GB2042256A - Piezoelectric device - Google Patents
Piezoelectric device Download PDFInfo
- Publication number
- GB2042256A GB2042256A GB7905786A GB7905786A GB2042256A GB 2042256 A GB2042256 A GB 2042256A GB 7905786 A GB7905786 A GB 7905786A GB 7905786 A GB7905786 A GB 7905786A GB 2042256 A GB2042256 A GB 2042256A
- Authority
- GB
- United Kingdom
- Prior art keywords
- piezoelectric
- inner electrode
- electrode
- layer
- electrodes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
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- 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
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- Push-Button Switches (AREA)
Abstract
A piezoelectric device has a flexible piezoelectric member (3), made for example of polarized PVF2, and at least one soft, resiliently rm electrode (2 or 4) e.g. of electrically conductive rubber, in contact with the piezoelectric member (3). The invention can be applied in the form of a flexible cable having concentric electrodes (2,4) with the piezoelectric layer (3) interposed between them, the inner electrode having a core (1) of metal strands, and the outer electrode having a covering (5) of woven metal strands. Such a cable can be placed on or under the road surface to detect the passage of road vehicles or can be used under floors or along fences to detect intruders. <IMAGE>
Description
SPECIFICATION
Piezoelectric device
This invention relates to a piezoelectric device and arose in the design of a piezoelectric cable for use on or beneath a road surface to detect the passage of vehicles.
The invention provides a piezoelectric device comprising a flexible piezoelectric member and two electrodes in contact with the piezoelectric member, at least one of the electrodes being relatively soft compared with the piezoelectric material.
The use of a soft resiliently deformable electrode can give two advantages. Firstly, it can allow the piezoelectric member to become squashed, bend or otherwise deform under pressure in a way which would not otherwise be possible. This can give an improved piezoelectric response. Secondly, it enables a good and reliable electrical contact to be made between the electrode and the piezoelectric member.
A preferred feature of the invention is for the said one of the electrodes to include material which has a lower modulus of elasticity than that of the piezoelectric member. This electrode material may itself be electrically conductive. It can for example be natural or synthetic rubber which is made electrically conductive by the addition of carbon particles. Alternatively it can be a body of non-conductive rubber, or other deformable material, supporting a flexible conductive layer. The term "electrode" when used in this specification is to be construed as including such a combination of conductive and nonconductive parts.
When the material of the said one of the electrodes includes rubber or a synthetic elastomeric material it preferably has a hardness of between 75 and 110 international rubber hardness degrees. Optionally this is between 85 and 90 degrees.
The electrodes are advantageously of similar soft material.
In one form of the invention the piezoelectric device is a flexible cable of constant cross-section.
The piezoelectric member surrounds an inner electrode and is surrounded by an outer electrode, both electrodes being made of natural or synthetic conductive rubber. In order to give improved strength and conductivity the inner electrode may include a central metal core and the outer electrode may include an outer metal layer. The central core and the outer layer may each be constituted by a plurality of individual metal strands; this allowing flexing of the cable.
Further features of the invention will appear from the following description and the accompanying drawings of a piezoelectric cable constructed in accordance with the invention. In the drawings:
Figure 1 is a cross-section of a piezoelectric cable constructed in accordance with the invention, the cross-section being through a plane perpendicular to the length of the cable; and
Figure 2 is a side elevation of a portion of the cable with parts removed to reveal the internal construction.
Referring to the drawings it will be seen that the illustrated device is in the form of an elongate structure and comprises an inner electrode formed by a central core 1 made from a bundle of copper strands surrounded by an extended layer 2 of soft electrically conductive rubber. This layer 2, which is vulcanised after being extruded, supports a strip of polarized PVF2 which is wound around the layer 1 to form a flexible layer 3 having piezoelectric properties. Surrounding the layer 3 is an outer electrode formed by a layer 4 which, like layer 2, is formed of extruding electrically conductive rubber and then vulcanising it. On the outside of the layer 4 is a flexible metal layer 5 formed by interwoven strands of copper wire.
The metal layer 5 is protected by an outer insulating jacket 6 of synthetic rubber.
In use, the cable may be laid on or beneath the surface of a road. The steel core 1 and the flexible woven steel layer 5 are then connected to an instrument which enables the potential between them to be observed, recorded or otherwise sensed. When a vehicle passes over the cable the layers 4, 5, and 6 are subject to pressure which is transferred to the piezoelectric layer 3. The pressure on this layer generates a potential difference between its opposite surfaces and, because layers 2 and 4 are conductive, this potential difference appears between the core 1 and the metal layer 5.
The invention is not applicable only to the detection of vehicles. It can be used in many other circumstances where it is desired to detect some form of deformation. For example it may be laid under floors or along fences to detect disturbances caused by intruders.
