Magnetoresistive Current Sensor with Magnetic Sheet Bias
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Solution Overview
Problem
Current current sensors face challenges in miniaturization, linearity of detection sensitivity, and high-frequency response, particularly when measuring control currents, and are influenced by external turbulence magnetic fields.
Innovation Solution
A magnetic sensor configuration with a magnetoresistive element and a magnetic sheet applied to provide a bias magnetic field, reducing external turbulence and enhancing linearity and stability, while allowing for a more compact design by using the magnetic sheet to apply a bias field directly or indirectly to the magnetoresistive element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If permanent magnets or coils are arranged on both sides of the magnetoresistive element to apply bias magnetic field, then the bias magnetic field can be applied, but the device size increases and space utilization decreases
Solution Approach 1:
The magnetic sheet is integrated directly onto the element substrate, merging the bias field generation function into the substrate structure itself. This eliminates the need for separate permanent magnets or coils on both sides, reducing device volume while maintaining reliable bias magnetic field application to the magnetoresistive element
Solution Approach 2:
The element substrate serves multiple functions: it provides mechanical support for the magnetoresistive element and simultaneously serves as the mounting base for the magnetic sheet that generates the bias magnetic field. This multi-functionality reduces the need for additional components, achieving miniaturization without compromising bias field reliability
2Volume of moving object
If traditional current measurement methods using resistances are used, then the measurement can be conducted, but the control system is influenced adversely and miniaturization is difficult
Solution Approach 1:
The patent replaces traditional resistance-based electrical measurement methods with a magnetic field detection approach using magnetoresistive elements. This substitution enables indirect current measurement through magnetic field gradient detection, achieving miniaturization while maintaining measurement precision and avoiding adverse influences on the control system
Solution Approach 2:
The magnetoresistive element acts as an intermediary between the current to be measured and the measurement system. By detecting the magnetic field gradient generated by the current through the magnetic sheet, the system can measure current indirectly without direct electrical contact, enabling miniaturization while preserving measurement accuracy
3Measurement precision
If Hall device is used to detect current magnetic field, then the measurement can be performed, but the linearity of detection sensitivity and high-frequency response are inadequate
Solution Approach 1:
The patent changes the detection mechanism from Hall effect to magnetoresistive effect, utilizing the resistance change characteristics of the magnetoresistive element in response to magnetic field variations. This parameter change improves linearity of detection sensitivity and high-frequency response while the integrated magnetic sheet configuration simplifies the overall device structure
Solution Approach 2:
The patent employs a composite structure combining the element substrate, magnetoresistive element, and magnetic sheet into an integrated unit. This composite configuration achieves improved detection characteristics through the synergistic interaction of components while maintaining structural simplicity and ease of fabrication
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 achieves precise and stable resistance changes in response to current magnetic fields, enabling high-precision current measurement with improved linearity and reduced external interference, while allowing for a more compact and efficient use of space compared to traditional methods using permanent magnets or coils.
Implementation Method 1
a giant magnetoresistive element developing a Giant Magneto-Resistive effect (hereinafter referred to as GMR element) is arranged in a current magnetic field generated by the control current
Implementation Method 2
a magnetic sheet attached on one side of the element substrate so as to apply a bias magnetic field to the magnetoresistive element
Data Source
AI summary
The present invention provides a current sensor of smaller and simpler configuration, capable of measuring a current to be detected with high precision and stability. A magnetic sensor includes: an element substrate including a magnetoresistive element, the magnetoresistive element having a pinned layer with a magnetization pinned to a direction, an intermediate layer, and a free layer whose magnetization direction changes according to an external magnetic field; and a magnetic sheet attached on one side of the element substrate so as to apply a bias magnetic field to the magnetoresistive element.