Optoelectronic sensor for detecting moisture on a windshield with means to compensate for a metallic layer in the windshield

  • US 5,498,866 A
  • Filed: 02/10/1994
  • Issued: 03/12/1996
  • Est. Priority Date: 06/01/1993
  • Status: Expired due to Fees
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First Claim
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1. An optoelectronic sensor device for detecting the degree of wetting of a multi-layer transparent pane by drop-shaped precipitation, the sensor device comprising:

  • a beam guide element having a front surface connected to an inner surface of the pane not exposed to the precipitation in a region of a wiping area covered by a motor driven windscreen wiper device, the beam guide element having at least one measuring path with a beam entry window and first and second beam exit windows;

    a beam transmitter associated with the beam entry window;

    a first beam detector associated with the first beam exit window in such a manner that beams emitted by the beam transmitter are reflected in dependence upon the precipitation present on the pane and directed to the first beam detector, which provides a first signal dependent upon the associated quantity of precipitation;

    a second beam detector associated with the second beam exit window in such a manner that only spurious beams reflected at a partially transparent metallic intermediate layer located in the pane are detected by the second beam detector, which provides a second signal representative of a quantity of the spurious beams; and

    compensating means for correcting the first signal supplied by the first beam detector and representative of a quantity of mixed beams including useful beams and spurious beams, the correction being dependent upon the second signal supplied by the second beam detector.

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