Shielded Dual-Coil Proximity Sensor for Embedded Metal Interference
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Proximity sensors fail to sufficiently extend detection distance due to the influence of embedded metals, which interfere with the detection of weak changes in reception waveforms.
Innovation Solution
A proximity sensor design incorporating a first and second concentrically arranged coil, a ferrite core, an electric shield, and a magnetic shield, which suppresses the influence of embedded metals by guiding magnetic fields and detecting changes in voltage or current through both coils, using 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, causing the detection to fail
Solution Approach 1:
The patent introduces an electric shield as an intermediary component between the coil and the embedded metal. This electric shield blocks or reduces the interference from the embedded metal, allowing the sensor to detect weak changes in the reception waveform caused by the detection object at extended distances without being corrupted by metal interference
Solution Approach 2:
The patent segments the coil into multiple coils (first coil and second coil) with different configurations. By comparing the reception waveforms from multiple coils, the system can distinguish between signals caused by the detection object and those caused by embedded metal, thereby maintaining detection precision at extended distances
2Measurement precision
If multiple coils are used to improve detection accuracy, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple coils and the electric shield into a single integrated sensor head assembly. This merging approach allows the system to achieve improved detection precision through multiple coils while avoiding the complexity of separate components, as everything is integrated into one unified structure that can be installed as a single unit
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 design effectively extends the detection distance by minimizing the impact of embedded metals, improving detection accuracy and reliability by distinguishing between signals from detection objects and embedded metals.
Implementation Method 1
The coil generates a magnetic field by an excitation current
Implementation Method 2
The ferrite core guides a magnetic field generated from the coil
Implementation Method 3
The electric shield has a bottomed cylindrical shape disposed outside the second coil in the radial direction. The electric shield includes a peripheral portion and a detection surface portion
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 first coil, a second coil, a transmission circuit, a ferrite core, a reception circuit, a control circuit, and an electric shield. The second coil disposed radially outside the first coil. The transmission circuit periodically applies a pulsed excitation current to at least one of the coils. The control circuit detects the detection object D based on the change in the detected voltage or current generated in at least one of the coils by the magnetic field. The electric shield is a press-molded product having a bottomed tubular shape disposed outside the second coil in the radial direction and having a peripheral portion and a detection surface portion in which a cut crossing a direction around an axis is formed.