| 摘要 |
PROBLEM TO BE SOLVED: To detect precisely the anomalies like ending life of a fluorescent lamp for exclusive use for high-frequency lighting, and to provide alighting device for fluorescent lamps which can maintain a desirable illumination condition. SOLUTION: This lighting device comprises the first and second switching elements connected in series, the first and second lighting circuits including a resonance circuit connected in parallel with the second switching element and a fluorescent lamp for exclusive use for high-frequency lighting, the first and second detection circuits which detect circuit voltage of each lighting circuit and output an anomaly signal only when the circuit voltage reaches the set value, the first and second retaining circuits which retain the output from each detection circuit, and a control circuit structured to enable to change frequencies of drive signals given to each switching element in accordance with various action modes of each lighting circuit including a dimming mode. When anomalies occur in each lighting circuit, the above control circuit controls the frequency of drive signals so that it may become the frequency at the time of a holophotal condition by anomaly signals from each retaining circuit, even in a dimming mode. |
