The contactless IC card is also known as the radio frequency card. It is composed of an IC chip and an induction antenna. It is packaged in a standard PVC card, and the chip and antenna have no exposed parts. It is a new technology developed in the world in recent years, and it has successfully combined radio frequency identification technology and IC card technology. It ends the problem of passivity (no power source in the card) and contactless, and it is a major breakthrough in the field of electronic devices. The card is close to the surface of the reader at a certain distance (usually 5-10mm), and the data is read and written through the transmission of radio waves.
The radio frequency reader sends a set of electromagnetic waves with a fixed frequency to the IC card. There is an IC series resonance circuit inside the card whose frequency is the same as the frequency emitted by the reader. Under the excitation of electromagnetic waves, the LC resonant circuit resonates so that the capacitor is charged. At the other end of the charge, a unidirectional electronic pump is connected to send the charge in the capacitor to another capacitor for storage. When the accumulated charge reaches 2V, the capacitor can be used as a power supply to provide working voltage for other circuits, and transmit data in the card or receive data from the reader.
The radio wave is used to complete the read and write operations between the contactless IC card and the card reader and the communication frequency between the two is 13.56MHZ.
The contactless IC card itself is a passive card. When the reader reads and writes to the card, the signal sent by the reader is composed of two parts: One part is the power signal. The signal is received by the card and it produces instant energy with its own L/C to supply the chip to work. The other part is the instruction and data signal, which instructs the chip to complete data reading, modification, storage, etc., and returns the signal to the reader to complete a read and write operation. The reader is generally composed of a single-chip microcomputer, a special intelligent module and an antenna. And it is equipped with a communication interface with a PC, a printer port, an I/O port, etc. so that it can be used in different fields.