Metal proximity detector for can sizing - has oscillator, coil and frequency comparator to determine dimensions of metal can

摘要

A metal detector is used to detect the presence of metal without contact. It is used to check the size of metal cans or boxes during their manufacture. The proximity metal detector has a coil (250) with a core (251) and a winding (252). The winding (252) is connected to an oscillator (254). A frequency comparator (255) is used to detect any change in frequency. The inductance of the coil (250) depends on the presence of metal and of the type of metal at proximity. The frequency interval of the comparator (255) is set to determine the length of the can at proximity to the detector coil (250).