Position detection apparatus including a circuit for receiving a plurality of output signal values and fitting the output signal values to a curve
First Claim
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1. Apparatus for determining a position of a member movable along a defined path, comprising:
- means for producing a magnetic field attached to said member;
an array of magnetic field transducers located adjacent said defined path, each transducer comprising magnetoresistive material and providing a bipolar output signal as said means for producing a magnetic field approaches, passes and moves away from said each transducer, with said magnetic field of sufficient strength to saturate said magnetoresistive material;
said array of transducers providing a plurality of output signal values for a first position of said means for producing a magnetic field; and
electronic means for receiving said plurality of output signal values and fitting said plurality of output signal values to a first curve and using a crossover point of said first curve to determine said first position.
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Abstract
A member having a magnet attached is moveable along a path which has an array of magnetic field sensors adjacent the path. Each sensor provides a bipolar output signal as the magnet passes. A plurality of sensors provide a plurality of output signals for a first position of the magnet. Electronic means fit the plurality of output signals to a first curve having a crossover point to determine the first position.
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Citations
15 Claims
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1. Apparatus for determining a position of a member movable along a defined path, comprising:
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means for producing a magnetic field attached to said member; an array of magnetic field transducers located adjacent said defined path, each transducer comprising magnetoresistive material and providing a bipolar output signal as said means for producing a magnetic field approaches, passes and moves away from said each transducer, with said magnetic field of sufficient strength to saturate said magnetoresistive material; said array of transducers providing a plurality of output signal values for a first position of said means for producing a magnetic field; and electronic means for receiving said plurality of output signal values and fitting said plurality of output signal values to a first curve and using a crossover point of said first curve to determine said first position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for determining a position of a movable member of a valve, said movable member controlled by an actuator and movable along a path, said apparatus comprising:
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a magnet attached to said movable member for producing a magnetic field, said magnetic field having components lying along an x axis, a y axis and a z axis, said x axis, said y axis and said z axis being mutually perpendicular; an array of magnetic field transducers located adjacent said path, each said transducer comprising magnetoresistive material and being sensitive to magnetic field components lying along at least one of said x-axis, said y-axis or said z-axis, each transducer providing a bipolar output signal as said magnet moves toward, passes and moves away from said each transducer, with said magnetic field being of sufficient strength to magnetically saturate said magnetoresistive material; said array of transducers providing a plurality of output signal values for a first position of said magnet; and electronic means for receiving said plurality of output signal values and fitting said plurality of output signal values to a first curve and using a crossover to determine said position. - View Dependent Claims (10, 11, 12)
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13. Apparatus for determining a position of a member movable along a defined path, comprising:
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a dipole magnet attached to said member; an array of magnetic field transducers comprising magnetoresistive material located adjacent said defined path, each transducer providing a bipolar output signal as said magnet moves toward, passes and moves away from said each transducer, with said magnet providing a sufficient magnetic field to cause said magnetoresistive material to be magnetically saturated; said array of transducers providing a plurality of output signal values for a first position of said magnet; and electronic means for receiving said plurality of output signal values and fitting said plurality of output signal values to a first curve and using a crossover point of said first curve to determine said first position. - View Dependent Claims (14)
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15. A method for determining a position of a member movable along a defined path, comprising the following steps:
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providing a means for producing a magnetic field attached to said member; providing an array of magnetoresistive magnetic field transducers adjacent said defined path; determining a characteristic curve for a magnetoresistive magnetic field transducer as said magnet approaches, passes and moves away from said transducer with said transducer being magnetically saturated; determining a plurality of output values from a plurality of transducers for a first position of said means for producing a magnetic field; and fitting said plurality of output values to said characteristic curve to determine said first position.
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Specification