Rain sensor for detecting rain or other material on window of a vehicle or on other surface

• US 20070162201A1
• Filed: 01/27/2006
• Published: 07/12/2007
• Est. Priority Date: 01/10/2006
• Status: Active Grant

• Current Assignee: Guardian Glass LLC (KOCH Industries Incorporated)
• Original Assignee: Guardian Industries Corporation (KOCH Industries Incorporated)
• Inventors: Veerasamy, Vijayen
• Granted Patent: US 7,516,002 B2
• Time in Patent Office: Days
• US Class Current: 701/36
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10174 Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
• CPC Class Codes: B32B 17/10761 containing vinyl acetal
• CPC Class Codes: B60S 1/0818 including control systems responsive to external conditions, e.g. by detection of moisture, dirt or the like
• CPC Class Codes: B60S 1/0822 characterized by the arrangement or type of detection means
• CPC Class Codes: B60S 1/0825 Capacitive rain sensor
• CPC Class Codes: G06V 20/56 exterior to a vehicle by using sensors mounted on the vehicle

Abstract

A system and/or method for sensing the presence of moisture (e.g., rain) and/or other material(s) on a window such as a vehicle window (e.g., vehicle windshield or backlite). In certain example embodiments, a capacitor-based system and/or method is provided for auto-correlating sensor data to determine the existence of a material on the window, and then cross-correlating sensor data to identify the type and/or amount of that material (e.g., rain). This data may be used to actuate and/or deactivate a vehicle'"'"'s wiper(s), and/or adjust wiper speed. In certain example embodiments, the sensor may include an array of at least two capacitors. In certain example embodiments, the system and/or method may perform check(s) to enhance the accuracy of the detection by comparing, for example, the sign of autocorrelation values, maximum autocorrelation values, and/or gradients of autocorrelation values

Claims

1. A method of sensing the presence of moisture on a vehicle window, the method comprising:

receiving data relating to at least two capacitors supported by the vehicle window;

autocorrelating the data relating to each capacitor to obtain autocorrelated data; and

determining, based at least on said autocorrelated data, whether moisture is present on an exterior surface of the vehicle window.

2. The method of claim 1, further comprising:

cross-correlating the data relating to the two capacitors so as to correlate data relating to different capacitors to obtain cross-correlated data; and

determining, based at least on said cross-correlated data, a type and/or amount of moisture on the exterior surface of the vehicle window.

3. The method of claim 2, wherein said cross-correlating is performed after said autocorrelating when certain condition(s) is/are met, and wherein said determining based on at least the cross-correlated data determines the type of moisture on the window, where the type is one or more of:

light rain, heavy rain, fog, sleet, snow, ice, and wherein the vehicle window is a windshield or a backlite.

4. The method of claim 1, further comprising sigma-delta modulating the data relating to the two capacitors, thereby providing analog-to-digital conversion and digital data, and wherein said autocorrelating uses the digital data.

5. The method of claim 1, further comprising checking said autocorrelated data for negative values.

6. The method of claim 5, wherein, when the autocorrelated data has negative values, indicating that it is not raining and/or parking at least one wiper of the vehicle.

7. The method of claim 1, further comprising calculating whether a gradient of an autocorrelation curve associated with said autocorrelated data is greater than a predetermined value.

8. The method of claim 7, wherein when the gradient is not greater than the predetermined value, then indicating that it is not raining and/or parking at least one wiper of the vehicle.

9. The method of claim 1, further comprising determining whether there is a match or a substantial match between an autocorrelation curve associated with the autocorrelated data and one or more predetermined autocorrelation curve(s) stored in a database.

10. The method of claim 9, further comprising, when there is a match or substantial match between the autocorrelation curve associated with the autocorrelated data and the predetermined autocorrelation curve, indicating that it is not raining, parking at least one wiper of the vehicle and/or not actuating wipers of the vehicle.

11. The method of claim 2, wherein said cross-correlating step is only performed when all of the following conditions are met:

(a) the autocorrelated data has no negative values;

(b) a gradient of an autocorrelation curve associated with said autocorrelated data is greater than a predetermined value; and

(c) the shape of the autocorrelation curve associated with the autocorrelated data is different than a predetermined autocorrelation curve associated with normalized non-disturbed autocorrelation data.

