Frozen material detection using electric field sensor

• US 20070209446A1
• Filed: 03/10/2006
• Published: 09/13/2007
• Est. Priority Date: 03/10/2006
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: Stewart, Bradley, Wilson, David, de Alba Garcin, Sergio, Garcia, Rogelio, Barba, Gabriel
• Granted Patent: US 7,466,146 B2
• Time in Patent Office: Days
• US Class Current: 73/780
• CPC Class Codes: G01N 27/22 by investigating capacitance

Abstract

An electric field sensor may be used to detect accumulation of frozen material. In one embodiment, an e-field system includes a first electrode, a second electrode located at a distance from the first electrode, the second electrode forming a capacitive element with the first electrode, wherein a gap is present between the first and second electrodes, and an electric field sensor having an electrode terminal coupled to the first electrode and providing an electric field output value representative of an amount of frozen material located in the gap between the first and second electrodes. The system may also include a first insulator adjacent the first electrode and outside the gap, and a conductive layer adjacent the first insulator, where the first insulator is between the first electrode and the conductive layer, and where a shield output of the electric field sensor is coupled to the conductive layer.

Claims

1. An apparatus comprising:

a first electrode;

a second electrode located at a distance from the first electrode, the second electrode forming a capacitive element with the first electrode, wherein a gap is present between the first and second electrodes;

an electric field sensor having an electrode terminal coupled to the first electrode and providing an electric field output value representative of an amount of frozen material located in the gap between the first and second electrodes;

a first insulator adjacent the first electrode and outside the gap; and

a conductive layer adjacent the first insulator, wherein the first insulator is between the first electrode and the conductive layer, and wherein a shield output of the electric field sensor is coupled to the conductive layer.

2. The apparatus of claim 1, further comprising:

a coaxial cable, wherein the electrode terminal is coupled to the first electrode via a center conductor of the coaxial cable and wherein a shield output of the electric field sensor is coupled to the conductive layer via an outer shield of the coaxial cable.

3. The apparatus of claim 2, wherein the shield output maintains an approximately zero voltage differential between the center conductor and the outer shield.

4. The apparatus of claim 1, wherein the second electrode is subject to frost accumulation and the first electrode at least partially surrounds the second electrode.

5. The apparatus of claim 1, wherein each of the first electrode and second electrode partially surrounds a member subject to accumulation of frozen material, such that the gap is formed between edges of the first and second electrodes along lateral sides of the member.

6. The apparatus of claim 5, further comprising:

an insulating layer around the member, between the member and the first electrode layer and between the member and the second electrode; and

a conductive layer around the member, between the member and the insulating layer, wherein a shield output of the electric field sensor is coupled to the conductive layer.

7. The apparatus of claim 6, wherein the member is at least a portion of a cooling element.

8. The apparatus of claim 1, further comprising a refrigerator or air conditioner, the refrigerator or air conditioner comprising the first electrode, the second electrode, the electric field sensor, the first insulating layer, and the first conductive layer.

9. The apparatus of claim 1, further comprising a transportation device, the transportation device comprising the first electrode, the second electrode, the electric field sensor, the first insulating layer, and the first conductive layer.

10. The apparatus of claim 9, wherein the transportation device comprises a window, the window comprising the first and second electrodes.

11. The apparatus of claim 10, wherein the first and second electrodes each comprises indium titanium oxide.

12. The apparatus of claim 9, wherein the transportation device comprises a wing, the wing comprising the first and second electrodes.

13. An apparatus comprising:

a member subject to accumulation of frozen material;

a first electrode at least partially surrounding the member;

a second electrode at least partially surrounding the member and located at a first distance from the first electrode, the second electrode forming a capacitive element with the first electrode; and

an electric field sensor having a first electrode terminal coupled to the first electrode and providing an electric field output value representative of an amount of frozen material formed on the member between the first and second electrodes.

14. The apparatus of claim 13, further comprising:

a third electrode at least partially surrounding the member and located at a second distance from the first electrode, the first electrode between the second and third electrodes;

wherein the electric field sensor comprises a second electrode terminal coupled to the second electrode and a third electrode terminal coupled to the third electrode, and wherein when the first electrode terminal is enabled, the electric field output value is representative of an amount of frozen material formed on the member between the second and third electrodes.

15. The apparatus of claim 14, wherein when the first electrode terminal is enabled, the second electrode terminal couples the second electrode to ground and the third electrode terminal couples the third electrode to ground.

16. The apparatus of claim 13, further comprising:

a first insulating layer at least partially surrounding the first electrode;

a first conductive layer at least partially surrounding the first insulating layer, wherein a shield output of the electric field sensor is coupled to the first conductive layer;

a second insulating layer at least partially surrounding the second electrode; and

a second conductive layer at least partially surrounding the second insulating layer, wherein the shield output of the electric field sensor is coupled to the second conductive layer.

17. The apparatus of claim 16, wherein the first electrode, first insulating layer, and first conductive layer form concentric rings, and wherein the second electrode, second insulating layer, and second conductive layer form concentric rings.

18. The apparatus of claim 16, further comprising:

a third insulating layer at least partially surrounding the member, the third insulating layer between the member and the first electrode;

a third conductive layer at least partially surrounding the member, the third conductive layer between the member and the third insulating layer, wherein the shield output of the electric field sensor is coupled to the third conductive layer;

a fourth insulating layer at least partially surrounding the member, the fourth insulating layer between the member and the third conductive layer;

a fifth insulating layer at least partially surrounding the member, the fifth insulating layer between the member and the second electrode;

a fourth conductive layer at least partially surrounding the member, the fourth conductive layer between the member and the fifth insulating layer, wherein the shield output of the electric field sensor is coupled to the fourth conductive layer; and

a sixth insulating layer at least partially surrounding the member, the sixth insulating layer between the member and the fourth conductive layer.

19. The apparatus of claim 13, wherein the member subject to frozen material accumulation comprises a cooling element of a refrigerator or air conditioner.

20. An apparatus comprising:

a member subject to accumulation of frozen material;

a plurality of electrodes placed along the member, each of the plurality of electrodes spaced apart from each other; and

an electric field sensor having a plurality of electrode terminals, each of the plurality of electrode terminals coupled to a corresponding one of the plurality of electrodes, wherein when a first electrode terminal of the plurality of electrode terminals is selected, the electric field sensor provides an electric field output value representative of an amount of frozen material formed on the member between the electrodes of the plurality of electrodes adjacent a first electrode coupled to the first electrode terminal, and wherein each of the adjacent electrodes form a capacitive element with the first electrode.

21. The apparatus of claim 20, wherein the member subject to accumulation of frozen material comprises a window, a door, or a wing of a transportation device.

22. The apparatus of claim 20, wherein the member subject to accumulation of frozen material comprises a cooling element of a refrigerator or air conditioner.