| 摘要 |
PROBLEM TO BE SOLVED: To easily detect a tube current even in opening a tube, to freely set the number of windings, a capacity of a resonant capacitor, or the like, and to increase designing freedom. SOLUTION: The discharge tube is lit by impressing high voltage from a secondary winding of a transformer 14 of a separately excited inverter on a cold-cathode tube 18. A first resistor R1 is connected in series with a low-voltage side of the secondary winding of the transformer to ground, a second resistor R2 is connected in series with a resonant capacitor 16 arranged in parallel with the secondary winding of the transformer to ground, and their mid-point voltage is taken out. The first resistor detects a voltage generated by a tube current and a resonant current, the second resistor detects a voltage generated by the resonant current, and a voltage generated at the resonant current is offset to detect the tube current. COPYRIGHT: (C)2007,JPO&INPIT |
