Three Dimensions Of Car Light Upgrade: Light Source, Technology And Function (III)

04 Functional upgrade route The third dimension of headlight upgrade is function. For consumers, the perceptibility of function is the strongest. Functions such as AFS, ADB, and projection have gradually become selling points for mid-to-high-end cars to attract consumers.
4.1. AFS AFS refers to Adaptive Front Lighting System, a front lighting device that provides light beams with different characteristics to automatically adapt to various usage conditions of low beam and high beam. AFS is designed for LED headlights, xenon lamps, and laser headlights. The original adaptive headlights only have longitudinal adjustment functions. By sensing the braking and acceleration actions of the front and rear axles, the headlights are adjusted longitudinally accordingly to keep the headlights stable. With the continuous development of technology, AFS has the function of switching between multiple modes such as curves, towns, villages, highways, and bad weather. AFS consists of four parts: sensors, electronic control units (ECUs), headlight control systems, and headlights. When working, sensors including angle sensors and speed sensors transmit signals to the ECU through the controller area network (CAN). After processing the data, the ECU outputs the headlight angle command to the headlight control system to make the headlight turn to the corresponding angle. Passenger cars equipped with AFS can achieve seven modes of lighting: rural road mode, highway mode, urban road mode, severe weather mode, headlight follow-up steering, instrument panel fault indication, and travel mode.
According to the monitoring data of Gaogong Intelligent Automobile Research Institute, the installation rate of LED headlights with AFS function as standard in the front-mounted passenger cars in the Chinese market (excluding imports and exports) in 2022 was 5.09%, and the delivery volume increased by 14.36% year-on-year.
4.2.ADBADB refers to Adaptive Driving Beam, which is an adaptive high-beam intelligent lighting system. It is a technology that can detect oncoming vehicles and adjust the irradiation angles of high beams and low beams accordingly to avoid oncoming vehicles from being disturbed by strong light. With the cooperation of the front camera, the system can control the light beam directed to the other car to be turned off when meeting, while the normal light beam responsible for lighting will not be affected in any way; after the meeting, the LED lamp beads that were turned off due to shielding will automatically turn on again to resume normal lighting work.
The ADB system is usually composed of a forward-looking active safety camera, a headlight controller, a light source module driver, a light source module, a transmission line, etc. At present, the main light source of ADB is LED, so the light source module driver is generally an LED driver module.
From the technical path of realizing the function of ADB, it can be divided into mechanical, matrix, DLP and other paths.
1) Mechanical. It has evolved on the basis of AFS technology and is mainly aimed at headlights using traditional light sources, such as halogen lamps or HID. The headlights are adjusted up and down or left and right by the motor, or the light type of the headlights is changed by rotating the shading plate. There are also ways to transform the original structure of the headlights, change the baffle to a variable light axis, and use the different shapes presented when the variable light axis rotates to block and adjust the high beam, so as to realize the function of adaptive high beam. The disadvantages are slow response and low precision.
2) Matrix. Matrix ADB uses multiple LEDs to arrange in a matrix and correspond to the illumination area one by one, and completes the light type change by controlling the brightness of the LED. The more LED light sources there are, the higher the resolution and accuracy of the adaptive high beam system. At present, most ADB headlights are matrix-designed, with 12 to 100 LEDs. Matrix ADB is better than mechanical ADB in terms of response speed and lighting effects. Due to the reliance on a large number of light sources, the requirements for optical system design are higher, and too many light sources also have higher requirements for system heat dissipation structure and control algorithm strategy.
3) DLP. Placing DMD devices in front of the light source to control the headlights can realize the projection function. The core components and technologies come from TI. 4) Other technical solutions such as LCD and μAFS are still under development.
According to the complexity of the function, the price range of an ADB headlight is mainly concentrated in the range of 1,200-2,500 yuan, and the high-end version is also close to 5,000 yuan, but the market penetration rate is low. Before 2018, the global penetration rate of ADB headlights was not high, and ADB was mainly installed on high-end models such as Audi A8 and Mercedes-Benz S-Class.
4.3. Projection The functions that can be achieved by digital projection lighting technology include: emitting two bright lines as wide as the vehicle to help the driver evaluate the driving route and passing ability; when the vehicle encounters pedestrians crossing the road, the headlights project a "zebra crossing" on the road ahead to remind pedestrians to cross the road safely; when the vehicle detects that the distance to the front vehicle is less than the safety value, the front vehicle collision alarm function is activated, and the headlights will project a white high-brightness prompt line to the road ahead of the driver's field of vision, gradually reducing to a high-frequency flashing warning, etc. In order to realize the projection function, there are many paths in the technical direction, including DLP, MicroLED, LCD, etc., but overall, the projection function is usually installed in high-end vehicles, and the penetration rate is slowly increasing from a low base.