Tuning fork gyroscope
First Claim
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1. A tuning fork gyroscope comprising:
- a first substrate;
a plurality of proof masses including at least first and second proof masses suspended with respect to the first substrate;
means for oscillating the proof masses along a drive axis in the direction of the plane of the first substrate;
at least first and second sense plates supported by the first substrate, the first sense plate disposed under the first proof mass defining a first nominal gap between the first proof mass and the first sense plate, the second sense plate disposed under the second proof mass defining a second nominal gap between the second proof mass and the second sense plate;
a second substrate spaced from the first substrate;
at least third and fourth sense plates supported by the second substrate, the third sense plate disposed over the first proof mass defining a third nominal gap between the first proof mass and the third sense plate, the fourth sense plate disposed over the second proof mass defining a fourth nominal gap between the second proof mass and the fourth sense plate; and
means for sensing changes in the first, second, third and fourth nominal gaps between each sense plate and each proof mass and for outputting a signal indicative of the gyroscope angular rate about an axis parallel to the substrates.
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Abstract
A tuning fork gyroscope typically including at least one proof mass with an upper sense plate disposed above the proof mass and a lower sense plate disposed below the proof mass and means for sensing changes in the nominal gaps between the sense plate and the proof mass and for outputting a signal indicative of the gyroscope angular rate.
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Citations
74 Claims
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1. A tuning fork gyroscope comprising:
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a first substrate;
a plurality of proof masses including at least first and second proof masses suspended with respect to the first substrate;
means for oscillating the proof masses along a drive axis in the direction of the plane of the first substrate;
at least first and second sense plates supported by the first substrate, the first sense plate disposed under the first proof mass defining a first nominal gap between the first proof mass and the first sense plate, the second sense plate disposed under the second proof mass defining a second nominal gap between the second proof mass and the second sense plate;
a second substrate spaced from the first substrate;
at least third and fourth sense plates supported by the second substrate, the third sense plate disposed over the first proof mass defining a third nominal gap between the first proof mass and the third sense plate, the fourth sense plate disposed over the second proof mass defining a fourth nominal gap between the second proof mass and the fourth sense plate; and
means for sensing changes in the first, second, third and fourth nominal gaps between each sense plate and each proof mass and for outputting a signal indicative of the gyroscope angular rate about an axis parallel to the substrates. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method for reducing errors in a tuning fork gyroscope comprising:
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determining a first distance, gt, between an upper sense plate and a proof mass and a second distance, gb, between a lower sense plate and the proof mass; and
applying a first voltage, Vt, to the upper sense plate and a second voltage, Vb, to the lower sense plate, wherein the ratio of the first voltage and the second voltage, is a function of the first distance and the second distance. - View Dependent Claims (32, 33, 34, 35, 36)
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37. A method for reducing errors in a tuning fork gyroscope including first and second proof masses, a left upper sense plate disposed over the first proof mass, a right upper sense plate disposed over the second proof mass, a left lower sense plate disposed under the first proof mass and a right lower sense plate disposed under the second proof mass, the method comprising:
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measuring a first distance, gtl, between the left upper sense plate and the first proof mass, measuring a second distance, gtr, between the right upper sense plate and the second proof mass, measuring a third distance, gbl, between the left lower sense plate and the first proof mass, and measuring a fourth distance, gbr, between the right lower sense plate and the second proof mass; and
applying a first voltage, Vtl, to the left upper sense plate, a second voltage, Vtr, to the right upper sense plate, a third voltage, Vbl, to the left lower sense plate, and a fourth voltage, Vbr, to the lower right sense plate, wherein the ratio of Vtl and Vbl is a function of gtl and gbl and the ratio of Vtr and Vbr is a function of gtr and gbr. - View Dependent Claims (38, 39)
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40. A tuning fork gyroscope comprising:
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a first substrate;
at least a first proof mass suspended with respect to the first substrate;
means for oscillating the first proof mass along a drive axis in the direction of the plane of the first substrate;
at least a first sense plate supported by the first substrate, the first sense plate disposed under the first proof mass defining a first nominal gap between the first proof mass and the first sense plate, a second substrate spaced from the first substrate;
at least a second sense plate supported by the second substrate, the second sense plate disposed over the first proof mass defining a second nominal gap between the first proof mass and the second sense plate; and
means for sensing changes in the first and second nominal gaps between each sense plate and the first proof mass and for outputting a signal indicative of angular displacement of the gyroscope. - View Dependent Claims (41, 42, 43, 44)
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45. A method for fabricating a tuning fork gyroscope with upper and lower sense plates, the method comprising:
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providing a silicon substrate;
etching the silicon substrate to provide at least one recess in the silicon substrate;
producing a structure layer having a predetermined thickness;
etching the structure layer to provide at least one proof mass;
applying a metal coating to the silicon substrate beneath a portion of each proof mass;
providing a glass substrate;
etching the glass substrate to provide at least one recess in the glass substrate;
depositing a multimetal layer to the at least one recess;
electrostatically bonding the silicon substrate to the glass substrate; and
etching the silicon substrate down to the structure layer. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62)
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63. A tuning fork gyroscope comprising:
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a first substrate;
a plurality of proof masses including at least first and second proof masses suspended with respect to the first substrate;
means for oscillating the proof masses along a drive axis in the direction of the plane of the first substrate;
at least first and second sense plates supported by the first substrate, the first sense plate disposed adjacent the first proof mass defining a first nominal gap between the first proof mass and the first sense plate, the second sense plate disposed adjacent the second proof mass defining a second nominal gap between the second proof mass and the second sense plate;
a second substrate spaced from the first substrate;
at least third and fourth sense plates supported by the second substrate, the third sense plate disposed adjacent the first proof mass but opposite the first sense plate, defining a third nominal gap between the first proof mass and the third sense plate, the fourth sense plate disposed adjacent the second proof mass but opposite the second sense plate, defining a fourth nominal gap between the second proof mass and the fourth sense plate; and
means for sensing changes in the first, second, third and fourth nominal gaps between each sense plate and each proof mass and for outputting a signal indicative of the gyroscope angular rate about an axis perpendicular to the substrates. - View Dependent Claims (64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74)
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Specification