Flex for Real
The increasing reality of flexible technology was clear at Display Week 2014, where it appeared on the show floor, in the technical sessions, and as the
subject of its own Market Focus Conference. e-Paper also appeared in its largest format yet.
by Jenny Donelan
SOMEDAY, we are told, we will have electronic newspapers, maps, and other devices that fold up to fit into our pocket or purse. As with most technological advances, we will not get there overnight. We will not wake up tomorrow morning to read our pocket newspaper. Yet, there really are displays – at least prototypes – that roll up and keep working when rolled and unrolled. And there are a host of products and enabling materials such as films and substrates that are enabling the reality of flexibility. We did not have all that just a few years ago. Progress toward flexible displays is being made, and you could hear about it and see it at Display Week 2014.
Flexibility on the Floor
There were plenty of flexible displays on hand at the Display Week exhibition, and, this year, the majority were OLED-based. Flexibility is one area in which OLEDs shine, as contributing editor Alfred Poor points out in his OLED Display Week review in this issue. Poor was especially impressed by a 5-in. panel from AUO on the show floor. This display had high-definition resolution (1280 × 720 pixels) and was built on a plastic substrate with a thin-film barrier for encapsulation. This active-matrix panel was just 0.2 mm thick – equivalent to about two sheets of paper – and could be bent to a radius as small as 1 cm.
Curved OLEDs on the show floor included phones such as LG’s G Flex and Samsung Display’s Galaxy Round, and the very large, curved TVs from LG. These products are not meant to be rolled or flexed (although the G Flex does actually bend somewhat, which should help in terms of durability), but the fact that they were flexible enough to be manufactured in a curved format speaks to recent advances in flexible formats. Both phones won Display Industry Awards this year, and LG won both a DIA and a Best in Show for its OLED TV products. Samsung was showing not curved OLED TVs like it did last year, but curved LCD-based sets.
In the Zone
Display Week’s Innovation Zone, a special area of the show floor where start-ups and researchers can show forward-looking technology, had a couple of interesting flexible exhibits. One was DaeFlex, a family of products from Korean company Daetec, that is designed to meet flexible-display manufacturing challenges. Technologies shown in this year’s I-Zone included cast flexible transparent substrates, strippers, and washable coatings.
We took note of an OLED display created on a plastic substrate by Plastic Logic that was demonstrated in the I-Zone. This panel used an organic thin-film-transistor (TFT) backplane that had been printed on plastic film at temperatures below 100°C. This device was so flexible that it could be rolled around a pencil while continuing to operate. For a picture, check out Alfred Poor’s OLED review in this issue.
Flexible Displays Market Focus Conference
This year’s Display Week event featured a Market Focus Conference dedicated to flexible displays. The conference was co-sponsored by SID and the market research firm IHS and coordinated by Mark Fihn, publisher of the Veritas et Visus family of display-industry newsletters. Among the many presenters at this all-day event were Kent Displays, Industrial Technology Research Institute, the Holst Centre, FlexTech Alliance, Argus Insights, Corning Glass Technologies, E Ink, Bardsley Consulting, Plastic Logic, Canatu Oy, and IHS.
John Feland from Argus Insights in Los Gatos, CA, talked about emerging consumer trends in wearables and what that means for display makers. What users want, said Feland, is lower power to minimize “care and feeding,” great readability in full sunlight, a very flexible form factor, and rich color imagery – all for somewhat less than the cost of a Rolex. Manufacturers are not there yet in meeting those desires, but efforts toward the above winning combination will drive broader adoption as performance is perfected and the elusive “killer app” for wearables is developed.
Gerwin Gelinck from the Holst Centre in the Netherlands spoke about the many layers required for flexible OLED displays and the need for moisture barriers, heat resistance, and other features in many of these layers. Noting that flexible prototypes have been demonstrated for more than a decade, Gelinck pointed out that new materials and processes are still needed in order to make these flexible displays cost-effective for a wider variety of applications on a mass-production basis.
Technical Flex Topics
The Display Week technical symposium also covered flexible technology in depth, with sessions including Flexible OLEDs I and II, Flexible AMOLEDs I and II, one on Flexible TFTs, and other sessions on wearables and various flex-related topics. Among the many flexible-OLED-display papers, we took note of one in particular
from researchers at Semiconductor Energy Laboratory (SEL) in Japan, along with colleagues from Advanced Film Device and Nokia, who demonstrated a novel OLED display that could be folded in half and still function – even when folded. The prototype 7.9-in. display on a plastic substrate had a high-definition 1280 × 720 pixel resolution (249 ppi) and was folded to a radius of 2 mm for more than 100,000 times without defects appearing.
Roving Reporter Steve Sechrist (whose TV and 3-D review from Display Week also appears in this issue) noted the work in printed organic TFTs (OTFTs) reported by the Research Center for Organic Electronics at Yamagata University in Japan. Here, Shizuo Tokito and team showed a 30 × 30 pixel OTFT array using silver nanowire inks. In the paper, they discussed work using printed TFT arrays and ICs employing a “pseudo” CMOS inverter printed on plastic film. They claimed electron mobility of 2 cm2/V-sec and a delay time of 3.5 msec.
In addition to the above papers, Display Week this year offered a seminar entitled Flexible OLED Displays and Lighting Devices by Universal Display Corporation’s Ruiqing Ma. In all, if you had any interest in flexible technology – and if you are in the business of displays, you should – Display Week was the ideal place to catch a glimpse of what the future has to offer. •
E ink has become almost synonymous with e-Paper and, as usual, had a booth chockfull of cool e-Paper products, including watches, signs, e-Readers, and other items. This year was no different, and E Ink was also showing off a new 32-in. display (Fig. 1); its largest yet, created in partnership with Global Display Solutions (GDS), a developer of outdoor and indoor digital-signage applications.
The new display is targeted primarily at applications in the digital-signage and information-kiosk markets and is available in black and white and color (E Ink’s Triton) modules. This is obviously a great application for the E Ink technology, as it enables signs that are lightweight, low power, and readable in ambient light
Fig. 1: E Ink’s new 32-in. electrophoretic display comes in gray scale (shown here) and color and is designed for indoor and outdoor signage.