Micromechanical sensor of angular velocity

• US 9,927,241 B2
• Filed: 02/05/2016
• Issued: 03/27/2018
• Est. Priority Date: 02/11/2015
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Piirainen, Tommi
• Primary Examiner(s): Chapman, Jr., John
• Application Number:
  US15/016,805
• Publication Number:
  US 20160231116A1
• Time in Patent Office: 781 Days
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames

Abstract

A micromechanical device includes four open drive frames and four detection masses for double differentially detecting angular velocity about a single axis aligned with the plane of the micromechanical device. A coupling frame system couples the four open drive frames into a synchronized anti-phase driving motion. In each four pairs of adjacent open drive frames, two adjacent open drive frames move in phases opposite to each other. Axes of linear driving motion of each of the drive frames are aligned. Anti-phase synchronized driving motion of the open drive frames is relayed through a spring arrangement to an anti-phase synchronized driving motion of the four detection masses. An inner coupling lever system couples the four detection masses into a synchronized anti-phase detection motion. In each four pairs of adjacent detection masses, phases of two adjacent detection masses are opposite. Axes of linear detection motion of the detection masses are aligned.

Claims

1. A micromechanical device for detecting angular velocity, said device comprising:

four open drive frames, each forming a semi-open enclosure;

four detection masses, each disposed within the semi-open enclosure formed by the respective open drive frame, the

four detection masses configured to double differentially detect angular velocity about a single rotation axis aligned with a plane of the device;

an inner coupling lever system for coupling the four detection masses into a synchronized anti-phase detection motion; and

first springs coupling each one of the four detection masses to a respective one of the four open drive frames, the first springs being configured to relay a linear driving motion of each open drive frame to a detection mass coupled to it and wherein, for each of the detection masses, a plurality of first springs coupling the detection mass to the respective open drive frame are disposed symmetrically with respect to an axis aligned with the linear driving motion.

2. The micromechanical device according to claim 1, wherein axes of essentially linear detection motion of said detection masses are collinear.

3. The micromechanical device according to claim 1, wherein the four open drive frames are coupled to a coupling frame system for coupling the four open drive frames into a synchronized anti-phase driving motion, and wherein axes of essentially linear driving motion of said open drive frames are aligned.

4. The micromechanical device according to claim 3, wherein

the four open drive frames are disposed in a fourfold symmetric configuration, and wherein, in each four pairs of adjacent open drive frames, the adjacent open drive frames are configured to move in a synchronized manner in phases opposite to each other, wherein

each of the four open drive frames is coupled with a spring to the coupling frame system, the coupling frame system allowing the synchronized anti-phase driving motion in the plane of the micromechanical device and preventing in-phase and out-of-phase driving motion;

wherein

the four detection masses are placed in a fourfold symmetric configuration, wherein two adjacent detection masses in each of the four pairs of adjacent detection masses are configured to move in a synchronized manner in phases opposite to one another;

wherein

each of the four detection masses is coupled with at least one spring to the inner coupling lever system, the inner coupling lever system allowing the synchronized anti-phase detection motion perpendicular to the plane of the device and preventing in-phase and out-of-phase detection motion; and

wherein

direction of said synchronized anti-phase driving motion is perpendicular to direction of said synchronized anti-phase detection motion.

5. The micromechanical device according to claim 3, wherein the coupling frame system comprises:

two long levers placed on first opposite sides of the micromechanical device, each long lever coupled with two second springs with different two adjacent open drive frames, wherein each open drive frame is coupled with exactly one long lever in a single point of coupling, wherein a point of coupling is placed on a symmetry axis of the respective open drive frame; and

four short levers arranged in pairs of two adjacent short levers, each pair of said short levers placed on second opposite sides of the micromechanical device, wherein levers in each pair of short levers are mutually coupled with a first spring arrangement comprising a loop and two oblique springs, the first spring arrangement allowing the two adjacent short levers to move in opposite phase and preventing the two adjacent short levers from moving in same phase,

wherein adjacent ends of said long levers and short levers are coupled with each other at or near said adjacent ends of the respective levers, and

wherein each of the two long levers is coupled by a third spring with a suspension structure, at half-way of the length of the long lever, wherein the long lever is configured to rotate in the level of the device about the point of coupling to the suspension structure.

6. The micromechanical device according to claim 3, wherein the synchronized anti-phase driving motion is relayed to a synchronized anti-phase primary motion of the four detection masses.

7. The micromechanical device according to claim 1, wherein

the four open drive frames are configured to have mutually equal drive amplitudes and the four detection masses are configured to have mutually equal drive amplitudes.

