Daytime visibility represents one of the most important themes in automotive safety. Some accidents, especially frontal collisions, used to occur as a result of a bad recognition of vehicle presence. In order to keep vehicles more visible during the day, there is a luminous device called Daytime Running Lamp (DRL). Nowadays DRL is not mandatory in Brazil, but it will be in 2021 for new vehicles. As with any situation that involves technological transitions, some questions appear, among them: how to equalize the market, in terms of daytime visibility, considering newer and older vehicles together? How to improve visibility in older vehicles that were not designed with DRL? The answer maybe lies in the alternative usage of automotive headlamps. Among other facts, one luminous device for two functions can result in safety improvements without unexpected investments. Therefore, how can this technically be achieved? By CONTRAN 667, that has adopted North America references, including luminous devices according to FMVSS, it is possible to use a low beam or a high beam dimmed to a maximum 7000 cd. According to Brazilian Traffic Code (CTB), the usage of low beams turned on during the daytime is mandatory. Both references consider headlamps to guarantee visibility improvements, low beam as it is and – only for FMVSS – the high beam dimmed. In this second case this can be seen as problematic when we consider halogen technology, because its dimming process is perceptive, even to the naked eye.
The purpose of this article is to show how light source technology can differ in the dimming process. Based on LED and halogen headlamp evaluations and comparisons, results will be explored in order to clarify some impacts caused by a single technical criterion applied on devices with different technological levels.