Given the difficulty of selling first impressions, both good and bad, it is increasingly important for automakers to stay ahead of the curve when it comes to human-machine interface (HMI) displays. Organic Light Emitting Diode (OLED) display technology not only offers a way to ensure the best possible first impression but also provides real advantages for users and interior designers.
According to a recent report by the Korea Display Industry Association (KDIA), the global automotive display market is projected to experience a compound annual growth rate (CAGR) of 7.8%, rising from $8.86 billion in 2022 to approximately $12.63 billion in 2027 [1]. The adoption of OLED displays in vehicles is cited as one of the factors driving this growth. In 2022, OLEDs only accounted for a 2.8% market share, but this is expected to grow to 17.2% by 2027.
Let's look at the factors driving the growth of OLED display technology in automobiles.
OLED technology in car displays
Until recently, LCD (liquid crystal display) technology was the most widely used in automotive screens. This mature and well-established technology, originally from the consumer industry, has been adapted and approved for automotive applications.
The modern consumer industry, from smartphones to computer monitors and televisions, has already begun its transition to OLED display technology thanks to its high image quality and slim form factor, and the automotive industry is also adopting OLED technology for similar, sector-specific reasons. In fact, many of the intrinsic characteristics of OLED technology are very attractive for automotive display applications.
Pure black and high contrast:
Since OLED is an emissive display technology, when a pixel is off it emits no light, so the color black is "pure." In contrast, the operating principle of LCD technology is based on blocking the light from the backlight unit, which is why it generates a dark gray but not "pure black." LCD manufacturers try to overcome this obstacle by using a mini-LED array to implement local dimming and turn off the backlight in areas with black pixels. While this method improves contrast, it suffers from a lack of pixel granularity, which can produce unwanted effects such as the halo effect. Furthermore, the extra layer for the
mini-LED array and its electronic control adds thickness, weight, and cost to the system. These factors become even more significant as screen size increases.
So, what advantages does OLED display technology offer to car users?
• Most graphical user interfaces (GUIs) use a black background to avoid distracting the driver and passengers at night. Thanks to OLED's pure black characteristics, user comfort is greatly improved.
• High contrast increases screen readability and enhances overall car safety.
• Wide viewing angles ensure the screen is clearly visible from various positions within the vehicle.
• At low temperatures, OLED displays maintain their fast response time, unlike other technologies. The most important real-time information is clearly visible without delay, even early in the morning on a cold winter day.
• OLED protects the eyes because it does not need switched backlighting, thus reducing fatigue during long periods of time.
Interior design integration and reduced energy consumption:
OLED technology helps automakers overcome several challenges. With increasing screen size, OLED technology offers more advantages over LCD designs. OLED has fewer layers and a thinner structure, allowing automakers to introduce improvements in interior design such as:
• Lighter and thinner profile reduces the weight of larger displays.
• Smaller radius for designing curved displays and innovative bezels for a well-defined brand identity.
• With Pure Black technology, the display bezel can be integrated into the trim, providing a look and feel unique to the HMI module.
• Low power consumption, especially when the background image is dark.
• Environmentally friendly, using less plastic than LCD displays.
The low power consumption and lighter weight of large screens are especially advantageous for electric vehicle manufacturers, who can thus offer greater range with the same battery capacity.
OLED technology has been adapted to the requirements of the automobile
Car manufacturers and suppliers who remember the limitations of older OLED displays should take note. Screen burn-in caused by numerous (often unused) static icons in a car's GUI and brightness issues for readability in sunlight have been resolved with advancements in OLED technology.
With two-layer OLED technology, or tandem OLED structure, manufacturers have significantly increased screen brightness. In addition to the brightness, the organic layer added to the structure disperses energy within the OLEDs, increasing stability and lifespan. Vehicle manufacturers and their direct suppliers have recognized these advancements and are increasingly using OLED displays in high-end vehicles.
The Touchscreen Interface:
Regardless of the display technology, the touchscreen interface is fundamental to providing an excellent user experience. The requirements for a touchscreen in a vehicle are much more demanding than those for consumer devices. These are some of those requirements:
• Reliable operation under more variable environmental conditions.
• Operability with gloved fingers.
• Electromagnetic compatibility for immunity to noise and radio frequency emissions.
• Functional Safety (ISO 26262 ASIL-B) such as safety-critical mechanical buttons being converted into a virtual button on the touchscreen.
In recent years, most LCD manufacturers have integrated multi-touch functionality into their displays using "on-cell" or "in-cell" technologies. Since OLED technology uses a layer with a low-impedance cathode on top of the pixels, only an "on-cell" structure is used. As a result, all major automotive OLED manufacturers have developed, or are developing, this type of design because it allows for thinner, lighter, and more flexible touchscreen OLED displays.
Figure 1: Layers of an on-cell OLED touchscreen for automobiles. While the use of on-cell technology allows for thinner OLED displays, it also creates new challenges for the touchscreen controller. This occurs because the touch electrodes are closer to the cathode layer and the screen pixels (see Figure 1: Layers of an on-cell OLED touchscreen). In on-cell designs, the touch electrodes now have a higher capacitive charge relative to ground. Although the finger's touch capability remains unchanged, the sensitivity of the touch is degraded. Consider this example to visualize the difficulty: with older screen technology, detecting a finger's touch capability is like measuring the change in water levels when a glass is added to a small bucket. In contrast, with the thin on-cell OLED structure, the process is now comparable to measuring the same change in a full bathtub! Touch Controller: The electromagnetic noise generated by pixel switching, along with its stronger coupling to the touch electrodes, increases the risk of false or missed touch detection. These difficulties make it paramount to select a touchscreen controller technology that provides high signal detection capability relative to noise. (SNR). The touchscreen controller must incorporate: • Control and detection techniques adapted to the high load of the on-cell OLED touch sensor. • Powerful noise cancellation techniques. • Fast and efficient signal processing to achieve high touch detection rates and reduced first-touch latency. High-tech look and feel. The ability of OLED displays to deliver high-quality visuals, a pure black background, improved energy efficiency, and a lightweight, curved panel creates a final product that will appeal to modern buyers and positively influence their decisions. The touch experience must also be flawless for the user despite the technical challenges induced by the thin on-cell OLED technology in the car. Microchip's maXTouch® touchscreen controllers are not only based on proven technology for fast, accurate, and reliable multi-touch detection, even through gloves, but also offer excellent flexibility to match the aesthetics applied in automotive designs. The new M1 generation of touchscreen controllers maXTouch provides new control and detection mechanisms along with advanced signal processing to ensure fast, reliable, and safe touch operation on new automotive OLED displays. References [1] https://displaydaily.com/automotive-display-market-set-for-robust-growth-with-oleds-taking-center-stage/
