Linear Displacement Absolute Encoder with Soft-Magnetic Strip
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Solution Overview
Problem
Magnetic grid displacement sensors have a limited detection distance and are costly due to the use of permanent magnet magnetic grids, making them unsuitable for long-distance displacement measurement in harsh environments.
Innovation Solution
A linear displacement absolute position encoder using a magnetoresistive sensor array and an encoding strip with recesses and protrusions, magnetized by a back magnet, to detect magnetic field information for position encoding, reducing costs by using a soft magnetic material and avoiding long-distance permanent magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If magnetic grid displacement sensor is used for long-distance displacement measurement, then detection distance is improved, but cost of permanent magnet magnetic grid becomes high
Solution Approach 1:
The patent replaces expensive permanent magnets with a back magnet (electromagnet) that can be turned on and off, and uses a soft magnetic material encoding strip instead of a permanent magnet magnetic grid. This substitution dramatically reduces cost while enabling long-distance detection capability.
Solution Approach 2:
The patent changes the magnetic material properties by using soft magnetic material for the encoding strip with recesses and protrusions, which can be magnetized by the back magnet to create the magnetic field pattern for encoding, replacing the need for permanent magnets.
2Reliability
If magnetic grid displacement sensor is used, then anti-pollution characteristics are improved, but detection distance is limited to within 10 meters
Solution Approach 1:
The patent replaces the mechanical contact-based magnetic grid sensor with a non-contact magnetic field detection system using magnetoresistive sensors and a back magnet, eliminating the 10-meter limitation while maintaining anti-pollution characteristics through non-contact operation.
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 encoder achieves long-distance displacement measurement with low cost, high accuracy, and durability, suitable for harsh environments, with a simple encoding mode and reduced size.
Implementation Method 1
the back magnet being used for generating a non-uniform magnetic field around the encoding strip so as to magnetize the encoding strip
Implementation Method 2
the magnetoresistive sensor array comprising magnetoresistive sensors in N rows and M columns, and the magnetoresistive sensor array being used for acquiring position encoding information of the encoding strip by detecting magnetic field information of the encoding strip
Implementation Method 3
The magnetoresistive sensor may be a linear magnetoresistive sensor, and the linear magnetoresistive sensor may comprise any one of a Hall effect sensor, an anisotropic sensor, a giant magnetoresistive sensor, and a tunnel magnetoresistive sensor
Data Source
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AI summary
Disclosed is linear displacement absolute position encoder (10) used for measuring displacement of a tested apparatus. The linear displacement absolute position encoder (10) comprising a base (100), a magnetoresistive sensor array (300), an encoding strip (200), and a back magnet. The encoding strip (200) is fixed on the base (100) and extends in the direction of a rail of the tested apparatus. The encoding strip is a magnetic material block having recess and protrusion for identifying encoding information of different positions. The magnetoresistive sensor array (300) is arranged between the encoding strip (200) and the back magnet in a non-contact manner. The back magnet is used for generating a non-uniform magnetic field around the encoding strip (300) so as to magnetize the encoding strip (200). The magnetoresistive sensor array (300) is used for acquiring the position encoding information of the encoding strip (200) by detecting magnetic field information of the encoding strip (200). The encoder (10) is low cost and can monitor large distances