Infrared ear thermometer

• US 20020181540A1
• Filed: 07/18/2002
• Published: 12/05/2002
• Est. Priority Date: 09/15/1998
• Status: Active Grant

• Current Assignee: Jonathan Gerlitz
• Original Assignee: Jonathan Gerlitz
• Inventors: Gerlitz, Jonathan
• Granted Patent: US 6,811,306 B2
• Time in Patent Office: Days
• US Class Current: 374/121
• CPC Class Codes: G01J 5/02 Constructional details
• CPC Class Codes: G01J 5/0275 Control or determination of height or distance or angle information for sensors or receivers
• CPC Class Codes: G01J 5/028 using a charging unit or battery
• 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 5/061 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 5/16 Arrangements with respect to the cold junction; Compensating influence of ambient temperature or other variables
• CPC Class Codes: G01J 5/70 Passive compensation of pyrometer measurements, e.g. using ambient temperature sensing or sensing of temperature within housing

Abstract

An infrared ear thermometer includes a detector head housing, a heat sink, a recess formed in the heat sink, a thermopile sensor mounted within the recess, a thermistor, and temperature determination circuitry. The recess defines an aperture that limits the field of view of the thermopile sensor. The thermal capacities and conductivities of the heat sink and the thermopile sensor are selected so that the output signal of the thermopile sensor stabilizes during a temperature measurement. A method of determining temperature using the ear thermometer takes successive measurements, stores the measurements in a moving time window, averages the measurements in the moving window, determines whether the average has stabilized, and outputs an average temperature. A method of calculating a subject'"'"'s temperature determines the temperature of a cold junction of the thermopile, looks up a bias and slope of the thermopile based upon the temperature of the cold junction, measures the output of the thermopile, and calculates the subject'"'"'s temperature based upon a linear relationship between the output and the subject'"'"'s temperature. The linear relationship is defined by the bias and the slope.

Claims

1. A method for determining the temperature of a subject, the method comprising:

taking successive temperature measurements of the subject using an infrared thermometer;

storing a plurality of most recent temperature measurements in a moving time window;

successively calculating an average of up to all of the plurality of stored measurements;

calculating the difference between successive averages;

determining whether the difference is less than a predetermined value; and

outputting a calculated average temperature.

2. A method for calculating a subject'"'"'s temperature based upon output values from a thermopile and a thermistor of an infrared thermometer, wherein the thermistor is in thermal communication with a cold junction of the thermopile, and wherein the hot junction is in infrared communication with an object to be measured, the method comprising:

determining the temperature of the cold junction with the thermistor;

looking up a bias and a slope of the thermopile in a lookup table based upon the temperature of the cold junction;

measuring the output signal of the thermopile; and

calculating a temperature based upon a linear relationship defining temperature as a function of the output signal of the thermopile in terms of the bias and the slope.

3. An infrared thermometer for measuring temperature on a subject'"'"'s forehead, the thermometer comprising:

a detector head having a metal heat sink;

a thermopile sensor mounted on the front end of the heat sink;

a first temperature sensor for measuring a cold junction temperature of the thermopile sensor;

a second temperature sensor for fast measurement of a room ambient temperature; and

an electronic circuit to calculate the temperature of the subject based in part upon the input of the second temperature sensor.