JPH06505648A - Method and device for interposing liquid between electrodes of shock wave device - Google Patents

Abstract

A method and a device for producing an electric discharge between two electrodes are described. The method is characterized in that the electric arc resistance is substantially reduced at least between the electrodes to a resistance value which is close to or even lower than the critical resistance. This is achieved by placing between the electrodes an electrically conductive liquid medium (32) held in a substantially sealed container (30) surrounding the electrodes, whereby the electrical discharge rate between two electrodes can be improved while completely or substantially completely eliminating the latency time.

Description

[Detailed description of the invention] A method and device for interposing a liquid between electrodes of a shock wave device. A method and apparatus for interposing a conductive liquid in a conductive liquid and using such a method and apparatus The present invention relates to a shock wave generator.

U.S. Patent No. 2.559.227 by RIEBER High frequency shock wave generators are known. This device is a truncated oval reflector. In this reflector 80, the ellipsoids converge to each other at the first focal point of the ellipsoid. A shock wave is generated by a discharge or arc between two electrodes arranged in the same manner. child The purpose of the device is to locate the second focal point of the ellipsoid outside the truncated reflector 80. (Figure 3 and column 7, line 51 to column 9, line 30) (see up to line).

Electrodes 12 and 13 are made of a highly conductive material such as copper or brass, and an insulator 2 6. This insulator 26 can be pivoted by the device 11a111b (42-5 in column 4). (See line 3, column 8, lines 40-47).

In this Lieber device or similar devices, the high-voltage switch is closed. , the capacitor 11 is instantaneously discharged, and a discharge or arc occurs between the electrodes. (According to the device of the second b2b1 degree leaver, the circuit between the electrodes is equipped with a capacitor. Furthermore, it has self-inductance. In such a circuit, the capacitor It can be seen that the sa discharge is of the damped oscillation type. In other words, the capacitor discharges After that, the voltage lower than the very high initial voltage (15,000~20,000V) The capacitor is discharged and recharged in the reverse direction, followed by forward recharging. Repeat until the charge contained in is exhausted.

At the same time, an arc is generated between the two electrodes. As a result, the current in the two electrodes also As can be seen with reference to Figures 1a, 1b and 1c, it is of a damped vibration type.

Figure 1a shows the voltage change over time, while Figure 1b shows the Lieber-type discharge circuit. It shows the change in current in the path. The circuit is time 1. When closed, the electrode terminal It can be seen that the voltage instantly rises to the voltage value across the capacitor (first (See figure a). First, the liquid in which the electrode is immersed (usually water) is always slightly conductive. The second is the capacitor that powers the electrode for safety and arc ignition. Since a high resistance is connected to the column, a small current flows between the two electrodes (the Figure 1b).

After a time t2, which is called the incubation period or delay time, there is a gap between the electrodes. An arc occurs. At this moment, as clearly shown in Figure 1b, the current flows instantaneously. Increases several KA. The arc has extremely low resistance (approximately 1/100 or 1/100 It is a well-known fact that the RL type circuit Oscillations of current (Fig. 1b) and voltage (Fig. 1a) during discharge of a capacitor at is important because of its low resistance value.

The energy contained in and released from the arc is absorbed by the liquid in which the electrodes are immersed. vapor (usually water), creating vapor bubbles and a resulting shock wave. This The faster the energy is released, the more efficient the shock wave is.

In this way, due to the oscillating characteristics of the current, the external medium The supply of energy to is incremental, as clearly shown in FIG. 1c.

This means that the faster a liquid, especially water, evaporates, the stronger the pressure wave becomes. Indicates whether the rise time is short.

Therefore, in order to evaporate a large amount of liquid, especially water, a large amount of energy must be transferred instantaneously. must be obtained.

However, most of the currently known devices are It uses a damped oscillatory discharge to gradually release energy over time. (Figure 1c).

In European Patent No. 0.296.912, the applicant describes Instantly or A first solution was proposed for release in a relatively short time. to produce this effect , a high resistance insulating element (32) is interposed between the arc generating electrodes 12.14. proposed to increase the electrical resistance at least on the arc path between the electrodes. . This solution is completely satisfactory if the initial pressure wave generates a shock wave that is approximately spherical. It's something you can go to.

