Windshield fog detector

  • US 6,853,897 B2
  • Filed: 01/19/2004
  • Issued: 02/08/2005
  • Est. Priority Date: 10/04/2001
  • Status: Active Grant
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First Claim
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1. A fog detector system for detecting fog on an inside surface of a vehicle window, said fog detector system comprising:

  • an emitter for selectively projecting radiation onto a region of the inside surface of the vehicle window;

    a sensor disposed with its optical axis substantially in parallel with that of said emitter, said sensor being sensitive to the radiation projected by said emitter for sensing levels of incident radiation both when said emitter projects radiation and when said emitter does not project radiation; and

    a control circuit coupled to said emitter for selectively activating said emitter, and coupled to said sensor for receiving signals from said sensor representing the level of incident radiation, said control circuit determines the difference between levels of incident radiation when said emitter is activated and when said emitter is deactivated, and compares the difference to a threshold to determine whether fog is present, said control circuit generates a signal indicating the presence of fog on the vehicle window.

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