Oscar Studios Retrospective
The inspection principle of the metal security gate is that when passing through the inspection gate, a magnetic field will occur in the coil around the gate. If it encounters the metal carried by a person, a current will be formed on the metal surface to generate a magnetic field in the opposite direction. Then the metal security gate will sound if it detects this magnetic field in the opposite direction.
Metal security gates can alarm metal objects that pass by because sensors on both sides of the door panels can emit and receive alternating electromagnetic fields. When metal conductors are encouraged by alternating electromagnetic fields, eddy currents occur in the metal conductors, and this current A magnetic field with the same frequency but opposite direction to the original magnetic field is emitted.The metal explorer checks whether the eddy current signal is present to find out whether there is a metal object nearby.
The transmitter encourages electromagnetic waves, and the receiving sensor receives the signal of the metal object. The receiving sensor detects the signal generated by the eddy current, and then undergoes a series of expansion processing of the circuit. When the signal amount reaches the set value, the acousto-optic method is adopted. An alarm has occurred.
In today's world market, there are two types of electromagnetic field emission signals that security gates have prevailed:
1.Sine wave: The advantages of the sine wave transmission method are simple signal processing, low cost, and high sensitivity; the drawback is simple interference.
2.Pulse wave: The pulse emission method is opposite to the sine wave emission method.The signal processing is more messy and the cost is higher; the strength is the anti-interference ability.
3.The multi-location security gates produced in the domestic market now have their skills copied from one or two developers who have not done intellectual property protection in time, so they use the initial sine wave emission method. From the principle and In terms of signal processing methods, each company basically produces
Skills, skills, and materials tend to be homogenous.
Looking at all the domestic metal security gate companies, as long as few companies have real product development capabilities, some production companies because they are only copying products and do not truly grasp the precision and fixed strength of the transmitting and receiving coils (accepting sensors). Some skills such as sexuality, do not know what pulse to collect, sinusoidal emission signal, and also use the initial manual winding method, the winding tightness of the coil and the number of winding turns do not conform to industrial specifications, so users are using The situation of these companies' underreporting and misreporting is particularly serious. Therefore, it is almost incredible to want to balance the relationship between sensitivity and anti-interference ability, without deep production skills, skills and long time accumulation. .