However, the above solutions are limited by the small dimensions of the electrodes and the mechanical strength against shock waves. Therefore, it is difficult to realize it mechanically. Moreover, the main feature of this special solution is The purpose is only to improve the discharge conditions when an electric arc occurs, and to The problem between them is not resolved. Therefore, this method reduces the reproducibility of the discharge and therefore the impact Wave reproducibility is not improved.

Therefore, the main object of the present invention is to reduce the delay normally required to generate a discharge between the electrodes. Discharge circuit between two electrodes by completely or almost completely eliminating the time Most of the energy stored as electric charge in the capacitor is transferred instantaneously in a relatively short period of time. solve new technical problems by providing solutions that enable There is a particular thing.

Another object of the present invention is to completely eliminate the delay time when generating a discharge between electrodes. 11 completely removed, greatly improving the localization of discharge generation and improving the reproducibility of shock waves. solve new technical problems and provide solutions that enable significant improvements in It's about solving.

Furthermore, another object of the present invention is to complete a delay time when generating a discharge between electrodes. completely or almost completely removes the charge on the capacitor of the discharge circuit between the two electrodes. releasing most of the stored energy instantly or in a relatively short period of time We provide a solution to generate critically damped discharges that enable It's about solving problems.

A further object of the present invention is to solve the above-mentioned new technical problems and to To provide a method to reduce wear and limit the degree of alternation that occurs in existing equipment. be.

The invention furthermore can be used on an industrial scale, particularly with respect to ex-vivo lithotripsy. It is possible to solve the above new technical problems in a very simple way.

All of the above-mentioned new technical problems can be solved in a satisfactory manner for the first time with the present invention. has been solved at a low cost and at an industrial level, especially for ex-vivo lithotripsy. Ta.

In other words, according to the first feature of the present invention, there is a gap between at least two discharge electrodes. In a method for improving the conditions of electrical discharges that occur in liquid media such as water, A conductive liquid medium placed in a substantially closed reservoir surrounding at least between the electrodes The resistance of the discharge path is considerably reduced at least between the electrodes by interposing the The present invention provides a method characterized by reducing the field resistance to a value close to the field resistance.

The above reservoir is manufactured from a material that has little effect on shock wave propagation. Ru. Examples of such materials are latex, silicone or metal strips etc. are known to those skilled in the art.

According to another advantageous embodiment, the electrode supports the reservoir and is removable. It has become. Therefore, the electrodes can be supplied together with the reservoir and the assembly can be used It is usable, disposable, and has lower maintenance costs than traditional solutions.

In a particularly advantageous embodiment, the electrically conductive liquid medium used is a conventional one used as a reference. At least 1/10, preferably at least 1/10 of the electrical resistance value of ionized water It has an electrical resistance of 0 or less.

More preferably, the electrical resistance of the electrically conductive medium of the present invention, expressed in resistivity, is about It should be less than 15Ω. The conductive liquid medium consists of an aqueous or non-aqueous electrolyte be able to. Suitable aqueous electrolytes include ionic compounds, especially halogenated salts. salts such as sodium chloride, ammonium chloride, or alkali metal or containing sulfates or nitrates of alkaline earth metals or transition metals such as copper. There is water to have. Conductive and electrically conductive aqueous liquid media that are commonly used today are loog/l or or water containing salt at a concentration of 200 g/l and having a resistivity of 10 and 5 Ω, respectively. be.

A more preferred conductive aqueous liquid medium includes 10% by weight sodium chloride (approximately 100 g/l) and 0.5-2% by weight of phosphate, especially disodium phosphate (Na , HPO2・12H20). The resistivity of this conducting medium is approximately 8Ω.

Preferably, a dye such as methylene blue is added at a rate of 2 mg/l and Be sure to check for leaks.

Suitable non-aqueous conductive media include conductive particles such as metal particles added to the conductive medium. Mention may be made of electrically conductive oils which are known to those skilled in the art.

According to a second feature, the invention provides at least two This is a device that improves the condition of the discharge that occurs between the electrodes that perform the discharge. Both reduce the resistance of the discharge path between the electrodes and bring it down to a value close to the critical resistance. means, the means surrounding the electrode and being filled with an electrically conductive liquid medium. A device is provided, characterized in that it has a closed reservoir. of the above reservoir The material is selected so that it does not substantially affect the propagation of shock waves. Especially the above The reservoir can be made of latex, silicone or metal strip . It can be in the form of a membrane surrounding the electrode.

