Error correction in acceleration-sensing devices

• US 9,027,402 B2
• Filed: 04/30/2010
• Issued: 05/12/2015
• Est. Priority Date: 04/30/2010
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Homeijer, Brian D., Bicknell, Robert N.
• Primary Examiner(s): Macchiarolo, Peter
• Assistant Examiner(s): KOLB, NATHANIEL J
• Application Number:
  US13/643,883
• Publication Number:
  US 20130036789A1
• Time in Patent Office: 1,838 Days
• Field of Search: 735/141.8
• US Class Current: 73/514.18
• CPC Class Codes: G01P 15/125 by capacitive pick-up
• CPC Class Codes: G01P 2015/0814 for translational movement of the mass, e.g. shuttle type
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups

Abstract

An acceleration-sensing device having error correction includes a stator having at least one conductor affixed to a surface and a proof mass having a first conductor affixed at a first location relative to the at least one conductor affixed to a surface of the stator. The proof mass includes a second conductor affixed at a second location relative to the at least one conductor affixed to a surface of the stator, wherein an excitation signal applied to the first conductor of the proof mass brings about a force on the proof mass in the plane of motion of the proof mass that is substantially equally opposed by a force resulting from an excitation signal applied to the second conductor of the proof mass in the plane of motion of the proof mass.

Claims

1. An acceleration-sensing device having error correction, comprising:

a stator having at least one conductor affixed to a surface; and

a proof mass having a first conductor affixed at a first location relative to the at least one conductor affixed to a surface of the stator, the proof mass having a second conductor affixed at a second location relative to the at least one conductor affixed to a surface of the stator, wherein

an excitation signal applied to the first conductor of the proof mass brings about a force on the proof mass in the plane of motion of the proof mass that is substantially equally opposed by a force resulting from the excitation signal applied to the second conductor of the proof mass in the plane of motion of the proof mass.

2. The acceleration-sensing device of claim 1, wherein the excitation signal is a periodic waveform, and wherein acceleration is measured by way of determining the amplitude of a signal induced by the excitation signal on the at least one conductor affixed to a surface of the stator.

3. The acceleration-sensing device of claim 2, where in the excitation signal is a sinusoidal waveform.

4. The acceleration-sensing device of claim 1, wherein the first conductor and the second conductor of the proof mass are located at a first side of a gap, and wherein the at least one conductor affixed to a surface of the stator is positioned at a second side of the gap.

5. The acceleration-sensing device of claim 4, wherein the plane of motion of the proof mass moves is lengthwise relative to the gap.

6. The acceleration-sensing device of claim 4, wherein the ratio of the inter-conductor spacing to the gap width approximates 1.

7. The acceleration-sensing device of claim 1, further comprising at least one spring that generates a restoring force to return the proof mass to a neutral position under quiescent conditions.

8. A method of correcting an error in an acceleration-sensing device, comprising:

generating an excitation signal on at least a first and a second conductor affixed to a proof mass;

coupling, onto at least one conductor affixed to a stator, a signal from the first conductor affixed to the proof mass; and

coupling, onto the at least one conductor, a signal from the second conductor affixed to the proof mass, wherein

the signal coupled from the first conductor affixed to the proof mass causes the proof mass to experience a force in a first direction in a plane of motion of the proof mass, and wherein

the signal coupled from the second conductor affixed to the proof mass causes the proof mass to experience a force in a direction substantially equal and opposite to the force in the first direction.

9. The method of claim 8, wherein the signal coupled from the first conductor affixed to the proof mass induces a first current on the at least one conductor affixed to the stator, and wherein

the signal coupled from the second conductor affixed to the proof mass induces a second current on the at least one conductor affixed to the stator.

10. The method of claim 8, wherein the signal from the first conductor affixed to the proof mass and wherein the signal from the second conductor affixed to the proof mass are coupled across an approximately 1μ

gap to the stator.

11. The method of claim 10, wherein the first direction is perpendicular to the gap.

12. The method of claim 11, wherein the force in the first direction is brought about by an electric field that acts between the first conductor affixed to the proof mass and the at least one conductor affixed to the stator.

13. The method of claim 8, wherein the excitation signal is a sinusoidal waveform, and wherein the method further comprises demodulating signals from the at least one conductor to determine the acceleration undergone by the proof mass.

14. The method of claim 8, wherein the excitation signal is a square wave, and wherein the method further comprises demodulating signals from the at least one conductor to determine the acceleration undergone by the proof mass.

15. The method of claim 14, further comprising restoring the proof mass to a quiescent position when the proof mass is not undergoing acceleration and when the excitation signal has been removed.