To provide an on-vehicle lamp lighting control circuit which executes the lighting control of a plurality of on-vehicle lamps in adequate brightness without complicating its wiring structure.
When the pulse width of the pulse voltage is variable, and a kind of a plurality of on-vehicle lamps with the common pulse voltage being supplied thereto are different, a relay switch 21 is connected in series to on-vehicle lamp, for example, a light emitting diode L3 of a license plate lamp 11. When the pulse voltage to be supplied from a lamp drive circuit 1 is of the short pulse shape, the switch is set to be in a constantly contact state, and the pulse voltage from the lamp drive circuit 1 is supplied to the light emitting diode L3. Further, when the pulse voltage to be supplied has a duty ratio of 100%, the relay switch 21 is subjected to PWM (Pulse Width Modulation) drive, and the pulse voltage is supplied to the light emitting diode L3.
SUMITOMO WIRING SYSTEMS
SUMITOMO ELECTRIC INDUSTRIES