Method of image processing for off the glass rain sensing

• US 6,429,933 B1
• Filed: 03/12/1999
• Issued: 08/06/2002
• Est. Priority Date: 03/12/1999
• Status: Expired due to Term

• Current Assignee: Valeo Electrical Systems Incorporated (Valeo SE)
• Original Assignee: Valeo Electrical Systems Incorporated (Valeo SE)
• Inventors: Jackson, James A. Jr.
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Nguyen, Tu T.
• Application Number:
  US09/267,867
• Time in Patent Office: 1,243 Days
• Field of Search: 356/239.8, 356/238.3, 356/239.1, 356/239.2, 356/237.2, 356/237.3, 356/237.4, 356/237.5, 356/237.6, 356/239.7, 356/445, 250/208.1, 250/573, 250/227.25, 250/574, 318/483, 318/DIG.2, 318/480, 15D/IG.15, 340/602
• US Class Current: 356/239.8
• CPC Class Codes: B60S 1/0822 characterized by the arrangement or type of detection means
• CPC Class Codes: B60S 1/0844 including a camera
• CPC Class Codes: B60S 1/087 including an ambient light sensor control of vehicle lights B60Q
• CPC Class Codes: Y10S 15/15 Moisture responsive

Abstract

An assembly (10) for sensing moisture (20) on the exterior surface (22) of a windshield (14) from a position spaced from the interior surface (18) of the windshield (14). The assembly (10) includes a focal plane detector (12) comprising a plurality of pixels (24) adapted for disposition in spaced relationship to the interior surface (18) of the sheet of glass (14). An imaging lens (16) is adapted for disposition between the focal plane detector (12) and the interior surface (18) of the sheet of glass (14) for directing light waves from moisture (20) on the exterior surface (22) of the sheet of glass (14) through the imaging lens (16) to produce successive images of the moisture (20) on the focal plane detector (12).

Claims

1. A method for sensing moisture (20) on the exterior surface (22) of a sheet of glass (14) comprising the steps of;

positioning an imaging lens (16) adjacent to the interior surface (18) of the sheet of glass (14),

passing light waves from moisture (20) on the exterior surface (22) of the sheet of glass (14) through the imaging lens (16) and producing first and second successive images of the moisture (20) on the glass (14), and

successively directing the first and second images from the lens (16) onto a focal plane detector (12),

dividing the first image into a plurality of elements (24) and producing an analog signal (26) corresponding to each of the elements,

dividing the second image into the plurality of elements (24) and producing an analog signal (26) corresponding to each of the elements,

storing the signals (26) from the elements (24) for the first image, storing the signals (26) from the elements (24) for the second image, comparing the signal from each element for the first image to the signal from that element for the second image, and providing a control signal (30) in response to predetermined differences between the signals (26) from the elements (24) for the first and second images.

2. A method as set forth in claim 1 including detecting the edges in the first and second images.

3. A method as set forth in claim 2 including algebraically summing the areas of the first and second images.

4. A method as set forth in claim 3 including determining the centers of mass of the second image.

5. A method as set forth in claim 4 including adjusting the contrast and brightness of the first and second images prior to detecting the edges.

6. An assembly as set forth in claim 1 including a light source (32) adapted for disposition in spaced relationship to the interior surface (18) of the sheet of glass (14) for directing light to the exterior surface (22) of the glass (14) whereby light waves generated by the light source (32) are directed from moisture (20) on the exterior surface (22) of the sheet of glass (14) through said imaging lens (16) to produce the first and second images of the moisture (20) on said focal plane detector (12).

7. A method as set forth in claim 1 including establishing a reference image level proportional to the analog signals (26) representing a non-moisture (20) condition of the exterior surface (22) of the glass (14), scanning each of the analog signals (26) and producing a wiper signal (30) in response to a deviation from the references image level.

8. A method as set forth in claim 7 including changing the reference image level in response to permanent changes in the non-moisture (20) condition of the exterior surface (22) of the glass (14).

9. A method as set forth in claim 1 including positioning a light source (32) adjacent to the interior surface (18) of the sheet of glass (14), directing light from the source to the exterior surface (22) of the glass (14), and wherein the step of passing of light waves is further defined as passing light waves generated by the light source (32) to produce the second image.

10. An assembly as set forth in claim 1 wherein said focal plane detector (12) comprises a plurality of pixels (24) for dividing the images into a plurality of elements and for producing an analog signal (26) corresponding to each of the elements.

11. An assembly for sensing moisture (20) on a glass (14) surface from a position adjacent the glass (14), said assembly comprising;

a focal plane detector (12) adapted for disposition adjacent to the interior surface (18) of the sheet of glass (14), and

said focal plane detector (12) including a plurality of elements (24) for producing an analog signal (26) corresponding to each of the elements,

an imaging lens (16) adapted for disposition between said focal plane detector (12) and the interior surface (18) of the sheet of glass (14) for directing light waves from moisture (20) on the exterior surface (22) of the sheet of glass (14) through said imaging lens (16) to produce successive first and second images of the moisture (20) on said focal plane detector (12),

said assembly characterized by a controller (28) for storing the signals (26) from the elements (24) for the first image and for storing the signals (26) from the elements (24) for the second image and for comparing the signal from each element for the first image to the signal from that element for the second image, and for providing a control signal (30) in response to predetermined differences between the signals (26) from the elements (24) for the first and second images.

12. An assembly as set forth in claim 11 wherein said controller (28) includes an edge detector (40) for detecting the edges in the first and second images and algebraically summing the areas of the first and second images.

13. An assembly as set forth in claim 12 wherein said controller (28) includes amass detector (42) for determining the centers of mass of the second image.

14. An assembly as set forth in claim 13 wherein said controller(28) includes an adjustor (44) for adjusting the contrast and brightness of the first and second images prior to detecting the edges.

15. An assembly as set forth in claim 14 wherein said controller (28) includes a storage parcel (46) for establishing a reference image level of the analog signals (26) representing a non-moisture (20) condition of the exterior surface (22) of the glass (14), for scanning the analog signals (26), for producing a wiper signal (30) in response to a deviation from the reference image level, and for changing the reference image level in response to permanent changes in the non-moisture (20) condition of the exterior surface (22) of the glass (14).

16. An assembly as set forth in claim 11 wherein said controller (28) includes an edge detector (40) for detecting the edges in the first and second images.