Thin film micromechanical resonator gyro

• US 5,438,231 A
• Filed: 08/23/1993
• Issued: 08/01/1995
• Est. Priority Date: 08/23/1993
• Status: Expired due to Term

• Current Assignee: Rockwell International Corporation
• Original Assignee: Rockwell International Corporation
• Inventors: Khoshnevisan, Mohsen, Motamedi, Manouchehr E., Neurgaonkar, Ratnakar R.
• Primary Examiner(s): BUDD, MARK OSBORNE
• Application Number:
  US08/110,524
• Time in Patent Office: 708 Days
• Field of Search: 310/321, 310/323, 310/334, 310/370, 310/366, 310/311, 310/330-332
• US Class Current: 310/321
• CPC Class Codes: G01C 19/5621 the devices involving a micromechanical structure
• CPC Class Codes: H03H 9/21 Crystal tuning forks

Abstract

A method to fabricate a tuning fork resonator gyro which uses non-piezoelectric substrate structure is proposed. The tuning fork structure can be effectively rendered piezoelectric for activation and sensing by thin film deposition of a piezoelectric material. Electrical excitation of the piezo film excites vibrations in the structure of the drive tuning fork, and the gyro signal generated due to rotation can be picked up from the piezo film on the signal tuning fork. Most piezoelectric films have a much higher piezoelectric coupling than crystalline quartz, the material used in the prior art. The piezoelectric films on mechanically hard non-piezoelectric substrates are simpler for fabrication, electroding, and have a number of other advantages over the prior art. Fabrication of the tuning fork structures can be done more simply than the prior art, and deposition of the piezo films can be accomplished by sol-gel, or other thin film techniques. The proposed methods thus provide considerable flexibility to separately optimize the resonator structure in terms of the physical and mechanical properties of the structure, the required piezoelectric properties, and methods for fabrication, processing and low cost manufacturing of resonator gyros.

Claims

1. A thin film micromechanical resonator, comprising:

(a) a non-piezoelectric tuning fork having two tines;

(b) a piezoelectric thin film disposed on each tine of the fork; and

(c) at least three electrodes connected to each thin film, a first electrode being connected to a first side of each piezoelectric thin film and second and third electrodes being connected to a second side of each thin film;

such that the application of an alternating voltage to the electrodes causes the fork to resonate.

2. The resonator of claim 1, wherein the tuning fork is made of fused quartz, silicon, CVD diamond, or Al₂ O₃.

3. The resonator of claim 1, wherein the piezoelectric film comprises piezoceramics such as PZT, PLZT.

4. The resonator of claim 1, wherein the piezoelectric film comprises solid solution ferroelectric oxides such as SBN, or PBN.

5. The resonator of claim 1, wherein the piezoelectric film is ZnO, AlN, or PVF₂.

6. A thin film micromechanical resonator, comprising:

(a) a non-piezoelectric tuning fork having two tines;

(b) a piezoelectric thin film disposed only on an upper surface of each tine of the fork; and

(c) at least three electrodes connected to each thin film, a first electrode being connected to a first side of each piezoelectric thin film and second and third electrodes being connected to a second side of each thin film;

such that the application of an alternating voltage to the electrodes causes the fork to resonate.

7. The resonator claim 6, wherein the tuning fork is made of fused quartz, silicon, CVD diamond, or Al₂ O₃.

8. The resonator of claim 6, wherein the piezoelectric film comprises piezoceramics such as PZT, PLZT.

9. The resonator of claim 6, wherein the piezoelectric film comprises solid solution ferroelectric oxides such as SBN, or PBN.

10. The resonator of claim 6, wherein the piezoelectric film is ZnO, AlN, or PVF₂.