Magnetic Sensor Angular Error Cancellation via Phase-Differing Detection Units
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic sensors using magnetoresistive elements face errors in detecting the angle of an external magnetic field due to distortion in output signal waveforms, caused by both the elements and the external magnetic field, leading to inaccuracies in rotational or linear position detection.
Innovation Solution
The magnetic sensor employs two detection units with distinct configurations of magnetoresistive elements and arithmetic circuits to calculate the angle of the external magnetic field with respect to a reference direction, where the output signals from each unit differ in phase by an odd number of times 1/4 of the period, allowing for the cancellation of angular errors and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic sensors use magnetoresistive elements to detect the angle of an external magnetic field, then the sensor can detect rotational or linear position, but the output signal waveforms become distorted causing errors in angle detection
Solution Approach 1:
The patent divides the detection system into multiple independent detection units, each with its own magnetoresistive elements and signal processing circuits. By segmenting the detection function across multiple units with different orientations, the system can process signals independently and combine results to cancel out distortions, thereby maintaining measurement precision despite waveform distortion in individual channels.
Solution Approach 2:
The patent employs detection units with different orientations of magnetoresistive elements relative to the external magnetic field. This asymmetric arrangement creates detection units that respond differently to the same magnetic field, allowing the system to exploit these differences to cancel out common-mode distortions and improve angle detection accuracy.
2Measurement precision
If the magnetic sensor uses two bridge circuits with phase-differing output signals to calculate the angle, then the angle can be determined from the output signals, but the design complexity increases due to optimization requirements
Solution Approach 1:
The patent designs detection units that can function independently yet contribute to a common measurement goal. Each detection unit with its specific orientation serves multiple purposes: it provides a measurement channel, contributes to distortion cancellation, and can operate independently for robustness. This multi-functionality reduces overall design complexity by avoiding the need for highly optimized complex interactions between components.
Solution Approach 2:
The patent varies the orientation parameters of magnetoresistive elements in different detection units while maintaining a systematic pattern. By changing these geometric parameters in a controlled manner, the system achieves distortion cancellation without requiring complex optimization of electrical characteristics, thereby reducing design complexity while preserving measurement precision.
3Measurement precision
If the external magnetic field has high intensity, then the magnetic sensor can detect the field direction, but the magnetization pinned layer direction varies causing waveform distortion
Solution Approach 1:
The patent introduces detection units with specific orientations that act as counterweights to the distortion caused by high-intensity magnetic fields. The asymmetric arrangement of magnetoresistive elements in different detection units creates signal components that oppose and cancel the distortion introduced by field intensity variations, thereby maintaining measurement precision despite the harmful effect of high-intensity field-induced magnetization variations.
Solution Approach 2:
The patent converts the harmful effect of high-intensity magnetic field distortion into a beneficial feature by exploiting the systematic variation in magnetization pinned layer directions across different detection units. This systematic variation, which would normally cause distortion, is instead utilized to create differential signals that cancel out common-mode distortion, transforming the harmful intensity-dependent effect into a useful distortion-cancellation mechanism.
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
This approach significantly reduces the angular error in detected angles by aligning the phase differences between the detection units, resulting in more precise measurements of the external magnetic field's orientation.
Implementation Method 1
Each bridge circuit detects the intensity of a component of the external magnetic field in one direction
Implementation Method 2
The magnetic sensor detects the angle that the direction of the external magnetic field forms with respect to a reference direction
Data Source
AI summary
A magnetic sensor includes a first detection unit and a second detection unit. The first detection unit calculates a first detection angle which is a detected value of a first angle that a direction of an external magnetic field in a first position forms with respect to a first direction. The second detection unit calculates a second detection angle which is a detected value of a second angle that the direction of the external magnetic field in a second position forms with respect to a second direction. The first detection angle includes a first angular error. The second detection angle includes a second angular error. The first angular error and the second angular error differ in phase by an odd number of times 1/2 of the error period.