Magnetoresistive Sensor Bridge Circuit for Magnet Misalignment Compensation
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Solution Overview
Problem
Position sensors are highly sensitive to stray fields and misalignment, leading to inaccurate measurements due to movement in directions perpendicular to the intended detection axis.
Innovation Solution
A magnetoresistive field sensor with pairs of magnetoresistive elements arranged in a bridge circuit, where each pair's sensitivity direction is aligned within a plane perpendicular to the measurement direction, compensating for movement in other directions by maintaining a consistent output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple magnet and field sensor are used for position sensing, then the sensor is simple to manufacture and inexpensive, but it is highly sensitive to stray fields and misalignment of the magnet
Solution Approach 1:
The sensor divides the detection function into multiple magnetoresistive elements arranged in pairs, where each pair detects magnetic field components in different directions. This segmentation allows the sensor to distinguish between intended motion and unwanted lateral movements or stray fields, improving reliability while maintaining manufacturing simplicity through modular element arrangement
Solution Approach 2:
Each magnetoresistive element is configured with specific sensitivity directions oriented in different directions (preferably substantially perpendicular). This local differentiation of sensitivity characteristics enables the sensor to selectively respond to magnetic field changes in specific directions, compensating for misalignment and stray field interference while maintaining overall system simplicity
2Device complexity
If a single field sensor is used to detect magnet movement, then the sensor structure is simple, but movement of the magnet in directions perpendicular to the detection axis affects the position measurement
Solution Approach 1:
The invention transitions from single-detection to multi-directional detection by arranging magnetoresistive elements in pairs with sensitivity directions oriented in different directions. This dimensional expansion allows the sensor to detect and compensate for lateral movements in addition to the primary detection axis, improving measurement precision without significantly increasing structural complexity
Solution Approach 2:
Multiple magnetoresistive elements are merged into a unified bridge circuit configuration where elements of the same pair are connected in series between two nodes. This merging allows the sensor to process information from multiple detection directions simultaneously through a single integrated circuit structure, maintaining device simplicity while achieving enhanced measurement precision
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 effectively isolates movement in the direction of detection from lateral movements, providing accurate position measurements while minimizing the impact of external magnetic fields and misalignment.
Implementation Method 1
a plurality of magnetoresistive elements arranged in pairs. The elements of the same pair are arranged so that their sensitivity direction is oriented in the same direction
Implementation Method 2
The magnetoresistive sensors and their sensitivity directions are generally arranged in a plane, which is perpendicular to the direction of measurement of the device. The elements of each pair are arranged in series between two nodes so as to form a bridge circuit. As such, movement of the magnet in the first plane causes a substantially equal change in the elements of each pair, thereby compensating for this movement in the output signal.
Data Source
AI summary
The disclosure provides a magneto resistive field sensor for detecting position in a particular direction. The sensor includes a plurality of magneto resistive elements arranged in pairs. The elements of the same pair are arranged so that their sensitivity direction is oriented in the same direction. The elements of different pairs are oriented so that their sensitivity direction is oriented in a different direction, preferably substantially perpendicular to another pair. The magneto resistive sensors and their sensitivity directions are generally arranged in a plane, which is perpendicular to the direction of measurement of the device. The elements of each pair are arranged in series between two nodes so as to form a bridge circuit. As such, movement of the magnet in the first plane causes a substantially equal change in the elements of each pair, thereby compensating for this movement in the output signal.