Inductive Position Sensor Coil Layout With Fewer PCB Levels
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Solution Overview
Problem
Inductive sensors face high manufacturing costs and increased error rates due to complex PCB layouts and the use of receiving coils in O-shaped or C-shaped designs, which affect their sensitivity and interference immunity.
Innovation Solution
The receiving coils are arranged in a parallel configuration forming a receiving geometry with a space between them, reducing the number of PCB levels required and enhancing sensitivity and interference immunity by canceling out induced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If receiving coils are arranged in O-shaped design around the axis of rotation, then the error rate is reduced, but the number of PCB levels increases to at least six, increasing manufacturing complexity and cost
Solution Approach 1:
The receiving coil is divided into multiple segments distributed across different PCB levels. Each segment captures a portion of the magnetic flux, and their combined effect provides robust position detection while reducing the total number of required PCB levels compared to a continuous O-shaped design.
Solution Approach 2:
The patent transitions from a two-dimensional planar coil design to a three-dimensional multi-level PCB structure. Receiving coil segments are positioned at different heights (Z-dimension) on the PCB, allowing magnetic flux capture from multiple levels simultaneously, which reduces the overall complexity while maintaining error reduction benefits.
2Device complexity
If receiving coils are arranged in C-shaped design, then the number of PCB levels is reduced, but the error rate increases
Solution Approach 1:
The receiving coil is segmented into multiple sections distributed across fewer PCB levels compared to O-shaped design. These segments are strategically positioned to maintain adequate error reduction capability while simplifying the overall PCB structure and reducing manufacturing complexity.
Solution Approach 2:
Different segments of the receiving coil are positioned at different PCB levels with optimized local configurations. This allows each segment to contribute effectively to error reduction while the overall structure maintains reduced complexity compared to full O-shaped designs.
3Manufacturing precision
If receiving coils are laid with angle of rotation greater than 180 degrees, then the receiving geometry is optimized, but the production technology becomes suboptimal
Solution Approach 1:
The patent utilizes the third dimension (vertical stacking on multi-level PCB) to achieve the required receiving geometry without requiring large in-plane rotation angles. This reduces the complexity of trace routing and manufacturing while maintaining the necessary magnetic flux capture capability.
Solution Approach 2:
The receiving coil is divided into segments that can be positioned at standard PCB angles (0°, 90°, etc.) on different levels, avoiding the need for complex non-standard angle routing. This simplifies production while achieving the required geometric properties for accurate position detection.
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 reduces manufacturing costs and error rates while increasing sensitivity and immunity to electromagnetic interference, allowing for more precise position detection.
Implementation Method 1
the exciter coil being arranged to induce a signal in each receiving coil based on the coupled AC voltage signal
Implementation Method 2
a movable coupling element which influences the strength of the inductive couplings between the exciter coil and the receiving coils as a function of the position to be detected
Data Source
AI summary
An inductive sensor for detecting a position. In one example, the sensor includes an oscillator circuit which generates an AC voltage signal and couples it into an exciter coil, and a pair of receiving coils including first and second receiving coils which each form a repeating loop structure and whose arrangement forms a receiving geometry. The exciter coil is arranged to induce a signal in each receiving coil based on the coupled AC voltage signal. An evaluation circuit outputs a sensor signal that depends on the position to be detected, based on the signals induced in the receiving coils, and a movable coupling element influences the strength of the inductive couplings between the exciter coil and the receiving coils as a function of the position to be detected. The receiving coils are located in a geometrical position having an intermediate space between them and are electrically connected to each other.