Inductive Sensor Target With Modulated Conductive Patterns
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing inductive angle sensors face challenges in achieving high accuracy and reproducibility, particularly in narrow ring configurations, due to limitations in signal crosstalk and alignment errors.
Innovation Solution
The proposed solution involves a target for an inductive sensor with a plurality of M periodic sections and N conductive zones, where the conductive patterns are modulated in width to achieve two signals with different periodicity, allowing for increased measurement resolution and reduced alignment errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a narrow ring configuration is used for mounting in through-shaft arrangements, then space restrictions are satisfied, but signal crosstalk increases and measurement precision deteriorates
Solution Approach 1:
The encoder scale is divided into multiple independent tracks (first scale track and second scale track) with different periodicities. Each track is read by dedicated receiver coils, segmenting the measurement function to eliminate crosstalk while maintaining narrow ring configuration. This segmentation allows each track to contribute independently to the final angle measurement, resolving the contradiction between compact size and measurement precision.
Solution Approach 2:
Different regions of the encoder scale are designed with different properties: the first scale track has a first periodicity optimized for one receiver geometry, while the second scale track has a second periodicity optimized for another receiver geometry. This local differentiation allows each region to serve its specific measurement function without interfering with other regions, enabling high precision angle detection in a compact narrow ring format.
2Measurement precision
If multiple parallel Vernier tracks are used to increase measurement resolution, then angle detection accuracy improves, but signal crosstalk increases and device complexity worsens
Solution Approach 1:
The measurement function is segmented across two independent scale tracks with different periodicities, each read by dedicated receiver coils. This segmentation eliminates signal crosstalk between tracks while maintaining the Vernier measurement principle for high resolution angle detection. The first receiver geometry reads only the first scale track, and the second receiver geometry reads only the second scale track, ensuring no harmful crosstalk.
Solution Approach 2:
The patent introduces intermediate processing through the evaluation device, which combines measurements from the two independent tracks with different periodicities. This intermediary processing allows the system to achieve high measurement resolution through Vernier principle without requiring direct interaction between multiple tracks, thereby avoiding signal crosstalk while maintaining measurement precision.
3Device complexity
If conventional inductive sensor geometry is used, then device simplicity is maintained, but alignment errors increase and measurement precision deteriorates
Solution Approach 1:
The patent employs asymmetric design in the receiver geometries: the first receiver geometry has a first shape optimized for reading the first scale track with first periodicity, while the second receiver geometry has a second shape optimized for reading the second scale track with second periodicity. This asymmetric design allows each receiver to be optimally tuned to its specific track, minimizing alignment errors and maximizing measurement precision without significantly increasing overall device complexity.
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 enhances the accuracy and reproducibility of angle position detection, achieving a reproducibility of below 0.1° and an absolute accuracy better than 1°, while also being tolerant to geometrical alignment errors.
Implementation Method 1
An inductive sensor system comprises an exciter coil that couples an oscillating magnetic field in receiver coils
Implementation Method 2
a sensor that uses the principle of Eddy current formation to sense displacement. Eddy currents are formed when a moving or changing magnetic field intersects with a conductor
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Target (1300) for an inductive displacement sensor, comprising a plurality of N conductive zones (1310-3,1320-2) distributed along a measurement range having a dimension D tot in a direction C for providing a general encoder geometry. The target further comprising a plurality of M periodic sections ps for providing a fine encoder geometry, wherein each periodic section ps has a dimension of D tot /M in said measurement range and the plurality of periodic sections ps overlapping with the measurement range, wherein M and N are positive integer numbers and M is greater equal than 2*N. Each of the periodic sections ps is provided with a conductive pattern (1340-17, 1340-20) for providing a fine encoder pattern, wherein within the N conductive zones, the conductive patterns (1340-20) have a first width w1 in the direction C for covering partly the periodic section ps. Between the N conductive zones, the conductive patterns (1340-17) have a second width w2 in the direction C for covering partly the periodic section ps and the first width w1 is larger than the second width w2 for providing a general encoder pattern.