Triaxial acceleration sensor

• US 8,272,268 B2
• Filed: 08/19/2009
• Issued: 09/25/2012
• Est. Priority Date: 08/19/2008
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Classen, Johannes, Kaelberer, Arnd, Tebje, Lars
• Primary Examiner(s): Kwok, Helen C.
• Application Number:
  US12/543,649
• Publication Number:
  US 20100043549A1
• Time in Patent Office: 1,133 Days
• Field of Search: 735/143.2, 735/142.9, 735/143.6, 735/143.8, 735/10, 735/11
• US Class Current: 73/514.32
• 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

An acceleration sensor includes a substrate, a rocker mass, a z spring connected to the rocker mass, which allows the rocker mass to rotate about an axis, and at least one additional spring system connected to the substrate and the rocker mass. The additional spring system allows the rocker mass to deflect in an x or y direction oriented parallel or perpendicular to the axis. The z spring or the additional spring system allows the rocker mass to deflect in a y or x direction oriented parallel or perpendicular to the axis.

Claims

1. An acceleration sensor, comprising:

a substrate;

a rocker mass;

at least two z springs connected to the rocker mass and arranged to allow the rocker mass to rotate about an axis; and

at least one additional spring system connected to the substrate and the rocker mass;

wherein the additional spring system is configured to allow the rocker mass to deflect in at least one of (a) an x and (b) a y direction oriented one of (a) parallel and (b) perpendicular to the axis, at least one of (a) the at least two z springs and (b) the additional spring system configured to allow the rocker mass to deflect in at least one of (a) a y and (b) an x direction oriented one of (a) parallel and (b) perpendicular to the axis,

wherein the rocker mass is connected to a frame having an internal surface that is subdivided into two sections of different sizes by the at least two springs.

2. The acceleration sensor according to claim 1, wherein further comprising grid electrodes arranged opposite to substrate electrodes fixedly connected to the substrate, the grid electrodes and the substrate electrodes configured to allow a detection of a deflection of the rocker mass in at least one of (a) the x and (b) the y direction.

3. The acceleration sensor according to claim 1, further comprising at least one z electrode fixedly connected to the substrate arranged opposite to the rocker mass, the z electrode configured to allow a detection of a rotation of the rocker mass.

4. The acceleration sensor according to claim 3, wherein at least two z electrodes are provided, the z electrodes configured to allow a differential analysis of a rotation of the rocker mass.

5. The acceleration sensor according to claim 1, wherein the z spring is arranged as a torsion spring.

6. The acceleration sensor according to claim 1, wherein the additional spring system includes bending springs expansible in at least one of (a) the x and (b) the y direction.

7. The acceleration sensor according to claim 1, wherein the rocker mass is connected to an internal frame via the z spring, the internal frame connected to an external frame via two y springs, arranged on opposite sides of the internal frame and expansible in the y direction, the external frame connected to the substrate via two x springs, arranged on opposite sides of the external frame and expansible in the x direction, the rocker mass having y grid electrodes opposite to y substrate electrodes, fixedly connected to the substrate, the y grid electrodes and the y substrate electrodes configured to allow a detection of a deflection of the rocker mass in the y direction, the external frame having x grid electrodes opposite to x substrate electrodes, fixedly connected to the substrate, the x grid electrodes and the x substrate electrodes adapted to allow a detection of a deflection of the external frame in the x direction.

8. The acceleration sensor according to claim 1, wherein the rocker mass is connected to a frame via the z spring, the frame connected to the substrate via a plurality of x-y springs expansible in the x and y directions and situated on outer edges of the frame, the rocker mass having y grid electrodes, opposite to y substrate electrodes, fixedly connected to the substrate, the y grid electrodes and the y substrate electrodes configured to allow a detection of a deflection of the rocker mass in the y direction, the frame having x grid electrodes, opposite to x substrate electrodes fixedly connected to the substrate, the x grid electrodes and the x substrate electrodes configured to allow a detection of a deflection of the frame in the x direction.

9. The acceleration sensor according to claim 1, wherein the rocker mass is connected to a frame via the z spring, the z spring expansible in the y direction, the frame connected to the substrate via two x springs expansible in the x direction and situated on opposite sides of the frame, the rocker mass having y grid electrodes, opposite to y substrate electrodes fixedly connected to the substrate, the y grid electrodes and the y substrate electrodes configured to allow a detection of a deflection of the rocker mass in the y direction, the frame having x grid electrodes, opposite to x substrate electrodes fixedly connected to the substrate, the x grid electrodes and the x substrate electrodes configured to allow a detection of a deflection of the frame in the x direction.

10. The acceleration sensor according to claim 8, wherein the frame does not completely enclose the rocker mass.

11. The acceleration sensor according to claim 9, wherein the frame does not completely enclose the rocker mass.

12. The acceleration sensor according to claim 1, wherein the at least two springs are connected via a web and extend between two parallel bars of the frame.