Automotive Displays Proliferate at Display Week
The vehicles of our near future will use unprecedented numbers of displays, in form factors, materials, and sizes we are only beginning to discover.
by Karlheinz Blankenbach
Automotive displays are on the rise – not only in terms of mass production but in size, resolution, and overall capabilities. Automotive displays represent a steadily growing market, which is projected to reach 5 percent share of the worldwide display market over the next several years. It’s no wonder that this market evolution is having an impact on SID’s Display Week (Fig. 1)! This article provides a brief overview of automotive-related content presented at the symposium and a look at selected automotive displays shown at the exhibition during the 2017 event held in Los Angeles.
Fig. 1: Asahi Glass Company’s booth at Display Week 2017 exemplified a trend toward automotive-related exhibits at the show in recent years. All photos courtesy Karlheinz Blankenbach.
The Display Week symposium traditionally starts with keynote addresses from three industry luminaries. This year, one of the speakers was Sanjay Dhawan, president of the connected services division of Harman, who spoke on “Humanizing the Autonomous Car Experience.” Dhawan predicted that autonomous driving will transform the car from a place where the driver primarily performs the task of driving into a place for both leisure and work. Displays and advanced human-machine interfaces (HMIs), in combination with connectivity, will play a major role in that transformation. Within the symposium, six sessions (two of them joint sessions) were dedicated to automotive topics. Here is a brief summary of the ideas and themes presented in those sessions.
• Quantum dots are being used to enhance the gamut of automotive LCDs and are key to enabling an outstanding HMI experience. A display with a large color gamut will appear less “bleached out” by ambient light reflections than will a low-gamut display. However, quantum-dot technology has to improve in terms of lifetime and temperature range in order to meet automotive display requirements.
• Automotive-grade OLEDs with larger lifetimes and higher temperature endurance are paving the way toward series production.
• Curved, flexible, and freeform automotive displays are requiring dedicated technical solutions and new measurement methods. These displays enable new interior design visions and greater control over ergonomics.
• Reflection reduction methods and measurements including low sparkle are essential for bright ambient light use such as in convertibles or any open-top vehicle.
• Head-up displays (HUDs) provide ergonomic benefits. A 3D HUD was presented by Philippe Coni from THALES, France, in the distinguished paper, “Development of a 3D HUD Using a Tunable Bandpass Filter for Wavelength Multiplexing.” Related talks discussed improvements in picture-generating units like liquid-crystal-on-silicon (LCOS), as well as multi-depth approaches.
• The HMI within an automobile is becoming more important, with increasing numbers of displays and fewer knobs and pushbuttons providing the means by which drivers and passengers select functions related to climate, entertainment, lighting, etc. User interaction topics include multimodalities such as haptic feedback.
• Automotive interior lighting will see hundreds of RGB LEDs in premium cars in the near future. A new approach to overcoming the challenges involved in incorporating them was described in a paper by Robert Isele of BMW, in which RGB LEDs were equipped with intelligent drivers in the same housing, providing temperature and aging compensation as well as data connectivity. (For more on this topic, see “Automotive Interior Lighting Evolves with LEDs” in the May/June 2017 issue of Information Display.) The distinguished student paper from Christiane Reinert-Weiss and co-authors at the University of Stuttgart, “Development of Active-Matrix LCD for Use in High-Resolution Adaptive Headlights,” described the development and benefits of a 30,000-pixel AMLCD that modulates the frontlight to avoid bothering oncoming traffic. The prototype for this development was exhibited in the I-Zone and received the Best Prototype Award for 2017.
Three other presentations on automotive topics by the author of this article and Dr. Thomas Fink of Porsche included the address, “Automotive Display Measurements – Challenges and Solutions,” during the International Committee for Display Metrology (ICDM) workshop on Sunday; another talk on “Automotive Displays” for a Monday Seminar; and the automotive sessions keynote. Last but not least, Display Supply Chain Consultants (DSCC) organized a well-attended market focus conference on automotive displays – “Safety, Utility, Ubiquity” – that took place on Tuesday, May 23.
