Linear TMR Sensor With Integrated Back-Bias Magnet
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Solution Overview
Problem
Existing magnetic linear position sensors face challenges such as inability to provide absolute position measurements, large package size, high cost, and limited capability for position measurement at power-on, along with reliability issues due to Hall-based sensing elements.
Innovation Solution
A linear TMR sensor system with an integrated back-bias magnet, featuring a sensor module with a back-bias magnet and a sensor chip equipped with TMR sensing elements, which determines characteristics of magnetic field components to generate a sensor signal corresponding to the linear position of a ferromagnetic object.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Hall-based sensing elements are used in magnetic linear position sensors, then the sensors can detect magnetic fields, but the reliability is reduced and accuracy is limited
Solution Approach 1:
The patent transitions from Hall-based sensing to TMR (tunnel magnetoresistive) sensing elements, representing a fundamental change in the physical parameter and mechanism used for magnetic field detection. TMR elements provide higher sensitivity and accuracy compared to Hall sensors, directly resolving the contradiction between reliability and measurement precision by adopting a superior sensing technology with different operational characteristics.
2Measurement precision
If conventional magnetic linear position sensor designs are used, then position detection is possible, but the package size is large
Solution Approach 1:
The patent integrates the back-bias magnet directly onto the sensor chip, merging two previously separate components (magnet and sensor) into a single integrated unit. This integration dramatically reduces the overall package size while maintaining full position detection functionality, resolving the contradiction between detection capability and compactness.
Solution Approach 2:
The patent employs a vertical stacking architecture where the back-bias magnet is positioned beneath the sensor chip in the Z-direction, rather than placing components side-by-side in the planar X-Y dimensions. This dimensional reorganization enables compact integration and reduces the footprint area, effectively solving the package size issue while preserving detection performance.
3Productivity
If conventional sensor designs are used, then incremental position measurement is possible, but absolute position measurement capability is lost
Solution Approach 1:
The integrated back-bias magnet continuously establishes a predetermined magnetic field orientation before measurement begins, creating a reference framework that enables absolute position determination. This preliminary magnetic field configuration allows the sensor to provide absolute position information immediately upon power-up, without requiring movement or calibration, thus resolving the contradiction between measurement capability and information retention.
4Measurement precision
If conventional magnetic linear position sensors are used, then position detection is possible, but the cost is high
Solution Approach 1:
The patent combines the back-bias magnet and sensor chip into a single integrated module, reducing the total component count and assembly steps. This merging of components simplifies the manufacturing process, reduces material requirements, and lowers overall production costs while maintaining high measurement precision through the advanced TMR sensing technology.
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 improved sensor system achieves a reduced package size, lower cost, enhanced reliability due to high accuracy TMR sensing elements, capability for absolute position measurement, and robustness against stray fields, while also allowing for position measurement at power-on.
Implementation Method 1
a sensor chip including a first set of tunnel magnetoresistive (TMR) sensing elements
Data Source
AI summary
A sensor module may include a back-bias magnet with a magnetization in a first direction. The sensor module may include a sensor chip including a first set of tunnel magnetoresistive (TMR) sensing elements. The sensor chip may be configured to determine a characteristic of a first magnetic field component using the first set of TMR sensing elements, and to generate a sensor signal based at least in part on the characteristic of the first magnetic field component. A value of the sensor signal may correspond to a linear position of a ferromagnetic object.