Miniature magnetometer-accelerometer
First Claim
Patent Images
1. An integrated magnetometer and accelerometer device, comprising:
- a pendulum mounted to move in response to an acceleration of the device;
a conductor attached to said pendulum for conducting an ac current so as to move said pendulum in reaction to a magnetic field that is to be sensed; and
a transducer for producing output signals representing combined acceleration and magnetic field movement of said pendulum;
drive means for driving said transducer; and
signal processing means for processing said output signals.
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Abstract
A magnetometer is integrated with a miniature vibrating beam accelerometer fabricated out of silicon on a common substrate. Dual pendulum-DETF force sensing accelerometers have integrated conductor coils on the pendulums that circulate alternating current to cause an additional pendulum motion also sensed by the DETF transducers for sensing local earth magnetic field. The integrated magnetic and acceleration sensing is used for each of three reference axes in a triaxial inclinometer magnetometer for borehole drill steering and surveying.
68 Citations
14 Claims
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1. An integrated magnetometer and accelerometer device, comprising:
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a pendulum mounted to move in response to an acceleration of the device; a conductor attached to said pendulum for conducting an ac current so as to move said pendulum in reaction to a magnetic field that is to be sensed; and a transducer for producing output signals representing combined acceleration and magnetic field movement of said pendulum; drive means for driving said transducer; and signal processing means for processing said output signals. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A borehole device for use in determining the heading and position of downhole equipment comprising:
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(a) accelerometer means including a pendulum responsive to acceleration to cause a first movement of the pendulum for generating an output signal relating the orientation of the device to true vertical; (b) magnetometer means integrated with said accelerometer means for generating an output signal relating azimuth of the device to a magnetic North reference including a current conducting coil supported by said pendulum for interacting with local earth magnetic field to cause a second movement of the pendulum; (c) transducer means for converting the first and second movements of said pendulum into output signals; and (d) signal processing means for determining inclination and magnetic azimuth of the device in response to the output signals from said transducer means. - View Dependent Claims (9)
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10. An integrated magnetometer and inclinometer, comprising a plurality of detection modules, one for each of a plurality of axes, each module comprising:
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a pendulum mounted to respond to acceleration along one of the axes that is to be sensed; a conductor attached to the pendulum and drive circuit means for causing a current to flow in said conductor for interacting with a local earth magnetic field along one of the axes that is to be sensed for imparting movement to the pendulum in reaction to the strength and direction of local earth magnetic field; a force to electrical signal transducer for producing an output representing combined acceleration and earth magnetic field measurements along the associated axes in reaction to movement of said pendulum; and a sisal processor for processing said output of said transducer. - View Dependent Claims (11, 12, 13, 14)
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Specification