Anchor-tilt cancelling accelerometer
First Claim
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1. An accelerometer, comprising:
- a mechanical structure, comprising;
a substrate;
an anchor coupled to the substrate;
a first proof mass coupled to the anchor by a first flexible member wherein the first proof mass rotates in response to an acceleration of the accelerometer about a first axis; and
a second proof mass coupled to the anchor by a second flexible member, wherein the second proof mass rotates in response to the acceleration of the accelerometer about a second axis, wherein the first and second axes are co-linear;
a first transducer configured to measure a first distance between a first reference area and a first portion of the first proof mass;
a second transducer configured to measure a second distance between a second reference area and a second portion of the first proof mass;
a third transducer configured to measure a third distance between a third reference area and a first portion of the second proof mass;
a fourth transducer configured to measure a fourth distance between a fourth reference area and a second portion of the second proof mass; and
a signal processing circuit coupled to the first transducer, the second transducer the third transducer, and the fourth transducer, the signal processing circuit configured to provide an output related to the acceleration,wherein the first and second flexible members provide torsional compliance about the first axis.
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Abstract
Described herein is an accelerometer that can be sensitive to acceleration, but not anchor motion due to sources other than acceleration. The accelerometer can employ a set of electrodes and/or transducers that can register motion of the proof mass and support structure and employ and output-cancelling mechanism so that the accelerometer can distinguish between acceleration and anchor motion due to sources other than acceleration. For example, the effects of anchor motion can be cancelled from an output signal of the accelerometer so that the accelerometer exhibits sensitivity to only acceleration.
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Citations
19 Claims
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1. An accelerometer, comprising:
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a mechanical structure, comprising; a substrate; an anchor coupled to the substrate; a first proof mass coupled to the anchor by a first flexible member wherein the first proof mass rotates in response to an acceleration of the accelerometer about a first axis; and a second proof mass coupled to the anchor by a second flexible member, wherein the second proof mass rotates in response to the acceleration of the accelerometer about a second axis, wherein the first and second axes are co-linear; a first transducer configured to measure a first distance between a first reference area and a first portion of the first proof mass; a second transducer configured to measure a second distance between a second reference area and a second portion of the first proof mass; a third transducer configured to measure a third distance between a third reference area and a first portion of the second proof mass; a fourth transducer configured to measure a fourth distance between a fourth reference area and a second portion of the second proof mass; and a signal processing circuit coupled to the first transducer, the second transducer the third transducer, and the fourth transducer, the signal processing circuit configured to provide an output related to the acceleration, wherein the first and second flexible members provide torsional compliance about the first axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An accelerometer, comprising:
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a mechanical structure, comprising; a substrate; an anchor coupled to the substrate; a first proof mass coupled to the anchor by a first flexible member, wherein a force applied to the anchor causes anchor motion and in response to the anchor motion, the first proof mass rotates relative to the substrate; a second proof mass coupled to the anchor by a second flexible member that rotates in response to the anchor motion relative to the substrate, wherein the first and second proof masses are aligned about a first axis; a first transducer configured to measure a first distance between a first reference area and a first portion of the first proof mass; a second transducer configured to measure a second distance between a second reference area and a second portion of the first proof mass; a third transducer configured to measure a third distance between a third reference area and a first portion of the second proof mass; a fourth transducer configured to measure a fourth distance between a fourth reference area and a second portion of the second proof mass; and a signal processing circuit coupled to the first transducer, the second transducer the third transducer, and the fourth transducer, the signal processing circuit configured to measure the anchor motion, wherein the signal processing circuit produces a first signal proportional to the difference of an output of the first and second transducers and a second signal proportional to the difference of an output of the third and fourth transducers, further wherein the signal processing circuit determines a difference between the first signal and the second signal proportional to the anchor motion of the first and second proof masses, further wherein the first and second flexible members provide torsional compliance about the first axis. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification