Magnetic Shift Lever Switch With Orthogonal GMR Position Sensing
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Solution Overview
Problem
Existing magnetic detection systems for position sensing, such as those using MRE or GMR elements, face challenges in accurately detecting multiple positions with redundancy and reliability, often requiring multiple bias magnets and complex configurations to achieve precise position detection.
Innovation Solution
A magnetic detection type switch employing two magnetic detection units with orthogonal sensitivity axes, each comprising GMR elements with a self-pin stop type fixed magnetic layer structure, allowing for the detection of six positions by utilizing the differential resistance changes in response to external magnetic fields, and incorporating redundancy for fault detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple bias magnets and MRE elements are arranged to detect multiple positions, then position detection capability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple detection functions into a single magnetic detection unit by arranging four GMR elements in a specific configuration. This unit can detect multiple positions (including neutral position) without requiring separate bias magnets for each position, thereby reducing overall device complexity while maintaining position detection capability.
Solution Approach 2:
The magnetic detection unit is designed to perform multiple functions: detecting neutral position, detecting shift positions, and providing redundancy for fault detection. This multi-functional design eliminates the need for separate detection systems for each function, reducing device complexity while improving measurement precision.
2Reliability
If redundancy information is combined among multiple magnetic detection units, then reliability and fault tolerance are improved, but device complexity increases
Solution Approach 1:
The patent divides the detection system into multiple magnetic detection units, each capable of independent operation. By segmenting the system this way, redundancy is achieved through parallel independent units rather than through complex interconnections, maintaining reliability while controlling device complexity.
Solution Approach 2:
The patent uses different sensitivity axis orientations (orthogonal directions) for different GMR elements within the same detection unit. This parameter change approach allows multiple detection functions to be achieved within a single compact unit, providing redundancy without increasing overall device complexity.
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 enables accurate detection of multiple positions with enhanced redundancy, improving reliability and fault tolerance, and simplifies the formation of magnetoresistance effect elements on a substrate, thereby enhancing the overall position sensing capability.
Implementation Method 1
each comprising GMR elements with a self-pin stop type fixed magnetic layer structure, allowing for the detection of six positions by utilizing the differential resistance changes in response to external magnetic fields
Data Source
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AI summary
A magnet (7) (movable portion (5)) is supported to be movable between four positions ((1) to (4)) that are divided by a first virtual line (A) and a second virtual line (B) which are orthogonal to each other in a plane. A magnetic detection unit (10) is fixedly supported at a crossing position (C) of the first virtual line (A) and the second virtual line (B). The magnetic detection unit (10) has a first magnetoresistance effect element (11) and a second magnetoresistance effect element (17), and sensitivity axis directions (PX2) and (PY2) of the respective magnetoresistance effect elements (11) and (17) are orthogonal to each other. When the magnet (7) is moved between the four positions ((1) to (4)), the four positions ((1) to (4)) can be detected based on a detection output obtained from each of the magnetoresistance effect elements (11) and (17).