A therapeutic applicator for ultrasound

Abstract

 In a therapeutic applicator for the administration of ultrasound a piezoelectric crystal (56) is connectable through a conventional three-wave washer (53) to an electrical power source. The washer (53) is sandwiched between the crystal (56) and a circuit board (46) to which it is attached at one spot on its side towards the board (46). The convolutions on the opposite side of the washer (53) define a plurality of radially equispaced zones for electrical contact with an electrode on the crystal. The contacts are displacable radially outwardly with respect to the point of attachment under dynamic load. A simple but effective and consistent electrical connection is established for an applicator which is easy to assemble.

Description

FIELD OF THE INVENTION

[0001] This invention relates to an ultrasonic frequency generator. More particularly but not exclusively, the invention concerns mounting an ultrasonic frequency generating crystal in therapeutic ultrasonic applicators.

BACKGROUND OF THE INVENTION

[0002] Ultrasonic frequency radiation has long been known to be valuable in deep tissue therapy. Radiation at ultrasonic frequencies is known to produce effects such as heat, intracellular micro-stirring and to increase diffusion rates of fluids in tissues. These effects can initiate or accelerate the complex metabolic and physiological processes involved in healing and tissue repair. It is important to control and predetermine the ultrasonic frequency generated for such therapy since the ability of the tissues to absorb the radiation varies according to the frequency. Also, deeper tissue therapy requires a lower frequency to avoid over-dosage of tissues closer to the generator.

[0003] Ultrasonic radiation is extensively used, in a process known as diathermy, in muscular therapy. Ultrasonic diathermy involves the application of low intensity ultrasonic vibrations in the 1 megacycle band to muscular tissue.

[0004] The physiological effects of ultrasonic radiation have been widely studied. Examples of such studies include the publications by Gersten, J. et al., Changes in Phosphocreatine Produced in Striated Muscle by Ultrasound., Am. J. Phys. Med. 33:4, (Aug.) 1954 and by Reese, E., Clinical Aspects of Ultrasound, Intl. Rev. Phys. Med., (June) 1957.

[0005] Ultrasonic treatment in diathermy and deep tissue therapy is usually administered to a patient by way of an applicator. An applicator having a larger surface is typically required for diathermy, to treat muscle groups, whereas a smaller surface is preferable for localized, more specific tissue treatment. The applicator for the latter treatment is often portable and hand-held. The ultrasonic radiation may be generated by a transducer, for example, a piezoelectric crystal, carried at a head of the applicator. The applicator is usually placed against the skin of the patient in the region to be treated. A fluid is typically applied to the skin before administering the ultrasonic radiation. The fluid couples the transducer to the skin to enhance the transmission of ultrasonic energy and electrical stimuli and to encourage any biofeedback. Oil is effective, particularly in diathermy. Many colloidal gels are available which are specifically useful in deeper tissue therapy.

[0006] Ultrasound is used in a number of other medical and veterinary applications. It is used in medical diagnostics, in microsurgery and even to cut bone. Some of these applications and techniques are described in the work by P.N.T. Wells, Biomedical Ultrasonics, Academic Press, 1977.

[0007] Ultrasound is also used to clean equipment. Dirt and other contaminating particles are very effectively dislodged from lensed or delicate instruments and from heat-labile materials. Ultrasound generated in an immersion fluid bath cleans by cavitation. For example, metal oxides and stains are removed by cavitation and it loosens plaster from equipment or materials immersed in the fluid bath. The transducers, which convert electrical energy to ultrasonic radiation, are commonly mounted on the walls of the cleaning tank so that the ultrasonic waves are radiated directly into the cleaning fluid. The substance targeted to receive the ultrasonic radiation is known as the load. In this instance, the fluid is the load.

