Illumination device in vehicle has controller driving power semiconductor with PWM signal, whereby duty cycle is controllable depending on detected supply voltage for constant light power

摘要

The device has at least one lamp (9,10) for connection to a voltage supply, a switchable power semiconductor (7,8) between the lamp and supply, a device (4) for detecting the supply voltage and a controller (5) connected to a power semiconductor control input and the measurement device. The controller can drive the power semiconductor with a PWM signal; the duty cycle is controllable depending on detected supply voltage for constant light power.