Hybrid Magnetic Optical Encoder for Precision Position Sensing
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Solution Overview
Problem
Conventional encoders are sensitive to positional deviations and environmental pollution, requiring precise assembly and being prone to signal interference, which limits their precision and robustness in high-precision applications.
Innovation Solution
The encoder integrates magnetic and optical sensing assemblies to obtain absolute position signals, with the optical sensing assembly featuring phased-array incremental light-receiving regions and patterns, and the magnetic sensing assembly capable of offset placement, enhancing precision and resistance to environmental factors while allowing for easier assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical encoder uses conventional Gray code or M-code with light emitter and receiver on the same side, then the absolute position information can be obtained, but the encoder becomes extremely sensitive to positional deviation between sensor and coded disc, requiring extremely accurate assembly and alignment
Solution Approach 1:
The patent divides the sensing function into two independent assemblies: magnetic sensing assembly for absolute position detection and optical sensing assembly for incremental position detection. This segmentation allows each assembly to be optimized independently, with the magnetic assembly providing robust absolute position information less sensitive to alignment errors, and the optical assembly providing high-resolution incremental data, thereby resolving the contradiction between measurement precision and ease of manufacture.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary for absolute position detection. Instead of using optical fields that are highly sensitive to positional deviations, the magnetic field serves as a mediator that provides absolute position information with much lower sensitivity to assembly and alignment errors, thus resolving the technical contradiction.
2Measurement precision
If the optical sensing region area is reduced to meet higher precision requirements, then the absolute position measurement precision is improved, but the encoder becomes more susceptible to environmental pollution such as oil, dirt or microparticles
Solution Approach 1:
The patent replaces the optical sensing system with a magnetic sensing system for absolute position detection. The magnetic sensing assembly uses magnetic fields instead of optical fields, making it insensitive to environmental pollution such as oil, dirt, or microparticles that would otherwise block or scatter light. This substitution maintains high measurement precision while eliminating vulnerability to environmental contaminants.
Solution Approach 2:
The patent creates a composite sensing system combining magnetic and optical sensing capabilities. The magnetic sensing assembly provides pollution-resistant absolute position detection, while the optical sensing assembly provides high-precision incremental position detection. This composite approach leverages the strengths of both sensing modalities to achieve both high precision and environmental robustness.
3Measurement precision
If the encoder uses conventional optical encoder architecture with light emitter and receiver on opposite sides of the coded disc, then the absolute position signal can be obtained, but the encoder thickness increases
Solution Approach 1:
The patent transitions from a conventional through-beam optical architecture (requiring light to pass through the disc from one side to the other) to a reflective optical architecture where the light emitter and receiver are positioned on the same side. The light reflects off the coded disc surface back to the receiver, effectively utilizing the z-dimension (thickness) more efficiently and reducing the overall encoder thickness while maintaining absolute position detection capability.
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 integration achieves high-precision absolute position sensing with improved robustness and pollution resistance, enabling thinner designs and broader assembly margins, thus addressing the limitations of conventional encoders.
Implementation Method 1
The magnetic sensing assembly is disposed on the circuit board and paired with the magnet, in order to perform magnetic sensing and obtain an absolute position signal when the magnet moves with respect to the housing
Implementation Method 2
The optical sensing assembly is disposed on the circuit board and paired with the optical coded disc having the first incremental pattern track and the second incremental pattern track, in order to perform optical sensing and obtain a first incremental position signal and a second incremental position signal
Data Source
AI summary
An encoder includes a magnet, an optical coded disc, a magnetic sensing assembly, an optical sensing assembly and a signal processing unit. The optical coded disc has a first incremental pattern track and a second incremental pattern track. The magnet and the optical coded disc are structurally coaxial and rotatable. The magnet sensing assembly senses the magnet rotation to obtain an absolute position signal. The optical sensing assembly senses the optical coded disc rotation to obtain a first incremental position signal and a second incremental position signal. The signal processing unit receives and integrates those signals to obtain a high precision absolute position information.