Because the layers 2 and 4 are made of rubber of other soft squashable material the piezoelectric material 3 can readily deform when pressure or other strain is applied to the cable. This gives an enhanced piezoelectric response. The soft squashable nature of the layers 2 and 4 also ensures that a good electrical contact is made between the piezoelectric layer 3 and the contiguous rubber surfaces of the layers 2 and 4.
Because the conductive rubber of the inner electrode 2 has a low modulus of bulk compressibility; when the cable is subjected to pressure, the electrode 2 squashes outwardly thus stretching the PVF2 layer and thereby increasing the piezoelectric response.
Claims (9)
1. A piezoelectric device comprising a flexible
piezoelectric member and two electrodes in contact with the piezoelectric member, at least one of the electrodes being relatively soft compared with the
piezoelectric material.
2. A device according to claim 1 in which the said one of the electrodes comprises material having a
lower modulus of elasticity than that of the piezoelectric member.
3. A device according to claim 2 in which the said electrode material is electrically conductive.
4. A device according to claim 3 in which the said electrode material contains natural or a synthetic rubber.
5. A device according to any preceding claim in which the piezoelectric member surrounds the said one of the electrodes.
6. A device according to any preceding claim in which the said one of the electrodes supports the piezoelectric member.
7. A device according to claim 6 and including an inner electrode; a piezoelectric member surrounding the inner electrode; and an outer electrode surrounding the piezoelectric member.
8. A device according to any preceding claim in which the outer electrode includes an outer metal layer.
8. A device according to claim 7 in which the inner electrode includes a central metal core.
9. A device according to claim 7 or 8 in which the outer electrode includes an outer metal layer.
10. A device according to any preceding claim including an outer insulating jacket.
11. A piezoelectric device substantially as described with reference to the accompanying drawings and substantially as illustrated therein.
New claims or amendments to claims filed on 14 Jay 1980 Superseded claims 1 to
9. Subsequent claims renumbered.
New or amended claims:
1. A piezoelectric device comprising an inner electrode, a piezoelectric layer surrounding the inner electrode, and an outer electrode surrounding the
piezoelectric layer, the materials of the device being
such that pressure applied to it resiliently squashes the inner electrode and deforms the piezoelectric
element thereby producing an electrical signal on the electrodes.
2. A device according to claim 1 in which the piezoelectric layer is a layer of polarised synthetic plastics material.
3. A device according to claim 1 or 2 in which the inner electrode comprises material having a lower modulus of elasticity than that of the piezoelectric layer.
4. A device according to claim 3 in which the said material of the inner electrode contains a natural or synthetic rubber.
5. A device according to any preceding claim in which the outer electrode comprises a natural or synthetic rubber.
6. A device according to any preceding claim in which the inner electrode supports the piezoelectric layer.
7. A device according to any preceding claim in which the inner electrode includes a central metal core.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7905786A GB2042256B (en) | 1979-02-19 | 1979-02-19 | Piezoelectric device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7905786A GB2042256B (en) | 1979-02-19 | 1979-02-19 | Piezoelectric device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2042256A true GB2042256A (en) | 1980-09-17 |
| GB2042256B GB2042256B (en) | 1983-08-17 |
Family
ID=10503282
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7905786A Expired GB2042256B (en) | 1979-02-19 | 1979-02-19 | Piezoelectric device |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2042256B (en) |
Cited By (31)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2519503A1 (en) * | 1981-12-31 | 1983-07-08 | Thomson Csf | POLYMER PIEZOELECTRIC TRANSDUCERS AND METHOD FOR MANUFACTURING THE SAME |
| GB2123602A (en) * | 1982-07-06 | 1984-02-01 | Raytheon Co | Piezoelectric transducer and method of making same |
| GB2138983A (en) * | 1983-03-25 | 1984-10-31 | Graham David Francis Sharp | Portable alarm system |
