Planar Inductive Sensor Coil Architecture for PCB Layer Reduction
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Solution Overview
Problem
Conventional inductive position sensors with planar coil assemblies on multiple printed circuit board (PCB) layers are costly and space-consuming, necessitating a reduction in the number of PCB layers for improved reliability and efficiency.
Innovation Solution
A non-contact angular position sensor utilizing a planar coil assembly with at least one excitation coil and two sensing coils, where each sensing coil has clockwise and counter-clockwise winding portions, positioned on a single or dual PCB layers, with a rotatable inductive coupling element having a sector aperture to induce a time varying voltage for position sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If planar coils are spread across multiple PCB layers, then the required connections between layers can be established, but the cost and complexity of the inductive sensor assembly increases due to the need for numerous PCB vias
Solution Approach 1:
The patent transitions from a multi-layer PCB architecture to a planar single-layer architecture by redesigning the coil geometry. The excitation and sensing coils are arranged in the same plane with specific spatial relationships (excitation coil surrounding the sensing coils), eliminating the need for vertical connections through PCB vias. This dimensional reorganization maintains the required magnetic coupling while simplifying the manufacturing process and reducing costs.
2Reliability
If conventional axial windings on Ferro-magnetic core are used, then inductive position sensing is achieved, but the assembly is expensive and consumes considerable space
Solution Approach 1:
The patent replaces the traditional mechanical/Ferro-magnetic core structure with a planar printed circuit board implementation. The coils are fabricated directly on the PCB using conductive traces, eliminating the need for complex axial winding processes and Ferro-magnetic materials. This substitution maintains the inductive sensing function while dramatically reducing assembly complexity, cost, and space requirements.
3Ease of operation
If numerous PCB vias are used to connect PCB layers, then the required connections for multi-layer coil assembly are established, but the manufacturing cost increases
Solution Approach 1:
The patent extracts and eliminates the need for PCB vias by implementing all coil windings and electrical connections on a single PCB layer. The excitation and sensing coils are arranged in a planar configuration where all necessary electrical pathways are achieved through surface traces without requiring vertical inter-layer connections. This extraction of the via requirement directly reduces manufacturing cost and assembly 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 allows for a cost-effective and compact implementation of inductive position sensors on a reduced number of PCB layers, enhancing reliability and reducing manufacturing costs while maintaining accurate angular position sensing.
Implementation Method 1
an alternating current (AC) is injected into the excitation coil(s) which results in the generation of a time varying magnetic field in the vicinity of the excitation coil. The time varying magnetic field is sufficient to induce a time varying voltage in the sensing coils as a result of the mutual magnetic coupling between the excitation coil and the sensing coils
Implementation Method 2
The presence of the rotatable target within the time varying magnetic field changes the mutual magnetic coupling between the excitation coil and the sensing coils, relative to the position of the rotatable target. The change in mutual coupling between the excitation coil and the sensing coils alters the time varying voltage induced in the sensing coils
Data Source
AI summary
An angular position sensor comprising at least one planar excitation coil and at least two planar sensing coils positioned within an interior of the at least one planar excitation coil, each of the at least two planar sensing coils comprising a clockwise winding portion positioned opposite a counter-clockwise winding portion and a rotatable inductive coupling element comprising a sector aperture, the rotatable inductive coupling element positioned in overlying relation to the at least one planar excitation coil and separated from the at least one planar excitation coil by an air gap.