# US 4,399,441 A · Apparatus for remote temperature reading > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,399,441 A - Document ID: US4399441A - Status: Granted - Kind: A - Application number: 06/226,518 - Filed: 1981-01-19 - Granted: 1983-08-16 - Earliest claimed: 1980-01-25 - Assignees: Unisearch Limited - Inventors: Richard Vaughan; Peter H. Cole - Web page: https://patentgrep.com/patent/US4399441A ## CPC - G06K 19/0675: {the resonating marks being of the surface acoustic wave [SAW] kind (SAW devices per se H03H9/64)} - B61L 25/045: {using reradiating tags} - G01K 1/024: for remote indication - G01K 11/24: of the velocity of propagation of sound - G01S 13/765: {with exchange of information between interrogator and responder} - A61K 38/00: Medicinal preparations containing peptides (peptides containing beta-lactam rings A61K31/00; cyclic dipeptides not having in their molecule any other peptide link than those which form their ring, e.g. piperazine-2,5-diones, A61K31/00; ergot alkaloids of the cyclic peptide type A61K31/48; containing macromolecular compounds having statistically distributed amino acid units A61K31/74; medicinal preparations containing antigens or antibodies A61K39/00; medicinal preparations characterised by the non-active ingredients, e.g. peptides as drug carriers, A61K47/00) - G06K: GRAPHICAL DATA READING (image or video recognition or understanding G06V); PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS - B61L: GUIDING RAILWAY TRAFFIC; ENSURING THE SAFETY OF RAILWAY TRAFFIC (brakes or auxiliary equipment B61H, B61K; point or crossing construction E01B) - G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00) - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D) ## Abstract An apparatus for remote temperature reading particularly for the reading of the temperature of an article or animal at a distance by means of an electromagnetically interrogatable label attached to or implanted in the article or animal the label being constructed to be capable of receiving an electromagnetic signal from a transmitter, converting the signal to a surface acoustic wave, passing the wave over a path on the label, reconverting the surface acoustic wave to an electromagnetic signal and retransmitting it to a receiver. The path of the surface acoustic wave is of a material such that the time of travel of the surface acoustic wave over the path is a function of the temperature of the path and thus of the label. The receiver is constructed to measure the time interval between electromagnetic signals produced by the passage of the surface acoustic wave past a transducer or transducers in the path and thereby provide an output indicative of the temperature of the environment of the label. It is preferred that the label includes a plurality of transducers at coded locations along the path arranged for retransmitting to the receiver a coded sequence of electromagnetic signals indicative of an article or animal to which the label is affixed or in which it is implanted in the manner described in U.S. Pat. No. 3,706,094. ## Claims ### Claim 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. ### Claim 2 (depends on 1) Apparatus as claimed in claim 1 wherein said label means includes a plurality of transducer means at coded locations along said path arranged for retransmitting to said receiver means a coded sequence of electromagnetic signals indicative of an article or an animal to which said label is affixed or in which it is implanted. ### Claim 3 (depends on 1, 2) Apparatus as claimed in claim 1 or 2 wherein the transmitter means is constructed and arranged to transmit electromagnetic signals in the form of pulses of radio frequency energy and the receiver is constructed and arranged to receive reply signals in this form and to measure the time interval between said first and second electromagnetic signals by measurement of the change in phase between said signals resulting from the passage of said surface acoustic wave over said path. ### Claim 4 (depends on 1) Apparatus as claimed in claim 1 wherein the said path is closed on itself and a single transducer means is included in said path. ### Claim 5 (depends on 1) Apparatus as claimed in claim 1 wherein a single transducer means is provided in said path having reflector means provided on each side of it, said reflector means being at different distances from the transducer means, said path extending between said reflector means.