Apparatus and method for temperature measurement by radiation

• US 5,127,742 A
• Filed: 04/19/1991
• Issued: 07/07/1992
• Est. Priority Date: 04/19/1991
• Status: Expired due to Fees

• Current Assignee: Thermoscan Incorporated (The Procter & Gamble Company)
• Original Assignee: Thermoscan Incorporated (The Procter & Gamble Company)
• Inventors: Fraden, Jacob
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): GUTIERREZ, DIEGO F
• Application Number:
  US07/688,014
• Time in Patent Office: 445 Days
• Field of Search: 374/129, 374/126, 374/123, 374/130, 374/128, 356/43
• US Class Current: 374/129
• CPC Class Codes: G01J 2005/063 Heating; Thermostating
• CPC Class Codes: G01J 5/0805 Means for chopping radiation
• CPC Class Codes: G01J 5/532 using a reference heater of the emissive surface type, e.g. for selectively absorbing materials

Abstract

A thermal radiation sensor is joined with a shutter that is adapted for reversible interruption of radiation from an object to the sensor. The shutter includes an integral electrically operated heater for maintaining a portion of the shutter at a predetermined temperature as a thermal reference for the sensor. The sensor is alternatively exposed to radiation from the object and the thermal reference portion of the shutter, and provides a first signal representative of the radiation that it receives from the object and a second signal representative of the radiation that it receives from the reference portion. An electronic circuit is connected to the sensor for receiving the first and second signals, for calculating the temperature of the object, and for providing a signal representative of the calculated temperature.

Claims

1. An apparatus for measuring the temperature of an object by thermal radiation, said apparatus comprising:

a thermal radiation sensor for receiving radiation from said object;

shutter means adapted for reversible interruption of said radiation from said object to said sensor,

electrically operated means forming an integral part of a portion of said shutter means for maintaining said portion of said shutter means at a predetermined temperature for comprising a thermal reference portion for said sensor,

means for alternatively exposing said thermal radiation sensor to radiation from said object and to radiation from said thermal reference portion of said shutter means,

said thermal radiation sensor also being for providing a first signal representative of the radiation it receives from said object, and a second signal representative of the radiation it receives from said portion,

electronic circuit means connected to said sensor for receiving said first signal and said second signal, for calculating the temperature of said object, and for providing a signal representative of said calculated temperature.

2. The apparatus for measuring the temperature of an object by thermal radiation as described in claim 1, further comprising:

said electrically operated means integral with said portion for maintaining said portion of said shutter means at a predetermined temperature comprising;

electrically operated means for changing the temperature of said portion of said shutter means, and means for measuring the temperature of said portion of said shutter means and for providing a third signal representative of the temperature of said portion of said shutter means, attached to said shutter means, and

control means, connected to said means for measuring, for receiving said third signal, and for electrically operating said means for changing.

3. The apparatus for measuring the temperature of an object by thermal radiation as described in claim 2, further comprising:

said means for changing the temperature, and said means for measuring the temperature of said portion, being mounted on said shutter means in superimposed layers.

4. The apparatus for measuring the temperature of an object by thermal radiation as described in claim 2, further comprising:

said shutter means comprising a thermally conductive wall comprising said means for changing the temperature, and said means for measuring the temperature of said portion.

5. The apparatus for measuring the temperature of an object by thermal radiation as described in claim 1, further comprising:

said means for maintaining said portion of said shutter means at a predetermined temperature comprising a self-temperature regulating element integral with said shutter.

8. The apparatus for measuring the temperature of an object by thermal radiation as described in claim 1, further cmprising:

said shutter means comprising two thermal reference portions.

9. The apparatus for measuring the temperature of an object by thermal radiation as described in claim 1, further comprising:

said shutter means comprising two optical pathways.

6. The apparatus for measuring the temperature of an object by thermal radiation as described in calim 1, further comprising:

said shutter means comprising two thermal reference portions and further, two portions of said shutter means comprising optical pathways for radiation from said object to said sensor.

7. The apparatus for measuring the temperature of an object by thermal radiation as described in claim 6, further comprising:

said shutter means comprising rotary means for alternatively exposing said sensor to a thermal reference portion and an optical pathway.

10. A method for measuring the temperature of an object by thermal radiation, said method comprising:

bringing a thermal reference portion of a shutter to a predetermined temperature by electrically operating means for changing temperature which is integral with said shutter, then

alternatively exposing a thermal radiation sensor to the thermal reference portion, while said shutter is positioned for interrupting radiation from said object to said sensor, and

moving said shutter for providing an optical pathway for exposing said sensor to radiation from said object to said sensor, and

processing signals from said sensor caused by the exposure of said sensor to said shutter and to said object, for determining the temperature of the object.

11. The method for measuring the temperature of an object by thermal radiation as described in claim 10, said method further comprising:

moving said shutter in an arc for alternating said exposures.

12. The method for measuring the temperature of an object by thermal radiation as described in claim 10, said method further comprising:

said processing of said signal including the equation ##EQU2## where;

T_b is the temperature of the object,

T_a is the predetermined reference temperature of the thermal reference portion of the shutter,

n is a constant, and

V is an output signal of the sensor.