The automotive electronics race is in full swing. New technologies are being developed, while old ones are being optimized to provide consumers with the best electronic conveniences. One particular piece of technology that has gained notable traction over the last few years in the automotive market is Heads-Up Display (HUD).
Heads-up display is an automotive device that displays useful information (such as fuel gauge, speed, lane guidance etc.) on a combiner screen or the windshield of a vehicle, to ensure safe and informed driving experience for the driver. It is primarily designed to work with Advanced Driver Assistance Systems (ADAS), however, itcan also be interfaced with the driver’s smartphone if needed.
Many established automotive technology manufacturers have entered the HUD market, and many more are entering. If you’re a manufacturer of automotive electronics thinking about venturing into the product line, there are a few essential HUD design pointers that you might want to make note of. These pointers will help you design a high-quality automotive HUD product.
The backlight source of the picture generating unit
The picture generating unit (PGU) is the core component of an automotive HUD. It’s responsible for creating the digital image, which is then relayed, reflected and displayed on a glass screen with the help of a relay lens assembly.
A PGU is usually a liquid crystal display with LED backlight. Using a LCD with LED backlight ensures a slim compact HUD design, while also making the device energy efficient. The use of LED backlight is also crucial in terms of accomplishing optimum display brightness and dimming characteristics, both of which are vital features for an automotive HUD.
Glass screen shape consideration for combiner HUDs
If you’re designing a combiner HUD, make sure to design the glass screen in the shape of a wedge. This will prevent any ghosting issues, otherwise caused by the reflection from both sides of the glass screen. Furthermore, it will also help improve display effects and lower the overall cost of the product.
Contrast ratio recommendation
An automotive HUD has a strictly defined contrast ratio, typically in the range of 1.15 to 1.5.
HUDs with contrast ratios lower than 1.15 may produce undetectable images. On the other hand, HUDs designed with contrast ratios in the higher range may produce pictures that can be uncomfortable for viewing.
To assist in your contrast ratio calculations during the HUD design process, use the following equation:
HUD contrast ratio = (Ambient luminance + Display luminance) / (Ambient luminance)
Image brightness and dimmability
Perhaps the biggest challenge that automotive HUD manufacturers face when designing aHUD is accomplishing optimum brightness levels under all ambient light conditions. The device must be able to produce an image bright enough to be clearly seen on a sunny day, andmust also be able to dim the image so that it does not obscure the driver’s vision at night.
The luminous intensity of an HUD is specified by the light-emitting diodes (LEDs) that backlight its PGU. These LEDs are in turn controlled with a high-brightness (HB) LED driver circuit. When designing an automotive HUD, it’s recommended to choose the HB LED driver circuit principally based on its dimming capability, input voltage range andswitching frequency. Most modern HB LED driver circuits are capable of supporting wide dimming ratios which make them well suited for the challenge.
There are many other design considerations and specifications (not covered above) that are equally important and need to be kept in check when designing an automotive HUD. As always, if you need any further guidance, you can feel free to reach out and REVO will be happy to assist you.
REVO is a global supplier of high-performing industrial LCD display solutions. The company works with OEMs, contract manufacturers and independent electronic distributors, providing them with high quality displays and display kits for their specialty product design needs. For more details, please call 1-866-738-6797 or visit the company’s official website.