Patent ID: 6166494
Filing Date: 2000-12-26
Classification: H05B,Y02B

Abstract:
A drive circuit arrangement for a gas discharge lamp, comprisinga self resonating inverter for providing a drive voltage across a load having a reactive component, the inverter having a pair of field effect transistors which operate in anti-phase;a tank circuit for canceling the reactive component of a load impedance coupled to the inverter in use;a voltage division circuit which provides a given fraction of the drive voltage to the gates of the pair of field effect transistors in use; andphase shifting means for shifting the phase of the given fraction of the drive voltagewherein the voltage division circuit comprises a voltage limiter which in operation provides a further phase shift to the given fraction of the drive voltage when the drive voltage exceeds a given threshold value, thereby causing or permitting a resonant frequency of the inverter to increase and limit a peak drive voltage.