Multi-Frequency Proximity Sensor With PCB Spiral Inductor Sensing
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Solution Overview
Problem
Conventional inductive proximity sensors suffer from limited sensing distance range, electromagnetic interference susceptibility, and signal jamming issues, as well as requiring manual tuning and being sensitive to the material type of the target object.
Innovation Solution
The development of a proximity measuring transducer that utilizes an electromagnetic field perturbation principle with multiple frequencies and advanced coil structures, such as planar spiral inductors, to extend the sensing distance and enhance immunity to electromagnetic interference, allowing the sensor to operate with any material type and resist jamming signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inductive proximity sensors use wire-wound ferrite loaded coil bobbins to generate a magnetic field, then the sensor can detect metallic targets, but the sensing distance range is limited and the device requires hand tuning for repeatable operation
Solution Approach 1:
The patent replaces the conventional wire-wound ferrite loaded coil bobbin structure with planar spiral inductors fabricated using printed circuit board (PCB) techniques. This substitution eliminates the need for manual winding and hand tuning, enabling automated manufacturing while extending the sensing distance range through optimized planar geometry and ferrite loading patterns.
Solution Approach 2:
The patent modifies the inductor structure by changing from three-dimensional wire-wound coils to two-dimensional planar spiral configurations. This parameter change, combined with strategic ferrite material placement and loading, optimizes the magnetic field distribution to extend sensing distance while maintaining manufacturability through standard PCB fabrication processes.
2Reliability
If conventional proximity sensors use static magnetic fields for sensing, then the structure is simple, but the sensor is susceptible to electromagnetic interference and signal jamming
Solution Approach 1:
The patent transitions from static magnetic field sensing to dynamic electromagnetic field perturbation techniques. By using alternating current to generate time-varying electromagnetic fields and detecting perturbations caused by target objects, the system achieves immunity to electromagnetic interference and signal jamming while maintaining practical device complexity through integrated circuit implementation.
3Measurement precision
If conventional inductive proximity sensors use planar spiral inductors to extend sensing range, then the sensing distance increases, but the sensor remains susceptible to electromagnetic interference effects and signal jamming
Solution Approach 1:
The patent employs composite structures combining planar spiral inductors with strategically placed ferrite materials. This composite approach extends the sensing distance range through enhanced magnetic field distribution while simultaneously providing shielding effects that reduce susceptibility to electromagnetic interference and signal jamming.
Solution Approach 2:
The patent converts the potential vulnerability to electromagnetic interference into a benefit by using electromagnetic field perturbation techniques. The same electromagnetic fields that could cause interference are utilized to detect target objects through their perturbing effect, thereby achieving immunity while extending sensing range.
4Adaptability or versatility
If conventional proximity sensors are designed for specific target materials, then the sensing performance is optimized for that material, but the sensor cannot operate with different material types
Solution Approach 1:
The patent designs the planar spiral inductor with ferrite loading to create a universal sensing mechanism that can detect perturbations in electromagnetic fields caused by various material types including metals, semiconductors, and insulators. This universal design maintains adequate sensing performance across different materials by relying on the fundamental electromagnetic interaction rather than material-specific properties.
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
The solution significantly increases the sensing distance range, provides immunity to electromagnetic interference, and allows the sensor to operate with any material type, reducing manufacturing costs and improving performance while resisting jamming signals.
Implementation Method 1
an electromagnetic (EM) field responsive component structure that produces an EM field in response to an applied radio frequency signal, and wherein the target whose proximity is to be measured is positioned such that it perturbs the EM field
Data Source
AI summary
Disclosed herein is a sensor having an extended sensing distance range beyond conventional proximity sensors. The sensor includes an electrical component structure having a topology in which current is concentrated close to a periphery of the electrical component to produce an extended sensing field. A frequency adjustment circuit can be used to control a frequency of the sensing field to avoid jammers or other interfering signals.