GYROSCOPE STRUCTURE AND GYROSCOPE

• US 20150211854A1
• Filed: 01/28/2015
• Published: 07/30/2015
• Est. Priority Date: 01/28/2014
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: RUOHIO, Jaakko, BLOMQVIST, Anssi
• Granted Patent: US 9,551,577 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B81B 2201/0242 Gyroscopes
• CPC Class Codes: B81B 2207/012 the micromechanical device and the control or processing electronics being separate parts in the same package
• CPC Class Codes: B81B 3/0043 Increasing angular deflection
• CPC Class Codes: G01C 19/5712 the devices involving a micromechanical structure
• CPC Class Codes: G01C 19/574 the devices having two sensing masses in anti-phase motion

Abstract

A gyroscope structure with a specific arrangement of drive and sense structures and coupling spring structures, which allows orthogonally directed motions of larger scale drive and sense structures in a very limited surface area.

Claims

1. A microelectromechanical gyroscope structure, comprising:

a first pair of drive structures comprising a first drive structure and a second drive structure, wherein said first drive structure is coupled to a first seismic mass and the second drive structure is coupled to a second seismic mass;

a second pair of drive structures comprising a third drive structure and a fourth drive structure, wherein the third drive structure is coupled to a third seismic mass and the fourth drive structure is coupled to a fourth seismic mass,

wherein each drive structure includes a transducer configured to induce primary oscillation of the corresponding seismic mass;

a first pair of sense structures comprising a first sense structure and a second sense structure;

a second pair of sense structures comprising a third sense structure and a fourth sense structure;

wherein the seismic masses of at least one pair of the first and second drive structures are coupled to oscillate in opposite phase and aligned to a common axis of primary oscillation, wherein an axis of primary oscillation of the first pair of drive structures and an axis of primary oscillation of the second pair of drive structures extend orthogonally along a plane of oscillation,

wherein each sense structure includes a sense device and a coupling spring structure, wherein the coupling spring structure connects the sense device to at least one seismic mass of the first pair of drive structures and to at least one seismic mass of the second pair of drive structures,

wherein the coupling structure is configured to relay to the sense device a component of the motion of each of the seismic masses in a direction perpendicular to their axis of primary oscillation, and to absorb a component of the motion of each of the seismic masses in a direction of their axis of primary oscillation, and

wherein the sense device is suspended to a static support and configured to oscillate in a direction diagonal to the axis of primary oscillation of the first pair of drive structures and diagonal to the axis of primary oscillation of the second pair of drive structures.

2. The microelectromechanical gyroscope structure of claim 1, wherein the first drive structure comprises a first vertical drive structure coupled to the first seismic mass and the second drive structure comprises a second vertical drive structure coupled to the second seismic mass,

wherein the third drive structure comprises a first horizontal drive structure coupled to the third seismic mass and the fourth drive structure comprises a second horizontal drive structure coupled to the fourth seismic mass,

wherein the first sense structure is coupled to the first seismic mass and the fourth seismic mass,

wherein the second sense structure is coupled to the second seismic mass and the third seismic mass,

wherein the third sense structure is coupled to the first seismic mass and the third seismic mass, and

wherein the fourth sense structure is coupled to the second seismic mass and the fourth seismic mass.

3. The microelectromechanical gyroscope structure of claim 1, wherein a direction diagonal to an axis of primary oscillation forms a 45°

(π

/4) angle with the axis of primary oscillation.

4. The microelectromechanical gyroscope structure of claim 1, wherein each of the drive structures includes a first spring structure that allows for the coupled seismic mass two degrees of freedom.

5. The microelectromechanical gyroscope structure of claim 4, wherein

the first spring structure includes a primary element for the first degree of freedom and a secondary element for the second degree of freedom,

the primary element includes an anchor element and a suspension spring that extends between one seismic mass of the seismic masses and the anchor element,

the suspension spring is elastic in the direction of the direction of the primary oscillation of the one seismic mass,

the secondary element couples the one seismic mass and the primary element and is elastic in a direction of the secondary oscillation of the one seismic mass, and wherein the direction of the secondary oscillation of the one seismic mass is orthogonal to the direction of the primary oscillation of the one seismic mass.

6. The microelectromechanical gyroscope structure of claim 1, further comprising a drive coupling spring configured to force the primary oscillation of opposite pairs of drive structures to anti-phase mode.

7. The microelectromechanical gyroscope structure of claim 6, wherein

the drive coupling spring comprises four diagonal beams, with one end of each of the diagonal beams being anchored to an anchor point between one of the first and second seismic masses and one of the third and fourth seismic masses,

wherein the diagonal beams extend from their respective anchor points toward a center point within the gyroscope structure, and

wherein another end of each of the diagonal beams is connected in a point of connection to two coupling means, one of which extends from the point of connection to the one of the first and second seismic masses, and another one of which extends from the point of connection to the one of the third and fourth seismic masses.

8. The microelectromechanical gyroscope structure of claim 1, wherein in each of the sense structures, the coupling spring structure includes a first sense beam and a second sense beam,

wherein the sense device includes a rotor that extends via an extension beam to a coupling point,

wherein the first sense beam extends between the coupling point and the at least one of the first and second seismic masses, and

wherein the second sense beam extends between the coupling point and the one of the third and fourth seismic masses.

9. The microelectromechanical gyroscope structure of claim 1, wherein

the sense device includes at least one flexible detection element, coupled to a coupling point, and configured to deflect according to motion of the coupling point, and

wherein one or more of the flexible detection elements includes a piezoelectric film deflecting along the deflection of the detection element.

10. A microelectromechanical gyroscope, comprising a microelectromechanical gyroscope structure according to claim 1.