Trenches to reduce charging effects and to control out-of-plane sensitivities in tuning fork gyroscopes and other sensors
First Claim
1. A drive for imparting a vibratory force to a vibrating member with a driving member, the vibrating member suspended above a surface of a substrate by a support flexure, comprising:
- first comb electrodes connected to the driving member;
second comb electrodes connected to the vibrating member, said second comb electrodes interleaved with said first comb electrodes, an overlap region defined thereby, a gap being defined between the substrate surface and the interleaved comb electrodes; and
a trench formed in the substrate substantially between the interleaved comb electrodes and the substrate such that the gap between the substrate surface and the interleaved comb electrodes is increased.
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Accused Products
Abstract
Trenches which reduce or eliminate force and sensitivity associated with proof mass motion normal to the substrate as a result of voltage transients is disclosed. The trenches provide increased separation between interleaved comb electrodes and the substrate, and thereby also reduce the comb lift to drive ratio. The trenches are typically formed directly below the interleaved comb electrodes, but may also be formed below other suspended portions. Trench depth is from 6-10 microns and provides a comb electrode to substrate separation of approximately 8.5-12.5 microns.
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Citations
19 Claims
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1. A drive for imparting a vibratory force to a vibrating member with a driving member, the vibrating member suspended above a surface of a substrate by a support flexure, comprising:
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first comb electrodes connected to the driving member; second comb electrodes connected to the vibrating member, said second comb electrodes interleaved with said first comb electrodes, an overlap region defined thereby, a gap being defined between the substrate surface and the interleaved comb electrodes; and a trench formed in the substrate substantially between the interleaved comb electrodes and the substrate such that the gap between the substrate surface and the interleaved comb electrodes is increased. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A tuning fork gyroscope comprising:
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a substrate with a surface; an outer drive with comb electrodes; an inner drive with comb electrodes; proof masses with inner and outer comb electrodes, said proof masses suspended above said substrate by support flexure, said inner comb electrodes interleaved with said inner drive comb electrodes and said outer comb electrodes interleaved with said outer drive comb electrodes, an overlap region defined by said interleaved comb electrodes, a gap being defined between the substrate surface and the interleaved comb electrodes; and trenches formed in said substrate substantially between said inner interleaved comb electrodes and said substrate such that the gap between said substrate surface and said inner interleaved comb electrodes is increased. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. In a tuning fork gyroscope having interleaved comb electrodes defining an overlap region and a substrate surface with a gap defined therebetween, a method for alleviating undesirable effects of substrate voltage transients on gyroscope operation comprising the step of:
increasing the gap between the interleaved comb electrodes and the substrate surface by forming a trench in the substrate substantially between the interleaved comb electrodes and the substrate in the overlap region of the interleaved comb electrodes. - View Dependent Claims (19)
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18. In a tuning fork gyroscope having interleaved comb electrodes and a substrate surface with a gap defined therebetween, and a support flexure, a method for alleviating undesirable effects of substrate voltage transients on gyroscope operation comprising the step of:
increasing the gap between the interleaved comb electrodes and the substrate surface by forming trenches below the interleaved comb electrodes and forming trenches below the support flexure.
Specification