Magnetic Sensor Device With Soft Magnetic Structure Hysteresis Control
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Solution Overview
Problem
Magnetic sensors with soft magnetic structures suffer from reduced detection accuracy due to magnetic hysteresis characteristics, where residual magnetization from external fields affects readings at zero magnetic field, leading to hysteresis in detection values.
Innovation Solution
A magnetic sensor device configuration where the soft magnetic structure, with a stripe domain structure, operates within a predetermined variable range of external magnetic fields, ensuring coordinates move along a minor loop within the major loop's region, preventing hysteresis and maintaining detection accuracy. The device includes multiple magnetic sensors and a soft magnetic structure, with the soft magnetic structure being arranged to overlap only certain sensors and featuring a magnetic field converter to output intersecting magnetic field components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a soft magnetic structure is disposed close to a magnetic sensor, then the magnetic sensor can detect magnetic field components more effectively, but the magnetic hysteresis characteristic of the soft magnetic structure causes the detection value to exhibit hysteresis, degrading detection accuracy
Solution Approach 1:
The patent applies preliminary action by subjecting the soft magnetic structure to a magnetization treatment process before actual measurement. This preliminary magnetization aligns the magnetic domains in a specific direction, creating a controlled initial state that prevents random magnetization fluctuations during subsequent measurements, thereby eliminating hysteresis effects in the detection values
Solution Approach 2:
The patent changes the magnetic parameter state of the soft magnetic structure by applying a predetermined magnetization treatment. This transforms the soft magnetic structure from an unmagnetized or randomly magnetized state to a state with controlled magnetization direction and magnitude, fundamentally altering its magnetic characteristics to eliminate hysteresis during operation
2Adaptability or versatility
If the soft magnetic structure is magnetized by an external magnetic field, then it can convert vertical magnetic field components into horizontal components, but residual magnetization remains after the external field becomes zero, causing the detection value to differ from the ideal value
Solution Approach 1:
The patent applies preliminary magnetization treatment to establish a controlled baseline magnetization state in the soft magnetic structure before measurements begin. This preliminary action ensures that when external magnetic fields are applied and removed, the structure returns to a predictable reference state, eliminating random residual magnetization effects
Solution Approach 2:
The patent implements a feedback mechanism where the detection system monitors the magnetic sensor output and compares it against expected values. When residual magnetization causes deviations from ideal detection values, the system detects these errors and applies compensatory corrections, ensuring accurate measurements even when complete demagnetization is difficult to achieve
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 effectively prevents the degradation of detection accuracy caused by magnetic hysteresis, ensuring precise magnetic field detection by maintaining the coordinates within a minor loop, thereby minimizing hysteresis parameters and maintaining sensitivity across varying external magnetic field strengths.
Implementation Method 1
If the soft magnetic structure has a magnetic hysteresis characteristic, the magnetic hysteresis characteristic causes the detection value of the first magnetic sensor to exhibit a hysteresis characteristic
Implementation Method 2
once the soft magnetic structure has been magnetized by an external magnetic field, a certain amount of magnetization remains in the soft magnetic structure even after the external magnetic field becomes zero
Implementation Method 3
Some known magnetic sensors use a plurality of magnetic detection elements provided on a substrate. Examples of the magnetic detection elements include magnetoresistive elements
Data Source
AI summary
A magnetic sensor device includes a magnetic sensor detecting a detection-target magnetic field, and a soft magnetic structure near the sensor. In an orthogonal coordinate system having two orthogonal axes for representing an applied field strength and a magnetization-corresponding value, coordinates representing the applied field strength and the magnetization-corresponding value move along a minor loop not in contact with a major loop as the strength of an external magnetic field including the detection-target magnetic field varies within a variable range, where the applied field strength is a strength of a magnetic field applied to the soft magnetic structure, the magnetization-corresponding value is a value corresponding to magnetization of the soft magnetic structure, and the major loop is, among loops traced by a path of the coordinates as the applied field strength is varied, a loop that is the largest in terms of area of the region enclosed by the loop.