Magnetic Field Sensor Triangular Arrangement for DC Interference
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Solution Overview
Problem
Existing magnetic field measuring devices lack a compact and cost-effective design that allows for accurate measurement of magnetic fields and determination of the angle of rotation, particularly in applications like motor vehicle engines, where precise detection of crankshaft or camshaft positions is required.
Innovation Solution
A magnetic field measuring device featuring a semiconductor body with three monolithically integrated magnetic field sensors and a rotatable magnet with multiple poles, where the sensors are spaced to suppress interfering DC fields and determine the angle of rotation using differential measurements, allowing for a compact and cost-effective configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple magnetic field sensors are integrated on a single semiconductor body in a compact arrangement, then device complexity is reduced and cost is lowered, but measurement precision may be affected by interfering DC magnetic fields
Solution Approach 1:
The magnetic field sensing function is segmented into three separate magnetic field sensors (first, second, and third sensors) arranged in a specific triangular pattern on the semiconductor body. This segmentation allows differential measurement techniques to suppress DC field interference while maintaining compact integration
Solution Approach 2:
Multiple magnetic field sensors are monolithically integrated on a single semiconductor body, merging the sensing functions into one compact device. The sensors are spaced within the projected area of the magnet to achieve both compactness and interference suppression through differential measurements
2Volume of moving object
If magnetic field sensors are spaced close to the magnet axis for compact design, then device size is reduced, but the ability to suppress interfering DC fields through differential measurements is compromised
Solution Approach 1:
The magnetic field sensors are positioned with specific local quality requirements: they are spaced apart from one another and from the magnet axis within the projected area, creating optimal local geometries for differential measurements that suppress DC fields while maintaining compact overall device size
Solution Approach 2:
The sensors are arranged in a two-dimensional triangular pattern within the projected area of the magnet, utilizing spatial distribution in multiple dimensions to achieve both compactness and effective DC field suppression through differential measurement geometry
3Ease of manufacture
If three magnetic field sensors are monolithically integrated on a semiconductor body, then manufacturing cost is reduced and device complexity is lowered, but reliable detection of angle of rotation and magnetic field strength becomes more challenging
Solution Approach 1:
The three monolithically integrated magnetic field sensors serve multiple functions: they detect magnetic field strength, determine angle of rotation through differential measurements, and suppress interfering DC fields. This multi-functionality is achieved through the specific geometric arrangement of the sensors within the magnet's projected area
Solution Approach 2:
The differential measurement arrangement of the three sensors provides inherent feedback for suppressing DC field interference. By comparing measurements from sensors at different positions, the system automatically compensates for DC offsets and determines accurate magnetic field strength and rotation angle
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
Enables reliable and efficient detection of the angle of rotation and magnetic field strength, facilitating the determination of shaft positions in stationary and rotating engines, thereby simplifying engine starting processes.
Implementation Method 1
magnetic field sensors, preferably monolithically integrated
Data Source
AI summary
A magnetic field measuring device having a semiconductor body with a surface parallel to an x-y plane and having a magnet with a flat main extension surface parallel to the x-y plane, the direction of magnetization changes along the main extension surface due to at least two adjacent magnetic poles, the magnet being rotatable relative to the IC package about an axis of rotation extending in a z direction and the z direction being orthogonal to the x-y plane. An imaginary extension of the axis of rotation passes through the magnet. The semiconductor body has three magnetic field sensors spaced apart from one another on the surface, and each of the magnetic field sensors measures the same component of the magnetic field. All magnetic field sensors are located along the imaginary extension of the axis of rotation within the projection of the main extension surface.