U.S. Philips Corporation

Wilfried Petschenig

Werner Janesch

Bernhard Spiess

Siegfried H Arnold

Kuno Reis

In a transponder communication device (1) having a selector for the successive individual selection of transponders (2) the selector having interrogator (5) for generating at least one item of interrogation information (AFI) with which the transponders (2) can be interrogated to transmit answer information (AWI) in response to the interrogation information (AFI), and time-window generator (17) for generating a series of K successive time windows (ZF) and controller (20) for the time-window generator (17), which controller can activate the time-window generator (17) so as to generate the series F of K time windows (ZF) a number of times in succession, and evaluator (22) which cooperates with the time-window generator (17) and by which, depending on the occurrence of at least one item of answer information (AWI) transmitted to the transponder communication device (1) by a transponder (2) in response to interrogation information (AFI), a transponder (2) can be selected in at least one time window (ZF) in each series (F) of the series (F) of K time windows (ZF) generated a number of times in succession.

Transponder communication device for the contactless communication with

A transponder communication device has an interrogation signal generator for generating an interrogation signal, a transmitter for transmitting the interrogation signal to a number of transponders, and a receiver for receiving answers signal from transponders. A transponder has an interrogation signal detector, an answer signal generator, and a state setting controller for setting a state of the transponder. The transponder communication device selects a single transponder from the number of transponders. First, the transponder communication device transmits an initial interrogation signal is transmitted to all transponders when the transponders are in an active state. In dependence of answer signals received from the transponders, the transponder communication device transmits a standby setting signal to at least one transponder at a time to instruct the transponders to adopt a standby state. In the standby state the transponders wait until a single other transponders has been selected. Thereafter all unselected transponders are selected by first setting the unselected transponders into an active state, from the standby state. Selected transponders are set into a passive state until all transponders have been selected. Thereupon, the active state is restored for all transponders.

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Graz, Austria

Wilfried Petschenig