| 摘要 |
PROBLEM TO BE SOLVED: To provide an electronic ballast for igniting and maintaining a discharge arc in a discharge tube of a ceramic metal halide lamp. SOLUTION: This electronic ballast 10 includes an oscillation inverter circuit 11d, driving an LC tank circuit network 51 connected to the discharge tube 100, and the LC tank circuit network is provided with a ballast circuit, with which a time-variable voltage having a peak peak value determined by an oscillation frequency of the inverter circuit is impressed to the discharge tube, and an electric power regulating circuit connected to the inverter circuit for changing the oscillation frequency of the inverter circuit, so that the power impressed to the discharge tube stays inside a predetermined desired power value range while resistance of the discharge tube fluctuates according to a temperature during the operation of the discharge arc. |
