GB2144906A - Piezo-electric sensor and method of manufacture - Google Patents
Piezo-electric sensor and method of manufacture Download PDFInfo
- Publication number
- GB2144906A GB2144906A GB08416262A GB8416262A GB2144906A GB 2144906 A GB2144906 A GB 2144906A GB 08416262 A GB08416262 A GB 08416262A GB 8416262 A GB8416262 A GB 8416262A GB 2144906 A GB2144906 A GB 2144906A
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- Prior art keywords
- piezo
- electric
- sensor
- mould
- resin
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- 238000000034 method Methods 0.000 title claims abstract description 15
- 238000004519 manufacturing process Methods 0.000 title claims description 19
- 239000000843 powder Substances 0.000 claims abstract description 33
- 239000000463 material Substances 0.000 claims abstract description 25
- 239000000919 ceramic Substances 0.000 claims abstract description 20
- 239000011810 insulating material Substances 0.000 claims abstract description 7
- 229920003002 synthetic resin Polymers 0.000 claims abstract description 6
- 239000000057 synthetic resin Substances 0.000 claims abstract description 6
- 238000000465 moulding Methods 0.000 claims abstract description 4
- 239000002305 electric material Substances 0.000 claims description 42
- 229920005989 resin Polymers 0.000 claims description 27
- 239000011347 resin Substances 0.000 claims description 27
- 238000001723 curing Methods 0.000 claims description 14
- 230000005684 electric field Effects 0.000 claims description 13
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 7
- 229910052802 copper Inorganic materials 0.000 claims description 7
- 239000010949 copper Substances 0.000 claims description 7
- 238000007711 solidification Methods 0.000 claims description 7
- 230000008023 solidification Effects 0.000 claims description 7
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 6
- 238000002347 injection Methods 0.000 claims description 4
- 239000007924 injection Substances 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 229920005992 thermoplastic resin Polymers 0.000 claims description 4
- 239000004411 aluminium Substances 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 150000002118 epoxides Chemical class 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 239000002184 metal Substances 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 238000002844 melting Methods 0.000 claims description 2
- 230000008018 melting Effects 0.000 claims description 2
- 239000004417 polycarbonate Substances 0.000 claims description 2
- 229920000515 polycarbonate Polymers 0.000 claims description 2
- 238000001029 thermal curing Methods 0.000 claims description 2
- JPJZHBHNQJPGSG-UHFFFAOYSA-N titanium;zirconium;tetrahydrate Chemical group O.O.O.O.[Ti].[Zr] JPJZHBHNQJPGSG-UHFFFAOYSA-N 0.000 claims description 2
- 229920001187 thermosetting polymer Polymers 0.000 claims 1
- 230000010287 polarization Effects 0.000 description 9
- 230000035945 sensitivity Effects 0.000 description 7
- 238000001514 detection method Methods 0.000 description 5
- 239000012530 fluid Substances 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 239000004033 plastic Substances 0.000 description 4
- 230000035939 shock Effects 0.000 description 4
- 238000011049 filling Methods 0.000 description 3
- 230000028161 membrane depolarization Effects 0.000 description 3
- 230000001174 ascending effect Effects 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 230000002441 reversible effect Effects 0.000 description 2
- 238000007669 thermal treatment Methods 0.000 description 2
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical group [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003467 diminishing effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- -1 for example Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/60—Piezoelectric or electrostrictive devices having a coaxial cable structure
Landscapes
- Measuring Fluid Pressure (AREA)
- Testing Or Calibration Of Command Recording Devices (AREA)
Abstract
A piezo-electric sensor comprises two metallic electrodes insulated electrically from each other by a material including a piezo-electric ceramic powder, and means for connecting the electrodes to a voltage-measuring device. Such sensors may be used, for example, for detecting vibrations, variations in pressure, and the position of an article. The material consists of a synthetic resin in which the piezo- electric ceramic powder is dispersed, which powder is electrically polarised in one principal direction. Such a piezo-electric sensor is manufactured by a method in which the final shape of the material including the piezo-electric ceramic powder is obtained by moulding. The electrodes constitute a part of the mould; the other mould parts comprise insulating material which can be removed after curing. The sensor may be of flat or cylindrical form.
