Quadrature compensation for a rotation-rate sensor

• US 8,650,954 B2
• Filed: 11/23/2009
• Issued: 02/18/2014
• Est. Priority Date: 11/25/2008
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Hauer, Joerg, Gauger, Christoph
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US12/623,621
• Publication Number:
  US 20100132461A1
• Time in Patent Office: 1,548 Days
• Field of Search: 735/041.2, 735/041.4, 735/041.6
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames

Abstract

A rotation-rate sensor includes a substrate having a surface, a movable element situated above the surface, which is deflectable based on a Coriolis force along a first axis that runs perpendicular to the surface, a driving device which is prepared to activate the movable element along a second axis that runs parallel to the surface, a compensation device, in order to generate an electrostatic force along the first axis, including electrodes corresponding to one another, developed on the substrate and on the movable element; a relative degree of covering of the electrodes in the direction of the first axis being a function of the deflection of the movable element along the second axis; and the electrode developed on the movable element runs around an insulating region of the movable element.

Claims

1. A rotation-rate sensor comprising:

a substrate having a surface;

a movable element situated above the surface, that is deflectable, based on a Coriolis force, along a first axis running perpendicular to the surface, the movable element including at least one first electrode surrounding a recessed insulating region in the movable element;

a driving device for activating the movable element along a second axis that runs parallel to the surface;

a compensation device including a plurality of second electrodes and a current supply supplying a voltage to at least one of the second electrodes, wherein at least one of the second electrodes overlaps the at least one first electrode in a direction of the first axis by a degree that varies as a function of a deflection of the movable element along the second axis and the current supply applies a corrective voltage to the at least one second electrode to compensate for a deflection of the movable element along the first axis due to a change in position of the movable element along the second axis; and

first and second spring elements connecting respective first and second opposing edges of the movable element to at least one drive mass of the driving device, the first and second spring elements each including at least one flexure portion extending substantially parallel to the respective first or second opposing edge,

wherein the at least one first electrode of the movable element surrounds first and second pluralities of the recessed insulating regions, the first and second pluralities of recessed insulating regions each arranged in a linear grouping aligned with and proximate to a respective one of the first and second opposing edges.

2. The rotation-rate sensor according to claim 1, wherein compensation device includes at least one pair of second electrodes and the recessed insulating region in the movable element is aligned with the pair of second electrodes in the non-deflected state so the at least one first electrode covers a same area of each of the second electrodes in the pair.

3. The rotation-rate sensor according to claim 2, wherein the pair of second electrodes are situated on the substrate and are situated on different sides of a center line, which runs in a direction of a third axis that runs perpendicular to the second axis and parallel to the surface.

4. The rotation-rate sensor according to claim 3, wherein an insulating region of the movable element is situated symmetrically over the center line in a deflection-free position of the movable element in a direction of the second axis.

5. The rotation-rate sensor according to claim 3, further comprising at least one source supplying a first voltage between the electrode of the movable element and the first electrode and a second voltage between the electrode of the movable element and the second electrode that is different from the first voltage.

6. The rotation-rate sensor according to claim 5, wherein the first and second voltages differ in their signs, so that as a function of the sign of a deflection of the movable element along the second axis, an attractive or a repulsive force is exerted between the movable element and the substrate along the first axis.

7. The rotation-rate sensor according to claim 1, wherein a number of insulating regions in an edge region of the movable element have the electrode extending around them in such a way that fissures in an edge region of the movable element, that runs perpendicular to the first axis, are not created.

8. The rotation-rate sensor according to claim 7, wherein the edge region of the movable element forms four substantially straight outer edges.

9. The rotation-rate sensor according to claim 8, wherein a number of elastic elements are fastened to the outer edges of the movable element.