WO1996003223A1

WO1996003223A1 - Ultrasonic therapeutical treatment apparatus

Info

Publication number: WO1996003223A1
Application number: PCT/FR1994/000917
Authority: WO
Inventors: Guy Dupriez
Original assignee: Guy Dupriez
Priority date: 1994-07-21
Filing date: 1994-07-21
Publication date: 1996-02-08

Abstract

The ultrasonic therapeutical treatment apparatus (1) comprises a first signal generator (6) delivering an alternating or rectified voltage (V1) at a ultrasound frequency; a second signal generator (7) delivering an alternating or rectified voltage (V2) at a sound frequency; and a treatment head (3) intended to be applied against a body region to be treated (5), comprising a piezoelectric transducer supplied by signals produced by the first and second generators. According to the invention, the apparatus is comprised of means (8) for summing the signals from the first and second generators in order to apply the thus combined signals to the transducer, the resonance frequency inherent to the transducer corresponding to the ultrasound frequency produced by the first generator, and the transducer being mounted in the head so as to produce, when the transducer is mounted in the head, a transducer resonance at a frequency corresponding to the sound frequency produced by the second generator, said resonance not being substantially affected by contacting the head with the body region to be treated.

Description

Apparatus for therapeutic ultrasound treatment

The present invention relates to an apparatus for therapeutic therapy by ultrasound. Therapy of the human body by acoustic waves is well known in the field of rheumatology, sports medicine, rehabilitation, etc.

DE-C-928 379 and US-A-4 530 360 describe, among other documents, known examples of devices making it possible to carry out such therapeutic treatments.

These devices include an ultrasonic frequency signal generator supplying a piezoelectric transducer transforming electrical energy into mechanical vibrations; the transducer is mounted inside a head which is coupled to the region to be treated, either by contact (using a gel or an oil allowing the transmission of ultrasound), or in water by emission of vibrations a short distance from the area to be treated.

These devices operate either in continuous emission of ultrasound, or in pulsed emission to avoid heating of the treated tissue. while having maximum instantaneous power. In this latter case, as described for example in the aforementioned prior art, a signal generator (for example of pulses) with sound frequency modulates the signal produced by the generator with ultrasonic frequency.

In this regard, here and throughout the rest of the description, the term “ultrasonic frequency” will be understood to mean a frequency greater than a few hundred kilohertz, typically between 800 kHz and 3 MHz, a frequency of 1 MHz being a commonly used value. used in practice in the prior art. Ultrasonic frequency acoustic waves (vibrations of air, water or any other material medium) have the following well-known properties compared to lower frequency waves such as sound frequency waves - which are of elsewhere all the more marked as the frequency is high: rectilinear propagation, high density of radiated energy and significant absorption by the propagation medium.

Similarly, the term "sound frequency" will be understood to mean a frequency of the spectrum covering both the range of audible sounds (of the order of 40 Hz to 12 kHz) and the frequencies below this range (infrasound) and above , the frequency possibly going up to a few hundred kilohertz in the latter case.

In addition to ultrasound therapy devices, low frequency vibration therapy devices are also known, as is described for example in DE-A-37 15 269, where an oscillating electrical signal generator at a frequency of 60 to 400 Hz supplies an electromechanical transducer such as an electromagnet coming to drive a counterweight applied against the region to be treated.

Medical practice shows that the two modes of therapeutic treatment, by ultrasonic vibrations and low frequency vibrations, each have advantageous but different therapeutic effects.

The author of the present invention has however found that these different therapeutic effects could be complementary to one another, and that it could be desirable to apply the two treatments simultaneously in order to combine the respective advantages. One of the aims of the present invention is therefore to propose an apparatus making it possible to produce, with a single treatment head, both vibrations at ultrasonic frequency and vibrations at sound frequency, in order to combine the effects thereof. therapeutic. According to a first aspect of the invention, an ultrasonic frequency signal and a sound frequency signal are produced separately, and these signals are added to apply them jointly to the same transducer.

