Magnetic Position Sensor Using Stepped Detection Regions
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Solution Overview
Problem
Conventional position sensors struggle to accurately detect the position of a detection body made of magnetic material, particularly when the detection body has valley portions, as the magnet inside the detecting unit is not effectively affected by these portions, leading to potential missed detection.
Innovation Solution
A position sensor comprising a detecting unit with a magnet generating a bias magnetic field and a detecting element, along with a signal processing unit that compares detection signals with threshold values to identify the position of the detection body based on the magnitude relationship between the signals and thresholds, effectively determining the presence or absence of the detection body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional position sensor uses a magnet and detecting element to detect the position of a magnetic detection body, then the position can be detected based on magnetic field changes, but the sensor fails to accurately detect valley portions of the detection body, leading to missed detection
Solution Approach 1:
The detection body is divided into multiple region portions (first, second, third region portions) with different magnetic field characteristics. Each region portion corresponds to a specific detection signal range, allowing the sensor to detect different positions through segmented magnetic field regions rather than relying on continuous surface features that may include undetectable valley portions.
Solution Approach 2:
The invention changes the magnetic field parameters by introducing a bias magnetic field from a dedicated magnet and utilizing different magnetic permeability regions. The detection signals are generated based on changes in magnetic field parameters (flux density, direction) as the detection body moves through different region portions, enabling reliable detection without depending on valley portion geometry.
2Ease of manufacture
If the detection body has valley portions that are not effectively detected by the magnet, then the structure can be simplified, but the detection reliability deteriorates due to missed detection
Solution Approach 1:
The detection body is segmented into distinct magnetic field interaction regions (first, second, third region portions) with different magnetic permeability characteristics. This segmentation allows the body to maintain simple geometry while ensuring that each region produces a distinct magnetic field signature detectable by the sensor, eliminating the need for complex valley portion features.
Solution Approach 2:
Instead of relying on geometric features like valley portions, the invention uses parameter changes in magnetic permeability across different regions of the detection body. This approach maintains structural simplicity while ensuring reliable detection through distinct magnetic field responses from each region portion.
3Ease of operation
If the sensor relies on magnetic field changes from the detection body, then contactless detection is achieved, but the detection fails when the detection body is absent or has non-detectable features
Solution Approach 1:
A bias magnetic field is preliminarily established by the magnet before the detection body arrives. This preliminary magnetic field interacts with the magnetic regions of the detection body to generate detectable signal changes. When the detection body is absent, the lack of interaction with the bias field produces a distinct signal pattern, enabling reliable detection of both presence and absence states.
Solution Approach 2:
The invention uses parameter changes in the magnetic field (presence/absence of detection body, different magnetic permeability regions) to generate distinct detection signals. The bias magnetic field serves as a reference parameter that interacts with the detection body's magnetic regions, creating reliable signal differentiation between presence and absence states without requiring physical contact.
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 proposed solution enables accurate detection of the detection body's position, including when it is missing, by generating distinct detection signals that differentiate between the presence of the body's region portions and the absence of the magnetic field influence, thereby preventing missed detection.
Implementation Method 1
a magnet that generates a bias magnetic field and a detecting element to which the bias magnetic field is applied
Implementation Method 2
a detecting element to which the bias magnetic field is applied. The detecting unit generates detection signals corresponding to a plurality of ranges aligned in one direction along a moving direction of the detection body, based on a change in the magnetic field constantly received by the detecting element from the detection body
Data Source
AI summary
A detecting unit generates detection signals corresponding to a plurality of ranges aligned in one direction along a moving direction of a detection body, based on a change in the magnetic field constantly received by a detecting element from the detection body. A signal processing unit acquires a detection signal from the detecting unit, compares the detection signal with a threshold value, and identifies a position of the detection body as a position of any one of a plurality of ranges based on a combination of a magnitude relationship between the detection signal and the threshold value. A detection body has a plurality of region portions corresponding to a plurality of ranges. The plurality of region portions are configured to be connected stepwise in the moving direction of the detection body within a plane of a detection surface facing the detecting unit of the detection body.