GB1593272A - Electro-acoustic transducers - Google Patents
Electro-acoustic transducers Download PDFInfo
- Publication number
- GB1593272A GB1593272A GB235680A GB235680A GB1593272A GB 1593272 A GB1593272 A GB 1593272A GB 235680 A GB235680 A GB 235680A GB 235680 A GB235680 A GB 235680A GB 1593272 A GB1593272 A GB 1593272A
- Authority
- GB
- United Kingdom
- Prior art keywords
- transducer
- foils
- electrodes
- piezo
- electro
- 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.)
- Expired
Links
- 239000011888 foil Substances 0.000 claims description 22
- 239000000463 material Substances 0.000 claims description 10
- 239000004033 plastic Substances 0.000 claims description 10
- 229920003023 plastic Polymers 0.000 claims description 10
- 239000002033 PVDF binder Substances 0.000 claims description 5
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 5
- 239000004743 Polypropylene Substances 0.000 claims description 4
- 239000000853 adhesive Substances 0.000 claims description 4
- 230000001070 adhesive effect Effects 0.000 claims description 4
- 239000004794 expanded polystyrene Substances 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 4
- -1 polypropylene Polymers 0.000 claims description 4
- 229920001155 polypropylene Polymers 0.000 claims description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 229920009405 Polyvinylidenefluoride (PVDF) Film Polymers 0.000 claims description 2
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- 239000002131 composite material Substances 0.000 claims description 2
- 238000012423 maintenance Methods 0.000 claims description 2
- 238000000034 method Methods 0.000 claims description 2
- 229920000642 polymer Polymers 0.000 claims description 2
- 230000008439 repair process Effects 0.000 claims description 2
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R17/00—Piezoelectric transducers; Electrostrictive transducers
- H04R17/005—Piezoelectric transducers; Electrostrictive transducers using a piezoelectric polymer
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2499/00—Aspects covered by H04R or H04S not otherwise provided for in their subgroups
- H04R2499/10—General applications
- H04R2499/11—Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Reciprocating Pumps (AREA)
Description
(54) IMPROVEMENTS IN OR RELATING TO
ELECTRO-ACOUSTIC TRANSDUCERS
(71) We, STANDARD TELE
PHONES AND CABLES LIMITED, a
British Company, of 190 Strand, London
WC2R 1DU, England, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
This invention relates to electro-acoustic transducers, and particularly to a transducer employing a piezo-electric polymer diaphram as the active element.
A telephone subscriber's instrument usually employs a carbon microphone transmitter and a rocking armature electromagnetic receiver. Whilst such a combination is satisfactory in operation the necessity of manufacturing two different types of transducer results in relatively high production costs. Furthermore both types of transducer must be made available for repairs and maintenance of the telephone equipment.
Piezo-electric plastics film has recently become available, and this film can be electrically polarised and provided with surface electrodes such that a change in the linear dimensions of the film induces a potential difference between the electrodes and vice versa. In particular, electrically polarised polyvinylidene fluoride (PVDF) film shows this property.
According to the invention there is provided an electro-acoustic transducer which includes a diaphragm assembly formed by a sandwich assembly of a sheet of a passive plastics material having on each of its faces a foil of a piezo-electric plastics material, in which each said foil has surface electrodes and is electrically polarised so that movement of the diaphragm assembly generates potential differences between the electrodes of each of the foils, and vice versa, and in which the electrodes on said foils are coupled so that the two foils operate in pushpull.
An embodiment of the invention will now be described with reference to the drawing accompanying the Provisional Specification, which is a cross-section of a transducer fitted with a composite diaphragm.
The drawing shows a transducer fitted with a sandwich type diaphragm. The planar diaphram assembly 81 is mounted in a housing 82 and includes an expanded polystyrene or microporous polypropylene sheet 83 to each face of which a layer 84 of PVDF material is bonded, e.g. by an adhesive. The
PVDF layers 84 are oppositely polarised so that they operate in push-pull manner to bow the diaphragm when a signal is applied.
WHAT WE CLAIM IS:
1. An electro-acoustic transducer which includes a diaphragm assembly formed by a sandwich assembly of a sheet of a passive plastics material having on each of its faces a foil of a piezo-electric plastics material in which each said foil has surface electrodes and is electrically polarised so that movement of the diaphragm assembly generates potential differences between the electrodes of each of its foils, and vice versa, and in which the electrodes on said foils are coupled so that the two foils operate in pushpull.
2. A transducer as claimed in claim 1, and in which the passive sheet is made from an expanded polystyrene or microporous polypropylene sheet, the two piezo electric foils each being adhesive - bonded to one face of the passive sheet.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (4)
1. An electro-acoustic transducer which includes a diaphragm assembly formed by a sandwich assembly of a sheet of a passive plastics material having on each of its faces a foil of a piezo-electric plastics material in which each said foil has surface electrodes and is electrically polarised so that movement of the diaphragm assembly generates potential differences between the electrodes of each of its foils, and vice versa, and in which the electrodes on said foils are coupled so that the two foils operate in pushpull.
2. A transducer as claimed in claim 1, and in which the passive sheet is made from an expanded polystyrene or microporous polypropylene sheet, the two piezo electric foils each being adhesive - bonded to one face of the passive sheet.
3. A transducer as claimed in claim 1 or 2, and in which the piezo-electric dielectric is polyvinylidene fluoride.
4. An electro-acoustic transducer substantially as herein described with reference to the drawing accompanying the Provisional Specification.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB235680A GB1593272A (en) | 1977-09-13 | 1977-09-13 | Electro-acoustic transducers |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB235680A GB1593272A (en) | 1977-09-13 | 1977-09-13 | Electro-acoustic transducers |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1593272A true GB1593272A (en) | 1981-07-15 |
Family
ID=9738119
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB235680A Expired GB1593272A (en) | 1977-09-13 | 1977-09-13 | Electro-acoustic transducers |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB1593272A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2176673A (en) * | 1985-06-05 | 1986-12-31 | Reefgrade Limited | Electro-mechanical transducer diaphragm |
| FR2632474A1 (en) * | 1988-06-01 | 1989-12-08 | Saint Louis Inst | DEVICE FOR ACTIVE MITIGATION OF VIBRATION AND IN PARTICULAR NOISE WITHOUT ACOUSTIC RETARDATION |
-
1977
- 1977-09-13 GB GB235680A patent/GB1593272A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2176673A (en) * | 1985-06-05 | 1986-12-31 | Reefgrade Limited | Electro-mechanical transducer diaphragm |
| FR2632474A1 (en) * | 1988-06-01 | 1989-12-08 | Saint Louis Inst | DEVICE FOR ACTIVE MITIGATION OF VIBRATION AND IN PARTICULAR NOISE WITHOUT ACOUSTIC RETARDATION |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |