Adjustable electrode and related method

• US 6,217,531 B1
• Filed: 10/26/1998
• Issued: 04/17/2001
• Est. Priority Date: 10/24/1997
• Status: Expired due to Term

• Current Assignee: MTS Medical Technologies & Services GmbH
• Original Assignee: Its Medical Technologies & Services GmbH
• Inventors: Reitmajer, Ralph
• Primary Examiner(s): Lateef, Marvin M.
• Assistant Examiner(s): SHAW, SHAWNA JEANNINE
• Application Number:
  US09/178,625
• Time in Patent Office: 904 Days
• Field of Search: 601/2-4, 600/439, 367/146, 367/147
• US Class Current: 601/4
• CPC Class Codes: G10K 15/06 using electric discharge

Abstract

The present invention relates to a electrode assembly and related method that includes a insulator assembly, an electrode assembly, a charging system, a mechanism for measuring electrical voltages, a mechanism for adjusting the distance between inner and outer electrode tips, and a controller. The insulator assembly includes an insulator body having a hollow central portion with a threaded inner wall. The insulator assembly includes inner and outer conductors that are electrically connected to the charging system and are physically connected to inner and outer electrodes, respectively. The electrodes are positioned such that their longitudinal axes are aligned and the tips of the electrodes are in relatively close physical proximity. The distance between the tips is defined as the spark gap. The charging system charges a capacitor that discharges and forms a spark across the spark gap. The electrical measuring mechanism measures the discharge voltage of the capacitor and the controller compares it to a reference voltage, issuing a correction signal to the adjusting mechanism that repositions the electrodes, thus optimizing the spark gap. An alternate embodiment analyzes the charge and discharge characteristics of an electrode assembly that utilizes a second capacitor and an inductor to adjust the spark gap.

Claims

1. An electrode assembly, comprising:

an insulator having a generally cylindrical body and a hollow interior having a threaded inner surface;

an inner conductor disposed within said hollow interior and an outer conductor attached to the outer surface of said insulator;

an inner electrode being connected to said inner conductor,

an outer electrode cage being connected to said outer conductor,

an outer electrode being connected to said outer electrode cage, said inner and outer electrodes being opposed and coaxially aligned, said electrodes having tips, the distance between said tips defining a spark gap;

a first capacitor being connected to said inner and said outer conductors;

an electrical meter connected to said capacitor;

a device for adjusting the spark gap comprising a motor, a gearbox connected to said motor, and a threaded positioning element being engaged with said threaded inner surface of said insulator, said positioning element further being connected to said inner conductor; and

,

a controller being electrically connected to said motor, said capacitor, and said electrical meter, said controller comparing the discharge voltage of said capacitor to a predetermined reference value and issuing a correction signal to said motor when said discharge voltage differs from said predetermined reference value, whereby moving said tip of said inner electrode closer to or farther away from said tip of said outer electrode.

2. The electrode assembly of claim 1 further comprising:

a second capacitor electrically connected to said first capacitor and said meter;

said second capacitor being connected to said inner and outer conductors;

an inductor electrically connected to said first and said second capacitors;

whereby said controller compares the charge and discharge voltages of said second capacitor to predetermined reference values and issues a correction signal to said motor when said charge and discharges voltage differ from said predetermined reference values, whereby moving said tip of said inner electrode closer to or farther away from said tip of said outer electrode.

3. The electrode assembly according to claim 1 further comprising:

a groove formed in the outer surface of said insulator capable of receiving said outer electrode cage;

an inner locking ring slidably engaged with said electrode body, said inner locking ring for retaining said outer electrode cage within said groove;

an outer locking ring slidably engaged with said electrode body and with said inner locking ring, said outer locking ring for retaining said inner locking ring.

4. The electrode assembly according to claim 3 wherein said inner conductor further comprises a threaded end and said inner electrode further comprises a threaded end, said threaded end of said inner electrode being engaged with said threaded end of said inner conductor.

5. A lithotripter electrode assembly, comprising:

a insulator assembly comprising an insulator body, an inner conductor and an outer conductor;

an electrode arrangement comprising an inner electrode having a tip and an outer electrode having a tip, said inner and outer electrodes being coaxially aligned and said tips being in relatively close physical proximity wherein the distance between said tips define a spark gap, said inner electrode being electrically connected to said inner conductor and said outer electrode being connected to said outer conductor;

a charging system comprising at least one capacitor and a voltage source, said voltage source being electrically connected to said capacitor and said capacitor being electrically connected to said inner and outer conductors;

means for measuring a discharge voltage of said capacitor, said measuring means electrically connected to said charging system; and

,

means for adjusting said spark gap, said adjusting means being connected to said electrode arrangement and further being electrically connected to said measuring means, said adjusting means being responsive to a discharge voltage of said capacitor.

6. The lithotripter electrode assembly according to claim 5 wherein said measuring means comprises a voltage meter.

7. The lithotripter electrode assembly according to claim 5 wherein said measuring means comprises an oscilloscope.

8. The lithotripter electrode assembly according to claim 5 wherein said adjusting means comprises:

a motor;

a gearbox connected to said motor; and

,

a positioning element being connected to said gearbox and said inner conductor.

