First, the principle of door frame metal detector
Generates 3.5-4.95M sinusoidal oscillation from the crystal oscillator, divided by a frequency divider to a sine wave of about 7.8K. After power amplification by the transistor and the coil, the input coil (7-zone) enters the large coil for electromagnetic wave emission from the inside of the door. Area coils receive separately. After receiving, the received signal is compared with the reference signal. After the change is found, the output level of the acquisition card is changed. The card data of the six locations is scanned to determine the location of the metal and output is displayed.
Second, the structure of arched metal detetectors
1. Door structure: It consists of a large coil, 6 small coils, compensation coils and graphite.
2, chassis structure
Third, detection work process of walk-through metal detector
CPU detection → a group of infrared blocked → detect whether the acquisition card data changes → alarm → detect another set of infrared → reset re-probing. Does the security gate have electromagnetic radiation? Any electronic product has a certain amount of electromagnetic radiation. There is also a lot of electromagnetic radiation around us. For example, radio,
Television stations, mobile phone towers, high-voltage lines, computers, televisions, microwave ovens, induction cookers, mobile phones, and so on.
Compared to these electronic products,the electromagnetic radiation of the security door is minimal,Because Security door is weak magnetic field induction technology Surgery, the power is very small, much smaller than the power of the mobile phone when talking! Less radiation than computer monitors. So security door of electromagnetic radiation is safe