Magnetic Particle Field Conversion for Accurate 3-Axis Sensing
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Solution Overview
Problem
Existing 3-axis magnetic sensors face issues with inaccuracy and reproducibility due to magnetic hysteresis in soft magnetic materials, uneven sensor responses, and difficulty in securing sensor alignment, particularly in detecting Z-axis magnetic fields.
Innovation Solution
A three-axis magnetic field detection device using a magnetic field conversion unit based on magnetic particles to generate a stray field, allowing detection of X, Y, and Z-axis magnetic fields through a magnetic sensor, with the ability to freely determine sensor positions via photolithography and heat treatment processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a soft magnetic permalloy plate is used as a magnetic field converter, then magnetic field direction conversion is achieved, but magnetic hysteresis occurs resulting in inaccurate magnetic field conversion rates
Solution Approach 1:
The patent changes the material parameter from soft magnetic permalloy plate to magnetic particles suspended in adhesive resin. This material parameter change eliminates magnetic hysteresis while maintaining magnetic field conversion capability, directly resolving the contradiction between conversion accuracy and reliability.
Solution Approach 2:
The patent uses a composite structure of magnetic particles mixed with adhesive resin to create the magnetic field converter. This composite material approach combines the magnetic properties of particles with the binding properties of resin, achieving accurate magnetic field conversion without hysteresis losses.
2Ease of manufacture
If electroplating or adhesive resin is used to manufacture magnetic field converter, then magnetic field conversion is enabled, but position accuracy is reduced resulting in poor manufacturing reproducibility
Solution Approach 1:
The patent uses photolithography to create a mold that copies the desired magnetic field converter pattern, then transfers this pattern to the substrate using the adhesive resin mixture. This copying process ensures high position accuracy and manufacturing reproducibility while maintaining ease of fabrication.
Solution Approach 2:
The patent replaces traditional mechanical alignment methods with photolithographic patterning to determine the position of the magnetic field converter. This substitution of mechanical positioning with optical patterning significantly improves manufacturing precision while maintaining ease of manufacture.
3Adaptability or versatility
If three magnetic sensors are perpendicularly coupled to detect specific axis magnetic fields, then three-axis detection capability is achieved, but reproducibility and accuracy are difficult to secure with uneven sensor responses
Solution Approach 1:
The patent makes a single magnetic sensor universal by using the magnetic field converter to redirect magnetic fields from all three axes to the sensor's detection direction. The converter adapts the magnetic field orientation based on the external field direction, allowing one sensor to perform three-axis detection with uniform response characteristics.
4Adaptability or versatility
If sensor is fabricated on tilted wafer using wet etching process, then three-axis magnetic field detection is achieved, but design complexity increases due to inclined plane sensor characteristics
Solution Approach 1:
The patent introduces the magnetic field converter as an intermediary component between the external magnetic field and the magnetic sensor. This mediator redirects the magnetic field from different axes to the sensor's detection direction, eliminating the need for complex tilted wafer fabrication and simplifying the overall device design.
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
Improves reproducibility and accuracy in detecting three-axis magnetic fields by generating a stray field with a magnetic field direction according to the outer magnetic field, enabling precise detection of Z-axis fields without magnetic hysteresis and sensor misalignment.
Implementation Method 1
a magnetic field conversion unit for generating a stray field having a magnetic field direction according to a magnetic field direction of an outer magnetic field using magnetic particles
Implementation Method 2
a magnetic field measurement unit for measuring magnetic field directions for an X-axis magnetic field, a Y-axis magnetic field and the stray field
Data Source
AI summary
A three-axis magnetic field detection device includes a magnetic field conversion unit for generating a stray field having a magnetic field direction according to a magnetic field direction of an outer magnetic field using magnetic particles, a magnetic field measurement unit for measuring a magnetic field direction with respect to an X-axis magnetic field and Y-axis magnetic field in relation to the outer magnetic field, and a magnetic field detection unit for detecting the X-axis magnetic field, the Y-axis magnetic field and the Z-axis magnetic field based on the stray field and the measured magnetic field direction.