Electronic surveillance and identification
First Claim
1. A passive surface acoustic wave transponder device comprising electrical input and output connections, a substantially ominidirectional antenna generally coupled to said connections, a substrate having a surface of piezoelectric material, an electrode transducer contacting said surface of said substrate and connected to said input to launch said wave upon selective electromagnetic excitation of said antenna by a field broadcast from a transceiver remote from said antenna and device, and a plurality of encoded transducers disposed along the path of said wave for reflection of echoes thereof to said output without electrodes and conversion of said wave to a voltage at said encoded transducers.
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Accused Products
Abstract
An electronic article surveillance and identification system employing a transceiver (10,11) for broadcasting an interrogation signal into a zone to track the location and movement therein of inventory, merchandise, vehicles, animals, people and objects carrying passive (unpowered) transponder tags (12) adapted to receive the interrogation signal, process the signal in an encoded surface acoustic wave device (15) having a predetermined pattern of reflection groove or grating transducers (30-39, 40-72) and echo an encoded response signal to the transceiver.
315 Citations
11 Claims
- 1. A passive surface acoustic wave transponder device comprising electrical input and output connections, a substantially ominidirectional antenna generally coupled to said connections, a substrate having a surface of piezoelectric material, an electrode transducer contacting said surface of said substrate and connected to said input to launch said wave upon selective electromagnetic excitation of said antenna by a field broadcast from a transceiver remote from said antenna and device, and a plurality of encoded transducers disposed along the path of said wave for reflection of echoes thereof to said output without electrodes and conversion of said wave to a voltage at said encoded transducers.
Specification