| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent unlighting in case a main lamp is deteriorated or failed by releasing a fixing of a lamp holder on the occurrence of the unlighting of the main lamp, and carrying a current to a back-up lamp by an illumination instantaneous switching unit. SOLUTION: The straight tube-type main lamp LA and back-up lamp LB are held in parallel with one another between a pair of supporting parts 4a of a fixing frame 4 by a lamp holder 5. An illumination instantaneous switching unit 2 is fixed to a rear surface side of a fixing frame 4. The illumination instantaneous switching unit 2 is connected to the conductors respectively extended from the output terminals of the lighting auxiliary circuits to the main lamp LA and the back-up lamp LB. When the unlighting of the main lamp LA is detected by an unlighting detecting means, the illumination instantaneous switching unit 2 instantaneously supplies the power to the backup lamp LB to light the same. When the lighting is switched from the main lamp LA to the back-up lamp LB, the main lamp LA in the unlighting state is moved, and the back-up lamp is moved there.</p> |
