MI Sensor Stabilizing Impedance via Bias Field
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Solution Overview
Problem
Conventional magnetic field detection sensors with MI elements face challenges in maintaining a predetermined impedance characteristic near the zero magnetic field peak, leading to reduced detection range and sensitivity due to disorder in impedance characteristics.
Innovation Solution
A magnetic field detection sensor is designed with a magneto-impedance element on a non-magnetic board, featuring a magnetic film with magnetic anisotropy aligned with the detection direction and a magnetic field generating portion to stabilize the impedance characteristic, ensuring a predetermined inclination near the zero magnetic field peak.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If an MI element is designed to have monotonously decreasing impedance characteristic with zero magnetic field as peak, then the detection range can be enlarged, but the impedance characteristic becomes disordered in the vicinity of zero magnetic field peak
Solution Approach 1:
The patent applies parameter changes by introducing a bias magnetic field in the thickness direction of the magnetic film through a magnetic field generating portion. This changes the operating point of the MI element from the peak region (where impedance characteristic is disordered) to a region with predetermined inclination, thereby stabilizing the impedance characteristic while maintaining large detection range
Solution Approach 2:
The patent uses a magnetic field generating portion (such as a permanent magnet or coil) as an intermediary to apply a bias magnetic field to the MI element. This intermediary component mediates between the structural design of the MI element and the desired impedance characteristic, enabling stable operation without requiring redesign of the MI element itself
2Reliability
If the MI element operates to avoid the vicinity of zero magnetic field, then the impedance characteristic stability is improved, but the detection range decreases and sensitivity is reduced
Solution Approach 1:
The patent changes the parameter of magnetic field operating point by superimposing a bias magnetic field in the thickness direction. This shifts the operating region from the peak vicinity (unstable) to a slope region (stable), allowing the sensor to operate in the stable region while still covering a wide detection range including the zero magnetic field point
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 stabilizes the impedance characteristic near the zero magnetic field peak, enhancing detection sensitivity and range by generating a magnetic field in the thickness direction of the magnetic film, while the bus bar secures the positional relationship between the magneto-impedance element and magnet, preventing disruptions from vibrations.
Implementation Method 1
detects an external magnetic field from an output obtained by applying alternating current to the magneto-impedance element using a magneto-impedance effect
Implementation Method 2
provides a magnetic field generating portion which generates a magnetic field in a thickness direction of the magnetic film
Data Source
AI summary
A magnetic field detection sensor includes a magneto-impedance element and detects an external magnetic field from an output obtained by applying alternating current to the magneto-impedance element using a magneto-impedance effect. The magneto-impedance element includes a non-magnetic board and a magnetic film formed on a surface of the non-magnetic board, a longitudinal direction of the magnetic film is set as a detection direction of the external magnetic field, and magnetic anisotropy is provided such that a magnetization easy axis of the magnetic film is the same as the detection direction of the external magnetic field. The magnetic field detection sensor further includes a magnetic field generating portion which generates a magnetic field in a thickness direction of the magnetic film.