Description
SPECIFICATION
Piezo-electric sensor and method of manufacturing such a sensor
The invention relates to a piezo-electric sensor comprising two metallic electrodes insulated electrically from each other by a material including a piezo-electric ceramic powder, and comprising means to connect said electrodes to a device for measuring electric voltages.
Sensors manufactured according to the invention find their application in the detection of vibrations and variations in pressure in a temperature range between - 80"C and + 120 C.
It is known to manufacture piezo-electric sensors of the "VIBRACOAX" (Trade Mark) type manufactured by Thermocoax et Cie and constituted by a cylindrical envelope of copper and an axial electrode also of copper insulated from each other by a piezo-electric ceramic powder. Any elastic or plastic deformation of the outer envelope results in stresses on the piezo-electric powder and the generation of electric charges and hence in the appearance of a potential difference between the envelope and the axial electrode.
However, the sensitivity of such a sensor diminishes irreversibly when it is subjected to temperatures higher than 100'C due to the depolarization of the piezo-electric grains.
It is also known to manufacture sensors comprising other piezo-electric materials, for example sintered ceramics or, for example, sheets of polymers charged with piezo-electric powder of the type described in Japanese
Patent Specification No. 66912 D/37.
These products, however, have a solid shape and the adaptation to an application other than that for which they are destined originally questions their whole conception.
For example, each new manufacture of a solid piezo-electric ceramic sensor destined for a new usage supposes the use of means not only for the manufacture of the metallic electrodes of the sensor but also for the ceramic, which will increase the manufacturing cost.
Moreover, experience proves that the use of polymeric sheets charged with piezo-electric powder such as described in the said Japanese Patent Specification No. 66912 D/37 only yields a disappointing result due to the fact that the stresses produced in the piezoelectric material are entirely absorbed by the synthetic support which is too plastic and are not transmitted to the incorporated piezo-electric powder. Finally, even if a solution were found to improve the results given by such sheets, the latter would be of a restricted use only and not adaptable to any form of sensor.
It is the object of the invention to mitigate said disadvantages and to propose a piezoelectric sensor such as described in the opening paragraph, which is characterized in that said material is composed of a synthetic resin in which the piezo-electric ceramic powder is dispersed and is electrically polarized according to one principal direction.
The present invention includes the following preferred embodiments of the piezo-electric sensor:
the piezo-electric powder is a titanium zirzonate of lead sintered at a high temperature;
the piezo-electric material is composed of 10% of resin and 90% of piezo-electric powder;
the electrodes are manufactured from a metal selected among copper,nickel or aluminium;
the resin is a thermocurable resin, particularly an epoxide;
the resin is a thermoplastic resin particularly plycarbonate.
The invention also relates to a method of manufacturing the above given piezo-electric sensor, which method is characterized in that the final shape of the solid piezo-electric material is obtained by moulding;
A preferred embodiment by which a sensor is obtained of which the piezo-electric material includes a thermocurable resin, is characterized in that the piezo-electric material is introduced into a mould at ambient temperature, and that the assembly thus formed is heated at a suitable temperature to produce the curing of the resin while remaining below the
Curie-temperature of the piezo-electric powder, while at the same time an electric field is applied so as to polarize the piezo-electric material linearly.
Another preferred embodiment by which a sensor is obtained, the piezo-electric material of which includes a thermoplastic resin, is characterized in that the piezo-electric material is introduced into a mould by injection at a temperature suitable to produce the melting of the resin while remaining below the Curietemperature of the piezo-electric powder, while at the same time an electric field is applied so as to polarize the piezo-electric material linearly and in that the assembly is then cooled to produce the solidification of the resin.
In a further preferred embodiment the method of the invention is characterized in that the first electrode constitutes at least a part of the mould destined to receive the piezo-electric material when the latter is in the viscous state, in that the other parts, if any, of said mould are manufactured from an insulating material, which other parts may optionally be removed after curing or solidification of the piezo-electric material, and in that the second electrode is immersed in the piezo-electric material prior to curing or solidification of said material, whereby a part of said second electrode remains accessible to the connection means of the device for measuring the electric voltage.
