Nowadays, with all the places digital displays can be found, evidence indicates that it may not be that hip to be square. Displays that push the boundaries of the conventional rectangular, flat-panel design permit extremely organic incorporation of display features into shapes and sizes that are a far better fit with their use and context. Non-rectangular displays are also known as freeform displays (sometimes “free form” or “free-form”), which denotes their bespoke shapes and alludes to the design freedom that they bestow to device manufacturers.
Freeform displays initially obtained consumer attention with the introduction of circular displays. Some notable firsts include wearables such as the Android-Wear Moto 360 (originally launched in 2014) and Samsung Galaxy Watch (originally launched in 2018), and smart home devices such as Google’s Nest Thermostat (originally launched in 2011), which are far more multi-functional than their analog equivalents. Circular designs represent ideal digital substitutes for buttons, dials and knobs, enhancing the conventional user experience with augmented visual performance, touch controls, and next-gen design that introduces a feeling of luxury to classic commodities.
Android-Wear Moto 360 smart watch (left; Source: Amazon.com), Samsung Galaxy Watch (middle; Source: Samsung.com), and Google Nest Thermostat (right; Source: Google.com).
One commercial sector that rapidly exploited the advantages offered for organic display integration by freeform displays was the automotive industry. Although original concepts for automotive design are regularly seen in the showroom, the overall form factor of a passenger vehicle (from its framework to the configuration of its interior components) is reasonably established. This is a consequence of both roadway safety standards and consumer expectations regarding the location of the gear shift, steering wheel and speedometer. As a result, displays that can embrace any shape to accommodate a more restrictive layout offer opportunities for novel display-based automotive systems.
In-vehicle displays have typically been located in the center console, relaying digital information for navigation, infotainment and now-mandatory back-up-camera systems. Such rectangular displays have been restricted to the available space of the car interior to not encroach on other important components.
A traditional center-console display used for navigation, infotainment, and rear visibility via back-up camera systems.
Rectangles are especially inconvenient in other sections of the vehicle, such as the particularly space- and shape-restrictive speedometer area. This obstacle has supported the longevity of analog components in this region of the vehicle, with numerous new vehicles still utilizing analog dashboard designs.
A backlit analog speedometer region (left) and a rectangular display-based speedometer (right).
A freeform display-based speedometer offers nearly unlimited freedom in design and new space-saving approaches. At the very least, the freeform display can replicate the shape of traditional speedometer panels.
Automakers seeking to substitute analog components in the car interior for digital equivalents are paying meticulous attention to the ease with which a display can occupy the space of conventional interiors. Novel freeform displays allow designers to enhance the display space within conventional vehicle designs (over rectangular flat panel display integrations) while simultaneously supplying augmented features and user experience.
Display maker Sharp was among the earliest to demonstrate a selection of cutting-edge automotive freeform designs, comprising completely circular, dome-shaped, and bespoke displays from its booth at CES 2015. These early concepts, which applied new LCD-TFT (IGZO) technology, have inspired numerous further display makers to think about how the shape of displays can shape the future of the automotive interior.
Sharp freeform displays at CES 2015. (Source: CNET.com)
Additional images from the Sharp CES 2015 showcase can be seen on Engadget.com.
Technology Enabling Freeform Displays
Overwhelmingly, automotive freeform displays are underpinned by LCD (liquid crystal display) technology. For anyone with any experience of LCD technology, this might appear counter-intuitive because numerous layers constitute an LCD display panel (polarizing filter films, glass substrate, liquid crystal layer, TFT backplane, backlight or reflector). Each layer requires cutting or shaping in an identical freeform pattern to generate a singular LCD display.
Illustration of layers in an LCD display.
Nevertheless, the low expense of LCD components and LCD’s long-standing advantages in automotive display integration (durability, longevity and performance) render a freeform LCD a satisfactory solution for several automakers, even when balanced by its more complex process of cutting and assembly. Moreover, higher display production costs are likely worth the returns, as vehicles bolstered by cutting-edge freeform panels will certainly appeal to contemporary consumers.
