| 摘要 |
PURPOSE:To enable detection of the not-turn-on of a discharge lamp even in the daytime by detecting the turn-on and not-thin-on of the discharge lamp according to changes in the phase and the level of current fed to a ballast which uses as a reference the time at which source voltage becomes zero crossed. CONSTITUTION:In a turn-off detection device 1 for detecting the not-turn-on of the lamp 3 of a lighting device 2, a current detection means 12 detects the current value between a photoswitch 5 and a ballast 6 after a predetermined time elapses from when a zero cross detection means 11 detects zero cross from a voltage output from a rectifying circuit 9 connected to a power circuit 10. A judging means 13 determines whether the lamp 3 is turned on or not turned on according to the output of a means 12 which uses as a reference the time at which the source voltage becomes zero crossed, and the result of this judgement is displayed in an LED 14. Therefore, the not-turn-on of the lamp 3 can easily be detected even in the daytime and also inspection work can be promptly performed. |
