Temperature measuring device

• US 6,827,487 B2
• Filed: 08/15/2003
• Issued: 12/07/2004
• Est. Priority Date: 02/16/2001
• Status: Active Grant

• Current Assignee: Per Lennart Baumbach
• Original Assignee: Per Lennart Baumbach
• Inventors: Baumbach, Per Lennart
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): PRUCHNIC, STANLEY J
• Application Number:
  US10/468,133
• Publication Number:
  US 20040076215A1
• Time in Patent Office: 480 Days
• Field of Search: 374/30, 374/43, 374/44, 374/163, 374/164, 374/178, 374/179, 374/183, 600/549, 600/528, 600/586, 600/398-405, 600/323
• US Class Current: 374/164
• CPC Class Codes: G01K 1/16 Special arrangements for conducting heat from the object to the sensitive element
• CPC Class Codes: G01K 1/165 for application in zero heat flux sensors
• CPC Class Codes: G01K 1/18 for reducing thermal inertia
• CPC Class Codes: G01K 7/42 Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature

Abstract

A device for measuring the temperature within a body from a body surface at a different temperature, comprising: a heat shield for application to the body surface, comprising an outer heat-conducting portion (52), and an inner heat-insulating portion (50); a heater or cooler (41) to heat or cool the outer portion (52) of said heat shield to the temperature of the body surface; a first temperature sensor (37) positioned on a surface of the inner heat-insulating portion (50) of the heat shield which is applied to the body surface; a second temperature sensor (38) positioned to measure the temperature of the outer portion (52) of the heat shield; a heater or cooler control circuit to heat or cool the outer portion (52) of the heat shield towards the temperature measured by the first the first temperature sensor (37); and a second control circuit to forecast the first temperature sensor (37) equilibrium temperature.

Claims

1. A temperature measuring device for measuring the temperature within a body from a surface of the body, said device comprising:

a heat shield for application to the surface of the body, comprising an outer heat-conducting portion, and an inner heat-insulating portion, both said portions having a surface for contacting said surface of the body;

a temperature controlling element positioned to control the temperature of the outer portion of said heat shield to the temperature of the surface of the body so as to annul heat flow from a measurement location within the area of said surface to which the heat shield is applied, said temperature controlling element being close to said surface of the outer portion of the heat shield which is applied to the surface of the body compared with its distance from an opposite surface of the outer portion of the heat shield;

a first temperature sensor positioned on said surface of the inner heat-insulating portion of the heat shield for contacting the surface of the body to measure the temperature of said surface at said measurement location;

a second temperature sensor positioned to measure the temperature of said outer portion of the heat shield;

a first electronic control circuit serving to operate said temperature controlling element so as to change the temperature of said outer portion of the heat shield as measured by said second temperature sensor towards the temperature at said measurement location as measured by said first temperature sensor; and

a second electronic control circuit serving to extrapolate changing temperatures measured by said first temperature sensor to forecast what the temperature at said measurement location would be at thermal equilibrium.

2. A temperature measuring device as claimed in claim 1, wherein said temperature controlling element comprises an electrically resistive heating element in contact with said outer portion of the heat shield.

3. A temperature measuring device as claimed in claim 2, wherein said heating element is embedded in said outer portion of the heat shield.

4. A temperature measuring device as claimed in claim 1, further comprising a control connected to activate said temperature controlling element to control the temperature of the heat shield before making a temperature measurement.

5. A temperature measuring device as claimed in claim 1, wherein said temperature controlling element is a Peltier effect heat pump.

6. A temperature measuring device as claimed in claim 1, wherein the specific thermal conductivity between the temperature controlling element and the surface of the heat-conducting portion of the heat shield for application to the surface of the body is 2 W/cm²K or more.

7. A temperature measuring device as claimed in claim 6, wherein the specific thermal conductivity between the temperature controlling element and the surface of the heat-conducting portion of the heat shield for application to the surface of the body is 6.5 W/cm²K or more.

