MEMS DEVICES SENSING BOTH ROTATION AND ACCELERATION

• US 20120297873A1
• Filed: 05/23/2011
• Published: 11/29/2012
• Est. Priority Date: 05/23/2011
• Status: Active Grant

• Current Assignee: Senodia Technologies Company Limited
• Original Assignee: Senodia Technologies Company Limited
• Inventors: Zou, Bo, Luo, Hao
• Granted Patent: US 9,010,184 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5762 the sensing mass being connected to a driving mass, e.g. driving frames
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• 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

A MEMS device comprises a proof mass suspended above a substrate, one or more driving combs, and one or more sensing combs. During operation, a DC actuating potential in series with an AC modulation potential is applied to the proof mass, and an AC actuating potential is applied to the one or more driving combs such that the proof mass moves in an oscillatory manner. An inertial sensing system further comprises a sensing element configured to detect a rotation information coupled with an AC signal and an acceleration information coupled with a DC signal.

Claims

1. A method of sensing acceleration and rotation, comprising:

providing an MEMS device, the MEMS device comprising;

one or more proof masses suspended above a substrate;

one or more driving combs; and

one or more sensing combs;

applying a DC actuating potential in series with an AC modulation potential to the one or more proof masses;

applying an AC actuating potential to the one or more driving combs such that the one or more proof masses move in an oscillatory manner during operation.

2. The method of claim 1, wherein:

the AC modulation potential have a first frequency,

the AC actuating potential has a second frequency, and

the first frequency is higher than the second frequency.

3. The method of claim 2, wherein:

the first frequency is about 100 K Hz to about 10 M Hz, and

the second frequency is about 1 K Hz to 100 K Hz.

4. The method of claim 1, wherein the DC actuating and the AC modulation potential are large enough to move the one or more proof masses by electrostatic force.

5. The method of claim 4, wherein the DC actuating potential is higher than about 5 Volts.

6. The method of claim 1, wherein when rotation and acceleration are applied to the MEMS device, capacitance of the one or more driving combs changes.

7. The method of claim 1, further comprising demodulating, at the first frequency, an output signal comprising information of the capacitance change of the one or more driving combs.

8. The method of claim 7, further comprising separating the acceleration information from the demodulated output signal.

9. The method of claim 8, wherein during the step of separating the acceleration information from the demodulated output signal, a first low pass filter is used to remove AC components in the output signal to separate the acceleration information from the output signal.

10. The method of claim 7, further comprising separating the rotation information from the demodulated output signal.

11. The method of claim 10, wherein during the step of separating the rotation information from the demodulated output signal:

a band pass filter is used to remove DC signal and components having frequency higher than the second frequency in the demodulated output signal,

a demodulator is used to demodulate, at the second frequency, an output of the band bass filter, and

a second low pass filter is used to remove high frequency harmonics in an output of the demodulator.

13. The inertial sensing system of claim 1, further comprising a sensing element configured to detect a rotation information coupled with an AC signal and an acceleration information coupled with a DC signal.

14. The inertial sensing system of claim 1, wherein:

the AC modulation potential signal have a first frequency,

the AC actuating potential has a second frequency, and

the first frequency is higher than the second frequency.

15. The inertial sensing system of claim 14, wherein:

the first frequency is about 100 K Hz to about 10 M Hz, and

the second frequency is about 1 K Hz to 100 K Hz.

16. The inertial sensing system of claim 1, wherein the DC actuating potential and the AC modulation potential are large enough to move the proof mass by electrostatic force.

17. The inertial sensing system of claim 16, wherein the DC actuating potential is higher than about 5 Volts.

12. An inertial sensing system comprising an MEMS device, wherein:

the MEMS device comprises a proof mass suspended above a substrate, one or more driving combs, and one or more sensing combs; and

during operation, a DC actuating potential in series with an AC modulation potential is applied to the proof mass, and an AC actuating potential is applied to the one or more driving combs such that the proof mass moves in an oscillatory manner.

18. An inertial sensing device, comprising:

one or more proof masses;

one or more moving frames;

one or more first stationary anchors attached to a substrate;

one or more driving combs, each of the one of more driving combs comprising a plurality first comb fingers and a plurality of second comb fingers; and

one or more sensing combs, each of the one of more sensing combs comprising a plurality third comb fingers and a plurality of fourth comb fingers,

wherein;

each of the one or more moving frames is attached to a corresponding one of the one or more proof masses by a corresponding one of first springs,

each of the one or more moving frames is attached, via a corresponding one of second springs, to a corresponding one of the one or more first stationary anchors,

the plurality of first comb fingers are attached directly to a corresponding one of the one or more moving frames, and

the plurality of fourth comb fingers are attached, directly or via a second movable frame to the corresponding one of the one or more proof masses, wherein the second movable frame is attached to the corresponding one of the one or more proof masses via a corresponding one of third springs.

19. An inertial sensing device of claim 18, further comprising:

one or more second stationary anchors attached to the substrate, wherein the plurality of second comb fingers are attached directly to a corresponding one of the one or more second stationary anchors; and

one or more third stationary anchors attached to the substrate, wherein the plurality of third comb fingers are attached directly to a corresponding one of the one or more third stationary anchors.