| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent shortening of the lifetime of a hot cathode fluorescent lamp by appropriately controlling not only a lamp current but also a filament current in controlling the hot cathode fluorescent lamp after an inverter drive frequency is fixed. <P>SOLUTION: The lighting device includes a lamp lighting circuit 200 as an inverter circuit having a chopper circuit function, a filament preheating circuit 300 as an inverter circuit similarly having the chopper circuit function, and a control means 400 for driving switching elements included therein. The control means controls so that the chopper circuits in the two inverter circuits are driven at on times duty which are inverted mutually, and a chopper boosting ratio in the lamp lighting circuit 200 is larger than a chopper boosting ratio in the filament preheating circuit 300 in a lighting state, and the chopper boosting ratio in the filament preheating circuit 300 is larger than the chopper boosting ratio in the lamp lighting circuit 200 in a light controlled state. <P>COPYRIGHT: (C)2010,JPO&INPIT |
