Drive circuit for a piezo-electric element

摘要

A drive circuit for a piezo-electric element includes a blocking oscillator circuit which has a booster transformer with primary and secondary windings, an oscillation transistor the collector of which is connected to the primary winding of the booster transformer, and a biasing circuit via which a signal at the secondary winding of the booster transformer is fed back to the base of the oscillation transistor so as to produce oscillation by positive feedback. This drive circuit also includes an electric current control circuit means for restricting electric current from flowing through the oscillation transistor when the voltage at the secondary winding of the booster transformer has become equal to or greater than a certain value, and a rectifying element through which the piezo-electric element is connected to the secondary winding of the booster transformer. Optionally, there may be further included a discharge transistor means for rapidly discharging electric charge stored in the piezo-electric element when power input to the blocking oscillator circuit is discontinued. This drive circuit may be used in a relay for driving a piezo-electric element which makes and/or breaks contacts for connecting and/or breaking switched circuits.