Inspiration and Innovation Abound at Display Week’s Annual Technical Symposium
This year’s technical program at Display Week features more than 500 papers on topics ranging from quantum dots to light-field displays.
by Jenny Donelan
THE display industry is never static, and the annual SID International Symposium at Display Week both reflects and informs that state of constant change. Last year, backplane technology took center stage at the symposium, with 12 papers devoted to the topic of Oxide vs. LTPS TFTs alone. This year, backplanes remain an essential focus, but other topics, including materials that promise to disruptive the industry as we know it, are strongly represented. Program Chair Seonki Kim also points to an increased number of papers on vehicle displays and also displays being produced in curved and non-rectangular form factors.
This year, the technical symposium features 75 sessions and more than 460 papers. That’s more than any one person can take in during the four days (June 2–5) of the program, but you can take in a lot if you plan ahead by accessing the preliminary program online at http://displayweek.org/2015/Program/Symposium.aspx and also by reading this article, in which we point out some of the highlights.
Each year, the papers presented are organized by their major technical focus – Active-Matrix Devices, Applications, Applied Vision/Human Factors, Display Electronics, Display Manufacturing, Display Measurement, Display Systems, Emissive Displays, e-Paper and Flexible Displays, Liquid-Crystal Technology, OLEDs, Projection, and Touch and Interactivity – then assigned to sessions designated by topic, such as Wearable Display Systems. Each session consists of three to five 20-minute paper presentations. This year, four special focus areas – Oxide and LTPS TFTs, Wearable Displays, Disruptive Display Materials, and Curved and High-Resolution Displays – and three Mini-Symposia on Lighting [in cooperation with the Illuminating Engineering Society (IES)], Vehicle Displays and Trends, and Imaging Technologies and Applications were also included.
The peer-reviewed papers chosen for presentation at Display Week represent the best of the best. Here are just some of the highlights from this year’s sessions.
Display Week 2015 Symposium at a Glance
Display Week 2015 Overview
Quantum Dots and Other Disruptive Materials
Even if you can’t see quantum dots (QDs) – these tiny nanocrystals range from 2 to 10 nm (10–50 atoms) in diameter – they have been hard to miss lately. QDs are not new to the symposium or the exhibit hall at Display Week – companies such as 3M, Nanosys, and QD Vision have been named by SID’s awards committee several times since 2012 for their quantum-dot technology. Last year’s technical program featured three sessions dedicated to quantum dots, and, at the time, this magazine noted that the technology was gaining momentum. What’s new this year is that quantum dots are rapidly showing up in a whole range of LCD-based products, such as Amazon’s Kindle Fire tablets and in LCD TVs shown at CES last January. “It’s nice to see this technology moving from the experimental phase to the lab and now to product fruition,” says Qun “Frank” Yan, co-chair of the Emissive Displays subcommittee.
Quantum dots have many potential uses, as will be discovered in this year’s symposium, again offering three dedicated sessions on QDs. “Quantum dots have the potential to disrupt the display industry,” says Seth Coe-Sullivan of QD Vision, Vice-Chair of the Disruptive Display Materials special topic. Despite the aforementioned commercial forays, many of the improvements to the technology are still at the research stage, he says, adding: “The next question is: Can we reduce that science to practical innovations that lead to improved products?”
There is a great deal of interest in how QDs can help achieve Rec. 2020, the new ITU color specification for UHD broadcasting, says Coe-Sullivan. Jame Thielen of 3M will be presenting an overview of that effort in the paper “Optimizing Quantum-Dot LCD Systems to Achieve Rec. 2020 Color Performance.” Another recommended paper is “Next-Generation Display Technology: Quantum-Dot LEDs” from Jesse Manders of NanoPhotonica. The NanoPhotonica team achieved extremely high external quantum efficiency for green and blue quantum-dot LEDs, as well as high performance for red QD-LEDs.
Quantum dots are but one technology classified as disruptive by this year’s technical program organizers. Other technologies include new material innovations in LCDs and in OLEDs, according to Coe-Sullivan. “OLED is very materials-innovation heavy right now,” he says. One example is the invited paper, “Combinatorial Design of OLED-Emitting Materials,” by Alán Aspuru-Guzik of Harvard University, which looks at a particular example of recent developments in thermally assisted delayed fluorescence (TADF) emitters that are enabling novel classes of OLEDs using technology that may be better for the environment and, possibly, longer lasting than OLEDs using phosphor emitters. A representative paper on potentially disruptive LCD developments is “Evolution of Cellulose Triacetate (TAC) Films for LCDs: Novel Technologies for High Hardness, Durability, and Dimensional Stability” by Ryo Suzuki of Fujifilm Corp., which describes the development of different films that could solve stability problems caused by reductions in the thickness of polarizers and reduce warping in IPS-LCD TV panels.
