MEMS enhanced capacitive pick-off and electrostatic rebalance electrode placement

• US 20040160232A1
• Filed: 02/18/2003
• Published: 08/19/2004
• Est. Priority Date: 02/18/2003
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Leonardson, Ronald B., Yue, Aiwu
• Granted Patent: US 6,841,992 B2
• Time in Patent Office: Days
• US Class Current: 324/660
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 15/131 with electrostatic counterbalancing means
• 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

A Micro Electro-Mechanical System (MEMS) acceleration sensing device, formed of a sensing element having first and second substantially planar and parallel spaced apart opposing surfaces and being suspended for pendulous motion about a hinge axis oriented along a minor axis of the sensing element; and one or more substrates each having a face spaced from one of the opposing surfaces of the sensing element, each of the substrates having pluralities of electrodes arranged substantially crosswise to the hinge axis of the sensing element symmetrically to a longitudinal axis of the sensing device and forming respective first and second capacitors with the moveable sensing element. Each of the one or more substrates optionally including a clearance relief for extending the rotational range of motion of the sensing element.

Claims

1. A Micro Electro-Mechanical System (MEMS) sensor, comprising:

a sensing element suspended for motion relative to a rotational axis,

one or more stationary substrates spaced away from the sensing element; and

a plurality of capacitors formed by the sensing element and the substrate, the capacitors being arranged substantially crosswise to the rotational axis of the sensing element.

2. The sensor of claim 1 wherein each of the capacitors further comprises one or more electrodes formed on a surface of the substrate facing the sensing element.

3. The sensor of claim 1 wherein each of the plurality of capacitors further comprises an electrode assigned for operation as one of an excitation electrode and a feedback electrode.

4. The sensor of claim 1 wherein each of the plurality of capacitors further comprises an electrode having a feedback signal superimposed on an excitation signal.

5. The sensor of claim 1 wherein the stationary substrate further comprises first and second surfaces spaced different distances from the sensing element, a first of the plurality of capacitors being formed by the sensing element and the first surface of the substrate, and a second of the plurality of capacitors being formed by the sensing element and the second surface of the substrate.

6. The sensor of claim 5 wherein the first surface further comprises a pair of surfaces spaced apart on opposite sides of the second surface.

7. The sensor of claim 5 wherein the stationary substrate further comprises a clearance area corresponding to a portion of the sensing element distal from the hinge axis, the clearance area being offset from one of the first and second surfaces relative to the sensing element.

8. The sensor of claim 5 wherein the stationary substrate further comprises a clearance area corresponding to a portion of the sensing element distal from the hinge axis, the clearance area being offset from both of the first and second surfaces relative to the sensing element.

9. The sensor of claim 5 wherein the stationary substrate further comprises a clearance area corresponding to a portion of the sensing element distal from the hinge axis, the clearance area being substantially coplanar with one of the first and second surfaces that is spaced farther from the sensitive element.

10. A Micro Electro-Mechanical System (MEMS) acceleration sensing device, comprising:

a sensing element suspended for motion about a hinge axis; and

a pair of substantially planar substrates spaced on opposite sides of the sensing element, each of the substrates having first and second electrodes arranged in elongated patterns oriented substantially crosswise to the hinge axis of the sensing element.

11. The device of claim 10 wherein one or both of the first and second electrodes further comprises a plurality of electrodes arranged in the elongated patterns.

12. The device of claim 10 wherein the first and second electrodes are arranged in substantially contiguous first and second patterns.

13. The device of claim 10 wherein the first and second electrodes are arranged in relatively staggered first and second patterns.

14. The device of claim 10 wherein a surface of each substrate facing toward the sensing element further comprises a three-dimensional structure with the first and second electrodes being spaced on the structure with lesser and greater distances from the sensing element.

15. The device of claim 14 wherein the three-dimensional structure of each substrate further comprises a surface portion positioned opposite from a portion of the sensing element distal from the hinge axis and being spaced at a greater distance from the sensing element than one of the first and second electrodes.

16. The device of claim 15 wherein the surface portion of the substrate corresponding to a distal portion of the sensing element further comprises a surface portion that is substantially coplanar with the structure spaced at the greater distance from the sensing element.

17. The device of claim 15 wherein the surface portion of the substrate corresponding to a distal portion of the sensing element further comprises a surface portion that is inclined away from the sensing element.

18. The device of claim 15 wherein the surface portion of the substrate positioned opposite from a distal portion of the sensing element further comprises a surface portion that is spaced at a greater distance from the sensing element than both of the first and second electrodes.

19. The device of claim 14 wherein a portion of each substrate positioned opposite from a portion of the sensing element distal from the hinge axis is truncated from the three-dimensional structure of each substrate.

20. A Micro Electro-Mechanical System (MEMS) capacitive acceleration sensing device, comprising:

a sensing element having first and second substantially planar and parallel spaced apart opposing surfaces and being suspended for pendulous motion about a hinge axis oriented along a shorter axis of the sensing element; and

one or more substantially planar substrates each having a face spaced away from one of the opposing surfaces of the sensing element, each of the substrates having first and second pluralities of electrodes arranged in elongated patterns oriented substantially crosswise to the hinge axis of the sensing element and forming respective first and second capacitors with sensing element.

21. The acceleration sensing device of claim 20 wherein the face of each of the one or more substrates further comprises a three-dimensional structure having substantially planar and parallel trough and mesa surface oriented crosswise to the hinge axis of the sensing element, the trough surface being spaced more distantly than the mesa surface from the surface of the sensing element, and the first and second pluralities of electrodes being arranged respectively on the trough and mesa surfaces.

22. The acceleration sensing device of claim 21 wherein the trough surfaces further comprise a pair of substantially coplanar trough surfaces arranged symmetrically on opposite sides of a single mesa surface.

23. The acceleration sensing device of claim 21 wherein the mesa surfaces further comprise a pair of substantially coplanar mesa surfaces arranged symmetrically on opposite sides of a single trough surface.

24. The acceleration sensing device of claim 21 wherein the face of each of the substrates further comprises a clearance relief surface positioned opposite from a moveable portion of the sensing element remote from the hinge axis, the clearance relief surface being substantially coplanar with and interconnected with the trough surface and sized to clear the moveable portion of the sensing element.

25. The acceleration sensing device of claim 21 wherein the face of each of the substrates further comprises a clearance relief surface positioned opposite from a moveable portion of the sensing element remote from the hinge axis, the clearance relief surface being spaced more distantly than the trough and mesa surfaces from the surface of the sensing element and being sized to clear the moveable portion of the sensing element.

26. The acceleration sensing device of claim 21 wherein the face of each of the substrates further comprises a clearance relief surface positioned opposite from a moveable portion of the sensing element remote from the hinge axis, the clearance relief surface being inclined away from the surface of the sensing element and being sized to clear the moveable portion of the sensing element.

27. The acceleration sensing device of claim 21 wherein a portion of each of the substrates is truncated in an area positioned opposite from a moveable portion of the sensing element remote from the hinge axis, the truncated portion being sized to clear the moveable portion of the sensing element.