Measuring and testing – Specimen stress or strain – or testing by stress or strain... – Specified load or strain transmission device from specimen...
Reexamination Certificate
1999-02-19
2004-04-06
Patel, Harshad (Department: 2855)
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
Specified load or strain transmission device from specimen...
Reexamination Certificate
active
06715363
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a novel method and apparatus for strain amplification for piezoelectric transducers. Specifically, the invention relates to strain amplification by elevating the piezoelectric crystal above the neutral axis of the plate by castellations formed on the plate.
BACKGROUND OF THE INVENTION
The measurement of strain is accomplished using a piezoelectric crystal mounted on a supporting plate which is attached to a base which communicates with a structure to be monitored. In the typical case, the crystal is mounted on a so-called “unimorph” supporting plate which is attached in direct contact over substantially the entire surface of the piezoelectric crystal. It has long been well known to make such unimorph transducers using piezoelectric materials. It has also long been well known that single crystal piezoelectric materials could be used in such unimorph transducers. However, the sensitivity of such a transducer structure is limited by the physical dimensions and material properties of the sensing components of the transducer. It is therefore desirable to improve the sensitivity for a transducer of a given class or application without changing the overall physical dimensions of the transducer.
SUMMARY OF THE INVENTION
The present invention addresses the shortcomings of the existing piezoelectric transducers and provides improved sensitivity for a given application by providing a transducer configuration which amplifies the strain for a transducer otherwise having the same given physical dimensions and made up of the same given transducer materials. This is accomplished by a transducer having a mounting plate for mounting the piezoelectric crystal in which the mounting plate has raised protrusions which offset the crystal from the surface of the mounting plate. In profile, these protrusions resemble the gun placements of a castle turret and hence are referred to herein as “castellations.” The castellations produce significant increases in sensitivity. Circular or waffle pattern castellations are specifically shown, although other configurations are contemplated.
The devices which utilize the method and apparatus of the present invention (for example, accelerometers, velocity sensors, impedance heads, and hydrophones) exhibit a higher charge sensitivity and resonance frequency than existing transducers. These advantages extend the number of applications and efficacy of the devices. It is the purpose of this invention to provide a predictable and hitherto unattained quality factor as is defined herein. Moreover, the simplicity of the design and micromachined, photoetched castellated components contribute to a low cost of manufacturing not evidenced in the existing transducers. This is achieved by using the castellated surface on which the piezoelectric transducer is mounted.
REFERENCES:
patent: 3311761 (1967-03-01), Schloos
patent: 3697790 (1972-10-01), Flint et al.
patent: 3858440 (1975-01-01), Budraitis
patent: 3891870 (1975-06-01), Corbett
patent: 4189655 (1980-02-01), Bruel
patent: 4314481 (1982-02-01), Wolfer et al.
patent: 4439705 (1984-03-01), Corbett
patent: 4473768 (1984-09-01), Kerr et al.
patent: 5029478 (1991-07-01), Wamstad
patent: 5339697 (1994-08-01), Mullin
patent: 5604667 (1997-02-01), Morimoto
patent: 5638822 (1997-06-01), Seyed-Bolorforosh et al.
patent: 5767405 (1998-06-01), Bernstein et al.
patent: 5841217 (1998-11-01), Kizaki et al.
patent: 5889214 (1999-03-01), Kang et al.
patent: 5912601 (1999-06-01), Unami et al.
Brooks, III Thurston L.
Deng Kan
Schloss Fred
Wlodkowski Paul A.
Blank Rome LLP
Patel Harshad
Wilcoxon Research, Inc.
LandOfFree
Method and apparatus for strain amplification for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for strain amplification for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for strain amplification for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3186373