US6480796B2
Expired / Lapsed
US
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Method for improving the start up of an ultrasonic system under zero load conditions
Assignee: Ethicon Endo Surgery Inc
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Filing: 2001-05-25
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Granted: 2002-11-12
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Expires: 2021-05-25
Abstract
Abstract The start up performance of an ultrasonic system under zero load conditions is improved by setting a phase set point in a frequency control loop such that, at start up under zero load conditions, the phase set point intersects a point on a phase-frequency response curve which has a low positive slope. This intersection point on the phase-frequency response curve changes as the load is increased and the system Q is decreased. The controller “seeks” a target 0° impedance phase angle. The frequency of the ultrasonic generator is set to an off-resonance frequency which is lower than the resonance of any known hand piece/blade combination. In order for the drive voltage to not exceed the physical limit of the system, the drive current is set to a low level. The drive frequency is then smoothly increased in steps until the target 0° impedance phase delta is located.
Inventors
- 👤 Eitan T. Wiener
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:13
CPC Classifications
A; A61; A61B; A61B17/00; A61B17/32; A61B17/320068; B; B06; B06B; B06B1/00; B06B1/02; B06B1/0207; B06B1/0223; B06B1/0238; B06B1/0246; B06B1/0253; A61B2017/00017; A61B2017/00022; A61B2017/00026; A61B2017/00681; A61B2017/00725; A61B2017/320069; A61B2017/320071; A61B2017/320082; A61B2017/320089; B06B2201/00; B06B2201/70; B06B2201/76
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
130 words
A method for improving start up performance of an ultrasonic surgical system under zero load conditions, comprising the steps of: exciting a hand piece/blade with a drive current using an ultrasonic generator at an initial drive frequency; setting a frequency of a direct digital synthesis circuit located in the generator to an off-resonance frequency of the hand piece/blade; setting the drive current to a low level; searching for a target 0° impedance phase angle; increasing the drive frequency to a new level; maintaining the target 0° impedance phase angle at a constant value; monitoring impedance and phase angle magnitude values of the drive signal at the new level to calculate a frequency correction value; and correcting the frequency of the direct digital synthesis circuit using the calculated frequency correction value.
Claim 2
Independent Claim
130 words
A method for improving start up performance of an ultrasonic surgical system under zero load conditions, comprising the steps of: exciting a hand piece/blade with a drive current using an ultrasonic generator at an initial drive frequency; setting a frequency of a direct digital synthesis circuit located in the generator to an off-resonance frequency of the hand piece/blade; setting the drive current to a low level; searching for a target 0° impedance phase angle; increasing the drive frequency to a new level; maintaining the target 0° impedance phase angle at a constant value; monitoring impedance and phase angle magnitude values of the drive signal at the new level to calculate a frequency correction value; and correcting the frequency of the direct digital synthesis circuit using the calculated frequency correction value.
Claim 3
Dependent Claim
32 words
The method of claim 1 , wherein the step of setting the drive current to a low level comprises the step of: applying a drive current having a level of 100 ma.
Claim 4
Dependent Claim
59 words
The method of claim 1 , wherein the step of searching for a target 0° impedance phase angle, comprises the step of: increasing the drive frequency smoothly in predetermined steps until the target 0° impedance phase angle is located; wherein the drive frequency is smoothly increased to avoid impedance magnitude and impedance phase angle oscillations of the hand piece/blade.
Claim 5
Dependent Claim
24 words
The method of claim 3 , wherein the predetermined step is 20 Hz and is applied at a rate of at least 2 kHz.
Claim 6
Dependent Claim
33 words
The method of claim 1 , wherein said calculation of the frequency correction value is performed in accordance with a phase-slope vs. impedance relationship of a hand piece at 0° impedance phase angle.
Claim 7
Dependent Claim
44 words
The method of claim 5 , wherein the phase-slope vs. impedance relationship comprises the relationship: f Δ =Φ*phase_slope (|z|)*k, wherein f Δ is the calculated frequency correction value, Φ is a phase reading, z is impedance in ohms, and k is a scaling factor.
Claim 8
Dependent Claim
21 words
The method of claim 6 , wherein the scaling factor is a fractional number having a magnitude of less then 1.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2005-11-11 | 2006-05-13 | 2006-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2009-11-11 | 2010-05-13 | 2010-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2013-11-11 | 2014-05-13 | 2014-11-12 | $7700.00 | Window Closed / Lapsed |