GB2336967A - Piezoelectric transducer made from preformed mouldings of acoustic material around the vibrating element - Google Patents
Piezoelectric transducer made from preformed mouldings of acoustic material around the vibrating element Download PDFInfo
- Publication number
- GB2336967A GB2336967A GB9809435A GB9809435A GB2336967A GB 2336967 A GB2336967 A GB 2336967A GB 9809435 A GB9809435 A GB 9809435A GB 9809435 A GB9809435 A GB 9809435A GB 2336967 A GB2336967 A GB 2336967A
- Authority
- GB
- United Kingdom
- Prior art keywords
- transducer
- acoustic
- assembly
- mouldings
- transducer assembly
- 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.)
- Withdrawn
Links
- 238000000465 moulding Methods 0.000 title claims abstract description 28
- 239000012814 acoustic material Substances 0.000 title abstract 2
- 230000008878 coupling Effects 0.000 claims abstract description 3
- 238000010168 coupling process Methods 0.000 claims abstract description 3
- 238000005859 coupling reaction Methods 0.000 claims abstract description 3
- 239000000463 material Substances 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 10
- 150000001875 compounds Chemical class 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 238000004382 potting Methods 0.000 claims description 5
- 239000003990 capacitor Substances 0.000 abstract description 2
- 239000004830 Super Glue Substances 0.000 description 4
- FGBJXOREULPLGL-UHFFFAOYSA-N ethyl cyanoacrylate Chemical compound CCOC(=O)C(=C)C#N FGBJXOREULPLGL-UHFFFAOYSA-N 0.000 description 4
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 3
- 239000003063 flame retardant Substances 0.000 description 3
- 239000007799 cork Substances 0.000 description 2
- 238000013016 damping Methods 0.000 description 2
- 229920001971 elastomer Polymers 0.000 description 2
- -1 polyethylene Polymers 0.000 description 2
- 229920000459 Nitrile rubber Polymers 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000004005 microsphere Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000002991 molded plastic Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229920001084 poly(chloroprene) Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000007781 pre-processing Methods 0.000 description 1
- 238000005476 soldering Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
- B06B1/0644—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element
- B06B1/0651—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element of circular shape
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
- B06B1/0644—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element
- B06B1/0662—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element with an electrode on the sensitive surface
- B06B1/067—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element with an electrode on the sensitive surface which is used as, or combined with, an impedance matching layer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
- B06B1/0644—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element
- B06B1/0662—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element with an electrode on the sensitive surface
- B06B1/0681—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element with an electrode on the sensitive surface and a damping structure
- B06B1/0685—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element with an electrode on the sensitive surface and a damping structure on the back only of piezoelectric elements
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
- B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
- B06B2201/00—Indexing scheme associated with B06B1/0207 for details covered by B06B1/0207 but not provided for in any of its subgroups
- B06B2201/50—Application to a particular transducer type
- B06B2201/55—Piezoelectric transducer
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Transducers For Ultrasonic Waves (AREA)
Abstract
An electro acoustic transducer is manufactured by taking a transducer assembly having at least one piezoelectric element 2, electrodes contacting the element 4,6 and acoustic loading blocks 6, and applying successive superposed layers of separately preformed mouldings 20,37,32,34,36 of differing acoustic properties around the transducer assembly to provide a moulded transducer. Electrical coupling is maintained between the transducer and the exterior of the unit by cable 28, and a transformer 24 and PCB assembly 26, containing for example thermistor or tuning capacitor, may be provided. At least one matching layer 34 is provided across the radiating surface of the transducer and at least one isolating layer 36 is provided around the rest of the unit inside the casing 38. Successive layers of acoustic material generally have alternating degrees of hardness.
Description
MOLDED TRANSDUCERS 2336967 This invention relates to electro-acoustic
transducers used for example in acoustic pulse-echo ranging systems.