[0008] Various kinds of apparatus are known whereby vibratory energy is applied to the surface of a human body. In this instance, the patient is the load. One example of such apparatus is shown in U. S. Patent 4,583,529 issued to Briggs. The ultrasonic therapy device shown in that patent is able to be held in the hand. It has a power-mode selector for varying the ultrasonic frequency to be applied and a time selector for limiting or indicating the duration of the treatment. A piezoelectric crystal comprises the transducer. The crystal is fixed to the head of the applicator by conventional means such as plastic cement or epoxy resinous adhesive material.

[0009] A difficulty long associated with ultrasonic applicators similar to that described by Briggs is the electrical connection of the transducer to a power source. The difficulty arises because of the vibratory or oscillatory nature of ultrasonic radiation generation. The electrical connection can be broken due to oscillation of the transducer, particularly if the transducer is a piezoelectric crystal. The crystal is often relatively thin and the effects of oscillation are magnified with respect to any electro-mechanical connection to the crystal. Stress caused by oscillation can loosen or break the connection.

[0010] Many attempts have been made to overcome this difficulty. One such attempt is described in U. S. Patent 3,025,419 to Mettler. This patent shows an ultrasonic frequency generating crystal assembly which incorporates an effective but simple and inexpensive means of electrically connecting the crystal to the power supply. The applicator device has a crystal coated in a particular manner with an electrically conductive material. The crystal has a first coating or plating of conductive material, such as silver, on one surface. The diameter of the first coating is smaller than the diameter of the crystal. A second conductive coating of silver is applied over the entire opposite surface and extends part-way around the sides of the crystal, which is disc-shaped. The conductive coatings are thus separated by an unplated margin. The crystal is set in a mounting head for the applicator. The head may be cup-shaped and dimensioned to receive the crystal. A conductive adhesive such as that epoxy material commonly known as "cold solder" is used to bond the crystal circumferentially to the mouth of the head. The cold solder provides an electrical connection between the conductive coatings and the mounting head. It affords a dependable, sealed mechanical connection for holding the crystal in the head.

[0011] Various other ways of mounting a transducer have been proposed. In U.S. Patent No. 3,794,866, a testing system including a crystal with acoustical damping is shown. The crystal is enclosed in a housing and electrical supply leads are connected directly to electrodes on the opposed major surfaces of the crystal. U.S. Patent No. 3,821,834 is similar and further relates to a method of manufacturing a search unit for the testing system. The crystal is mounted on the housing by an epoxy resin. U.S. Patent No. 3,950,660 relates to the search unit mentioned in the preceding patent.

[0012] U.S. Patent Nos. 3,403,271 and 3.278,771 are further examples of piezoelectric elements cemented or otherwise glued on a housing. U.S. Patent Nos. 3,206,558 and 3,749,854 are illustrative of other uses of piezoelectric elements. U.S. Patent No. 3,672,462 is another example of a transducer mounted in apparatus for sonic energy distribution.

[0013] Another type of electrical connection for the transducer makes use of a spring. Such a connection is shown generally in the illustration on page 346 of the work by Julian R. Fredrick, Ultrasonic Engineering, 1965. Other examples are shown on pages 63 and 64 of the work by Wells previously mentioned. A spring is electrically connected between the power source and the crystal in applicators of this type. The spring is resiliently flexible and can therefore accommodate the bending moments developed on oscillation of the crystal.

[0014] In the most commonly used spring connector, a helical compression spring is held centered in a steel cup by an epoxy adhesive. One end of the spring is adhered to the bottom of the cup. The other end of the spring abuts the crystal which holds the spring in compression. The crystal is bonded to the applicator by a circumferential bead of epoxy. This kind of connection, however, has been found to be wanting in certain respects.

[0015] The amount of epoxy used to center the spring in the cup varies since the connector is assembled by hand. Excessive adhesive can immobilize the spring. The spring rate can be affected to an extent which renders it substantially inflexible, the benefits derived from employing a flexible connector being thereby eliminated. The effectiveness of the spring as connector is therefore inconsistent. Effectiveness varies from one applicator to another, depending upon the amount of epoxy used.