In another favourable embodiment of the method according to the invention the two electrodes constitute a part of the mould destined to receive the piezo-electric material when the latter is in the viscous state, the other parts of said mould being manufactured by means of supplementary parts from an insulating material which may be removed optionally after curing or solidification of the piezo-electric material.
Further special embodiments of the said method are the following:
A manufacturing method in which the first electrode constitutes the walls of a mould in the form of a rectangular parallelepiped of which the upper face is omitted so as to permit the introduction of the piezo-electric material and of the second flat electrode parallel to two of the lateral faces of said rectangular parallelepiped.
This method is used for the manufacture of a flat sensor.
A manufacturing method in which the first electrode constitutes the laterial walls of a cylindrical mould of which one of the bases is formed by an insulating plate and the second base of which is omitted so as to permit the introduction of the piezoelectric material and of the second likewise cylindrical electrode parallel to the axis of the mould.
The latter method is used for the manufacture of a cylindrical sensor the second electrode of which is a rod or a tube.
A manufacturing method is which the two electrodes constitute two parallel walls of a mould in the form of a rectangular parallelepiped.
In the manufacture of the sensors according to the invention any form adapted to the very different applications is possible without machining other than that of metallic pieces of electrodes, which reduces the cost of manufacture. On the other hand, the sensitivity of such sensors is improved in the range of temperatures above 80 C. In particular, the diminishing of the sensitivity of the sensor above 80 C is totally reversible.
From the following description with reference to the accompanying drawings it will be better understood how the invention is realized.
Figures la and 1b are a longitudinal sectional view and an underneath view, respectively, of a flat sensor manufactured according to the invention,
Figures 2a and 2b are a longitudinal sectional view and an underneath view, respectively, of a flat sensor according to a second embodiment of the Invention
Figures 3a and 3b are a longitudinal sectional view and an underneath view, respectively. of a flat sensor according to a third embodiment of the invention.
Figures 4a and 4b are a longitudinal sectional view and a cross-sectional view, respectively, of a cylindrical sensor according to the invention.
Figure 5 shows such a cylindrical sensor which can be adapted around a system of pipes.
Figure 6 shows the directions of polarization of the grains of the piezo-electric powder in a material according to the invention before the thermal treatment in a direct current electric field, and Figure 6a shows the directions of polarization of the same piezo-electric powder after said treatment.
Figure 7 shows the signal response of the flat sensor according to the invention relative to a constant shock as a function of the temperature for a given piezo-electric material
As shown in Figs. 1 and 2, the flat sensor described by way of non-limiting example comprises a first electrode 1 which may be of copper and which serves as a mould for the piezo-electric material 2. The second electrode 3 is embedded in the material 2 and is hence insulated from the first electrode 1.
In order to ensure the function of the mould for the piezo-electric material, the first electrode of the flat sensor may have various shapes. In the sensor shown in Fig. 1 the first electrode 1 is in the form of a rectangular parallelepiped without upper face. The upper face serves for the filling with pieze-electric material 2 and for the introduction of the second electrode 3. The latter has dimensions which are suitable in order that the space left between the two electrodes and filled with electrically insulating piezo-electric material is sufficiently large to avoid electric breakdown between them. An ascending portion 4 of the piezo-electric material for moulding the electrode 3 is also favourable to avoid breakdowns since said ascending portion enlarges the distance in the air between the two electrodes.In the sensor shown in Fig. 2 the first electrode 1 has the form of a rectangular parallelepiped without upper face and without small lateral faces. The small lateral faces are realized by gluing or screwing side plates 5 of an insulating material, for example, plastic or teflon, which may or may not be removed after curing of the resin. The piezo-electric material 2 insulates the electrodes 1 and 3 from each other. The side plates 5 being electrically insulating, the electrode 3 may have the same length as the electrode 1.
