We all know that during the driving process, we need to look down at the speed, fuel consumption and other information on the dashboard from time to time, and the average time required for this small action is about 1-3 seconds. Taking the average speed of the urban road at 65 km/h, the attention is about 3 seconds away from the road, which is equivalent to driving 54 meters with closed eyes. In real life, there are countless traffic accidents caused by the driver's distraction.

However, you can't always look at the dashboard information when you drive. Yes, you can't watch it, but we can't look down! In this issue we introduce HUD car head-up display technology.

The origin of HUD car head-up display technology

The full name of HUD is Head Up Display, the head-up display, which was first used on military aircraft to reduce the frequency at which pilots need to look down at the meter. At first, HUD casts driving-related information on the pilot's helmet through the optical principle, so that the pilot can pay attention to the various indicators of the flight and receive the information transmitted by the ground while ensuring normal driving, thereby improving the safety and convenience of driving. Sex.

Since the 1980s, HUD has been grafted from cars to airplanes, but HUD has really caught the eye of the world or is widely understood in virtual display concepts. Google Glass has aroused the infinite imagination of augmented reality, HUD can be described as "the smart glasses belonging to the car." The projection image produced by the HUD application applied to the car is presented on the road instead of focusing on the interior of the car or the windshield. With this design, the focal length adjustment of the human eye is eliminated.

At the beginning of the design, the driving force of the HUD is the safety of driving, so that the driver does not need to transfer the line of sight to the dashboard or the central control during the driving process. Therefore, the information projected by the HUD is mainly the driving condition indicator of the automobile, such as the meter. The information on the speed and fuel volume displayed on the disc; further, the designer hopes to achieve the goal of intelligent driving through HUD, giving it more functions, including navigation, text messaging, telephone, mail, etc., even adding simple interaction to let the car Become a mobile terminal like a smartphone.

How HUD car head-up display technology works

The principle of HUD is similar to slide projection. The light information emitted by the projector is reflected by the "mirror" onto the "projecting mirror", and then reflected by the "projecting mirror" to the "windshield". The human eye sees the virtual image located at 2-2.5 meters in front of the eye, giving The human feeling is that information is suspended in the road ahead.

The position of the HUD image on the windshield is adjustable, and the key to this is the "projector". By changing the angle of the "projection mirror", the position of the HUD image can be adjusted.

The windshield is curved, and if the image is projected directly on the curved glass surface, the image will be deformed. This requires a corrective action - so the "projector" and "mirror" are designed to be curved.

Using the principle of optical reflection, HUD can display information such as overspeed warning, vehicle condition monitoring, fuel consumption, speed, and rear-end tracking on the windshield. It can focus the driver's attention on the road ahead and achieve active driving safety.

It projects the driving information to the front of the line of sight with the driver, avoiding the distraction of the road ahead due to the observation instrument, and reducing the delay and discomfort caused by the constant adjustment of the eye focal length. The height is at a similar height to the human eye's head-up line of view, so the image is imaged in the middle and lower parts of the windshield. The virtual image blends well with the road surface and is usually projected 1-2 meters in front of the car's hood.

In addition, today's HUD head-up display technology not only provides basic driving information of the vehicle, it can have high-precision navigation guidance and road information prompts, and can also send and receive WeChat, call, and song.

Imagine how many traffic accidents are caused by the driver looking down at the phone, and HUD just liberates your phone, and the security is greatly improved.

HUD car head-up display technology can display information

Current speed.

It is the most basic information of HUD. This information is especially important when the speed limit camera is everywhere on the city road, when driving at the highest speed limit or when the camera is decelerating.

Navigation information.

This is a very practical information, especially when there are many cars in the city and road navigation.

Red fault flag

A red fault light appears, which means that there is a big safety hazard when the car is turned on.

Driving assistance information

Such as speed limit display, active lane keeping information, cruise information, etc., when using the car's high technology and making adjustments, this information can be displayed on the HUD, so that the driver does not have to look down at the meter to adjust.

Advantages of HUD car head-up display technology

1. The HUD information display position is higher than the traditional combination meter position. That is to say, when the driver wants to view the vehicle information, the HUD only needs to lower the head by 5-10°; if the combination meter is used, it needs to be 20-25° lower.

2. When the driver views the driving information from the combination meter, the eyes are transferred from the road to the combination meter and then transferred to the road. Due to the high brightness of the road and the low brightness of the combination meter (inside the vehicle), the eyes will experience from bright to dark. During the bright process, the pupil of the eye will be adjusted; at the same time, the focus of the eye will be from far to near and far. When the driver looks at the information from the HUD, the eyes do not need to be so tossed.