According to a third characteristic, the invention further provides a method for immersion in a liquid discharge medium, in particular of the in vitro type. A device that generates a shock wave by a discharge between at least two immersed electrodes, the device comprising: It also relates to a device characterized by being equipped with means for improving the discharge state as described above. It is. According to a preferred embodiment, the device comprises a truncated oval reflector; At the internal focus of this reflector, a shock wave is generated by a discharge between at least two electrodes. Then, a shock wave gathers at that external focus. The above truncated oval reflector is a liquid cup. filled with medium. In this case, the electrodes are therefore essentially above surrounding the internal focus. A conductive liquid medium is provided in the reservoir. The reservoir is filled with another liquid medium, in particular water, in a truncated oval shape. Used inside the flexor.

Other properties of the conductive medium of the present invention have already been mentioned with respect to the method and are applicable to the present apparatus. It is clearly applicable.

According to the invention, the discharge takes place in a conductive medium, so that the delay time is completely or completely is almost completely removed. Furthermore, the shock wave generated between the electrodes has very good reproducibility. Become something. This means that in the conventional case, the arc is random both in time and space. In the present invention, this is not the case. This is due to the fact that this is not the case. Furthermore, the present invention eliminates the oscillating current. , the discharge is of the critically damped type. This is further explained below with reference to the attached drawings. It will be easily understood.

Furthermore, the present invention uses a reservoir filled with a conductive liquid. The amount of electrically conductive liquid is very small and the patient does not come into contact with this liquid. difference Furthermore, there is less electrical danger because the discharge occurs in a closed system.

Therefore, the present invention covers various techniques described above that were unexpected and not obvious to anyone skilled in the art. It realizes the following advantages.

Other objects, features and advantages of the present invention will be found in the following description with reference to the accompanying drawings. will be clearer to those skilled in the art. The figures particularly show preferred embodiments of the invention; These are merely examples and do not limit the invention. In the figure, Figure 1a, lb and lc are Lieber type discharge circuits of U.S. Patent No. 2.559.227, respectively. The voltage obtained in a normal arc discharge generated between two electrodes using Shows current and energy curves.

FIG. 2 shows a substantially closed reservoir filled with a conductive liquid medium, Especially from outside the body, it is equipped with the discharge means of the present invention such that a discharge occurs between two electrodes. FIG. 2 is a schematic partial cross-sectional view of a shock wave generator for performing lithotripsy.

3a, 3b, 3c each have at least two parts according to the invention as shown in FIG. Voltage, current and energy obtained using a conductive liquid medium interposed between the electrodes of FIG. 2 is a diagram substantially similar to FIGS. 1a, 1b, IC, showing the curves of FIG.

FIG. 2 shows the IJ-bar of U.S. Pat. Shock wave used in extracorporeal lithotripsy, etc. with a truncated oval reflector of the type It is a schematic diagram of the generator. This reflector 10 has two discharge electrodes 12. 14 are installed facing each other, here German published patent no. 2.635. A cage-like structure is known from 635 patent. these two The discharge electrodes 12 and 14 are arranged in such a way that they converge on each other at an internal focus indicated by the reference number F. It's becoming a sea urchin.

The second focal point of the ellipse is located outside the truncated elliptical reflector 10 and As detailed in the U.S. Pat. match. Electrode 12 is grounded and further connected to a capacitor, as depicted in FIG. It is connected to one end of C. Another electrode 14 is for opening and closing a gas-filled arc-extinguishing circuit breaker, etc. It is connected to capacitor C via device (2). This switchgear has reference number 20. It is intermittently shut off by the control device shown.

A high value resistor R is placed in parallel with the capacitor C. For capacitor C, e.g. For example, as shown in Figure 1 of the applicant's European Patent No. 0.296.912. A high voltage of 10.000 to 20.0 OOV is charged from the power supply, but this circuit is Not shown here.

