MULTIPLE AXIS RATE SENSOR

• US 20140260610A1
• Filed: 03/15/2013
• Published: 09/18/2014
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Freescale Semiconductor, Inc. (NXP Semiconductors NV)
• Inventors: McNeil, Andrew C., Lin, Yizhen
• Granted Patent: US 9,506,756 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure

Abstract

A microelectromechanical systems (MEMS) device includes at least two rate sensors (20, 50) suspended above a substrate (30), and configured to oscillate parallel to a surface (40) of the substrate (30). Drive elements (156, 158) in communication with at least one of the rate sensors (20, 50) provide a drive signal (168) exhibiting a drive frequency. One or more coupling spring structures (80, 92, 104, 120) interconnect the rate sensors (20, 50). The coupling spring structures enable oscillation of the rate sensors (20, 50) in a drive direction dictated by the coupling spring structures. The drive direction for the rate sensors (20) is a rotational drive direction (43) associated with a first axis (28), and the drive direction for the rate sensors (50) is a translational drive direction (64) associated with a second axis (24, 26) that is perpendicular to the first axis (28).

Claims

1. A microelectromechanical systems (MEMS) device comprising:

a first rate sensor;

a second rate sensor, said first and second rate sensors being configured to oscillate parallel to a planar surface;

drive elements in communication with at least one of said first and second rate sensors for providing a drive signal exhibiting a drive frequency; and

a first coupling spring structure interconnecting said first and second rate sensors, said first coupling spring structure enabling oscillation of said first and second rate sensors at said drive frequency in a drive direction dictated by said coupling spring structure, wherein said drive direction for said first rate sensor is a first drive direction associated with a first axis and said drive direction for said second rate sensor is a second drive direction associated with a second axis, said second axis being perpendicular to said first axis.

2. A MEMS device as claimed in claim 1 wherein each of said first and second rate sensors comprises:

a drive frame having a central opening; and

a sense mass positioned in said central opening and flexibly coupled to said drive frame, wherein said first coupling spring structure is interconnected with said drive frame of said each of said first and second rate sensors.

3. A MEMS device as claimed in claim 1 wherein:

said first axis is perpendicular to said planar surface, said first drive direction is a rotational drive direction such that said first rate sensor is driven in said rotational drive direction about said first axis;

said second axis is parallel to said planar surface, said second drive direction is a translational drive direction such that said second rate sensor is driven in said translational drive direction parallel to said second axis; and

said first coupling spring structure interconnecting said first and second rate sensors is stiff in said translational drive direction and compliant relative to a third axis that is orthogonal to each of said first and second axes.

4. A MEMS device as claimed in claim 1 further comprising:

a third rate sensor disposed beside said second rate sensor; and

a second coupling spring structure interconnecting said second and third rate sensors, said second coupling spring structure enabling oscillation of said third rate sensor at said drive frequency in said drive direction dictated by said second coupling spring structure.

5. A MEMS device as claimed in claim 4 wherein said drive direction for said third rate sensor is said second drive direction, and said second coupling spring structure constrains said oscillation of said second and third rate sensors to anti-phase motion.

6. A MEMS device as claimed in claim 4 wherein said drive direction for said third rate sensor is said second drive direction, and said second coupling spring structure constrains oscillation of said second and third rate sensors to in-phase motion.

7. A MEMS device as claimed in claim 4 further comprising:

a fourth rate sensor disposed beside said third rate sensor; and

a third coupling spring structure interconnecting said third and fourth rate sensors, said third coupling spring structure enabling oscillation of said fourth rate sensor at said drive frequency in said drive direction dictated by said third coupling spring structure.

8. A MEMS device as claimed in claim 7 wherein said first, second, third, and fourth rate sensors are arranged in a row.

9. A MEMS device as claimed in claim 7 wherein:

said first, second, third, and fourth rate sensors are arranged around a central location of said planar surface; and

said MEMS device further comprises a fourth coupling spring structure interconnected between said first and fourth rate sensors.

10. A MEMS device as claimed in claim 1 wherein said first coupling spring structure comprises:

a first spring element coupled to said first rate sensor;

a second spring element coupled to said second rate sensor; and

a pivot lever having an anchor coupled to said planar surface, said pivot lever being configured to oscillate about a pivot axis centered at said anchor and perpendicular to said planar surface, said first spring element being coupled to said pivot lever, and said second spring element being coupled to said pivot lever.

11. A MEMS device as claimed in claim 10 wherein:

said first rate sensor exhibits a first midline oriented parallel to said planar surface, said first spring element being coupled with said first rate sensor at a location offset from said first midline; and

said second rate sensor exhibits a second midline oriented parallel to said planar surface and parallel to said first midline, said second spring element being coupled with said second rate sensor at a second location along said second midline.

12. A MEMS device as claimed in claim 11 wherein:

said first axis is perpendicular to said planar surface, said first drive direction is a rotational drive direction;

said second axis is parallel to said planar surface, said second drive direction is a translational drive direction; and

said first and second spring elements are stiff in said translational drive direction and compliant relative to a third axis that is orthogonal to each of said first and second axes.

