Common centroid micromachine driver

• US 7,478,557 B2
• Filed: 09/30/2005
• Issued: 01/20/2009
• Est. Priority Date: 10/01/2004
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Geen, John A.
• Primary Examiner(s): Kwok; Helen C.
• Application Number:
  US11/241,754
• Publication Number:
  US 20060144174A1
• Time in Patent Office: 1,208 Days
• Field of Search: 735/040.4, 735/041.2, 735/041.4, 735/143.2, 735/143.6, 735/143.8
• US Class Current: 73/504.14
• CPC Class Codes: G01C 19/5719 using planar vibrating masses driven in a translation vibration along an axis
• CPC Class Codes: Y10T 74/12 Gyroscopes

Abstract

A drive arrangement for a micromachine includes a plurality of fixed electrodes arranged so as to have a common centroid.

Claims

1. Apparatus comprising:

a resonator mass movable along an axis; and

a drive arrangement for moving the mass along the axis, the drive arrangement having a plurality of fixed electrodes operably coupled so as to have a common centroid, wherein the drive arrangement comprises;

a first fixed electrode oriented in a first direction;

a second fixed electrode adjacent to the first fixed electrode and oriented in a second direction opposite the first direction;

a third fixed electrode opposite the first fixed electrode and oriented in the second direction; and

a fourth fixed electrode opposite the second fixed electrode and oriented in the first direction, wherein the first and fourth fixed electrodes operate in phase with one another, and wherein the second and third fixed electrodes operate in phase with one another and in anti-phase with the first and fourth fixed electrodes.

2. Apparatus according to claim 1, wherein each fixed electrode includes a plurality of fixed fingers that interdigitate with corresponding drive fingers of the mass such that there is a region in which the fixed fingers overlap with the drive fingers, and wherein the fixed electrodes are arranged such that the center lines of the overlap regions associated with adjacent fixed electrodes are co-linear and parallel to the axis.

3. Apparatus according to claim 1, wherein the drive arrangement further comprises:

a fifth fixed electrode adjacent to the second fixed electrode and oriented in the second direction;

a sixth fixed electrode opposite the fifth fixed electrode and oriented in the first direction;

a seventh fixed electrode adjacent to the fifth fixed electrode and oriented in the first direction; and

an eighth fixed electrode opposite the seventh fixed electrode and oriented in the second direction, wherein the first, fourth, sixth, and seventh fixed electrodes operate in phase with one another, and wherein the second, third, fifth, and eighth fixed electrodes operate in phase with one another and in anti-phase with the first, fourth, sixth, and seventh fixed electrodes.

4. Apparatus according to claim 1, wherein the drive arrangement further comprises:

a fifth fixed electrode adjacent to the second fixed electrode and oriented in the first direction; and

a sixth fixed electrode opposite the fifth fixed electrode and oriented in the second direction, wherein the first, fourth, and fifth fixed electrodes operate in phase with one another, and wherein the second, third, and sixth fixed electrodes operate in phase with one another and in anti-phase with the first, fourth, and fifth fixed electrodes.

5. Apparatus according to claim 4, wherein the first, third, fifth, and sixth electrodes are substantially identical to one another, and wherein the second and fourth fixed electrodes are substantially identical to one another and are approximately twice the size of the first, third, fifth, and sixth fixed electrodes.

6. Apparatus according to claim 1, wherein each fixed electrode includes at least two outer sections anchored to an underlying substrate and a middle section suspended from the outer sections so as to float above the underlying substrate.

7. Apparatus according to claim 6, wherein the outer sections are anchored using at least one of an elongated anchor and a plurality of anchors.

8. Apparatus according to claim 1, wherein the resonator mass is suspended within a frame that is movably coupled to an underlying substrate.

9. Apparatus comprising a plurality of resonator masses, each resonator mass associated with at least one drive arrangement for moving the mass along an axis, each drive arrangement having a plurality of fixed electrodes operably coupled so as to have a common centroid, wherein the at least one drive arrangement comprises:

a first fixed electrode oriented in a first direction;

a second fixed electrode adjacent to the first fixed electrode and oriented in a second direction opposite the first direction;

a third fixed electrode opposite the first fixed electrode and oriented in the second direction; and

a fourth fixed electrode opposite the second fixed electrode and oriented in the first direction, wherein the first and fourth fixed electrodes operate in phase with one another, and wherein the second and third fixed electrodes operate in phase with one another and in anti-phase with the first and fourth fixed electrodes.

10. Apparatus according to claim 9, wherein each fixed electrode includes a plurality of fixed fingers that interdigitate with corresponding drive fingers of the mass such that there is a region in which the fixed fingers overlap with the drive fingers, and wherein the fixed electrodes of each drive arrangement are arranged such that the center lines of the overlap regions associated with adjacent fixed electrodes are co-linear and parallel to the axis.

11. Apparatus according to claim 9, wherein the drive arrangement further comprises:

a fifth fixed electrode adjacent to the second fixed electrode and oriented in the second direction;

a sixth fixed electrode opposite the fifth fixed electrode and oriented in the first direction;

a seventh fixed electrode adjacent to the fifth fixed electrode and oriented in the first direction; and

an eighth fixed electrode opposite the seventh fixed electrode and oriented in the second direction, wherein the first, fourth, sixth, and seventh fixed electrodes operate in phase with one another, and wherein the second, third, fifth, and eighth fixed electrodes operate in phase with one another and in anti-phase with the first, fourth, sixth, and seventh fixed electrodes.

12. Apparatus according to claim 9, wherein the drive arrangement further comprises:

a fifth fixed electrode adjacent to the second fixed electrode and oriented in the first direction; and

a sixth fixed electrode opposite the fifth fixed electrode and oriented in the second direction, wherein the first, fourth, and fifth fixed electrodes operate in phase with one another, and wherein the second, third, and sixth fixed electrodes operate in phase with one another and in anti-phase with the first, fourth, and fifth fixed electrodes.

13. Apparatus according to claim 12, wherein the first, third, fifth, and sixth electrodes are substantially identical to one another, and wherein the second and fourth fixed electrodes are substantially identical to one another and are approximately twice the size of the first, third, fifth, and sixth fixed electrodes.

14. Apparatus according to claim 9, wherein each fixed electrode includes at least two outer sections anchored to an underlying substrate and a middle section suspended from the outer sections so as to float above the underlying substrate.

15. Apparatus according to claim 14, wherein the outer sections are anchored to the underlying substrate using at least one of an elongated anchor and a plurality of anchors.

16. Apparatus according to claim 9, wherein the plurality of resonator masses includes two masses operably coupled to resonate in anti-phase with one another.

17. Apparatus according to claim 16, wherein each of the resonator masses is split into two interconnected lobes, and wherein each lobe is associated with a drive arrangement.

18. Apparatus according to claim 9, wherein the plurality of resonator masses are suspended within a frame that is movably coupled to an underlying substrate.