Lighting system for car, has lighting unit used as day running light, and another lighting unit used as night light, where control unit controls transistor to close or open power supply circuit of latter lighting unit

摘要

The system has a lighting unit (2) used as a day running light, and another lighting unit (3) used as a night light, where a power supply circuit (200) of the former lighting unit is connected to a power supply circuit (300) of the latter lighting unit. A controller (10) supplies a pulse width modulation (PWM) signal to the former lighting unit. A comparator (40) compares a value of a magnitude representative of a duty cycle of the PWM signal with a predetermined value. A control unit (41) controls a transistor (5) to close or open the power supply circuit of the latter lighting unit. The transistor is a bipolar transistor or a field effect transistor. An independent claim is also included for a method for controlling a power supply circuit of a lighting unit.