Ice detection system

• US 6,879,168 B2
• Filed: 04/08/2002
• Issued: 04/12/2005
• Est. Priority Date: 04/08/2002
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Baas, Jack, Larson, Clayton
• Primary Examiner(s): Nguyen, Vincent Q.
• Application Number:
  US10/117,271
• Publication Number:
  US 20030189434A1
• Time in Patent Office: 1,100 Days
• Field of Search: 340/560, 340/962, 731/702.6, 324/71.1, 324/671, 324/699, 324/663, 324/661, 324/664, 324/691, 333/17.3, 333/32, 333/253, 333/263, 333/34, 438/17
• US Class Current: 324/671
• CPC Class Codes: G01N 27/221 by investigating the dielectric properties using microwaves G01N22/00; measuring loss factors or dielectric constants per se G01R27/26
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: G01N 27/226 Construction of measuring vessels; Electrodes therefor

Abstract

The invention is a system for determining the presence of ice on the surface of a structure. The system includes a guard layer mounted to the surface. A non-conductive layer is mounted on top of the ground plane. First and second electrodes made of a resistive material mounted on the non-conductive layer. First and second electrical leads having first ends of attached to first and second electrodes, respectively. The first and second leads having impedance equal to the impedance of the first ends thereof with the impedance of the first and second leads decreasing toward the second ends thereof.

Claims

1. A system for determining the presence of ice on an external surface of a structure, comprising:

a guard layer;

a non-conductive layer mounted on top of said guard layer;

first and second electrodes made of resistive material mounted on said non-conductive layer; and

first and second electrical leads having first and second ends, said first ends of said leads attached to first and second electrodes, respectively, said first and second leads having an impedance equal to the impedance of said first and second electrodes, with said impedance of said first and second leads decreasing toward said second ends thereof.

2. The system as set forth in claim 1 further comprising said first and second electrodes are parallel to each other in a spaced relationship.

3. The system as set forth in claim 2 wherein said resistive material of said pair of electrodes has impedance of 400 ohms per linear inch of length.

4. The system as set forth in claim 3 further comprising the resistivity of said guard layer decreasing from the area under said first and second electrodes toward the area under said second ends of said first and second leads.

5. The system as set forth in claim 4 further comprising the resistivity of said guard layer in said area under said first and second electrodes is 750 ohms per square and under said area under said second ends of said first and second leads is 50 ohms per square.

6. The system as set forth in claim 5 further comprising the resistivity of first and second leads decreasing from said first ends to a value of 50 ohms per square at said second ends.

7. The system as set forth in claim 6 further comprising a layer of semi-conductive material mounted over said first and second electrodes.

8. The system as set forth in claim 7 further including a coating of dielectric material covering said non-conductive layer surrounding said first and second electrodes and said semi-conductive material.

9. The system as forth in claim 8 wherein said external surface includes a recess and said non-conductive layer, said guard layer;

and said first and second electrodes are mountable in the recess, and said coating of dielectric material also fills the remaining portion of the recess.

10. The system as set forth in claim 9 further comprising said first and second leads extend parallel to each other in opposite directions to each other.

11. The system as set forth in claim 10 wherein the spacing of said electrodes is 0.10 inch.

12. A system for determining the presence of ice on an external surface of a structure, the device comprising:

a guard layer mountable to the surface;

a non-conductive layer mounted on top of said guard layer;

first and second electrodes made of resistive material mounted on said non-conductive layer in a parallel spaced relationship; and

first and second electrical leads having first and second ends, said first ends of said first and second leads attached to first and second electrodes, respectively, said first and second leads having said first ends thereof with an impedance equal to the impedance of said first and second electrodes with the impedance of said first and second leads decreasing toward said second ends thereof.

13. The system as set forth in claim 12 wherein said first and second leads separate from each other such that said second ends of said leads are substantially further apart than said first ends.

14. The system as set forth in claim 13, further comprising said first and second leads extend parallel to each other in opposite directions to each other.

15. The system as set forth in claim 14, further comprising the resistivity of said guard layer decreasing from the area under said first and second electrodes toward the area under said second ends of said first and second leads.

16. The system as set forth in claim 15, further comprising a layer of semi-conductive material mounted over said first and second electrodes.

17. The system as set forth in claim 16, further including a coating of dielectric material covering said non-conductive layer surrounding said first and second electrodes and said semi-conductive material.

18. The system as set forth in claim 17 wherein said external surface includes a recess and said non-conductive layer, said guard layer;

and said first and second electrodes are mounted in the recess, and said coating of dielectric material also fills the remaining portion of the recess.

19. The system as set forth in claim 15, or 16, or 17, or 18 wherein:

the resistive material of said pair of electrodes has impedance of 400 ohms per linear inch of length;

the resistivity of said guard layer in said area under said first and second electrodes is 750 ohms per square and under said area under said second ends of said first and second leads is 50 ohms per square; and

the resistivity of said first and second leads decreasing from said first ends to a value of 50 ohms per square at said second ends.

20. A structure including an ice detection system, comprising:

a guard layer;

a non-conductive layer mounted adjacent said guard layer;

first and second electrodes adjacent said non-conductive layer; and

first and second electrical leads coupled to respective said first and second electrodes, wherein the resistivity of said guard layer tapers from one end of said first and second electrical leads to another end of said first and second electrical leads.

21. The structure as set forth in claim 20 wherein said first and second electrical leads have an impedance approximately equal to the impedance of said first and second electrodes, and the impedance of said first and second leads increases toward said respective first and second electrodes.

22. The structure as set forth in claim 20 wherein said first and second electrodes include resistive material.

23. The structure as set forth in claim 20 further comprising a layer of semi-conductive material mounted over said first and second electrodes.

24. The structure as set forth in claim 23 further including a coating of dielectric material covering said non-conductive layer surrounding said first and second electrodes and said semi-conductive material.

25. The structure as forth in claim 20 wherein the ice detection system is mounted in, and substantially fills, a recess in the external surface of the structure.