Reed switch: A circuit switching element controlled by magnetic field signal, without magnetic disconnection, the glass tube is fragile. Used for switch detection of flip or slide switch. If it is detected that the mobile phone has closed the flip, the software will close the functions covered by the flip, such as keyboard. You can also use the menu to set the flip cover to open the answer and turn on the hang-up function. If the dry spring fails, the above-mentioned function fails. Reed switch is a passive electronic component, which is widely used in various communication devices. It is a circuit switching device controlled by magnetic field signal, also called "magnetic reed tube". Reed switchs shell is usually a sealed glass tube, in which there are two iron elastic reed plates, and the glass tube is also filled with an inert gas called rhodium. At ordinary times, the two reeds in the glass tube are separated. When a magnetic substance approaches the glass tube, under the action of magnetic field lines, the two reeds in the tube are magnetized to attract and contact each other, so that the circuits connected with the two pins are connected. After the external magnetic force disappears, the two reeds are separated due to their own elasticity, and the circuit is also disconnected. In practice, permanent magnets are usually used to control whether the two metal pieces are connected or not, so they are also called "magnetrons".