Magnetic Sensor Bias Magnetization for Symmetric Linear Output
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Solution Overview
Problem
Existing magnetic sensors face challenges in stabilizing the magnetization state of elements due to the difficulty in applying a bias magnetic field parallel to the short axis of certain sensor bridge components, leading to asymmetry and reduced linearity in output.
Innovation Solution
A manufacturing method for magnetic sensors involving the application of an external magnetic field at an angle to both magnet layers, allowing simultaneous magnetization of multiple magnet layers to different states, thereby stabilizing the magnetization of magnetization free layers and improving sensor symmetry and linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If magnets are magnetized in the same direction to simplify the magnetization process, then the magnetization process becomes easier and can be completed in a single process, but the magnetization state of elements with different orientations cannot be stabilized
Solution Approach 1:
The patent applies different magnetization directions to different magnet layers based on their local requirements. Specifically, first magnet layers are magnetized in a first direction while second magnet layers are magnetized in a second direction that is different from the first direction. This local differentiation allows each magnet layer to provide the appropriate bias field for its associated sensor bridge elements, stabilizing the magnetization state of all elements regardless of orientation.
2Reliability
If a bias magnetic field is applied parallel to the long axis of one set of elements, then the magnetization state of that set is stabilized, but the magnetization state of elements with perpendicular orientation cannot be stabilized
Solution Approach 1:
The patent introduces asymmetry in the magnetization configuration by using different magnetization directions for different magnet layers. The first magnet layers are magnetized in a first direction while the second magnet layers are magnetized in a second direction. This asymmetric arrangement allows the bias field to be optimized for each set of sensor bridge elements independently, accommodating elements with different orientations (parallel and perpendicular to the bias field direction).
3Reliability
If multiple magnet layers are magnetized in different directions, then the magnetization state of all elements can be stabilized, but the magnetization process becomes more complex
Solution Approach 1:
The patent segments the magnetization process into distinct stages corresponding to different magnet layers. First magnet layers are magnetized in a first direction, and then second magnet layers are magnetized in a second direction. This segmentation allows for controlled, step-by-step magnetization that achieves the complex overall goal of stabilizing all element magnetization states while managing the process complexity through systematic division.
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 method enables efficient magnetization of multiple magnet layers to different states in a single process, enhancing the symmetry and linearity of magnetic sensor output by applying a bias magnetic field effectively in desired directions.
Implementation Method 1
applying an external magnetic field from a direction at an angle that is approximately equal to each the first direction and the second direction while the two first magnet layers, the two second magnet layers, the first soft magnetic layer, and the second soft magnetic layer are supported on a substrate, thereby magnetizing the two first magnet layers and the two second magnet layers
Data Source
AI summary
A magnetic sensor comprises: a first magnetic field sensing element that includes a magnetic field sensing axis parallel to a first direction, two first magnet layers that are arranged in a second direction perpendicular to the first direction, and a first soft magnetic layer that is sandwiched between the two first magnet layers in the second direction; a second magnetic field sensing element that includes a magnetic field sensing axis parallel to the second direction, two second magnet layers that are arranged in the first direction, and a second soft magnetic layer that is sandwiched between the two second magnet layers in the first direction; and a substrate that supports the first and second magnetic field sensing elements. The first and second magnet layers are magnetized by applying an external magnetic field from a direction that is at approximately equal angles to each of the first and second directions.