Ear thermometer with improved temperature coefficient and method of calibration thereof

• US 20040057494A1
• Filed: 09/19/2002
• Published: 03/25/2004
• Est. Priority Date: 09/19/2002
• Status: Abandoned Application

• Current Assignee: Radiant Innovation Inc.
• Original Assignee: Radiant Innovation Inc.
• Inventors: Chang, Yung-Chang, Liao, Chien-Chang, Weng, Nien-Yu, Tsao, Simon
• Application Number:
  US10/251,600
• Publication Number:
  US 20040057494A1
• Time in Patent Office: Days
• US Class Current: 374/121
• CPC Class Codes: G01J 5/04 Casings
• CPC Class Codes: G01J 5/049 Casings for tympanic thermometers
• CPC Class Codes: G01J 5/061 by controlling the temperature of the apparatus or parts thereof, e.g. using cooling means or thermostats
• CPC Class Codes: G01J 5/064 Ambient temperature sensor; Housing temperature sensor; Constructional details thereof
• CPC Class Codes: G01J 5/10 using electric radiation detectors
• CPC Class Codes: G01J 5/70 Passive compensation of pyrometer measurements, e.g. using ambient temperature sensing or sensing of temperature within housing
• CPC Class Codes: G01J 5/80 Calibration using comparison with reference sources G01J5/52

Abstract

An ear thermometer is tested at the time of manufacturing calibration for determining a temperature coefficient to be stored in information storing means. Based on the temperature coefficient, signal processing means compensates an undesirable temperature deviation caused by a change of an ambient temperature upon temperature taking, thereby enhancing the accuracy of the ear thermometer. Also, a method is provided for calibrating the ear thermometer by determining the temperature coefficient without increasing additional cost and calibration procedures.

Claims

1. An ear thermometer with an improved temperature coefficient comprising:

infrared radiation sensor means for sensing an infrared radiation from a target and generating a first electronic signal;

temperature sensor means for sensing a temperature of the infrared radiation sensor means so as to use the temperature as an ambient temperature and generating a second electronic signal;

analog/digital signal converting means connected to the infrared radiation sensor means and the temperature sensor means for converting the first electronic signal and the second electronic signal into digital signals, respectively;

information storing means for storing a temperature coefficient; and

signal processing means for processing the first electronic signal generated by the infrared radiation sensor means and the second electronic signal generated by the temperature sensor means and compensating by using the temperature coefficient stored in the information storing means so as to calculate an amount of the infrared radiation from the target, and to obtain a target temperature according to the amount of the infrared radiation.

2. The ear thermometer as claimed in claim 1, further comprising:

signal amplifying means coupled between the infrared radiation sensor means and the analog/digital signal converting means for amplifying the first electronic signal generated by the infrared radiation sensor means and then entering into the analog/digital signal converting means.

3. The ear thermometer as claimed in claim 1, further comprising:

display means coupled to the signal processing means for displaying the target temperature calculated by the signal processing means.

4. The ear thermometer as claimed in claim 1, wherein the information storing means is an electrically non-volatile memory.

5. The ear thermometer as claimed in claim 1, wherein the signal processing means is a central processing unit.

6. The ear thermometer as claimed in claim 1, wherein the target temperature is calculated by the following equation:

T_ear=(Q_dn×

K_t0(1+TCO×

(T_amb−

T_ambBase))+T_amb⁴)^(1/4)

where T_ear is the target temperature, Q_dn is an output of the infrared radiation received by the infrared radiation sensor means, T_amb is the ambient temperature, T_ambBase is a constant calibration ambient temperature of the ear thermometer when a manufacturing calibration is executed, K_t0 is a constant calculated from the constant calibration ambient temperature, and TCO is the temperature coefficient stored in the information storing means.

7. A method of calibrating the ear thermometer with an improved temperature coefficient comprising:

determining output voltages of temperature sensor means at a first calibration ambient temperature and a second calibration ambient temperature, respectively, thereby calibrating the temperature sensor means for enhancing accuracy thereof and calculating a temperature coefficient at the same time, and

determining a responsive output of the temperature sensor means at a given target temperature and a given constant calibration ambient temperature thereby calculating a calibration constant according to the responsive output.

8. The method as claimed in claim 7, wherein the temperature coefficient is calculated by the following equation:

TCO=(V_ref1−

V_ref2)/V_ref1/(T_amb1−

T_amb2)

where TCO is the temperature coefficient, T_amb1 is the first calibration ambient temperature, T_amb2 is the second calibration ambient temperature, and V_ref1 and V_ref2 are the output voltages determined from the first calibration ambient temperature and the second calibration ambient temperature, respectively.

9. The method as claimed in claim 7, wherein the calibration constant is calculated by the following equation:

K_t0=(T_ear⁴−

T_ambBase⁴)/Q_dn

where K_t0 the calibration constant, T_ear is the given target temperature, T_ambBase is the given constant calibration ambient temperature, and Q_dn is the responsive output.

10. The method as claimed in claim 7, wherein the first calibration ambient temperature is 15°

C.

11. The method as claimed in claim 7, wherein the second calibration ambient temperature is 30°

C.

12. The method as claimed in claim 7, wherein the given target temperature is 38°

C.

13. The method as claimed in claim 7, wherein the given constant calibration ambient temperature is 25°

C.

14. A method of calibrating the ear thermometer with an improved temperature coefficient comprising:

inputting a stable and precise reference voltage to analog/digital converting means of the ear thermometer and determining outputs thereof at a given first calibration ambient temperature and a given second calibration ambient temperature, respectively, thereby calibrating temperature sensor means and calculating a temperature coefficient, and

determining a responsive output of the temperature sensor means at a given target temperature and a given constant calibration ambient temperature thereby calculating a calibration constant according to the responsive output.

15. The method as claimed in claim 14, wherein the temperature coefficient is calculated by applying the following equation:

TCO=(Q_dn1−

Q_dn2)/Q_dn1/(T_amb1−

T_amb2)

where TCO is the temperature coefficient, T_amb1 is the first calibration ambient temperature, T_amb2 is the second calibration ambient temperature, and Q_dn1 and Q_dn2 are the output determined from the first calibration ambient temperature and the second calibration ambient temperature, respectively.

16. The method as claimed in claim 14, wherein the calibration constant is calculated by applying the following equations:

K_t0=(T_ear⁴−

T_ambBase⁴)/Q_dn

where K_t0 is the calibration constant, T_ear is the given target temperature, T_ambBase is the given constant calibration ambient temperature, and Q_dn is the responsive output.

17. The method as claimed in claim 14, wherein the first calibration ambient temperature is 15°

C.

18. The method as claimed in claim 14, wherein the secondcalibration ambient temperature is 30°

C.

19. The method as claimed in claim 14, wherein the given target temperature is 38°

C.

20. The method as claimed in claim 14, wherein the given constant calibration ambient temperature is 25°

C.