GB2047047A - Ultrasonic transducer - Google Patents
Ultrasonic transducer Download PDFInfo
- Publication number
- GB2047047A GB2047047A GB8011128A GB8011128A GB2047047A GB 2047047 A GB2047047 A GB 2047047A GB 8011128 A GB8011128 A GB 8011128A GB 8011128 A GB8011128 A GB 8011128A GB 2047047 A GB2047047 A GB 2047047A
- Authority
- GB
- United Kingdom
- Prior art keywords
- ultra
- face
- wedge
- sonic transducer
- layer
- 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- Withdrawn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
- 229910052751 metal Inorganic materials 0.000 claims abstract description 40
- 239000002184 metal Substances 0.000 claims abstract description 40
- 239000011888 foil Substances 0.000 claims abstract description 15
- 239000000463 material Substances 0.000 claims abstract description 7
- 239000004033 plastic Substances 0.000 claims abstract description 6
- 229920003023 plastic Polymers 0.000 claims abstract description 6
- 239000004020 conductor Substances 0.000 claims description 13
- 239000004411 aluminium Substances 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 6
- 239000000853 adhesive Substances 0.000 claims description 5
- 230000001070 adhesive effect Effects 0.000 claims description 5
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 5
- 239000013078 crystal Substances 0.000 claims description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 3
- 239000011777 magnesium Substances 0.000 claims description 3
- 229910052749 magnesium Inorganic materials 0.000 claims description 3
- 238000004544 sputter deposition Methods 0.000 claims description 3
- 239000002923 metal particle Substances 0.000 claims description 2
- 230000001154 acute effect Effects 0.000 claims 1
- 239000002245 particle Substances 0.000 claims 1
- 239000011248 coating agent Substances 0.000 description 7
- 238000000576 coating method Methods 0.000 description 7
- 230000005540 biological transmission Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229920002972 Acrylic fiber Polymers 0.000 description 2
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 229920005439 Perspex® Polymers 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/24—Probes
- G01N29/2487—Directing probes, e.g. angle probes
-
- 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
-
- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Health & Medical Sciences (AREA)
- Mechanical Engineering (AREA)
- Acoustics & Sound (AREA)
- Multimedia (AREA)
- Transducers For Ultrasonic Waves (AREA)
Abstract
An ultrasonic transducer is formed by a wedge 2 of plastics material having at least one face 12 coated with a thin layer of metal foil to which one face of a piezoelectric element 18 is adhered in electrical contact with the metal. A conductive pin 16 in the face 12 is also in contact with the metal layer. A cable supplying a voltage signal at ultra-sonic frequency to the element 18 has one lead 20 soldered to the pin 16 and another lead 22 soldered to the exposed face of the element. Thus the voltage signal is applied between opposite faces of element 18 without the need of a passage through the wedge to carry the lead 20. End face 14 of the wedge has ribs. <IMAGE>
Description
SPECIFICATION
Ultra sonic transducer
This invention concerns ultra-sonic transducers.
In known transducers a wedge of plastics material has a piezo-electric crystal element adhered to a face of the wedge. Conductors are soldered to opposite faces of the element so that voltage may be applied therebetween. Since one of these faces of the lement is adhered to the wedge, a passage must be formed through the wedge to receive one of the conductors.
One object of the invention is to provide an ultrasonic transducer in which the need for such a passage is obviated.
According to the invention an ultra-sonic transducer comprises a wedge of plastics material, a thin electrically conductive material layer on at least one face of the wedge, and a piezo-electric crystal element having a surface part attached to said layer in an electrically conductive manner such that a voltage can be applied to the element by means of a conductor electrically connected to the metal layer and another conductor electrically connected to another surface part of said element.
The wedge may be formed from acrylic plastics material which may be clear, for example PERSPEX (Trade Mark), and has at least one sloping face.
This sloping face has a thin layer of metal adhered thereto. The metal layer may be of metal foil, for example aluminium or magnesium foil. If desired one or more other faces of the wedge may also have a thin layer of metal thereon. We prefer not to coat a base face of the wedge through which ultra-sonic signals are to emerge from the transducer because (i) this face is usually in good acoustic coupling with a surface, often of metal, of an article being investigated by the ultra-sonic signals from the transducer and we believe the interposing of a metal layer between the base face and the article might be detrimental to the usually good transmission, and (ii) a thin metal coating on the base face may, in any case, be rubbed off quite quickly in use when that face is applied against the article.
