Now read card technology is more and more arrogant, why do you say so, the reader will continue through the internal coil issued an electromagnetic field is excitation signal, when a induction card in the card reader device within, coil to the card is read card coil in the excitation signal of the induction produce weak electric current, as a card a small integrated circuit power supply, the card integrated circuit storage storage manufacturing is only input the number set identification number. Can generate current and identification numbers are attributed to the reader's coil, and now the development of induction type reader. Such things will be smooth, are attributed to the reader coil ah.