| 摘要 |
PROBLEM TO BE SOLVED: To make a fluorescent tube life longer and also to perform a stable control with some allowance by keeping enough control space. SOLUTION: A prescribed variable range Dd<=D<=Du is set for the duty ratio D in advance by lower limit voltage Ved and upper limit voltage Veu to error voltage Ve, where the duty ratio D of a driving signal Sc is controlled variably when the error voltage Ve is not less than the lower limit voltage Ved and not more than the upper limit voltage Veu, and at the same time, load current Ir is controlled to be at a targeted value by variably controlling frequency f of the driving signal Sc when the error voltage Ve is either less than the lower limit voltage Ved or greater than the upper limit voltage Veu. |
