Angle Sensor Magnetic Anisotropy Error Reduction
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Solution Overview
Problem
Existing angle sensor systems experience angular errors due to distortions in the rotating magnetic field and magnetic detection element waveforms, leading to inaccuracies in detected angle values, and require complex configurations with multiple detection and computation circuits.
Innovation Solution
An angle sensor system with a magnetic field generation unit producing a rotating magnetic field containing orthogonal components, using detection signal generation units with magnetic detection elements having specific magnetic anisotropies to reduce errors, allowing the detected angle value to contain reduced errors that vary with half the period, and maintaining a simple configuration by utilizing only one pair of detection signal generation units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple detection circuits and computation circuits are used to reduce angular error, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by utilizing magnetic anisotropy characteristics of the magnetic detection element. Specifically, it exploits the relationship between the magnetic anisotropy energy and the applied magnetic field to modify the detection signal waveform. By carefully selecting and controlling the magnetic anisotropy parameters, the system compensates for waveform distortions and reduces angular error without adding multiple detection circuits or computation circuits, thus maintaining simple device configuration while improving measurement precision.
2Measurement precision
If magnetic anisotropy is introduced in the magnetic detection element, then angular error is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs the self-service principle by utilizing the inherent magnetic anisotropy property of the magnetic detection element itself to compensate for waveform distortions. The magnetic anisotropy, which is an intrinsic characteristic of the material and structure, automatically provides the necessary correction without requiring external adjustment mechanisms or complex calibration procedures. This approach reduces angular error while avoiding the need for extremely tight manufacturing tolerances, as the magnetic anisotropy serves its own compensatory function.
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 system effectively reduces angular errors associated with the rotating magnetic field without increasing complexity, achieving accurate angle detection with a simplified configuration.
Implementation Method 1
The magnetic detection element includes a magnetic layer whose magnetization direction varies according to the direction of the rotating magnetic field. The magnetic layer is provided with magnetic anisotropy.
Implementation Method 2
The magnetic detection element includes a spin-valve magnetoresistance element including a magnetization pinned layer whose magnetization direction is pinned, a free layer whose magnetization direction varies according to the direction of the rotating magnetic field, and a nonmagnetic layer located between the magnetization pinned layer and the free layer.
Data Source
AI summary
An angle sensor system includes a magnetic field generation unit for generating a rotating magnetic field, and an angle sensor for detecting the rotating magnetic field to generate a detected angle value. The rotating magnetic field contains first and second magnetic field components orthogonal to each other. Each of the first and second magnetic field components contains an ideal magnetic field component and an error magnetic field component. The error magnetic field component causes an angular error that varies with ½ the predetermined period. The angle sensor includes first and second detection signal generation units. Each of the first and second detection signal generation units includes a magnetic layer whose magnetization direction varies according to the direction of the rotating magnetic field. The magnetic layer is provided with a magnetic anisotropy that is set to reduce the angular error resulting from the error magnetic field component.