Field studies on the flickering and stroboscopic effects of pulse-width modulated LED front lighting systems

摘要

Dimming of the amount of LED power is mainly realized by pulse-width modulation at frequencies above the flicker fusion frequency. In certain dynamic situations, the flicker of the PWM dimmed LED lighting can be perceived indirectly through the stroboscopic effect. This research focuses on investigation of factors influencing its perception: frequency and duty cycle. The studies was conducted in real traffic situations. In the pretest, a constructed lighting system based on series headlamp LED-modules was used. A further test was performed using a series vehicle with LED headlamps. Subjects reported whether they could detect the stroboscopic effect at different PWM signals. Results show most naive participants do not perceive this effect under normal driving conditions. Only when subjects specially perform rapid eye movements, this effect occurs. It decreases with rising frequency and rising duty cycle.