Contactless IC card, also known as radio frequency card, is composed of IC chip, induction antenna, packaged in a standard PVC card, chip and antenna without any exposed part. Is a new technology developed in the world in recent years, it successfully combines radio frequency identification technology and IC card technology, ending the problem of passive (no power in the card) and contactless, 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 5-10cm), and the data is read and written through the transmission of radio waves
operating principle
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The RF reader sends a set of fixed frequency electromagnetic waves to the IC card, and there is an LC series resonant circuit in the card, whose frequency is the same as that emitted by the reader. In this way, the LC resonant circuit resonates under the excitation of the electromagnetic wave, so that there is a charge in the capacitor. At the other end of this charge, there is a single-pass electronic pump, which sends 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, transmitting the data in the card or accepting the data of the reader.
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Emission principle
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The non-contact IC card and the card reader are read and written through radio waves. The communication frequency between the two is 13.56MHZ. The non-contact IC card itself is a passive card, when the reader reads and writes the card, the signal sent by the reader is composed of two parts: one is the power signal, which is received by the card and generates an instant energy with its own L\/C to supply the chip to work. The other part is the instruction and data signal, commanding the chip to complete the data reading, modification, storage, etc., and return the signal to the reader to complete a read and write operation. The reader is generally composed of a single chip microcomputer, a dedicated intelligent module and an antenna, and is equipped with a communication interface with the PC, a print port, an I\/O port, etc., in order to be applied to different fields.