[0016] Moreover, it is difficult to ensure that the end of the spring remains parallel to the crystal when bonding the crystal to the cup. This can cause the spring to bend or cock on assembly, reducing the amount of spring material contacting the crystal. The electrical connection is thereby impaired. The assembler is often oblivious of such impairment.

[0017] Also, the diameter of a compression spring is such that it contacts the crystal at one, or at best two, points under dynamic loading. A spring makes random contact with the oscillating crystal. Undue wear on the crystal electrode can result. Finally, the use of epoxy to load the spring between the cup and crystal is time consuming in addition to being inconsistent.

[0018] It is accordingly desirable to provide an electrical connection for the transducer of an ultrasonic generator which minimizes the above difficulties associated with known arrangements.

SUMMARY

[0019] These and other needs and purposes are usefully addressed in the present invention wherein an ultrasonic frequency generator or applicator comprises a body having a piezoelectric crystal as transducer at a head remote from a power source for the applicator, and an electrical contact member between the crystal and power source, said contact member being convoluted and electrically connected to the power source by one such convolution to one side of the contact member and to the crystal by at least one other convolution to the opposite side of the contact member.

[0020] The contact member may be a three-wave washer of the conventional kind in which a flat metal annulus forming the washer is stabbed or stamped in one direction at three equidistant points to form the convolutions.

[0021] With a wave washer as contact member, the outer surface on one side of the washer may be connected to the power source and the outer surface of at least one of the convolutions to the opposite side of the washer may establish the electrical connection with the crystal. Preferably, all the other convolutions are in electrical contact with the crystal, thereby providing a plurality of spaced contact zones.

[0022] A conductive coating may be formed on the surface of the crystal toward the washer, at least in the zone of electrical connection.

[0023] Preferably, a suitably conductive material such as silver is formed on the crystal as a circular plating of greater diameter than that of the washer.

[0024] With this arrangement, a small air gap may be present between the washer convolutions and the crystal. The gap is sufficiently small, however, to establish and maintain the electrical connection upon oscillation of the transducer. Should the gap between one convolution and the crystal be enlarged on oscillation, the contact provided by at least one other convolution is maintained due to the structural configuration of the washer. The convolutions form spaced apart protrusions towards the crystal. Should oscillation cause the crystal to move away from one contact, it would, of course, move closer to another. A simple and consistent electrical connection for the transducer is formed with the above arrangement.

[0025] In one form of generator according to the invention, a printed circuit board establishes electrical contact between the washer and a source of electrical power. Preferably, an impedance matching transformer is disposed on the side of the printed circuit board opposite the washer, the washer being connected, via the board, to leads forming the secondary windings of a wound transformer.

[0026] The transformer may be sandwiched between a pair of printed circuit boards, the live lead of a coaxial cable connectable to the power supply being connected, via the board disposed inwardly of the body, to leads forming the primary windings of the transformer.

[0027] A mounting cup or shield is provided for the electrically connected crystal. The cup is preferably screw threadable on the head for convenience and simplicity of assembly and for grounding the applicator.

[0028] Once the appropriate electrical connections have been made with the shield exteriorly of the body, the transducer assembly is easily mounted, by appropriate rotation, on the head. Assembly of an ultrasonic generator in this manner minimizes opportunity for inconsistency in construction.

[0029] It will, of course, be understood that the applicator can be grounded in any one of a number of convenient ways. As one example, the ground lead of the coaxial cable can be connected to the metal mounting shield. The periphery of the shield contacts a core to ground the applicator when the transducer assembly is mounted on the head.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] These and other features and advantages of this invention will be appreciated as the same becomes better understood with reference to the following description of presently preferred embodiments of the invention, which description is presented with reference to the accompanying drawings in which:

FIG. 1 is a longitudinal cross-sectional view of a preferred embodiment of a therapeutic applicator equipped with an ultrasonic frequency generator according to the invention;

FIG. 2 is a front elevational view of an alternative form of crystal for use as a transducer in an ultrasonic therapeutic applicator of the invention;

FIG. 3 is a side elevational view of the transducer of FIG. 2;