It will be noted that, in order to be able to combine the effects of the two types of vibration, it is necessary to add the amplitudes of the signals, thus in principle serving a substantially constant average power applied, unlike modulated signal ultrasonic treatment where the average power of the applied vibration varies with the rate of modulation and therefore does not provide the advantages of treatment with a vibration at sound frequency. Indeed, in these known devices, the sound frequency is a simple modulation frequency, which defines the envelope of the ultrasonic signal but does not deliver any mechanical energy to the sound frequency. It is however possible to provide, without departing from the scope of the present invention, a signal whose ultrasonic component already comprises a modulation, this modu¬ lation coming in addition to the addition of the signal at sound frequency, an addition which is essential for the 'obtaining advantageous effects of the invention, which would not be obtained by simple modulation. According to another aspect of the invention, to allow the simultaneous production of two vibrations, both sound and ultrasound, by a single head and a single transducer, a mechanical structure of the treatment head is proposed which, in addition to the proper resonance at ultrasonic frequency of the piezoelectric transducer, to obtain resonance at sound frequency and therefore the effective production of mechanical vibrations capable of being transmitted to the body region to be treated.

More specifically, the therapeutic treatment apparatus of the invention, which is of a type similar to that described in DE-C-928 379 and US-A-4,530,360 mentioned above, that is to say a therapeutic ultrasound treatment apparatus comprising: a first generation signal erector, delivering an alternating or rectified voltage at ultrasonic frequency; a second signal generator, delivering an alternating or rectified voltage at sound frequency; and a treatment head, intended to be applied against a body region to be treated, comprising a piezoelectric transducer supplied by the signals produced by the first and second generators.

According to the invention, this apparatus is characterized in that: it comprises means for adding the signals of the first and second generators to apply the signals thus combined to the transducer; the natural frequency of resonance of the transducer corresponds to the ultrasonic frequency produced by the first generator; and the transducer is mounted in the head so as to cause, when the latter is mounted in the head, a resonance of the transducer at a frequency corresponding to the sound frequency produced by the second generator, this resonance not being substantially affected by the contact of the head with the body region to be treated.

In a particularly advantageous embodiment, the transducer is mounted in the head on the internal face of a bottom wall thereof, the external face of this wall being intended to come into contact with the body region to be treated, the the internal face of this wall being uniform and the transducer resting on the latter over most or all of its extent and with the interposition of a homogeneous mass of intermediate material.

According to a certain number of preferred characteristics: in the radial direction, the extent of the mass of intermediate material is greater than that of the transducer; the connection of the transducer to its connection wires is a galvanic connection, in particular a welded connection, produced between each of the faces of the transducer and a respective connection wire; the face of the transducer opposite the bottom wall carries a mass of weld filler metal extending, in the radial direction, over most or all of the extent of the transducer; the face of the transducer facing the internal face of the bottom wall carries a weld embedded in the homogeneous mass of aforementioned intermediate material. 0 Other characteristics and advantages will appear on reading the detailed description below of an exemplary embodiment of the invention, made with reference to the accompanying drawings.

Figure 1 is a block diagram of the apparatus of the invention, with its electronic circuits and its processing head.

FIG. 2 illustrates a variant implementation of the circuits of FIG. 1.

Figure 3 is a vertical section of the processing head of the apparatus according to the invention. FIG. 4 shows the shape of the signal produced by the electronic circuit of the apparatus and applied to the processing head of FIG. 3.

0

Schematically shown in Figure 1 the apparatus 1 according to the invention, which comprises an electronic unit 2 connected to an electro-acoustic transducer 3 via a connecting conductor 4. This transducer is applied to a region body to be treated 5, either directly with a gel or contact oil, or at a short distance (a few centimeters) in an environment that is good conductor of acoustic waves such as water.

The electronic unit 2 contains a first signal generator 6 delivering a voltage V _j with an ultrasonic frequency, preferably a frequency of the order of 2 MHz (this particular frequency being preferably chosen from the usual frequency of 1 MHz used in prior art ultrasonic treatment devices). The signal V _l is for example a square signal. To allow fine tuning of the signal produced on the resonance frequency of the piezoelectric element of the transducer 3, the frequency of the generator 6 is preferably adjustable.

A second generator 7 produces a signal V ₂ at sound frequency, for example of the order of 50 to 100 Hz. This sound frequency can be fixed, adjustable or variable over time. In a particular example, these may, as illustrated in FIG. 4, be rectangular pulses 1 ms in width with a recurrence frequency of 200 Hz. It is also possible to choose for this sound frequency one of the specific frequencies (two or three, located in the range 5 kHz - 10 kHz and determinable by experimentation), which produce in loud free space a loud audible sound which is stopped by contact with the skin; this phenomenon makes it very easy to check the correct coupling of the head with the body region to be treated.

