ULTRASONIC SCALER WITH ADAPTIVE AMPLITUDE

摘要

An automatic drive circuit for an ultrasonic probe, such as a dental scaler insert, is operative with a probe which includes a magnetostriction unit, an d a vibratory element to be set into vibration by the magnetostriction unit up on energizing of the magnetostriction unit with an alternating magnetic field. An energizing coil is enclosed within a handle having a compartment for receivi ng the probe. The coil is located within the handle adjacent to the probe receiving compartment for applying the alternating magnetic field to the magnetostriction unit upon insertion of the probe into the handle, and upon energizing the coil by the drive circuit. An oscillator of the drive circuit is coupled to the coil for applying an oscillatory current to the coil. The drive circuit includes a frequency sensor (72) for sensing a frequency of th e oscillatory current, the sensor outputting a signal designating a magnitude of the frequency. A further component of the drive circuit (16) establishes a value of amplitude of the alternating current in response to the sensed valu e of the frequency. The circuitry relies on the inductance introduced via the magnetostriction unit to the coil for automatically establishing the value o f oscillation frequency commanded by the probe.