8. The micromechanical device according to claim 1, wherein the inner coupling lever system includes two first levers having a first common rotation axis, each of the two first levers being coupled with two torsion springs placed along the first common rotation axis on opposite sides of each of the two first levers and said two torsion springs coupling each of the two first levers to at least two suspension structures, wherein each of the two first levers is further coupled with different two detection masses, and the two first levers are arranged to couple the detection motion of the respective two detection masses to opposite phases.

9. The micromechanical device according to claim 8, wherein each one of the two first levers comprises a first beam and a second beam, and

wherein a first end of the first beam is attached to a first side of the second beam at half-way of the length of the second beam;

wherein a second end of the first beam is coupled with a first torsion spring to a first suspension structure common to both two first levers;

wherein each end of the second beam is coupled to a respective detection mass with at least one fourth spring; and

wherein the second beam is coupled with a second torsion spring to a second suspension structure at half-way of the length of the second beam, on the side of the second beam that is opposite to the side of attaching the first beam.

10. The micromechanical device according to claim 9, wherein each end of the second beam of each of the two first levers is coupled to at least one detection spring structure patterned in an enclosure within the respective detection mass, and wherein the other end of the at least one detection spring is coupled to a suspension structure.

11. The micromechanical device according to claim 8, wherein the inner coupling lever system further includes two second levers having a second common rotation axis perpendicular to the first common rotation axis, and the first common rotation axis and the second common rotation axis having a common crossing point in the plane of the micromechanical device, each of the two second levers being coupled with two torsion springs placed along the second common rotation axis on opposite sides of each of the two second levers and the two torsion springs coupling each of the two first levers to at least two suspension structures.

12. The micromechanical device according to claim 11, wherein the two first levers are coupled with the two second levers with four springs, one spring coupling each two adjacent first lever and second lever, first end of the springs being attached symmetrically to each respective first lever an equal distance away from the first common rotation axis and the second end of the springs being attached symmetrically to each respective second lever, an equal distance away from the second common rotation axis.

13. The micromechanical device according to claim 1, wherein the first springs have a higher spring constant in the direction of the driving motion, and a lower spring constant in the direction of the detection motion.

14. A method for operating a micromechanical device for detecting angular velocity, said method comprising:

providing a micromechanical device including four open drive frames, each forming a semi-open enclosure, and four detection masses, each disposed within the semi-open enclosure formed by the respective open drive frame, the four detection masses configured to double differentially detect angular velocity about a single rotation axis aligned with the plane of the micromechanical device;

coupling the four detection masses into a synchronized anti-phase detection motion with an inner coupling lever system; and

coupling each one of the four detection masses to a respective one of the four open drive frames with first springs, which are configured to relay a linear driving motion of each open drive frame to a detection mass coupled to it, and wherein for each of the detection masses, a plurality of first springs coupling the detection mass to the respective open drive frame are disposed symmetrically with respect to an axis aligned with the linear driving motion.

15. The method according to claim 14, wherein, in said synchronized anti-phase detection motion, axes of detection motion of each of said detection masses are collinear, and wherein in each four pairs of two adjacent detection masses the two adjacent detection masses move in phases opposite to each other.

16. The method according to claim 15, further comprising coupling the four open drive frames into a synchronized anti-phase driving motion with a coupling frame system,

wherein axes of driving motion of said open drive frames are aligned, and wherein in each four pairs of adjacent open drive frames the two adjacent open drive frames move in phases opposite to each other.

17. The method according to claim 16, further comprising:

exciting the four open drive frames to the anti-phase driving motion in a fourfold symmetric configuration;

coupling each of the four open drive frames with a spring to the coupling frame system, the coupling frame system allowing the synchronized anti-phase driving motion in the plane of the micromechanical device and preventing in-phase and out-of-phase driving motion;

causing the anti-phase driving motion of the four detection masses placed in a four-fold symmetric configuration; and

coupling each of the four detection masses with at least one spring to the inner coupling lever system, the inner coupling lever system allowing the synchronized anti-phase detection motion perpendicular to the plane of the micromechanical device and preventing in-phase and out-of-phase detection motion,

wherein the direction of said synchronized anti-phase driving motion is perpendicular to the direction of said synchronized anti-phase detection motion.

18. The method according to claim 16, wherein

the exciting of the four open drive frames causes the open drive frames to move in the anti-phase driving motion with mutually equal drive amplitudes and the four detection masses to move in anti-phase primary motion with mutually equal drive amplitudes.

19. The method according to claim 16, wherein the method comprises relaying the synchronized anti-phase driving motion to the four detection masses for causing a synchronized anti-phase primary motion of the four detection masses.