# High-Resolution Pixel LED Headlamps: Functional Requirement Analysis and Research Progress
## 3 Research Progress of High-Resolution Headlamps
### Existing Beam Diversity of High-Resolution Headlamps  
The CLS-class multi-beam headlamps of the Cedrus Mercedes-Benz have a total of 24 LEDs arranged in a grid pattern [53]. The LEDs have a light-emitting area of 0.5 mm\({}^{2}\). Each LED can emit a light flux of 90 lm. The gap in the LED package is closed by the main optical device to homogenize the LED light and project it onto the road. The gap of each LED can make its light spots just coincide, and the external geometric structure converges to achieve a higher level of overall system efficiency. The LEDs pass through a total reflection optical device made of a fiber-like silicone material. The light emitted by the LED passes through the external geometry of the fiber and aligns with the auxiliary lens. This fusion achieves a high overall system efficiency, which can produce 90 lx illumination output in 25 m with a pixel width of 1.2\({}^{\circ}\). The two modules produce more than 195 lx of lighting output and reach a high beam range of 485 m. The brightness gradient between full-power pixels and darkened pixels passes through the auxiliary lens surface, and the target microstructure is optimized, thus the overall adjustment has a significant mitigation effect. The light distribution is divided in vertical and horizontal directions, and it is more inclined than the 30\({}^{\circ}\) tilt observed in the conventional low beam module to use vertical or right-angle tilt. This tilt is produced by the grid distribution pattern. The anti-glare, as shown in Figure 8, is realized by turning off the light in the designated area, and the effect of adjusting the light in the area can be achieved. Matrix LED headlamps can save the head by illuminating only the body of the object with a lower lighting array, meaning that they can draw the driver's attention to danger without dazzling people or animals in front of the vehicle. [PERSON] et al. fabricated an m-LED pixel array based on a flip-chip structure [54]. The array uses a photosensitive polyimide core dielectric layer to form multi-level metallization. This structure allows each LED in the array to be independently controlled. The spacing between individual pixels is 115 \(\times\) 115 \(\upmu\)m, and there are a total of 256 LED pixels. Research  
Figure 8: Partial schematic diagram of multi-beam LED module with improved resolution. has found that, by reducing the pixel pitch to eliminate the dark area between pixels, it can be used as the light source of pixel car headlamps. [PERSON] et al. clarified that, for highly clear glare-free and road marking functions, a highly pixelated automotive headlight system should be adopted [55]. Among spatial light modulators and pixelated LED solutions, it is currently the most reliable and optically efficient solution. For example, the field of view of a good road marking is 15\({}^{\circ}\) horizontal and 10\({}^{\circ}\) vertical, and the required resolution is 0.1\({}^{\circ}\). In order to maintain good contrast, the light source needs at least 15,000 pixels. With a smaller number of pixels, this is achieved by changing the focal length of the optical system. Although the pixel resolution is low, road marking solutions with thousands of pixels provide good functionality. [PERSON] et al. pointed out through comparative experiments that, when 4 k pixels are used for headlamp design, the glare-free area can be finely adjusted without the potential interference projection of light and dark contrast lines, and it can maintain a long-distance lighting field of vision while being illuminated at high speeds [51]. The car light model can provide a resolution of 0.25 to 0.3\({}^{\circ}\) in two directions within a complete angle range, which is much higher than the resolution of the human eye, and each pixel of the entire model is very uniform. The size of the glare-free area corresponds to the parameters of the lighting module. The pixel edge blur is defined as the same angular distance between 0.5 k and half of the maximum intensity of the pixel.