FIG. 4 is an exploded perspective view illustrating the components, but for the crystal and mounting means, of an embodiment of a transducer assembly according to the invention;

FIG. 5 is a side elevational view of the assembled components of FIG. 4;

FIG. 6 is a bottom plan view of the components shown in FIG. 5.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0031] Referring to the drawings, an applicator 10 suitable for the therapeutic administration of ultrasonic radiation includes a body in the form of a handle 11. The applicator has a forward end comprising a head 12 equipped with an ultrasonic frequency generating crystal 56. A coaxial cable 14 is attached at the rearward end of the handle. The cable carries a screw-threadable sleeve connector 16 at its free end remote from the handle. The connector 16 is of the kind conventionally used to couple coaxial cables to an electrical power supply by a distal locating sleeve 18 and a proximal locking sleeve 20. The locating sleeve is adapted to be connected first to an externally screw threaded power outlet plug (not shown). The locking sleeve is thereafter tightened to abut and thereby lock the locating sleeve on the plug.

[0032] The cable is secured to the applicator by a flexible connector 22 at the rear of the handle which has a rigidly flexible end portion 23 to protect the cable in use and a lockable nut 24 for screw threadable attachment of a coupling portion to the handle. The coupling portion is sheathed in an insulating and coupling tape 26 for threaded connections. Commonly available tape made from Teflon is appropriate.

[0033] The applicator has an outer casing 28 which is preferably made from a suitable insulating polymeric plastics material. The casing surrounds an inner thermally insulating core 30. The core may be formed from any one of a number of materials selected for their insulating and protective shielding properties. Either naturally occurring or synthetic materials may be suitable. Some metals, such as lead, are suitable. Many insulated synthetic resinous materials would also be suitable. Generally, the core material would be selected to have heat shielding capability as well as electrical insulating properties. The core may be a heat insulator for the applicator to ensure comfort in operation. A metal such as aluminum is shown as the core material in the embodiment illustrated. Using aluminum to form the core of the applicator provides a heat sink to dissipate excess heat generated by the transducer. In this way, the transducer is maintained at a cool temperature and is comfortable to a patient. In addition, the aluminum core provides a shielding to the coaxial cable and protects the user from harmful frequencies, for example, frequencies in the radio range. Also, the metal aluminum core is conductive and enables the applicator to be grounded.

[0034] The core has a central passage 32 to carry the coaxial cable. The passage is enlarged towards the head of the applicator and screw threaded to receive a transducer assembly 33.

[0035] The transducer assembly 33 is receivable on the head of the applicator handle. The transducer assembly includes a transducer shield cup 34 which has a gland 36 for the passage of the leads of the coaxial cable through the inner wall of the cup. The exposed end of the ground lead 38 of the cable is attached to the cup. The exposed end of the live cable lead 40 is soldered to a first printed circuit board 42 of the assembly. The shield cup is of a diameter slightly less than that of the board 42 and the two are circumferentially soldered one to another.

[0036] The assembly also includes an impedance matching transformer 44 sandwiched between board 42 and a second printed circuit board 46. A nylon standoff 48 or other appropriate spacer is disposed in the central aperture of the wound transformer. A bore of the standoff is oppositely screw threaded to receive mounting screws 50 for the boards 42 and 46 on opposite sides of the transformer. The primary windings 52 of the transformer are, of course, connected to board 42 and the secondaries 54 are connected to board 46.

[0037] A conventional three-wave washer 53 is disposed between board 46 and a piezoelectric crystal 56. These transducer assembly components are carried within a dished, externally screw threaded transducer mounting 58. The crystal is bonded circumferentially by an epoxy or the like suitable adhesive to the mouth of the transducer mounting.

[0038] The transducer may be of any one of a number of different kinds and is selected for efficiency in a particular application. Thus, for frequencies above 500 kHz, a piezoelectric crystal in the form of a plane disc is convenient. The crystal converts electrical energy into ultrasonic waves which can radiate directly into the load from the head of the applicator. The crystal may be made from any suitable material such as quartz, barium titanate or lead zirconate-titanate. Lead zirconate-titanate is often preferred over quartz at frequencies below about 15 MHz since it has a low electrical impedance which requires a relatively low driving voltage.

