Microelectromechanical gyroscope with enhanced rejection of acceleration noises

• US 9,278,847 B2
• Filed: 09/25/2013
• Issued: 03/08/2016
• Est. Priority Date: 12/23/2008
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Cazzaniga, Gabriele, Coronato, Luca, Calcaterra, Giacomo
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US14/037,163
• Publication Number:
  US 20140021564A1
• Time in Patent Office: 895 Days
• Field of Search: 735/041.2, 735/041.4
• US Class Current: 1/1
• CPC Class Codes: B81B 3/0018 Structures acting upon the moving or flexible element for transforming energy into mechanical movement or vice versa, i.e. actuators, sensors, generators
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

An integrated microelectromechanical structure is provided with a driving mass, anchored to a substrate via elastic anchorage elements and designed to be actuated in a plane with a driving movement; and a first sensing mass and a second sensing mass, suspended within, and coupled to, the driving mass via respective elastic supporting elements so as to be fixed with respect thereto in said driving movement and to perform a respective detection movement in response to an angular velocity. In particular, the first and the second sensing masses are connected together via elastic coupling elements, configured to couple their modes of vibration.

Claims

1. A microelectromechanical structure, comprising:

a substrate;

a driving assembly having a first set of driving electrodes and a second set of driving electrodes;

elastic anchorage elements anchoring portions of the driving assembly to the substrate;

first and second elastic supporting elements;

a first sensing mass and a second sensing mass positioned between the first and second set of driving electrodes, the first sensing mass coupled to the driving assembly via the first elastic supporting element and the second sensing mass coupled to the driving assembly via the second elastic supporting element, the first and second sensing masses being configured to be moved by the driving assembly and configured to move in response to rotation of the microelectromechanical structure;

a rigid connection bar positioned between the first sensing mass and the second sensing mass;

first and second elastic coupling elements coupled between the first and second sensing masses and the connection bar, respectively, the elastic coupling elements configured to couple movement of the first and second sensing masses together to move at substantially the same frequency; and

a third sensing mass and a fourth sensing mass positioned between the first and second set of driving electrodes, the first and second sensing masses being aligned along a first axis and the third and fourth sensing masses being aligned along a second axis that is angled with respect to the first axis by less than 90 degrees, the third and fourth sensing masses being movably coupled to the driving assembly without being moveably coupled to the connection bar.

2. The structure of claim 1 wherein the driving assembly is configured to drive with a rotary motion.

3. The structure of claim 1 wherein the driving assembly includes a single driving mass having a rectangular opening along a reference axis, the first and second sensing masses being positioned within the rectangular opening.

4. The structure of claim 3 wherein the driving mass includes four additional openings that are arranged at angles from the reference axis where the angles are less than 90 degrees.

5. The structure of claim 4 wherein two of the four openings are separated from the other two openings by the rectangular opening.

6. The structure of claim 4 wherein the four additional openings are non-rectangular.

7. The structure of claim 1 wherein the connection bar has a first side and a second side that are each longer than a third side and a fourth side, the first elastic coupling element being coupled to the first side of the connection bar and the second elastic coupling element being coupled to the second side of the connection bar.

8. The structure of claim 7 wherein the connection bar is coupled to a driving mass with a third elastic coupling element.

9. The structure of claim 8 wherein the connection bar is coupled to the driving mass with a fourth elastic coupling element, the third elastic coupling element being coupled to the first side of the connection bar and the fourth elastic coupling element being coupled to the second side of the connection bar.

10. A gyroscope, comprising:

a substrate having a first reference axis and a second reference axis that is perpendicular to the first reference axis;

a driving assembly coupled to the substrate and having a first set of driving electrodes and a second set of driving electrodes;

a plurality of moveable masses coupled to the driving assembly and positioned between the first and second set of driving electrodes, a first pair of the plurality of moveable masses, each having a center of mass along a third axis that is between the first reference axis and second reference axis, a second pair of the plurality of moveable masses, each having a center of mass along the first reference axis, the first pair of movable masses being configured to detect rotation about the first reference axis and the second reference axis; and

a coupling element coupled between the second pair of the plurality of moveable masses to couple movement of the second pair of movable masses together without coupling the movement of the first pair of movable masses.

11. The gyroscope of claim 10 wherein the plurality of moveable masse includes a third pair of moveable masses, each having a center of mass along a fourth axis that is perpendicular to the third axis.

12. The gyroscope of claim 10 wherein the second pair of the plurality of moveable masses are configured to move together at substantially the same frequency.

13. A device, comprising:

a substrate;

a driving assembly having a plurality of driving electrodes;

a first moveable mass positioned between at least some of the plurality of driving electrodes, the first moveable mass being configured to be moved by the driving assembly and configured to move in response to an angular rotation of the device;

a second moveable mass positioned between at least some of the plurality of driving electrodes, the second moveable mass being configured to be moved by the driving assembly and configured to move in response to an angular rotation of the device; and

first and second elastic springs;

rigid coupling bar that is coupled between the first and second moveable masses, the coupling bar configured to cause the first and second moveable masses to be moved by the driving assembly at substantially the same frequency, the first elastic spring coupled between the coupling bar and the first mass and the second elastic spring coupled between the coupling bar and the second mass; and

a pair of third movable masses aligned with each other and positioned along a first axis, the first and second movable masses being aligned with each other and positioned along a second axis that is angled with respect to the first axis, the pair of third movable masses being moveably coupled to the driving assembly without being moveably coupled to the coupling bar such that the pair of third movable masses are configured to move without constraint by the coupling bar.

14. The device of claim 13, further comprising a third elastic spring and a fourth elastic spring each coupled between the coupling bar and the driving assembly.

15. The device of claim 14 wherein the third and fourth elastic springs are folded springs.

16. The device of claim 13 wherein the driving assembly is configured to drive with a rotary motion.

17. The device of claim 13 wherein the driving assembly includes a single driving mass, the first and second sensing masses being positioned within the driving mass.

18. The device of claim 17 wherein the driving mass is round.

19. The device of claim 17 wherein the coupling bar is coupled to the driving mass with third and fourth elastic springs.

20. The device of claim 13 wherein each mass of the pair of third movable masses is physically separate from the other mass of the pair of third movable masses.

21. A device, comprising:

a substrate having a first reference axis and a second reference axis that is perpendicular to the first reference axis;

a first pair of moveable masses located above the substrate, each having a center of mass along a third axis that is between the first reference axis and second reference axis;

a second pair of moveable masses located above the substrate, each having a center of mass along the first reference axis;

a driving assembly elastically coupled to the first and second pairs of moveable masses and configured to drive the first and second pairs of moveable masses; and

a coupling bar coupled between the second pair of moveable masses to couple movement of the second pair of movable masses together without coupling the first pair of movable masses to the coupling bar.

22. The device of claim 21 wherein the first pair of movable masses is configured to detect rotation about the first reference axis and the second reference axis.

23. The device of claim 21 wherein the second pair of movable masses is configured to detect rotation about a fourth axis that is perpendicular to the first and second reference axis.