Micromachined rate and acceleration sensor
First Claim
1. Apparatus for measuring the specific force and angular rotation rate of a moving body, comprising:
- a) an accelerometer having a force sensing axis for producing a first output signal indicative of the acceleration of the moving body along said force sensing axis;
b) mounting means for mounting said accelerometer such that said accelerometer can be moved along a dither axis perpendicular to said force sensing axis, said mounting means having at least one support surface;
c) signal generator means for producing a periodic drive signal having a predetermined frequency; and
d) drive means responsive to said drive signal for imparting a dithering motion to said accelerometer along said dither axis at said predetermined frequency, said drive means comprising a conductive path formed on said support surface and connected to said signal generator means to receive said drive signal therethrough, and means for directing a magnetic flux to cross said conductive path, whereby the interaction of said magnetic flux and drive signal passing through said conductive path causes said accelerometer to vibrate along said dither axis.
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Accused Products
Abstract
A sensor (10) is disclosed for measuring the specific force and angular rotation rate of a moving body and is micromachined from a silicon substrate (16). First and second accelerometers (32a and b) are micromachined from the silicon substrate (16), each having a force sensing axis (38) and producing an output signal of the acceleration of the moving body along its force sensing axis (38). The first and second accelerometers (32a and b) are mounted within the substrate (16) to be moved along a vibration axis (41). The first and second accelerometers (32a and b) are vibrated or dithered to increase the Coriolis component of the output signals from the first and second accelerometers (32a and b). A sinusoidal drive signal of a predetermined frequency is applied to a conductive path (92) disposed on each of the accelerometers. Further, magnetic flux is directed to cross each of the conductive paths (92), whereby the interaction of the magnetic flux and of the drive signal passing therethrough causes the desired dithering motion. A link (72) is formed within the silicon substrate (16) and connected to each of the accelerometers (32a and b), whereby motion imparted to one results in a like, but opposite motion applied to the other accelerometer (32). Further, a unitary magnet (20) and its associated flux path assembly direct and focus the magnetic flux through the first and second accelerometers (32a and b) formed within the silicon substrate (16).
189 Citations
19 Claims
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1. Apparatus for measuring the specific force and angular rotation rate of a moving body, comprising:
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a) an accelerometer having a force sensing axis for producing a first output signal indicative of the acceleration of the moving body along said force sensing axis; b) mounting means for mounting said accelerometer such that said accelerometer can be moved along a dither axis perpendicular to said force sensing axis, said mounting means having at least one support surface; c) signal generator means for producing a periodic drive signal having a predetermined frequency; and d) drive means responsive to said drive signal for imparting a dithering motion to said accelerometer along said dither axis at said predetermined frequency, said drive means comprising a conductive path formed on said support surface and connected to said signal generator means to receive said drive signal therethrough, and means for directing a magnetic flux to cross said conductive path, whereby the interaction of said magnetic flux and drive signal passing through said conductive path causes said accelerometer to vibrate along said dither axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for measuring the specific force and angular rotation rate of a moving body, comprising:
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a) a silicon substrate having first and second substantially planar surfaces disposed substantially parallel to each other; b) an accelerometer formed of said substrate and having a force sensing axis for producing an output signal indicative of the acceleration of the moving body along said force sensing axis; c) mounting means formed of said substrate for mounting said accelerometer such that said accelerometer can be moved along a dither axis perpendicular to said force sensing axis, said mounting means having a first conductive path disposed on one of said first and second surfaces; d) said accelerometer comprising a force transducer, which includes a beam having a longitudinal axis, said longitudinal axis disposed perpendicular to said force sensing axis and said dither axis and a second conductive path disposed on one of said first and second surfaces to lie along said longitudinal axis; e) first signal generator means for producing and applying a first periodic drive signal having a predetermined frequency to said first conductive path; f) second signal generator means for producing and applying a second periodic drive signal to said second conductive path, said second periodic drive signal having a resonant frequency that is a function of the force applied along said force sensing axis; and g) common magnetic flux producing means for producing and directing a magnetic flux to cross said first and second conductive paths, whereby the interaction of said magnetic flux and said first drive signal passing through said first conductive path cause said accelerometer to vibrate along said dither axis at said predetermined frequency and the interaction of said magnetic flux and second drive signal passing through said conductive path causes said beam to vibrate at said resonant frequency. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. Apparatus for measuring the specific force and angular rotation rate of a moving body, comprising:
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a) a silicon substrate having first and second substantially planar surfaces disposed substantially parallel to each other; b) a first accelerometer formed of said substrate for producing a first output signal indicative of the acceleration applied to the moving body; c) a second accelerometer formed of said substrate for producing a second output signal indicative of the acceleration applied to the moving body; d) mounting means formed of said substrate for mounting said first and second accelerometers to be moved along a vibration axis substantially parallel to said first and second planar surfaces; and e) drive means coupled to each of said first and second accelerometers for imparting a dithering motion thereto of a predetermined frequency along said vibration axis, said drive means comprising a first conductive path disposed on one of said first and second planar surfaces along a first portion of said mounting means, a second conductive path disposed on one of said first and second substantially planar surfaces along a second portion of said mounting means, a unitary magnet for emanating flux from first and second surfaces thereof, and a pole piece having a first surface adjacent said first surface of said unitary magnet and first and second projections having respectively second and third surfaces adjacent said first substantially planar surface of said silicon substrate, said second and third projection surfaces being of reduced area compared to said first surface of said pole piece and being aligned with said portions of said mounting means, whereby said flux density is increased and is restricted to flow through said portions of said mounting means. - View Dependent Claims (17, 18, 19)
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Specification