Temperature measuring device

• US 20040076215A1
• Filed: 08/15/2003
• Published: 04/22/2004
• Est. Priority Date: 02/16/2001
• Status: Active Grant

• Current Assignee: Per Lennart Baumbach
• Original Assignee: Per Lennart Baumbach
• Inventors: Baumbach, Per Lennart
• Granted Patent: US 6,827,487 B2
• Time in Patent Office: Days
• US Class Current: 374/29
• 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 which is at a lower temperature, said device comprising:

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

a heater positioned to heat 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 heater 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 which is 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 heater so as to raise 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 heater 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 any one of the preceding claims, further comprising a user-operated control connected to activate said heater to preheat the heat shield.

6. A temperature measuring device as claimed in either one of claims 1 or 5, wherein said heater or cooler is a Peltier effect heat pump.

7. A temperature measuring device as claimed in any one of the preceding claims, wherein the specific thermal conductivity between the heater or cooler 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.

8. A temperature measuring device as claimed in claim 7, wherein the specific thermal conductivity between the heater or cooler 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.

9. A temperature measuring device as claimed in any one of the preceding claims, wherein the heat conductivity of said heat-conducting portion of the heat shield is at least 20 W/mK.

10. A temperature measuring device as claimed in any one of the preceding claims, wherein said heat-conducting portion of the heat shield is constructed from heat-conducting metal.

11. A temperature measuring device as claimed in claim 10, wherein said heat-conducting metal is copper, brass or stainless steel.

12. A temperature measuring device as claimed in any one of claims 1 to 9, wherein said heat-conducting portion of the heat shield is constructed from heat-conducting ceramic material.

13. A temperature measuring device as claimed in any one of claims 1 to 9, wherein said heat-conducting portion of the heat shield is constructed from copper and heat-conducting ceramic material.

14. A temperature measuring device as claimed in either one of claims 12 or 13, wherein said heat-conducting ceramic material is alumina, beryllia or aluminium nitride.

15. A temperature measuring device as claimed in any one of the preceding claims, wherein the conductivity of said heat-insulating inner portion is 0.2 W/mK or less.

16. A temperature measuring device as claimed in any one of the preceding claims, wherein said heat-insulating inner portion consists of a solid material formed by chemical or physical change of a liquid material introduced to the device.

17. A temperature measuring device as claimed in claim 15, wherein said heat-insulating solid material is epoxy or polyurethane resin or silicone rubber.

18. A temperature measuring device as claimed in any one of the preceding claims, 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.

19. A temperature measuring device as claimed in any one of claims 12 to 14, wherein said heater and/or temperature sensor comprises platinum, nickel or gold components applied directly onto said ceramic heat shield by thin-film metallisation techniques.

20. A temperature measuring device as claimed in any one of claims 12 to 14, wherein said heater and/or temperature sensor comprises platinum, gold or other metal layers or alloys or oxides thereof applied directly onto said ceramic heat shield by printing and firing of thick-film inks.

21. A temperature measuring device as claimed in any one of claims 12 to 14, wherein said first electronic control circuit comprises components applied to said ceramic heat shield by thick or thin film technologies.

22. A temperature measuring device as claimed in any one of the preceding claims, wherein the heat producing or removing parts of said first electronic control circuit are bonded directly onto said outer portion of the heat shield.

23. A temperature measuring device as claimed in any one of the preceding claims, wherein said first and second temperature sensors are each independently thermistors, thermocouples, transistors, temperature measuring ICs, or platinum film or wire resistance devices.

24. A temperature measuring device as claimed in any one of the preceding claims, wherein the device is powered by one or more batteries.

25. An assembly comprising a temperature measuring device as claimed in any one of the preceding claims and an ocular reaction light source.

26. An assembly as claimed in claim 25, further comprising a reflective pulse oximeter.

27. An assembly as claimed in either one of claims 25 or 26, further comprising a timer which produces an audible signal at the end of a specified period.

28. An assembly comprising a temperature measuring device as claimed in any one of claims 1 to 24 and a stethoscope for detecting heart rate.

29. A pen-like casing containing a temperature measuring device as claimed in any one of claims 1 to 24, or an assembly as claimed in any one of claims 25 to 28.

30. A pager-like casing containing a temperature measuring device as claimed in any one of claims 1 to 24, or an assembly as claimed in any one of claims 25 to 28.

5. A temperature measuring device for measuring the temperature within a body from a surface of the body which is at a higher temperature, 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 cooler positioned to cool the outer portion of said heat shield to the temperature of the surface of the body so as to annul heat flow to a measurement location within the area said surface to which the heat shield is applied, said cooler 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 which is 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 cooler so as to lower 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.