[0039] The material from which the crystal is made and its dimensions, particularly its diameter, will be determined by the intended application. The type and dimensions of the crystal are variable with the frequency and radiant area required. For example, the applicator may be arranged to generate an ultrasonic frequency at 1 MHz over a radiant area of 5 cm² (2 in.²) by equipping the applicator with a crystal of that diameter. The same kind of applicator may be arranged to generate the same signal over a larger radiant area of, say, 10 cm² (4 in.²) by the provision of a crystal of that diameter. Alternatively, the applicator may be arranged to generate an ultrasonic wave of 3 MHz over a radiant area of, for instance, 5 cm² when using a crystal of that diameter in association with an appropriate impedance matching transformer which will be discussed in greater detail below.

[0040] The wave washer 53 is of the conventional commercially available kind comprising a flat, electrically conductive metal annulus which is pressed or stabbed to form three convolutions equispaced about the ring. A wave washer of this type has the characteristic of splaying radially outwardly under axial compression.

[0041] On assembly of the applicator, one convolution is spot soldered to the adjacent circuit board 46. The wave washer can be considered to have inner and outer surfaces, disposed towards the board 46 and towards the crystal 56, respectively. The washer is thus soldered at the point on the inner surface of a selected convolution adjacent the board 46. It is thereby electrically connected to the board 46 at one point only and the remaining convolutions are free from attachment. The free convolutions are thus in the form of wings which, on axial compression, can move radially outwardly, the other convolution being fixed to the board.

[0042] Since the washer is stamped at three equispaced positions to form three convolutions, there are three convoluted areas on the outer surface of the washer relative to the washer attachment. Two convolutions are adjacent the attachment and the other is opposite. These convolutions can be considered to be protrusions relative to the attachment since they are waves or convolutions on the opposite surface of the washer with respect to the point of attachment.

[0043] In the preferred embodiment, the crystal is provided with a conductive electrode on its inner surface. The outer surfaces of the free wave washer convolutions, i.e., the surfaces towards the crystal and which comprise protrusions relative to the attachment, establish electrical contact with the electrode. Electrical energy is supplied to the crystal via this connection to drive the transducer and convert electrical energy to ultrasonic radiation.

[0044] The electrode is not shown on the preferred embodiment illustrated in FIG. 1 as it is extremely thin. The electrode is preferably less than one thousandth of an inch thick. A circular or annular layer of silver material is applied to the surface of the crystal. The electrode layer is then fired or baked permanently on to the crystal.

[0045] The wave washer is sandwiched between the crystal and the circuit board 46. As electrical energy is supplied to drive the crystal, the free protrusions or wings of the washer ideally become airborne with respect to the crystal. They do not physically contact the electrode but are spaced a very small distance, measurable in microns, apart from the crystal electrode. This distance is, however, sufficiently small that the wings and electrode become coupled in capacitance, thereby establishing and maintaining electrical contact.

[0046] As electrical energy drives the transducer, the contact wings of the washer ideally do not come into physical contact with the electrode because the selected frequency of the crystal is in the ultrasonic range of, say, 1 MHz and the natural frequency of the washer is very much smaller, probably significantly below 1 kH. The washer contact wings are thus mechanically spaced apart from the crystal in operation and are substantially unaffected by the mechanical oscillation or vibration of the crystal.

[0047] This spaced apart contact arrangement is a substantial improvement over those arrangements in which the contacts and crystal are in physical contact. Those connected directly to the crystal are subject to mechanical load and stress. In those with spaced contact arms, the arms can move laterally under oscillation. This does not occur with the arrangement of the invention since the aspect ratio of the diameter of the wave washer to its thickness is substantial, its diameter being much greater than its thickness.

