Sensor for detecting acceleration

• US 8,549,921 B2
• Filed: 10/12/2007
• Issued: 10/08/2013
• Est. Priority Date: 10/12/2006
• Status: Active Grant

• Current Assignee: Maxim Integrated GmbH (Analog Devices, Inc.), Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Maxim Integrated GmbH (Analog Devices, Inc.), Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Schwarzelbach, Oliver, Weiss, Manfred, Kempe, Volker
• Primary Examiner(s): Macchiarolo, Peter J
• Assistant Examiner(s): Shah, Samir M
• Application Number:
  US12/445,398
• Publication Number:
  US 20100139401A1
• Time in Patent Office: 2,188 Days
• Field of Search: 735/140.1, 735/143.2, 734/88, 735/143.8
• US Class Current: 73/514.32
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/18 in two or more dimensions
• CPC Class Codes: G01P 2015/0831 the mass being of the paddle type having the pivot axis between the longitudinal ends of the mass, e.g. see-saw configuration

Abstract

Exemplary embodiments relate to a sensor for detecting an acceleration acting on the sensor, having: a substrate, a mass unit, which acts as an inert mass in the event of the presence of an acceleration, a fixing structure, wherein the mass unit is articulated on the substrate in such a way that at least one pivot axis is defined, about which the mass unit can perform a rotation relative to the substrate as a result of an acceleration acting on the sensor, and the mass unit has an interial center of gravity, which is at a distance from the respective pivot axis, and at least one detection unit, with which a change in position between the mass unit and the substrate may be detected. The detection unit is arranged with respect to the mass unit in such a way that a deformation of the mass unit cannot be transferred to the detection unit.

Claims

1. A sensor for detecting an acceleration acting on the sensor, comprising:

a substrate;

a mass unit acting as an inertial mass in the presence of the acceleration;

a support structure, jointly coupling the mass unit to the substrate, wherein the mass unit is jointly connected to the substrate such that at least one pivot axis is defined around which the mass unit can perform a rotation relative to the substrate due to the acceleration acting on the sensor, and the mass unit comprises a centre of gravity offset from the at least one pivot axis; and

at least one detection unit, with which a change in position between the mass unit and the substrate is detectable, and the at least one detection unit is a capacitor,

wherein the at least one detection unit is positioned, with respect to the mass unit, such that a deformation of the mass unit is not transferable to the detection unit; and

wherein the support structure is positioned on the substrate such that an intersection of two mutually orthogonal pivot axes defines an anchor point around which the mass unit is rotatable according to two degrees of freedom.

2. The sensor according to claim 1, wherein the mass unit comprises a disc-like element.

3. The sensor according to claim 1, wherein the mass unit is axis-asymmetrically formed with respect to each pivot axis.

4. The sensor according to claim 1, wherein the mass unit comprises a bearing area that is axis-symmetrically formed with respect to the at least one pivot axis, on which the support structure and at least one detection unit are disposed.

5. The sensor according to claim 4, wherein the bearing area and the mass unit are connected to each other by a rigid rod shaped or bar shaped element.

6. The sensor according to claim 5, wherein the longitudinal axis of the rigid rod shaped or bar shaped element coincides with the at least one pivot axis.

7. The sensor according to claim 4, wherein the mass unit comprises a cavity in which the bearing area is disposed.

8. The sensor according to claim 7, wherein the at least one detection unit is located on the mass unit centrally on the edge surrounding the cavity.

9. The sensor according to claim 8, wherein the at least one detection unit serves for detecting changes in position in a plane of the mass unit.

10. The sensor according to claim 4, wherein the at least one detection unit disposed in the bearing area serves for detecting changes in position orthogonal to a plane of the mass unit.

11. The sensor according to claim 4, wherein two detection units for detecting a change in position in one direction are provided on the bearing area.

12. The sensor according to claim 1, wherein the sensor comprises at least one detection unit with which a change in position between the mass unit and the substrate caused by the acceleration acting on the sensor acting in a first direction is detectable, and at least one further detection unit with which a change in position between the mass unit and the substrate caused by an acceleration of the sensor acting along a second direction is detectable.

13. The sensor according to claim 1, wherein the support structure comprises a spring assembly that is displaceable along the direction of acceleration to be detected and is substantially bend resistant otherwise.

14. The sensor according to claim 1, wherein the capacitor is a differential capacitor formed from electrode combs.

15. The sensor according to claim 1, wherein it is formed from a wafer comprising a micromechanical device.

16. The sensor according to claim 15, wherein the wafer comprises a silicon wafer.

17. The sensor according to claim 1, wherein the mass unit comprises a bearing area on which the support structure and at least one detection unit are disposed;

the bearing area and the mass unit are connected to each other by a rigid element; and

the sensor comprises at least one detection unit with which a change in position between the mass unit and the substrate caused by the acceleration acting on the sensor acting in a first direction is detectable, and at least one further detection unit with which a change in position between the mass unit and the substrate caused by an acceleration of the sensor acting along a second direction is detectable.

18. A sensor for detecting an acceleration acting on the sensor, comprising:

a substrate;

a mass unit acting as an inertial mass in the presence of the acceleration;

a support structure, jointly coupling the mass unit to the substrate, wherein the mass unit is jointly connected to the substrate such that at least one pivot axis is defined around which the mass unit can perform a rotation relative to the substrate due to the acceleration acting on the sensor, and the mass unit comprises a centre of gravity offset from the at least one pivot axis; and

at least one detection unit, with which a change in position between the mass unit and the substrate is detectable, the at least one detection unit is a differential capacitor formed from electrode combs,

wherein the at least one detection unit is positioned, with respect to the mass unit, such that a deformation of the mass unit is not transferable to the detection unit; and

wherein the support structure is positioned on the substrate such that an intersection of two mutually orthogonal pivot axes defines an anchor point around which the mass unit is rotatable according to two degrees of freedom.