The flat sensor shown in Fig. 3 also has the form of a rectangular parallelepiped. The electrodes 1 and 3 are placed according to each of the large lateral faces of the rectangular parallelepiped. Side plates of insulating material are glued or screwed to the lower face 6 and the small lateral faces 5 so as to ensure the tightness during operation of the mould.
Said side plates could also be removed after curings of the resin, if so desired.
In all the flat sensors of any of the types shown in Figs. 1 to 3 the dimensions and the materials constituting the sensor are adapted to the phenomenon to be detected.
The field of application may be that of passage detectors. In this case the sensor is buried and placed in the passage of pedestrians, vehicles or airplanes. The sensor may be used for the detection of introducers, to count vehicles at the entry or exit of gates.
Such a sensor has certain advantages over the conventional sensors applied for the above-mentioned uses (pneumatic tyres, mechanical pedals). The sensors according to the invention may in fact be made invisible and non-detectable for they are passive sensors manufactured from a non-magnetic material.
Moreover, their constitution predicts an impotant life expectancy as compared with conventional sensors.
The field of application of the flat sensors also comprises the detection of position. The sensor, placed in suitable surroundings between two moving parts transmits a signal when the two parts come in contact. So it may be applied to the detection of closing doors (SNCF or RATP carriages) to the detection of closing moulds for injection or stamping. The emitted signal may also indicate the closing pressure.
In the cylindrical type of sensor shown in
Fig. 4 the two electrodes 1 and 3 are cylindrical, hollow and coaxial. One of the bases of the cylinder is obturated during the filling with piezo-electric material 2 by insulating side plate 5. The other base of the cylinder is or is not obturated after the filling by a second insulating side plate 5 to ensure the tightness of the assembly during the curing operation of the resin, according to the position which the sensor must take with respect to the direct current electric field to which it is then submitted. Said plates 5 may be removed after the curing of the resin.
The cylindrical sensors as shown in Fig. 4 operate essentially as pressure variation sensors. The central electrode 3 is made hollow in order to receive the fluid the pressure of which is to be measured. Said electrode 3 is connected to the system of pipes in which said fluid circulates by means of two standardized connections fixed to each of its extremities, or by any other suitable means. Any variation in the fluid pressure is transmitted to the piezo-electric material and hence creates a signal which is connected between the central electrode 3 (which may, for example, be connected to mass electrically) and the peripheral electrode.
The dimensions and the natures of the materials of said cylindrical sensors are chosen in accordance with the pressures and fluids to be studied. In particular the electrodes may be manufactured from any electrically conductive material which is compatible with the interior fluid.
In the case where it is not possible to connect the sensor directly to the tubing, this latter may be done in two parys destined to be connected to said tubing.Fig. 5 is a crosssectional view of such a sensor which is open at 12 and connected to a tubing 11.
The field of application of the cylindrical sensors manufactured according to the invention extends to the measurement of the variations in pressure at the output of injection pumps for explosion motors or internal combustion engines, to the measurements of the speed of rotation and control of the rotation of the pump. Said field also extends to the measurements of the variation in pressure on hydrualic or pneumatic servo systems comprising the control of the gripping or positioning movements of robots. Finally it extends to the direction of vibrations of piping systems.
Fig. 6a shows the microstructure of the piezo-electric powder before the thermal treatment in a direct current electric field. From an electrical point of view the piezo-electric ceramic which permits of obtaining the powder by grinding may be considered to be composed of elementry dipoles. Said elementary dipoles consist of two charges, one positive, the other negative, separated by a small distance as shown in Fig. 6a. Each ceramic grain may contain several of said dipoles. During the manufacture of the ceramic, said dipoles show no preference whatsoever to a particular direction in such manner that they are oriented in an arbitrary manner in each powder grain, in the powder itself and in the mixture powderresin.If a stress is applied to the material thus manufactured, the sum of the displacements of the charges is none in such manner that in said conditions there is no piezo-electric effect whatsoever.
