Unequally Spaced Magnetic Field Sensor for Absolute Position
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional magnetic field sensors struggle to provide accurate output signals when the target object is stationary or rotating slowly, particularly in identifying the absolute or relative angle of rotation, and require time to become fully accurate, which can lead to inaccuracies in engine control systems.
Innovation Solution
A magnetic field sensor with five or more magnetic field sensing elements, unequally spaced, which allows for immediate identification of the target object's position and rotation direction, even when stationary, by generating multiple magnetic field signals and using an electronic circuit to compare these signals to a threshold, enabling accurate edge detection and tooth/valley differentiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional magnetic field sensors use equally spaced sensing elements, then the device complexity is reduced and manufacturing is easier, but the measurement precision deteriorates because accurate position identification cannot be achieved when the target object is stationary or rotating slowly
Solution Approach 1:
The patent applies asymmetry by configuring magnetic field sensing elements with unequal spacing along the sensing path. Specifically, the spacing between adjacent sensing elements varies, with some gaps being larger and others smaller, creating an asymmetric pattern that allows the system to encode absolute position information. This asymmetric arrangement enables the sensor to distinguish between different angular positions even when the target is stationary, resolving the technical contradiction between measurement precision and device complexity.
2Reliability
If the magnetic field sensor requires substantial rotation to provide accurate output signals, then the device complexity is reduced, but the loss of time increases because the sensor cannot provide immediate accurate readings upon power up or when the target is stationary
Solution Approach 1:
The patent implements preliminary action by pre-configuring the sensing elements in an unequal spacing arrangement that encodes absolute position information. This allows the sensor to immediately provide accurate position readings upon power-up without requiring the target to rotate through a substantial angle. The asymmetric spacing pattern is designed beforehand to represent specific angular positions, enabling the sensor to function accurately from the very first measurement, thus eliminating the delay inherent in conventional sensors that require multiple rotation cycles to calibrate.
3Loss of time
If conventional TPOS detectors are used to provide immediate accurate output signals, then the loss of time is reduced, but the measurement precision deteriorates because the detector cannot identify the absolute angle of rotation when the target object is stationary
Solution Approach 1:
The patent applies segmentation by dividing the sensing path into multiple discrete sensing zones, each associated with a specific angular position. The unequal spacing creates distinct segments that correspond to different portions of the rotation cycle. By comparing which sensing elements detect the magnetic field at any given moment, the system can immediately determine the absolute angular position without requiring rotation, thus achieving both rapid response and precise angle identification simultaneously.
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 provides accurate and immediate output signals for both stationary and rotating target objects, enhancing the precision of engine control systems by accurately identifying the position, speed, and direction of rotation, and reducing the time required for sensor calibration.
Implementation Method 1
Each one of the plurality of magnetic field sensing elements generates a magnetic field signal responsive to a magnetic field generated by the magnet and influenced by a position of features on the target object
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A magnetic field sensor for sensing a movement of a target object an include a substrate having a major planar surface and three or more magnetic field sensing elements disposed upon the major planar surface of the substrate. The three or more magnetic field sensing elements can have respective major response axes, each major response axis parallel to the major planar surface of the substrate. The three or more magnetic field sensing elements comprise first and third magnetic field sensing elements and a second magnetic field sensing element disposed between the first and third magnetic field sensing elements. A first spacing between the first and second magnetic field sensing elements is less than a second spacing between the second and third magnetic field sensing elements. No other magnetic field sensing elements are disposed between the first and third magnetoresistance elements.