Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Patent
1995-07-31
1997-12-30
Dougherty, Thomas M.
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
310328, 310330, 310331, H01L 4108
Patent
active
057034257
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for manufacturing a piezoelectric component and to the component resulting from such a process.
Piezoelectric components are used, inter alia, in the field of acoustics. They then form part of the equipment of loudspeakers, microphones or even hydrophones.
The application described in the present patent application relates more particularly to acoustic sensors used for underwater detection and, especially, the sensors used in towed linear antennas.
However, the invention relates to all fields of application using piezoelectric components.
The acoustic sensors used in towed linear antennas generally consist of a piezoelectric dielectric piece to which are adhesively bonded two metallic electrodes.
The potential difference appearing at the terminals of the two electrodes is then a function of the difference in the pressures which are exerted on them.
In order to make the sensor insensitive to acceleration, it is known to one skilled in the art that the sensor consists of two piezoelectric dielectric pieces, the polarization directions of which are opposed.
The sensor thus formed is then mounted in a case so as to protect the piezoelectric pieces from chemicals, for example oil, which surround the component in the final mounting.
The manufacture of such a sensor has many drawbacks. Machining the piezoelectric pieces is difficult. The reason for this is that the dielectrics used are brittle and many pieces can break during handling operations.
Moreover, the piezoelectric pieces and the metallic electrodes are joined together by adhesive bonding, stacking the mechanical pieces flat, one on top of another, something which constitutes a lengthy and tedious operation.
Finally, the placing in a case requires an additional operation. This manufacturing process therefore requires tricky and quite lengthy operations leading to a high cost.
The invention does not have these drawbacks.
It is also known to manufacture piezoelectric components by rolling, such as those described in European Patent EP-A-0,190,574.
The subject of the invention is a process for manufacturing a piezoelectric component consisting of the stacking of at least one piezoelectric dielectric element and of at least two metallic electrodes, each piezoelectric element being inserted between two metallic electrodes, characterized in that each piezoelectric element and each metallic electrode is produced, respectively, by coiling a piezoelectric film and by coiling a metallized film.
The subject of the invention is also the piezoelectric component resulting from such a process.
One advantage of the invention is therefore the simplification of the process for manufacturing the piezoelectric components.
Other features and advantages of the invention will appear on reading a preferred embodiment, given with reference to the hereto-appended figures in which:
FIG. 1 represents a sectional view of a piezoelectric component according to the invention;
FIG. 2 represents a diagrammatic view of a machine allowing manufacture of piezoelectric components according to the preferred embodiment of the invention.
FIG. 1 is a sectional view of a piezoelectric component according to the invention.
This component is of the stacked type, but the invention also relates to components of the coiled type. For reasons of convenience, the component shown in FIG. 1 consists only of 2 piezoelectric elements 1 hugging a metallic electrode 2, the said piezoelectric elements 1 themselves being sandwiched between two metallic electrodes.
In general, the piezoelectric elements are n in number (n being an integer greater than or equal to 1) and are sandwiched in a regular manner Between n+1 metallized electrodes 2. According to the preferred embodiment of the invention, n =10. As shown in FIG. 1, two successive electrodes 2 surround one dielectric element and each of the two electrodes 2 exhibits an overhang d with respect to the dielectric element, the overhang exhibited by one being in the opposite direction to the overhang exhibited by the o
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Feral Thierry
Fromont Bernard
Lacour Olivier
Sernit Eric
Stephan Ronan
"Thomson-CSF"
Dougherty Thomas M.
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