In order to obtain a piezo-electric effect in the matrial the dipoles must first be oriented, which is realized by subjecting the piezoelectric material to a strong external direct current electric field at a temperature which is so high that the resin can withstand it, which temperature, however, is lower than the Curiepoint of the ceramic. At said temperature the spontaneously formed dipoles disappear and new dipoles are formed which are oriented parallel to the direction of the electric field H as shown in Fig. 6b, simultaneously with an elongation of the ceramic appearing in the same direction. In reality, the dipoles never have the ideal orientation suggested in Fig.
6b, for the structure of the ceramic permits only certain rotations of the dipoles and the temperature used in the case of the synthetic resin support remains remote from the Curietemperature of the ceramic.
When the action of the external electric field ceases and the material is cooled, the dipoles cannot easily return to their original position and a remanent polarization of the ceramic is obtained. This latter presents a permanent piezo-electric effect and may convert the me
chanical energy into electrical energy and conversely in such manner that, for example, the
electrical enegy which is produced and is
available between the electrodes is proportional to the applied pressure.
However, the electrical energy produced by a piezo-electric material depends on the one
hand on the electric field to which it has been subjected to obtain the remanent polarization, and on the other hand on the temperature to which it has been subjected during operation, and finally on the eleasticity of the material.
In said conditions it is ncessary, before using the sensors described above, to produce a standardization. For this purpose, the sensor is subjected to the shocks of a Charpy test and the charges induced for each shock of known
intensity are noted to constitute a standard curve which at the same time defines the range of efficacity of the sensor.
According to a preferred embodiment of the piezo-electric material, the latter is constituted by a ceramic powder of titanium zirconate of lead the Curie-point of which is of the order of 285 C and is either of a thermocurable resin of the epoxide type or of a thermofusible resin of the polycarbonate type.
When the resin is of the thermocuring type, before introduction of the piezo-electric material in the mould at ambient temperature, the assembly thus constituted is brought, at the same time it is subjected to a polarization treatment, to a temperature between 100 and 250 C, sufficient to obtain the curing of the resin and lower than the Curie-point of the piezo-electric powder. On the other hand it is subjected to an electric field of a value higher than 1 kV/mm and lower than the electric discharge field. Generally, the temperature and the electric field used to obtain the polarization are chosen as a function of the shape, the dimensions of the sensor and the piezoelectric material.
When the resin is of the thermofusible type, the piezo-electric material is on the contrary injected warm in the mould at a temperature also between 200 and 250 C, the polarization treatment being also carried out at said temprature. After this, the piezo-electric sensor thus formed is cooled to ambient temperature, during which cooling the curing of the resin is effected.
The piezo-electric properties deteriorate and the sensitivity of a sensor diminishes if said latter is subjected to temperatures approaching the temperature at which it has been subjected to obtain the remanent polarization.
In the case of sensors manufactured according to the invention said depolarization is perfectly reversible and the sensor reobtains the original sensitivity when the temperature diminishes. For a flat sensor manufactured according to the invention the response curve, as a function of the temperature, to a constant shock of 32 g given in a Charpy test is represented in Fig. 7. Said curve given by way of example is varied only in the case where the sensor is manufactured with readily defined materials (copper electrodes, piezoelectric material including the above-mentioned powder and the epoxide resin). For other materials the shape of the curve would be different. The sensitivity of such a sensor begins to diminish at temperatures above 60 .
However, the sensor remains efficacious up to approximately 120 C.
The preferred proportions to obtain the piezo-electric material are 10% of resin for 90% of piezo-electric powder. In fact with such proportions the depolarization of the powder is avoided without the plastic properties of the resin impeding the transmission of the deformations.
However, the effects of the imposed polarization diminish slightly with time. It may be considered that for sensor manufactured with the above-mentioned powder the sensitivity losses are of the order of 10% after 105 days (approximately 300 years) in normal use.
These results, added to the fact that the electrodes of the sensors may be manufactured from metals such as copper, nickel or aluminium, promise a great solidity and a long life for said sensors, making their application useful for the measurements to be effected in places which are difficult of access.
Finally it will be obvious that the application of the invention in the fields indicated above is not limitative and that numerous modified embodiments are possible without departing from the scope of this invention as defined hereinafter in the Claims.
