Method of calibrating a radiation thermometer

• US 6,283,629 B1
• Filed: 04/04/2000
• Issued: 09/04/2001
• Est. Priority Date: 04/02/1996
• Status: Expired due to Fees

• Current Assignee: Braun GmbH (The Procter & Gamble Company)
• Original Assignee: Braun GmbH (The Procter & Gamble Company)
• Inventors: Kraus, Bernhard, Kaiser, Manfred, Beerwerth, Frank, Heubach, Klaus
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): PRUCHNIC, STANLEY J
• Application Number:
  US09/542,214
• Time in Patent Office: 518 Days
• Field of Search: 374/2, 374/1, 374/133, 250/252.1
• US Class Current: 374/2
• CPC Class Codes: G01J 5/064 Ambient temperature sensor; Housing temperature sensor; Constructional details thereof
• CPC Class Codes: G01J 5/53 Reference sources, e.g. standard lamps; Black bodies
• CPC Class Codes: G01J 5/80 Calibration using comparison with reference sources G01J5/52

Abstract

A method of calibrating a radiation thermometer including a radiation sensor that is characterized by a sensitivity (S) and a temperature-responsive resistor that serves as an ambient temperature sensor, the temperature-responsive resistor having at a specified reference temperature a reference resistance (R₀). The method includes the steps of using a first radiation standard having a known temperature T_S(1); while the ambient temperature sensor is at a first ambient temperature T_U(1), using the radiation thermometer to read the temperature of the first radiation standard; while using the radiation thermometer to read the temperature of the first radiation standard, measuring a first output signal U(1) of the radiation sensor; using a second radiation standard having a known temperature T_S(2); while the ambient temperature sensor is at said first ambient temperature T_U(1), using the radiation thermometer to read the temperature of the second radiation standard; while using the radiation thermometer to read the temperature of the second radiation standard, measuring a second output signal U(2) of the radiation sensor; and calibrating the radiation sensor and the ambient temperature sensor by using T_S(1), T_S(2) and the values obtained for U(1) and U(2) and without using any value for T_U(1) that is derived from measuring an output of the ambient sensor, wherein the step of calibrating involves calculating at least one of the reference resistance (R₀) of the ambient temperature sensor, the ambient temperature (T_u), and the sensitivity (S) of the radiation sensor.

Claims

1. A method of calibrating a radiation thermometer including a radiation sensor that is characterized by a sensitivity (S) and an ambient temperature sensor, said method comprising:

using a first radiation standard having a known temperature T_S(1);

while the ambient temperature sensor is at a first ambient temperature T_U, using the radiation thermometer to read the temperature of the first radiation standard;

while using the radiation thermometer to read the temperature of the first radiation standard, measuring a first output signal U(1) of the radiation sensor;

using a second radiation standard having a known temperature T_S(2);

while the ambient temperature sensor is at said first ambient temperature T_U, using the radiation thermometer to read the temperature of the second radiation standard;

while using the radiation thermometer to read the temperature of the second radiation standard, measuring a second output signal U(2) of the radiation sensor; and

calibrating the radiation sensor and the ambient temperature sensor by using T_S(1), T_S(2) and the values obtained for U(1) and U(2) and without using any value for T_U that is derived from measuring an output of the ambient temperature sensor, wherein said step of calibrating involves calculating at least one of the first ambient temperature T_U, and the sensitivity (S) of the radiation sensor.

2. The method of claim 1 wherein the ambient temperature sensor is a temperature-responsive resistor having at a specified reference temperature a reference resistance R₀, said method further comprising measuring the resistance R(T_u) of the ambient temperature sensor at said first ambient temperature T_U and calculating the reference resistance R₀ of the ambient temperature sensor by using the calculated first ambient temperature T_U.

