Magnetic Position Detector with Segmented Pole Arrangement
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Solution Overview
Problem
Magnetic position detectors with neighboring magnetic members having no space between them suffer from low detection accuracy due to a significant difference between the magnetic field in the sensor's stroke range and an ideal rotating magnetic field.
Innovation Solution
Separate arrangement of magnetic members with a magnetic-length rate of 40% to 60% allows for improved detection accuracy by creating a magnetic field that approximates an ideal rotating magnetic field, using rare-earth or neodymium magnets to ensure the necessary magnetic field strength is maintained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If magnetic members are arranged with no space between them, then the structure is compact, but detection accuracy deteriorates due to significant difference from ideal rotating magnetic field
Solution Approach 1:
The magnetic member is divided into multiple separate magnetic poles (first magnetic pole and second magnetic pole) with spaces between them, rather than forming a continuous magnetic structure. This segmentation allows the magnetic field to more closely approximate an ideal rotating magnetic field pattern, improving detection accuracy while maintaining reasonable structural compactness through controlled arrangement of discrete poles.
2Measurement precision
If magnetic members are separated with spaces, then detection accuracy improves by approximating ideal rotating magnetic field, but device complexity increases
Solution Approach 1:
Different magnetic poles are assigned different magnetic lengths (the first magnetic pole has a different magnetic length than the second magnetic pole), creating local variations in magnetic field strength and distribution. This local quality differentiation enables the separated magnetic poles to generate a magnetic field pattern that closely matches the ideal rotating magnetic field, achieving high detection accuracy through localized magnetic property optimization rather than uniform structure.
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 results in higher detection accuracy and allows for smaller magnetic members, leading to a lower-cost magnetic position detector with improved performance across varying stroke lengths.
Implementation Method 1
a spin-valve type magnetoresistive element, for example a spin-valve giant magnetoresistive element (SV-GMR) includes a ferromagnetic pinned layer whose magnetization direction is fixed to one direction, a nonmagnetic layer through which electric current mainly passes, and a ferromagnetic free layer whose magnetization direction is same as a direction of an external magnetic field (external magnetic flux)
Implementation Method 2
the magnetic member 801 is magnetized so that it alternately has north and south magnetic poles on its surface
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 2C~2D
AI summary
Magnetic members are arranged straight and are face to face with spin-valve type magnetoresistive elements. Magnetic pole faces thereof which can be face to face with the spin-valve type magnetoresistive elements have different magnetic polarities from neighboring magnetic pole faces. The magnetic members are arranged in equal pitch. Each magnetic member is separate from a neighboring magnetic member. X/P is from 40% to 60%, X is the length of each magnetic member along an arrangement direction of the magnetic members, and P is the arrangement pitch of the magnetic members.