Magnetic Field Converter for Sensor Stability
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Solution Overview
Problem
Magnetic sensor devices face challenges in maintaining detection accuracy due to variations in the gap between the magnet and the magnetoresistive effect element, leading to noise and sensitivity fluctuations, which conventional bias electric current adjustments cannot fully control.
Innovation Solution
A magnetic sensor device incorporating a magnetic field converter that converts input magnetic fields orthogonal to the sensor's sensitive direction, a magnetic field detector, and a magnetic shield to shield external fields, ensuring the magnetic field transmittance is within 1-30% and the gap length is optimized to improve signal linearity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gap between the magnet and the magnetoresistive effect element is reduced to increase magnetic field strength, then detection sensitivity is improved, but manufacturing precision becomes more difficult to control and noise increases
Solution Approach 1:
A magnetic field converter made of soft magnetic material is introduced as an intermediary between the magnet and the magnetoresistive effect element. This converter concentrates and guides the magnetic field lines, enabling the sensor to detect perpendicular magnetic field components while maintaining a larger gap. The converter acts as a mediator that transforms the magnetic field distribution without requiring precise gap control.
Solution Approach 2:
The invention changes the operational parameters by using a magnetic field converter with specific magnetic permeability properties to transform the magnetic field orientation. By converting the perpendicular magnetic field component into a detectable form, the system achieves high sensitivity without requiring the gap to be minimized, thus decoupling sensitivity from gap precision requirements.
2Reliability
If bias electric current is increased to compensate for gap variations, then sensitivity fluctuations are reduced, but device complexity increases and adjustment range is limited
Solution Approach 1:
The magnetic field converter is pre-configured with optimized geometry and magnetic properties to automatically compensate for gap variations. By designing the converter's shape and material characteristics in advance, the system achieves sensitivity stability without requiring complex real-time adjustments through driver IC control, thus reducing device complexity while maintaining reliability.
3Measurement precision
If the magnetic field converter dimensions are increased to improve field conversion, then detection accuracy is improved, but device volume increases
Solution Approach 1:
The magnetic field converter utilizes soft magnetic material with high magnetic permeability to achieve effective field conversion in a compact form. The composite structure of the converter, optimized for magnetic flux concentration, enables high detection accuracy without requiring large dimensions, thus maintaining small device volume while improving measurement precision.
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 enhances detection accuracy by stabilizing the magnetic field strength and reducing sensitivity fluctuations, even with variations in the gap length, thereby improving the overall performance of the magnetic sensor device.
Implementation Method 1
This soft magnetic material converts the perpendicular magnetic field component in a direction perpendicular to the substrate surface, of the components of the magnetic field generated by the magnet, into a magnetic field component that is parallel to the substrate surface
Implementation Method 2
a magnetoresistive effect element (GMR element, TMR element or the like) in which resistance changes in accordance with change in the external magnetic field
Data Source
AI summary
A magnetic sensor device includes a magnetic field converter that receives an input magnetic field input along a first direction and outputs an output magnetic field along a second direction, which is orthogonal to the first direction. A magnetic field detector is provided at a position where the output magnetic field is applied. A magnetic shield shields external magnetic fields along a third direction, which is orthogonal to both the first direction and the second direction. When viewed along the first direction, the magnetic field converter has a shape such that the length in the third direction is greater than the length in the second direction. When viewed along the first direction, the magnetic shield is provided at a position overlapping the magnetic field converter and the magnetic field detector, and the magnetic field transmittance of the external magnetic field is 1˜30%.