3. A method of calibrating a radiation thermometer including a radiation sensor and a temperature-responsive resistor that serves as an ambient temperature sensor, wherein the temperature-responsive resistor has at a specified temperature a reference resistance R₀ and a temperature dependence that is characterized by a linear temperature coefficient, said method comprising:

using a first radiation standard having a known temperature T_S(1);

while the ambient temperature sensor is at a first ambient temperature T_U, using the radiation thermometer to read the temperature of the first radiation standard;

while using the radiation thermometer to read the temperature of the first radiation standard, measuring a first output signal U(1) of the radiation sensor;

using a second radiation standard having a known temperature T_S(2);

while the ambient temperature sensor is at said first ambient temperature T_U, using the radiation thermometer to read the temperature of the second radiation standard;

while using the radiation thermometer to read the temperature of the second radiation standard, measuring a second output signal U(2) of the radiation sensor;

measuring a resistance R(T_U) of the ambient temperature sensor at said first ambient temperature T_U;

using a third radiation standard having a known temperature T_S(3);

while the ambient temperature sensor is at a second ambient temperature T_U′

, using the radiation thermometer to read the temperature of the third radiation standard;

while using the radiation thermometer to read the temperature of the third radiation standard, measuring a third output signal U(3) of the radiation sensor;

using a fourth radiation standard having a known temperature T_S(4);

while the ambient temperature sensor is at said second ambient temperature T_U′

, using the radiation thermometer to read the temperature of the fourth radiation standard;

while using the radiation thermometer to read the temperature of the fourth radiation standard, measuring a fourth output signal U(4) of the radiation sensor;

measuring a resistance R(T_U′

) of the ambient temperature sensor at said second ambient temperature T_U′

; and

calibrating the ambient temperature sensor by using T_S(1), T_S(2), T_S(3) and T_S(4) and the values obtained for U(1), U(2), U(3) and U(4) and without using any values for T_U and T_U′

that are derived from measuring an output of the ambient temperature sensor, and wherein the step of calibrating involves calculating the first and second ambient temperatures T_U and T_U′ and

calculating the reference resistance R₀ and the linear temperature coefficient of the temperature-responsive resistor by using the calculated first and second ambient temperatures T_U and T_U′

.

4. The method of claim 3, wherein the radiation sensor is characterized by a sensitivity (S), and wherein the step of calibrating involves calculating the sensitivity (S) of the radiation sensor by using one of a first group of values and a second group of values, said first group consisting of T_s(1), T_s(2), U(1), and U(2) and said second group consisting of T_S(3), T_S(4), U(3), and U(4).

5. The method of claims 3 or 4 further comprising using the first radiation standard as the third radiation standard so that T_S(3)=T_S(1) and using the second radiation standard as the fourth radiation standard so that T_S(4)=T_S(2).

6. A method of calibrating a radiation thermometer including a radiation sensor and a temperature-responsive resistor that serves as an ambient temperature sensor, wherein the temperature-responsive resistor has at a specified reference temperature a reference resistance R₀ and a temperature dependence that is characterized by a linear temperature coefficient and a quadratic temperature coefficient, said method comprising:

using a first radiation standard having a known temperature T_S(1);

while the ambient temperature sensor is at a first ambient temperature T_U, using the radiation thermometer to read the temperature of the first radiation standard;

while using the radiation thermometer to read the temperature of the first radiation standard, measuring a first output signal U(1) of the radiation sensor;

using a second radiation standard having a known temperature T_S(2);

while the ambient temperature sensor is at said first ambient temperature T_U, using the radiation thermometer to read the temperature of the second radiation standard;

while using the radiation thermometer to read the temperature of the second radiation standard, measuring a second output signal U(2) of the radiation sensor;

measuring a resistance R(T_U) of the ambient temperature sensor at said first ambient temperature T_U;

using a third radiation standard having a known temperature T_S(3);

while the ambient temperature sensor is at a second ambient temperature T_U′

, using the radiation thermometer to read the temperature of the third radiation standard;

while using the radiation thermometer to read the temperature of the third radiation standard, measuring a third output signal U(3) of the radiation sensor;

using a fourth radiation standard having a known temperature T_S(4);

while the ambient temperature sensor is at said second ambient temperature T_U′

, using the radiation thermometer to read the temperature of the fourth radiation standard; and

while using the radiation thermometer to read the temperature of the fourth radiation standard, measuring a fourth output signal U(4) of the radiation sensor;

measuring a resistance R(T_U′

) of the ambient temperature sensor at said second ambient temperature T_U′

;

using a fifth radiation standard having a known temperature T_S(5);

while the ambient temperature sensor is at a third ambient temperature T_U″

, using the radiation thermometer to read the temperature of the fifth radiation standard;

while using the radiation thermometer to read the temperature of the fifth radiation standard, measuring a fifth output signal U(5) of the radiation sensor;