The above two aspects are combined. The driver can reduce the time of line of sight transfer, the change of eye pupil caused by line of sight change, and the change of eye focus point. The final result is that the driver's line of sight and attention are less deviated from the road. Improve driving safety.

HUD car head-up display technology implementation

There are three main types of current HUD implementations:

1. Directly use the front windshield as a display

This kind of implementation is mostly a pre-installation scheme. The representative product is the virtual windshield HUD concept technology developed by Jaguar Land Rover in July 2014. It can display the interior parameters and driving routes directly on the windshield. Just like playing a real version of a GT car or Forza, the system can even show you the ghost car that you had previously on the same runway. And can control the various functions of the car with gestures.

2, through an additional display

This implementation is a post-installation solution. Nandy, launched in 2014, is the star product under this program.

3, using the front windshield reflection to achieve

This kind of scheme also belongs to the post-installation scheme. The product is mainly realized by the mobile phone APP, and realizes the HUD function by using the reflection of the mobile phone screen on the front windshield. Representative products include: Baidu map, map map, Gaode map, Navier HUD, aSmart HUD 3D, Awesome HUD and so on.

There are four main disadvantages to products that are reflected by the front windshield:

Poor sharpness: The images projected through the screen of the mobile phone are all based on the principle of physical reflection, which is more susceptible to the influence of light in the environment, and cannot be displayed under strong external light conditions;

Small amount of information: Since the mobile phone and the car are independent and do not achieve effective interconnection, the function information of the mobile phone itself can only be displayed and projected, and the original safe driving target of the HUD cannot be fulfilled;

The stereoscopic effect is poor: the projection of the mobile phone screen is far from the realism and stereoscopic effect of the HUD product compared with the imaging;

Poor adaptability: The mobile phone is placed on the instrument panel for projection for a long time, which is not conducive to heat dissipation and will cause damage to the mobile phone. At the same time, the energy consumption of the mobile phone projection is large, which will shorten the charging time of the mobile phone.

Therefore, the practical effect of the HUD mode implemented by the mobile phone software is poor, and more is just an attempt by a curious person, and can not truly satisfy the current positioning of the HUD function.

HUD car head-up display technology key points

1, imaging distance and display brightness is the key

The most important indicator for evaluating the HUD imaging effect is the imaging distance. The essence of HUD is to improve people's driving safety factor, which is to improve the driving intelligence and provide a new driving experience. Therefore, HUD imaging must be placed on the road, so that people do not need frequent focal length transformation. , read the information displayed.

2, followed by perspective issues

The viewing angle is limited by the display brightness. Due to the complex and varied environment of the car, the requirements for display brightness are high, both clear and not glaring.

3. Upgrade of imaging technology

The most basic HUD products are imaged by LED lights, which have lower cost but less flexibility and display effect. Subsequent micro-laser projection technology is gradually applied to HUD imaging, and there are obvious indicators on imaging distance and display brightness. improve. Laser projection technology is a major trend in terms of better achieving the functional goals of HUD.

Micro laser projection technology has experienced 3 generations since its appearance:

CRT, cathode ray tube, CRT flat-panel display has the advantages of large viewing angle, no dead pixels, high color reproduction, uniform chromaticity, adjustable multi-resolution mode, and extremely short response time. This type of imaging is less adaptable to ambient light and temperature changes and is not suitable for use in automobiles.

DLP, DLP technology refers to digital light processing technology, which means that this technology first digitally processes the image signal and then projects the light. At its core is a micromirror array. This state is determined by the data stored in the memory cells below the micromirror during operation. The micromirror surface is made of aluminum metal with very high reflectivity. When one beam of external light impinges on the micromirror, the two deflected states of the micromirror deflect the light reflection to different angles. However, this technique causes the RGB light overlapping effect to deteriorate under shaking conditions, which causes a more serious color change. Secondly, the DMD chip in DLP projection technology is easily affected by the controller and produces a dead pixel. Moreover, long-term use can cause gaps in the glass flake structure of the color wheel in the DLP, resulting in looseness of the color wheel. The emergence of various problems proves that DLP technology is not a long-term choice.

LCOS, LCOS is a liquid crystal on silicon, a matrix liquid crystal display device based on a reflective mode and very small in size. The matrix is ​​fabricated on a silicon chip using CMOS technology. The size of the pixel ranges from 7 microns to 20 microns. For millions of pixel resolutions, the device is only 1 inch in size. The data capacity presented by LCOS is much larger than the data capacity presented by DLP technology. The application of LCOS technology will have a positive effect on the improvement of HUD and will be more scientific and technological.

