| 摘要 |
PURPOSE:To stabilize the operation by preventing the phase angle of a load side circuit including a matching circuit from being largely changed, and preventing the change to the capacitive phase angle in particular. CONSTITUTION:The high-frequency current generated by the switching of FET 1, 2 is fed to an exciting coil 3 via a matching circuit constituted of capacitors C1, C2, CP and a coil L, and the electromagnetic energy generated on the exciting coil 3 is fed to an electrode-less lamp to light it. Since the values of the constituting elements of the matching circuit are properly set, the frequency characteristic of the phase angle of a load side circuit including the matching circuit forms a pure resistance or slightly inductive pole near the frequency of the high-frequency current. Even if this frequency or the values of the constituting elements of the matching circuit are somewhat drifted, the above phase angle is not changed so much, and a stable operation can be performed. Even when the drift is large, the phase angle is kept in the inductive range, thereby the FET 1, 2 do not break. |
