| 摘要 |
PROBLEM TO BE SOLVED: To improve reliability of a headlamp device for a vehicle, using light-emitting diodes. SOLUTION: A diode array 1 is constituted by connecting a lot of light-emitting diodes D in series, and a current to be fed to the diode array 1 is controlled to be a predetermined target level, so that the current fed to each light-emitting diode D of the diode array 1 and the light emission quantity of each light-emitting diode D are maintained at that target level. A microcomputer 12 easily detects short-circuit fault of any one of light-emitting diodes based on the fluctuation in voltage drop making use of the fact that the fluctuation in voltage drop of a normal light-emitting diode is small due to the constant current control. COPYRIGHT: (C)2007,JPO&INPIT
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