Magnetic Field Sensor Temperature Compensated Threshold Power Up
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Solution Overview
Problem
Conventional magnetic field sensors, such as gear tooth sensors, often provide inaccurate output signals immediately after power-up or when the target object is stationary or rotating at low speed, due to temperature and air gap variations affecting the magnetic field signal, leading to unreliable detection of gear teeth or ring magnet pole edges.
Innovation Solution
A magnetic field sensor with a temperature-compensated threshold system, including a memory to store threshold values at different temperatures and a threshold module to generate an interpolated threshold based on these values, which is compared with the magnetic field signal to improve accuracy and stability of the output signal, especially during initial power-up and low-speed rotations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional magnetic field sensor uses a fixed threshold for signal comparison, then the device complexity is low, but the measurement precision deteriorates due to temperature and air gap variations
Solution Approach 1:
The patent applies preliminary action by pre-storing multiple threshold values corresponding to different temperatures in memory before actual measurement. During operation, the system retrieves and interpolates the appropriate threshold based on current temperature, eliminating the need for real-time threshold calculation and ensuring accurate comparison without complex processing.
Solution Approach 2:
The patent implements parameter changes by making the threshold value dynamic based on temperature conditions. Instead of using a fixed threshold, the system stores multiple threshold values at different temperatures and interpolates the appropriate threshold based on current temperature, allowing the threshold parameter to adapt to environmental changes and maintain measurement precision.
2Productivity
If the magnetic field sensor operates immediately after power-up, then the productivity is high with no warm-up delay, but the measurement precision deteriorates due to unstable internal conditions
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation values in memory during manufacturing or initialization. These pre-computed values enable the sensor to immediately compensate for temperature and air gap variations upon power-up without requiring a warm-up period for real-time calculation, thus maintaining both high productivity and measurement precision.
Solution Approach 2:
The patent implements beforehand cushioning by pre-storing multiple threshold values at different temperatures and conditions in memory. This preparation cushions against the instability that would normally occur at power-up by having ready-to-use compensation data, allowing the sensor to provide accurate measurements immediately without requiring stabilization time.
3Measurement precision
If the magnetic field sensor uses temperature-compensated interpolated threshold, then the measurement precision is improved across varying conditions, but the device complexity increases due to additional memory and processing
Solution Approach 1:
The patent reduces device complexity by applying preliminary action - all complex threshold calculations and temperature compensation data are pre-computed and stored in memory during manufacturing. The runtime operation simply involves reading stored values and performing simple interpolation, eliminating the need for complex real-time calculation hardware while maintaining high measurement precision.
Solution Approach 2:
The patent replaces complex mechanical or analog threshold adjustment mechanisms with a digital memory-based system. Instead of using complex analog circuits or mechanical adjustments to compensate for temperature variations, the system uses digital storage and simple interpolation algorithms, reducing overall device complexity while improving 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 ensures accurate and reliable detection of the absolute angle of rotation and direction of a target object by maintaining a stable threshold signal despite temperature and air gap changes, providing precise output signals even at initial power-up and low-speed rotations, enhancing engine operation and other applications.
Implementation Method 1
Magnetic field sensors generally include a magnetic field sensing element and other electronic components
Implementation Method 2
Various types of magnetic field sensing elements are known, including Hall Effect elements and magnetoresistance elements
Data Source
AI summary
A magnetic field sensor includes one or more magnetic field sensing elements configured to generate a magnetic field signal responsive to a magnetic field and a detector coupled to receive an interpolated threshold and a signal representative of the magnetic field signal, wherein the detector is configured to compare the interpolated threshold with the signal representative of the magnetic field signal to generate a detector output signal. A memory is configured to store a first threshold value indicative of a threshold value at a first temperature and a second threshold value indicative of a threshold value at a second temperature lower than the first temperature and a threshold module coupled to the memory and configured to generate the interpolated threshold based on the stored first and second threshold values.