An additional challenge associated with the use of LCDs is the conventional placement of LCD electronics (namely an LCD’s “gate driver,” which is an integrated circuit driving current to activate pixels in the display). Sharp elaborated on this concern in a June 18, 2014 press release in respect of its new freeform display concepts.
“Conventional displays are rectangular because they require a minimal width for the bezel to accommodate the drive circuit, called the gate driver, around the perimeter of the screen’s display area. With the Free-Form Display, the gate driver’s function is dispersed throughout the pixels on the display area. This allows the bezel to be shrunk considerably, and it gives the freedom to design the LCD to match whatever shape the display area of the screen needs to be.”1
Essentially, novel technologies are allowing the gate driver electronics of the LCD to move from the bezel—which supplies a row/column distribution of light-driving power to every pixel along that column or row—to the active display area immediately behind the pixels, driving power to each pixel in a far more direct and dynamic manner. These electronics undergo integration with the display’s thin-film transistor (TFT) layer in several configurations in accordance with the proposed display shape.
Traditional displays require a rectangular shape and minimum bezel width to accommodate gate drivers on the edge of the display. (Image Source: Sharpsma.com)
By moving circuitry out of the bezel and into the active area of the display, the bezel is freed from design constraints and the display can be cut into virtually any shape. (Image Source: Sharpsma.com)
What meaning can we take from this? With power sent to the display at any point, display makers can cut display layers into any shape without restricting that power. Consequently, LCDs continue to represent solid contenders for freeform display design. Designers have been liberated from conventional rectangular configurations and can keep relying on the advantages of LCD displays for automotive integrations: tested processes and materials that guarantee display durability, longevity and performance.
What About OLEDs?
With all the attention surrounding OLED flexibility, it might be assumed (correctly) that OLED technology would easily permit the customized shapes of freeform displays. Additionally, flexible OLEDs have been commercially available for as long as freeform displays (refer to early flexible OLED devices like the Samsung Galaxy Round and LG G Flex, both launched in 2013).
Although OLEDs offer ideal device flexibility (this is because, contrary to LCDs, they do not need a backlight), the defining feature of a freeform display is its shape, rather than its curvature (at least for now, curved and flexible displays take up their category). Consequently, the flexibility provided by OLED is not strictly needed for freeform display design—and in some instances, it is not even the preferred option.
LG demonstrates the flexibility of its 18-inch OLED panel. (Source: LG Display)
OLED embodies an array of benefits to display performance that render it a prized technology among contemporary automotive designers. These advantages comprise enhanced contrast for increased visibility in ambient light conditions, elevated dynamic range, augmented brightness consistency, improved response times, and a reduction of display layers in comparison to LCDs. This might help to reduce several defects that are caused by layering, such as light leakage on display edges and/or mura across the display.
However, despite its highly appealing advantages, OLEDs might not match the performance needs of several in-vehicle displays. This is because the displays that are most essential for vehicle operation—comprising speedometer displays or center console control panels (any primary display-based Human-Machine Interface, or HMI)—are always active during vehicle operation. Such displays are subject to numerous power cycles whenever the vehicle is started or powered down, and need to maintain performance with constant usage throughout the vehicle’s lifespan. Automotive-grade displays in these installations necessitate levels of durability, environmental stability and longevity that are not presently provided by OLED technology.
Industry standards for automotive components (IATF 16949 and AEC-Q100 & AEC-Q200)2 are intended to test a car’s electronics rigorously and comprise tests for component durability and longevity by failure rates in an array of scenarios. For instance, regulated environmental durability testing might expose components to temperature cycling at extremes ranging from -40° to 125 °C.
Moreover, as cars last far longer than consumer electronics, manufacturers usually need to guarantee component supply and lifetimes up to at least five years, which can be extended to ten years by vehicle warranties.