An even more disruptive technology, notes Yan, are micro-sized LEDs, which he says could be the display industry’s “next big thing.” These LEDs integrate light source and optics, enabling high-pixel density and may be well-suited to 3-D displays, he says. Ostendo, last year’s Innovation Zone winner at Display Week, has a very interesting paper on this technology: “Quantum Photonic Imager (QPI): A Novel Display Technology that Enables more than 3D Applications,” by Hussein S. El-Ghoroury, which describes the QPI, a 3D-IC semiconductor device comprising a high-density array of digitally address-able micro-LED pixels.
OLEDs
The biggest trend in OLEDs, according to subcommittee chair Sven Zimmermann, are the TADF emitters mentioned in the disruptive materials section above. He believes these may soon be competitive with normal phosphorescent emitters (which contain heavy metals and have lifespan issues). TADF OLEDs also have a more uniform spectral distribution, which could make them strong candidates for lighting applications in particular.
Zimmermann notes that there are also several symposium papers on OLED TV. The current state of the art can be found in the paper “High-Performance Large-Sized OLED TV with UHD Resolution” from Yu-Hung Chen of AU Optronics Corp., in which the author and his team describe the architecture and fabrication of a high-performance 65-in. ultra-HD OLED TV with excellent visual quality that utilizes stable arrays and cutting-edge OLED processes.
Flexible, Foldable, Wearable
Flexible technology continues to be a hallmark of Display Week, and the most outstanding trend here is that flexible displays are entering a more mature phase, according to subcommittee chair Kevin Gahagan of Corning, who cites commercial examples that contain flexible displays, such as LG’s G Flex phone. Flexible papers this year reflect that relative maturity, he says, in that issues like scaling are more of a focus, as well as encapsulation and the integration of features such as touch and transparency. “The [whole] system has to be flexible,” he says.
Looking farther ahead, Gahagan thinks that foldable is the next frontier for flexible devices. “We’re seeing demos of foldable displays that are high resolution, with many bend cycles.” One example is “Foldable AMOLED Displays with a Touch Panel” from Jia-Chong Ho of ITRI. “There is a growing consensus that foldable is the ultimate form factor,” says Gahagan. “It’s easy to interact with.” Although the flexible display that can be rolled up and popped into a purse or briefcase has been the form factor most people imagine for the ultimate flexible display, the scroll can be problematic because when you write on it, it’s unsupported in the middle, explains Gahagan. “This might be speculation,” he says, “but foldable is where I think we’re headed.”
The category of flexible often meshes with wearable, and a case in point is the paper “Stretchable 45 × 80 RGB-LED Display Using Meander Wiring Technology” by Hideki Ohmae of Panasonic Corp. This paper describes a foldable and stretchable (up to 10%) fabric-like display that incorporates LEDs. Another wearable paper to look for is “High-Image-Quality Wearable Displays with Fast-Response Liquid Crystal” by Zhenyue Luo at the University of Central Florida. Luo reports on two ultra-low-viscosity liquid crystals with a field-sequential-color LCOS. The LC’s fast response time offers vivid color, a high ambient contrast ratio, low power consumption, and mitigated color breakup even in extremely low temperatures.
Touch, Liquid Crystals, and Projection
Touch technology has been an integral part of the display industry and Display Week for several years. Subcommittee chair Jeff Han notes that even though there may not seem to be as much touch news as there has been in the past: “Touch is still hot. People just don’t want to talk about it because companies integrating touch would have to describe their own stacks, etc.” In terms of trends: “In-cell is what it’s all about,” says Han. “I feel like the tide is turning in this regard [in the direction of vertical integration].” There are still plenty of touch papers at the symposium, with four separate sessions. The invited paper “Panel-Structure Evolution of In-Cell Capacitive Touch Sensor” by Qijun Yao of Shanghai Tianma Microelectronics Co. will look at various integration schemes for in-cell capacitive touch panels and review ongoing efforts being made to eliminate the interference between display and touch-sensor structure. That paper will also present an in-cell LCD module with an integrated self-capacitance touch sensor.
In terms of liquid crystals, besides the disruptive materials papers mentioned earlier, fringe-field switching (FFS) and in-plane switching (IPS) are current trends in the industry, according to subcommittee chair Philip Chen, as are suggested breakthroughs for blue phase involving a new structure. Look for the papers “A High-Transmittance IPS LC Mode Using a New Self-Aligned Structure” by Sun-Hwa Lee, of LG Display Co., “A Fast-Response A-film-Enhanced FFS LCD from AU Optronics Corp., and “A Blue-Phase LCD with Wall Electrode and High-Driving-Voltage Circuit” by Cheng-Yeh Tsai, also of AUO.