Of course, the various frequency values given above have no limiting character and depend essentially on the characteristics of the transducer of the apparatus, as well as on the desired therapeutic effects. The generator 6 can thus produce any frequency in the ultrasonic field, likewise for the generator 7 which can produce any frequency in the sound range, the values given here being only indicative.

The two signals V _j and V ₂ are combined in an adder stage 8, the output of which is applied to the input of an amplifier stage 9 controlling the transducer 3 either directly or via a pulse transformer.

The signal received by this transducer has the form illustrated for example in FIG. 4, namely a non-modulated and alternating signal (that is to say comprising positive and negative alternations). But it could also be a signal whose ultrasonic component includes a modulation (this modulation coming in addition to the addition of the signal at sound frequency, an addition which is essential for obtaining the advantageous effects of the invention, which would not be obtained by a simple modulation) and / or of a rectified signal, comprising only positive or negative alternations, that is to say for example comprising a continuous offset with respect to the figure signal 4.

In the example illustrated in FIG. 4, the voltage component at ultrasonic frequency V _χ is of the order of 20 V at no load and 200 V at tuning, that is to say when the head is connected 3 at the output of the amplifier 9. The piezoelectric transducer of this head resonating at the same frequency as the applied signal and the transducers of this type having a high overvoltage factor, the output voltage of the amplifier increases in significant proportions when the transducer is coupled to the electronic circuit. For the same reason, the rectangular vacuum shape of the signal V. will transform into a shape close to a sinusoid due to the filtering effect introduced by the piezoelectric component in resonance. Still in this example, the voltage component at sound frequency V ₂ observed at the terminals of the transducer has an amplitude of the order of 9 V, with pulses of recurrence period T ^ = 5 ms and duration T ₂ = 1 ms.

The various circuits making up the electronic unit 2 are in themselves known circuits and will not be described in more detail. It can simply be noted that one can provide, as a variant, instead of the separate additional stage 9, an ultrasonic frequency generator 6 directly comprising a signal addition input to which the signal V ₂ produced by the generator is applied 7 at sound frequency. This simplifies the overall diagram of the electronic circuit of the apparatus, all other things being equal. We will now describe, with reference to FIG. 3, the structure of the treatment head 3 making it possible to jointly produce the sound and ultrasonic vibrations.

This head 3 comprises a piezoelectric transducer 10 in the form of a ceramic or quartz blade making it possible to transform the mechanical signals produced by the electronic unit and transmitted by the conductor 4 into mechanical vibrations.

This transducer 10 is enclosed in a housing 11, for example of cylindrical shape made of thin sheet 0.5 mm thick with a diameter of 25 mm and a cylinder height of 40 to 50 mm. These dimensions (which are only orders of magnitude, purely indicative) allow¬ have an extremely light head, a few tens of grams, which can be held at fingertips by the practitioner, opposite the heads treatment of the apparatuses of the prior art which, apart from the fact that they produced only ultrasonic vibrations, often weighed several hundred grams and most of the time required the use of a handle.

As regards the piezoelectric plate, it is possible to use a ceramic 10 mm in diameter and 2 mm thick resonating at a typical frequency of the order of 2 MHz. The cylinder 11 of the treatment head is a blind cylinder closed by a flat bottom 12 in the lower part and open in the upper part. The external face 13 of the bottom wall 12 is intended to be applied against the body region to be treated, while the internal face 14 of this same wall carries the piezoelectric transducer 10. Typically of the invention, this internal face 14 is uniform and the piezoelectric strip 10 is bonded to the latter over the entire extent of its face 15 vis-à-vis by means of a resin mass 16, for example an epoxy resin. Note that this structure differs significantly from that of the transducers for ultrasound treatment equipment in which the piezoelectric plate rests on radial ribs projecting from the bottom wall, therefore on a very small part of its surface - which prevents vibration in the sound field.

Very advantageously, the mass of resin 16 extends over a diameter notably greater than that of the transducer 10, for example of the order of 15 to 20 mm, and over a significant thickness, for example of the order of 0 , 5 to 1 mm (it will be noted that, in the prior art, this thickness was always necessarily very small, of the order of 0.1 mm at most, to allow a capacitive coupling between the internal face of the transducer and the case metallic).