| US4568851A (en) * | 1984-09-11 | 1986-02-04 | Raychem Corporation | Piezoelectric coaxial cable having a helical inner conductor |
| US4609845A (en) * | 1984-07-06 | 1986-09-02 | Raychem Corporation | Stretched piezoelectric polymer coaxial cable |
| US4629925A (en) * | 1983-11-22 | 1986-12-16 | Raychem Corporation | Piezoelectric coaxial cable |
| US4688306A (en) * | 1984-07-06 | 1987-08-25 | Raychem Corporation | Method of preparing a piezoelectric device |
| FR2596568A1 (en) * | 1986-03-25 | 1987-10-02 | Thomson Csf | Piezoelectric cable and process for manufacturing a cable |
| GB2192460A (en) * | 1986-07-08 | 1988-01-13 | John Keith Millns | Movement sensing apparatus |
| GB2196740A (en) * | 1986-10-27 | 1988-05-05 | Ministry Of Agriculture Fisher | Device for assessing stress during processing |
| US4809244A (en) * | 1985-12-05 | 1989-02-28 | Focas Limited | Support member for pressure sensor |
| DE3833493A1 (en) * | 1988-10-01 | 1990-04-05 | Kabelmetal Electro Gmbh | Method for producing a piezoelectric lead |
| US5024872A (en) * | 1986-02-27 | 1991-06-18 | Raytheon Company | Sheets of stretched and polarized polymer materials and method of manufacturer |
| GB2266806A (en) * | 1992-05-06 | 1993-11-10 | Dowty Maritime Ltd | Piezoelectric device |
| US5363344A (en) * | 1987-08-10 | 1994-11-08 | Sofen Michael E | Acoustic sensor having a shell-mounted transducer |
| US5410210A (en) * | 1992-07-08 | 1995-04-25 | Kureha Kagaku Kogyo Kabushiki Kaisha | Piezoelectric device and process for production thereof |
| US5448232A (en) * | 1989-05-03 | 1995-09-05 | Mitron Systems Corporation | Roadway sensors and method of installing same |
| US5554907A (en) * | 1992-05-08 | 1996-09-10 | Mitron Systems Corporation | Vehicle speed measurement apparatus |
| US7732999B2 (en) | 2006-11-03 | 2010-06-08 | Danfoss A/S | Direct acting capacitive transducer |
| US7785905B2 (en) | 2001-12-21 | 2010-08-31 | Danfoss A/S | Dielectric actuator or sensor structure and method of making it |
| US7808163B2 (en) | 2000-11-02 | 2010-10-05 | Danfoss A/S | Multilayer composite and a method of making such |
| US7843111B2 (en) | 2000-11-02 | 2010-11-30 | Danfoss A/S | Dielectric composite and a method of manufacturing a dielectric composite |
| US7868221B2 (en) | 2003-02-24 | 2011-01-11 | Danfoss A/S | Electro active elastic compression bandage |
| US7880371B2 (en) * | 2006-11-03 | 2011-02-01 | Danfoss A/S | Dielectric composite and a method of manufacturing a dielectric composite |
| US7895728B2 (en) | 2002-09-20 | 2011-03-01 | Danfoss A/S | Method of making a rolled elastomer actiuator |
| US8181338B2 (en) | 2000-11-02 | 2012-05-22 | Danfoss A/S | Method of making a multilayer composite |
| GB2494530A (en) * | 2011-09-07 | 2013-03-13 | Pielleitalia S R L | Composite material comprising a layer of polymeric piezoelectric material matched with a textile substrate and method for making such a composite material |
| US8692442B2 (en) | 2012-02-14 | 2014-04-08 | Danfoss Polypower A/S | Polymer transducer and a connector for a transducer |
| US8891222B2 (en) | 2012-02-14 | 2014-11-18 | Danfoss A/S | Capacitive transducer and a method for manufacturing a transducer |
| US20170331027A1 (en) * | 2014-12-02 | 2017-11-16 | Industry-University Cooperation Foundation Hanyang University | Piezoelectric fiber having excellent flexibility and elasticity, and method for manufacturing the same |
| CN112368555A (en) * | 2018-10-29 | 2021-02-12 | 睿博传感技术研究株式会社 | Sensor wire and sensor circuit |
-
1979
- 1979-02-19 GB GB7905786A patent/GB2042256B/en not_active Expired
Cited By (41)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0086922A1 (en) * | 1981-12-31 | 1983-08-31 | Thomson-Csf | Method of production of piezo-electric polymer transducers |
| FR2519503A1 (en) * | 1981-12-31 | 1983-07-08 | Thomson Csf | POLYMER PIEZOELECTRIC TRANSDUCERS AND METHOD FOR MANUFACTURING THE SAME |
| US4670074A (en) * | 1981-12-31 | 1987-06-02 | Thomson-Csf | Piezoelectric polymer transducer and process of manufacturing the same |
| GB2123602A (en) * | 1982-07-06 | 1984-02-01 | Raytheon Co | Piezoelectric transducer and method of making same |
| GB2138983A (en) * | 1983-03-25 | 1984-10-31 | Graham David Francis Sharp | Portable alarm system |
| US4629925A (en) * | 1983-11-22 | 1986-12-16 | Raychem Corporation | Piezoelectric coaxial cable |
| US4715098A (en) * | 1983-11-22 | 1987-12-29 | Raychem Limited | Method of making coaxial cable |
