Moisture detection system and method of use thereof

• US 20030159504A1
• Filed: 12/03/2002
• Published: 08/28/2003
• Est. Priority Date: 02/28/2002
• Status: Active Grant

• Current Assignee: Pittsburgh Glass Works LLC (LKQ Corporation)
• Original Assignee: PPG Industries Ohio Incorporated (Nouryon BV)
• Inventors: Koram, Kwaku Koi, Barguirdjian, Pascal, Haigron, Michel, Hawk, Allan Rex
• Granted Patent: US 6,802,205 B2
• Time in Patent Office: Days
• US Class Current: 73/170.17
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10293 Edge features, e.g. inserts or holes
• CPC Class Codes: B60S 1/0822 characterized by the arrangement or type of detection means
• CPC Class Codes: B60S 1/0829 Oscillator-resonator rain sensor
• CPC Class Codes: B60S 1/0877 at least part of the sensor being positioned between layers of the windshield
• CPC Class Codes: G01F 23/261 for discrete levels
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825

Abstract

A moisture detection system includes an electrical conductor disposed on a surface of a substrate. The electrical conductor has a resonant frequency that varies as a function of an amount of moisture present adjacent the electrical conductor. An oscillator outputs an oscillator signal at a predetermined amplitude and a predetermined frequency. A resonator circuit is coupled to the electrical conductor and is responsive to the oscillator signal and the resonant frequency of the electrical conductor for outputting a resonator signal having an amplitude related to the resonant frequency of the electrical conductor. A filter circuit rectifies and filters the resonator signal and provides it to an analog-to-digital converter which outputs a digital signal related to the rectified and filtered resonator signal. A controller is responsive to the digital signal for causing a system associated with the substrate to operate in accordance with the digital signal.

Claims

1. A moisture detection system comprising:

an electrical conductor disposed on a surface of a substrate and having a resonant frequency that varies as a function of an amount of moisture present adjacent the electrical conductor;

an oscillator which outputs an oscillator signal at a predetermined amplitude and a predetermined frequency;

a resonator circuit coupled to the electrical conductor and responsive to the oscillator signal for outputting a resonator signal having an amplitude related to the resonant frequency of the electrical conductor;

a filter circuit responsive to the resonator signal for outputting a rectified and filtered signal;

an analog-to-digital converter responsive to the rectified and filtered signal for outputting a digital signal related to the rectified and filtered signal; and

a controller responsive to the digital signal for causing another system to operate in accordance with the digital signal.

2. The system as set forth in claim 1, wherein the other system is a wiper system that is responsive to the controller for adjusting a rate moisture is removed from adjacent the electrical conductor as a function of an amount of moisture present adjacent the electrical conductor and/or a rate moisture accumulates adjacent the electrical conductor.

3. The system as set forth in claim 2, wherein:

the wiper system includes a means for wiping; and

the wiper system is responsive to the digital signal for causing the wiping means to remove moisture from a surface.

4. The system as set forth in claim 1, wherein the predetermined frequency is between one of (i) 300 and 700 kHz and (ii) 400 and 600 kHz.

5. The system as set forth in claim 1, wherein:

the substrate is a vehicle windshield having a plurality of transparent sheets laminated together; and

the electrical conductor is sandwiched between the sheets.

6. The system as set forth in claim 1, wherein the substrate is a flexible substrate.

7. The system as set forth in claim 6, further including a vehicle windshield having a plurality of transparent sheets laminated together with the flexible substrate sandwiched between the transparent sheets.

8. The system as set forth in claim 7, further including an electrically conductive coating disposed on a surface of at least one transparent sheet.

9. The system as set forth in claim 8, wherein said surface is positioned on a side of the flexible substrate opposite the electrical conductor.

10. The system as set forth in claim 6, wherein the flexible substrate further includes at least one of (i) a ground conductor disposed on the flexible substrate at least partially surrounding the electrical conductor and (ii) a conductive material disposed on a surface of the flexible substrate opposite the electrical conductor, said conductive material having a form that defines a faraday shield.

11. The system as set forth in claim 1, wherein the resonator circuit includes:

a tank circuit having a capacitor and an inductor connected in parallel between the electrical conductor and a reference voltage; and

a resistor connected between the oscillator and the electrical conductor side of the tank circuit.

12. The system as set forth in claim 1, wherein the filter circuit includes:

a diode connected to conduct current from the resonator toward the analog-to-digital converter; and

a capacitor connected between an end of the diode adjacent the analog-to-digital converter and a reference voltage.

13. A moisture detector system comprising:

means disposed on a substrate for conducting electrical current, the conducting means having a resonant frequency that changes as a function of moisture adjacent the conducting means;

an oscillator for outputting to the conducting means an oscillator signal having a predetermined frequency and a first amplitude;

means responsive to the oscillator signal for outputting a resonator signal having a second amplitude related to the resonant frequency of the conducting means, wherein the second amplitude is different than the first amplitude; and

means responsive to the resonator signal for outputting a control signal having a value related to the second amplitude of the resonator signal.

