Abstract:
In a method for seeking and setting a resonant frequency for a load impedance and a tuner for carrying out the method, a first frequency sweep is performed over a predetermined frequency interval in order to identify the resonant frequency within the predetermined frequency interval. To maintain the correct resonant frequency, regardless of signal drift and other interference, repeated sweeps are automatically performed within the predetermined frequency interval to identify the resonant frequency repeatedly. Alternating semi-sweeps can be performed to reduce the sweep duration.
Abstract:
An electrical apparatus for driving an ultrasonic piezoelectric crystal transducer in a surgical handpiece for the fragmentation and aspiration of tissue, which apparatus includes an electronic control loop in combination with a voltage source amplifier having an output which is connected to the piezoelectric crystal transducer with a tuning inductor in parallel. A control system for monitoring the control loop and a component for controlling tissue selectivity are also disclosed.
Abstract:
A nebulizer for use in administering a medicament to a patient undergoing treatment for example, comprises an ultrasonic piezo-electric transducer (60) and a transducer drive system (D) which is caused to drive said transducer at or near its anti-resonant frequency. There is also provided means to optimize nebulized fluid particle size and transfer to the patients lungs for example, by operating at an anti-resonant frequency in the range of 1.36 to 1.56 MHz and having a single outlet baffle and relatively short outlet tube (24) arrangement.
Abstract:
A device, which is especially made for the generation of shockwaves to detect inner-body objects, is equipped with piezo-ceramic transducer elements which act as an electro-acoustical transducer which can be driven by a high-voltage source with high-voltage impulses to generate shock waves or sound impulses through directed deformations and length changes of the transducer elements is dependent on the given polarization of the transducer elements and the polarity of the high-voltage impulses. The sound energy emitted by the device may then be especially high if the transducer elements are excited and biased with a bias potential before the appearance of a high-voltage impulse and the polarity of the bias potential is opposite to that of the high-voltage impulse.
Abstract:
A device for driving a piezoelectric vibrator is comprised of an AC power supply for supplying electric power to a piezoelectric vibrator for vibration thereof, a detecting device for detecting current supplied to the piezoelectric vibrator, and a driving circuit interposed between the AC power supply and the piezoelectric vibrator so as to decrease the electric power being supplied to the piezoelectric vibrator as the current flowing therethrough increases. This structure brings a decrease in electric power being supplied to the piezoelectric vibrator when current flowing therethrough is increased during resonance of the piezoelectric vibrator, thereby enabling the restriction or regulation of the expansion and contraction of the piezoelectric vibrator while maintaining resonance thereof.
Abstract:
In an ultrasonic generator the driver circuit of a piezoelectric converter is provided with a switching regulator under control of a microcomputer, the pulse duty factor and frequency of the switching regulator being controlled in response to the converter's impedance which is detected by means of a measuring circuit.
Abstract:
A pulsed power supply for providing power to a piezoelectric crystal. The power supply provides power to the piezoelectric crystal causing contraction of the crystal. Upon reaching a predetermined degree of contraction, the electrical voltage form the power supply is removed from the piezoelectric crystal by creating a short-circuit between the power supply and the crystal. Removal of electrical voltage from the crystal causes the immediate expansion of the crystal and a resulting energy wave.
Abstract:
An AC power system for a resonant load. A pair of switching networks and blocking networks are provided to drive the load for half a cycle in a resonant manner to a high energy state, and then maintained in that high energy state for a predetermined period. Then the load is driven for half a cycle in a resonant manner to the opposite polarity high energy state, and maintained in that high energy state for the predetermined period. A controller adjustably controls the frequency of switching between the two high energy states and the length of the predetermined period, so that a desired frequency is obtained.
Abstract:
An excitation circuit wherein the energy of a charged coil is discharged via a sound generator. A coil and a capacitance of the sound generator are tuned to one another such that a corresponding oscillatory frequency is identical to a predetermined resonant frequency of the sound generator.
Abstract:
A multiple tone signaling device provides a piezoelectric transducer, first, second and third oscillator circuits, a first input terminal for enabling either or both of the first and second oscillator circuits, circuitry coupling the third oscillator circuit to the first and second oscillator circuits for disabling either the first or second oscillator circuits in response thereto, and a second input terminal coupled to the third oscillator circuit for allowing control of the output of said third oscillator circuit.