Rain sensor with sigma-delta modulation and/or footprinting comparison(s)

• US 7,775,103 B2
• Filed: 01/12/2009
• Issued: 08/17/2010
• Est. Priority Date: 01/10/2006
• Status: Expired due to Fees

• Current Assignee: Guardian Glass LLC (KOCH Industries Incorporated)
• Original Assignee: Guardian Industries Corporation (KOCH Industries Incorporated)
• Inventors: Veerasamy, Vijayen S.
• Primary Examiner(s): Allen; Andre J
• Application Number:
  US12/318,912
• Publication Number:
  US 20090126476A1
• Time in Patent Office: 582 Days
• Field of Search: None
• US Class Current: 73/170.17
• 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, sunroof or backlite). In certain example embodiments of the invention, at least one sensing capacitor is supported by a window such as a vehicle windshield, the capacitor(s) having a field that is affected by moisture (e.g., rain) on a surface of the window. A sensing circuit outputs an analog signal that is based on and/or related to the capacitance(s) of the sensing capacitor(s). The analog output of the circuit may be converted to a digital signal via sigma-delta modulation, and subjected to processing (e.g., correlation) for determining whether moisture (e.g., rain, dew, fog, etc.) or the like is present on the surface of the window.

Claims

1. A method of determining whether moisture is present on an external surface of a vehicle window, the method comprising:

receiving a signal relating to at least one sensing capacitor, and processing the signal to obtain a signal footprint; and

comparing the signal footprint with one or more predetermined signal footprints stored in memory to determine whether a detected material on the external surface of the vehicle is moisture or some other material.

2. The method of claim 1, wherein said processing comprises autocorrelating digital data relating to the sensing capacitor to obtain autocorrelated data of the signal footprint.

3. The method of claim 1, wherein the rain sensor includes at least first and second sensing capacitors;

cross-correlating digital data relating to the sensing capacitors to obtain cross-correlated data, and determining based at least on the cross-correlated data a type and/or amount of moisture on the external surface of the vehicle window.

4. The method of claim 1, wherein the signal fingerprint comprises an autocorrelation curve associated with autocorrelated data, and the predetermined signal footprint comprises a predetermined autocorrelation curve.