# High-Resolution Pixel LED Headlamps: Functional Requirement Analysis and Research Progress
## 2 Functional Requirement Analysis
### Variety of Beams for High-Resolution Headlamps  
In addition to meeting basic lighting requirements, high-resolution LED pixel headlamps also provide advantages for all lighting functions with their controllable light distribution. Projection is the most common function. With the continuous development of high-resolution headlamps, the patterns projected are also constantly diversified. Far- and near-road lighting are the most common forms. At present, some basic projections have been developed, such as left- and right-turn arrow indications, pedestrian yielding, danger indications, and brand display. Figure 1a shows the attention bicycle lighting function, which was designed to remind the driver to pay attention to the bicycle ahead and drive carefully. The lighting function is being transformed into new style possibilities and safety functions through high-definition technology functions. Figure 1: (**a**) “Attention bicycle” icon. (**b**) “Attention pedestrian” icon for high-resolution headlamps. [PERSON] et al. divided the road planning projections of high-resolution LED pixel headlamps into two groups [9]. The first group is information and warnings for drivers, such as obstacle warnings, speed limit reminders, and real-time navigation information. As shown in Figure 1b, this lighting function can prompt pedestrians on the zebra crossing to go first. The second group is assisted driving, for example, indicating the width of the construction road. [PERSON] et al. divided the lighting styles of high-resolution LED pixel headlamps into six categories [10]. The first category is welcome and farewell lights, whose purpose is to impress people; the second category is non-glare high beam lights, which are designed to reduce the shadow area around oncoming traffic participants to improve driving safety, as shown in Figure 2a; the third type is the optical lane assist system, which estimates the width of the vehicle and warns other road participants to reduce steering wheel adjustment and reduce driving; the fourth type is dynamic, which aims to enhance the understanding of light during night driving; the fifth type is reasonable light distribution, which aims to adapt to more complicated roads and the driving direction of vehicles; the sixth type is light distribution safety, such as variable lanes for bicycles and safe distance from neighboring cars, which is implemented to improve the safety of other road participants. According to [PERSON] et al., due to the re-planning of road construction at night, the radius of passing small bends causes safety hazards for drivers [11]. [PERSON] et al. analyzed the driving simulator data of 18 road participants in the construction area and found that the more obvious the notification system is [12], the more it helps to avoid rear-end collisions in the construction area. Smartphone reminders are limited and rely on the most common systems. As such, car headlamps are more helpful in providing drivers with reminders. [PERSON] et al. mentioned in their research that, in overtaking or poorly illuminated roads in the construction area [1], when there are huge obstacles on the front road, lane bend and traffic accidents are likely to occur. The lights in the construction area project, that is, two light stripes on the road to warn the driver of the width of the road, improve the safety and the comfort of the driver, as shown in Figure 2b and examined through experiments. About 80% of participating drivers thought it could guide them well. The direction of the high-resolution headlamps projected around the construction site makes it easier for the driver to manipulate the steering wheel [13], and the information projected by the high-resolution LED pixel headlamps on the road shortens the driver's reaction time to obstacles and the braking response time [14]. [PERSON] et al. also proposed a similar concept [15]. The light distribution is a kind of curved light, and the high-resolution LED pixel headlamp can specifically adapt to road surface, curvature, road crossing, and branching.