Micromechanical rotation rate sensor with a coupling bar and suspension spring elements for quadrature suppression

• US 8,549,919 B2
• Filed: 08/18/2008
• Issued: 10/08/2013
• Est. Priority Date: 09/10/2007
• Status: Active Grant

• Current Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Original Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Inventors: Schmid, Bernhard, Gnthner, Stefan
• Primary Examiner(s): Williams, Hezron E
• Assistant Examiner(s): Shabman, Mark A
• Application Number:
  US12/677,240
• Publication Number:
  US 20100186507A1
• Time in Patent Office: 1,877 Days
• Field of Search: 735/041.4
• US Class Current: 73/504.14
• CPC Class Codes: G01C 19/574 the devices having two sensing masses in anti-phase motion

Abstract

A micromechanical rotation rate sensor including at least one substrate, wherein the base surface of the substrate is oriented parallel to the x-y plane of a Cartesian coordinate system, at least two seismic masses and in each case at least one suspension spring element for suspending the seismic mass from the substrate, wherein the at least two seismic masses are coupled to one another by at least one coupling bar, and at least one of the suspension spring elements includes at least two bar sections, which, in the undeflected state, are oriented essentially parallel to one another or are at an angle of less than 45° with respect to one another, and one or more connecting sections, which connect the bar sections to one another, wherein the bar sections can be displaced relative to one another in their longitudinal direction.

Claims

1. A micromechanical rotation rate sensor comprising:

at least one substrate, wherein a base surface of the substrate is oriented parallel to an x-y plane of a Cartesian coordinate system; and

at least two seismic masses and, in each case, at least one suspension spring element for suspending the seismic mass from the substrate;

at least one coupling bar for coupling the at least two seismic masses to one another;

wherein at least one of the suspension spring elements comprises at least two bar sections, which, in an undeflected state, are oriented substantially parallel to one another or are oriented at an angle of less than 45°

with respect to one another, and one or more connecting sections, which connect the bar sections to one another;

wherein the bar sections can be displaced relative to one another in their longitudinal direction,

wherein at least one of the suspension spring elements has a negative nonlinearity coefficient of a second order of spring stiffness.

2. The rotation rate sensor as claimed in claim 1, wherein the rotation rate sensor has one or more drive means for driving one or more seismic masses and at least one reading device, wherein the at least one drive means drives the at least two seismic masses in a y direction, and the rotation rate sensor is configured to sense rotation rates about an x axis and/or z axis.

3. The rotation rate sensor as claimed in claim 1, wherein the coupling bar is suspended from at least one spring element which is clamped on the substrate and forms therewith at least one anchoring point, wherein the spring element is embodied and clamped in or attached in such a way that the spring element prevents translatory deflections of the coupling bar.

4. The rotation rate sensor as claimed in claim 3, wherein the coupling bar is suspended substantially in a region of its center of gravity from the at least one spring element.

5. The rotation rate sensor as claimed in claim 4, wherein the at least one spring element from which the coupling bar is suspended is a torsion spring which permits rotational deflection of the coupling bar about a z axis and/or an x axis.

6. The rotation rate sensor as claimed in claim 4, wherein the center of gravity of the one or more coupling bars coincides substantially with a center of gravity of the rotation rate sensor.

7. The rotation rate sensor as claimed in claim 4, wherein the center of gravity of the one or more coupling bars coincides substantially with a center of gravity of the rotation rate sensor in an x-y plane.

8. The rotation rate sensor as claimed in claim 1, wherein the coupling bar is coupled at each of its ends to one or more seismic masses and/or one or more reading devices and/or one or more drive means, either directly or via at least one spring element.

9. The rotation rate sensor as claimed in claim 1, wherein the seismic masses are each embodied and arranged symmetrically with respect to an x-y plane and/or x-z plane and/or y-z plane with respect to a Cartesian coordinate system with the respective center point and/or center of gravity as a respective origin of the Cartesian coordinate system, and the seismic masses have a suspension means which is symmetrical with respect to said center of gravity.

10. The rotation rate sensor as claimed in claim 9, wherein the suspension means comprises four suspension spring elements.