Such transducers are typically piezoelectric in operation, with one or more piezoelectric elements and associated contact electrodes clamped between loading blbcks to provide a relatively high-Q assembly that will oscillate at a predetermined frequency when excited by an alternating electric potential at that frequency so as to transmit acoustic energy. The same transducer is commonly used to receive reflected acoustic energy at that frequency and convert it back to electrical energy.
Since the potential required to excite such transducers are typically quite high, and they are high impedance devices, and may need to be located some distance from a transceiver which generates the excitation signal and processes received signals, they are usually associated with an impedance matching transformer and possibly also with temperature sensing components and preamplifying or preprocessing circuits for received signals. Furthermore, it is usually necessary tb provide acoustic matching between the transducer assembly and a surrounding medium, usually gaseous, to provide the transducer assembly with suitable directional properties, to protect the transducer assembly from the surrounding medium, and to isolate the transducer assembly as far as possible from the structure an which it is mounted.
The above requirements must be accommodated by the enclosures applied to house such transducers. Typically, the transducer assembly is wrapped on its non-radiating surfaces with a material such as cork, and placed in a moulded or fabricated metallic or moulded plastic shell which may be selectively lined with material such as cork and is then filled with a potting compound so as to embed the transducer assembly. The shell may be open on a side corresponding to the radiating surface of the transducer, in which case a layer or layers of acoustic matching material may be cast into the shell so as 2 to cover the radiating surface of the assembly, or it may be closed by a thin diaphragm at that surf ace, in which case matching material must be installed within the diaphragm prior to inserting and potting the transducer. In either case, the assembly process is slow, labourious, labour intensive, and must be carefully controlled so that components are properly located within the shell. The installation of transformers and other electronic components further complicates the process.
io Typical transducers are described in U.S. Patent No. 3,674,945 (Hands) and 5,339,292 (Brown et al), With the object of providing an improved technique for packaging acoustic transducers which simplifies and improves control over the assembly process, we have proposed in our copending application no. 9722466.1, a method of manufacturing an electro-acoustic transducer comprising forming a transducer assembly comprising at least one piezoelectric element, electrodes contacting the element, and acoustic loading blocks, and moulding successive layers of material of differing acoustic properties around said transducer assembly to provide a moulded transducer, while maintaining electrical coupling between the transducer assembly and the exterior of the transducer, the moulded layers providing at least one acoustic matching layer covering a radiating surf ace of the transducer assembly, a casing surrounding the remainder of the transducer assembly, and at least one layer of acoustic isolating material between the casing and the transducer assembly.
1 have found that a yet further improved assembly technique 30 can be achieved by independently forming each of the successive layers as separate mouldings, and then assembling the moulding successively around the transducer to obtain the finished assembly.
3 The invention is described further with reference to the accompanying drawing, in which Figure 1 is a cross-section through an exemplary embodiment of transducer manufactured in accordance with the invention.
The manufacture of a transducer in accordance with the invention will be described with reference to Figure 1.
A first stage in manufacture is the assembly of a transducer assembly comprising a ceramic piezo-electric transducer element 2 secured between an aluminum driver block 4 and a steel loading block 6 by a machine screw 8 engaging a threaded socket 10 in the block 4 and bearing on the block 6 through an electrically insulating washer assembly 12 which includes an insulating sleeve 14 surrounding the stem of the screw where it passes through the block 6. The element 2 and the masses of the blocks 4 and 6 are selected so that the assembly will have a desired resonant frequency typically in the low ultrasonic range.
In order to provide electrical connection to the assembly, rigid wires 16 and 18 are spot welded respectively to the block 6 and the head of the screw 8 so as to project upwardly from the top (as shown in the drawing) of the transducer assembly, In the next stage, the assembly is inserted into a moulding forming a damping layer 20 of relatively soft polymer. The moulding envelopes the upper portion of the assembly except for the side and bottom surfaces of the block 4, the bottom surface of which is the radiating surface of the transducer assembly. The layer 20 has an external configuration which is generally cylindrical except for a shelf 22 at its top end through which the wires 16 an 18 protrude. The moulding providing the layer 20 may be moulded for example from flame retardant nitrile rubber of 25 durometer hardness. The moulding is adhered to the4 side surfaces of the block 6 4 using a cyanoacrylate adhesive applied to the surfaces prior to assembly.
