Rotation Angle Sensor Asymmetric Hall Element Arrangement
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Solution Overview
Problem
Existing rotation angle detection sensors face challenges in accurately specifying a rotation angle over a wide angle range, especially when Hall elements are deviated from a coaxial position with the rotation axis, due to positional deviations and uneven magnetization.
Innovation Solution
A rotation angle detection sensor is designed with a magnet body magnetized in an in-plane direction orthogonal to the rotation axis, featuring three Hall elements arranged offset from the axis, ensuring a phase difference in their outputs to securely specify rotation angles, along with a storage section for storing phase-related electric signals and a detection section for obtaining the rotation angle. The magnetization is set parallel to a straight line, and planes on the magnet body facilitate precise positioning and simplified manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall elements are arranged coaxially with the rotation axis, then measurement precision is improved, but device complexity increases and manufacturing precision requirements become more stringent
Solution Approach 1:
The patent deliberately positions Hall elements asymmetrically (non-coaxially) relative to the rotation axis. This asymmetric arrangement simplifies the device structure and reduces alignment complexity while maintaining accurate rotation angle detection through computational compensation methods.
Solution Approach 2:
The patent changes the positional parameters of Hall elements from coaxial to non-coaxial arrangement. By modifying this geometric parameter, the device complexity is reduced while the measurement precision is maintained through signal processing compensation for the offset positions.
2Device complexity
If Hall elements are arranged non-coaxially to simplify device structure, then device complexity is reduced, but measurement precision deteriorates due to positional deviation and uneven magnetization
Solution Approach 1:
The patent implements a feedback mechanism where the actual positions of Hall elements are measured and used to compute compensation values. This feedback loop corrects for positional deviations and uneven magnetization effects, maintaining measurement precision despite non-coaxial arrangement.
Solution Approach 2:
The patent introduces computational compensation as an intermediary between the non-coaxial Hall element arrangement and the rotation angle measurement. This intermediary processing step eliminates the direct negative impact of positional deviation on measurement accuracy.
3Adaptability or versatility
If the angle range is widened beyond narrow range, then adaptability is improved, but measurement precision deteriorates as Hall element output no longer corresponds one-on-one with rotation angle
Solution Approach 1:
The patent segments the rotation angle measurement range into multiple intervals, with different compensation strategies applied to each segment. This segmentation allows the system to maintain precise angle specification across a wide overall range by handling each sub-range optimally.
Solution Approach 2:
The patent transitions from a one-dimensional direct correspondence model to a multi-dimensional approach using multiple Hall elements arranged in specific patterns. This dimensional change enables unique angle identification across wide ranges by combining outputs from multiple sensors with different phase relationships.
4Ease of manufacture
If magnetization direction is made uniform over the whole periphery, then ease of manufacture is improved, but measurement precision deteriorates as it becomes impossible to specify magnetization direction for predetermined Hall element arrangement
Solution Approach 1:
The patent changes the magnetization pattern from completely uniform to a specific non-uniform distribution that creates distinct magnetic field characteristics at different angular positions. This parameter change enables precise angle detection while remaining compatible with standardized manufacturing processes.
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 configuration allows for accurate and stable rotation angle detection over a wide range, even when Hall elements are deviated, enhancing the sensor's precision and miniaturization capabilities while reducing labor in measurement and increasing accuracy.
Implementation Method 1
Each of the Hall elements outputs an electric signal in accordance with a direction and a magnitude of magnetic force lines
Data Source
AI summary
A rotation angle detection sensor includes a magnet body subjected to magnetization in an in-plane direction, a first Hall element and a second Hall element separated from each other and arranged offset to one of spaces divided by an imaginary plane including a rotation axis, and a third Hall element located in a position away from a straight line passing through the first Hall element and the second Hall element. A storage section stores a rotation angle that is related to electric signals having a phase difference therebetween, among electric signals of the first Hall element, the second Hall element, and the third Hall element. A detection section detects the electric signals of the first Hall element, the second Hall element, and the third Hall element and obtains from the storage section the rotation angle that is related to the detected electric signals.