On the Show Floor
As in the technical program, the impact of automotive topics is increasing on the exhibition floor, from innovations in LCDs, OLEDs, HUDs, materials, and measurements to new approaches on the horizon like microLEDs. The latter promises luminance in the 10,000 candelas-per-square-meter (cd/m2) range with high efficiency, making microLEDs quite suitable for automotive applications. Unlike with consumer displays, the race for automotive display size is not over. However, 12.3-in. panels with 1,920 × 720 pixels are becoming a standard for larger-sized automotive displays. Raising image quality through larger color gamuts (as is happening for consumer displays), low reflectance (through films and optical bonding), integrated touch, curved and flexible displays, longer lifetimes for OLEDs, and reduced low-temperature response times for LCDs were among the many features showcased by different companies at Display Week. The rest of this article provides selected highlights from the exhibition.
The vast majority of today’s automotive high-resolution displays are thin-film transistor (TFT) LCDs. One trend involving this technology is seamless integration, which favors freeform displays like that shown in (Fig. 2) from AUO.
Fig. 2: The wide color gamut and 1.5-mm bezel featured in this 12.3-in. freeform dashboard LCD from AUO represent two major trends in LCD automotive panels.
This example highlights two other sought-after features in automotive displays: narrow borders and large color gamuts for high-quality HMI visualization.
Sought-after reductions in power consumption for automotive displays are necessary for fuel and electrical energy savings, but the high luminance required from automotive displays draws a lot of power. Another severe and costly task for integration is sophisticated heat management, so power reduction helps quite a bit. This can be achieved for LED-backlit LCDs, for example, by using local dimming methods (similar to those in high-end TV sets) as shown in (Fig. 3).
Fig. 3: These 12.3-in. LCDs from Tianma are shown with local dimming (top) for power savings and without local dimming (bottom).
Compared to typical movie content, the average automotive HMI content promotes lower gray levels and brightly highlighted characters, requiring more sophisticated dimming methods that are more difficult to measure. This issue can be overcome by using OLEDs like those in (Fig. 4) in the display from AUO. Only the lit pixels draw electrical power (similar to the way “always-on” displays work in OLED-based smartphones). As an example, the content of Fig. 4 can be visualized on an OLED at about 15 percent the energy usage of a comparable LCD.
Fig. 4: This 12.3-in. OLED display with 600 cd/m² was shown by AUO.
Most of the showcased automotive LCDs featured a white luminance in the range of 1,000 cd/m2, while the values for OLEDs reached 500 to 600 cd/m2, which enables an automotive-compatible lifetime.
Another big trend is a large-area, glass-covered dashboard. Corning showcased an all-glass prototype for the entire dashboard, including the center console. A seamless dashboard shown by AUO was built with two 12.3-in. LCDs, resulting in an impressive 27-in. panoramic display (Fig. 5). Such an approach, using optical bonding, is already in mass production at Mercedes.
Fig. 5: AUO’s dual-LCD panoramic dashboard consists of two 12.3-in. panels that are seamlessly connected.
A major requirement for non-autonomous driving is the fast and secure capture of driver-relevant information on the instrument cluster. Autostereoscopic 3D displays (beside HUDs) help a lot in this regard, but lack quality in terms of sharpness and eye-box sensitivity. Note that issues with autostereoscopic displays like convergence and depth-perception confusion are more likely to occur with prolonged (greater than 15 minutes) viewing. Most users will glance at these displays for only a second or two. A multilayer display (MLD) as showcased by LG in Fig. 6 (bottom) provides quick information gathering, even for “overloaded” instrument cluster HMIs.
An MLD consists of a rear display with high luminance (such as an LCD) and a (highly) transparent display (such as an OLED). The content, however, has to be optimized for this arrangement with software such as that currently being developed by Delphi. A transparent OLED (60 percent, Fig. 6 top) can be used as well for a direct-view HUD; both luminance and transparency must be high. A transparency of 70 percent is required in many countries for displays placed within the driver’s viewing area.
