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Angular rate and position transducer for borehole survey instrument

  • US 4,459,759 A
  • Filed: 08/04/1982
  • Issued: 07/17/1984
  • Est. Priority Date: 08/04/1982
  • Status: Expired due to Fees
First Claim
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1. A transducer for sensing the angular position of a borehole survey instrument housing with respect to a reference position, comprising:

  • a rotor;

    a stator secured to the housing;

    means for magnetically suspending the rotor within the stator whereby the rotor is constrained to rotate about a single axis relative to the stator;

    means for sensing movement of the rotor about the axis of rotation to develop an indication of the angular position of the housing, the sensing means including a plurality of markings disposed on a face of the rotor and means for optically sensing the markings on the rotor, the optical sensing means comprising a light-emitting diode for illuminating a portion of the markings, a photodetector for sensing an illuminated marking and a second photodetector mounted on the stator with the light-emitting diode and the first photodetector and having a field of view displaced from the field of view of the first photodetector by one-half the width of a marking, the photodetectors generating a pulse when a marking is in its field of view; and

    means for detecting the output of the photodetectors to develop an output signal representing the angular position of the housing relative to the reference position including means for gating the pulses from the photodetectors to develop clock pulses, means for counting the clock pulses to develop the output signal, and means for developing a control signal representing the direction of rotation of the rotor relative to the stator, wherein the clock pulse counting means includes a control input coupled to the control signal developing means causing the clock pulse counting means to increment and decrement the output signal in response to the control signal.

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