Ultrasonic generating system with feedback control
First Claim
1. In an ultrasonic generating system for treating living tissue, the combination which comprises:
- (a) electrically oscillating means having an input and output and arranged to produce an oscillating signal in the output which has the same frequency as the signal on the input thereof and a phase relationship with respect thereto of n×
180°
, where n is an integer;
(b) a piezoelectric crystal for translating ac energy into mechanical vibrations and vice versa, the crystal having excitation electrode means for receiving the ac energy and feedback electrode means for providing a feedback signal representative of the vibrations induced in said crystal;
(c) means for coupling the output of the oscillating means to the excitation electrode means of the crystal; and
(d) feedback means including filter means connected between the feedback electrode means and the input of the oscillating means to provide a closed loop around the oscillating means and the crystal, for filtering out harmonics from the feedback signal and for adjusting the amplitude of the feedback signal so that the gain around the loop is approximately unity;
whereby the frequency means is slaved to the resonant frequency of the crystals.
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Accused Products
Abstract
An ultrasonic generating system for coupling vibrating energy into a load, such as living tissue, has been described which employs a piezoelectric crystal having excitation electrodes on opposite faces thereof. A feedback electrode is disposed on one face of the crystal adjacent to and insulated from one of the excitation electrodes to provide a feedback signal between the feedback electrode and the other excitation electrode. A power supply is provided for applying excitation energy to the excitation electrodes. The feedback signal is utilized to slave the frequency of the power supply voltage to the resonant frequency of the crystal and to disable the power supply when the impedance of the load applied to the crystal rises above a predetermined level.
430 Citations
20 Claims
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1. In an ultrasonic generating system for treating living tissue, the combination which comprises:
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(a) electrically oscillating means having an input and output and arranged to produce an oscillating signal in the output which has the same frequency as the signal on the input thereof and a phase relationship with respect thereto of n×
180°
, where n is an integer;(b) a piezoelectric crystal for translating ac energy into mechanical vibrations and vice versa, the crystal having excitation electrode means for receiving the ac energy and feedback electrode means for providing a feedback signal representative of the vibrations induced in said crystal; (c) means for coupling the output of the oscillating means to the excitation electrode means of the crystal; and (d) feedback means including filter means connected between the feedback electrode means and the input of the oscillating means to provide a closed loop around the oscillating means and the crystal, for filtering out harmonics from the feedback signal and for adjusting the amplitude of the feedback signal so that the gain around the loop is approximately unity;
whereby the frequency means is slaved to the resonant frequency of the crystals.
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2. In an ultrasonic generating system for coupling vibratory energy into a load, the combination which comprises:
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(a) a piezoelectric crystal having two opposing faces and being arranged to translate electrical energy into mechanical vibrations and vice versa, the crystal having a resonant frequency; (b) an excitation electrode disposed on each of said two faces of the crystal; (c) power supply means for applying an ac output voltage to said excitation electrodes to cause said crystal to produce mechanical vibrations; (d) feedback means coupled to the crystal for providing a feedback signal representative of the frequency and magnitude of the mechanical vibrations transmitted to the load, the feedback means including at least one feedback electrode disposed on one face of the crystal and filter means to filter out harmonics of the resonant frequency to thereby provide a feedback signal having the crystal resonant frequency; and (e) coupling means for coupling the feedback signal to the power supply means, the power supply means being arranged to lock the frequency of the output voltage thereof to the frequency of the feedback signal. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. In a self-tuning ultrasonic generating system, the combination which comprises:
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(a) a piezoelectric crystal for translating electrical energy into mechanical energy vibrations and having a resonant frequency; (b) a pair of excitation electrodes disposed on the crystal and arranged so that an ac voltage applied across the excitation electrodes will cause the crystal to oscillate; (c) a feedback electrode disposed on the crystal and arranged so that a feedback signal representative of the magnitude and frequency of the crystal vibration is developed between the feedback electrode and one of said excitation electrode when the crystal vibrates; (d) oscillating means for applying an ac voltage across the excitation electrodes of the crystal to cause the crystal to oscillate and produce said vibrations; and (e) feedback means responsive to the feedback signal for filtering out harmonics of the resonant frequency from the feedback signal and for controlling the oscillating means to maintain the frequency of the ac voltage applied to the crystal at the resonant frequency. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification