| 摘要 |
PROBLEM TO BE SOLVED: To improve use safety and reliability by preventing flickering of a discharge lamp at the end of service life. SOLUTION: A service life detection part 7 detects the end of service life of a discharge lamp La based on a service life detection timer signal ST1 and a lighting judgement signal LGT given by a control circuit 6. A service life countermeasure part 8 gives to a control circuit 6, as a service life countermeasure signal, an output that becomes H when a service life detection signal builds up. When the service life countermeasure signal is at the level of H, the control circuit 6 is prohibited from relighting the discharge lamp La. If the discharge lamp dies out within a service life detection period T1, the service life detection part 7 instantaneously detects the end of service life of the discharge lamp La and the service life countermeasure part 8 prohibits the control circuit 6 from relighting the discharge lamp La, and therefore flickering of the discharge lamp La is prevented to improve safety and reliability in use. |