A disc of piezo-electric crystal material has one or a first face adhered to the metal layer on the sloping face using a thin layer of adhesive, for example, cyroanylate. To establish electrical contact between the metal layer and the face of the disc thereadhered to, the adhesive may be doped with conductive metal powder, for example titanium powder, or preferably the disc can be pressed firmly against the metal so that some adhesive is displaced from between some areas of the disc face and the metal layer which thus makes direct contact with the disc face.
The opposite or second face of the disc has a conductor lead which may be conventionally soldered thereto. A pin which may be gold plated is fixed in the wedge, so as to be in electrical contact with the metal layer and anohter conductor lead is connected to the pin. Voltage at ulta-sonic frequency can thus be applied to the piezo-electric element using these two conductors so that the element generates an ultra-sonic signal at that frequency.
Besides avoiding the need to form a passage through the wedge to accommodate a conductor lead to the first face of the disc, we have found that the metal layer, in which the metal has high acoustic impedance, provides improved transmission of ultra-sonic signals between the piezo-electric element and the wedge. Initial theory suggested that to make use of the benefit of such high acoustic impedance, for satisfactory impedance coupling, the metal layer would have to have a thickness of at least one quarter of the wavelength of the ultra-sonic signal before the signal would "see" the layer and be transmitted through it. We discovered such a layer was too thick.We believe that for excellent transmission which appears to derive from surface effects on the surfaces of the metal layer, the thickness of the metal layer, for example the foil thickness, for a transducer operating at a frequency of about 4 to about 2 MHz should be about 0.0203 mm. (about 0.8 thousandths of an inch) to about 0.0254 mm. (about 1.0 thousandths of an inch).
Opposite the sloping face, the wedge may be formed with another sloping face formed with ridges and coated with the metal layer. This other face allows ultra-sonic signals impinging thereon within the wedge to escape from the wedge. Such ultrasonic signals are those which, due to internal reflection within the wedge, become separated from the main beam and could give rise to spurious noise effects.
It is also believed the metal coating improves reception by the piezo-electric disc of ultra-sonic signals reflected back into the wedge by the medium into which the signals were emitted from the wedge, in the sense that the reflected signals received by the piezo-electric element are remarkably free of high frequency noise signals. We believe that the metal layer between the wedge and piezo-electric element filters out high frequency noise signals.
Our investigations appear to show that by coating the wedge with a metal layer, the resultant transducer has an improved signal to noise ratio up to a depth of signal penetration of about 300 mm. into a standard steel test piece known per se.
Priorto adhering the foil layerto one or more faces of the wedge we prefer to coat each of those faces with an extremely thin sub-layer of deposited metal particles, for example pure aluminium, which can be deposited by sputtering to a thickness of about 400 microns after the conductor pin has been inserted into the wedge. The foil can then be adhered to the sub-layer in the same way as the piezo-electric disc is adhered to the foil so that electrical contact between the foil and sub-layer is ensured. We believe the use of a deposited sub-layer results in a better bond between the foil and the wedge.
The invention will now be further described with reference to a preferred example shown in the accompanying drawings, in which:
Figure 1 is a side elevation of a metal coated wedge to which a piezo-electric disc is adhered to form a transducer in accordance with the invention;
Figure 2 is a plan view of Figure 1 with parts omitted;
Figure 3 is an end view of the wedge in Figure 1;
Figure 4 is a section of an enlarged fragment of one end of the wedge in Figure land Figure 5 shows the wedge and piezo-electric disc encapsulated in a casing shown iri section.
Referring to Figures 1 to 4, a wedge is shown at 2 formed of plastics material, for example clear acrylic plastics, and coated with a thin metal layer except for its horizontal base face 4. This thin layer which can be about 0.0203 mm. to about 0.0254 mm. thick may be-aluminium or magnesium foil. The foil can be adhered directiy to the wedge or the foil may be adhered to a very thin sub-layer of pure aluminium previously deposited on the wedge to a thickness of about 400 microns by sputtering. The wedge has a base fiange 6, substantially vertical side faces 8, a horizontal top face 10 and sloping end faces 12 and 14. Prior to caoting the wedge with the layer or layers of metal a conduction pin 16 is secured in face 12 to make electrical contact with the applied coating.After coating, a piezo-electric disc 18, for example a PZT 5A has one face adhered to the metal coating on the face 12 so as to make electric contact with that coating.
