Magnetic Scale Track Layout for Accurate Slider End Position Detection
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Solution Overview
Problem
Conventional position detecting devices for sliders experience reduced accuracy near the end portions of magnetic scales due to magnetic disturbances, leading to unstable magnetic information, which affects precise slider positioning.
Innovation Solution
The magnetic scale is configured with tracks where the magnetization start and end positions of some tracks are shifted opposite to the end portions of other tracks, ensuring stable magnetic information is used for accurate position detection, and the magnetic sensors are positioned to detect all tracks within a magnetically stable region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If magnetic information near end portions of the magnetic scale is used for position detection, then the detection range is extended, but the information accuracy deteriorates due to magnetic disturbance and instability
Solution Approach 1:
The magnetic scale is divided into multiple tracks (first track and second track) with different magnetization start and end positions. This segmentation allows the system to use different tracks at different positions: the first track is used in the magnetically stable region away from end portions, while the second track is used near end portions where the first track experiences magnetic disturbance. This resolves the contradiction by providing different track segments for different detection zones.
Solution Approach 2:
Different tracks are designed with different magnetization characteristics suited for different locations. The first track has magnetization optimized for stable regions, while the second track has magnetization optimized for end portions. The magnetic sensor selectively reads from the appropriate track based on position, ensuring high accuracy throughout the entire detection range while maintaining stability requirements.
2Loss of information
If the magnetic sensor detects magnetism of all tracks, then complete position information is obtained, but magnetic disturbance near end portions causes unstable detection results
Solution Approach 1:
The system dynamically selects which track to use based on the slider's position. The control unit determines whether the slider is in a magnetically stable region or near an end portion, and switches between using the first track or the second track accordingly. This dynamic adaptation ensures complete position information is always obtained while maintaining detection stability by avoiding magnetically disturbed regions.
Solution Approach 2:
The second track acts as an intermediary solution for end portion detection. When the slider approaches end portions where the first track becomes magnetically unstable, the system transitions to using the second track which has magnetization designed to provide stable signals in those regions. This intermediary track bridges the gap between maintaining information completeness and ensuring detection reliability.
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 high-accuracy detection of slider positions by stabilizing magnetic information near the end portions, enabling precise control and minimizing magnetic disturbances, thus enhancing the overall detection accuracy.
Implementation Method 1
a magnetic sensor that is provided in the conveyance unit and detects magnetism of the magnetic scale
Implementation Method 2
Magnetization start positions and magnetization end positions of some of the plurality of tracks are shifted
Data Source
AI summary
A conveyance device includes a slider, a conveyance unit, a magnetic scale for detecting a position of the slider, and a magnetic sensor for detecting magnetism of the magnetic scale. The magnetic scale includes a plurality of tracks arranged in parallel, and magnetization start positions and magnetization end positions of some tracks of the plurality of tracks are shifted to a side opposite to an end portion of the track from magnetization start positions and magnetization end positions of the other tracks.