[0048] The impedance matching transformer is selected to generate an ultrasonic signal of a predetermined frequency. It may thus either step the driving voltage up or step it down, depending on the crystal employed to generate the desired frequency. Different transformers are associated with different transducers to generate a desired signal. Thus, a 1 MHz signal can be generated from the same type of applicator, one having a radiant area of 5 cm² and the other 10 cm², using different transformers. A 3 MHz signal with a radiant area of 5 cm² can also be generated from the same type of applicator device using an appropriate impedance matching transformer. This is a standard technique which is, for example, used in loudspeaker apparatus.

[0049] The applicator according to the present invention can accordingly be built to radiate an ultrasonic signal of a desired frequency by varying the electrical components as described above.

[0050] The transducer assembly may include suitable spacing members such as generally circular circuit board washers 70 and generally oval mounting screw washers 72. The washers 70 have generally triangular cut-outs 74 in the zone of aperatures 76 in circuit boards 42 and 46. The oval washers also have apertures 78. The leads from the transformer are passed through apertures 76 and 78 on assembly to establish the appropriate electrical connections as described above.

[0051] On assembly, the transformer is sandwiched between the circuit boards with the wave washer fixed outwardly of circuit board 46. The assembly is then positioned behind the crystal which is circumferentially bonded to the mouth of the transducer mounting 58. The exposed leads 38 and 40 of the coaxial cable are connected to the shield cup 34 and the circuit board 42 respectively. A rubber O-ring seal 60 is disposed at the inner end of the screw threading on the mounting 38. The transducer mounting 58 is then screwed into the head of the applicator, at the same time taking up the slack in the coaxial cable.

[0052] The transducer mounting 58 is screwed into the applicator head until a shoulder 80 of the core abuts the inner surface of the shield cup flange. Ground potential is established in the applicator through the core and mounting head 58 in contact with an electrode (not shown) provided circumferentially on the front face of crystal 56. The assembly mounting is arranged to be screwed into the head sufficient for establishing the ground contact between the cup 34 and core 30 and operatively to position the wave washer behind the crystal. When an electrical potential is applied across the crystal, it oscillates in the well known manner to radiate ultrasonic energy.

[0053] When the cable is appropriately taut in the core passage 32, it is secured on the back of the handle 11 by tightening the nut 24 of the cable connector 22.

[0054] It will, however, be appreciated that the applicator may be grounded in any convenient manner. One alternative is shown in Figures 2 and 3. In this embodiment, a crystal as described earlier by Mettler in U. S. Patent 3,025,419 is employed.

[0055] Mettler described an ultrasonic frequency generating crystal assembly. A piezoelectric crystal, in the form of a relatively thin flat disc, is provided with a first coating or plating 90 of conductive material on its one or first surface. The conductive coating may be silver plating. The conductive coating 90 is of smaller diameter than that of the crystal, exposing an unplated margin 92.

[0056] A second conductive coating 94, which is also preferably plated silver, is applied over the entire opposite, or second, surface of the crystal as well as its sides, preferably to the level of the first surface. The conductive coatings are separated by the unplated margin. Although Mettler describes a protective coating for the outside of the plated crystal, this coating has been omitted from this description for convenience of understanding. The protective coating is preferably a glaze such as is used in ceramics and is baked on.

[0057] The crystal is adapted to be set in an applicator mounting head having a mouth dimensioned to receive the crystal. The crystal is bonded at the mouth of the head by means of an electrically conductive cold solder. The cold solder provides an electrical connection between the conductor 94 on the second or outer surface of the crystal and the mounting head.

[0058] The crystal is connected to a suitable energizing circuit by a ground lead connected to the mounting head and a second lead connected to the other conductor 90. A crystal of this kind, appropriately connected, may be used as an alternative form of grounding for an ultrasonic applicator according to the present invention.

[0059] The applicator of the present invention is useful for a variety of purposes. Although it is considered to be especially useful for deep tissue therapy, it is not limited to such use.

[0060] It could, for example, be adapted for surgical use with a metallic head. Ultrasonic generators with metallic heads have recently been developed for cutting bone in surgery.