The same problems are prohibiting a broad embrace of OLED technology among automotive displays. These include the short lifespan of blue OLEDs (about 14,000 hours3, with LCD lifetime usually between 25-40,000 hours4), screen burn-in issues, material and production expenses, and vulnerability to damage from temperature, water and additional environmental elements that a vehicle will experience. In a primary display HMI for a passenger vehicle, these represent untenable risks if performance loss impacts on vehicle functionality. In alternative integrations, where displays are not being constantly or critically utilized, the downsides of OLED might not prohibit their usage.
A notable exception: Audi will launch the 2019 e-tron with optional freeform OLED displays by Samsung.5 This displays will take the place of traditional side-view mirrors (in countries where regulations permit it). Has Samsung cracked the OLED-in-automotive code? (Image Source: GreenCarReports.com)
For instance, OLED is powering the next surge of decorative vehicle lighting. As a result of OLED’s flexibility, its manufacture can occur in an array of shapes and sizes, including rows of small OLED panels in taillights to produce state-of-the-art designs, OLED light strips along the vehicle interior to enable brighter ambient colors and color control, and many more examples.
Moreover, because they are principally decorative, the performance concerns of OLED are not prohibitive for lighting design. Indeed, the advantages of OLED for this category of the application easily outweigh the expense, yielding lightweight, power-efficient systems that can be dynamically controlled to generate particularly unique decorative lighting designs.
OLED concept lighting designed by BMW for the M4. (Source: BMW)
In terms of displays, although OLED concepts are clearly on the rise, there remains a noticeably low number of automotive OEMS integrating OLED technology into production vehicles, and certainly not as the primary display HMI. At this stage, the technology lacks the robustness to permit road-worthy OLED systems. It is more probable that automakers will carry on looking towards new LCD technologies and, as they gain traction, microLED displays to keep fueling their freeform goals.
Ensuring Visual Quality & Performance of Freeform Displays
Every display endures a certain degree of manufacturing and mechanical stress throughout production and installation. As LCD layers are integrated during production, air, particles and additional elements can be introduced between layers, leading to non-uniform bonding and visual quality problems that present as uneven sections of the display, known as mura.
Further stresses comprise bending, pinching, or pressure on a display panel during manufacture or following integration into an assembly. This can lead to similar defects in addition to light leakage around the display edges, visible non-uniformity, or dead pixels and lines.
These problems are compounded as the more exacting approaches for freeform display manufacture are implemented, such as cutting materials into non-standard shapes and inserting these display modules into non-standard integration spaces. As previously mentioned, visual performance is a critical factor in the extent to which a display is viable for automotive usage. Whenever displays function badly as a result of defects or embody low visibility as a result of color, contrast or uniformity issues, the functionality of key display-based HMI in the vehicle might be impacted.
The problem is that conventional display test methodologies utilized for measuring the visual quality of displays were conceived for the properties of classic rectangular displays. Particularly in respect of the analysis of spatially dependent qualities such as contrast, uniformity, and mura (random bright or dark areas across the display), the shape of the display needs to be accounted for to guarantee that every area of the display is measured.
Utilizing photometric imaging systems among visual display tests, there has always been a comfortable match between the rectangular shape of the display and the rectangular shape of the imaging system’s CCD sensor. Processing the image of such a display to guarantee precise quantification across the active display area is reasonably simple – typically a crop and rotation in accordance with the display’s four corners, which are aligned with the row/column layout of pixels in the rectangular CCD.
Radiant Vision Systems TrueTest™ Software includes a RADA (Register Active Display Area) feature that automatically locates a rectangular display’s corners, and the rotates and crops the image to isolate the active area of the display for accurate measurement.
However, in respect of a freeform display, isolating the display’s active area is a little more complex. There are not always corners on a freeform display that assist in defining its shape, while there might also be more than four corners. To tackle this, Radiant’s TrueTest Software also provides an image processing component such as RADA (although this is not just for rectangles). It enables the software to disregard any section of the image that are visible outside the active display area. This feature allows the user to crop out negative areas around freeform shapes in addition to dark (inactive) areas of a display that are visible beyond a non-rectangular bezel.