13. A MEMS device as claimed in claim 1 further comprising:

a third rate sensor disposed beside said second rate sensor; and

a second coupling spring structure interconnecting said second and third rate sensors, said second coupling spring structure enabling oscillation of said third rate sensor at said drive frequency in said drive direction dictated by said second coupling spring structure, said second coupling spring structure including;

a first spring element coupled to said second rate sensor;

a second spring element coupled to said third rate sensor; and

a pivot lever having an anchor coupled to said planar surface, said pivot lever being configured to oscillate about a pivot axis centered at said anchor and perpendicular to said planar surface, said first spring element being coupled to said pivot lever, and said second spring element being coupled to said pivot lever.

14. A MEMS device as claimed in claim 13 wherein:

said second axis is parallel to said planar surface, said second drive direction is a translational drive direction;

said drive direction for said third rate sensor is said second drive direction;

said first and second spring elements are stiff in said translational drive direction and compliant relative to a third axis that is orthogonal to each of said first and second axes.

15. A MEMS device as claimed in claim 13 further comprising:

a fourth rate sensor disposed beside said third rate sensor such that said first, second, third, and fourth rate sensors are arranged in a row;

a third coupling spring structure interconnecting said third and fourth rate sensors, said third coupling spring structure enabling oscillation of said fourth rate sensor at said drive frequency in said drive direction dictated by said third coupling spring structure; and

said second coupling spring structure further includes a third spring element and a fourth spring element, said third spring element being coupled to each of said first rate sensor and said pivot lever, and said fourth spring element being coupled to each of said fourth rate sensor and said pivot lever.

16. A microelectromechanical systems (MEMS) device comprising:

a plurality of rate sensors configured to oscillate parallel to a planar surface;

drive elements in communication with at least one of said rate sensors for providing a drive signal exhibiting a drive frequency; and

coupling spring structures interconnecting said plurality of rate sensors, said coupling spring structures enabling oscillation of each of said plurality of rate sensors at said drive frequency in a drive direction dictated by said coupling spring structures, wherein;

said drive direction for a first subset of said rate sensors is a rotational drive direction associated with a first axis that is perpendicular to said planar surface, such that said first subset of said rate sensors is driven into rotational oscillation about said first axis; and

said drive direction for a second subset of said rate sensors is a translational drive direction associated with a second axis that is parallel to said planar surface, such that said second subset of said rate sensors is driven into translational oscillation parallel to said second axis.

17. A MEMS device as claimed in claim 16 wherein said plurality of rate sensors comprises:

a first rate sensor;

a second rate sensor interconnected with said first rate sensor via a first one of said coupling spring structures;

a third rate sensor interconnected with said second rate sensor via a second one of said coupling spring structures; and

a fourth rate sensor interconnected with said third rate sensor via a third one of said coupling spring structures, wherein said first and fourth rate sensors form said first subset of said rate sensors configured to undergo said rotational oscillation and said second and third rate sensors form said second subset of said rate sensors configured to undergo said translational oscillation.

18. A MEMS device as claimed in claim 17 wherein said second one of said coupling spring structures constrains said translational oscillation of said second and third rate sensors to anti-phase motion.

19. A microelectromechanical systems (MEMS) device comprising:

a first rate sensor;

a second rate sensor;

a third rate sensor;

a fourth rate sensor, said first, second, third, and fourth rate sensors being configured to oscillate parallel to a planar surface;

drive elements in communication with at least one of said first, second, third, and fourth rate sensors for providing a drive signal exhibiting a drive frequency; and

a plurality of coupling spring structures including a first coupling spring structure interconnecting said first and second rate sensors, a second coupling spring structure interconnecting said second and third rate sensors, a third coupling spring structure interconnecting said third and fourth rate sensors, and a fourth coupling spring structure interconnecting said first and fourth rate sensors, said plurality of coupling spring structures enabling oscillation of each of said plurality of rate sensors at said drive frequency in a drive direction dictated by said coupling spring structures, wherein said drive direction for said first and fourth rate sensors is a first drive direction associated with a first axis and said drive direction for said second and third rate sensors is a second drive direction associated with a second axis, said second axis being perpendicular to said first axis.

20. A MEMS device as claimed in claim 19 wherein:

said first coupling spring structure comprises a first spring element coupled to said first rate sensor, a second spring element coupled to said second rate sensor, and a first pivot lever having a first anchor coupled to said planar surface, said first pivot lever being configured to oscillate about a first pivot axis centered at said first anchor and perpendicular to said planar surface, each of said first and second spring elements being coupled to said first pivot lever; and

said third coupling spring structure comprises a third spring element coupled to said third rate sensor, a fourth spring element coupled to said fourth rate sensor, and a second pivot lever having a second anchor coupled to said planar surface, said second pivot lever being configured to oscillate about a second pivot axis centered at said second anchor and perpendicular to said planar surface, each of said third and fourth spring elements being coupled to said second pivot lever, and said second pivot lever being configured to oscillate in synchronism with said first pivot lever.