According to the prior art, the elliptical reflector 10 is filled with a shock wave transmitting liquid, typically water. The resistance of this liquid to electric current is not small. regular ionized water The electrical resistance value is approximately 1500Ω in terms of resistivity. Lieber U.S. Patent No. 2.55 In the case of highly insulating oils, as in the case of No. 9.227, the resistivity is approximately 3 to 3. It is a 5MΩ country.

In prior art circuits where the liquid medium between electrodes 12.14 is ordinary ionized water. When discharging, the discharge characteristics are as shown in Figures 1a, 1b and 1c. There is a considerable delay time, and the discharge state is an oscillating type, in which energy is transferred to an external medium. Communicate step by step.

According to the invention, an essentially closed reservoir 30 is used and a channel is introduced into this reservoir. The electric liquid 32 is filled to bring the resistance to the discharge path between the electrodes 12 and 14 close to the critical resistance. It can be lowered up to 100%, preferably lower than that. This method A book that proposes to significantly increase the electrical resistance between electrodes by interposing an insulating element in Those recommended in European patent 'JG O, 296,912 by the applicant The law is the opposite.

Around this reservoir 30 itself, a liquid coupling medium 34 is arranged in a truncated oval shape. It satisfies Rector 10. This medium is especially water, so that the patient's skin remains normal. It will come into contact with normal water.

This reservoir has little influence on the shock waves generated by the discharge between the electrodes 12.14. Manufactured using materials that do not cause noise. Such materials are known to those skilled in the art. be. Particular examples include latex, silicone, and metal strips.

A practical embodiment is in the form of a membrane fixed in a suitable manner, e.g. As can be seen, it is fixed to an electrically conductive external element 12a that supports the electrodes.

Preferably, the electrode is configured to support the reservoir and is configured to support the reservoir as shown in FIG. and is removable. Therefore, the electrodes can be supplied together with the reservoir. The electrode and reservoir assembly is usable, disposable, and compatible with traditional solutions. Maintenance costs are lower than the fixed method.

In a preferred embodiment of the invention, the conductive liquid medium 23 contained in the reservoir 30 is Electrical resistance is the resistance of normal ionized water used as a reference (expressed as resistivity) 1.500ΩCa+) at least 1/10, more preferably at least 1 /100. The electrical resistance of the conductive medium of the present invention is approximately 15Ω1 in terms of resistivity. It is preferable that it is less than

Any aqueous or non-aqueous conductive liquid can be used as the conductive liquid medium of the present invention. be able to. Suitable aqueous conductive liquids include ionizable compounds that are soluble in pure water. , especially adding salts such as noherogenated salts, especially hydrochlorides, sulfates, nitrates. It is an aqueous electrolyte. Particularly preferred aqueous electrolytes are sodium chloride or ammonium chloride. This is water with added sodium. A more preferred medium is 100 or 2QOg/l salt The resistivity is 10Ωcai6 and 5c, respectively.

More preferably, 10% by weight of sodium chloride and 0.5 to 2% by weight of diphosphoric acid. Contains sodium (Na2HP　O=・12H,O) and has a resistivity at a temperature of 25℃ An aqueous conductive medium with a resistance of about 8 ohms is used.

(chloride) The ratio of IJium and phosphate is not a decisive factor, and the resistivity value is 1 It can be adjusted up to the 0Ω mark. Maintain at least 0.05% phosphate by weight It is preferable to Adding dye to the conductive medium to detect leaks in the reservoir 30 It is also possible to leave it as

Suitable non-aqueous conductive media include conductive particles such as metal particles added to the conductive medium. Examples include conductive oils that have been given electrical properties.

According to the present invention, when using a conductive liquid medium, as shown in FIGS. 3a, 3b and 3c, Such discharge characteristics can be obtained. Time 1. When the electrode is charged with A problem occurs. Furthermore, the discharge is of the critical damping type and is no longer of the oscillating type. Ma The energy generated by the Sent to the external medium in a short time.

As a result, arcs do not occur randomly in time or space, but on the contrary , due to the fact that it forms a perfectly localized vapor bubble to occur at time t1. Therefore, the reproducibility of shock waves is greatly improved. The time change shown in FIG. and 14 as a conductive medium with a concentration of 200 g/J and a capacity of 100 g/J. capacitor of nF, inter-electrode spacing of 0.411n, and overall internal self-inductance This was obtained using the discharge circuit shown in FIG. 2 with a resistance L of 80 nH.

