EP0359217A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Linear power control for ultrasonic probe with tuned reactance
Assignee: Alcon Vision LLC
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Filing: 1989-09-13
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Granted: —
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Expires: 2009-09-13
Abstract
Abstract There is disclosed herein a driver system for an ultrasonic probe for allowing a user to have proportional control of the power dissipated in the probe in accordance with the position of power dissipation controls operable by the user and for automatically tuning upon user request such that the driving frequency is equal to the mechanical resonant frequency of said probe and such that the reactive component of the load impedance represented by said probe is tuned out. The system uses a tunable inductor in series with the piezoelectric crystal excitation transducer in the probe which has a flux modulation coil. The bias current through this flux modulation coil is controlled by the system. It is controlled such that the inductance of the tunable inductor cancels out the capacitive reactance of the load impedance presented by the probe when the probe is being driven by a driving signal which matches the mechanical resonance frequency of the probe. The resulting overall load impedance is substantially purely resistive. The system measures the phase angle and monitors the load current. This information is used to determine the mechanical resonance frequency by sweeping through a band of driving frequencies and finding the peak load current where the slope of the load current versus frequency function is greater than a predetermined constant. After the automatic tuning to the resonant frequency, the system automatically adjusts the bias current flowing through the flux modulation coil to maintain the substantially purely resistive load impedance for changing power levels. There is also disclosed herein an analog circuit to measure the Phase angle for the load driving signal and to adjust the frequency of the driving signal for best performance. This system includes an integrator to eliminate the effect of offset errors caused by operational amplifiers.
Inventors
- 👤 Ying-Ching Lo
- 👤 Samuel Zambre
- 👤 Tolentino Escorcio
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 09:20
CPC Classifications
B; B06; B06B; B06B1/00; B06B1/02; B06B1/0207; A; A61; A61F; A61F9/00; A61F9/007; A61F9/00736; A61F9/00745; B06B1/0223; B06B1/0238; B06B1/0246; B06B1/0253; A61B; A61B18/00; A61B18/04; A61B18/12; A61B18/1206; A61B17/00; A61B2017/00017; A61B2017/00022; A61B2017/00084; B06B2201/00; B06B2201/40; B06B2201/50; B06B2201/55
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
151 words
A phacoemulsification apparatus for driving an ultrasonic handpiece including at least one crystal, comprising: driver means for supplying a variable frequency, variable amplitude electrical driving signal to said handpiece; an electrically tunable inductor means in said driver means for coupling to said crystal and altering the overall impedance of the combination of said handpiece and said tuning inductor; and frequency tuning means coupled to said driver means and to said electrically tunable inductor means, for electrically tuning said tunable inductor to be at a minimum inductance during a resonance tuning phase and for tuning the frequency of said driving signal until a peak in the load current drawn by said handpiece is found where the slope of the function load current versus frequency of driving signal at said peak satisfies a predetermined criteria, and for causing said driver means to drive said handpiece at the frequency of said peak load current.
Claim 2
Dependent Claim
151 words
A phacoemulsification apparatus for driving an ultrasonic handpiece including at least one crystal, comprising: driver means for supplying a variable frequency, variable amplitude electrical driving signal to said handpiece; an electrically tunable inductor means in said driver means for coupling to said crystal and altering the overall impedance of the combination of said handpiece and said tuning inductor; and frequency tuning means coupled to said driver means and to said electrically tunable inductor means, for electrically tuning said tunable inductor to be at a minimum inductance during a resonance tuning phase and for tuning the frequency of said driving signal until a peak in the load current drawn by said handpiece is found where the slope of the function load current versus frequency of driving signal at said peak satisfies a predetermined criteria, and for causing said driver means to drive said handpiece at the frequency of said peak load current.
Claim 3
Dependent Claim
71 words
The apparatus of claim 1 further comprising phase tuning means coupled to said frequency tuning means and to said electrically tunable inductor and to said driver means, for, upon completion of said resonance tuning phase, determining the phase difference between the drive current of said driving signal and said load current and for electrically tuning said tunable inductor to reduce said phase difference to within a predetermined range of zero degrees.
