Inductive Position Sensing Layout With Shielded Tracks Against Crosstalk
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Solution Overview
Problem
Existing inductive position measuring devices face challenges in achieving high measuring accuracy and are susceptible to crosstalk errors, particularly when measuring relative positions with angular or rotational movements.
Innovation Solution
The device incorporates a scanning element with offset receiver tracks and division tracks on a scale element, featuring alternating ridges and gaps, along with a shielding rib to minimize crosstalk and enhance measurement precision, utilizing a vernier principle for absolute position determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If receiver tracks are arranged close together to reduce device size, then device compactness is improved, but crosstalk between receiver tracks increases
Solution Approach 1:
A shielding rib made of electrically conductive material is positioned between adjacent receiver tracks to act as an electromagnetic shield. This intermediary structure blocks or redirects electromagnetic fields from one receiver track from interfering with adjacent tracks, thereby reducing crosstalk while allowing the receiver tracks to remain in close proximity for device compactness.
2Measurement precision
If multiple receiver tracks are used to improve measurement accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The measurement function is segmented across multiple receiver tracks, each responsible for detecting signals from specific division tracks. By dividing the measurement task across multiple specialized receiver tracks with distinct periodic patterns, the system achieves higher measurement accuracy through signal differentiation while maintaining manageable device complexity through functional segmentation.
Solution Approach 2:
The patent introduces a second direction (Y-direction) orthogonal to the primary measurement direction (X-direction) by offsetting receiver tracks and division tracks in this second direction. This dimensional approach allows multiple receiver tracks to be arranged without overlapping in the measurement direction, enabling improved measurement accuracy through multi-track operation while controlling device complexity through spatial organization in two dimensions.
3Object-generated harmful factors
If receiver tracks are offset in the second direction to reduce crosstalk, then crosstalk is reduced, but device area increases
Solution Approach 1:
Receiver tracks are offset from each other in a second direction (Y-direction) that is orthogonal to the primary measurement direction (X-direction). This dimensional offsetting reduces electromagnetic coupling and crosstalk between adjacent receiver tracks. The scale element similarly uses division tracks offset in the second direction, creating a two-dimensional grid arrangement that minimizes interference while controlling the overall device footprint.
Solution Approach 2:
Shielding ribs are positioned between offset receiver tracks to provide additional electromagnetic shielding. These intermediary conductive structures further reduce crosstalk between receiver tracks that are offset in the second direction, enabling the system to achieve low crosstalk levels without requiring excessive spacing between tracks, thereby controlling device area.
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-precision relative position measurement with reduced crosstalk, ensuring accurate determination of both linear and angular positions, minimizing moiré errors and optimizing measurement accuracy.
Implementation Method 1
When a time-varying electrical excitation current is applied to the excitation conductor, signals dependent on the relative position are generated in the receiver coils or conductors during the relative movement between the scale element and the scanning element
Data Source
Figure 1~3
Figure 4~5
Figure 6~7
AI summary
The invention relates to an inductive position measuring device comprising a scale element (2) and a scanning element (1) movable relative thereto. The scanning element (1) has an excitation line (1.6), a first receiver track (1.1), and a second receiver track (1.2). The scale element (2) has a carrier layer (2.3) made of a first electrically conductive material, a first graduation track (2.11), and a second graduation track (2.12). The first division track (2.11) and the second division track (2.12) are arranged on the carrier layer (2.3) and formed from alternating webs (2.111, 2.121) and gaps (2.112, 2.122), wherein the webs (2.111, 2.121) are made of a second electrically conductive material that differs from the first material of the carrier layer (2.3). A shielding web (2.16) made of electrically conductive material is arranged between the first division track (2.11) and the second division track (2.12).