[0061] It could also be used in the well known ultrasonic techniques used to overcome respiratory and inhalation problems. In these techniques, the generator is immersed in a mixture of a therapeutic substance and water. The ultrasonic radiation from the applicator causes the therapeutic mixture to evaporate in fine particulate form. The micron-size particles can be inhaled more easily and are also taken up into the bloodstream more readily by the lung alveolae. The ultrasonic frequency generating device of this invention is accordingly useful for a variety of purposes.

[0062] The arrangement of the invention provides an electrical connection for an ultrasonic frequency generator which is not affected by mechanical oscillation and which is simple to assemble or install with consistently effective electrical connections.

[0063] Although the invention has been described and illustrated with reference to presently preferred embodiments, it will be apparent to those skilled in the art that many variations and modifications are possible without departing from the scope of the appended claims.

Claims

1. An applicator for generating high frequency energy suitable for use in therapy comprising:
a body for the applicator,
an ultrasonic signal generating transducer electrically connected on the body for converting elec­trical to ultrasonic energy,
electrical connection means for coupling the transducer to a source of electrical power, said connection means having an attachment zone, on a first surface, for connection to the power source and spaced-­apart contact means, on an opposed second surface, for establishing electrical contact with the transducer, said contact means being capable of moving apart with respect to the attachment zone under load to maintain electrical contact during oscillation of the transducer.

2. The applicator of claim 1 in which the contact means includes a plurality of convolutions.

3. The applicator of claim 2 in which the contact means is annular and comprises a wave washer.

4. The applicator of claim 3 in which the wave washer includes three convolutions equispaced about the annulus.

5. The applicator of claim 4 in which the washer is sandwiched between the transducer and a printed circuit board.

6. A transducer assembly comprising:
means for generating predetermined high frequency energy in the ultrasonic range,
transformer means for supplying electrical energy of a selected character to the generator for con­version of said electrical energy to ultrasonic radiant energy, and
electrical connection means including a plurality of convolutions disposed between the transformer and the signal generator, said convolutions defining an electrical attachment point on the side of the connection means towards the transformer and electrical contacts on the side of the connection means towards the generator.

7. The assembly of claim 6 in which the electrical connection means is fixed to a printed circuit board.

8. The transducer assembly of claim 7 in which the transformer means is sandwiched between a pair of printed circuit boards.

9. The assembly of claim 6 in which the signal generator comprises a direct radiating plane disc piezo electric crystal.

10. The assembly of claim 9 including mounting means to carry the generator, said mounting means having a mouth dimensioned to receive the crystal.

11. The assembly of claim 10 in which the mounting means is receivable on an applicator for the therapeutic administration of ultrasound.

12. A therapeutic applicator for radiating an ultrasonic frequency directly into a target body comprising:
a handle having a head including a transducer for converting electrical energy to ultrasonic energy,
an electrode on a surface of the transducer towards the power supply, and
means to connect the transducer to a source of electrical energy, said connection means including an attachment point and a plurality of spaced-apart contacts associated with the electrode, the contacts being adapted to splay apart with respect to the attachment point under dynamic load.

13. The applicator of claim 11 in which the connection means comprises a planar annulus with protrusions on opposed surfaces, the width of the annulus being substantially less than its diameter.

14. The applicator of claim 12 in which the planar annulus is a three wave washer of the conventional kind.

15. The applicator of claim 13 in which the wave washer is sandwiched between the transducer and a printed circuit board.

16. The applicator of claim 14 in which the protrusions on the wave washer are in closely spaced but normally airborne relationship with respect to the transducer, the air gap between the protrusions and the transducer being sufficiently small such that the wave washer and transducer are electrically connected in capacitance to establish and maintain electrical contact in operation.

17. The applicator of claim 11 including a mounting means for the transducer, which mounting means is receivable on the head of the applicator.

18. The applicator of claim 16 in which the mounting means comprises an assembly including a metallic cup for grounding the applicator.

Drawing