Claim 4
Dependent Claim
42 words
The apparatus of claim 1 wherein said frequency tuning means includes means to reject spurious peaks in said load current by comparing the slope of the load current versus frequency of every peak in load current to a predetermined minimum positive slope.
Claim 5
Dependent Claim
42 words
The apparatus of claim 2 wherein said frequency tuning means includes means to reject spurious peaks in said load current by comparing the slope of the load current versus frequency of every peak in load current to a predetermined minimum positive slope.
Claim 6
Dependent Claim
83 words
The apparatus of claim 1 wherein said driving means includes a voltage controlled oscillator for creating said driving signal and having a coarse tuning input for receiving a coarse tuning signal that alters the frequency of said driving signal by a first factor per unit change in said coarse tuning signal and has a fine tuning input for receiving a fine tuning signal that alters the frequency of said driving signal by a second factor per unit change in said fine tuning signal.
Claim 7
Dependent Claim
96 words
The apparatus of claim 5 wherein said frequency tuning means includes a computer controlled by software means for causing said computer to generate said coarse and fine tuning signals such that said load current peak is located by setting said coarse tuning signal at a predetermined value and then sweeping said fine tuning signal through a predetermined range, and, if said peak is not found, for setting said coarse signal at a new value and then sweeping said fine tuning signal through a predetermined range and for repeating the above steps until said peak is located.
Claim 8
Dependent Claim
83 words
The apparatus of claim 2 wherein said driving means includes a voltage controlled oscillator for creating said driving signal and having a coarse tuning input for receiving a coarse tuning signal that alters the frequency of said driving signal by a first factor per unit change in said coarse tuning signal and has a fine tuning input for receiving a fine tuning signal that alters the frequency of said driving signal by a second factor per unit change in said fine tuning signal.
Claim 9
Dependent Claim
96 words
The apparatus of claim 7 wherein said frequency tuning means includes a computer controlled by software means for causing said computer to generate said coarse and fine tuning signals such that said load current peak is located by setting said coarse tuning signal at a predetermined value and then sweeping said fine tuning signal through a predetermined range, and, if said peak is not found, for setting said coarse signal at a new value and then sweeping said fine tuning signal through a predetermined range and for repeating the above steps until said peak is located.
Claim 10
Dependent Claim
55 words
The apparatus of claim 6 wherein said frequency tuning means rejects said peak if said peak is found at a frequency lying within the upper or lower 25% of the range of frequencies which said driving signal can assume for any level of said coarse tuning signal and full excursion of said fine tuning signal.
Claim 11
Dependent Claim
55 words
The apparatus of claim 8 wherein said frequency tuning means rejects said peak if said peak is found at a frequency lying within the upper or lower 25% of the range of frequencies which said driving signal can assume for any level of said coarse tuning signal and full excursion of said fine tuning signal.
Claim 12
Independent Claim
216 words
An apparatus for driving an ultrasonically driven probe comprising: first means for generating a driving signal for said probe and having an input for receiving a first control signal to determine the frequency of said driving signal; second means coupled to said first means to occasionally determine the mechanical resonant frequency of said probe under then existing conditions and to generate said first control signal to tune said first means for generating a driving signal at said mechanical resonant frequency of said probe; a tuning inductor means for coupling said driving signal to said probe and having an input for receiving a second control signal which controls the amount of inductance of said tuning inductor and for changing inductance in accordance with said driving signal; means coupled to said tuning inductor and to said first means and to said second means for determining the actual phase angle between the driving signal for said probe and the resulting driving signal current and for determining the difference between said actual phase angle and a desired range of phase angles and for generating said second control signal to tune said tuning inductor to minimize said phase angle after said second means has tuned said first means to generate said driving signal at said mechanical resonance frequency of said probe.
