Rotating motion sensor

• US 8,393,214 B2
• Filed: 08/07/2007
• Issued: 03/12/2013
• Est. Priority Date: 08/23/2006
• Status: Active Grant

• Current Assignee: Epcos AG (TDK Corporation)
• Original Assignee: Epcos AG (TDK Corporation)
• Inventors: Ruile, Werner, Leidl, Anton
• Primary Examiner(s): Patel, Harshad R
• Application Number:
  US12/438,251
• Publication Number:
  US 20090255337A1
• Time in Patent Office: 2,044 Days
• Field of Search: None
• US Class Current: 73/514.12
• CPC Class Codes: G01C 19/5698 using acoustic waves, e.g. surface acoustic wave gyros

Abstract

A rotating motion sensor includes at least one electroacoustic resonator to stimulate a surface acoustic wave. The at least one electroacoustic resonator is configured so that rotation of the at least one electroacoustic resonator about an axis of rotation causes a change in resonance frequency of the at least one electroacoustic resonator. The at least one electroacoustic resonator includes oscillating structures configured to oscillate in a first direction that is a direction of propagation of the surface acoustic wave and/or a second direction that is transverse to the direction of propagation of the surface acoustic wave.

Claims

1. A rotating motion sensor comprising:

an electroacoustic resonator comprising a transducer, the transducer comprising a piezoelectric substrate and an array of electrode strips on the piezoelectric substrate, the electroacoustic resonator to stimulate a surface acoustic wave, the electroacoustic resonator comprising oscillating structures configured to oscillate in one or both of;

(i) a first direction that is along a direction of propagation of the surface acoustic wave, and (ii) a second direction that is transverse to the direction of propagation of the surface acoustic wave, at least part of the oscillating structures being on the electrode strips and/or between the electrode strips;

wherein the electroacoustic resonator is configured so that rotation of the electroacoustic resonator about an axis of rotation causes a change in resonance frequency of the electroacoustic resonator.

2. The rotating motion sensor of claim 1, wherein the oscillating structures are tower-shaped.

3. The rotating motion sensor of claim 1, wherein the oscillating structures extend further in the first direction than in the second direction.

4. The rotating motion sensor of claim 1, wherein each of the oscillating structures has a height of at least λ

, where λ

is a wavelength of the surface acoustic wave.

5. The rotating motion sensor of claim 1, wherein the surface acoustic wave is a shear wave.

6. The rotating motion sensor of claim 1, wherein the surface acoustic wave is a Rayleigh wave.

7. The rotating motion sensor of claim 1, wherein, in the second direction, at least some of the oscillating structures are arranged linearly.

8. The rotating motion sensor of claim 1, wherein each of the oscillating structures comprises at least two layers, the at least two layers comprising an upper layer and a lower layer, the upper layer being further from a substrate below the oscillating structures than the lower layer;

and

wherein the upper layer comprises a first material and the lower layer comprises a second material, the first material having a higher density than the second material.

9. The rotating motion sensor of claim 1, wherein oscillation of the oscillating structures is characterized by a resonance curve;

and

wherein an operating frequency range for the rotating motion sensor is within a bandwidth that substantially corresponds to a half height of the resonance curve.

10. The rotating motion sensor of claim 1, wherein at least two of the oscillating structures have different geometries.

11. The rotating motion sensor of claim 1, wherein the oscillating structures comprise at least one layer that is not electrically conductive.

12. The rotating motion sensor of claim 1, wherein the oscillating structures comprise at least one layer that is electrically conductive.

13. The rotating motion sensor of claim 1, wherein the electroacoustic resonator is configured so that rotation of the electroacoustic resonator about an axis of rotation causes a change in propagation velocity of the surface acoustic wave.

14. The rotating motion sensor of claim 1, wherein the oscillating structures have mechanical parameters that are designed to define a maximum oscillation amplitude of the electroacoustic resonator.

15. The rotating motion sensor of claim 1, wherein the different regions comprise an inner region and an edge region;

and

wherein the edge region has a lower density of oscillating structures than does the inner region.

16. The rotating motion sensor of claim 15, wherein the rotating motion sensor comprises different regions;

wherein there are different densities of oscillating structures in the different regions.

17. A rotating motion sensor comprising:

at least one electroacoustic resonator to stimulate a surface acoustic wave, the at least one electroacoustic resonator comprising;

oscillating structures configured to oscillate in one or both of;

(i) a first direction that is a direction of propagation of the surface acoustic wave, and (ii) a second direction that is transverse to the direction of propagation of the surface acoustic wave;

wherein the at least one electroacoustic resonator is configured so that rotation affects operation of the at least one electroacoustic resonator;

wherein at least two of the oscillating structures have different geometries;

wherein at least two of the oscillating structures comprise different layer structures; and

wherein the at least one electroacoustic resonator comprises different regions, the different regions comprising different densities of oscillating structures.

18. A rotating motion sensor comprising:

at least one electroacoustic resonator to stimulate a surface acoustic wave, the at least one electroacoustic resonator comprising oscillating structures configured to oscillate in one or both of;

(i) a first direction that is along a direction of propagation of the surface acoustic wave, and (ii) a second direction that is transverse to the direction of propagation of the surface acoustic wave;

wherein each of the oscillating structures comprises at least two layers, the at least two layers comprising an upper layer and a lower layer, the upper layer being further from a substrate below the oscillating structures than the lower layer;

wherein the upper layer comprises a first material and the lower layer comprises a second material, the first material having a higher density than the second material; and

wherein the at least one electroacoustic resonator is configured so that rotation of the at least one electroacoustic resonator about an axis of rotation causes a change in resonance frequency of the at least one electroacoustic resonator.

19. A rotating motion sensor comprising:

at least one electroacoustic resonator to stimulate a surface acoustic wave, the at least one electroacoustic resonator comprising oscillating structures configured to oscillate in one or both of;

(i) a first direction that is along a direction of propagation of the surface acoustic wave, and (ii) a second direction that is transverse to the direction of propagation of the surface acoustic wave;

wherein the at least one electroacoustic resonator is configured so that rotation of the at least one electroacoustic resonator about an axis of rotation causes a change in resonance frequency of the at least one electroacoustic resonator;

wherein oscillation of the oscillating structures is characterized by a resonance curve; and

wherein an operating frequency range for the rotating motion sensor is within a bandwidth that substantially corresponds to a half height of the resonance curve.