Sensor Device for Rotation Angle Measurement with Magnetic Stray Field Suppression
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Solution Overview
Problem
Existing sensor devices for determining rotation angles of shafts are ineffective in suppressing magnetic stray fields and accurately measuring rotation angles, especially in environments with strong magnetic interference like electric or hybrid vehicles.
Innovation Solution
A sensor device with a semiconductor body and a magnet having a quadrupole magnetic pole arrangement, featuring two-dimensional magnetic field sensors that process sinusoidal or cosinusoidal signals to determine rotation angles, and optionally includes a third sensor for z-direction detection, allowing for suppression of magnetic DC field components and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional magnetic field sensor is used, then the device can detect magnetic fields, but it cannot suppress magnetic stray fields and accurately measure rotation angles in environments with strong magnetic interference
Solution Approach 1:
The sensor device divides the magnetic field detection function into multiple independent sensor elements (first and second magnetic field sensors in x and y directions) within pixel cells. This segmentation allows the system to process magnetic field information differently, enabling suppression of stray field components through differential evaluation of sensor signals while maintaining accurate rotation angle detection.
Solution Approach 2:
The patent introduces an intermediary evaluation method that processes signals from multiple magnetic field sensors through differential evaluation. This intermediary processing layer filters out magnetic stray field interference by comparing signals from sensors positioned at different locations and orientations, thereby isolating the true rotation angle information from harmful magnetic interference.
2Measurement precision
If a simple magnetic field sensor arrangement is used, then the device complexity is low, but the measurement precision is insufficient for suppressing magnetic DC field components
Solution Approach 1:
The pixel cell design integrates multiple magnetic field sensors (first sensor for x-direction, second sensor for y-direction, and optionally third sensor for z-direction) within a single functional unit. This multi-functional arrangement allows a single pixel cell to detect and process magnetic field information from multiple directions, enabling comprehensive suppression of DC field components while maintaining manageable device complexity through integrated design.
Solution Approach 2:
The patent extends the magnetic field detection from a single direction to multiple dimensions by incorporating sensors that detect magnetic fields in x, y, and z directions. This dimensional expansion allows the system to resolve magnetic field vectors completely, enabling effective suppression of stray field components through multi-directional signal processing while organizing the complexity in a structured three-dimensional architecture.
3Measurement precision
If two-dimensional magnetic field sensors are used, then the device can determine rotation angles more accurately, but the manufacturing precision requirements increase
Solution Approach 1:
The patent merges multiple magnetic field sensors into integrated pixel cells that are spaced apart along connecting lines. This merging approach allows the system to achieve high measurement precision through the combined signal processing of multiple sensors while distributing the manufacturing complexity across standardized pixel cell units, reducing the overall precision requirements compared to requiring each individual sensor to be perfectly positioned.
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 device effectively determines rotation angles of shafts with enhanced accuracy and suppresses magnetic stray fields, facilitating easier engine startup and precise position detection in automotive systems, while reducing interference from Earth's magnetic field and power cables.
Implementation Method 1
the first magnetic field sensor detects a magnetic field in the x-direction and the second magnetic field sensor a magnetic field in the y-direction
Implementation Method 2
each pixel cell has a first magnetic field sensor and a second magnetic field sensor
Implementation Method 3
the magnet has a magnetization with four magnetic poles in the direction of the x-y plane
Implementation Method 4
A permanent magnet whose magnetic flux penetrates the sensor is arranged adjacent to the package
Implementation Method 5
the effects of a stray field, for example, due to the Earth's magnetic field or power cables in electric/hybrid vehicles, which have high currents, for example, above 10 amperes, can be suppressed in a simple and reliable manner by the double design of the magnetic field sensors
Data Source
AI summary
A sensor device for suppressing a magnetic stray field, having a semiconductor body with a surface, formed in an x-y plane, and a back surface. Each circle half of a disk-shaped magnet has two magnetic poles and the magnet is rotatable relative to the IC housing around a z-direction. An imaginary lengthening of the axis penetrates the magnet in the center of gravity of the main extension surface of the magnet. A first pixel cell and a second pixel cell are integrated into the surface of the semiconductor body together with a circuit arrangement, and each pixel cell has a first magnetic field sensor and a second magnetic field sensor. The first pixel cell is spaced apart from the second pixel cell along a connecting line, and the first pixel cell in a projection along an imaginary lengthening of the axis is arranged within the two inner circle segments.