An inverter circuit for a discharge tube comprising: a leakage flux type step-up transformer having an elongated core disposed in substantially a center of said step-up transformer, a primary winding and a secondary winding, said primary winding and secondary winding being wound about said elongated core in juxtaposed relation with each other along said core so that said secondary winding has a portion near to said primary winding which magnetically close couples with said primary winding and a portion remote from said primary winding which magnetically loose couples with said primary winding; a discharge tube connected across said secondary winding; and a resonance circuit composed of a parasitic or stray capacitance produced mainly in the close coupling portion of said secondary winding, the loose coupling portion of said secondary winding, and a parasitic or stray capacitance produced in the circumference of said discharge tube, said resonance circuit producing a high voltage by the resonance thereof that is supplied to said discharge tube in order to turn said discharge tube on. view more

The inverter circuit according to claim 4, further including a capacitor connected in parallel with said discharge tube.