BALLAST CIRCUIT FOR HIGH VOLTAGE IC DRIVING HALF BRIDGE GAS DISCHARGE LAMP

摘要

PROBLEM TO BE SOLVED: To perform reliable lamp starting operation by using a ballast circuit for a gas discharge lamp by a high voltage integrated circuit constituted so as to generate a high voltage spike to start the lamp by deviating a frequency toward a natural resonance frequency of a resonance load circuit when the lamp is started. SOLUTION: A ballast circuit 10 to supply electric power to a gas discharge lamp contains switches S1 and S2 such as an electric power MOSFET connected between a bus bar conductor 12 and the earth 14 so as to receive DC bus bar voltage VBUS. The switches S1 and S2 are controlled by a high voltage integrated circuit(HVIC) 16, and a nodal point 18 is alternately connected to the bus bar voltage VBUS and the earth 14 by being alternately switched. Since a resonance load circuit 20 is connected to the nodal point 18, an alternating current is induced to the circuit 20.