QUADRATURE COMPENSATION

• US 20160153781A1
• Filed: 10/28/2014
• Published: 06/02/2016
• Est. Priority Date: 11/01/2013
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Blomqvist, Anssi, RYTK?NEN, Ville Pekka, PIIRAINEN, Tommi
• Granted Patent: US 9,897,447 B2
• Time in Patent Office: Days
• CPC Class Codes: G01C 19/56 Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: G01C 19/5726 Signal processing

Abstract

A microelectromechanical sensor device that comprises a seismic mass, and a spring structure that defines for the seismic mass a drive direction, and a sense direction that is perpendicular to the drive direction. A capacitive transducer structure includes a stator to be anchored to a static support structure, and a rotor mechanically connected to the seismic mass. The capacitive transducer structure is arranged into a slanted orientation where a non-zero angle is formed between the drive direction and a tangent of the stator surface. The slated capacitive transducer structure creates an electrostatic force to decrease quadrature error of the linear oscillation.

Claims

1. A microelectromechanical sensor device, comprising:

a seismic mass;

a spring structure for suspending the seismic mass into a static support structure, wherein the spring structure defines for the seismic mass a drive direction, and a sense direction that is perpendicular to the drive direction;

excitation means for driving the seismic mass into linear oscillation, the linear oscillation having a direction which has a primary component in the drive direction and a secondary component by quadrature error in the sense direction;

a capacitive transducer structure that includes;

a stator to be anchored to a static support structure and including at least one stator surface,

a rotor mechanically connected to the seismic mass, the rotor including a rotor surface positioned opposite the stator surface;

an electrical energy source configured to create an electrostatic force between the stator surface and the rotor surface;

wherein

the capacitive transducer structure is configured into a slanted orientation where a non-zero angle is formed between the drive direction and a tangent of the stator surface, and the electrostatic force is directed to decrease the secondary component of the linear oscillation.

2. A microelectromechanical sensor device of claim 1, wherein the stator surface and the rotor surface of the capacitive transducer structure are planar, or curved.

3. A microelectromechanical sensor device of claim 1, wherein the stator surface and the rotor surface of the capacitive transducer structure are initially aligned with each other.

4. A microelectromechanical sensor device of claim 1, wherein the capacitive transducer structure further comprises at least one rotor comb finger that includes an elongate rotor surface.

5. A microelectromechanical sensor device of claim 4, wherein the capacitive transducer structure further comprises a stator comb finger that includes an elongate stator surface, positioned such that the elongate stator surface extends opposite the elongate rotor surface.

6. A microelectromechanical sensor device of claim 4, wherein the capacitive transducer structure further comprises at least one pair of two rotor comb fingers, projecting to opposite directions from the seismic mass.

7. A microelectromechanical sensor device of claim 6, wherein the capacitive transducer structure is oriented such that the electrostatic force on one rotor comb finger of the pair of rotor comb fingers is opposite to the electrostatic force on the other rotor comb finger of the pair of rotor comb fingers.

8. A microelectromechanical sensor device of claim 7, further comprising one stator comb finger providing a stator surface for a rotor surface of one of the rotor comb fingers in one lateral position of the primary motion of the seismic mass, and another stator comb finger providing a stator surface for a rotor surface of the other one of the rotor comb fingers in the opposite lateral position of the primary motion of the seismic mass.

9. A microelectromechanical sensor device of claim 8, wherein the rotor surfaces of the pair of rotor comb fingers are in parallel.

10. A microelectromechanical sensor device of claim 8, wherein the stator surfaces of the stator comb fingers and the rotor surfaces of the rotor comb fingers are slanted by the non-zero angle in respect of the drive direction.

11. A microelectromechanical sensor device of claim 5, further comprising a first pair of stator and rotor comb fingers and a second pair of stator and rotor comb fingers, wherein the stator surface of the stator comb finger of the first pair of stator and rotor comb fingers and the rotor surface of the rotor comb finger of the first pair of stator and rotor comb fingers are slated by a positive non-zero angle in respect of the drive direction, and the stator surface of the stator comb finger of the second pair of stator and rotor comb fingers and the rotor surface of the rotor comb finger of the second pair of stator and rotor comb fingers are slanted by a negative non-zero angle in respect of the drive direction.

12. A microelectromechanical sensor device of claim 11, further comprising four pairs of stator and rotor comb fingers, the first pair of stator and rotor comb fingers and a second pair of stator and rotor comb fingers in one lateral position of the primary motion of the seismic mass, and similarly slanted third and fourth pair of stator and rotor comb fingers in the opposite lateral position of the primary motion of the seismic mass.

13. A microelectromechanical sensor device of claim 11, wherein the rotor comb finger of the first pair of stator and rotor comb fingers and the rotor comb finger of the second pair of stator and rotor comb fingers is formed of one tapered rotor comb finger element that includes a rotor surface slanted by the positive non-zero angle in respect of the drive direction, and a rotor surface slanted by the negative non-zero angle in respect of the drive direction.

14. A microelectromechanical sensor device of claim 5, wherein the stator and rotor comb fingers are configured in pairs into the slanted orientation such that:

in a stator comb finger of the stator and rotor comb finger pair, the stator surface that forms a side of the non-zero angle to the drive direction is planar and extends to the whole length of the stator comb finger;

in a rotor comb finger of the stator and rotor comb finger pair, the rotor surface is planar and is aligned parallel to the stator surface;

the opposite sides of the stator comb finger and rotor comb finger are aligned with the drive direction, forming a non-symmetric sawtooth-shaped compensation structure.

15. A microelectromechanical sensor device of claim 1, wherein the non-zero angle is in the range of 0.5-2°

.