| 摘要 |
PROBLEM TO BE SOLVED: To provide a lighting device for a vehicle, which can be turned on at constant brightness, without changing luminance of an LED, even if the number of LEDs is changed.SOLUTION: A lighting device 1 for a vehicle includes light sets 2a and 2b formed by connecting a plurality of LEDs in series, a step-down circuit 61 for decreasing source voltage to the lowest lighting voltage required for turning on one LED constituting the light sets, a constant current circuit 62 for determining whether the voltage to the light sets is sufficient for turning on all the LEDs constituting the light sets, and a boosting circuit 63 for increasing the lowest lighting voltage until the constant current circuit 62 determines that the voltage is sufficient for turning on all th LEDs constituting the light sets, and outputting it to the light sets. |
