Dual-Coil Proximity Sensor for Embedded Metal Interference
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Solution Overview
Problem
Proximity sensors fail to extend detection distance due to the influence of embedded metals, such as nuts and washers, which interfere with the detection of weak changes in reception waveforms.
Innovation Solution
The proximity sensor employs a configuration with a first and second concentrically disposed coil, a ferrite core, and magnetic and electric shields to suppress the influence of embedded metals, utilizing a reception circuit to detect voltage or current differences in both coils and a control circuit to enhance detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the detection distance is extended to avoid contact with the detection object, then the reliability is improved, but the embedded metal interferes with detecting weak changes in the reception waveform, worsening the measurement precision
Solution Approach 1:
The coil is divided into two separate coils (first coil and second coil) that are concentrically disposed. Each coil independently detects changes in the reception waveform, allowing the system to process multiple detection signals simultaneously. This segmentation enables differential processing to eliminate interference from embedded metals while maintaining extended detection distance.
Solution Approach 2:
A ferrite core is introduced as an intermediary component to guide and concentrate the magnetic field generated by the coils. The ferrite core enhances the magnetic coupling between the coils and the detection object, improving the detection of weak waveform changes at extended distances while the dual-coil configuration with differential processing eliminates embedded metal interference.
2Device complexity
If a single coil is used, then the device complexity is reduced, but the ability to suppress embedded metal influence and extend detection distance is insufficient
Solution Approach 1:
The single coil is segmented into two concentric coils with different detection characteristics. The first coil and second coil are positioned at different radii, creating distinct magnetic field distributions that respond differently to embedded metals versus detection objects. This segmentation provides the basis for differential processing to eliminate interference.
Solution Approach 2:
The solution transitions from a single-coil configuration to a two-coil concentric arrangement, adding a radial dimension to the coil configuration. This dimensional change creates multiple detection zones with different sensitivities, enabling the system to distinguish between embedded metal interference and actual detection objects through comparative analysis.
3Ease of operation
If the proximity sensor is embedded in nuts and washers, then the ease of operation is improved, but the embedded metal creates harmful interference with the detection waveform
Solution Approach 1:
The invention accepts that embedded metals will be present in the installation environment and converts this harmful factor into a manageable condition. By using differential detection between two concentric coils, the system identifies and eliminates the interference signal from embedded metals while preserving the detection signal from actual objects, thereby maintaining ease of embedding installation without detection interference.
Solution Approach 2:
The system changes the detection parameter from single-coil waveform detection to differential waveform comparison between two concentric coils. This parameter change allows the system to maintain the simple embedded installation while transforming the embedded metal from a harmful interference source into a distinguishable signal that can be filtered out through differential processing.
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 the sensor to effectively extend the detection distance by minimizing the impact of embedded metals, improving detection accuracy and reliability.
Implementation Method 1
The coil generates a magnetic field by an excitation current. The transmission circuit periodically applies a pulsed excitation current to the coil.
Implementation Method 2
The ferrite core guides a magnetic field generated from the coil.
Implementation Method 3
The reception circuit detects a voltage or a current generated in each of the first coil and the second coil by the magnetic field which is changed by the detection object.
Data Source
AI summary
Provided is a proximity sensor capable of sufficiently extending a detection distance by suppressing an influence of embedded metal. The proximity sensor includes a coil, a transmission circuit, a ferrite core, a reception circuit, and a control circuit. The transmission circuit periodically applies a pulsed excitation current to the coil. The coil includes a first coil and a second coil disposed concentrically with the first coil. The transmission circuit applies an excitation current to one of the first coil and the second coil. The reception circuit detects a voltage or a current generated in each of the first coil and the second coil by the magnetic field. The control circuit detects the detection object based on the change in the voltage or the current generated in each of the first coil and the second coil detected by the reception circuit.