Key components of the HUD car head-up display

Projection unit

The projector unit integrates a projector, a mirror, a projection mirror, an adjustment motor and a control unit. The HUD control unit acquires information such as vehicle speed and navigation from the on-board data bus, and outputs an image on the projector.

windshield

Everyone may think, is this windshield special? Indeed, the left picture below shows the structure of the ordinary windshield sandwich. If the HUD image is projected onto the ordinary windshield, it is easy to form an image ghost and the projection effect is poor.

The PVB film inside the HUD windshield interlayer is wedge-shaped, that is, the glass is thick and thin, so that image ghosting is not formed.

It can also be seen from here that in order to reduce the cost of glass, the HUD system on most A and B-class cars will be equipped with a separate reflective glass. In most luxury brands, the cost limit is not so tight, and HUD will be used. windshield.

HUD car head-up display technology trends

3D HUD is the future

In September 2014, Toyota's California-based design team developed a 3D HUD display that enables 3D effects to be viewed by the naked eye. This development has made the HUD display more informative and intuitive. Compared with the popular flat display, the 3D effect can better match and combine real-time information and display based on the original intention of ensuring the driving safety of the HUD, thereby realizing the function of augmented reality. For example, the Toyota 3D HUD can also display the available parking lots nearby and estimate the time of arrival. At present, this system has been developed for 2 years. The main data comes from three sensors. The radar is responsible for collecting vehicle speed and position information, the camera captures road information, and the LiDAR sensor determines road objects or intersections.

Fully integrate OBD boxes with OBD information

OBD (On-Board Diagnostic) is the in-vehicle diagnostic system. Many HUD devices on the market now need to be connected to the OBD interface. Basic information such as fuel consumption, tire pressure and speed can be obtained from the OBD interface. This is also essential for HUD equipment. information. The OBD box currently on the market, as the basic equipment of the Internet of Vehicles, can collect vehicle data and analyze data through interaction with the cloud, and even some products can realize functions such as navigation and remote diagnosis.

However, HUD's requirement for displaying information content means that it also needs to obtain information through the OBD interface and process it. The core is also the OBD chip. All the data parsing methods are basically the same as the OBD box. With the diversified and intelligent requirements of HUD devices, it is inevitable to complete data analysis, positioning navigation, and network diagnostics in the background of the display. This also shows that HUD will fully function the entire OBD box. Compared with the OBD box, HUD is more intuitive in terms of data display, more technical and attractive, so the market is more open. Under such conditions that the market trend is gradually clear, many manufacturers of OBD boxes have begun the design and development of HUD products.

HUD car heads up to show the main problems facing the product

Although HUD's products are highly practical and have a bright future, the industry is still in its infancy. To achieve a leap from a novel device to a widely accepted product, it still needs to be improved in the following four aspects:

High hardware cost

A complete HUD device requires a strong backlight brightness, a focusable optical lens set, and high temperature resistant parts, all of which require high cost. For example, BMW's optional HUD will add more than 7,000 RMB, and Navdy will officially sell for 3,000 RMB ($499).

Poor interactive experience

The software and hardware of the vehicle HUD did not form corresponding standards and were in a chaotic stage. Like the speed data, some manufacturers get it through the OBD interface in the car, and some manufacturers get it through the mobile phone GPS.

The development of the function only stays in the reading of dashboard information plus navigation information. Not all In One solves the entire user's needs in the car.

The industry is in its infancy, there are no clear rules

Compared to the internationally standardized OBD, HUD is not a vehicle standardization, that is, for integrated design manufacturers, HUD is higher than OBD threshold. The development of HUD is as long as you buy a module that specializes in OBD manufacturers and embed it into HUD for 2 developments. The HUD has many structural thresholds and optical virtual image processing. It has no industry standards. No image processing technology from manufacturers has been enough as a standard in the industry.

Low market maturity

At present, most of the domestic civilian vehicle market is not equipped with HUD or just optional. There are also relatively few third-party HUD devices. Many people's understanding of HUD is limited to hearing about it. As with many intelligent hardware devices, the following problems are the same, and the imperfection of the product affects its market performance. The market is immature, there is no profit-driven, and the manufacturers have no incentive to improve their products.

HUD car head-up display technology future

1. Under the development trend of automobile intelligent network, HUD intelligent hardware has a good opportunity.

2. HUD is the most ideal way to make information display smarter and provide drivers with the information they need at the right time and place.

3. New technological advancements (including broader perspectives (FOV), augmented reality, higher contrast, and higher resolution) will result in a greater increase in the HUD experience.

4. The future HUD technology will deepen the integration with the assisted driving system and become an important part of the automatic driving technology.

5. Although the instrument panel with LCD screen may be more popular with the manufacturer, it may be replaced by HUD in the future. Tesla's upcoming model3 may replace the dashboard with HUD, making it the first car without a traditional dashboard.

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