I need a built-in display that doesn't require high brightness and resolution.

Interest in Head-Up Displays (HUDs) is rising as it has been reported that the compact SUV 'Kona,' scheduled to be unveiled by Hyundai Motor on the 13th, will be equipped with a combiner-type HUD. A combiner-type HUD is a form in which the HUD is installed separately in the vehicle rather than being built-in.

A HUD is a device that projects images such as the vehicle's current speed, fuel level, and navigation onto the windshield directly in front of the driver, minimizing the need for the driver to shift their gaze elsewhere while driving. It is a system that can prevent accidents caused by not looking ahead while operating a navigation system or using a smartphone, and is considered safer than an HDD (Head Down Display) because it can prevent blind spots.

Currently, the display panels used in HUDs are miniaturized versions of Silicon Liquid Crystal Displays (LCoS), MEMS Scanners, LCDs, and OLEDs. With the emergence of Micro LEDs, which have the advantages of high efficiency, transparency, and flexibility, attention is being paid to whether they will be applied to HUDs.

Replacing the panels currently used in HUDs with Micro LEDs can not only increase light efficiency, reliability, and lifespan but also enable sharper images with high brightness. Displays in automotive infotainment systems are increasingly incorporating high-resolution panels. Regarding the view that HUDs also require high resolution, CEO Moon of Eyedis stated, “People say that HUD displays need to be sharp, but that is not necessary. A display viewed while driving needs to be moderately bright. Since driving is the primary focus and the HUD should only play a supporting role, it does not need to be excessively bright or sharp.”

Micro LEDs embedded in vehicles have many advantages

HUD products currently on the market are not built into the vehicle but are purchased separately and installed. There are two main types: one that uses a transparent display, such as an LCD or OLED, mounted on the windshield to project virtual objects for the driver to view, and a laser method that applies a light-emitting material to the windshield and projects the image. The most commonly used method is the projection type, which consists of a light source for displaying information, an optical device for projection, and a transparent screen on which the information is projected. The device is placed on the dashboard and connected to a smartphone for use.

In applications requiring the attachment of additional reflective films or combiners, conventional LCDs or LCoS are sufficient without the need for Micro LEDs. However, if the future trend involves embedding HUDs into vehicle windshields, using standard LCDs becomes impractical due to the curvature of the glass, which causes distortion as it deviates from the center, and the large range of temperature fluctuations. CEO Moon explained that there is a possibility of resolving these issues by utilizing Micro LEDs through transfer technology.

To embed a HUD, issues with the panel or optical system must be resolved.

Regarding the rarity of built-in HUD products, it was stated that issues concerning not only the panel but also the optical system, controller, and interface must be resolved. Emphasizing the importance of experience in the optical system, it was stressed that to eliminate distortion or chromatic aberration, images should be laid out and managed in a coaxial manner during optical design, rather than attempting to find the optimal image using various mirrors.

In addition, he stated, “Since the car has two panes of glass, refraction occurs, resulting in a double image; it is necessary to find a solution to this problem,” adding, “There are also limitations for small and medium-sized enterprises in converting the combiner type to an integrated one.”