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Water drop detector on transparent substrate

  • US 5,998,782 A
  • Filed: 11/13/1998
  • Issued: 12/07/1999
  • Est. Priority Date: 11/14/1997
  • Status: Expired due to Fees
First Claim
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1. A water drop detector on a transparent substrate having the function of detecting the presence of liquid water upon one side surface of the transparent substrate depending upon variations in an amount of reflected light, comprising:

  • a sensor device provided at the other surface side of said transparent substrate, the sensor further comprising;

    light emitting means for guiding light into said transparent substrate;

    light receiving means for detecting the light which is reflected within said transparent substrate; and

    light shielding members provided at the other surface side of said transparent substrate opposing said light emitting means and said light receiving means, respectively;

    whereinone of the light shielding members shields the light emitted from said light emitting means at an incident angle less than a critical angle at which total internal reflection occurs upon a boundary surface between ambient air and said transparent substrate, while the other of said light shielding members shields ambient light incident upon said light receiving means.

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