Inductive Encoder Scale Layout for Higher SNR Position Sensing
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Solution Overview
Problem
Existing inductive position encoders face challenges in achieving a balance of compact size, high resolution, accuracy, low cost, and robustness to contamination, as they often struggle to provide optimal combinations of these features.
Innovation Solution
The electronic position encoder design includes a scale with periodic signal modulating elements and a detector portion featuring a field generating coil and sensing elements, where the signal modulating elements have an average dimension DSME that is greater than the nominal sensing element width dimension DSEN, ranging from 0.55*W1 to 0.8*W1, enhancing signal-to-noise ratio and reducing error components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the signal modulating elements are made larger to improve signal-to-noise ratio, then measurement precision is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies parameter changes by optimizing the dimensional ratio between signal modulating elements and sensing elements to a specific range (0.55-0.8 times the spatial wavelength). This parameter optimization improves signal-to-noise ratio while maintaining manufacturability, resolving the contradiction between measurement precision and device complexity.
2Volume of moving object
If the encoder is made more compact to reduce size, then productivity and ease of operation improve, but measurement precision and accuracy deteriorate
Solution Approach 1:
The patent uses parameter changes by establishing specific dimensional relationships between components (signal modulating element size relative to spatial wavelength and sensing element width). These optimized parameters enable compact encoder design while preserving measurement precision, resolving the contradiction between encoder size and measurement accuracy.
3Measurement precision
If the sensing element width is increased to reduce error components, then measurement precision improves, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by defining the sensing element width as a specific proportion (0.55-0.8 times) of the spatial wavelength. This parameter relationship reduces error components and improves measurement precision while avoiding excessive device complexity, as the dimensions are determined by a clear mathematical relationship rather than arbitrary complex design.
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 improves detector signal characteristics, providing better signal-to-noise ratio and reduced error components, thus enhancing the encoder's performance in terms of accuracy and robustness.
Implementation Method 1
The field generating coil is configured to generate a changing magnetic flux in the interior area in response to a coil drive signal
Implementation Method 2
The set of sensing elements are configured to provide detector signals which respond to a local effect on the changing magnetic flux that is provided by adjacent signal modulating elements of the scale pattern
Data Source
AI summary
An inductive type position encoder includes a scale, a detector portion and a signal processor. The scale includes a periodic pattern of signal modulating elements (SME) arranged along a measuring axis, with a spatial wavelength W1. One type of SME in the pattern comprises similar conductive plates or loops. The detector portion comprises sensing elements and a field generating coil that generates a changing magnetic flux. The sensing elements may comprise conductive loop portions arranged along the measuring axis and configured to provide detector signals which respond to a local effect on the changing magnetic flux provided by adjacent SME's. In various implementations, the first type of SMEs have an average dimension DSME along the measuring axis direction that is greater than DSEN and at least 0.55*W1 and at most 0.8*W1, which provides advantageous detector signal characteristics.