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Lens system for moisture sensor device

  • US 5,278,425 A
  • Filed: 01/19/1993
  • Issued: 01/11/1994
  • Est. Priority Date: 01/23/1992
  • Status: Expired due to Term
First Claim
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1. A sensor device for detecting the degree of wetting of a transparent windscreen by drop-shaped precipitation which lies on an outer surface thereof, the sensor device comprising:

  • a beam transmitter located proximate an inner surface of the windscreen, a beam receiver in optical communication with the transmitter, and a beam guide element positioned therebetween, the guide element being affixed to an inner surface of the windscreen and having two trapezoidal faces oriented orthogonally to each other, each face being provided with an aspherical lens which is associated with the beam transmitter or receiver;

    the beam transmitter, receiver and guide element being positioned so that rays emitted by the beam transmitter pass through the guide element before and after reflection by the windscreen with an intensity which is a function of the precipitation on the windscreen;

    the receiver supplying a signal to a control unit and thence to a motor-operated windscreen wiping device in response to the quantity of precipitation;

    the lenses (IIb) being spaced apart from the associated transmitter (III) or receiver and including a lens surface (IIb") facing the transmitter (III) or receiver;

    each lens surface (IIb") being at least partially configured according to a polynomial of or greater than the third degree and being developed to form a body of rotation.

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