Reed switch is an abbreviation of the dry reed contacts a passive electronic switching elements, and has the advantages of simple structure, small size and ease of control, its shell is a sealed glass tube, the tubes are installed two iron elastic reed plate, but also filling called rhodium metal inert gas. In peacetime, the glass tube in the two reeds made of special materials are separated. When a magnetic substance close to the glass tube, in the role of the magnetic field lines, the pipe within the two reeds are magnetized to attract each other in contact, the reed will suck together, so that the junction point of the connected circuit communication. After the disappearance of the outer magnetic reed because of their flexibility and separate, the line is disconnected. Therefore, as a use of the magnetic field signals to control the line switching device, reed tube can be used as a sensor for counting the number, spacing, etc. (in the security system is mainly used for production of Menci, magnetic window), and also are widely used in a variety of communication devices. In practical use, usually with a permanent magnet control two metal sheet is turned or not, it is also referred to as "magnetron".
It has been applied in stored program control exchanges, photocopiers, washing machines, refrigerators, cameras, Disinfection cabinets, door magnets, window magnets, electromagnetic relays, electronic weighing devices, level meters, gas meters, water meters, etc.