| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting apparatus which has a comparatively simple structure and can easily detect a life terminal status of each of discharge lamps in an actual use and can conduct a suitable operation. <P>SOLUTION: The discharge lamp lighting apparatus includes a circuit 1 to rectify and smooth an alternate power source Vs, an inverter circuit 2 to convert the output into a high frequency wave and a controlling circuit 4 to control an operation of the inverter circuit 2, and also provided with a sweep status detecting circuit 5 to detect a required time from a preheating start-up till lighting of the discharge lamp FL or both end voltages of a discharge lamp FL just before the discharge lamp is lit by a method of sweep preheating/starting-up in which the frequency is reduced continuously and a memory circuit 6 to memorize at least a detected value of the sweep status detecting circuit 5 just after starting a use of the discharge lamp. When the detected value of the sweep status detecting circuit 5 is raised up to a predetermined variation ratio against the memorized detected value, the controlling circuit 4 judges that the discharge lamp FL completes its life and conducts a protection operation by controlling an output of or a stoppage of the inverter circuit 2. <P>COPYRIGHT: (C)2008,JPO&INPIT |
