Structure
1, door structure: from a large coil, 6 small coil, compensation coil and graphite.
2, chassis structure AnJianMen
3, the detection workflow CPU detection →a group of infrared detection is blocked→ blocked a group of infrared detecting whether each data acquisition card change →alarm→Another group of infrared detection probe→reset again.
Detected by the detection principle is in the door, the door around the coil generates a magnetic field, then hit the back yard of the metal in your pocket will form around the metal surface to produce a current in the opposite direction of the magnetic field. Then the metal detector will sound if the detected magnetic field in the opposite direction.
Metal detector capable of generating metal objects by the police, is due to both sides of the door that has the energy to transmit and receive alternating electromagnetic field sensors. Metal conductor by alternating electromagnetic field when energized,
Generate eddy currents in the metal conductor, and the current is also launching an original field of the same frequency but in the opposite direction of the magnetic field, is through the metal detectors to detect the presence or absence of the vortex signal to discover the existence of nearby metal objects. Excited by the transmitter emits electromagnetic waves of the received signal by the receiving metal sensor, the sensor receives the detection signal generated by eddy currents taken out, and then through a series circuit of enlargement processing, when the signal reaches the set value, i.e. the amount of light in the form of sound alarm.
The current international market, security doors, there are two popular use electromagnetic emission signal mode:
1, the sine wave: sine advantages emission mode is that the signal processing is relatively simple, low cost, high sensitivity; disadvantage is susceptible to interference.
2, pulse: pulse emission mode with sine wave emission opposite way, signal processing more complex and costly; the advantage of strong anti-jamming capability.
Now the domestic market produced more regional security doors, its techniques are not done in time from the first one or two manufacturers in the development of intellectual property protection copied out, so is the use of the original sine wave transmission. From theory and signal processing is concerned, various basic production techniques, technology, materials and more homogeneous. Looking at the entire domestic production of metal detector gate enterprises, only a very small part of the business with a real product development capabilities,Some production companies because they are only generic products, and did not really grasp the transmitting and receiving coils (receiving sensor) technology precision and robustness of the fixed part of the core, do not know what section of the acquisition pulse, sine the transmitted signal, and also original manual winding method, winding tension and winding turns of the coil does not meet industry standards, so users omission in the use of these products in the process of enterprises, fiddling phenomenon is particularly serious. So you want to be well balanced sensitivity and anti-jamming capability relationship between the two, no superb production process, technology and years of experience is almost unimaginable.
Above is the principle of the security gate of a brief introduction.