Rain sensor using statistical analysis
First Claim
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 rays 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), andsuccessively directing the first and second images from the lens (16) onto a focal plane detector (12),dividing each of the images into a plurality of elements (24),said method characterized by scanning the elements in a first scan and producing an initial reference value for each element in response to an initial image in that element, scanning the elements in a second scan and producing a subsequent value different from the initial reference value in response to an initial image in that element, developing a correlation coefficient value from the reference and subsequent values, and producing a wiper signal in response to the correlation coefficient value deviating from a predetermined value.
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Accused Products
Abstract
A method and an assembly for sensing moisture (20) on the exterior surface (22) of a sheet of glass (14) by positioning an imaging lens (16) adjacent to the interior surface (18) of the sheet of glass (14), passing light rays 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). The focal plane detector (12) is divided into rows of pixels (24) which are ligned into columns. The assembly and method are characterized by scanning the pixels (24) of each row in a first scan (FIG. 4) and producing a reference value X for each pixel (24) in response to an initial image in that pixel (24), scanning the pixels (24) of each row in a second scan (FIG. 5) and producing a subsequent value Y different from the reference value in response to an subsequent image in that pixel (24). A correlation coefficient value r is developed for each row with a statistical formula from the reference and subsequent values to produce a wiper signal in response to the correlation coefficient value r deviating from a predetermined value. An additional condition to the wiper signal could be that the correlation coefficient values r differ from row to row.
398 Citations
14 Claims
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1. A method for sensing moisture (20) on the exterior surface (22) of a sheet of glass (14) comprising the steps of;
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positioning an imaging lens (16) adjacent to the interior surface (18) of the sheet of glass (14), passing light rays 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 each of the images into a plurality of elements (24), said method characterized by scanning the elements in a first scan and producing an initial reference value for each element in response to an initial image in that element, scanning the elements in a second scan and producing a subsequent value different from the initial reference value in response to an initial image in that element, developing a correlation coefficient value from the reference and subsequent values, and producing a wiper signal in response to the correlation coefficient value deviating from a predetermined value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An assembly for sensing moisture (20) on a glass (14) surface from a position adjacent the glass (14), said assembly comprising;
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a focal plane detector (12) adapted for disposition adjacent to the interior surface (18) of the sheet of glass (14), and 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 rays 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), a plurality of pixels (24) for dividing the images into a plurality of elements, said assembly characterized by a controller (28) for scanning the elements in a first scan and producing a reference value for each element in response to an initial image in that element, for scanning the elements in a second scan and producing a subsequent value different from the reference value in response to a subsequent image in that element, for developing a correlation coefficient value from the reference and subsequent values, and for producing a wiper signal in response to the correlation coefficient value deviating from a predetermined value. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification