Resonant-Circuit-Free Metal Detector for Stable Signal Detection
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Solution Overview
Problem
Metal detectors face inaccuracies due to temperature influences and component aging, especially when exposed to large temperature differences or used over long periods, leading to unreliable detection of metallic objects.
Innovation Solution
A detector design featuring a transmitter coil and a receiver coil without a resonant circuit, where the receiver coil is directly connected to an evaluation unit, allowing for accurate voltage measurement independent of temperature or component aging, and utilizing high inductance coils for enhanced sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a resonant circuit with coils is used to detect metallic objects, then the detection sensitivity is improved due to high oscillation amplitudes, but the measurement accuracy deteriorates because of temperature influences and component aging
Solution Approach 1:
The patent extracts the harmful resonant circuit component from the detection system. By eliminating the resonant circuit while maintaining the coil-based electromagnetic induction principle, the system retains detection sensitivity without suffering from temperature drift and component aging that affect resonant circuits. This is achieved by directly measuring the induced voltage in the receiver coil without requiring oscillation amplification.
2Power
If resonant circuits are used to amplify small excitations, then the oscillation amplitudes increase making changes easier to detect, but the system becomes sensitive to temperature changes and component aging
Solution Approach 1:
The patent converts the harmful effect of temperature sensitivity into a benefit by eliminating the resonant circuit entirely. Instead of trying to compensate for temperature effects in resonant circuits, the system uses direct electromagnetic induction where the induced voltage in the receiver coil is directly proportional to the rate of change of magnetic flux, providing inherent temperature stability while maintaining adequate signal levels for detection.
3Reliability
If resonant circuits are employed for metal detection, then the detection capability is enhanced, but the system requires frequent readjustment and tuning over time
Solution Approach 1:
The patent implements a self-service detection system where the receiver coil directly measures the induced voltage from the transmitter coil without requiring external tuning or readjustment. The system automatically maintains optimal detection performance because the induced voltage signal is inherently stable and does not depend on resonant frequency matching, eliminating the need for manual intervention to maintain detection capability.
4Measurement precision
If resonant circuits are used to improve signal detection, then the oscillation amplitudes are amplified, but the system complexity increases due to tuning requirements
Solution Approach 1:
The patent removes the complex resonant circuitry including oscillators, frequency tuners, and amplitude regulators from the detection system. By using direct electromagnetic induction with simple voltage measurement across the receiver coil, the system achieves adequate signal detection capability with minimal circuit complexity, eliminating the need for resonant frequency generation and maintenance.
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 design provides more accurate and reliable detection of electrically conductive and ferromagnetic materials by minimizing the influence of temperature and component aging, allowing for precise measurement of induced voltages without the need for parameter readjustment or exact tuning of oscillating circuits.
Implementation Method 1
The power supply is designed to provide an alternating voltage or an alternating current during operation... The evaluation unit is designed to detect a signal induced in the receiver coil
Implementation Method 2
If the receiver coil is positioned in a magnetic field, a voltage can be induced in the receiver coil when the magnetic field changes. The magnetic field can change, for example, when an electrically conductive material moves within the magnetic field.
Data Source
Figure 1~2
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AI summary
The invention relates to a detector (10) for detecting electrically conductive material. The detector (10) comprises at least a transmitter (11), which has a transmitter coil (12) and a supply source (13), a receiver (14), which has a receiver coil (15), and an evaluation unit (16). The transmitter coil (12) is connected to the supply source (13). The supply source (13) is designed to provide an alternating voltage or an alternating current during operation. The receiver (14) is designed as a resonant-circuit-free receiver. The receiver (14) is connected to the evaluation unit (16). The evaluation unit (16) is designed to detect a signal induced in the receiver coil (15).