due to environmental noise and stray magnetic fields, and they often require recalibration, especially in applications where size and manufacturability are critical.
Innovation Solution
The design incorporates a magnetic sensor device with a substrate and solenoids where the total length of the closed magnetic circuit is at least twice the length of the gaps, allowing magnetic flux to pass through magnetic cores more than outside them, reducing susceptibility to noise and enabling recalibration by controlling current through the solenoids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If magnetic sensors are integrated with electronic processing circuitry to reduce size, then device size is reduced, but susceptibility to environmental noise and stray magnetic fields increases
Solution Approach 1:
The magnetic circuit is segmented into distinct components: magnetic cores, gaps, and magnetic sensors positioned at specific locations. This segmentation allows the sensor to be integrated close to the magnetic circuit while maintaining controlled magnetic flux paths that reduce noise susceptibility.
Solution Approach 2:
Magnetic cores serve as intermediaries that guide and concentrate magnetic flux between the excitation source and the sensor. These cores create defined magnetic pathways that isolate the sensor from external magnetic interference while maintaining sensitivity to target magnetic fields.
2Measurement precision
If magnetic flux passes through gaps in the magnetic circuit, then magnetic field detection is enabled, but measurements drift over time due to varying sensitivity and offset
Solution Approach 1:
A recalibration mechanism is implemented that allows preliminary adjustment of magnetic flux through the gaps before actual measurement. By controlling current through solenoids to impose magnetic fields on the sensor, offset and sensitivity drift can be compensated for in advance, improving measurement reliability.
Solution Approach 2:
The magnetic circuit design enables feedback-based recalibration where the sensor measurements are used to adjust the magnetic flux through the gaps. This closed-loop approach compensates for drift by actively adjusting the magnetic field to maintain accurate measurements over time.
3Measurement precision
If ferromagnetic cores are used to increase magnetic flux density, then sensitivity is improved, but manufacturing complexity increases
Solution Approach 1:
Multiple magnetic cores and gaps are merged into an integrated magnetic circuit structure that can be manufactured as a single assembly. This combining of components simplifies manufacturing while maintaining the high magnetic flux density provided by ferromagnetic materials.
Solution Approach 2:
The magnetic cores serve multiple functions: they concentrate magnetic flux to improve sensitivity, provide structural support for the integrated design, and enable recalibration by controlling flux distribution. This multi-functionality reduces the need for separate components, simplifying manufacturing.
4Measurement precision
If solenoids are integrated with magnetic sensors for recalibration, then measurement accuracy is improved, but device complexity increases
Solution Approach 1:
Solenoids are merged with the magnetic sensor assembly, with coils wound around or near the magnetic cores. This integration allows recalibration functionality to be built into the sensor structure itself, improving accuracy while minimizing the increase in device complexity through shared components and compact arrangement.
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 configuration enhances the sensitivity and accuracy of magnetic sensors, reduces their susceptibility to environmental noise, and allows for effective recalibration, improving their performance in diverse environmental conditions.
Implementation Method 1
By applying an electrical current to the solenoid, a magnetic field is formed. The one or more coils are configured for, when a current passes through said one or more coils, generating a magnetic field wherein at least a portion of the generated magnetic flux passes through at least a portion of the magnetic sensor, of the cores, and of the gaps forming at least one closed magnetic circuit
Implementation Method 2
The use of a ferromagnetic core increases the magnitude of the magnetic flux density in the solenoid, concentrating the magnetic field
Implementation Method 3
Magnetic sensors can incorporate Hall effect sensors that generate an output voltage proportional to an applied magnetic field
Implementation Method 4
magneto-resistive materials whose electrical resistance changes in response to an external magnetic field
Data Source
Figure 1A~1C
Figure 2A~3A
Figure 3B~4A
AI summary
A magnetic sensor device (99) comprises a substrate (10) having a surface and a magnetic sensor (30) that detects magnetic fields disposed on, over, below, or in direct contact with the surface. One or more magnetic cores (22) are disposed on or over the substrate surface, at least one of the magnetic cores (22) having an electrical conductor (24) helically wound around the core (22) forming a coil (25) having a coil length. Each magnetic core (22) is separated from any other magnetic core by a gap (G) having a gap length. A current passing through the one or more coils (25) generates a magnetic field at least a portion of whose magnetic flux passes through at least a portion of the magnetic sensor, one or more coils (25), and one or more gaps (G). The sum of the coil lengths is greater than the sum of the gap lengths through which the at least a portion of the magnetic flux passes.