AMR Magnetic Field Sensor with Reference Detector for Accurate Density Measurement
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Solution Overview
Problem
Magnetic field detectors, such as AMR detectors, face challenges in accurately identifying field density due to operation in linear and non-linear regions, leading to potential false identification and reduced measurement accuracy.
Innovation Solution
A magnetic field sensing apparatus comprising an AMR detector, a reference magnetic field detector, and a controller that selects between the AMR detector's output voltage and a saturation voltage based on a predetermined threshold value, determined by the reference detector's output, to accurately determine the field density and prevent misidentification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the AMR detector operates in both linear and non-linear regions, then the detection range is extended, but the measurement accuracy deteriorates due to false identification of field density
Solution Approach 1:
The patent divides the detection process into two segments: one for detecting the direction of the magnetic field using the AMR detector, and another for detecting the magnitude (field density) using a Hall detector. This segmentation allows each detector to operate in its optimal region, resolving the contradiction between extended detection range and measurement accuracy.
Solution Approach 2:
The patent introduces a controller as an intermediary that receives signals from both the AMR detector and Hall detector, processes the information, and determines the final magnetic field characteristics. This intermediary coordinates the outputs of both detectors to achieve accurate measurement across the full detection range.
2Device complexity
If the AMR detector is used alone, then the device complexity is reduced, but the reliability of magnetic field detection deteriorates due to ambiguous output voltage correspondence
Solution Approach 1:
The patent merges the functionality of two different detectors (AMR detector for direction and Hall detector for magnitude) into a single magnetic field sensing system. This combination provides unambiguous detection results by capturing both directional and magnitude information, thereby improving reliability without excessive complexity.
Solution Approach 2:
The patent creates a multi-functional detection system where the AMR detector provides directional information and the Hall detector provides magnitude information. Together, they form a universal magnetic field sensing apparatus that can accurately characterize both the direction and strength of magnetic fields in various operating conditions.
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 solution enhances the accuracy of magnetic field detection by correctly identifying whether the AMR detector operates in a linear or non-linear region, thereby preventing false identification of field density and improving measurement precision.
Implementation Method 1
an anisotropic magneto-resistive (AMR) detector generates a first output voltage signal in response to a detected magnetic field
Implementation Method 2
a reference magnetic field detector generates a second output voltage signal in response to the detected magnetic field
Data Source
AI summary
A magnetic field sensing apparatus and detection method thereof are provided. The magnetic field sensing apparatus includes an anisotropic magneto-resistive (AMR) magnetic field detector, a reference magnetic field detector, and a controller. The AMR magnetic field detector generates a first output voltage according to a detected magnetic field. The reference magnetic field detector generates a second output voltage according to the detected magnetic field. The controller identifies whether an absolute value of a field density of the detected magnetic field is larger or smaller than a predetermined value or not, and selects the first output voltage or a saturation voltage to be a magnetic field detection result accordingly.