Method for Detecting Accelerations and Rotation Rates, and MEMS Sensor

• US 20160003617A1
• Filed: 09/14/2015
• Published: 01/07/2016
• Est. Priority Date: 03/31/2009
• Status: Active Grant

• Current Assignee: Hanking Electronics Hongkong Company Limited
• Original Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Inventors: Rocchi, Alessandro
• Granted Patent: US 9,664,515 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01C 19/574 the devices having two sensing masses in anti-phase motion
• CPC Class Codes: G01C 19/5747 each sensing mass being connected to a driving mass, e.g. driving frames
• CPC Class Codes: G01C 19/5755 the devices having a single sensing mass
• CPC Class Codes: G01C 19/5762 the sensing mass being connected to a driving mass, e.g. driving frames
• CPC Class Codes: G01P 15/097 by vibratory elements
• CPC Class Codes: G01P 15/14 by making use of gyroscopes gyroscopes per se G01C19/00
• CPC Class Codes: G01P 15/18 in two or more dimensions

Abstract

The invention concerns a MEMS sensor and a method for detecting accelerations along, and rotation rates about, at least one, preferably two of three mutually perpendicular spatial axes x, y and z by means of a MEMS sensor (1), wherein at least one driving mass (6; 6.1, 6.2) and at least one sensor mass (5) are moveably arranged on a substrate (2) and the at least one driving mass (6; 6.1, 6.2) is moved relative to the at least one sensor mass (5) in oscillation at a driving frequency and when an external acceleration of the sensor occurs, driving mass/es (6; 6.1, 6.2) and sensor mass/es (5) are deflected at an acceleration frequency and, when an external rotation rate of the sensor (1) occurs, are deflected at a rotation rate frequency, and the acceleration frequency and rotation rate frequency are different. At the MEMS-sensor the driving mass/es (6; 6.1, 6.2) and sensor mass/es (5) are arranged on the substrate (2), and are balanced in the resting state by means of at least one of the anchors (3). In the driving mode the driving mass/es (6; 6.1, 6.2), when vibrating in oscillation about this at least one anchor (3), generate/s an imbalance of the driving mass/es (6; 6.1, 6.2) and the sensor mass/es (5) with respect to this at least one anchor (3), and the sensor elements detect deflections of the driving and sensor masses, due to torques and Coholis forces generated, with an acceleration frequency and/or a rotation rate frequency.

Claims

1. A micro-electro-mechanical-system (MEMS) sensor for detecting rotational movements about at least one of three mutually perpendicular spatial axes, comprising:

a substrate;

at least one driving mass that oscillates in a plane parallel to the substrate;

at least one sensing mass coupled to the least one driving mass via connecting springs;

at least one anchor secured to the substrate and at least one anchor spring coupled to the at least one driving mass or the at least one sensing mass;

sensing elements for sensing rotation of the MEMS sensor; and

at least one drive element for driving the at least one driving mass relative to the at least one sensing mass at a driving frequency,

wherein the at least one driving mass generates an imbalance of the at least one driving mass and the at least one sensing mass with respect to the at least one anchor during operation.

2. A MEMS sensor as recited in claim 1, wherein the at least one driving mass and the at least one sensing mass deflect at a frequency that is equal to the driving frequency when the MEMS sensor is accelerated.

3. A MEMS sensor as recited in claim 1, wherein the at least one driving mass and the at least one sensing mass deflect at a frequency that is higher than the driving frequency when the MEMS sensor is rotated.

4. A MEMS sensor as recited in claim 1, wherein the at least one anchor spring is directly connected to the at least one driving mass and allows the at least one driving mass to move along a first axis.

5. A MEMS sensor as recited in claim 4, wherein the at least one anchor spring allows the at least one driving mass to rotate along second and third axes.

6. A MEMS sensor as recited in claim 1, wherein the at least one anchor is a central anchor.

7. A MEMS sensor as recited in claim 1, wherein the connecting springs move along a first axis only, further comprising:

sensor springs coupled to the at least one driving mass and the at least one sensing mass and allow the at least one sensing mass to move along second and third axes relative to the at least one driving mass.

8. A MEMS sensor as recited in claim 7, wherein the at least one anchor spring is coupled to the at least one sensing mass.

9. A MEMS sensor as recited in claim 8, wherein the at least one driving mass includes first and second driving masses and the first driving mass is disposed outside the at least one sensing mass and the second driving mass is dispose inside the at least one sensing mass.

10. A MEMS sensor as recited in claim 9, wherein the first one of the connecting springs moves along the first axis and is coupled to the first driving mass and a second one of the connecting springs moves along the second axis and is coupled to the second driving mass.

11. A MEMS sensor as recited in claim 8, wherein a number of the at least one anchor spring is same as a number of the at least one anchor and wherein each of the at least one anchor spring is coupled to a corresponding one of the at least one anchor.

12. A MEMS sensor as recited in claim 8, wherein the at least one driving mass includes four driving masses disposed outside the sensing mass.

13. A MEMS sensor as recited in claim 12, wherein the driving elements drive a first one of the four driving masses at a first driving frequency along the first axis and a second one of the four driving masses at a second driving frequency along the second axis.

14. A MEMS sensor as recited in claim 12, wherein the at least one anchor is a central anchor.

15. A MEMS sensor as recited in claim 14, wherein the at least one sensing mass rotates and pivots about an axis passing through the central anchor.

16. A MEMS sensor as recited in claim 1, wherein the sensing elements measure a movement of the at least one driving mass.

17. A MEMS sensor as recited in claim 1, wherein the sensing elements measure a movement of the at least one sensing mass.

18. A MEMS sensor as recited in claim 1, wherein the at least one anchor spring allows the sensing mass to rotate along a third axis.

19. A MEMS sensor as recited in claim 1, wherein the connecting springs cause the at least one driving mass rigidly coupled to the at least one sensing mass along second and third axes.