| 摘要 |
PURPOSE:To reduce heat emission of a circuit element and suppress noise by sensing the temp. of the circuit element in a power supply circuit part, and limiting the output of a high frequency electromagnetic field when the sensed temp. exceeds a certain value. CONSTITUTION:High frequency voltage from an oscillator 1 is connected/ disconnected by a switching element Q1 of an amplifier part 2 to generate a high frequency electromagnetic field in a coil 4 through a resonance circuit, and a bulb 5 is lighted up. If in this condition the rare gas in this bulb 5 has leaked, or the coil 4 is separated from the bulb 5, the output impedance of a power supply circuit 10 decreases to provide light load condition, which raises the temp. of components. When temp. rise exceeds a certain level, a temp. fuse TF provided near matching capacitors C3-C6 of a matching part 3 blows off, and supply of the power to the amplifier part 2 from a DC power supply VCC is stopped. This reduces heat emission of the circuit element and suppresses noise. |
