| 摘要 |
PROBLEM TO BE SOLVED: To suppress deterioration of an electrode and extend the service life of a discharge lamp by comprising a main discharge circuit for supplying a heating current to each of a pair of electrodes of a discharge lamp, to apply a high voltage between the electrodes and a glow starter connected in parallel to the discharge lamp. SOLUTION: When a power switch 20 is turned on, a current is carried to a primary winding L11 or L12 of a leakage transformer Tr, and the electrodes 11, 12 of a fluorescent lamp are heated by the output current of filament windings F1, F2 to emit thermoelectrons. An output voltage is also generated in a main discharge circuit formed of the secondary winding L2 of the leakage transformer Tr, capacitors C1-C3 and a discharge resistor R to apply a high voltage between the electrodes 11 and 12 of the fluorescent lamp. At a stage where the thermoelectron quantity is insufficient, the current of the main discharge circuit is carried within a glow starter 21, so that no high voltage current is carried between the electrodes 11 and 12 of the fluorescent lamp, and the extension in service life of the fluorescent lamp can be thus attained without causing the deterioration of the electrode surface by sputtering. |
