Proximity card

Transponder cards (also Contactless smart cards ) combine two technologies for automatic identification and data capture together: Chip Cards and Radio Frequency Identification.

For some applications contact smart cards are not advantageous. How to perform short-term loss of contact, for example, triggered by vibrations, to errors in the processing. These disorders can also be caused by wear or contamination of the contacts occur and electrostatic discharge can damage the integrated circuit inside the card.

Avoiding these problems contactless smart cards, which are distinguished in Close Coupling Cards and Remote Coupling cards. Contactless smart cards are the Remote Coupling assigned cards if the distance between the smart card and a terminal for data transmission from a few centimeters moved up to about one meter.

To create particular makes the fact that large number of the functional elements accommodated in the only 0.76 mm thin card body. The problem of the power supply of the electronics can not be solved with batteries because they are not yet in this strength available. For a contactless card therefore have the following four issues:

• The power transmission to the power supply of the integrated circuit.
• The transmission of the clock signal.
• Data transmission to the IC card.
• The data transfer from the smart card.

An important criterion is the distance between the card terminal and the card since this only a few millimeters to about may be one meter. Contactless smart cards communicate without galvanic coupling with the terminal by inductive or capacitive coupling.

• Inductive coupling: The transfer takes place via a coil (open transformer ), eg Amplitude modulation. It can all the signals are transmitted.
• Capacitive coupling: The transfer takes place via conductive surfaces that are integrated in the chip and act as capacitor plates. It is suitable only for data transmission.

Comparison of various contactless smart cards

Contactless smart cards are designed for a service life of ten years. Rain, cold, heat, dirt or dust represent neither for the chip card yet for the reader a problem

The arrangement of a coil and a microchip in a contactless IC card is referred to as a transponder or tag. The design of a tag is by far not limited to smart cards, but provides only a subset of the numerous methods for identifying dar. with RFID

• Hardware
• Smart card