Multiple servo loop accelerometer with tunnel current sensors
First Claim
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1. An accelerometer having a proof mass coupled to a frame with a highly compliant suspension, said accelerometer comprising:
- first and second tunnel current sensors disposed on opposite sides of a normal axis which is normal to an input axis of said accelerometer and aligned on a further axis which is perpendicular to said normal axis and normal to said input axis, each of said first and second tunnel current [sensor]sensors having a first sensing electrode disposed in substantially fixed relation to said frame and a second sensing electrode disposed on said proof mass in close proximity to said first sensing electrode;
A first pair of drive electrodes disposed proximate said first tunnel current sensor; and
a second pair of drive electrodes disposed proximate said second tunnel current sensor, said first and second pair of drive electrodes disposed on opposite sides of said normal axis to control undesired movement of said proof mass about said normal axis.
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Abstract
A servo accelerometer permits compliant suspension with a pair of flexures by using a plurality of tunnel current position sensors each respectively associated with a corresponding pair of electrostatic drive electrodes. The tunnel current position sensors and the electrostatic drive electrodes are positioned to control undesired movement of the proof mass about a first axis which is normal to the input axis of the accelerometer. In another embodiment, three tunnel current sensors and three pairs of drive electrodes are used to control movement of the proof mass about the first axis and a second axis.
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Citations
9 Claims
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1. An accelerometer having a proof mass coupled to a frame with a highly compliant suspension, said accelerometer comprising:
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first and second tunnel current sensors disposed on opposite sides of a normal axis which is normal to an input axis of said accelerometer and aligned on a further axis which is perpendicular to said normal axis and normal to said input axis, each of said first and second tunnel current [sensor]sensors having a first sensing electrode disposed in substantially fixed relation to said frame and a second sensing electrode disposed on said proof mass in close proximity to said first sensing electrode; A first pair of drive electrodes disposed proximate said first tunnel current sensor; and a second pair of drive electrodes disposed proximate said second tunnel current sensor, said first and second pair of drive electrodes disposed on opposite sides of said normal axis to control undesired movement of said proof mass about said normal axis. - View Dependent Claims (2, 3, 4)
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5. An accelerometer having a proof mass coupled to a frame with a highly compliant suspension, said accelerometer comprising:
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first and second tunnel current sensors disposed on opposite sides of a first axis which is normal to an input axis of said accelerometer; a third tunnel current sensor, said second and third tunnel current sensors disposed on opposite sides of a second axis which is perpendicular to said first axis and normal to said input axis, each of the first, second and third tunnel current sensors having a first sensing electrode disposed in substantially fixed relation to said frame and a second sensing electrode disposed on said proof mass in close proximity to said first sensing electrode; a first pair of drive electrodes disposed proximate said first tunnel current sensor; a second pair of drive electrodes disposed proximate said second tunnel current sensor; and a third pair of drive electrodes disposed proximate said third tunnel current sensor, said first and second pair of drive electrodes disposed on opposite sides of said first axis and said second and third pair of drive electrodes disposed on opposite sides of said second axis so as to control undesired movement of said proof mass about said first and second axes. - View Dependent Claims (6, 7, 8)
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9. An accelerometer having a proof mass coupled to a frame with a highly compliant suspension, said accelerometer comprising:
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first and second tunnel current sensors disposed on opposite sides of a normal axis which is normal to an input axis of said accelerometer, and aligned on a further axis which is perpendicular to said normal axis and normal to said input axis, each of said first and second tunnel current sensors having a first sensing electrode disposed in substantially fixed relation to said frame and a second sensing electrode disposed on said proof mass in close proximity to said first sensing electrode; a first pair of drive electrodes disposed proximate said first tunnel current sensor; and a second pair of drive electrodes disposed proximate said second tunnel current sensor, said first and second pair of drive electrodes disposed on opposite sides of said normal axis equidistant from said normal axis to control undesired movement of said proof mass about said normal axis.
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Specification