Ambient and perfusion normalized temperature detector

• US 6,056,435 A
• Filed: 06/24/1997
• Issued: 05/02/2000
• Est. Priority Date: 06/24/1997
• Status: Expired due to Term

• Current Assignee: Exergen Corporation
• Original Assignee: Exergen Corporation
• Inventors: Pompei, Francesco
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): PRUCHNIC, STANLEY J
• Application Number:
  US08/881,891
• Time in Patent Office: 1,043 Days
• Field of Search: 374/133, 600/549, 600/474, 702/131
• US Class Current: 374/133
• CPC Class Codes: G01J 5/0022 for sensing the radiation of moving bodies
• CPC Class Codes: G01J 5/0025 Living bodies ear thermometers G01J5/0011; detecting, measuring or recording for diagnostic purposes A61B5/00
• CPC Class Codes: G01J 5/02 Constructional details
• CPC Class Codes: G01J 5/025 Interfacing a pyrometer to an external device or network; User interface
• CPC Class Codes: G01J 5/026 Control of working procedures of a pyrometer, other than calibration; Bandwidth calculation; Gain control
• CPC Class Codes: G01J 5/0265 Handheld, portable ear thermometers G01J5/049
• CPC Class Codes: G01J 5/04 Casings
• CPC Class Codes: G01J 5/049 Casings for tympanic thermometers
• CPC Class Codes: G01J 5/06 Arrangements for eliminating effects of disturbing radiation; Arrangements for compensating changes in sensitivity for adjusting of solid angle of collected radiation G01J5/07; means for wavelength selection G01J5/0801
• CPC Class Codes: G01J 5/064 Ambient temperature sensor; Housing temperature sensor; Constructional details thereof
• CPC Class Codes: G01J 5/16 Arrangements with respect to the cold junction; Compensating influence of ambient temperature or other variables

Abstract

A body temperature detector is particularly suited to axillary temperature measurements of adults. The radiation sensor views a target surface area of the body and electronics compute an internal temperature of the body as a function of ambient temperature and sensed surface temperature. The function includes a weighted difference of surface temperature and ambient temperature, the weighting being varied with target temperature to account for varying perfusion rate. Preferably, the coefficient varies from a normal of about 0.13 through a range to include 0.09. The ambient temperature used in the function is assumed at about 80° F. but modified with detector temperature weighted by 20%.

Claims

1. A body temperature detector comprising:

a radiation sensor which views a target surface area of a body; and

electronics which compute an internal temperature of the body as a function of an ambient temperature and a sensed surface temperature, the function including a weighted difference of the sensed surface temperature and the ambient temperature, the weighted difference including a weighting factor which varies with the sensed surface temperature.

2. A temperature detector as claimed in claim 1 wherein the weighting factor is an approximation of h/pc where h is a heat transfer coefficient between the target surface and ambient, p is perfusion rate and c is blood specific heat.

3. A temperature detector as claimed in claim 2 wherein the approximation of h/pc is about 0.13.

4. A temperature detector as claimed in claim 3 wherein the approximation of h/pc varies over a range of at least 0.09 to 0.13.

5. A temperature detector as claimed in claim 2 wherein the approximation of h/pc varies over a range of at least 20% of 0.13.

6. A temperature detector as claimed in claim 2 wherein the slop of h/pc with respect to the sensed surface temperature is at least 0.01/°

F.

7. A temperature detector as claimed in claim 6 wherein the slope is about 0.02/°

F. at about a sensed surface temperature of 97°

.

8. A temperature detector as claimed in claim 1 wherein the ambient temperature included in the function is an assumed ambient temperature.

9. A temperature detector as claimed in claim 8 wherein the assumed ambient temperature is modified as a function of a sensed detector temperature, a change in the assumed ambient temperature relative to a change in the second detector temperature being significantly less than 1.

10. A temperature detector as claimed in claim 9 wherein the change in the assumed ambient temperature relative to the change in the sensed detector temperature is less than 0.5.

11. A temperature detector as claimed in claim 8 wherein the assumed ambient temperature is approximately 80°

F.

12. A temperature detector as claimed in claim 11 which provides accuracy over a range of interest of about 90°

to 105°

F.

13. A temperature detector as claimed in claim 1 which provides accuracy over a range of interest of about 90°

to 105°

F.

14. A body temperature detector comprising:

a radiation sensor which views a target surface area of a body; and

electronics which compute an internal temperature of the body as a function of an ambient temperature and a sensed surface temperature, including a weighted difference of the sensed surface temperature and the ambient temperature, the weighted difference including a weighting factor of about 0.13.

15. A temperature detector as claimed in claim 14 which provides accuracy over a range of interest of about 90°

to 105°

F.

16. A body temperature detector comprising:

a radiation sensor which views a target surface area of a body; and

electronics which compute an internal temperature of the body as a function of an ambient temperature and a sensed surface temperature, wherein the ambient temperature within the function is an assumed ambient temperature.

17. A temperature detector as claimed in claim 16 wherein the assumed ambient temperature is modified as a function of a sensed detector temperature, a change in the assumed ambient temperature relative to change in the sensed detector temperature being significantly less than 1.

18. A temperature detector as claimed in claim 17 wherein the change in the assumed ambient temperature relative to change in the sensed detector temperature is less than 0.5.

19. A temperature detector as claimed in claim 18 wherein the assumed ambient temperature is approximately 80°

F.

20. A temperature detector as claimed in claim 19 which provides accuracy over a range of interest of about 90°

to 105°

F.

21. A temperature detector as claimed in claim 17 wherein the change in the assumed ambient temperature relative to change in the sensed detector temperature is approximately 0.2.

22. A temperature detector as claimed in claim 21 wherein the assumed ambient temperature is approximately 80°

F.

23. A temperature detector as claimed in claim 16 wherein the assumed ambient temperature is fixed.

24. A temperature detector as claimed in claim 23 wherein the assumed ambient temperature is approximately 80°

.

35. A method as claimed in claim 24 wherein the ambient temperature included in the function is an assumed temperature of approximately 80°

F.

25. A body temperature detector comprising:

a radiation sensor which views a target surface area of a body; and

electronics which compute an internal temperature of the body as a function of ambient temperature and a sensed surface temperature, the function including a weighted difference of the sensed surface temperature and the ambient temperature, the weighted difference including a weighting factor which is an approximation of h/pc where h is a heat transfer coefficient between the target surface and ambient, p is perfusion rate and c is blood specific heat and h/pc varies over a range of at least 0.09 to 0.13 with the sensed surface temperature, and the ambient temperature being an assumed ambient temperature modified as a function of a sensed detector temperature, a change in the assumed ambient temperature relative to change in the sensed detector temperature being less than 0.5.

26. A temperature detector as claimed in claim 25 wherein the assumed ambient temperature is approximately 80°

F. and the change in the assumed ambient temperature relative to change in the sensed detector temperature is approximately 0.2.

27. A temperature detector as claimed in claim 26 which provides accuracy over a range of interest of about 90°

to 105°

F.

28. A temperature detector as claimed in claim 25 which provides accuracy over a range of interest of about 90°

to 105°

F.

29. A method of detecting body temperature comprising:

detecting radiation from a target surface area of a body;

computing an internal temperature of the body as a function of an ambient temperature and a sensed surface temperature, the function including a weighted difference of the sensed surface temperature and the ambient temperature, the weighted difference including a weighting factor which varies with the sensed surface temperature; and

providing a display of the internal temperature.

30. A method as claimed in claim 29 which provides accuracy over a range of interest of about 90°

to 105°

F.

31. A method as claimed in claim 30 wherein the ambient temperature included in the function is an assumed temperature of approximately 80°

F.

32. A method of detecting body temperature comprising:

detecting heat flux from a target surface area of a body;

computing an internal temperature of the body as a function of an ambient temperature and a sensed surface temperature, the ambient temperature within the function being an assumed ambient temperature; and

providing a display of the internal temperature.

33. A method as claimed in claim 32 which provides accuracy over a range of interest of about 90°

to 105°

F.

34. A method as claimed in claim 33 wherein the ambient temperature included in the function is an assumed temperature of approximately 80°

F.