Metal Detector Pickup Array for Target Discrimination
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Solution Overview
Problem
Existing metal detectors face challenges in reliably discriminating between valuable and worthless items, often producing false positives in wet conductive soils, and lack continuity in detection signals when stationary over targets.
Innovation Solution
A metal detector system with a spatially distributed pickup array of small coils and a perimeter coil, using alternating illumination fields and phase detection to provide a continuous, three-dimensional display of target location and depth, even when stationary, and audio cues for ferrous or non-ferrous identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional metal detectors use a single pickup coil array, then the device structure is simple, but the detection precision and ability to discriminate target types is insufficient
Solution Approach 1:
The pickup array is divided into multiple independently controlled coils arranged in a matrix pattern. Each coil can be individually energized and its signal independently processed, enabling spatial discrimination of target locations and improved target type identification through phase comparison between adjacent coils.
Solution Approach 2:
The patent transitions from a single-point detection approach to a two-dimensional array of pickup coils. This dimensional expansion provides spatial information about target location and enables comparison of signal phases across multiple coils to distinguish between different target types and reduce false positives.
2Adaptability or versatility
If metal detectors operate in wet conductive soils, then detection coverage is improved, but false positives increase due to environmental interference
Solution Approach 1:
Each pickup coil in the array has its own signal processing circuit that compares the phase and amplitude of signals from adjacent coils. This local comparison capability allows the system to distinguish between signals caused by actual metal targets and those caused by environmental factors like wet soil, thereby reducing false positives while maintaining detection coverage in challenging environments.
Solution Approach 2:
The system continuously monitors signal phases from multiple coils and uses this feedback to dynamically adjust detection thresholds and identify target types. By comparing relative phase shifts across the array, the system can adapt to varying environmental conditions and maintain high detection accuracy even in wet conductive soils.
3Measurement precision
If metal detectors use traditional single-frequency excitation, then the system is simple to operate, but the ability to discriminate different metal types is limited
Solution Approach 1:
The excitation system dynamically switches between multiple frequency components rather than using a single fixed frequency. This dynamic frequency variation allows the system to exploit different resonant frequencies of various metal types, improving discrimination capability. The controller adjusts excitation frequencies based on the detected signal characteristics to optimize target identification.
Solution Approach 2:
The patent changes the frequency parameter of the excitation signal across multiple discrete frequencies or frequency ranges. By varying the excitation frequency and analyzing how different metal types respond at each frequency, the system can identify target types based on their unique electrical characteristics and resonant behaviors.
4Measurement precision
If metal detectors provide continuous detection signal, then target location accuracy is improved, but the device complexity increases
Solution Approach 1:
The continuous detection function is segmented across multiple independent pickup coils, each contributing to the overall signal picture. By processing signals from individual coils and combining them through phase comparison, the system achieves continuous target location tracking without requiring a single complex processing system. Each coil's signal can be independently analyzed for target presence and position.
Solution Approach 2:
The patent replaces traditional mechanical or single-point detection methods with an electronic array system that provides continuous spatial information. The multi-coil array electronically maps the magnetic field distribution, enabling continuous target location precision through electronic signal processing rather than mechanical scanning or single-point measurement.
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
Enhances target detection accuracy by providing a continuous signal and clear discrimination between types of metal, reducing false positives and allowing precise location of targets in various soils and environments.
Implementation Method 1
The coil array may be operated to generate an alternating magnetic field in a selected area. Target object location information is sensed as changes in the magnetic field that is received in the coil array
Implementation Method 2
If an object or item including some electrically conductive material, which may be referred to as the target, is close to the coil, eddy currents will be induced in the target, thereby generating an alternating magnetic field of its own
Implementation Method 3
Target object location information is sensed as phase changes in the magnetic field that is received in the coil array
Data Source
AI summary
A metal detector system 30 for sensing target (e.g., metal) objects within soil or other strata includes a pickup head 36 carrying an excitation coil configured to generate an excitation signal to energize a target object 400 and uses a 2-D (e.g., planar, rectangular) array of pixel-receive coils configured within the pickup head to receive electro-magnetic energy from the energized target object. As the user moves the pickup head across the strata's surface, the pixel-receive coils sense relative motion between each pixel-receive coil and the energized target object, where motion is detectable as individually sensed changes in received signal levels among the pixel-receive coils. The metal detector system also includes a 2-D display 46 which depicts or visually represents the 2-D array of pixel-receive coils and generates a changing display of any sensed moving target object 60 in response to sensed changes in received signal levels among the pixel-receive coils.