INTEGRATED MICROELECTROMECHANICAL GYROSCOPE WITH IMPROVED DRIVING STRUCTURE

• US 20110154898A1
• Filed: 12/22/2010
• Published: 06/30/2011
• Est. Priority Date: 12/24/2009
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Coronato, Luca, Cazzaniga, Gabriele
• Granted Patent: US 8,459,110 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

An integrated MEMS gyroscope, is provided with: at least a first driving mass driven with a first driving movement along a first axis upon biasing of an assembly of driving electrodes, the first driving movement generating at least one sensing movement, in the presence of rotations of the integrated MEMS gyroscope; and at least a second driving mass driven with a second driving movement along a second axis, transverse to the first axis, the second driving movement generating at least a respective sensing movement, in the presence of rotations of the integrated MEMS gyroscope. The integrated MEMS gyroscope is moreover provided with a first elastic coupling element, which elastically couples the first driving mass and the second driving mass in such a way as to couple the first driving movement to the second driving movement with a given ratio of movement.

Claims

1. An integrated MEMS gyroscope, comprising:

an assembly of driving electrodes;

a first driving mass, configured to be driven to have a first driving movement along a first axis in response to biasing of the assembly of driving electrodes, said first driving movement being configured to generate a first sensing movement, in response to rotations of said integrated MEMS gyroscope;

a second driving mass, configured to be driven to have a second driving movement along a second axis in response to the assembly of driving electrodes, said second axis being transverse to said first axis, said second driving movement being configured to generate a second sensing movement, in response to the rotations of said integrated MEMS gyroscope; and

a first elastic coupling element, configured to elastically couple said first driving mass and said second driving mass and to couple said first driving movement to said second driving movement with a ratio of movement.

2. The gyroscope according to claim 1, wherein said first driving movement is configured to generate, as a result of a Coriolis force, the first sensing movement that includes a first yaw sensing movement along said second axis, in response to the rotation of said integrated MEMS gyroscope about a third axis orthogonal to said first axis and said second axis at a yaw angular velocity, and a roll sensing movement along said third axis, in response to the rotation of said integrated MEMS gyroscope about said second axis at a roll angular velocity;

and wherein said second driving movement is configured to generate, as a result of a Coriolis force, the second sensing movement that includes a second yaw sensing movement along said first axis in response to the rotation of said integrated MEMS gyroscope about said third axis at said yaw angular velocity, and a pitch sensing movement along said third axis, in response to the rotation of said integrated MEMS gyroscope about said first axis at a pitch angular velocity.

3. The gyroscope according to claim 1, wherein said first elastic coupling element is configured to draw said second driving mass along by said first driving mass in said second driving movement, according to said ratio of movement.

4. The gyroscope according to claim 1, wherein said first elastic coupling element has an axis of extension in a direction inclined by an inclination angle, of non-zero value, with respect to said first axis, and is configured to transmit a relative movement between said first driving mass and said second driving mass along said axis of extension.

5. The gyroscope according to claim 4, wherein said inclination angle is 45°

, and said ratio of movement is substantially a ratio of 1;

1 where a displacement of said first driving mass corresponds to a substantially equal displacement of said second driving mass.

6. The gyroscope according to claim 1, wherein said first elastic coupling element is folded.

7. The gyroscope according to claim 1, wherein said first elastic coupling element is configured to enable said first and second driving movements to be oscillatory movements, synchronous with one another.

8. The gyroscope according to claim 1, wherein said assembly of driving electrodes is connected only to said first driving mass and not to said second driving mass.

9. The gyroscope according to claim 1, further comprising:

first elastic anchorage elements coupled between said first driving mass and a substrate of said integrated MEMS gyroscope, the first elastic anchorage elements being configured to constrain said first driving mass to perform said first driving movement along said first axis; and

second elastic anchorage elements coupled between said second driving mass and said substrate, the second elastic anchorage elements being configured to constrain said second driving mass to perform said second driving movement along said second axis.

10. The gyroscope according to claim 9, further comprising:

third elastic anchorage elements;

a third driving mass configured to be driven to have a third driving movement along said first axis in response to said assembly of driving electrodes, the third driving mass being anchored to said substrate by said third elastic anchorage elements;

fourth elastic anchorage elements;

a fourth driving mass configured to be driven to have a fourth driving movement along said second axis, the fourth driving mass being anchored to said substrate by said fourth elastic anchorage elements; and

second elastic coupling elements configured, together with said first elastic coupling element, to elastically couple said first, second, third, and fourth driving masses so that said first and third driving movements are synchronous and in phase opposition with respect to one another, and said second and fourth driving movements are synchronous and in phase opposition with respect to one another.

11. The gyroscope according to claim 10, wherein said second and fourth elastic anchorage elements are configured to enable said second driving mass and fourth driving mass, respectively, to perform the second sensing movement and a fourth sensing movement, respectively, in response to one and the same rotation of said integrated MEMS gyroscope at one and the same angular velocity;

12. The gyroscope according to claim 11, further comprising a sensing coupling structure configured to couple said second driving mass and said fourth driving mass elastically to one another, wherein said second and fourth sensing movement of the second and fourth driving mass are in phase opposition with respect to one another and are configured to inhibit in-phase movements of said second driving mass and fourth driving mass.