Following this stage, a toroidal matching transformer 24 is located coaxially with the assembly above a small printed circuit board 26 secured on the shelf beneath the transformer by soldering the wires 16 and 18 to it. Connections from the primary and secondary of the transformer are also soldered to the board, to which the conductors of a lead-in cable 28 are also secured. The board also carries such components as a tuning capacitor, a temperature sensing thermistor and other small components associated with matching the transducer to the line through the transformer, as well as establishing connections between the various components. The configuration of the transformer and associated components may be in accordance with known practice, for example as disc losed in U.S. Patent No. 5,347,495 (Cherek et al), and forms no part of the present invention beyond the necessity to accommodate components thereof in the transducer. This stage completes electrical assembly of the transducer.
In a following stage, further mouldings 32, 34 of harder rubber are applied to the loading block 4, again using cyanoacrylate adhesive, the moulding 32 having an upwardly extending cylindrical skirt 35 such as to surround the entire assembly, except for the distal portion of cable 28. In the example shown, the mouldings 32 is of 25 durometer hardness flame retardant rubber, for example a blend of polychloroprene and E.P.D.M. The moulding 34 covers the bottom face of the block 4 to form an acoustic matching layer as described further in the Hands and Brown et al patents referenced above. The properties required in the matching layer formed by moulding 34 are different from those required in the layer formed by moulding 32, since it must both provide appropriate acoustic matching as well as being resistant to hostile environments and flame retardant. An example of a suitable material is a chlorosulphonated polyethylene sold under the trademark HYPOLON by DuPont, whose density is reduced by admixture of glass microspheres, and which has a durometer hardness of 85. If the transducer is to be utilized in a particularly aggressive atmosphere, it is possible to cast in a very thin diaphragm (not shown) of stainless steel or other resistant material beneath the layer 34 to protect the radiating face of the latter. The moulding 34 is adhesively secured using cyanoacrylate adhesive to the radiating face of block 4.
Next, a further damping layer in the form of a moulding 36, 10 typically of similar material as the layer 20 but of 70 durometer hardness, is applied around the layer 32, to which it is adhered using cyanoacrylate adhesive.
The free space 37 within the Skirt 35 and around the electronic components is then filled with a potting compound so as to secure these components into a solid block. The compound is injected through a port 39, the space being vented through a port 41.
Finally the assembly with the mouldings applied is inserted into an external casing 38 in form of an outer generally cylindrical shell moulded from rigid synthetic resin such as polypropylene or polyvinylidene fluoride such that a strain relief portion 40 of the layer 36 around the cable 28 emerges through an opening of the top of the casing. The casing 38 may be moulded with a mounting thread 42. The casing 38 is formed with barbed ribs 43 to retain the moulding 36.
Particularly since the layers 32 and 34 are moulded separately. none of the mouldings applied to the transducer assembly completely envelopes the assembly produced by the preceding stage, thus facilitating. As well as being adhered to the block 4, the moulding 32 is also adhered to the mouldings 32 and 36 so as, together with the potting compound in cavity 37, to seal in the transducer completely.
6 It will be noted that successive superposed layers of moulded material between the cylindrical wall of the casing 38 have in general alternating degrees of hardness, thus contributing to isolating the active components of transducer acoustically from its outer casing.
