| 摘要 |
PROBLEM TO BE SOLVED: To light on a light source by preventing further reduction of an input voltage when the input voltage from a direct current supply line is reduced since impedance of the direct current supply line increases. SOLUTION: A light source lighting device 1 is connected to a direct current power supply E via a pair of the direct current supply lines Wdc, and lights on a light source 2 by receiving electric power supply from the direct current power supply E. A measuring means switches a first operation state and a second operation state which are mutually different in light output of the light source 2, and measures the impedance of the direct current supply lines Wdc by dividing a differential between the input voltage Vin in the first operation state and the input voltage Vin in the second operation state by the differential between the input current Iin in the second operation state and the input current Iin in the first operation state. A control means makes the light output of the light source 2 as the light output at the time of stationary lighting if the impedance of the direct current supply lines Wdc measured by the measuring means is not a prescribed threshold value or more, and makes the light output of the light source 2 lower than that at the time of the stationary lighting if it is the threshold value or more. COPYRIGHT: (C)2009,JPO&INPIT |
