| 摘要 |
PURPOSE:To lower loss and widen the control range by controlling the time constant of time constant circuits connected to control terminals of switching devices respectively in series by a level shifting means to agree the potential difference. CONSTITUTION:At the starting time, a capacitor 52 is charged with d.c. current of a d.c. power source 21, a SSS54 is broken-over turn a transistor 24 on, and after that, transistors 24, 23 are reciprocally turned on and off by a transformer 27 and time constant circuits 43, 31 to induce high frequency a.c. and light a discharge lamp 60. At the time of output control of a half-bridge-type inverter 22, the voltage of a variable voltage power source 62 is changed to convert it into pulse width signals by a V-PWM conversion circuit 63, the potential differences to be applied to each time constant are made same by a level shifting circuit 38, FET 33, 45 are turned on according to the pulse width signals, the on-time of the transistors 23, 24 is changed by controlling the electric charge to be charged in capacitors 32, 44, and the output of the inverter 22 is changed. |