This disc abuts against a ledge 20' on the flange 6.
An electrical lead 20 is soldered to the pin 16, whilst another electrical lead 22 is soldered to the exposed face of the disc 18.
The end face 14 may be formed with ribs or ridges 14a of triangular cross-section. The angle between adjacent ridges may be substantially 60 and the apex angle of each rib may be of a similar value.
Face 14 may be inclined at substantially 15 to the vertical. An indication of the dimensions of the wedge will be gained from the fact that its width between the faces 8 may be about 12 mm., its height between base face 4 and top face 10 may be about 12.7 mm. and the length of the base face 4 may be about 23 mm.
The face 14 allows internally reflected signals to escape.
So that the beam of emergent ultra-sonic signals from the base 4 may be at angle B = 45" to the normal to the base, the face 12 may be at angle A = 37.5 to the horizontal, for angle B to be 60 angle A may be 47.5 , and for B to be 70" angle A may be 53 .
The wedge 2 with the piezo-electric disc 18 thereon may be potted using epoxy resin or other resin 24 in a plastics, for example, styrene, casing 26 from which emerges cable 28 providing leads 20 and 22.
In order to achieve a correct pulse shape and avoid showing up noise on reception when using conventional transducers, a receiver receiving signals from a known transducer has to be tuned to give optimum results. In the case of the transducer formed according to the invention and as described above, no tuning is needed, but an inductance may be included in the circuit in the casing 26 to counteract the effects of the cable.
Claims (15)
1. An ultra-sonic transducer comprising a wedge of plastics material, a thin electrically conductive metal layer on at least one face of the wedge, and a piezo-electric crystal element having a surface part attached to said layer in an electrically conductive manner such that a voltage can be applied to the element by means of a conductor electrically connected to the metal layer and another conductor electrically connected to another surface part of said element.
2. An ultra-sonic transducer as claimed in claim 1, in which the piezo-electric element is attached to the metal layer by adhesive.
3. An ultra-sonic transducer as claimed in claim 2, in which the adhesive contains electrically conducting particles.
4. An ultra-sonictransducer as claimed in any one preceding claim, in which the metal layer is formed of metal foil adhered to the wedge.
5. An ultra-sonic transducer as claimed in claim 4, in which the metal is aluminium or magnesium.
6. An ultra-sonic transducer as claimed in any one preceding claim, in which the first mentioned conductor is connected to a conducting pin in electrical contact with the metal layer.
7. An ultra-sonic transducer as claimed in any one preceding claim in which the metal layer is about 0.0203 mm. to about 0.0254 mm. thick.
8. An ultra-sonic transducer as claimed in claim 4, or claim 5 or as claimed in claim 4 and claim 7 or as claimed in claim 5 and claim 7, in which the foil is adhered to a thinner sub-layer of metal particles deposited on the wedge.
9. An ultra-sonic transducer as claimed in claim 8, in which the sub-layer is deposited by sputtering.
10. An ultra-sonic transducer as claimed in claim 8 or claim 9, in which the sub-layer is aluminium.
11. An ultra-sonic transducer as claimed in any one of claims 8 to 10, in which the sub-layer is about 400 microns thick.
12. An ultra-sonictransducer as claimed in any one preceding claim, in which said face of the wedge is sloping in relation to a base face of the wedge, through which base face ultra-sonic signals are to be emitted or received by the transducer.
13. An ultra-sonic transducer as claimed in claim 12 in which the wedge has another sloping face which is at acute angle to the base face, said other sloping face being a ribbed end face.
14. An ultra-sonic transducer as claimed in claim 13 when claim 12 appended to any one of claims 1 to 7 in which the ribbed face is also coated with the thin metal layer, or an ultra-sonic transducer as claimed in claim 13 when claim 12 is appended to any one of claims 8 to 11 in which the ribbed face is also coated with a said metal foil on a said sub-layer.