14. The moisture detector as set forth in claim 13, further including a wiper system responsive to the control signal for wiping moisture from adjacent the conducting means based on an amount of moisture adjacent the conducting means and/or a rate moisture accumulates adjacent the conducting means.

15. The moisture detector as set forth in claim 13, wherein the conducting means includes at least one of (i) one or more lines of conductive material, (ii) one or more sheets of conductive material, and (iii) a dispersion of conductive particles in the form of one or more lines and/or sheets.

16. The moisture detector as set forth in claim 13, wherein the substrate is a windshield that includes plural sheets of glass laminated together.

17. The moisture detector as set forth in claim 16, wherein the conducting means is sandwiched between the sheets of glass.

18. The moisture detector as set forth in claim 13, wherein:

the substrate is a flexible substrate that is coupled to a sheet; and

the conducting means has a resonant frequency that changes as a function of moisture on the sheet.

19. The moisture detector as set forth in claim 18, further including a wiper system disposed in operative relation to the sheet and responsive to the control signal for wiping the sheet based on an amount of moisture on the sheet and/or a rate moisture accumulates on the sheet.

20. The moisture detector as set forth in claim 18, wherein the conducting means includes one or more lines of electrically conductive material disposed on the flexible substrate.

21. The moisture detector as set forth in claim 18, wherein the sheet is a windshield that includes plural sheets of glass laminated together.

22. The moisture detector as set forth in claim 21, wherein the flexible substrate is sandwiched between the sheets of glass.

23. The moisture detector as set forth in claim 18, wherein the flexible substrate further includes at least one of (i) a ground conductor disposed on the flexible substrate at least partially surrounding the conducting means and (ii) a conductive material disposed on a surface of the flexible substrate opposite the conducting means, said conductive material having a form that defines a faraday shield.

24. The moisture detector as set forth in claim 21, further including an electrically conductive coating disposed on a surface of at least one sheet.

25. The moisture detector as set forth in claim 24, wherein said surface is positioned on a side of the flexible substrate opposite the conducting means.

26. A method of moisture detection comprising:

(a) providing a substrate having an electrical conductor disposed thereon;

(b) stimulating the electrical conductor with an oscillator signal in the absence of moisture adjacent the electrical conductor;

(c) determining a first amplitude of the electrical conductor to the stimulation in step (b);

(d) stimulating the electrical conductor with the oscillator signal when moisture is present adjacent the electrical conductor;

(e) determining a second amplitude of the electrical conductor to the stimulation in step (d), wherein the second amplitude is different than the first amplitude due to a change in resonant frequency of the electrical conductor in response to the presence of moisture adjacent the electrical conductor; and

(f) determining a difference between the first amplitude and the second amplitude, wherein the difference is related to the amount of moisture present adjacent the electrical conductor.

27. The method as set forth in claim 26, further including removing moisture from adjacent the electrical conductor at a rate related to the difference between the first amplitude and the second amplitude.

28. The method as set forth in claim 26, further including sandwiching the substrate between at least two sheets of glass.

29. The method as set forth in claim 28, further including providing shielding means on at least one of (i) the substrate and (ii) at least one of the sheets of glass.

30. The method as set forth in claim 28, wherein the substrate is flexible.

31. A moisture detection system comprising:

a substrate;

an electrical conductor disposed on the substrate;

means for stimulating the electrical conductor with an oscillator signal; and

means responsive to the oscillator signal and the electrical conductor for detecting changes in a resonant frequency of the electrical conductor in response to changes in an amount of moisture disposed adjacent the electrical conductor.

32. The system as set forth in claim 31, wherein the substrate is flexible.

33. The system as set forth in claim 31, further including a sheet in contact with the substrate.

34. The system as set forth in claim 33, further including:

means for removing an accumulation of moisture on the sheet; and

means responsive to the detecting means for controlling when the removing means removes the accumulation of moisture from the sheet.

35. The system as set forth in claim 34, wherein the substrate is disposed on one of (i) a side of the sheet receiving the accumulation of moisture and (ii) a side of the sheet not receiving the accumulation of moisture.

36. The system as set forth in claim 33, wherein the sheet is formed from a plurality of sheets joined together.

37. A moisture detection system comprising:

a fluid reservoir;

an electrical conductor disposed on the fluid reservoir;

means for stimulating the electrical conductor with an oscillator signal; and

means responsive to the oscillator signal and the electrical conductor for detecting a change in a resonant frequency of the electrical conductor responsive to a change in a level of fluid in the fluid reservoir and for outputting a control signal when the detected change in the resonant frequency of the electrical conductor corresponds to less than a desired level of fluid in the fluid reservoir.

38. The moisture detection system of claim 37, wherein the electrical conductor is disposed on a flexible substrate positioned on the fluid reservoir.