Compact moisture sensor with collimator lenses and prismatic coupler

  • US 5,661,303 A
  • Filed: 05/24/1996
  • Issued: 08/26/1997
  • Est. Priority Date: 05/24/1996
  • Status: Expired due to Term
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First Claim
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1. A moisture sensor for mounting on a surface of a sheet of glass to detect moisture on an opposite surface of the sheet of glass, said moisture sensor comprising:

  • a) a coupler for mounting on an inner surface of a sheet of glass, said coupler including a pair of prismatic refracting regions in spaced apart relationship;

    b) a housing secured to said coupler;

    c) a planar circuit board secured in said housing and having a device surface which is positioned generally parallel to the inner surface of the sheet of glass;

    d) an emitter mounted on the device surface, said emitter emitting light beams with an optical axis approximately perpendicular to the device surface of said circuit board;

    e) an emitter lens mounted in said housing and positioned between said emitter and a first prismatic region of said coupler, said emitter lens including a reflection surface;

    f) a detector mounted on the device surface for detecting light beams striking the detector at an angle within an acceptance angle of said detector, and for generating control signals in response to the light beams; and

    g) a detector lens having a reflection surface, said detector lens mounted in said housing and positioned between said detector and a second prismatic region of said coupler; and

    said emitter lens, said coupler with prismatic refracting regions, and said detector lens positioned to form an optical path from said emitter to an outer surface of said glass, and back to said detector such that the light beams are emitted at an angle approximately perpendicular to said circuit board, are directed into and reflected from the sheet of glass at an angle between forty and fifty degrees, and are received at the detector at an angle within the acceptance angle of said detector.

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