Claim 13
Independent Claim
216 words
An apparatus for driving an ultrasonically driven probe comprising: first means for generating a driving signal for said probe and having an input for receiving a first control signal to determine the frequency of said driving signal; second means coupled to said first means to occasionally determine the mechanical resonant frequency of said probe under then existing conditions and to generate said first control signal to tune said first means for generating a driving signal at said mechanical resonant frequency of said probe; a tuning inductor means for coupling said driving signal to said probe and having an input for receiving a second control signal which controls the amount of inductance of said tuning inductor and for changing inductance in accordance with said driving signal; means coupled to said tuning inductor and to said first means and to said second means for determining the actual phase angle between the driving signal for said probe and the resulting driving signal current and for determining the difference between said actual phase angle and a desired range of phase angles and for generating said second control signal to tune said tuning inductor to minimize said phase angle after said second means has tuned said first means to generate said driving signal at said mechanical resonance frequency of said probe.
Claim 14
Dependent Claim
74 words
The apparatus of claim 11 wherein said second means includes means for determining said mechanical resonant frequency by sweeping the frequency of said driving signal through a predetermined range of frequencies and measuring the load current drawn by said probe and for selecting as said resonant frequency, that frequency where said load current is at a peak and the slope of a function relating load current versus frequency is greater than a predetermined value.
Claim 15
Independent Claim
163 words
A method of driving an ultrasonically driven probe comprising the steps of: (1) sending a driving signal having a frequency within a band of frequencies to be sent to said probe; (2) sampling and storing the amount of drive current drawn by said probe; (3) comparing said drive current sample to the highest drive current sample previously recorded for other drive signal frequencies in said band of frequencies; (4) calculating the slope of a function relating each drive current sample to the corresponding drive signal frequency for substantially all said drive current samples; (5) incrementing the frequency of said driving signal; (6) repeating steps 1 through 5 until a resonance frequency is found where the corresponding drive current sample is larger than all other drive current samples and wherein the slope of said function at said resonance frequency is greater than a predetermined constant selected to eliminate spurious current peaks caused by phenomena other than resonance from being mistaken as actual resonance peaks.
Claim 16
Independent Claim
163 words
A method of driving an ultrasonically driven probe comprising the steps of: (1) sending a driving signal having a frequency within a band of frequencies to be sent to said probe; (2) sampling and storing the amount of drive current drawn by said probe; (3) comparing said drive current sample to the highest drive current sample previously recorded for other drive signal frequencies in said band of frequencies; (4) calculating the slope of a function relating each drive current sample to the corresponding drive signal frequency for substantially all said drive current samples; (5) incrementing the frequency of said driving signal; (6) repeating steps 1 through 5 until a resonance frequency is found where the corresponding drive current sample is larger than all other drive current samples and wherein the slope of said function at said resonance frequency is greater than a predetermined constant selected to eliminate spurious current peaks caused by phenomena other than resonance from being mistaken as actual resonance peaks.
Claim 17
Dependent Claim
104 words
The method of claim 13 wherein said step of incrementing said frequency of said driving signal includes the steps of setting a coarse tuning signal at a predetermined value and incrementing a fine tuning signal to sweep through a range of frequencies defining a window, and if said resonance frequency is not found, for changing said coarse tuning signal to a new value and incrementing said fine tuning signal to sweep through a range of frequencies defining a new window, and repeating the above described steps until said resonance frequency is found, or a determination is made that said resonance frequency cannot be found.
Claim 18
Dependent Claim
53 words
The method of claim 14 wherein steps 5 and 6 include the steps of continuing to alter said coarse tuning and fine tuning signals until said resonance frequency is located within the center 50% of frequencies of any one of said windows or frequencies swept by the incrementation of said fine tuning signal.
Claim 19
Dependent Claim
32 words
the method of claim 15 wherein said step of altering said coarse tuning signal is carried out such that each said window of frequencies somewhat overlaps each other said window of frequencies.
References Cited (Backward Citations)
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