| 摘要 |
PURPOSE:To light an electrodeless lamp stably while keeping impedance matching always to a load circuit. CONSTITUTION:FETs 2 and 3, a capacitor C3 and an excitation coil 5 constitute a Hartley self-exciting oscillation circuit. When electric power is supplied to the FETs 2 and 3 from an electric power supply circuit 1, the Hartley self- exciting oscillation circuit oscillates, and a high frequency current is supplied to the excitation coil 5, and an electrodeless lamp 6 is lighted. At this time, a phase detection circuit 10 impresses the high frequency current 100 and detection voltage corresponding to a phase difference of a 13.56MHz reference signal 50 outputted from an oscillation circuit 11 upon a voltage variable capacitance diode 14. Thereby, since the diode 4 changes the capacitance so that the phase difference becomes (0), matching of tank circuit side impedance of the Hartley self-exciting oscillation circuit and load impedance composed of the electrodeless lamp 6 and the excitation coil 5 can be maintained always, so that oscillation frequency of the high frequency current can be controlled always at 13.56MHz. |