12. The method of claim 2, further comprising determining a symmetry level of a cross-correlation curve associated with the cross-correlated data.

13. The method of claim 1, wherein a capacitive array includes at least four capacitors, and autocorrelating data relating to each of the four capacitors to obtain autocorrelated data used for determining whether moisture is present.

14. The method of claim 1, wherein the data relating to the at least two capacitors, analog or digital, is received from circuitry that receives and/or reads capacitance data from the at least two capacitors, and wherein said capacitors are formed based on a fractal pattern.

15. The method of claim 1, wherein the data relating to the at least two capacitors may be analog or digital and is output from circuitry that:

(a) receives and/or reads data and/or signals from the at least two capacitors, and/or (b) includes a capacitor(s) or other circuit element(s) that mimics or substantially mimics one or more of charging, discharging and/or capacitance of the at least two capacitors.

16. The method of claim 1, wherein each of the capacitors comprises first and second spaced apart electrodes that are substantially coplanar with one another.

17. The method of claim 1, wherein at least one capacitor electrode of each of the two capacitors is floating so that the capacitors are isolated from ground.

18. A moisture sensor for sensing the presence of moisture on a vehicle window, the moisture sensor comprising:

at least two moisture sensing capacitors which are affected by moisture present on a surface of the vehicle window;

means for autocorrelating data relating to at least one of the capacitors to obtain autocorrelated data; and

means for determining, based at least on said autocorrelated data, whether moisture is present on the vehicle window.

19. The moisture sensor of claim 18, further comprising:

means for cross-correlating data relating to the two capacitors so as to correlate data from different capacitors to obtain cross-correlated data; and

means for determining, based at least on said cross-correlated data, a type and/or amount of moisture on the window.

20. The moisture sensor of claim 19, further comprising means for determining how fast to operate at least one wiper of the vehicle based on the cross-correlated data.

21. The moisture sensor of claim 18, wherein the data relating to the at least two capacitors is digital and has been sigma-delta modulated prior to reaching the means for autocorrelating.

22. The moisture sensor of claim 18, further comprising means for checking said autocorrelated data for negative values, and means for, when the autocorrelated data has negative values, indicating that it is not raining and/or parking wipers of the vehicle.

23. The moisture sensor of claim 18, further comprising means for calculating whether a gradient of an autocorrelation curve associated with said autocorrelated data is greater than a predetermined value(s).

24. The moisture sensor of claim 18, wherein each of the capacitors comprises first and second spaced apart electrodes that are substantially coplanar with one another.

25. The moisture sensor of claim 18, wherein at least one capacitor electrode of each of the two capacitors is floating so that the capacitors are isolated from ground.

26. A method of sensing the presence of moisture on a vehicle window such as a windshield or backlite, the method comprising:

correlating capacitor data to obtain correlated data;

determining, based at least on said correlated data, (a) whether moisture is present on an exterior surface of the vehicle window, and/or (b) a type and/or amount of material present on an exterior surface of the vehicle window.

27. The method of claim 26, wherein said correlating is autocorrelating and/or cross-correlating.

28. A method of engaging windshield wipers in response to detected rain, the method comprising:

receiving data relating to a capacitive array including at least two capacitors supported by a vehicle windshield;

mathematically comparing data relating to one or more of the capacitors with data from that same capacitor, and based at least on said comparing determining whether it is raining;

mathematically comparing data relating to different capacitors of the array to obtain mathematically compared data from different capacitors, and based at least thereon determining how fast to operate the wipers of the vehicle and/or an amount of rain falling.

29. A rain sensor comprising:

at least two sensing devices that are affected by rain on a surface of a window;

circuitry that provides an output related to the sensing devices; and

at least one correlating engine that (a) autocorrelates information from said circuitry to determine whether rain is present, and/or (b) cross-correlates information from said circuitry to determine how fast to operate at least one wiper of a vehicle and/or an amount of rain.