11. The rotation rate sensor as claimed in claim 1, wherein at least one of the suspension spring elements has a substantially adjustable, linear, force deflection behavior in a direction of its bar sections.

12. The rotation rate sensor as claimed in claim 1, wherein at least one of the suspension spring elements has a coupling region and/or a coupling element which comprises an additional micromechanical spring element.

13. The rotation rate sensor as claimed in claim 12, wherein at least one of the suspension spring elements has fabrication parameters comprising at least spatial dimensions having values such that the spring has in the direction of its bar sections a substantially adjustable, linear, force deflection behavior, at least within a defined deflection interval.

14. The rotation rate sensor as claimed in claim 12, wherein material parameters of the bar sections and of the at least one connecting section and of the coupling regions and/or of the coupling elements, have values such that the spring has in the direction of its bar sections a substantially adjustable, linear, force deflection behavior, at least within a defined deflection interval.

15. The rotation rate sensor as claimed in claim 1, wherein at least one of the suspension spring elements is embodied in such a way that the bar sections and the connecting section or sections of the spring are embodied and arranged in a substantially u-shape, v-shape or s-shape in the undeflected state.

16. The rotation rate sensor as claimed in claim 1, wherein at least one of the suspension spring elements has a substantially adjustable, linear, force deflection behavior which is determined at least by an embodiment of the bar sections with defined lengths and widths and by an arrangement of the at least two bar sections at a defined distance from one another.

17. The rotation rate sensor as claimed in claim 1, wherein a crystal structure of a material of at least one of the suspension spring elements is oriented in such a way that a plane that is normal to a crystal lattice plane is oriented essentially 45°

with respect to a plane that is normal to the substrate from which the spring is fabricated.

18. The rotation rate sensor as claimed in claim 1, wherein at least one of the suspension spring elements is embodied in such a way that an absolute value of a second order nonlinearity coefficient (β

) of a spring stiffness with respect to a deflection that is substantially in a direction of the bar sections of the at least one suspension spring element is less than 2,000,000 (units of meters<sup>−

2</sup>).

19. The rotation rate sensor as claimed in claim 1, wherein at least one of the suspension spring elements is embodied in such a way that an absolute value of a second order nonlinearity coefficient (β

) of a spring stiffness with respect to a deflection that is substantially in a direction of the bar sections of the at least one suspension spring element is less than 300,000 (units of meters<sup>−

2</sup>).

20. The rotation rate sensor as claimed in claim 1, wherein at least one of the suspension spring elements has a force deflection behavior such that the suspension spring element compensates a nonlinear force deflection behavior of a seismic mass in a driving direction that is caused by an undesired force deflection behavior of one or more other suspension spring elements, and the seismic mass has a substantially linear force deflection behavior in the driving direction, and the at least one suspension spring element has a force deflection behavior that is set in a defined fashion.

21. The rotation speed sensor as claimed in claim 1,

wherein the rotation speed sensor is configured to sense a rotation rate about an x-axis,

wherein the seismic masses are driven in a y-direction,

wherein the seismic masses are suspended from suspension spring elements, at least one of which is of rigid design in an x-direction in each case,

wherein the coupling bar is suspended from the substrate by a torsion spring which permits torsion about the x-axis and is rigid in the x and z-directions, and said coupling bar is coupled at each of its two ends to the seismic masses by spring elements.

22. The rotation rate sensor as claimed in claim 1,

wherein the rotation speed sensor is configured to sense a rotation rate about an x-axis and a z-axis,

wherein the seismic masses are driven in a y-direction,

wherein the coupling bar is suspended from the substrate by a torsion spring which permits torsion about the x-axis and the z-axis and is rigid in an x-direction and z-direction.

23. The rotation rate sensor as claimed in claim 1, wherein the rotation rate sensor is embodied as a micro-electro-mechanical system (MEMS) or MEMS module which has mechanical and electronic means for connecting to and/or interacting with further MEMS modules and/or with at least one electronic signal processing circuit.

24. A method for manufacturing a rotation rate sensor comprising the step of forming micromechanical elements by a manufacturing process for manufacturing micromechanical systems from a substrate which is composed from crystalline silicon or a plurality of layers of semiconductor material and/or metal or metals, wherein the rotation rate sensor is embodied as claimed in claim 1.