8. A temperature measuring device as claimed in claim 1, wherein the heat conductivity of said heat-conducting portion of the heat shield is at least 20 W/mK.

9. A temperature measuring device as claimed in claim 1, wherein said heat-conducting portion of the heat shield is constructed from heat-conducting metal.

10. A temperature measuring device as claimed in claim 9, wherein said heat-conducting metal is one of copper, brass and stainless steel.

11. A temperature measuring device as claimed in claim 1, wherein said heat-conducting portion of the heat shield is constructed from heat-conducting ceramic material.

12. A temperature measuring device as claimed in claim 11, wherein said heat-conducting ceramic material comprises at least one of alumina, beryllia and aluminium nitride.

13. A temperature measuring device as claimed in claim 11, wherein at least one of the temperature controlling element and the first temperature sensor comprises components of at least one of platinum, nickel and gold applied directly onto said ceramic heat shield by thin-film metallisation techniques.

14. A temperature measuring device as claimed in claim 11, wherein at least one of said temperature controlling element and said first temperature sensor comprises a layer of at least one of a metal, metal, a metal alloy and a metal oxide applied directly onto said ceramic heat shield.

15. A temperature measuring device as claimed in claim 14, wherein the layer comprises at least one of platinum and gold.

16. A temperature measuring device as claimed in claim 11, wherein said first electronic control circuit comprises components applied to said ceramic heat shield by one of thick and thin film technologies.

17. A temperature measuring device as claimed in claim 1, wherein said heat-conducting portion of the heat shield is constructed from copper and heat-conducting ceramic material.

18. A temperature measuring device as claimed in claim 1, wherein the conductivity of said heat-insulating inner portion is 0.2 W/mK or less.

19. A temperature measuring device as claimed in claim 18, wherein said heat-insulating solid material comprises at least one of epoxy, polyurethane resin and silicone rubber.

20. A temperature measuring device as claimed in claim 1, wherein said heat-insulating inner portion comprises a solid material formed by chemical or physical change of a liquid material introduced to the device.

21. A temperature measuring device as claimed in claim 1, wherein said heat-conducting portion of the heat shield comprises a heat-conducting cup, having an open end for application to the surface of the body, and said heat-insulating inner portion of the heat-shield comprises a heat-insulating material filling said heat-conducting cup.

22. A temperature measuring device as claimed in claim 1, wherein said first electronic control circuit comprises heat producing parts bonded directly onto said outer portion of the heat shield.

23. A temperature measuring device as claimed in claim 1, wherein said first and second temperature sensors are each one of a thermistor, a thermocouple, a transistor, a temperature measuring IC, a platinum film and a wire resistance device.

24. A temperature measuring device as claimed in claim 1, comprising one or more batteries for providing electrical power to electrically-based elements in the device.

25. A temperature measuring device as claimed in claim 1, wherein said temperature controlling element includes a heater.

26. A temperature measuring device as claimed in claim 1, wherein said temperature controlling element includes a cooler.

27. A temperature measuring device as claimed in claim 1, further comprising a housing containing at least said heat shield, said temperature controlling element and said first and second temperature sensors.

28. A temperature measuring device as claimed in claim 27, further comprising an ocular reaction light source disposed within said housing.

29. A temperature measuring device as claimed in claim 27, further comprising a reflective pulse oximeter disposed within said housing.

30. A temperature measuring device as claimed in claim 27, further comprising a timer disposed within said housing, said timer producing an audible signal at the end of a specified period.

31. A temperature measuring device as claimed in claim 27, further comprising an acoustic sensor disposed within said housing for detecting heart rate.

32. A temperature measuring device as claimed in claim 27, wherein said housing is elongated in one dimension, the first temperature sensor being located at one end of the elongated housing.

33. A temperature measuring device as claimed in claim 27, wherein said housing has is substantially smaller in one dimension than the other two dimensions, the first temperature sensor being located on a face of the housing.