Claims (15)
1. A piezo-electric sensor comprising two metallic electrodes insulated electrically from each other by a material including a piezoelectric ceramic powder, and comprising means to connect said electrodes to a device for measuring electric voltages, charaterized in that said material is composed of a synthetic resin in which the piezo-electric ceramic powder is dispersed and is electrically polarized according to one principal direction.
2. A piezo-electric sensor as claimed in
Claim 1, characterized in that the piezo-electric powder is a titanium zirconate of lead sintered at high temperature.
3. A sensor as claimed in any of the
Claims 1 or 2, characterized in that the piezoelectric material is composed of 10% of resin and 90% of piezo-electric powder.
4. A sensor as claimed in any of the
Claims 1 to 3, characterized in that the electrodes are manufactured from a metal selected among copper, nickel or aluminium.
5. A piezo-electric sensor as claimed in any of the Claims 1 to 4, characterized in that the synthetic resin is a thermocuring resin of the epoxide type.
6. A piezo-electric sensor as claimed in any of the Claims 1-4, characterized in that the synthetic resin is a thermoplastic resin of the polycarbonate type.
7. A method of manufacturing a piezoelectric sensor as claimed in any of the Claims 1-6, characterized in that the final shape of the solid piezo-electric material is obtained by moulding.
8. A method as claimed in Claim 7 for the manufacture of a sensor of which the piezoelectric material includes a thermocurable (thermosetting) resin characterized in that the piezo-electric material is introduced into a mould at ambient temperature, and that the asembly thus constituted is brought at a suitable temperature to produce the curing of the resin while remaining below the Curie-temperature of the piezo-electric powder, while simultneously an electric field is applied in such manner as to polarize the piezo-electric material linearly.
9. A method as claimed in Claim 7, for the manufacture of a sensor of which the piezo-electric material includes a thermoplastic resin characterized in that the piezo-electric material is introduced into a mould by injection at a temperature suitable to produce the melting of the resin while remaining below the Curie-temperature of the piezo-electric powder, while at the same time an electric field is applied in such a manner as to polarize the piezo-electric material linearly and in that said assembly is then cooled to produce the solidification of the resin.
10. A method as claimed in Claim 8 or 9, characterized in that the first electrode constitutes at least a part of the mould destined to receive the piezo-electric material when the latter is in the viscous state, in that the optional other parts of said mould are manufactured from an insulating material, which parts may be removed optionally after curing or solidification of the piezo-electric material, and in that the second electrode is immersed in the piezo-electric material before curings or solidification of the material whereby the electrode is accessible to the connection means of the device for measuring the electric voltage.
11. A method as claimed in Claim 8 or 9, characterized in that each of the two electrodes constitutes a part of the mould destined to receive the piezo-electric material when the latter is in the viscous state, the other parts of said mould being manufactured from an insulating material which can be removed optionally after curings or silidification of the piezo-electric material.
12. A method as claimed in Claim 10, characterized in that the first electrode constitutes the walls of a mould in the form of a rectangular parallelepiped the upper face of which is omitted so as to permit the introduction of the piezo-electric material and of the second flat electrode which is parallel to two of the lateral faces of said parallelepiped.
13. A method as claimed in Claim 10, characterized in that the first electrode constitutes the lateral walls of a cylindrical mould of which one of the bases is formed by an insulting plate and the second base of which is omitted so as to permit the introduction of the piezo-electric material and of the second electrode which is also cylindrical and parallel to the axis of the mould.
14. A method as claimed in Claim 11, characterized in that the two electrodes constitute two parallel walls of a mould in the form of a rectangular parallelepiped.
