Inductive Detector Winding Pitch Variation
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Solution Overview
Problem
High-resolution and high-accuracy inductive displacement detectors face challenges due to complex PCB constructions, including high production costs, magnetic field distortion, registration tolerance, limited substrate materials, and electromagnetic interactions, which degrade measurement performance and increase complexity.
Innovation Solution
The use of a laminar inductive detector with a winding arrangement featuring four loops in series with varying pitch distances and opposite magnetic polarity, along with two spaced resonant targets, allows for absolute position measurement with reduced complexity and cost, enabling smaller volumes and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple coarse, intermediate and fine pitch windings are used to achieve high accuracy measurement, then measurement precision is improved, but device complexity increases due to multiple windings, multiple pitches, multiple PCB layers and many plated via holes
Solution Approach 1:
The measurement function is segmented between a single multi-pitch winding and multiple resonant targets with fixed separations. The winding provides coarse position information through its varying pitch, while the target separations enable fine resolution through interference patterns, eliminating the need for multiple windings of different pitches
Solution Approach 2:
The invention transitions from a single-dimension approach (multiple windings along the measurement path) to a two-dimension approach by introducing resonant targets with fixed separations spaced along the measurement path. This adds a spatial dimension to the measurement system, enabling high resolution through the interference of electromagnetic fields from multiple targets
2Measurement precision
If multiple PCB layers and plated via holes are used to construct complex winding arrangements, then measurement accuracy is improved, but production cost increases
Solution Approach 1:
The complex multi-layer PCB construction is replaced by segmenting the measurement function across a single-layer winding and multiple resonant targets. This segmentation allows each component to be simpler and more cost-effective to manufacture while collectively achieving high measurement accuracy
Solution Approach 2:
The invention replaces expensive multi-layer PCB constructions with simpler, cheaper single-layer PCB technology. The resonant targets can be implemented as simple conductive structures that are inexpensive to manufacture, eliminating the need for costly plated via holes and multiple PCB layers
3Manufacturing precision
If plated via holes are used in multi-layer PCB constructions, then winding registration is achieved, but magnetic field distortion occurs which degrades measurement performance
Solution Approach 1:
The harmful plated via holes are extracted and removed from the design. Instead of using via holes to achieve winding registration, the invention uses a single-layer PCB construction where the winding pattern is directly printed on the copper layer, eliminating the source of magnetic field distortion
Solution Approach 2:
The winding pattern is copied directly onto the single-layer PCB copper surface using standard PCB printing techniques, eliminating the need for plated via holes. The resonant targets are similarly implemented as printed conductive patterns, reproducing the necessary electromagnetic structures without harmful via holes
4Device complexity
If a single coarse winding is used to reduce complexity, then device complexity is reduced, but measurement resolution is insufficient for high accuracy applications
Solution Approach 1:
The invention changes the pitch parameter of the winding along its length, creating a multi-pitch winding where the distance between adjacent loops varies. This allows a single winding to provide position information across a large range while maintaining sufficient resolution through the pitch variation pattern
Solution Approach 2:
Resonant targets with fixed separations act as intermediaries that enable fine resolution measurement. The interference patterns created by these spaced targets provide high-resolution position information that complements the coarse position information from the single multi-pitch winding
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 solution provides a compact, effective method for high-resolution and high-accuracy position measurement, reducing the need for coarse windings and minimizing the issues associated with complex PCB constructions, such as magnetic field distortion and electromagnetic interactions, while maintaining high measurement precision.
Implementation Method 1
The inductive coupling between the transmit and receive windings varies according to the position of the target
Implementation Method 2
two spaced resonant targets
Data Source
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AI summary
An inductive detector operable to measure displacement along a path comprises: a first inductive arrangement (1); a second inductive arrangement (2); said second inductive arrangement (2) being an inductive target spaced from said first inductive arrangement and extending along at least part of the measurement path; at least one of said inductive arrangements comprises a winding (1a, 1b, 1c) which extends along at least part of the measurement path; and said winding (1b, 1c) comprising at least four loops in electrical series; wherein adjacent loops have opposite magnetic polarity; and the pitch distance of said winding varies at least once along the measurement path.