| 摘要 |
PROBLEM TO BE SOLVED: To provide a high frequency lighting device for a fluorescent lamp in which a high voltage output can be provided at the time of starting, which is compact and thin, and which is of high efficiency and high safety. SOLUTION: If a fluorescent lamp is being started or normally lighted is determined by action of a current detection circuit 4 and a control circuit 5, a changing circuit 3 acts based on result to select on/off of FETs 21, 22, 23 of a drive circuit, so a boosting ratio of a boosting transformer 1 is increased at the time of starting to provide a high voltage output required for starting, while the boosting ratio of a boosting transformer of a lighting device is decreased at the time of normal lighting to provide with good efficiency a low voltage output as the minimum required for maintaining discharge of a fluorescent lamp. As a frequency deciding circuit 7 acts by a changing signal S1 from the control circuit 5, the boosting transformer 1 can be driven by a drive signal of a resonance frequency decided by a current way of the boosting transformer 1, and additionally, starting or maintaining discharge can be efficiently performed. |