In this specification and claims, the critical resistance is expressed by the formula: % formula %) (However, L is the value of the internal self-inductance of the discharge circuit of capacitor C, C is the resistance value between the electrodes that substantially satisfies the capacitance value of the capacitor.

According to the invention, excellent shock wave reproducibility is obtained using a conductive liquid medium. Special When using salt water, the average deviation is 5% or less. In contrast, normal io When using chlorinated water, the average deviation is about 30%. Therefore, the present invention first provides bring about the unanticipated technical advantages mentioned and, as a result, solve the problems mentioned above. Solve everything. The invention also provides the possibility of implementing the method described above.

Finally, the present invention generates a shock wave by creating an arc between two electrodes. A device which uses the methods or means for improving the discharge conditions already described. It also includes devices characterized by: In particular, this shock wave generator was previously described a truncated oval reflector with a conductive liquid medium or server as in Having another liquid coupling medium surrounding the reservoir and filling the reflector It is characterized by. A particularly applicable example is extracorporeal lithotripsy.

Submission of translation of written amendment (Article 184-8 of the Patent Law) June 28, 1993 -

Claims (14)

[Claims] 1. an electrical discharge that occurs in a liquid medium such as water between at least two discharging electrodes In a method that particularly improves the reproducibility of the conditions of A conductive liquid medium contained in a reservoir (30) is interposed between at least the electrodes, and a small At the very least, the resistance to the discharge path between the electrodes has been significantly reduced to near critical resistance. A method characterized by lowering the value to a value. 2. The resistance of the above conductive liquid medium is the resistance of normal ionized water used as a reference. as claimed in claim 1, which is at least 1/10, preferably at least 1/100 of the value. How to put it on. 3. The electrical resistance of the conductive liquid medium is less than about 15 Ωcm in terms of resistance coefficient. The method according to claim 2. 4. Claims in which the conductive liquid medium consists of an aqueous or non-aqueous electrolyte, preferably salt water The method according to any one of Items 1 to 3. 5. occurs in a liquid medium such as water between at least two electrically discharged electrodes In a device that specifically improves the discharge condition, at least the discharge path between the electrodes is improved. There is a means to significantly reduce the resistance to a value close to the critical resistance, and the means is , an essentially closed reservoir surrounding the electrode and filled with a conductive liquid medium (32). An apparatus characterized in that it comprises a bar (30). 6. An electrode supports the reservoir (30) and is removable so that its 6. The device of claim 5, wherein the assembly is usable and disposable. 7. The above conductive liquid medium has a lower resistance value than ordinary ionized water used as a reference. Resistance measured in resistivity of at least 1/10, preferably at least 1/100 7. A device according to claim 5 or 6, having a value of . 8. 8. The conductive liquid medium according to claim 7, wherein the conductive liquid medium comprises an aqueous or non-aqueous electrolyte. Device. 9. The above-mentioned conductive liquid medium contains pure water and ionizable compounds, especially halogenated salts, sulfur Claim 7, characterized in that it is composed of a substance to which an acid salt or a nitrate is added. or 8. 10. The resistance value expressed as the resistivity of the conductive liquid medium is less than about 15 Ωcm. , that this medium is, for example, salt water with a concentration of 100 g/l or 200 g/l. 10. A device according to any one of claims 7 to 9. 11. The conductive liquid medium (32) comprises about 10% by weight of sodium chloride and 0.5% by weight of sodium chloride. Aqueous obtained by adding ~2% by weight of sulfate, especially disodium sulfate, to pure water The device according to any one of claims 7 to 10, characterized in that it consists of an electrolyte. 12. Generating an electric arc between two electrodes, especially the type used in vitro A shock wave generating device, comprising the device according to any one of claims 5 to 11. or using the method according to any one of claims 1 to 4. device to do. 13. A reservoir (30) filled with a conductive liquid (32) as defined above. a truncated oval reflector (10) with a truncated oval reflector (10), further surrounding said reservoir (30); and another liquid coupling medium which fills the reflector (10) and said electrically conductive A claim characterized in that the liquid (30) is as defined in any one of claims 7 to 11. 13. The shock wave generator according to claim 12. 14. The shock wave generating device according to claim 12 or 13, which is an in vitro lithotripsy device. Place.