| 摘要 |
PURPOSE:To lower loss and widen the control range by controlling a variable capacitance circuit connected to secondary coiled wire in series between a control terminals of a switching device and one main terminal by pulse width signal through an insulating means. CONSTITUTION:A capacitor 53 is charged with d.c. of a d.c. power source 21, a SSS55 is broken-over to turn a transistor 24 on, saturate a variable saturation transformer 27, and after that, transistors 23, 24 are turned on reciprocally to induce high frequency a.c. and light a discharge lamp 64. At the time of output control of a half-bridge-type inverter 40, the pulse width of the electric power source 71 is changed variably to change the light emitting time of light- emitting diodes of insulating means 38, 51 so as to pot out pulse width signals, on-time of photo-transistors 38s, 51a is changed to control the capacitance of variable capacitance circuits 31, 44, and the output of the inverter 40 is changed to change the lamp current flowing in the discharge lamp 64. |
