Three types of in-vehicle HUD systems

There are three main types of automotive HUDs: Combiner-HUD (C-HUD), Windshield-HUD (W-HUD), and Augmented Reality HUD (AR-HUD).

（1） C-HUD

C-HUD is more widely used in the aftermarket. It will install a translucent resin plate above the car instrument and on the top of the dashboard, and then use the resin plate as a projection medium to reflect the virtual image. Usually, in order to improve the display effect, the resin plate will be specially processed, such as being made into a wedge shape to avoid imaging conditions such as reflection and ghosting. Compared with W-HUD and AR-HUD, C-HUD has lower costs, but has the following three disadvantages: small imaging area and limited display content; short imaging distance and low imaging height; it is arranged on the dashboard in front of the driver, which may cause secondary damage to the driver in the event of a vehicle collision.

（2） W-HUD

W-HUD is used for front-end installation, and there are currently multiple technical routes: magnified imaging based on curved reflectors, magnified imaging based on holographic optical elements (HOE), and magnified imaging based on holographic waveguides (Waveguide). At present, HOE and Waveguide technologies are not yet mature, and the main application is the magnified imaging technology based on curved reflectors. W-HUD uses the front windshield as an imaging medium to reflect imaging, which can support a larger imaging area and a longer projection distance. The disadvantage of W-HUD is that the windshield is usually a curved reflector, so W-HUD needs to be adapted with high precision according to the size and curvature of the windshield, which will result in relatively high costs.

（3）AR SKIN

The human-computer interaction design of AR-HUD must fully consider the needs of drivers at all stages of driving, as well as the relationship between the driver's attention range and time, so as to achieve a benign interaction with the driver. The so-called AR-HUD is the fusion of AR and head-up display. Although it is still the same as W-HUD, it uses the windshield as a projection medium to reflect the image, but the difference is that it will also combine the information displayed by the system with the environment outside the car. Using a fixed perspective of the real world, through various sensors installed on the vehicle, during the driving process of the vehicle, AR-HUD can sense the surrounding environment and collect relevant data, and perform multi-level processing such as identification, detection and tracking of static and dynamic objects. Combined with the map data of the navigator, it completes system operation and analysis, thereby ensuring the driver's safety, stability, convenience during driving, and the accuracy and scientificity of the information displayed by the system.