Fig. 6: This 3D instrument cluster from LG combines a transparent head-up display (top) — which is a 12.3-in. OLED (60 percent transparency and 600 cd/m2) with a multilayer display (MLD) at bottom, which uses both a transparent OLED and LCD with 1,060 cd/m2.
Another trend in automotive displays is replacing rear-view exterior mirrors with cameras and displays, as shown in Fig. 7 with a cockpit display from JDI.
Fig. 7: This cockpit display from JDI was built with 10-in. LCDs with a resolution of 2,880 × 1,080 (308 ppi) and a standard field of view (FOV) HUD.
The 10-in. LCDs have 308 ppi, which is about 50 percent higher than today’s high-end automotive instrument cluster displays. Above this impressive dashboard is a HUD, which is the size of today’s standard with a field of view (FOV) of about 8° by 4°. For augmented reality applications, the FOV for HUDs has to be significantly larger – 30° × 15°, which requires more than 20 times the optical – and by consequence, electrical – power. There were some holographic HUDs (such as from Luminit) exhibited, but capturing their images on pictures was difficult on the show floor. (For more about automotive HUDs at Display Week, see “The Expanding Vision of Head-Up Displays“ by Steve Sechrist.)
As there are generally no large, flat surfaces in car interiors, is it logical that curved displays are becoming more popular. Compared to mobile foldable displays, the radius for automotive large-sized displays can be in the range of hundreds of mm. Touch functionality (large size and curved) is a must for design-driven center stacks. This was demonstrated by BOE’s 15.6-in. LCD (Fig. 8) with 1,000-mm radius and 1,000 cd/m2. A brighter display showcased by JDI (Fig. 9) was an S-shaped 12.3-in. panel with a radius of 800 mm.
Fig. 8: A 15.6-in. curved (R = 1,000 mm) FHD LCD shown by BOE featured 1,000 cd/m2 and in-cell touch.
Fig. 9: This S-shaped 12.3-in. LCD from JDI was capable of 1,150 cd/m2 and had a radius of 800 mm for each curvature.
Besides automotive displays, there were a lot of automotive-relevant subassemblies, materials, and improvements at the show. The following areas were of particular interest:
• Bright ambient light imposes significant challenges on automotive instrument cluster displays, especially as it relates to readability of critical data such as speed or RPMs. At Display Week, Dai Nippon Printing (DNP) was promoting a display front film with just 0.1 percent reflectance (and a high transmission of 96 percent), which is about one tenth of standard reflection reduction methods. This improves readability significantly, by about one order of magnitude (assuming the contrast ratio as CR ≈ LDisplay / LReflected + 1).
• Many car functions are operated while driving, so especially for center stack displays, touch operation is best for both ergonomics and safety. Haptic feedback can be especially effective. Touch operation and larger panels, however, require scratch resistance. And one undesirable effect of anti-glare reflection reduction is “sparkling” for high-resolution displays. All these challenges can be met by the “haptic glass” from Sevasa shown at Display Week.
• Unlike consumer (aftermarket) displays, OEM displays have to withstand severe impacts – such as a person’s head hitting the display. Glass shattering is unacceptable. Corning showed a simulated head-impact-test video (Fig. 10) demonstrating how its convex and concave Gorilla Glass can successfully withstand major impacts.
Fig. 10: This screenshot is from a video of a simulated head-impact test from Corning based on its curved Gorilla Glass displays.
The above-mentioned presentations and exhibits represent only a modest selection of the huge variety of automotive technology featured at the Display Week 2017 symposium and exhibition. There will be much more to come in 2018, with additional auto-related content both in the technical programs and on the show floor. Looking forward, automotive displays will also be a focus of attention when (semi-)autonomous driving comes of age. Vehicle displays will then serve drivers from the standpoints of entertainment and occupation as well as driving information. •
Karlheinz Blankenbach has been a full professor at Pforzheim University since 1995. He is the founder of the university’s display lab. He holds an M.Sc. (diploma) in physics and a Ph.D. degree, both from the University of Ulm. He can be reached at firstname.lastname@example.org.