To easily prevent flickering of a lamp.
When a power supply source 2 for the lamp 3 and that for a load 11 are identical, using a power source voltage Vin from the power supply source 2, the lamp 3 is lit and driven by PWM control basing on a PWM signal S. At that time, a duty ratio of the PWM signal S is changed according to fluctuation of the power source voltage Vin from the power supply source 2. Frequency of the PWM signal S is at least 50 Hz or higher. Frequency of the PWM signal S at the time of starting driving of the other load 11 is set higher than that of the PWM signal S at the stationary time. Thereby, when the power source voltage Vin rapidly fluctuates due to starting of the other load 11, duty correction is performed more frequently than the stationary time, and visual flickering of the lamp is prevented.
COPYRIGHT: (C)2004,JPO
Yasuyuki Komatsu
Tadashi Fujiwara
Shigeru Aoki
SUMITOMO WIRING SYSTEMS,LTD.
Sumitomo Electric Industries, Ltd.
Honda motor industry stock company
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Takahiro Arita