15. A piezo-electric sensor, substantially as herein described with reference to Figs. 1a and 1 b, or Figs. 2a and 2b, or Figs. 3a and 3b, or Figs. 4a and 4b, or Fig. 5 of the drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8311008A FR2548457A1 (en) | 1983-07-01 | 1983-07-01 | PIEZOELECTRIC SENSOR |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8416262D0 GB8416262D0 (en) | 1984-08-01 |
| GB2144906A true GB2144906A (en) | 1985-03-13 |
Family
ID=9290424
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08416262A Withdrawn GB2144906A (en) | 1983-07-01 | 1984-06-26 | Piezo-electric sensor and method of manufacture |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE3423321A1 (en) |
| FR (1) | FR2548457A1 (en) |
| GB (1) | GB2144906A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3819947A1 (en) * | 1987-09-08 | 1989-03-23 | Katsumi Tanino | PIEZOELECTRIC PRESSURE SENSITIVE ELEMENT AND METHOD FOR THE PRODUCTION THEREOF |
| GB2243946A (en) * | 1990-05-09 | 1991-11-13 | Plessey Res Caswell | A method of poling an electroactive composite material |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7304566B2 (en) * | 2003-11-19 | 2007-12-04 | Honda Motor Co., Ltd. | Collision detection sensor for vehicle and collision detection device for vehicle |
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| GB1090906A (en) * | 1963-10-24 | 1967-11-15 | Charles Ferencz Pulvari | Improvements in or relating to dielectric materials |
| GB1466704A (en) * | 1973-03-29 | 1977-03-09 | Siemens Ag | Production of piezoelectric bodies |
| GB1527639A (en) * | 1975-12-29 | 1978-10-04 | Mitsubishi Petrochemical Co | Piezo-electric materials |
| GB2033147A (en) * | 1978-09-21 | 1980-05-14 | Tokyo Shibaura Electric Co | Method for production of composite piezoelectric material |
| GB2068355A (en) * | 1979-12-26 | 1981-08-12 | Okazaki K | Method of manufacturing interconnected porous ceramics |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3820208A (en) * | 1971-09-29 | 1974-06-28 | Philips Corp | Method of manufacturing a piezoelectric element |
| GB2012519A (en) * | 1978-01-17 | 1979-07-25 | Atomic Energy Authority Uk | Piezoelectric devices |
| FR2501916A1 (en) * | 1981-03-13 | 1982-09-17 | Commissariat Energie Atomique | PIEZOELECTRIC COMPOSITE MATERIAL AND METHOD FOR MANUFACTURING THE SAME |
| FR2519503B1 (en) * | 1981-12-31 | 1991-09-06 | Thomson Csf | POLYMERIC PIEZOELECTRIC TRANSDUCERS AND MANUFACTURING METHOD |
-
1983
- 1983-07-01 FR FR8311008A patent/FR2548457A1/en active Pending
-
1984
- 1984-06-23 DE DE19843423321 patent/DE3423321A1/en not_active Withdrawn
- 1984-06-26 GB GB08416262A patent/GB2144906A/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB738265A (en) * | 1951-09-14 | 1955-10-12 | Standard Telephones Cables Ltd | Improvements in or relating to printed or otherwise deposited circuits |
| GB817935A (en) * | 1955-08-01 | 1959-08-06 | Renault | Improvements in or relating to a process for the manufacture of low tension sparkingplugs |
| GB1090906A (en) * | 1963-10-24 | 1967-11-15 | Charles Ferencz Pulvari | Improvements in or relating to dielectric materials |
| GB1466704A (en) * | 1973-03-29 | 1977-03-09 | Siemens Ag | Production of piezoelectric bodies |
| GB1527639A (en) * | 1975-12-29 | 1978-10-04 | Mitsubishi Petrochemical Co | Piezo-electric materials |
| GB2033147A (en) * | 1978-09-21 | 1980-05-14 | Tokyo Shibaura Electric Co | Method for production of composite piezoelectric material |
| GB2068355A (en) * | 1979-12-26 | 1981-08-12 | Okazaki K | Method of manufacturing interconnected porous ceramics |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3819947A1 (en) * | 1987-09-08 | 1989-03-23 | Katsumi Tanino | PIEZOELECTRIC PRESSURE SENSITIVE ELEMENT AND METHOD FOR THE PRODUCTION THEREOF |
| GB2243946A (en) * | 1990-05-09 | 1991-11-13 | Plessey Res Caswell | A method of poling an electroactive composite material |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3423321A1 (en) | 1985-01-31 |
| FR2548457A1 (en) | 1985-01-04 |
| GB8416262D0 (en) | 1984-08-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |