Example Applications - RFID: Fundamentals and Applications in Contactless Smart Cards and Identification - page 350

Figure 13.18 The hotel safe with integral offline terminal can only be opened by an authorised
data carrier (reproduced by permission of (hotel-save is shown by the picture) Hafele GmbH,
D-Nagold)
13.4.3 Transponders
Access control using PVC cards has been around for a long time. Hole punched cards
were used initially, which were superseded by infrared passes (IR barcode), mag-
netic strip passes, Wiegand passes (magnetic metal strips), and finally smart cards
incorporating a microchip (Schmidhausler, 1995; Virnich and Posten, 1992). The main
disadvantage of these procedures is the inconvenience of the operating procedure due
to the fact that the cards must always be inserted into a reader the right way round.
Access control using contactless systems permits much greater flexibility because the
transponder only needs to pass a short distance from the reader antenna. Passes can be
made in the form of contactless smart cards, key rings, and even wristwatches.
A great advantage of contactless access control systems is that the reader is mainte-
nance-free and is not influenced by dust, dirt or moisture. The antenna can be mounted
'under plaster', where it is completely invisible and protected against vandalism. Hands-
free readers are also available for mounting in turnstiles or to increase convenience.
In these designs, the transponders do not even need to be removed from the pocket or
jacket clip.
Cat flaps operated by a transponder in the cat's collar represent another application
in the field of access control, as does the use of read-only transponders as anti-theft
sensors for opening or closing doors and windows (Miehling, 1996).