This high mass of resin has the effect of improving, in very large proportions, the resonance of the blade-housing assembly in the sound domain, with in addition a weak damping of this resonance when the head is brought into contact with the body region. 5 to be processed.

Also characteristic of the invention, the piezoelectric blade is connected to the conductor of the connection cable 4 by a galvanic connection, advantageously a welded connection: the lower face 15 of the piezoelectric blade is welded to the wire 17 by a solder (of the silver-tin solder type or the like) 18, while the upper face 19 is soldered to the conductor 20 by a solder 21.

This structure is again opposed to the conventional connection modes of the heads of the prior art, in which the connection to the underside was generally a capacitive connection with the body of the housing (implying, as has been said above, a very thin thick- glue between the piezoelectric plate and the housing), while the connection to the upper face was generally a connection by spring, with all the corresponding drawbacks.

In the case of the invention, the welded connection provides maximum reliability and also makes it possible to galvanically isolate the metal housing from the head with the supply wires of the transducer (the lower weld 18 being entirely embedded in the mass of resin 16).

In addition and above all, the additional mass constituted by the hard sou¬ 21, which is deliberately given a large volume, makes it possible to further improve the resonance of the blade-housing system in the sound domain. The mass of metal of the weld 21 can thus advantageously have a thickness of up to 4 to 5 mm.

All the elements located in the bottom of the housing 11 are embedded in a polyethylene foam 22, acoustically neutral and electrically insulating, and the opening of the cylinder is closed by a closing resin 23 which can be for example an epoxy resin.

The coupling of the housing body and the blade 10 - which, alone, could not vibrate in the sound domain - with the interposition of a large mass (relative to the mass of the transducer alone) of resin 16 and, superabundantly , the presence of the mass of metal of the weld 21 makes it possible to produce a vibration in the sound domain of the bottom wall 12 and therefore to apply, in addition to the ultrasonic energy, mechanical energy of therapeutically effective level at frequency sound to the area to be treated.

This sound vibration is in fact clearly audible at more than 10 cm from the ear, due to the strong resonance of the head in the sound field, so that the practitioner can easily realize the proper functioning of the 'apparatus, unlike for example modulated ultrasound treatment apparatus, which produced only a very low perceptible vibration.

SUBSTITUTE SHEET (RULE 2β)

Claims

1. An apparatus (1) for therapeutic treatment by ultrasound, of the type comprising: - a first signal generator (6), delivering an alternating or rectified voltage (V _j ) at ultrasonic frequency,

a second signal generator (7), delivering an alternating or rectified voltage (V ₂ ) at sound frequency, and

a treatment head (3), intended to be applied against a body region to be treated (5), comprising a piezoelectric transducer (10) supplied by the signals produced by the first and second generators, apparatus characterized in that:

- it comprises means (8) for adding the signals of the first and second generators to apply the signals thus combined to the transducer,

the natural resonant frequency of the transducer corresponds to the ultrasonic frequency produced by the first generator, and

- The transducer is mounted in the head so as to cause, when the latter is mounted in the head, a resonance of the transducer at a frequency corresponding to the sound frequency produced by the second generator, this resonance not being substantial ¬ affected by bringing the head into contact with the body region to be treated.

2. The apparatus of claim 1 wherein the transducer (10) is mounted in the head on the inner face (14) of a bottom wall (12) thereof, the outer face (13) of this wall being intended to come into contact with the body region to be treated, the internal face of this wall being uniform and the transducer resting on the latter over most or all of its extent and with the interposition of a homogeneous mass of interlayer material (16).

3. The apparatus of claim 2 wherein, in the radial direction, the extent of the mass of interlayer material is greater than that of the transducer.

4. The apparatus of claim 1 wherein the connection of the transducer to its connection son is a galvanic connection.

5. The apparatus of claim 4 wherein the galvanic connection is a welded connection, formed between each of the faces (15, 19) of the transducer and a connection wire (17, 20) respective.

6. The apparatus of claim 5 in which the face (19) of the transducer opposite to the bottom wall carries a mass of welding ap¬ metal (21) extending, in radial direction, on the major part or all of the extent of the transducer.

7. The apparatus of claims 2 and 5 taken in combination in which the face (15) of the transducer facing the internal face of the bottom wall carries a weld (18) embedded in the homogeneous mass of material interlayer (16).