Method and apparatus for a non-contact measuring of a temperature of a body

• US 4,887,229 A
• Filed: 06/22/1987
• Issued: 12/12/1989
• Est. Priority Date: 06/20/1986
• Status: Expired due to Fees

• Current Assignee: Martin Lehmann
• Original Assignee: Martin Lehmann
• Inventors: Weiss, Hardy P.
• Primary Examiner(s): Yasich, Daniel M.
• Application Number:
  US07/064,464
• Time in Patent Office: 904 Days
• Field of Search: 374/132, 374/133, 374/129, 374/170, 374/128, 250/352, 364/571, 364/571.03, 364/557
• US Class Current: 702/131
• CPC Class Codes: G01J 5/064 Ambient temperature sensor; Housing temperature sensor; Constructional details thereof
• CPC Class Codes: G01J 5/0805 Means for chopping radiation
• CPC Class Codes: G01J 5/34 using capacitors, e.g. pyroelectric capacitors

Abstract

A method and apparatus for measuring a temperature of a body extensively independently of an interference radiation. The apparatus comprising a sensor wherein a radiation of the body is chopped or interrupted by a chopper disposed between the sensor and a body. In order to sense extraneous radiation which originates predominately from losses at the sensor as well as from frictional heat of the chopper, the housing temperature of the sensor is detected for correction purposes on a side of the chopper facing the sensor by an additional sensor. Around and in the zone of the travel path of the chopper, an additional sensor is provided for sensing an ambient temperature of the chopper.

Claims

1. A measuring apparatus for a non-contact measurement of a temperature of a body, the apparatus comprising:

a first temperature sensor means for measuring a temperature of heat radiation received from a direction toward said body;

a heat radiation chopper means disposed in front of a heat input region of the first temperature sensor means for chopping heat radiation;

at least one second temperature sensor means arranged adjacent at least one of the chopper means;

a multiplication unit connected after an output of the at least one second temperature sensor means wherein, a signal of an adjustable value signal is fed to the second input of the multiplication unit, an output of the multiplication unit is fed to a summation unit, an adjustable value signal is fed as a second input to said summation unit, an output of the first temperature sensor means is transmitted to a numerator input of a dividing unit, a denominator input of the dividing unit is fed with an output signal of the summation unit; and

wherein an output of the dividing unit as well as an output from the second temperature sensor means are transmitted to a summation unit, and an output of which represents the temperature of the body.

2. A measuring apparatus according to claim 1, further comprising:

storage means for storing said adjustable value signals, said storage means being connected to said inputs of said multiplication unit and said summation unit respectively.

3. An apparatus according to claim 1, wherein:

at least one further temperature sensor means is closely thermally coupled with a housing means for housing said first temperature sensor means.

4. An apparatus according to claim 3, wherein:

said further temperature sensor means is connected as a controlled variable pick-up to a temperature feed-back control circuit means for providing a controlled temperature of said housing means.

5. An apparatus according to claim 1, wherein:

said second temperature sensor means is closely thermally coupled with said chopper means.

6. An apparatus according to claim 1, wherein;

said chopper means id mechanically moving; and

wherein said second temperature sensor means is arranged in an area along a path of motion of said chopper means.

7. An apparatus according to claim 1, further comprising:

storage means for storing at least one of two predetermined value signals.

8. An apparatus according to claim 1, wherein:

at least one of said first and second temperature sensor means includes time averaging means; and

wherein an average time is longer than a chopper period of said chopper means.

9. An apparatus according to claim 1, wherein:

at least said first temperature sensor means is a pyroelectrical thermal sensor.

10. An apparatus according to claim 1, further comprising:

threshold value sensitive means, connected at an output of said first temperature sensor means, for providing an output operatively connecting said output of said first temperature sensor means to said numerator input of said dividing unit when said output signal of said first temperature sensor means crosses a threshold value.

11. An apparatus according to claim 10, wherein:

said threshold value sensitive means responds to a predetermined change of heat radiation per unit of time as detected by said first temperature sensor means due to said chopper means.

12. An apparatus according to claim 1, wherein:

said first temperature sensor means senses changes in heat radiation per unit of time.

13. An apparatus according to claim 1, wherein said at least one second temperature sensor means is arranged on the side of said chopper means facing said first temperature sensor means.

14. A method for a non-contact measurement of a temperature of a body, the method comprising the steps of:

interrupting a heat radiation between the body and a temperature sensor means by a chopper means;

detecting at least one ambient temperature;

multiplying a first signal dependent on said ambient temperature by a first coefficient;

adding a result of the multiplication to a second coefficient to obtain a second signal;

detecting a third signal dependent upon the temperature detected by the sensor means and dividing the same by the second signal in order to obtain a fourth signal; and

adding the fourth signal to the first signal to obtain a signal representing a temperature of the body.

17. A method according to claim 14, further comprising the step of:

detecting a temperature of a housing means accommodating said temperature sensor means.

18. A method according to claim 17, further comprising the step of:

controlling said temperature of said housing means to a predetermined value.

19. A method according to claim 14, wherein the step of:

detecting at least one ambient temperature includes a step of detecting an ambient temperature influenced by heat generated by operation of said chopper means.

20. A method according to claim 14, further comprising the steps of:

mechanically moving said chopper means to interrupt the heat radiation; and

wherein the step of detecting at least one ambient temperature includes a step of detecting a temperature in vicinity of a travel path of said chopper means.

21. A method according to claim 14 further comprising the step of:

providing said body with a recess and placing said body with said recess facing said temperature sensor means.

22. A method according to claim 14, further comprising the steps of:

providing said body with a recess and moving said body with said recess relative to said sensor means; and

choosing a chopper period of said chopper means less than a time-span during which said recess lies within a measuring range of said sensor means.

23. A method according to claim 22, further comprising the steps of:

monitoring an output signal of said temperature sensor means for occurrence of a predetermined threshhold value, which indicates appearance of said recess within said measuring range; and

using said output signal as said third signal when said predetermined characteristic occurs.

24. A method according to claim 23, wherein:

said predetermined characteristic is a predetermined jump in amplitude of impulses on said output signal, due to said chopper means.

25. A method according to claim 14, wherein:

a time derivative of heat radiation is detected by said temperature sensor means.

26. The method according to claim 14, wherein said at least one second temperature sensor means is arranged on a side of said chopper means facing said first temperature sensor mean.

27. The method according to claim 14, wherein said first temperature sensor means senses heat radiation.

15.

16.