Identification system using coded passive transponders
First Claim
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1. An identification system comprisingtransmitter means for transmitting an electromagnetic signal;
- a passive surface acoustic wave identifier adapted to produce a coded electronic reply in response to an electromagnetic signal, comprising a piezoelectric substrate, an input transducer carried by the piezoelectric substrate, a plurality of output transducers carried by the substrate and spaced from said input transducer at preselected intervals, and programming means for programming said output transducers to emit an electronic reply having a preselected sequential time order in response to a surface acoustic wave propogated by said input transducer, said programming means comprising pad means overlying said substrate in a zone intermediate said input transducer and an output transducer, whereby pressure applied to said substrate through said pad means renders said substrate non-conductive to a surface acoustic wave in said zone, thereby rendering any output transducer spaced distally of said pad means unresponsive to a surface acoustic wave propagated by said input transducer, and producing a preselectable variation in the coded electronic reply of said output transducers responsive to an electromagnetic signal;
receiver means for receiving said coded electronic reply; and
decoder means for matching the coded electronic reply of said identifier with stored coded pulse patterns.
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Abstract
An identification system including a transmitter, a receiver, a decoding subsystem, and a passive transponder identifier. One passive transponder identifier of the invention is a surface acoustic wave device provided with pad means for applying and removing pressure on a substrate of the device at preselected locations. A second identifier of the invention is a microacoustic shear bulk wave device. The passive transponder identifiers are programmed to produce a characteristic coded electronic reply in response to an electromagnetic signal interrogation.
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Citations
13 Claims
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1. An identification system comprising
transmitter means for transmitting an electromagnetic signal; -
a passive surface acoustic wave identifier adapted to produce a coded electronic reply in response to an electromagnetic signal, comprising a piezoelectric substrate, an input transducer carried by the piezoelectric substrate, a plurality of output transducers carried by the substrate and spaced from said input transducer at preselected intervals, and programming means for programming said output transducers to emit an electronic reply having a preselected sequential time order in response to a surface acoustic wave propogated by said input transducer, said programming means comprising pad means overlying said substrate in a zone intermediate said input transducer and an output transducer, whereby pressure applied to said substrate through said pad means renders said substrate non-conductive to a surface acoustic wave in said zone, thereby rendering any output transducer spaced distally of said pad means unresponsive to a surface acoustic wave propagated by said input transducer, and producing a preselectable variation in the coded electronic reply of said output transducers responsive to an electromagnetic signal; receiver means for receiving said coded electronic reply; and decoder means for matching the coded electronic reply of said identifier with stored coded pulse patterns.
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2. An identification system comprising
transmitter means for transmitting an electromagnetic signal; -
a passive microacoustic shear bulk wave identifier adapted to produce a coded electronic reply in response to an electromagnetic signal, said identifier comprising a substrate having a principal surface and a polished second surface opposed to said principal surface;
an input transducer supported on the principal surface and comprising a plurality of electrodes, a piezoelectric layer adjacent said electrodes, and a conductive film adjacent said piezoelectric layer; and
a plurality of output transducers situated adjacent the substrate at preselected locations corresponding to a code, whereby said output transducers emit a coded electronic reply having a preselected sequential time order in response to a microacoustic shear bulk wave propagated by said input transducer;receiver means for receiving said coded electronic reply; and decoder means for matching the coded electronic reply of said identifier with stored coded pulse patterns. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A passive microacoustic shear bulk wave identifier adapted to produce a coded electronic reply in response to an electromagnetic signal, comprising
a substrate have a principal surface and a polished second surface opposed to said principal surface, an input transducer supported on the principal surface and comprising a plurality of electrodes, a piezoelectric layer adjacent said electrodes, and a conductive film adjacent said piezoelectric layer, and a plurality of output transducers situated adjacent the substrate at preselected locations corresponding to a code, whereby said output transducers emit a coded electronic reply having a preselected sequential time order in response to a microacoustic shear bulk wave propagated by said input transducer.
Specification