MICROMECHANICAL SYSTEM

• US 20120031183A1
• Filed: 08/03/2011
• Published: 02/09/2012
• Est. Priority Date: 08/04/2010
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: NEUL, Reinhard, Meisel, Daniel Christoph
• Granted Patent: US 9,003,881 B2
• Time in Patent Office: Days
• US Class Current: 73/504.02
• CPC Class Codes: G01C 19/5755 the devices having a single sensing mass

Abstract

A yaw-rate sensor for determining a Coriolis force includes a semiconductor substrate, a mass body mounted so it is movable over the semiconductor substrate, a drive unit for setting the mass body into an oscillating movement, and a detection unit for determining a deflection of the mass body which is caused by the Coriolis force. The detection unit includes a piezoresistive element, whose electrical resistance is a function of the deformation of the piezoresistive element.

Claims

1. A yaw-rate sensor for determining a Coriolis force, comprising:

a semiconductor substrate;

a mass body mounted so it is movable over the semiconductor substrate;

a drive unit for setting the mass body into an oscillating movement; and

a detection unit for determining a deflection of the mass body caused by the Coriolis force, the detection unit including a piezoresistive element.

2. The yaw-rate sensor according to claim 1, wherein the mass body includes two mass elements, which are set into movements in opposite directions by the drive unit, and a piezoresistive element is situated between the mass elements and is operationally linked to the mass elements in such a way that deflections of the mass elements caused by the Coriolis force act in opposite directions on the piezoresistive element.

3. The yaw-rate sensor according to claim 1, wherein a piezoresistive element is operationally linked to the semiconductor substrate and a lever element, which is mounted in an anchor point so it is rotatable on a semiconductor substrate, is provided, and which is coupled to the mass body and the piezoresistive element so that a force or movement introduced by the mass body into the lever element is transmitted by the lever element using a conversion factor to the piezoresistive element.

4. The yaw-rate sensor according to claim 2, wherein a lever element is associated with each mass element, and the piezoresistive element is situated between the lever elements.

5. The yaw-rate sensor according to claim 4, wherein at least one lever element has an isolating element for electrical isolation, so that a part of the lever element and the piezoelectric element are electrically isolated from the semiconductor substrate.

6. The yaw-rate sensor according to claim 2, wherein a lever element is associated with each mass element, the lever elements are coupled to one another using a compensating spring, and the piezoresistive element is situated between one of the lever elements and a suspension point on the semiconductor substrate.

7. The yaw-rate sensor according to claim 6, wherein a second piezoresistive element, which is situated between a second lever element and a second suspension point, is provided and an electrical subtraction unit is provided, in order to compare signals provided by the piezoresistive elements.

8. The yaw-rate sensor according to claim 1, wherein the drive unit sets the mass body into movement electrostatically, magnetically, mechanically, optically, chemically, piezoelectrically, and/or thermally.

9. The yaw-rate sensor according to claim 1, wherein the drive unit and the detection unit are configured in such a way that a drive voltage of the drive unit is separated with respect to time and/or by differing frequency modulation from a measuring current of the detection unit.