Energizing circuit for ultrasonic transducer

An energizing system for automatically driving an electronic transducer at its resonant frequency, comprising:

• resonant circuit means for applying an electrical signal of a desired frequency to the transducer, the transducer having electrodes constituting a capacitive element of said resonant circuit and a secondary winding of a transformer constituting an inductive element of said resonant circuit, and the transducer itself acting as a series RLC circuit disposed in parallel with the capacitive and inductive elements of the resonant circuit means;
• and
• driver circuit means inductively coupled with said resonant circuit means for driving said resonant circuit means at the resonant frequency of the transducer, said driver circuit comprising:
• an inductive element coupled with said transformer secondary winding comprising the primary winding of said transformer;
• switching circuit means connected between a power supply and said transformer primary winding;
• control circuit means responsive to the magnitude and frequency of the electrical signal applied to said transducer for monitoring the impedance of said resonant circuit means and producing a control signal related to the difference between the impedance of said resonant circuit means and the minimum impedance of said resonant circuit means occurring when the transducer is vibrating at its resonant frequency;
• and
• oscillatory circuit means operably coupled with said control circuit means and said switching circuit means, said oscillatory circuit means producing an oscillating switching signal in response to said control signal to actuate said switching circuit means to supply a driving signal to said transformer primary winding at the resonant frequency of the transducer.