Rotation Detector With Offset Magnetoresistive Position Units
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Solution Overview
Problem
Existing rotation detectors require separate apparatuses to produce rotation detection and switch outputs, leading to difficulties in achieving high-precision switch outputs due to noise interference when the position detecting unit is offset from the magnet's center in the width direction.
Innovation Solution
A rotation detector using a single magnet with a rotating unit, an angle detecting unit, and position detecting units, where the magnet has end surfaces magnetized to different poles, and the angle detecting unit and position detecting units utilize magnetoresistive elements to produce both rotation and switch outputs based on a leakage magnetic field, with the position detecting units offset in the radial direction to minimize noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate apparatuses are used for rotation detection and switch output, then both rotation detection output and switch output can be produced, but device complexity increases
Solution Approach 1:
The patent combines the rotation detection function and switch output function into a single integrated apparatus. The angle detecting unit and position detecting unit share the same magnet and detection structure, allowing both rotation angle detection and position-based switch output to be generated simultaneously from one device, thereby reducing overall system complexity while maintaining dual functionality.
Solution Approach 2:
The detection apparatus is designed to perform multiple functions: it detects rotation angles continuously through the angle detecting unit and simultaneously generates discrete switch outputs when the magnet reaches predetermined positions through the position detecting unit. This multi-functional design eliminates the need for separate dedicated devices for each function.
2Ease of operation
If position detecting unit is offset from magnet center in width direction, then switch output can be generated, but measurement precision deteriorates due to noise interference
Solution Approach 1:
The patent employs different detection strategies for different functional requirements. The angle detecting unit uses magnetoresistive elements with sensitivity to magnetic field components in specific directions to achieve continuous angle detection. The position detecting unit uses magnetoresistive elements with different sensitivity characteristics to detect when the magnet reaches predetermined positions. Each detection unit is optimized for its specific function, allowing the position detecting unit to operate effectively even when offset from the magnet center.
Solution Approach 2:
The patent changes the operational parameters of the magnetoresistive elements based on their functional requirements. The angle detecting unit's magnetoresistive elements are configured to detect magnetic field components suitable for continuous angle measurement, while the position detecting unit's elements are configured to detect field components that generate clear switch outputs at predetermined positions. This parameter differentiation allows offset positioning without compromising 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 enables high-precision switch outputs with reduced error in position detection, allowing simultaneous production of rotation and switch outputs, even when the position detecting units are offset, thereby improving detection accuracy and reducing noise interference.
Implementation Method 1
The angle detecting unit includes a magnetoresistive element. The magnetoresistive element is operable to detect a change in angle of rotation of the rotating unit by detecting a leakage magnetic field from the magnet
Implementation Method 2
The magnetoresistive element has a resistance that depends on a change in intensity of a magnetic field component parallel to a direction of a tangent to the revolution path. The magnetic field component is included in a leakage magnetic field in the vicinity of the flat surface of the magnet
Data Source
AI summary
A rod-shaped magnet is mounted on a rotating unit. The rod-shaped magnet has end surfaces which are oriented in a rotating direction and are magnetized to different magnetic poles. An angle detecting unit including magnetoresistive elements is disposed so as to be offset in a radial direction of a revolution path of the magnet from the revolution path and is configured to detect a change in angle of rotation of the rotating unit by detecting a leakage magnetic field in the vicinity of a side surface of the magnet. Two position detecting units each include magnetoresistive elements and are configured to detect a change in orientation of a magnetic field in the direction of a tangent to the revolution path when facing the rod-shaped magnet and produce a switch output.