Preparing a circuit for the production of shockwaves

• US 5,245,988 A
• Filed: 11/14/1990
• Issued: 09/21/1993
• Est. Priority Date: 11/15/1989
• Status: Expired due to Term

• Current Assignee: Dornier Medizintechnik GmbH Postfach
• Original Assignee: Dormer GmbH
• Inventors: Schultheiss, Reiner, Eizenhoefer, Harald, Einars, Wolfram
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): ZELE, KRISTA MICHELLE
• Application Number:
  US07/614,386
• Time in Patent Office: 1,042 Days
• Field of Search: 181/118, 181/120, 181/142, 315/175, 315/176, 315/171, 372/86, 367/141, 367/147, 128/24 EL
• US Class Current: 601/4
• CPC Class Codes: G10K 15/06 using electric discharge

Abstract

The ignition of spark gaps for the production of shockwaves in the contactless comminution of concrements, using a capacitor discharge is improved by providing at least for some time prior to the ignition proper a voltage much smaller than the breakthrough voltage for producing a small current between the electrodes that prepares a channel in the discharge gap.

Claims

1. In a method of improving shockwave lithotripsy using a liquid-submerged ignition of an arc discharge gap in a lithotripter which includes electrodes submerged in such a liquid for the production of shockwaves to be used in the contactless comminution of concrements, wherein the lithotripter further includes a capacitor, and the method includes a step of selectably connecting the capacitor to the electrodes, thereby causing the capacitor to be discharged across the electrodes for the production of the shockwaves, the improvement comprising;

providing to the electrodes at least for some time prior to the step of connecting the capacitor to the electrodes for the application of a capacitor voltage to the electrodes, a considerably smaller voltage than a breakthrough voltage for the electrodes; and

producing by the said providing step a small, preparatory electric current between the electrodes, the current as so provided being smaller than a current that flows between the electrodes after a full capacitor voltage has been applied to the electrodes, for preparing a channel in the liquid of the arc discharge gap to be effective immediately upon discharge of said capacitor.

2. In a lithotripter, a circuit having a pair of electrodes in a water bath for the production of shockwaves, the circuit further including a capacitor discharge circuit, and a switch means for connecting said capacitor discharge circuit to said electrodes, the improvement comprising,

a low voltage circuit;

and

means for connecting the low voltage circuit to the electrodes prior to closing said switch means and providing a voltage to the electrodes that is significantly smaller than a breakthrough voltage between the electrodes in the water bath, so that a low level, channel-forming electric current flows through the water both between the electrodes.