| US4609845A (en) * | 1984-07-06 | 1986-09-02 | Raychem Corporation | Stretched piezoelectric polymer coaxial cable |
| US4688306A (en) * | 1984-07-06 | 1987-08-25 | Raychem Corporation | Method of preparing a piezoelectric device |
| EP0174837A2 (en) * | 1984-09-11 | 1986-03-19 | Focas Limited | Piezoelectric coaxial cable having a helical inner conductor |
| US4568851A (en) * | 1984-09-11 | 1986-02-04 | Raychem Corporation | Piezoelectric coaxial cable having a helical inner conductor |
| EP0174837A3 (en) * | 1984-09-11 | 1988-03-09 | Focas Limited | Piezoelectric coaxial cable having a helical inner conductor |
| US4809244A (en) * | 1985-12-05 | 1989-02-28 | Focas Limited | Support member for pressure sensor |
| US5024872A (en) * | 1986-02-27 | 1991-06-18 | Raytheon Company | Sheets of stretched and polarized polymer materials and method of manufacturer |
| FR2596568A1 (en) * | 1986-03-25 | 1987-10-02 | Thomson Csf | Piezoelectric cable and process for manufacturing a cable |
| GB2192460B (en) * | 1986-07-08 | 1990-08-01 | John Keith Millns | Respiratory movement sensing assemblies and apparatus |
| GB2192460A (en) * | 1986-07-08 | 1988-01-13 | John Keith Millns | Movement sensing apparatus |
| US4829812A (en) * | 1986-10-27 | 1989-05-16 | The Minister Of Agriculture, Fisheries And Food In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Device for assessing processing stresses |
| GB2196740B (en) * | 1986-10-27 | 1990-08-15 | Ministry Of Agriculture Fisher | Device for assessing processing stresses |
| GB2196740A (en) * | 1986-10-27 | 1988-05-05 | Ministry Of Agriculture Fisher | Device for assessing stress during processing |
| US5363344A (en) * | 1987-08-10 | 1994-11-08 | Sofen Michael E | Acoustic sensor having a shell-mounted transducer |
| DE3833493A1 (en) * | 1988-10-01 | 1990-04-05 | Kabelmetal Electro Gmbh | Method for producing a piezoelectric lead |
| US5448232A (en) * | 1989-05-03 | 1995-09-05 | Mitron Systems Corporation | Roadway sensors and method of installing same |
| GB2266806A (en) * | 1992-05-06 | 1993-11-10 | Dowty Maritime Ltd | Piezoelectric device |
| GB2266806B (en) * | 1992-05-06 | 1996-01-24 | Dowty Maritime Ltd | Piezoelectric device |
| US5554907A (en) * | 1992-05-08 | 1996-09-10 | Mitron Systems Corporation | Vehicle speed measurement apparatus |
| US5410210A (en) * | 1992-07-08 | 1995-04-25 | Kureha Kagaku Kogyo Kabushiki Kaisha | Piezoelectric device and process for production thereof |
| US8181338B2 (en) | 2000-11-02 | 2012-05-22 | Danfoss A/S | Method of making a multilayer composite |
| US7808163B2 (en) | 2000-11-02 | 2010-10-05 | Danfoss A/S | Multilayer composite and a method of making such |
| US7843111B2 (en) | 2000-11-02 | 2010-11-30 | Danfoss A/S | Dielectric composite and a method of manufacturing a dielectric composite |
| US7785905B2 (en) | 2001-12-21 | 2010-08-31 | Danfoss A/S | Dielectric actuator or sensor structure and method of making it |
| US7895728B2 (en) | 2002-09-20 | 2011-03-01 | Danfoss A/S | Method of making a rolled elastomer actiuator |
| US7868221B2 (en) | 2003-02-24 | 2011-01-11 | Danfoss A/S | Electro active elastic compression bandage |
| US7880371B2 (en) * | 2006-11-03 | 2011-02-01 | Danfoss A/S | Dielectric composite and a method of manufacturing a dielectric composite |
| US7732999B2 (en) | 2006-11-03 | 2010-06-08 | Danfoss A/S | Direct acting capacitive transducer |
| GB2494530A (en) * | 2011-09-07 | 2013-03-13 | Pielleitalia S R L | Composite material comprising a layer of polymeric piezoelectric material matched with a textile substrate and method for making such a composite material |
| US8692442B2 (en) | 2012-02-14 | 2014-04-08 | Danfoss Polypower A/S | Polymer transducer and a connector for a transducer |
| US8891222B2 (en) | 2012-02-14 | 2014-11-18 | Danfoss A/S | Capacitive transducer and a method for manufacturing a transducer |
| US20170331027A1 (en) * | 2014-12-02 | 2017-11-16 | Industry-University Cooperation Foundation Hanyang University | Piezoelectric fiber having excellent flexibility and elasticity, and method for manufacturing the same |
| US10756251B2 (en) * | 2014-12-02 | 2020-08-25 | Industry-University Cooperation Foundation Hanyang University | Piezoelectric fiber having excellent flexibility and elasticity, and method for manufacturing the same |
| CN112368555A (en) * | 2018-10-29 | 2021-02-12 | 睿博传感技术研究株式会社 | Sensor wire and sensor circuit |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2042256B (en) | 1983-08-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |