Patent
Control circuit for an ultrasonic dental scaler
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TLDR
In this article, a control circuit for an ultrasonic dental scaler, comprising a transducer driven by a frequency-controlled oscillator, is presented, which is used for continuously regulating the oscillator frequency at substantially the same value as the resonant frequency of the transducers with a dental tool attached to it.Abstract:
A control circuit for an ultrasonic dental scaler, comprising a transducer driven by a frequency-controlled oscillator, is disclosed. The control circuit is operable for continuously regulating the oscillator frequency at substantially the same value as the resonant frequency of the transducer with a dental tool attached to it and for controlling the mechanical power output of the transducer. The transducer can be drivingly connected to a work tool for transmitting mechanical energy thereto. The regulation of the oscillator frequency is accomplished by simultaneously applied control signals derived from the current passing through the transducer and from the voltage across the transducer, to compensate for supply voltage variations. Moreover, the mechanical power output of the transducer is controlled such that it is reduced whenever the contact pressure of the work tool exceeds a predetermined maximum value. Such excessive pressure is monitored as the amplitude or phase variation of the voltage or of the current of the transducer.read more
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References
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Patent
Load-sensitive generator for driving piezo-electric transducers
TL;DR: In this article, the first stage of a two-stage oscillatory circuit comprises the sum of three feedback components plus a DC forward bias, which is used to adjust the output power of the transducer.
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Visual tuning electronic drive circuitry for ultrasonic dental tools
TL;DR: In this paper, the magnetostrictive transducer of ultrasonic dental tools is controlled by circuit adjustment to maximum brightness of a tuning indicator lamp, which is achieved by feeding a reference voltage proportional to the excitation current flowing through the transducers to the input of a differential amplifier stage to compare it with a preset reference voltage.