The biggest trend in projection this year is that solid-state light sources are replacing lamps, according to projection co-chair Dave Eccles. LEDs were much vaunted for projectors a few years ago, but are not really bright enough for most applications beyond pico projectors, explains Eccles. Laser phosphors, which have been described in papers at Display Week for some years, are now being used in commercial products. They can be employed for everything from pico projectors to digital-cinema projectors, says Eccles, though in digital-cinema applications, laser phosphor projectors are referred to as “non-coherent light” for public-relations purposes. A particularly educational and interesting paper to catch is “The Progress in International Safety Standards for Laser-Illuminated Projection Systems” by Greg Niven of LIPA. “This is a good one for people to hear because it will explain current standards for both the U.S. and the rest of world,” says Eccles.
Light-Field Displays
Yet another key technology not to be missed at Display Week is light-field displays. This is an area that is growing, says displays systems chair Kalil Käläntär. “Everyone is being challenged to ‘solve’ light-field displays, including 3D displays,” he says. “Light field would be a great candidate for next-generation displays.” To find out more, catch the invited paper “Design Principles for Light-Field Image Capture and Display” by Kathrin Berkner of Ricoh Innovations Corp., in which the author and her team discuss design principles for task-specific light-field camera systems and outline how such principles can be applied to the design of personal light-field displays.
Special Mini-Symposia
New to Display Week in 2015 is the addition of three Mini-Symposia in the form of Special Technology Tracks on Lighting, Vehicle Displays and Trends, and Imaging Technologies and Applications.
SID/IES Lighting: There has always been a great deal of overlap in the technology behind lighting and displays. In recognition of the newly signed Friendship Agreement between SID and the Illuminating Engineering Society of North America (IESNA), the SID/IES Lighting Track aims to deliver in-depth coverage in a diverse range of topics of common interest to both lighting and display professionals. This Mini-Symposium is scheduled for Thursday, June 4, and will consist of the following four sessions:
• Advanced Light Sources, Components, and Systems I
• Advanced Light Sources, Components, and Systems II
• Effects of Lighting on Health and Perception
• Advanced Lighting Applications
There will be additional OLED lighting sessions outside of this 1-day event for more in-depth discussions on OLED device physics and materials. Access to this 1-day Mini-Symposium is included for those attending the Display Week Symposium. It is also available as a stand- alone event to our guests from IESNA. For further registration information, go to www.displayweek.org/2015/Attendee/Registration.aspx
Vehicle Displays and Trends: This program will bring together scientists, engineers, market analysts, and industry leaders from the display, touch, photonics, and vehicle systems communities for a unique one of a kind event exploring the recent developments and trends of vehicle displays. This Mini-Symposium is also scheduled for Thursday, June 4, and will consist of a morning and afternoon plenary talk and the following four sessions:
• Next-Generation Automotive Display Technologies I: HUDs
• Automotive Display Applications and Systems
• Touch, Interactivity, and Human-Machine Interface
• Next-Generation Automotive Display Technologies II: Flexible, Curved, Coatings
Access to this 1-day Mini-Symposium is included for those attending the Display Week Symposium. It is also available as a stand-alone event. For further registration information, go to www.displayweek.org/2015/ Attendee/Registration.aspx.
Imaging Technologies and Applications: The Mini-Symposium on Imaging Technologies and Applications will feature invited papers covering the areas of imaging technologies, products, applications, advanced developments, and emerging trends. This focused track will bring together scientists, engineers, business professionals, market analysts, academic, and industry leaders pioneering the end-to-end chain of imaging to display technologies and applications. Scheduled for Tuesday, June 2, it will consist of three sessions of invited papers that include:
• “On the Duality of Compressive Imaging and Display” Gordon Wetzstein, Stanford University
• “Image Systems Simulation” Joyce Farrell, Stanford University
• “The Importance of Focus Cues in 3D Displays” Martin Banks, University of California at Berkeley, Berkeley, CA, USA
• “Light-Field Imaging” Kurt Akeley, Lytro
• “Interactive Systems and Applications Based on Depth-Imaging and 3D-Sensing Technology” Achin Bhowmik, Intel Corp.
Access to this 1-day Mini-Symposium is included for those attending the Display Week Symposium. For further registration information, go to www.displayweek.org/2015/Attendee/Registration.aspx.
Keep Up the Pace
As always, there is more to see and hear at the Display Week Symposium than one person can see and hear, and we’ve only been able to mention a few examples here. Other recommended presentations include the special lighting sessions, vehicle display sessions, display measurement papers that look at metrics for curved displays and transparent displays, near-to-eye display presentations – the list is nearly endless. Whatever you do, don’t miss the technical symposium at Display Week. It’s the best way to keep up with the pace of the display industry. •