Magneto-resistive Sensor Angular Alignment for Gain and Accuracy
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Solution Overview
Problem
Conventional magnetic sensors face errors in measuring external magnetic fields due to small hysteresis of the magnetization free layer, which limits gain, and increasing hysteresis of the magnetization fixed layer leads to frequent errors.
Innovation Solution
A magnetic field measurement method using a magneto-resistive effect element with a stacked body of a magnetization-free layer, a nonmagnetic layer, and a magnetization fixed layer, where the magnetization direction of the fixed layer is set at an angle of 45 degrees or less to the longitudinal direction, and a magnetic field is applied to saturate the magnetization-free layer in one direction, allowing measurement of the external field in the reverse direction to utilize high linearity regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the hysteresis of the magnetization fixed layer is made large to produce a large gain, then the gain when measuring the external magnetic field increases, but errors when measuring the external magnetic field occur frequently
Solution Approach 1:
The patent changes the magnetization direction parameter of the magnetization fixed layer from perpendicular to the longitudinal direction to an angle of 45 degrees or less relative to the longitudinal direction. This parameter change increases the hysteresis of the magnetization free layer, thereby achieving large gain while maintaining measurement accuracy through the controlled angular relationship between magnetic fields and layer orientations
2Reliability
If the hysteresis of the magnetization free layer is made small to reduce measurement errors, then measurement accuracy improves, but the gain when measuring the external magnetic field becomes small
Solution Approach 1:
The patent modifies the angular parameter between the magnetization direction of the fixed layer and the longitudinal direction to 45 degrees or less, which fundamentally changes the hysteresis characteristics of the magnetization free layer. This parameter adjustment simultaneously achieves both large gain and maintained measurement accuracy by optimizing the magnetic field interaction geometry
3Measurement precision
If a magnetic field is applied to saturate the magnetization-free layer in one direction, then the magnetized state is fixed and measurement linearity improves, but additional magnetic field application steps are required
Solution Approach 1:
The patent applies a magnetic field in advance to saturate the magnetization-free layer in one direction before the actual measurement. This preliminary action fixes the magnetized state and ensures high linearity during subsequent measurements, with the benefit that the same magnetic field application means can be used without adding complex additional components
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 enables a large gain in measuring external magnetic fields while reducing errors by fixing the magnetized state of the magnetization-free layer and utilizing regions of high linearity in the resistance value relationship, simplifying the magnetic field application structure.
Implementation Method 1
Magnetic sensors which employ a magneto-resistive effect element such as a GMR (Giant Magneto-Resistive) element are known. These magnetic sensors utilize a phenomenon whereby the resistance value of the magneto-resistive effect element depends on the relative angle between the magnetization orientations of a magnetization-free layer and a magnetization fixed layer
Implementation Method 2
magnetic field application means for generating a magnetic field by being supplied with a current
Implementation Method 3
an external magnetic field which is to be measured is applied to the magnetization-free layer in order to change the magnetization direction thereof
Data Source
AI summary
The magnetic field measurement method has: a step of preparing a magnetic sensor which includes: a magneto-resistive effect element having a magnetization-free layer and a magnetization fixed layer, and having a longitudinal direction; and magnetic field application means, wherein the magnetization direction of the magnetization fixed layer is fixed in a direction which forms an angle equal to or less than 45 degrees to the longitudinal direction, and a magnetic field generated by the magnetic field application means forms an angle equal to or less than 45 degrees to the longitudinal direction; a step of saturating the magnetization of the magnetization-free layer by the magnetic field application means and magnetizing the magnetization-free layer in one direction in the longitudinal direction; and a step of measuring the strength of an external magnetic field by applying the external magnetic field to the magnetization-free layer in the other direction in the longitudinal direction.