Angular rate sensor having multiple axis sensing capability
First Claim
1. An angular rate sensor comprising:
- a substrate having a surface;
a drive mass flexibly coupled to said substrate, said drive mass being configured to move with an oscillatory rotary drive motion about a first axis that is substantially perpendicular to said surface of said substrate, said drive mass having a central opening defined by an inner perimeter;
a coupler element located in said central opening and suspended above said surface of said substrate;
a first sense mass located in said central opening and interconnected between said inner perimeter of said drive mass and said coupler element via first spring elements;
a second sense mass located in said central opening and interconnected between said inner perimeter of said drive mass and said coupler element via second spring elements, said first and second sense masses being positioned on opposing sides of a second axis with said coupler element located between said first and second sense masses, said second axis being oriented substantially parallel to said surface of said substrate, wherein said oscillatory rotary drive motion of said drive mass imparts a linear drive motion on said first and second sense masses via said first and second spring elements, said linear drive motion being in a first drive direction substantially parallel to said second axis.
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Abstract
An angular rate sensor (20) includes a single drive mass (24) and distributed sense masses (36, 38, 40, 42) located within a central opening (30) of the drive mass (24). The drive mass (24) is enabled to rotate around the Z-axis (64) under electrostatic stimulus. The sense masses (36, 38, 40, 42) are coupled to the drive mass by spring elements (44, 46, 48, 50) such that oscillatory rotary motion (90) of the drive mass imparts a linear drive motion (92, 94) on the sense masses. The distributed sense masses form two pairs of sense masses, where one pair senses X- and Z-axis angular rate and the other pair senses Y- and Z-axis angular rate. The sense masses are coupled to one another via a centrally located coupler element (34) to ensure that the sense masses of each pair are moving in anti-phase.
46 Citations
20 Claims
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1. An angular rate sensor comprising:
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a substrate having a surface; a drive mass flexibly coupled to said substrate, said drive mass being configured to move with an oscillatory rotary drive motion about a first axis that is substantially perpendicular to said surface of said substrate, said drive mass having a central opening defined by an inner perimeter; a coupler element located in said central opening and suspended above said surface of said substrate; a first sense mass located in said central opening and interconnected between said inner perimeter of said drive mass and said coupler element via first spring elements; a second sense mass located in said central opening and interconnected between said inner perimeter of said drive mass and said coupler element via second spring elements, said first and second sense masses being positioned on opposing sides of a second axis with said coupler element located between said first and second sense masses, said second axis being oriented substantially parallel to said surface of said substrate, wherein said oscillatory rotary drive motion of said drive mass imparts a linear drive motion on said first and second sense masses via said first and second spring elements, said linear drive motion being in a first drive direction substantially parallel to said second axis. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of fabricating a microelectromechanical systems (MEMS) angular rate sensor comprising:
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forming a drive mass flexibly coupled to a substrate and enabled to move with an oscillatory rotary drive motion about a first axis that is substantially perpendicular to a surface of said substrate, said drive mass including a central opening defined by an inner perimeter; forming a coupler element in said central opening and suspended above said surface of said substrate; forming a first sense mass, a second sense mass, a third sense mass, and a fourth sense mass in said central opening; forming first spring elements between said first sense mass and said inner perimeter of said drive mass and between said first sense mass and said coupler element; forming second spring elements between said second sense mass and said inner perimeter of said drive mass and between said second sense mass and said coupler element, said first and second sense masses being positioned on opposing sides of a second axis with said coupler element located between said first and second sense masses, said second axis being oriented substantially parallel to said surface of said substrate, said first and second sense masses being enabled to undergo a linear drive motion via said first and second spring elements in response to said oscillatory rotary drive motion, said linear drive motion being in a first drive direction substantially parallel to said second axis; forming third spring elements between said third sense mass and said inner perimeter of said drive mass and between said third sense mass and said coupler element; forming fourth spring elements between said fourth sense mass and said inner perimeter of said drive mass and between said fourth sense mass and said coupler element, said third and fourth sense masses being positioned on opposing sides of a third axis with said coupler element located between said third and fourth sense masses, said third axis being oriented substantially parallel to said surface of said substrate and perpendicular to said second axis, said third and fourth sense masses being enabled to undergo said linear drive motion via said third and fourth spring elements in response to said oscillatory rotary drive motion, said linear drive motion being imparted on said third and fourth drive masses in a second drive direction substantially parallel to said third axis. - View Dependent Claims (15, 16)
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17. An angular rate sensor comprising:
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a substrate having a surface; a drive mass flexibly coupled to said substrate, said drive mass being configured to move with an oscillatory rotary drive motion about a first axis that is substantially perpendicular to said surface of said substrate, said drive mass having a central opening defined by an inner perimeter; a coupler element located in said central opening and suspended above said surface of said substrate; a first sense mass located in said central opening and interconnected between said inner perimeter of said drive mass and said coupler element via first spring elements; a second sense mass located in said central opening and interconnected between said inner perimeter of said drive mass and said coupler element via second spring elements, said first and second sense masses being positioned on opposing sides of a second axis with said coupler element located between said first and second sense masses, said second axis being oriented substantially parallel to said surface of said substrate; first electrodes disposed on said surface of said substrate beneath each of said first and second sense masses; first fixed electrodes anchored to said substrate and first movable electrodes extending from edges of said first and second sense masses, said first movable electrodes being positioned proximate said first fixed electrodes, said first fixed electrodes and first movable electrodes being longitudinally aligned with said second axis;
whereinsaid oscillatory rotary drive motion of said drive mass imparts a linear drive motion on said first and second sense masses via said first and second spring elements, said linear drive motion being in a first drive direction substantially parallel to said second axis; said first and second spring elements enable said first and second sense masses to oscillate relative to a first sense axis in response to an angular velocity about a first input axis, said first sense axis being substantially perpendicular to said surface of said substrate, and said first input axis being substantially parallel to said surface of said substrate and substantially perpendicular to said second axis; and said first and second spring elements enable said first and second sense masses to oscillate relative to a second sense axis in response to said angular velocity about a second input axis, said second sense axis being substantially parallel to said surface of said substrate, and said second input axis being substantially perpendicular to said surface of said substrate. - View Dependent Claims (18, 19, 20)
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Specification