Mechanism for selective coupling in microelectromechanical systems inertial sensors
Couplers for selectively coupling in-plane and out-of-plane motion between moving masses are provided herein. In particular, aspects of the present application provide for a coupler configured to couple in-plane motion between moving masses while decoupling out-of-plane motion between the moving masses. The selective couplers as described herein may be used in a device, such as a microelectromechanical systems (MEMS) inertial sensor. In some embodiments, a MEMS inertial sensor comprises a first mass configured to move in-plane, a second mass configured to move in-plane and out-of-plane, and a coupler coupling the first and second masses and comprising two levers coupled to an anchor point by respective tethers and coupled to each other by a spring.
1. A microelectromechanical systems (MEMS) inertial gyroscope, comprising:
a sensing mass configured to be driven in-plane and to move out-of-plane in response to rotation of the MEMS inertial gyroscope;
a mechanical drive array configured to move in-plane to drive the sensing mass in-plane; and
a coupler coupling the mechanical drive array and the sensing mass and comprising two levers coupled to an anchor point by respective tethers and coupled to each other by a spring, wherein each of the respective tethers is compliant to in-plane and out-of-plane motion.
2. The MEMS inertial gyroscope of claim 1 , further comprising respective end connections connecting the two levers to the mechanical drive array and the sensing mass.
3. The MEMS inertial gyroscope of claim 1 , wherein the two levers comprise first and second levers, and a length of the second lever is at least twice a length of the first lever.
4. The MEMS inertial gyroscope of claim 3 , wherein the first lever is coupled to the mechanical drive array by an end connection.
5. The MEMS inertial gyroscope of claim 1 , wherein the two levers comprise first and second levers, the first lever is coupled to a first end of the spring and the second lever is coupled to a second end of the spring.
6. A microelectromechanical systems (MEMS) inertial sensor, comprising:
a substrate; and
first and second masses coupled to the substrate, and coupled together by a coupler and configured to move in-plane with each other;
wherein the coupler comprises two levers coupled to respective masses of the first and second masses, the two levers being tethered to an anchor by respective tethers and coupled to each other by a spring;
wherein each of the respective tethers is compliant to in-plane and out-of-plane motion; and
the first mass comprises a drive array configured to cause in-plane motion of the second mass and the MEMS inertial sensor is a gyroscope configured to detect rotation from out-of-plane motion of the second mass.
7. The MEMS inertial sensor of claim 6 , wherein the spring is a folded spring.
8. The MEMS inertial sensor of claim 6 , wherein the spring comprises first and second longer segments joined by a shorter segment.
9. The MEMS inertial sensor of claim 6 , wherein at least one of the tethers comprises a folded tether.
10. The MEMS inertial sensor of claim 6 , wherein the two levers are substantially in-line with each other.
11. The MEMS inertial sensor of claim 10 , wherein the spring is offset from the two levers.
12. The MEMS inertial sensor claim 6 , wherein the two levers are offset from each other and the spring comprises a straight spring.
13. A microelectromechanical systems (MEMS) device, comprising:
a substrate;
a first mass;
a second mass; and
a coupler coupling the first and second masses together and configured to transfer in-plane motion between the first and second masses and to decouple out-of-plane motion of the first and second masses, wherein the coupler comprises first and second levers coupled to an anchor point by respective tethers and coupled to each other by a spring, and
wherein at least one of the respective tethers is compliant to in-plane and out-of-plane motion, the first mass comprises a drive array configured to cause in-plane motion of the second mass, and the MEMS device is a gyroscope configured to detect in-plane rotation from out-of-plane motion of the second mass.
14. The MEMS device of claim 13 , wherein the coupler is configured to absorb the out-of-plane motion of the first and second masses.
15. The MEMS device of claim 13 , wherein the spring comprises a folded spring coupling the first and second levers.