13. The gyroscope according to claim 12, wherein said sensing coupling structure comprises:

a rigid element configured to connect said second driving mass and fourth driving mass to one another, having a point of constraint in a position intermediate between them; and

a third elastic coupling element configured to connect respective ends of said rigid element to said second driving mass and fourth driving mass;

said point of constraint being substantially immobile in regard to translation.

14. The gyroscope according to claim 10, wherein said second elastic anchorage element and said fourth elastic anchorage element are configured to enable said second driving mass and said fourth driving mass, respectively, to perform a first pitch sensing movement and a second pitch sensing movement along said third axis in response to the rotation of said integrated MEMS gyroscope about said first axis at a pitch angular velocity, and a first yaw sensing movement and a second yaw sensing movement along said first axis in response to the rotation of said integrated MEMS gyroscope about said third axis at a yaw angular velocity.

15. The gyroscope according to claim 14, further comprising a first sensing mass coupled to said first driving mass via elastic decoupling elements, and to said second driving mass via said first elastic coupling element;

wherein said elastic decoupling elements are rigid in regard to said first driving movement and are configured to decouple said second sensing movements of said second driving mass and fourth driving mass from said first driving movement.

16. The gyroscope according to claim 1, further comprising:

first elastic supporting elements;

second elastic supporting elements;

a first sensing mass elastically coupled to the first driving mass with the first elastic supporting elements, the first sensing mass being fixed with respect to the first driving mass in the first driving movement, the first sensing mass having a first degree of freedom of movement in order to execute the first sensing movement; and

a second sensing mass elastically coupled to said second driving mass with the second elastic supporting elements, the second sensing mass being fixed with respect to the second driving mass in the second driving movement, the second sensing mass having a second degree of freedom of movement in order to execute the second sensing movement.

17. An electronic device, comprising:

an integrated MEMS gyroscope including;

an assembly of driving electrodes;

a first driving mass, configured to move in a first driving direction along a first axis in response to biasing of the assembly of driving electrodes, said first driving mass being configured to generate a first sensing movement, in response to rotations of said integrated MEMS gyroscope;

a second driving mass, configured to move in a second driving direction along a second axis in response to the assembly of driving electrodes, said second axis being transverse to said first axis, said second driving mass being configured to generate a second sensing movement, in response to the rotations of said integrated MEMS gyroscope; and

a first elastic coupling element, configured to elastically couple said first driving mass and said second driving mass in order to enable the first driving mass to move in the first driving direction and to enable the second driving mass to move in the second driving direction in a ratio of movement; and

a driving stage coupled to said integrated MEMS gyroscope and configured to supply electrical biasing signals to said assembly of driving electrodes to drive said first driving mass and said second driving mass.

18. The device according to claim 17 wherein said driving stage includes a single feedback control loop configured to control the driving of said first driving mass and of said second driving mass.

19. The device according to claim 18 wherein the first and second driving masses move in response to a single driving motion.

20. The device according to claim 17 wherein the first sensing movement is transverse to the first driving direction and the second sensing movement is transverse to the second driving direction.

21. The device according to claim 17 wherein the first sensing mass includes a first yaw sensing mass and a roll sensing mass and the second sensing mass includes a second yaw sensing mass and a pitch sensing mass.

22. A MEMS gyroscope, comprising:

a driving electrode;

a first driving mass, configured to move in a first driving direction along a first axis in response to the driving electrode;

a second driving mass, configured to move in a second driving direction along a second axis, the second axis being transverse to the first axis; and

a first elastic coupling element coupled between the first driving mass and the second driving mass, the first elastic coupling element being configured to move the second driving mass in the second driving direction in response to the driving electrode moving the first driving mass in the first driving direction.

23. The gyroscope of claim 22 wherein the first driving mass includes a first yaw sensing mass and a first roll sensing mass and the second driving mass includes a second yaw sensing mass and a first pitch sensing mass.

24. The gyroscope of claim 23 wherein the first yaw sensing mass is configured to generate a first sensing movement in response to rotations of the gyroscope, the first roll sensing mass is configured to generate a second sensing movement in response to the rotations of the gyroscope, the second yaw sensing mass is configured to generate a third sensing movement in response to rotations of the gyroscope, and the first pitch sensing mass is configured to generate a fourth sensing movement in response to the rotations of the gyroscope.

25. A method, comprising:

forming a MEMS gyroscope, the forming including;

forming a first driving mass having a first yaw sensing mass and a first roll sensing mass, the first driving mass configured to move in a first driving direction along a first axis;

forming a second driving mass having a second yaw sensing mass and a first pitch sensing mass, the second driving mass configured to move in a second driving direction along a second axis transverse to the first axis; and

forming an elastic coupling element between the first and second driving masses, the elastic coupling element configured to move the second driving mass in the second driving direction in response to a first driving movement of the first driving mass in the first driving direction.

26. The method of claim 25, further comprising forming a driving electrode electrically coupled to the first driving mass and configured to move the first driving mass in the first driving direction.

27. The method of claim 26 wherein the first driving movement is configured to generate a first sensing movement of the first yaw sensing mass in response to rotations of the MEMS gyroscope, a second sensing movement of the first roll sensing mass in response to the rotations of the MEMS gyroscope, a third sensing movement of the second yaw sensing mass in response to the rotations of the MEMS gyroscope, and a fourth sensing movement of the first pitch sensing mass in response to rotations of the MEMS gyroscope.