using a sixth radiation standard having a known temperature T_S(6);

while the ambient temperature sensor is at said third ambient temperature T_U″

, using the radiation thermometer to read the temperature of the sixth radiation standard;

while using the radiation thermometer to read the temperature of the sixth radiation standard, measuring a sixth output signal U(6) of the radiation sensor;

measuring a resistance R(T_U″

) of the ambient temperature sensor at said third ambient temperature T_U″

; and

calibrating the ambient temperature sensor by using T_S(1), T_S(2), T_S(3), T_S(4), T_S(5) and T_S(6) and the values obtained for U(1), U(2), U(3), U(4), U(5) and U(6) and without using any values for T_U, T_U′

, and T_U″

that are derived from measuring an output of the ambient temperature sensor and wherein the step of calibrating involves calculating the first, second and third ambient temperatures, and calculating the reference resistance R₀ and the linear temperature coefficient and the quadratic temperature coefficient of the temperature-responsive resistor by using the calculated first, second and third ambient temperatures T_U, T_U′

, and T_U″

.

7. The method of claim 6, wherein the radiation sensor is characterized by a sensitivity (S), and wherein the step of calibrating involves calculating the sensitivity (S) of the radiation sensor by using one of first group of values, a second group of values, and a third group of values, said first group consisting of T_S(1), T_S(2), U(1), U(2), said second group consisting of T_S(3), T_S(4), U(3), and U(4), and said third group consisting of T_S(5), T_S(6), U(5), and U(6).

8. The method of claim 6 or 7 further comprising using the first radiation standard as the third radiation standard so that T_S(3)=T_S(1) and using the second radiation standard as the fourth radiation standard so that T_S(4)=T_S(2).

9. The method of claim 6 or 7 further comprising using the first radiation standard as the fifth radiation standard so that T_S (5)=T_S(1) and using the second radiation standard as the sixth radiation standard so that T_S(6)=T_S(2).

10. A method of calibrating a radiation thermometer including a radiation sensor and an ambient temperature sensor, wherein the ambient temperature sensor outputs at a specified reference temperature a reference output value R₀ and has a temperature dependence that is characterized by a linear temperature coefficient, said method comprising:

using a first radiation standard having a known temperature T_S(1);

while the ambient temperature sensor is at a first ambient temperature T_U, using the radiation thermometer to read the temperature of the first radiation standard;

while using the radiation thermometer to read the temperature of the first radiation standard, measuring a first output signal U(1) of the radiation sensor;

using a second radiation standard having a known temperature T_S(2);

while the ambient temperature sensor is at said first ambient temperature T_U, using the radiation thermometer to read the temperature of the second radiation standard;

while using the radiation thermometer to read the temperature of the second radiation standard, measuring a second output signal U(2) of the radiation sensor;

measuring the output value R(T_U) of the ambient temperature sensor at said first ambient temperature T_U;

using a third radiation standard having a known temperature T_S(3);

while the ambient temperature sensor is at a second ambient temperature T_U′

, using the radiation thermometer to read the temperature of the third radiation standard;

while using the radiation thermometer to read the temperature of the third radiation standard, measuring a third output signal U(3) of the radiation sensor;

using a fourth radiation standard having a known temperature T_S(4);

while the ambient temperature sensor is at said second ambient temperature T_U′

, using the radiation thermometer to read the temperature of the fourth radiation standard;

while using the radiation thermometer to read the temperature of the fourth radiation standard, measuring a fourth output signal U(4) of the radiation sensor;

measuring the output value R(T_U′

) of the ambient temperature sensor at said second ambient temperature T_U′

; and

calibrating the ambient temperature sensor by using T_S(1), T_S(2), T_S(3), T_S(4) and the values obtained for U(1), U(2), U(3) and U(4) and without using any values for T_U and T_U′

that are derived from measuring an output of the ambient temperature sensor, and wherein the step of calibrating involves calculating the first and second ambient temperatures T_U, T_U′ and

calculating the reference output value R₀ and the linear temperature coefficient of the ambient temperature sensor by using the calculated first and second ambient temperatures T_U, T_U′

.

11. The method of claim 10, wherein the radiation sensor is characterized by a sensitivity (S), and wherein the step of calibrating involves calculating the sensitivity (S) of the radiation sensor by using either T_S(1), T_S(2) and the values obtained for U(1) and U(2) or T_S(3), T_S(4) and the values obtained for U(3) and U(4).