9. The lithotripter electrode assembly according to claim 8 wherein said adjusting means further comprises:

a controller being electrically connected to said motor, said capacitor, and said measuring means, said controller comparing the discharge voltage of said capacitor to a predetermined reference value and issuing a correction signal to said motor when said discharge voltage differs from said predetermined reference value, whereby moving said tip of said inner electrode closer to or farther away from said tip of said outer electrode.

10. The lithotripter electrode assembly according to claim 8 wherein said controller comprises a microprocessor.

11. A method of adjusting a spark gap of a lithotripter electrode assembly comprising the steps of:

applying a voltage to a first capacitor being electrically connected to a first conductor and a second conductor whereby creating a spark across said spark gap;

measuring the actual discharge curve of said spark created across said spark gap;

comparing said actual discharge curve with a predetermined reference curve; and

,

adjusting said spark gap based on a difference between said actual discharge curve and said reference discharge curve.

12. The method according to claim 11 further comprising the steps of:

applying the output voltage of said first capacitor to a second capacitor;

measuring the actual charge curve of said second capacitor;

comparing said actual charge curve of said second capacitor with a reference charge curve;

adjusting said spark gap based on a difference between said actual charge and discharge curves and said reference charge and discharge curves.

13. The method according to claim 12 wherein said steps of comparing comprising said actual charge and discharge curves with said reference charge and discharge curves comprise:

integrating said charge and discharge curve; and

,

inverting said charge and discharge curve;

whereby determining whether said spark gap is adjusted properly by determining whether said discharge of said second capacitor occurs within an acceptable range.

14. The method according to claim 13 further comprising the step of offsetting the actual charge and discharge curve by a −

50% of the reference voltage.

15. The method according to claim 12 wherein said step of adjusting said spark gap comprises:

issuing a correction signal from a controller to widen or narrow said spark gap.

16. A method of adjusting a spark gap of a lithotripter electrode comprising the steps of:

charging a first capacitor;

discharging said first capacitor into a second capacitor whereby charging said second capacitor until said second capacitor discharges across said spark gap;

measuring the actual charging and discharging voltages of said second capacitor;

comparing said actual charging and discharging voltages of said second capacitor with reference charging and discharging voltages; and

,

adjusting said spark gap based on a difference between said actual charging and discharging voltages of said second capacitor and said reference charging and discharging voltages such that a subsequent discharge of said second capacitor occurs at the maximum load of said second capacitor.

17. The method according to claim 16 wherein said steps of comparing said actual charge and discharge voltages with said reference charge and discharge voltages comprise:

integrating said charge and discharge voltages; and

,

inverting said charge and discharge voltages;

whereby determining whether said spark gap is adjusted properly by determining whether said discharge of said second capacitor occurs within an acceptable range.

18. The method according to claim 17 further comprising the step of offsetting the actual charge and discharge voltages by a −

50% of the reference voltage.

19. A method of adjusting a spark gap of a lithotripter electrode comprising the steps of:

creating a spark across said spark gap by charging a capacitor until said capacitor discharges across said spark gap;

measuring the actual discharging voltage of said capacitor;

comparing said actual discharging voltage of said capacitor with a reference discharging voltage; and

,

adjusting said spark gap based on a difference between said actual discharging voltages of said capacitor and said reference discharging voltages.

20. The method according to claim 19 further comprising the steps of:

discharging said capacitor to a second capacitor to create a spark across said spark gap; and

,

adjusting said spark gap based on a difference between said actual charging and discharging voltages of said second capacitor and said reference charging and discharging voltages.

21. The method according to claim 20 further comprising the steps of:

recording a succession of charges and discharge voltage values; and

,

statistically analyzing said succession of values to determine a representative voltage value; and

comparing said representative voltage value with a reference voltage value; and

,

adjusting said spark gap based on a difference between said representative voltage value with a reference voltage value.

22. The method according to claim 21 wherein said steps of comparing the representative voltage value with a reference voltage value comprises:

integrating said representative voltage values; and

,

inverting said representative voltage values;

whereby determining whether said spark gap is adjusted properly by determining whether said discharge of said second capacitor occurs within an acceptable range.

23. The method according to claim 22 further comprising the step of offsetting the actual representative voltage values by a −

50% of the reference voltage.

24. A lithotripter electrode assembly, comprising:

a insulator assembly comprising an insulator body and a pair of conductors;

an electrode arrangement comprising a pair of electrodes wherein the distance between said each of pair of electrodes defines a spark gap, said pair of electrodes being electrically connected to said pair of conductors;

a charging system comprising at least one capacitor and a voltage source, said voltage source being electrically connected to said capacitor and said capacitor being electrically connected to said pair of conductors;

means for measuring a discharge voltage of said capacitor, said measuring means electrically connected to said charging system; and

,

means for adjusting said spark gap, said adjusting means being connected to said pair of electrodes and further being electrically connected to said measuring means, said adjusting means being responsive to a discharge voltage of said capacitor.

25. The electrode assembly according to claim 24 further comprising a second capacitor wherein said adjusting means is responsive to charge and discharge voltages of said second capacitor.