15. An ultra-sonictransducer substantially as hereinbefore described with reference to the accompanying drawing.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8011128A GB2047047A (en) | 1979-04-04 | 1980-04-02 | Ultrasonic transducer |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7911739 | 1979-04-04 | ||
| GB8011128A GB2047047A (en) | 1979-04-04 | 1980-04-02 | Ultrasonic transducer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2047047A true GB2047047A (en) | 1980-11-19 |
Family
ID=26271118
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8011128A Withdrawn GB2047047A (en) | 1979-04-04 | 1980-04-02 | Ultrasonic transducer |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2047047A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0025215A2 (en) * | 1979-09-11 | 1981-03-18 | Siemens Aktiengesellschaft | Contact for an ultrasonic transducer |
| EP0284689A2 (en) * | 1987-03-31 | 1988-10-05 | Suzuko Precision Ind. Co., Ltd. | Ultrasonic probe |
| WO2002042762A1 (en) * | 2000-11-22 | 2002-05-30 | Agfa Ndt Gmbh | Ultrasonic probe, in particular for manual inspections |
| CN102778511A (en) * | 2011-05-13 | 2012-11-14 | 中国石油天然气股份有限公司 | Ultrasonic guided wave transducer for flat nondestructive testing |
-
1980
- 1980-04-02 GB GB8011128A patent/GB2047047A/en not_active Withdrawn
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0025215A2 (en) * | 1979-09-11 | 1981-03-18 | Siemens Aktiengesellschaft | Contact for an ultrasonic transducer |
| EP0025215A3 (en) * | 1979-09-11 | 1981-07-01 | Siemens Aktiengesellschaft | Contact for an ultrasonic transducer |
| EP0284689A2 (en) * | 1987-03-31 | 1988-10-05 | Suzuko Precision Ind. Co., Ltd. | Ultrasonic probe |
| EP0284689A3 (en) * | 1987-03-31 | 1990-07-04 | Suzuko Precision Ind. Co., Ltd. | Ultrasonic probe |
| WO2002042762A1 (en) * | 2000-11-22 | 2002-05-30 | Agfa Ndt Gmbh | Ultrasonic probe, in particular for manual inspections |
| US6641535B2 (en) | 2000-11-22 | 2003-11-04 | Agfa Ndt Gmbh | Ultrasonic probe, in particular for manual inspections |
| CN102778511A (en) * | 2011-05-13 | 2012-11-14 | 中国石油天然气股份有限公司 | Ultrasonic guided wave transducer for flat nondestructive testing |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3794866A (en) | Ultrasonic search unit construction | |
| CA1134939A (en) | Polymeric piezoelectric microprobe having a damper | |
| US5545942A (en) | Method and apparatus for dissipating heat from a transducer element array of an ultrasound probe | |
| EP0397959B1 (en) | Annular array sensors | |
| CA1145451A (en) | Coupling for a focused ultrasonic transducer | |
| EP0196652B1 (en) | A backing material for an ultrasonic transducer | |
| US4409510A (en) | Method for providing ultraacoustic transducers of the line curtain or point matrix type and transducers obtained therefrom | |
| US5559388A (en) | High density interconnect for an ultrasonic phased array and method for making | |
| US4698541A (en) | Broad band acoustic transducer | |
| US20130257226A1 (en) | Signal return for ultrasonic transducers | |
| US2875354A (en) | Piezoelectric transducer | |
| US5541468A (en) | Monolithic transducer array case and method for its manufacture | |
| EP0142215A2 (en) | Ultrasound transducer with improved vibrational modes | |
| US5155708A (en) | Acoustic wave sensor and method of making same | |
| US4482834A (en) | Acoustic imaging transducer | |
| GB2047047A (en) | Ultrasonic transducer | |
| EP0589648A1 (en) | Ultrasonic transducers | |
| US4443733A (en) | Tapered wave transducer | |
| JPH06101879B2 (en) | Aerial ultrasonic transducer | |
| JPH07322393A (en) | Ultrasonic probe | |
| US6321438B1 (en) | Method of applying a matching layer to a transducer | |
| JPH0323040B2 (en) | ||
| JPH0746694A (en) | Ultrasonic transducer | |
| JPH071920Y2 (en) | Ultrasonic transducer | |
| US4034317A (en) | Ultrasonic delay lines and method of making the same |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |