Rain sensor embedded on printed circuit board

1. A rain sensor for a vehicle, comprising:

a printed circuit board (PCB) to be supported by a vehicle window, the PCB comprising first and second outer layers and at least one inner layer, the first outer layer adapted to be closest to an interior of the vehicle and the second outer layer adapted to be closest to an exterior of the vehicle;

first and second capacitor arrays, the first capacitor array being formed on an outer surface of the first outer layer of the PCB and the second capacitor array being formed on an outer surface of the second outer layer of the PCB, one or more sensing capacitors in at least one of the first and second capacitor arrays being sensitive to moisture on an external surface of the window; and

programmed logic circuitry configured to distinguish between at least moisture on the exterior surface of the vehicle window, humidity on the interior surface of the vehicle window, and EMI,

wherein the at least one inner layer is arranged so as to decouple the first and second capacitor arrays and to shield the first capacitor array from fields emanating from the second capacitor array, and vice versa, and

wherein EMI is detected when the first and second capacitor arrays detect identical or similar signals substantially simultaneously.

2. The rain sensor of claim 1 , further comprising first and second inner layers, the first and second inner layers being substantially metallic.

3. The rain sensor of claim 1 , wherein the first and second outer layers are formed from a flexible polymer.

4. The rain sensor of claim 1 , wherein the rain sensor is bonded to the vehicle window via an adhesive tape, and wherein the rain sensor is supported by an interior surface of the vehicle window.

5. The rain sensor of claim 1 , wherein an opaque layer is provided on the window so as to shield the PCB from a view of a passenger inside the vehicle.

6. The rain sensor of claim 1 , wherein the opaque layer is a black frit.

7. The rain sensor of claim 1 , wherein each of the first and second capacitor arrays includes at least two sensing capacitors, and wherein at least part of at least one of the sensing capacitors in the first and/or second capacitor arrays has a fractal geometry.

8. The rain sensor of claim 7 , wherein the fractal geometry is selected from the group consisting of a Hilbert fractal and a Cantor fractal.

9. The rain sensor of claim 1 , wherein the window is one of a vehicle windshield, a vehicle backlite, and/or a vehicle sunroof.

10. The rain sensor of claim 1 , further comprising means for autocorrelating data relating to and/or from the first and/or second capacitor array to obtain autocorrelated data, and means for determining based at least on said autocorrelated data whether moisture is present on the external surface of the window.

11. The rain sensor of claim 1 , further comprising at least one correlating engine that (a) autocorrelates information from, and relating to, the first and second capacitor arrays to determine whether moisture is present on the exterior surface of the window, and (b) cross-correlates information from, and relating to, the first and second capacitor array to determine how fast to operate at least one wiper of a vehicle and/or an amount of moisture on the external surface of the window.

12. The rain sensor of claim 1 , wherein the vehicle window comprises first and second substantially parallel spaced apart substrates, and wherein the rain sensor is supported by an interior surface of the first or second substrate.

13. The rain sensor of claim 1 , wherein the vehicle window comprises first and second substantially parallel spaced apart substrates and a polymer-inclusive interlayer, and wherein the rain sensor is sandwiched between the first and second substrates in the polymer-inclusive interlayer, and wherein one or more sensing capacitors in each of the first and second capacitor arrays is sensitive to moisture on an external surface of the window.

14. A flexible printed circuit board (PCB) supported by a vehicle window, comprising:

a first outer layer, the first outer layer being closest to an interior of the vehicle and comprising a flexible polymer;

a second outer layer, the second outer layer being closest to an exterior of the vehicle and comprising a flexible polymer;

a first capacitor array comprising a first plurality of sensing capacitors on the first outer layer of the PCB;

a second capacitor array comprising a second plurality of sensing capacitors on the second outer layer of the PCB to be closest to the vehicle window;

programmed logic circuitry configured to distinguish between moisture on the exterior surface of the vehicle window, humidity on the interior surface of the vehicle window, and EMI, in dependence on signals generated by the first and second capacitor arrays; and

at least one substantially metallic inner layer arranged so as to substantially decouple the first and second capacitor arrays and to substantially shield the first capacitor array from fields emanating from the second capacitor array,

wherein the first and second capacitor arrays are formed on opposing surfaces of the flexible PCB, and

wherein EMI is detected when the first and second capacitor arrays detect identical or similar signals substantially simultaneously.

15. The flexible PCB of claim 14 , wherein at least part of at least one of the sensing capacitors in the first and/or second capacitor arrays has a fractal geometry.

16. The flexible PCB of claim 15 , wherein the fractal geometry is selected from the group consisting of a Hilbert fractal and a Cantor fractal.

17. The flexible PCB of claim 14 , wherein at least part of at least one of the sensing capacitors in the first and/or second capacitor arrays has a fractal structure, and wherein the different fractal structures have different sizes or patterns.

18. The flexible PCB of claim 17 , wherein the different fractal structures have different orientations, and may or may not have the same pattern and/or size.

19. The flexible PCB of claim 14 , further comprising:

circuitry configured to autocorrelate data relating to and/or from the first and/or second capacitor array to obtain autocorrelated data; and

circuitry configured to determine, based at least on said autocorrelated data, whether moisture is present on the external surface of the window.

20. The flexible PCB of claim 14 , further comprising correlating programmed logic circuitry configured to (a) autocorrelate information from, and/or relating to, the first and/or second capacitor array to determine whether moisture is present on the exterior surface of the window, and/or (b) cross-correlate information from, and/or relating to, the first and/or second capacitor array to determine how fast to operate at least one wiper of a vehicle and/or an amount of moisture on the external surface of the window.

21. The flexible PCB of claim 14 , wherein the first and second capacitor arrays are formed on opposing sides of the flexible PCB.

22. An electronic device mountable in or on a vehicle window, comprising:

a flexible printed circuit board (PCB);

first and second sensing circuits formed on opposing sides of the flexible PCB, each said sensing circuit comprising a plurality of different fractal structures;

a ground plane located between the first and second sensing circuits, the ground plane being arranged so as to decouple a first and second capacitor arrays and to shield the first capacitor array from fields emanating from the second capacitor array and vice versa,

wherein the electronic device is configured to detect moisture on an exterior surface of the vehicle window, humidity on an interior surface of the vehicle window, and EMI.