Micromechanical roatational rate sensor

• US 20040154398A1
• Filed: 04/02/2004
• Published: 08/12/2004
• Est. Priority Date: 01/30/2002
• Status: Abandoned Application

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Thomae, Andreas, Hauer, Joerg, Funk, Karsten, Lutz, Markus, Bauer, Wolfram, Willig, Rainer, Kuhlmann, Burkhard, Neul, Reinhard, Doering, Christian, Gomez, Udo-Martin, Wucher, Gerhard, Bischof, Udo, Franz, Jochen, Goetz, Siegbert, Fehrenbach, Michael
• Application Number:
  US10/473,004
• Publication Number:
  US 20040154398A1
• Time in Patent Office: Days
• 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

The present invention creates a micromechanical rotational rate sensor having a first Coriolis mass element (2a) and a second Coriolis mass element (2b) which are situated over a surface of a substrate (100); having an activating device by which the first Coriolis mass element (2a) and the second Coriolis mass element (2b) are able to have vibrations activated along a first axis (x); and having a detection device by which deflections of the first Coriolis mass elements (2a) and of the second Coriolis element (2b) are able to be detected along a second axis (y), which is perpendicular to the first axis (x), on the basis of a correspondingly acting Coriolis force; the first axis (x) and second axis (y) running parallel to the surface of the substrate (100);

the detecting device has a first detection mass device (3a, 3a′) and a second detection mass device (3b, 3b′); and the centers of gravity of the first Coriolis mass element (2a), the second Coriolis mass element (2b), the first detection mass device (3a, 3a′) and the second detection mass device (3b, 3b′) coincide at a common mass center of gravity (SP) when they are at rest.

Claims

1. A micromechanical rotational rate sensor having:

a first Coriolis mass element (2a) and a second Coriolis mass element (2b) which are situated over a surface of a substrate (100);

an activating device by which the first Coriolis mass element (2a) and the second Coriolis mass element (2b) is able to have vibrations activated along a first axis (x); and

a detecting device by which deflections of the first Coriolis mass elements (2a) and of the second Coriolis element (2b) are able to be detected along a second axis (y), which is perpendicular to the first axis (x), on the basis of a correspondingly acting Coriolis force;

the first axis (x) and second axis (y) running parallel to the surface of the substrate (100);

the detecting device having a first detection mass device (3a, 3a′

) and a second detection mass device (3b, 3b′

); and

the centers of gravity of the first Coriolis mass element (2a), the second Coriolis mass element (2b), the first detection mass device (3a, 3a′

) and the second detection mass device (3b, 3b′

) coinciding at a common mass center of gravity (SP) when they are at rest.

2. The micromechanical rotational rate sensor as recited in claim 1,

wherein the first detection mass device (3a, 3a′

) is connected to the first Coriolis mass element (2a) via first springs (7a, 7a′

) which are designed to be flexible along the first axis (x) and stiff along the second axis (y), and is connected to the substrate (100) via second springs (6a, 6a′

), which are designed to be stiff along the first axis (x) and flexible along the second axis (y); and

the second detection mass device (3b, 3b′

) is connected to the second Coriolis mass element (2b) via third springs (7b, 7b′

) which are designed to be flexible along the first axis (x) and stiff along the second axis (y), and is connected to the substrate (100) via fourth springs (6b, 6b′

), which are designed to be stiff along the first axis (x) and flexible along the second axis (y).

3. The micromechanical rotational rate sensor as recited in claim 1 or 2,

wherein the activating device has a first activating mass device (1a, 1a′

) and a second activating mass device (1b, 1b′

) and the centers of gravity of the first activating mass device (1a, 1a′

) and the second activating mass device (1b, 1b′

) also coincide at the common mass center of gravity (SP) when they are at rest.

4. The micromechanical rotational rate sensor as recited in claim 3, p1 wherein the first activating mass device (1a, 1a′

) has a first activating mass element (1a) and a second activating mass element (1a′

), and the second activating mass device (1b, 1b′

) has a third activating mass element (1b) and a fourth activating mass element (1b′

), which are able to be individually activated via a respective comb actuator (12a, 12b, 13a, 13b, 12a′

, 12b′

, 13a′

, 13b′

).

5. The micromechanical rotational rate sensor as recited in claim 4,

wherein the first and the second activating mass device (1a, 1a′

) are connected to the first Coriolis mass element (2a) via the fifth springs (8a, 8a′

) which are designed to be stiff along the first axis (x) and flexible along the second axis (y), and are connected to the substrate (100) via the sixth springs (5a, 5a′

), which are designed to be flexible along the first axis (x) and stiff along the second axis (y); and

the third and the fourth activating mass element (1b, 1b′

) are connected to the second Coriolis mass element (2b) via the seventh springs (8b, 8b′

) which are designed to be stiff along the first axis (x) and flexible along the second axis (y), and are connected to the substrate (100) via the eighth springs (5b, 5b′

), which are designed to be flexible along the first axis (x) and stiff along the second axis (y).

6. The rotational rate sensor as recited in one of the foregoing claims,

wherein the first Coriolis mass element (2a) has the shape of a closed polygonal frame, preferably of an essentially square frame.

7. The rotational rate sensor as recited in claim 6,

wherein the second Coriolis mass element (2b) is situated within the first Coriolis mass element (2a), and has a polygonal shape, preferably an essentially square shape.

8. The rotational rate sensor as recited in claim 2,

wherein the first Coriolis mass element (2a) and the second Coriolis mass element (2b) are able to have vibrations that are in phase opposition activated along a first axis (x) by the activating device;

and the first detection mass device (3a, 3a′

) and the second detection mass device (3b, 3b′

) are able to be deflected in various directions along the second axis y, based on the acting Coriolis force.

9. The rotational rate sensor as recited in one of the foregoing claims,

wherein the first detection mass device (3a, 3a′

) has a first detection mass element (3a) and a second detection mass element (3a′

), and the second detection mass device (3b, 3b′

) has a third detection mass element (3b) and a fourth detection mass element (3b′

), which each have a plurality of fingers (F), which are situated along the second axis (y); and

at the fingers (F), movable electrodes (16a, 16b, 16a′

, 16b′

) are provided, which cooperate with the electrodes (14, 14′

), that are firmly anchored to the substrate (100), to detect the deflections.

10. The rotational rate sensor as recited in one of the preceding claims 4 through 9,

wherein the first activating mass element (1a) and the third activating mass element (1b), as well as the second activating mass element (1a′

) and the fourth activating mass element (1b′

) are coupled to one another pairwise by a connecting spring (9, 9′

) in each case, which is designed to be flexible along the first axis (x) and preferably stiff along the second axis (y).

11. The rotational rate sensor as recited in one of the preceding claims 9 or 10,

wherein the first detection mass element (3a) and the third detection mass element (3b), as well as the second detection mass element (3a′

) and the fourth detection mass element (3b′

) are coupled pairwise to one another by a respective connecting spring (10, 10′

) in each case, which is preferably designed to be stiff along the first axis (x) and flexible along the second axis (y).

12. The rotational rate sensor as recited in one of the foregoing claims,

wherein a mechanical coupling is provided along the x axis and along the y axis by a coupling spring device between the Coriolis mass elements (2a, 2b), the coupling spring device being designed to be flexible along the x axis and along the y axis.