Magnetic Field Concentrator for xMR Sensor Sensitivity
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Solution Overview
Problem
Magnetic field sensors struggle with sensitivity at varying distances from magnetically polarized rings due to the limited range of magnetic fields, which affects the accuracy of detecting the speed and direction of rotating wheels, especially with assembly tolerances leading to inconsistent positioning.
Innovation Solution
An integrated sensor and magnetic field concentrator device with xMR sensor elements and a magnetic field concentrator, where the magnetic field concentrator guides magnetic flux perpendicularly to the sensor elements, enhancing sensitivity by amplifying flux density and suppressing unwanted y-components of the magnetic field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the distance between the field sensor and the pole-ring is increased to accommodate assembly tolerances, then the device becomes more robust to positioning variations, but the magnetic field strength decreases exponentially causing loss of sensitivity
Solution Approach 1:
A magnetic field concentrator is introduced as an intermediary component between the pole-ring and the field sensor. This concentrator captures and guides magnetic flux from the pole-ring to the sensor elements, enabling effective sensing at larger distances while maintaining sensitivity. The concentrator acts as a mediator that bridges the gap between the magnet source and sensor, resolving the contradiction between distance tolerance and field strength.
Solution Approach 2:
The magnetic field concentrator changes the spatial distribution parameters of the magnetic flux, concentrating and guiding it along specific paths to the sensor elements. This parameter transformation allows the system to maintain high flux density at the sensor location even when positioned at varying distances from the pole-ring, thus preserving measurement precision across different positions.
2Measurement precision
If many poles are placed on the ring to achieve fine resolution, then the rotational speed detection accuracy improves, but the magnetic field of each pole becomes more confined and decreases more rapidly with distance
Solution Approach 1:
The magnetic field concentrator serves as an intermediary that extends the effective range of each pole's magnetic field. By guiding and concentrating the flux from each closely-spaced pole, the concentrator enables the sensor to detect fields from multiple poles over a larger distance, thereby maintaining fine resolution capability while overcoming the limited field extension range.
Solution Approach 2:
The concentrator structure extends the magnetic field interaction in the vertical dimension (perpendicular to the ring plane), allowing the sensor to effectively 'reach' closer poles that would otherwise be too close together for direct sensing. This dimensional approach enables fine resolution detection without sacrificing field range.
3Measurement precision
If the gap between sensor elements is reduced to improve sensitivity, then the magnetic field detection capability increases, but the device becomes more sensitive to assembly tolerances and positioning variations
Solution Approach 1:
The magnetic field concentrator acts as a buffer and guide that decouples the sensor elements from direct dependence on precise positioning relative to the pole-ring. By concentrating and directing flux through a larger effective area, the concentrator allows the use of larger gaps between sensor elements while maintaining sensitivity, thereby improving robustness to assembly variations.
Solution Approach 2:
The concentrator merges and combines magnetic flux from multiple pole regions into a unified flux path that reaches the sensor elements. This merging effect allows the sensor to integrate signals from a broader spatial region, reducing sensitivity to small positioning variations and assembly tolerances while maintaining detection capability.
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 significantly increases magnetic sensitivity, allowing accurate detection of rotational speed and direction across a range of distances, improving resolution and reducing positional inaccuracies caused by assembly tolerances.
Implementation Method 1
a magnetic field concentrator disposed in the first gap and configured to guide magnetic flux from an external source in a direction perpendicular to the at least two xMR sensor elements
Implementation Method 2
at least two xMR sensor elements spaced apart from each other on a surface of a die
Data Source
AI summary
Embodiments relate to integrated sensor and magnetic concentrator devices and methods. In one embodiment, an integrated sensor and magnetic field concentrator device comprises a sensor device comprising at least two xMR sensor elements spaced apart from each other on a surface of a die to define a first gap of about 5 millimeters (mm) or less; and a magnetic field concentrator disposed in the first gap and configured to guide magnetic flux from an external source in a direction perpendicular to the at least two xMR sensor elements.