| 摘要 |
Apart from the unit which has the card holder, the other units are arranged as receivers or transmitters for passages which limit a specific area containing the computer or apparatus. The unit which contains the card holder is arranged to be activated, as a transmitter or a receiver, when the card is removed from it. An alarm is activated if a person, carrying an activated card holder, is detected in their passage by the other unit. The units can communicate with infrared light, radio waves, and incorporate a resonator. The card is a so-called smart card, which is also usable as an identity card or an authorisation card. The alarm is transmitted by the unit which contains the card holder. |
