The present invention relates to methods for velocity control of transducers that can compensate both for age related changes as well as the more immediate changes that occur during operation. In one aspect of the invention, the non-motional reactive current is measured at two predetermined frequencies, one below (Ilf) and one above the resonance frequency (Ihf). A correction factor is calculated from these measured currents is used to maintain a specified value of end effector velocity or displacement. In another aspect of the invention, methods are provided for the detection of secondary resonances that could be indicative of end effector fault conditions. In another aspect of the invention, velocity control is achieved.

Ultrasonic transducer control method and system

The apparatus includes an ultrasonic transducer having a hand piece, an ultrasonic vibrating element secured to the hand piece and a probe coupled with the hand piece for propagating the ultrasonic oscillation produced by the ultrasonic vibrating element, a driving circuit for producing a driving signal for the ultrasonic vibrating element, a voltage controlled amplifier for amplifying the driving signal, an impedance matching transformer having a plurality of primary windings connected to the output of the voltage controlled amplifier via a switching circuit and a secondary winding connected to the ultrasonic vibrating element, a probe identification circuit for detecting the probe connected to the hand piece to produce a probe identification signal, a feedback control loop for generating a control voltage which is applied to the voltage controlled amplifier for controlling the amplification factor thereof in accordance with a driving current of the driving signal, an impedance detecting circuit for detecting the impedance of the ultrasonic transducer and controlling, the switching circuit such that a given primary winding is connected to attain the impedance matching between the driving circuit and the ultrasonic transducer, and a voltage limiter arranged in the feedback control loop such that the maximum value of the control voltage is limited in accordance with the probe identification signal.

Apparatus for generating ultrasonic oscillation

A switched resonant power amplifier system for ultrasonic transducers is disclosed. The system includes an amplifier that receives and processes a driver output signal for generating a drive signal that is provided to an ultrasonic device for controlling output of the ultrasonic device. An output control circuit receives and processes a signal related to a feedback signal generated by the ultrasonic device and a divider reference signal, and generates a compensated clock signal that is adjusted for at least one of phase and frequency differences between the received feedback signal and the divider reference signal. A compensated drive circuit receives and processes the compensated clock signal for generating the divider reference signal, and for generating the driver output signal.

Switched Resonant Ultrasonic Power Amplifier System

An ultrasonic driving apparatus consists mainly of a digital oscillatory circuit, an amplifier, a detection circuit, a phase difference detection circuit, a register, a data transfer circuit, and a switching circuit. The digital oscillatory circuit is used to drive an ultrasonic transducer at the resonance frequency of the ultrasonic transducer. The amplifier amplifies a driving signal output from the digital oscillatory circuit. The detection circuit detects the phase θv of an applied voltage and the phase θi of an induced current from the driving signal applied to the ultrasonic transducer via the amplifier. The phase difference detection circuit detects a difference between the phases θv and θi. The register holds digital frequency data with which a frequency at which the digital oscillatory circuit is oscillated is determined, and changes the digital frequency data. The data transfer circuit transfers the digital frequency data to the register. The switching circuit is interposed between the phase difference detection circuit and register.

Ultrasonic operation apparatus for performing follow-up control of resonance frequency drive of ultrasonic oscillator by digital PLL system using DDS (direct digital synthesizer)

A system and method for tuning and controlling ultrasonic handpieces by incorporating a broad-spectrum signal as at least a component of the signal used to drive the handpiece. The response of the handpiece to this broad-spectrum signal is measured and the frequency or amplitude or both of the drive signal are adjusted in order to maintain the desired level of handpiece performance. The operation of the systems and the performance of the methods described enables the handpiece to be operated in a most effective manner over a more widely varying range of mechanical load and thermal conditions than was possible through the use of prior control systems and methods.

System and method for tuning and controlling an ultrasonic handpiece

An ultrasonic power supply for driving a piezoelectric transducer at its parallel resonant frequency includes a clamped-mode resonant converter for converting direct current to alternating current and a demodulator, a loop filter and a voltage controlled oscillator in a phase locked loop configuration. The power supply also includes a control circuit for adjustably setting and controlling the amplitude of vibration of the transducer, and providing during start-up a ramp start. The power supply, further, includes a control circuit for limiting the maximum permissible current flow to the transducer and the reverse current flow from the transducer resulting from stored mechanical energy. Both control circuits provide feedback signals which control the pulse width modulated operation of the clamped-mode resonant converter and thereby control the voltage amplitude of the alternating current output from the converter. The phase locked loop circuit causes the frequency of the alternating current output from the converter to track the parallel resonant frequency of the transducer.

Ultrasonic power supply

La presente invention concerne une alimentation pour transducteur piezo-electrique. Cette alimentation est caracterisee en ce qu'elle comporte une alimentation en courant continu (10), un convertisseur (100) pour fournir un courant alternatif en sortie, pour faire fonctionner un transducteur piezo-electrique (18) a sa frequence de resonance propre, un reseau de sortie (200), un filtre de courant (700), un demodulateur (800), un filtre de boucle (900), un oscillateur (300) commande en fonction de la tension et un circuit modulateur et d'attaque (400).

Circuit d'alimentation electrique pour un transducteur piezo-electrique.

A clamped-mode resonant converter converts direct current to alternating current. The power supply also includes a control circuit for adjustably setting and controlling the amplitude of vibration of the transducer, and providing during start-up a ramp start. - The supply, further, includes a control circuit for limiting the maximum permissible current flow to the transducer and the reverse current flow from the transducer resulting from stored mechanical energy. Both control circuits provide feedback signals which control the pulse width modulated operation of the clamped-mode resonant converter and thus control the voltage amplitude of the alternating current output from the converter. A phase locked loop circuit causes the frequency of the alternating current output from the converter to track the parallel resonant frequency of the transducer.

Ultrasonic power supply - includes control circuit to adjust amplitude of vibration of transducer providing ramp start-up, used for thermoplastic welding

Allan J Roberts

Papers

Ultrasonic power supply

Circuit d'alimentation electrique pour un transducteur piezo-electrique.

Ultrasonic power supply - includes control circuit to adjust amplitude of vibration of transducer providing ramp start-up, used for thermoplastic welding