Metal detector is a special instrument for detecting metals. It uses the principle of electromagnetic induction. The generated magnetic field can induce eddy current in metal, which will generate magnetic field, affect the original magnetic field, and then give an alarm.
There are three groups of coils in the metal detector, namely the central transmitting coil and two equivalent receiving coils. An oscillator with a transmitting coil in the middle generates a high-frequency variable magnetic field. In the idle state, the induced voltages of the receiving coils on both sides cancel each other before the magnetic field is disturbed, thus achieving a balanced state.
Once the metal impurities enter the magnetic field area, the magnetic field is disturbed, and this balance is broken, and the induced voltages of the two receiving coils cannot be offset. The control system amplifies and processes the uncompensated induced voltage and generates an alarm signal (metal impurities are detected).
There are three main types of metal detectors:
Electromagnetic induction, X-ray detection and microwave detection are electronic instruments for detecting metals, which can be used in many fields.
Militarily, metal detectors can be used to detect metal mines; In the field of security, it can detect weapons and tools carried or hidden with you; Archaeologically, ancient tombs with buried metal objects can be detected; In engineering, it can be used to detect metal buried objects such as underground pipelines and pipelines; In mineral exploration, it can be used to detect and discover natural gold particles.
The first metal detector in the world was born in 193 1 year. It was invented by Dr. Gerhard R. Fisher in Fisher Laboratory in Palo Alto, California, USA. It was named metallographic microscope and patented.
Refer to the above contents: Baidu Encyclopedia-Metal Detector Baidu Encyclopedia-Metal Detector