This proprietary feature, known as RIDA (Register Inside Display Area), identifies the would-be corners of a rectangular display area utilizing a test image. The software subsequently zeros-out the inactive area, focusing specifically on the active display area for quantification. Following the application of this image processing, the software analyses can establish particularly precise values for spatially significant qualities of the display—such as contrast, mura and uniformity—that necessitate evaluation, all the way to the display’s edges, irrespective of their straightness or roundness.
Radiant’s TrueTest Software applies RIDA (Register Inside Display Area) to freeform displays to enable testing on only the active display, regardless of non-rectangular shape.
Radiant’s TrueTest Software and ProMetric® I Imaging Colorimeters were recently showcased at the Society for Information Display (SID) Display Week 2019 exhibition in May 2019. At Radiant’s booth, there was a demonstration of a stadium-shape display (also known as a “discorectangle”), which was registered in software utilizing RIDA and analyzed for several defects with the use of an automated text sequence.
Radiant’s freeform display measurement demo from Display Week 2019, featuring TrueTest Software, a ProMetric I16 (16 megapixel) Imaging Colorimeter, and a stadium-shape display.
Measurement image shown in TrueTest Software before registration of a stadium-shape display.
Following registration of the freeform display (isolating only the central shape of the active display area), analyses can be undertaken in TrueTest with complete precision. In this instance, several tests were implemented in succession utilizing an automated test sequence (ANSI Brightness, Line Defects, Edge Mura, ANSI Color Uniformity (RGB), Checkerboard Contrast, Particle Defects, and Black Mura Gradient).
Freeform display measurement features such as RIDA, as well as additional key tests for in-vehicle display analysis such as Uniformity, Contrast, and Black Mura Gradient analyses, are available with the new TrueTest Software module, TT-AutomotiveDisplay™. This module offers all the advantages of TrueTest Software to effectively implement color, light and mura measurements using specific tests for evaluating unique qualities of displays integrated in vehicle exteriors. Find out more about TT-AutomotiveDisplay in the product Specification Sheet.
The Next Phase of Automotive Displays
What occurs when freeform displays are elevated to the next level? New shapes interact with curved components to generate displays of virtually all shapes and in all three dimensions. Flexible and curved displays permit automakers to totally revitalize the 3D architecture of the automotive interior and re-conceptualize the role of the display as adaptive to all surfaces in the vehicle.
Byton’s concept car premiered at CES 2019 with a 49-inch freeform display screen that spans the width of the windshield. The design also features curved touch displays in the steering wheel and a freeform center console display. (Source: The Verge)
While they are particularly freeform, curved displays also take up their own category, much like flexible and foldable displays. As they occupy their own distinct category, they also deserve their own review, the publication of which will be saved for a later date.
Produced from materials originally authored by Shaina Warner from Radiant Vision Systems.
References and Further Reading
- Sharp. (2014, June 18). Sharp Develops Free-Form Display, Enables Vastly Greater Design Freedom for Displays [Press Release]. Retrieved from http://www.sharp-world.com/corporate/news/140618.html
- Beasley, H. (2018, January 18). Automotive Quality Standards 101: What Qualification Really Gets You [Blog]. Retrieved from https://www.qorvo.com/design-hub/blog/automotive-quality-standards-101-what-qualification-really-gets-you
- Dhoble, S. J., Swart, H., & Kalyani, N. T. (2017). Principles and Applications of Organic Light Emitting Diodes (OLEDs). Cambridge: Elsevier Science & Technology.
- OLED. (n.d.). In Wikipedia. Retrieved August 20, 2019, from https://en.m.wikipedia.org/wiki/OLED
- Samsung Display. (2018, October 2). Samsung’s 7-inch OLED Display Selected for the Audi e-tron ― Audi’s First All-electric Vehicle [Press Release]. Retrieved from https://www.businesswire.com/news/home/20181002006155/en/Samsung%E2%80%99s-7-inch-OLED-Display-Selected-Audi-e-tron
This information has been sourced, reviewed and adapted from materials provided by Radiant Vision Systems.
For more information on this source, please visit Radiant Vision Systems.