12. The method of claim 10 or 11 further comprising using the first radiation standard as the third radiation standard so that T_S(3)=T_S(1) and using the second radiation standard as the fourth radiation standard so that T_S(4)=T_S(2).

13. A method of calibrating a radiation thermometer including a radiation sensor and an ambient temperature sensor, wherein the ambient temperature sensor outputs at a specified reference temperature a reference output value R₀ and has a temperature dependence that is characterized by a linear temperature coefficient and a quadratic temperature coefficient, said method comprising:

using a first radiation standard having a known temperature T_S(1);

while the ambient temperature sensor is at a first ambient temperature T_U, using the radiation thermometer to read the temperature of the first radiation standard;

while using the radiation thermometer to read the temperature of the first radiation standard, measuring a first output signal U(1) of the radiation sensor;

using a second radiation standard having a known temperature T_S(2);

while the ambient temperature sensor is at said first ambient temperature T_U, using the radiation thermometer to read the temperature of the second radiation standard;

while using the radiation thermometer to read the temperature of the second radiation standard, measuring a second output signal U(2) of the radiation sensor;

measuring the output value R(T_U) of the ambient temperature sensor at said first ambient temperature T_U;

using a third radiation standard having a known temperature T_S(3);

while the ambient temperature sensor is at a second ambient temperature T_U′

, using the radiation thermometer to read the temperature of the third radiation standard;

while using the radiation thermometer to read the temperature of the third radiation standard, measuring a third output signal U(3) of the radiation sensor;

using a fourth radiation standard having a known temperature T_S(4);

while the ambient temperature sensor is at said second ambient temperature T_U′

, using the radiation thermometer to read the temperature of the fourth radiation standard;

while using the radiation thermometer to read the temperature of the fourth radiation standard, measuring a fourth output signal U(4) of the radiation sensor;

measuring the output value R(T_U′

) of the ambient temperature sensor at said second ambient temperature T_U′

;

using a fifth radiation standard having a known temperature T_S(5);

while the ambient temperature sensor is at a third ambient temperature T_U″

, using the radiation thermometer to read the temperature of the fifth radiation standard;

while using the radiation thermometer to read the temperature of the fifth radiation standard, measuring a fifth output signal U(5) of the radiation sensor;

using a sixth radiation standard having a known temperature T_S(6);

while the ambient temperature sensor is at said third ambient temperature T_U″

, using the radiation thermometer to read the temperature of the sixth radiation standard;

while using the radiation thermometer to read the temperature of the sixth radiation standard, measuring a sixth output signal U(6) of the radiation sensor;

measuring the output value R(T_U″

) of the ambient temperature sensor at said third ambient temperature T_U″

; and

calibrating the ambient temperature sensor by using T_S(1), T_S(2), T_S(3), T_S(4), T_S(5), T_S(6) and the values obtained for U(1), U(2), U(3), U(4), U(5) and U(6) and without using any values for T_U, T_U′ and

T_U″

that are derived from measuring an output of the ambient temperature sensor and wherein the step of calibrating involves calculating the first, second and third ambient temperatures T_U, T_U′

, T_U″ and

calculating the reference output value R₀ and the linear temperature coefficient and the quadratic temperature coefficient of the ambient temperature sensor by using the calculated first, second and third ambient temperatures T_U, T_U′

, T_U″

.

14. The method of claim 13, wherein the radiation sensor is characterized by a sensitivity (S), and wherein the step of calibrating involves calculating the sensitivity (S) of the radiation sensor by using either T_S(1), T_S(2) and the values obtained for U(1) and U(2) or T_S(3), T_S(4) and the values obtained for U(3) and U(4) or T_S(5), T_S(6) and the values obtained for U(5) and U(6).

15. The method of claim 13 or 14 further comprising using the first radiation standard as the third radiation standard so that T_S(3)=T_S(1) and using the second radiation standard as the fourth radiation standard so that T_S(4)=T_S(2).

16. The method of claim 13 or 14 further comprising using the first radiation standard as the fifth radiation standard so that T_S(5)=T_S(1) and using the second radiation standard as the sixth radiation standard so that T_S(6)=T_S(2).