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Apparatus for remote temperature reading

  • US 4,399,441 A
  • Filed: 01/19/1981
  • Issued: 08/16/1983
  • Est. Priority Date: 01/25/1980
  • Status: Expired due to Fees
First Claim
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1. Apparatus for remote temperature reading comprising transmitter means for transmitting electro-magnetic signals, label means adapted for attachment to or implantation in an article or animal for receiving a signal transmitted from said transmitter means and for retransmitting a reply, and receiver means for receiving and processing the reply;

  • said label means including antenna means for receiving said transmitted signal, transducer means for converting said electromagnetic signal to a surface acoustic wave, a path on said label over which said surface acoustic wave travels, the time of travel of said surface acoustic wave over said path being a function of the temperature of the path, the same or further transducer means being arranged to convert said surface acoustic wave to a first electromagnetic signal after it has travelled over a first part of said path and to feed said signal to said antenna means for retransmission to said receiver means and thereafter to convert said surface acoustic wave to a second electromagnetic signal after it has travelled over a second part of said path and to feed said second electromagnetic signal to said antenna means for retransmission to said receiver means, said receiver means including circuitry for measuring the time interval between said first and second electromagnetic signals resulting from the passage of said surface acoustic wave over said path and for providing from said measured time interval an output indicative of the temperature of the environment of the label means.

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