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Remote level sensing instrument

  • US 4,154,000 A
  • Filed: 07/19/1977
  • Issued: 05/15/1979
  • Est. Priority Date: 01/12/1976
  • Status: Expired due to Term
First Claim
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1. Apparatus for sensing orientation of a remote surface with respect to level comprising:

  • an elongated transparent vial enclosing a fluid and a bubble, said vial being formed along the length thereof as a segment of an arc,a portable housing means for establishing a reference line parallel to the surface to be sensed, said housing further including means mounting said vial therein with the elongated axis of said vial and said reference line defining a plane perpendicular to the surface to be sensed, said mounting means positioning said vial with the central portion of said arc higher than the ends of said vial when vial is level,a plurality of light beam channels within said housing and each including means for directing a concentrated column of light against one sidewall of said vial so that said light column will pass through the vial and said fluid and will exit from the sidewall of said vial at a second point along an arc defined by the cross-section of said vial, each said column of light exiting in a first direction after passing through said bubble and in a second direction after passing through said fluid, said light beam channels being arcuately arranged along said vial and spanning a distance greater than the length of said bubble, two of said light beam channels of said plurality being directed towards said one sidewall in proximity to but spaced from respective ends of said bubble when said vial is level, said plurality of light beam channels each further including a light sensitive device responsive to a light column from one of said exit directions while being isolated from light emanating from any other direction so that the electrical conductivity state of each said light sensitive device reflects the position of said bubble within the said vial,circuit means responsive to the electrical conductivity states of said light sensitive devices for generating first and second output signals representing the direction and magnitude of displacement of said vial relative to the level attitude of said reference line, andoverrange detector means responsive to the electrical conductivity states of said light sensitive devices associated with said two of said light beam channels for generating an output signal when said bubble is out of the detectable range of the other of said plurality of light beam channels.

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