XMR Sensor Segmented Strip Stabilizes Magnetization
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Solution Overview
Problem
Conventional magnetoresistive rotational speed sensors experience discontinuities in output signals due to counterrotating magnetic fields and shape anisotropy, leading to jitter and reduced sensitivity, which existing solutions attempt to address with back bias magnets but at the cost of sensitivity.
Innovation Solution
The use of magnetoresistive strips comprising serially connected segments with varying tilt angles, widths, and configurations to average out discontinuities, thereby stabilizing magnetization and reducing signal jitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a back bias magnet is mounted on the rear side of an xMR sensor to create a bias magnetic field, then the direction of free layer magnetization is stabilized and free layer rotation is prevented, but sensor sensitivity is reduced and the solution requires significant effort
Solution Approach 1:
The xMR strip is divided into multiple segments with different tilt angles relative to the strip axis. Each segment experiences the magnetic field differently, and the combined output averages out the discontinuities while maintaining sensitivity. This segmentation allows the sensor to achieve stability without requiring a back bias magnet that would reduce sensitivity.
2Measurement precision
If the xMR strip width is reduced to less than 2 micrometers to provide defined sensitivity by shape anisotropy, then sensitivity is improved, but discontinuities in the output signal occur due to domain wall formation and edge effects
Solution Approach 1:
The strip is segmented into multiple sections with different tilt angles. By using multiple segments rather than a single narrow strip, the patent maintains the sensitivity benefits of narrow strips while averaging out the discontinuities that occur in individual segments, thus improving signal continuity.
Solution Approach 2:
Different segments of the xMR strip have different tilt angles, creating local variations in how each segment responds to the magnetic field. This local differentiation causes discontinuities to occur at different phases in different segments, and when combined, these discontinuities average out to produce a more continuous overall signal.
3Power
If the xMR strip length is increased to about 300 micrometers to provide sufficient signal output, then signal strength is improved, but the magnetic signal field becomes non-homogeneous over the entire strip length due to limited pole wheel thickness
Solution Approach 1:
The long xMR strip is divided into multiple segments along its length, each experiencing slightly different magnetic field conditions. The segmented configuration allows the sensor to maintain a long effective length for sufficient signal strength while the different segments average out the non-homogeneity effects caused by the limited pole wheel thickness.
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
This configuration significantly reduces or eliminates signal discontinuities, enhancing sensor performance and maintaining sensitivity by averaging phase-shifted discontinuities and stabilizing magnetization across the strip.
Implementation Method 1
Magnetoresistive sensors can include giant magnetoresistive (GMR), tunnel magnetoresistive (TMR), anisotropic magnetoresistive (AMR) and other technologies, referred to collectively as xMR technologies
Implementation Method 2
The xMR structures positioned near the wheel in these sensors are typically narrow strips with a homogenous width of, for example, less than 2 micrometers (μm) in order to provide a defined sensitivity by the shape anisotropy and a length of about, for example, 300 μm
Implementation Method 3
The xMR structures positioned near the wheel in these sensors are typically narrow strips with a homogenous width of, for example, less than 2 micrometers (μm) in order to provide a defined sensitivity by the shape anisotropy
Data Source
AI summary
Some embodiments relate to a magnetoresistive sensor element comprising a magnetoresistive strip. The magnetoresistive strip includes a first linear segment, and a second linear segment arranged in series with the first linear segment. The second linear segment adjoins the first linear segment at a first inner corner corresponding to a first obtuse angle having a first magnitude. The magnetoresistive strip also includes a third linear segment arranged in series with the first and second linear segments, and a fourth linear segment arranged in series with the first, second, and third linear segments. The fourth linear segment adjoins the third linear segment at a second inner corner corresponding to a second obtuse angle having a second magnitude. Te second magnitude differs from the first magnitude.