Micromechanical sensor of angular velocity

• US 10,139,228 B2
• Filed: 02/05/2016
• Issued: 11/27/2018
• 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:
  US15/016,751
• Publication Number:
  US 20160231115A1
• Time in Patent Office: 1,026 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 an axis perpendicular to a plane. A coupling frame system couples the four open drive frames into a synchronized anti-phase driving motion. Phases of each of the four pairs of adjacent open drive frames are opposite, and amplitude of the linear primary motion of the four open drive frames are equal. Axes of linear driving motions of the open 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. Phases of each of the four pairs of adjacent detection masses are opposite. Axes of linear detection motion of each of the detection masses are aligned.

Claims

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

four open drive frames configured to be driven by exciting into an essentially linear driving motion;

four detection masses configured to double differentially detect angular velocity about an axis perpendicular to the plane of the micromechanical device;

a plurality of 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 the essentially linear driving motion of each open drive frame to the detection mass coupled to it, wherein the 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 driving motion; and

an inner coupling lever system for coupling the four detection masses into a synchronized anti-phase detection motion, wherein the detection motion of each of the four detection masses is essentially linear,

wherein mechanical coupling of the four open drive frames by a coupling frame system is configured to cause the four open drive frames to have mutually equal drive amplitudes and the four detection masses are configured to have mutually equal drive amplitudes.

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

3. The micromechanical device according to claim 1, wherein the four open drive frames are coupled to the coupling frame system for coupling said 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 collinear.

4. The micromechanical device according to claim 3, wherein

the four open drive frames are disposed in a fourfold symmetric configuration, wherein two adjacent detection masses in each four pairs of adjacent detection masses are configured to move in synchronized manner in phases opposite to one another, 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 four pairs of adjacent detection masses are configured to move in synchronized manner in opposite phase 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 in the plane of the micromechanical device and preventing in-phase and out-of-phase detection motion; and

wherein

a 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 synchronized anti-phase driving motion is relayed to a synchronized anti-phase primary motion of the four detection masses.

6. The micromechanical device according to claim 3, wherein the synchronized anti-phase driving motion is relayed from each one of the four open drive frames to the respective detection mass by a number of first springs placed symmetrically with respect to an axis aligned with the driving motion.

7. The micromechanical device according to claim 1, wherein the inner coupling lever system comprises:

two coupling levers, each coupling lever capable of rotating motion in the plane of the device;

two first bending springs, each coupling one of the two coupling levers to at least one suspension structure; and

a central spring for mutually coupling the two coupling levers with each other.

8. The micromechanical device according to claim 7, wherein each one of the two coupling levers comprises a first beam and a second beam, 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 to the central spring mutually coupling the two coupling levers,

wherein each end of the second beam is coupled to a respective detection mass with at least one first spring,

wherein the second beam is coupled via one of the first bending springs to a suspension point 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, and

wherein the first bending springs and the central spring are aligned with a symmetry line common to both two coupling levers when the device in rest and in driving motion.

9. The micromechanical device according to claim 1, wherein each detection mass is disposed in an enclosure within the respective open drive frame, the first springs having a higher spring constant in the direction of the driving motion, and a lower spring constant in the direction of the detection motion.

10. A micromechanical device for detecting angular velocity, comprising:

four open drive frames configured to be driven by exciting into an essentially linear driving motion;

four detection masses configured to double differentially detect angular velocity about an axis perpendicular to the plane of the micromechanical device;

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 the essentially linear driving motion of each open drive frame to the detection mass coupled to it; and

an inner coupling lever system for coupling the four detection masses into a synchronized anti-phase detection motion, wherein the detection motion of each of the four detection masses is essentially linear,

wherein the inner coupling lever system comprises;

two coupling levers, each coupling lever capable of rotating motion in the plane of the device;

two first bending springs, each coupling one of the two coupling levers to at least one suspension structure; and

a central spring for mutually coupling the two coupling levers with each other,

wherein each one of the two coupling levers comprises a first beam and a second beam,

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 to the central spring mutually coupling the two coupling levers,

wherein each end of the second beam is coupled to a respective detection mass with at least one first spring,

wherein the second beam is coupled via one of the first bending springs to a suspension point 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,

wherein the first bending springs and the central spring are aligned with a symmetry line common to both two coupling levers when the device in rest and in driving motion, and

wherein each end of the second beam of each of the two coupling levers is further coupled to at least one detection spring patterned in an enclosure within the respective detection mass, and the other end of the at least one detection spring is coupled to a suspension structure.

11. A micromechanical device for detecting angular velocity, comprising:

four open drive frames configured to be driven by exciting into an essentially linear driving motion;

four detection masses configured to double differentially detect angular velocity about an axis perpendicular to the plane of the micromechanical device;

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 the essentially linear driving motion of each open drive frame to the detection mass coupled to it; and

an inner coupling lever system for coupling the four detection masses into a synchronized anti-phase detection motion, wherein the detection motion of each of the four detection masses is essentially linear,

wherein the four open drive frames are coupled to a coupling frame system for coupling said 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 collinear, and

wherein the coupling frame system comprises

two long levers placed on first opposite sides of the micromechanical device, each long lever coupled with two different 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, when the driving masses are in driving motion,

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

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

providing a micromechanical device including four open drive frames and four detection masses for detecting angular velocity about an axis perpendicular to the plane of the micromechanical device;

driving the four open drive frames by exciting into an essentially linear driving motion;

relaying the essentially linear driving motion from each one of the four open drive frames to the respective detection mass by a plurality of first springs, wherein the 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 driving motion;

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

double differentially detecting said angular velocity about said axis with said four detection masses, wherein the detection motion of each of the four detection masses is essentially linear,

wherein mechanical coupling of the four open drive frames by a coupling frame system is configured to cause the four open drive frames to have mutually equal drive amplitudes and the four detection masses are configured to have mutually equal drive amplitudes.

13. The method according to claim 12, wherein axes of essentially linear detection motion of said four detection masses are collinear.

14. The method according to claim 12, further comprising coupling the four open drive frames into a synchronized anti-phase driving motion with the coupling frame system, wherein axes of essentially linear driving motion of said open drive frames are collinear.

15. The method according to claim 14, further comprising

exciting the four open drive frames to the synchronized anti-phase driving motion in a fourfold symmetric configuration, wherein each four pairs of two adjacent open drive frames move in synchronized manner in opposite phase to one another;

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 synchronized anti-phase detection motion of the four detection masses in a fourfold symmetric configuration, wherein each four pairs of two adjacent detection masses move in synchronized manner in opposite phase to one another; 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 in 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.

16. The method according to claim 14, 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.

17. The method according to claim 14, wherein the method comprises relaying the synchronized anti-phase driving motion from each one of the four open drive frames to the respective detection mass by a number of first springs arranged symmetrically with respect to an axis aligned with the driving motion.

18. The method according to claim 12, wherein the exciting of the four open drive frames causes the open drive frames to move in a synchronized anti-phase driving motion with mutually equal drive amplitudes and the four detection masses to move in a synchronized anti-phase primary motion with mutually equal drive amplitudes.