7
Claims (6)
- CLAIMS:A method of manufacturing an electro-acoustic transducer comprising forming a transducer assemblylat least one piezoelectric element, electrodes - contacting the element, and acoustic loading blocks, and applying successive superposed preformed mouldings of material of differing acoustic properties around said transducer assembly to provide a moulded transducer, while maintaining electrical coupling between the transducer assembly and the exterior of the transducer, the mouldings providing at least one acoustic matching layer covering a radiating surface of the transducer assembly, a casing surrounding the remainder of the transducer assembly, and at least one layer of acoustic isolating material between the casing and the transducer assembly.
- A method according to claim 1, wherein successively applied mouldings are shaped such that they do not completely envelope the assembly thus allowing for easy application to the assembly of the mouldings used to form those layers.
- 3. A method according to claim 2, wherein superposed mouldings applied around the transducer assembly within a cylindrical wall of the casing have alternating degrees of hardness.
- 4. A method according to claim 1, 2 or 3, wherein certain of the preformed mouldings are conf igured to leave a cavity around electronic components of the transducer assembly, and the cavity is filled with a potting compound.
- 5. A method of manufacturing an electro-acoustic transducer, substantially as hereinbefore described with reference to the accompanying drawing.8
- 6._ An electro-acoustic transducer manufactured by the method of any one of the preceding claims.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9809435A GB2336967A (en) | 1998-05-01 | 1998-05-01 | Piezoelectric transducer made from preformed mouldings of acoustic material around the vibrating element |
| US09/178,699 US6166998A (en) | 1997-10-24 | 1998-10-26 | Moulded transducer |
| CA002251395A CA2251395C (en) | 1997-10-24 | 1998-10-26 | Moulded transducer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9809435A GB2336967A (en) | 1998-05-01 | 1998-05-01 | Piezoelectric transducer made from preformed mouldings of acoustic material around the vibrating element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9809435D0 GB9809435D0 (en) | 1998-07-01 |
| GB2336967A true GB2336967A (en) | 1999-11-03 |
Family
ID=10831377
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9809435A Withdrawn GB2336967A (en) | 1997-10-24 | 1998-05-01 | Piezoelectric transducer made from preformed mouldings of acoustic material around the vibrating element |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2336967A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1909078A1 (en) * | 2006-09-28 | 2008-04-09 | VEGA Grieshaber KG | Piezoelectrically excitable oscillation device |
| CN106140593A (en) * | 2015-04-20 | 2016-11-23 | 无锡德众超声技术有限公司 | There is the ultrasonic transducer of vibration-damping function |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3826799A1 (en) * | 1988-08-06 | 1990-02-08 | Swf Auto Electric Gmbh | Ultrasonic transducer |
| GB2260059A (en) * | 1991-09-27 | 1993-03-31 | Federal Ind Ind Group Inc | Piezoelectric acoustic transducer |
| GB2330724A (en) * | 1997-10-24 | 1999-04-28 | Federal Ind Ind Group Inc | Method of manufacturing an electro-acoustic transducer |
-
1998
- 1998-05-01 GB GB9809435A patent/GB2336967A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3826799A1 (en) * | 1988-08-06 | 1990-02-08 | Swf Auto Electric Gmbh | Ultrasonic transducer |
| GB2260059A (en) * | 1991-09-27 | 1993-03-31 | Federal Ind Ind Group Inc | Piezoelectric acoustic transducer |
| GB2330724A (en) * | 1997-10-24 | 1999-04-28 | Federal Ind Ind Group Inc | Method of manufacturing an electro-acoustic transducer |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1909078A1 (en) * | 2006-09-28 | 2008-04-09 | VEGA Grieshaber KG | Piezoelectrically excitable oscillation device |
| CN106140593A (en) * | 2015-04-20 | 2016-11-23 | 无锡德众超声技术有限公司 | There is the ultrasonic transducer of vibration-damping function |
| CN106140593B (en) * | 2015-04-20 | 2020-05-19 | 无锡德众超声技术有限公司 | Ultrasonic transducer with vibration damping function |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9809435D0 (en) | 1998-07-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |