Abstract: The invention relates to a method for controlling an ultrasonic unit f an ultrasonic cleaning system with at least one control unit, one generator unit and one hand-held unit containing the ultrasonic unit and one switching module provided for starting the ultrasonic unit, wherein mechanical oscillations can be generated via the ultrasonic unit and transmitted to an instrument that is mechanically connected to the ultrasonic unit. In a preferred embodiment, the resonant frequency required for operation of the ultrasonic unit in resonance is determined by a control routine executed in the control unit, and a control signal (ss) based on the determined resonant frequency is generated in the generator unit and is sent to the ultrasonic unit for operation of the ultrasonic unit in resonance.

Abstract: A control and drive unit selectively provides either ultrasonic or high frequency energy to a single handle which contains a coil-driven oscillator capable of driving a cleaning or surgical tool. A changeover switch connects the selected signal to the handle and a single control is effective to control either frequency range. A water supply, coupled to the single control, is actuated when a predetermined level of signal power is attained.

Abstract: Ultrasonic tooth treatment apparatus having an electromechanical transducer, such as a magnetostrictive or piezeoelectric transducer, and a generator which drives the transducer, with a control signal derived from a change of current and/or frequency occurring upon loading the transducer. This signal disconnects the generator or reduces its power when a predetermined threshold value is exceeded. The generatory may be readjusted to the actual resonant frequency of the transducer. The transducer may be part of the frequency-determining portion of the generator. The generator supplies a pulse-shaped or sinusoidal signal for driving the transducer. A first signal corresponding to the no-load frequency or the no-load current of the transducer is derived.