ULTRASONIC SURGICAL SYSTEM
First Claim
1. An ultrasonic surgical system including a controllable ultrasonic energy generator, a hand piece with a blade that is vibrated at an ultrasonic resonance frequency rate by energy from the generator, and a switch for indicating to the generator the amplitude and frequency of the energy supplied to the hand piece, said ultrasonic generator comprising:
- an analog input drive signal generator which generates an input drive signal having an amplitude and frequency;
an amplifier which receives the analog input drive signal and supplies the energy to the hand piece through a line in response thereto;
a current sensor that senses the current in the line and produces a current signal related thereto;
a comparator which compares the current signal to a variable preset current value and produces a difference signal that is applied to the analog input drive signal generator so as to change the amplitude of the drive signal to cause the current signal to match the preset value;
a voltage sensor which senses the voltage on the line and produces a voltage signal related thereto;
a digital phase detector which compares the current signal to the voltage signal and generates a digital phase code related to the phase difference between them;
a digital impedance detector which compares the ratio of the voltage signal to the current signal and generates a digital impedance code related thereto;
a digital controller which receives the digital phase code and the digital impedance code and produces a digital frequency code in response thereto which is at a frequency which represents the resonance of the hand piece; and
a direct digital synthesis circuit for converting the digital frequency code to an analog frequency signal that is applied to the analog input drive signal generator so as to maintain the frequency at the resonance frequency.
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Accused Products
Abstract
An ultrasonic surgical system utilizes a digital control system to generate ultrasonic drive current for transducers that are located in a hand piece and are attached to a surgical scalpel or blade in the hand piece so as to vibrate the blade in response to the current. The digital control includes a digital signal processor (DSP) or microprocessor; a direct digital synthesis (DDS) device; a phase detection logic scheme, a control algorithm for seeking and maintaining resonance frequency; and design scheme that allows to regulate current, voltage, and power delivered to an ultrasonic thereby a device. Such system allows the power versus load output curve to be tailored to a specific hand piece, which improves efficiency and reduces heat. Further, the components of the digital system are much less sensitive to temperature variations, thereby allowing it to operate with narrow as needed frequency range around the desired resonance in order to avoid excitation of other resonances. Also, the digital system provides increased flexibility in locating the resonance frequency of the blade and running diagnostic tests. The start of a user initiated diagnostic test that requires movement of the blade is caused by operating two of the system switches, which guards against accidental operation of the blade which could be harmful if in contact with tissue and also generate false diagnostic results. In addition, the system has interlock with an Electrosurgical unit so that it is not effected by the electromagnetic interference generated by that unit.
81 Citations
14 Claims
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1. An ultrasonic surgical system including a controllable ultrasonic energy generator, a hand piece with a blade that is vibrated at an ultrasonic resonance frequency rate by energy from the generator, and a switch for indicating to the generator the amplitude and frequency of the energy supplied to the hand piece, said ultrasonic generator comprising:
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an analog input drive signal generator which generates an input drive signal having an amplitude and frequency; an amplifier which receives the analog input drive signal and supplies the energy to the hand piece through a line in response thereto; a current sensor that senses the current in the line and produces a current signal related thereto; a comparator which compares the current signal to a variable preset current value and produces a difference signal that is applied to the analog input drive signal generator so as to change the amplitude of the drive signal to cause the current signal to match the preset value; a voltage sensor which senses the voltage on the line and produces a voltage signal related thereto; a digital phase detector which compares the current signal to the voltage signal and generates a digital phase code related to the phase difference between them; a digital impedance detector which compares the ratio of the voltage signal to the current signal and generates a digital impedance code related thereto; a digital controller which receives the digital phase code and the digital impedance code and produces a digital frequency code in response thereto which is at a frequency which represents the resonance of the hand piece; and a direct digital synthesis circuit for converting the digital frequency code to an analog frequency signal that is applied to the analog input drive signal generator so as to maintain the frequency at the resonance frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification