A flexible display is an electronic visual display which is flexible in nature; as opposed to the more prevalent traditional flat screen displays used in most electronics devices. In recent years there has been a growing interest from numerous consumer electronics manufacturers to apply this display technology in e-readers, mobile phones and other consumer electronics.
Flexible electronic paper based displays
Flexible electronic paper (e-paper) based displays were the first flexible displays conceptualized and prototyped. Though this form of flexible displays has a long history and were attempted by many companies, it is only recently that this technology began to see commercial implementations slated for mass production to be used in consumer electronic devices.
The concept of developing a flexible display was first put forth by Xerox PARC (Palo Alto Research Company). In 1974, Nicholas K. Sheridon, a PARC employee, made a major breakthrough in flexible display technology and produced the first flexible e-paper display. Dubbed Gyricon, this new display technology was designed to mimic the properties of paper, but married with the capacity to display dynamic digital images. Sheridon envisioned the advent of paperless offices and sought commercial applications for Gyricon. In 2003 Gyricon LLC was formed as a direct subsidiary of Xerox to commercialize the electronic paper technology developed at Xerox PARC. Gyricon LLC's operations were short lived and in December 2005 Xerox closed the subsidiary company in a move to focus on licensing the technology instead.
HP and ASU
In 2005, Arizona State University opened a 250,000 square foot facility dedicated to flexible display research named the ASU Flexible Display Center (FDC). ASU received $43.7 million from the U.S. Army Research Laboratory (ARL) towards the development of this research facility in February 2004. A planned prototype device was slated for public demonstration later that year. However, the project met a series of delays. In December 2008, ASU in partnership with Hewlett Packard demonstrated a prototype flexible e-paper from the Flexible Display Center at the university. HP continued on with the research, and in 2010, showcased another demonstration. However, due to limitations in technology, HP stated "[our company] doesn't actually see these panels being used in truly flexible or rollable displays, but instead sees them being used to simply make displays thinner and lighter."
Between 2004–2008, ASU developed its first small-scale flexible displays. Between 2008–2012, ARL committed to further sponsorship of ASU’s Flexible Display Center, which included an additional $50 million in research funding. Although the U.S. Army funds ASU’s development of the flexible display, the center’s focus is on commercial applications.
This company develops and manufactures monochrome plastic flexible displays in various sizes based on its proprietary organic thin film transistor (OTFT) technology. They have also demonstrated their ability to produce colour displays with this technology, however they are currently not capable of manufacturing them on a large scale. The displays are manufactured in the company's purpose-built factory in Dresden, Germany, which was the first factory of its kind to be built – dedicated to the high volume manufacture of organic electronics. These flexible displays are cited as being "unbreakable", because they are made completely of plastic and do not contain glass. They are also lighter and thinner than glass-based displays and low-power. Applications of this flexible display technology include signage, wristwatches and wearable devices as well as automotive and mobile devices.
Organic User Interfaces and the Human Media Lab
In 2004, a team led by Prof. Roel Vertegaal at Queen's University's Human Media Lab in Canada developed PaperWindows, the first prototype bendable paper computer and first Organic User Interface. Since full-colour, US Letter-sized displays were not available at the time, PaperWindows deployed a form of active projection mapping of computer windows on real paper documents that worked together as one computer through 3D tracking. At a lecture to the Gyricon and Human-Computer Interaction teams at Xerox PARC on 4 May 2007, Prof. Vertegaal publicly introduced the term Organic User Interface (OUI) as a means of describing the implications of non-flat display technologies on user interfaces of the future: paper computers, flexible form factors for computing devices, but also encompassing rigid display objects of any shape, with wrap-around, skin-like displays. The lecture was published a year later as part of a special issue on Organic User Interfaces in the Communications of the ACM. In May 2010, the Human Media Lab partnered with ASU's Flexible Display Center to produce PaperPhone, the first flexible smartphone with a flexible electrophoretic display. PaperPhone used bend gestures for navigating contents. Since then, the Human Media Lab has partnered with Plastic Logic and Intel to introduce the first flexible tablet PC and multi-display e-paper computer, PaperTab, at CES 2013, debuting the world's first actuated flexible smartphone prototype, MorePhone in April 2013.
Since 2010 Sony Electronics, AU Optronics and LG Electronics have all expressed interest in developing flexible e-paper displays. However, only LG have formally announced plans for mass production of flexible e-paper displays.
Flexible OLED-based displays
Research and development into flexible OLED displays largely began in the late 2000s with the main intentions of implementing this technology in mobile devices. However, this technology has recently made an appearance, to a moderate extent, in consumer television displays as well.
Nokia Morph and Kinetic concepts
Nokia first conceptualized the application of flexible OLED displays in mobile phone with the Nokia Morph concept mobile phone. Released to the press in February 2008, the Morph concept was project Nokia had co-developed with the University of Cambridge. With the Morph, Nokia intended to demonstrate their vision of future mobile devices to incorporate flexible and polymorphic designs; allowing the device to seamlessly change and match a variety of needs by the user within various environments. Though the focus of the Morph was to demonstrate the potential of nanotechnology, it pioneered the concept of utilizing a flexible video display in a consumer electronics device. Nokia renewed their interest in flexible mobile devices again in 2011 with the Nokia Kinetic concept. Nokia unveiled the Kinetic flexible phone prototype at Nokia World 2011 in London, alongside Nokia’s new range of Windows Phone 7 devices. The Kinetic proved to be a large departure from the Morph physically, but it still incorporated Nokia's vision of polymorphism in mobile devices.
Sony Electronics expressed interest for research and development towards a flexible display video display since 2005. In partnership with RIKEN (the Institute of Physical and Chemical Research), Sony promised to commercialize this technology in TVs and cellphones sometime around 2010. In May 2010 Sony showcased a rollable TFT-driven OLED display.
In late 2010, Samsung Electronics announced the development of a prototype 4.5 inch flexible AMOLED display. The prototype device was then showcased at Consumer Electronics Show 2011. During the 2011 Q3 quarterly earnings call, Samung’s vice president of investor relations, Robert Yi, confirmed the company’s intentions of applying the technology and releasing products utilizing it by early 2012. In January 2012 Samsung acquired Liquavista, a company with expertise in manufacturing flexible displays, and announced plans to begin mass production by Q2 2012. During Samsung's CES 2013 keynote presentation, two prototype mobile devices codenamed "Youm" that incorporated the flexible AMOLED display technology were shown to the public.
Samsung subsequently released the Galaxy Round, a smartphone with an inward curving screen and body, in October 2013. One of the Youm concepts, which featured a curved screen edge used as a secondary area for notifications and shortcuts, was developed into the Galaxy Note Edge released in 2014. In 2015, Samsung applied the technology to its flagship Galaxy S series with the release of the Galaxy S6 Edge, a variant of the S6 model with a screen sloped over both sides of the device. During a developer conference in 2018, Samsung showed a foldable smartphone prototype, which was subsequently revealed in February 2019 as the Galaxy Fold.
The Flexible Display Center (FDC) at Arizona State University announced a continued effort in forwarding flexible displays in 2012. On 30 May, in partnership with Army Research Lab scientists, ASU announced that it has successfully manufactured the world's largest flexible OLED display using thin-film transistor (TFTs) technology. ASU intends the display to be used in "thin, lightweight, bendable and highly rugged devices."
In January 2019, Chinese manufacturer Xiaomi showed a foldable smartphone prototype. CEO Lin Bin of Xiaomi demoed the device in a video on the Weibo social network. The device features a large foldable display that curves 180 degrees inwards on two sides. The tablet turns into a smartphone, with a screen diagonal of 4,5 inch, adjusting the user interface on the fly.
Flexible displays using electronic paper technology commonly use Electrophoretic or Electrowetting technologies. However, each type of flexible electronic paper vary in specification due to different implementation techniques by different companies.
HP and ASU e-paper
The flexible electronic paper display technology co-developed by Arizona State University and HP employs a manufacturing process developed by HP Labs called Self-Aligned Imprint Lithography (SAIL). The screens are made by layering stacks of semi-conductor materials and metals between pliable plastic sheets. The stacks need to be perfectly aligned and stay that way. Alignment proves difficult during manufacturing when heat during manufacturing can deform the materials and when the resulting screen also needs to remain flexible. The SAIL process gets around this by ‘printing’ the semiconductor pattern on a fully composed substrate, so that the layers always remain in perfect alignment. The limitation of the material the screen is based on allows only a finite amount of full rolls, hence limiting its commercial application as a flexible display. Specifications provided regarding the prototype display are as follows:
The flexible electronic paper display announced by AUO is unique as it is the only solar powered variant. A separate rechargeable battery is also attached when solar charging is unavailable. Specifications
- 6-inch diagonal display size
- radius of curvature can reach 100mm
- 9:1 high contrast ratio
- reflectance of 33%
- 16 gray levels
- solar powered
- 6-inch diagonal display size
- 1024x768 (XGA) resolution
- 4:3 aspect ratio
- TFT based electronic display
- "allows bending at a range of 40 degrees from the center of the screen"
- 0.7mm thickness from the side
- 14g weight
- can drop from 1.5m above ground with no resultant damage
- "unbreakable" (from tests with a small urethane hammer)
List of displays by their reported curvature
|Model||Diagonal (in)||Radius of curvature*||Curved along its wider / shorter side?|
|Samsung Round||5.7||400 millimetres (16 in)||shorter|
|LG G Flex||6||700 millimetres (28 in)||wider|
|Samsung KN55S9C||54.6||4,500 millimetres (180 in)||wider|
|LG 55EA9800||54.6||5,000 millimetres (200 in)||wider|
*Lower is more sharply curved
Many of the e-paper based flexible displays are based on OLED technology and its variants. Though this technology is relatively new in comparison with e-paper based flexible displays, implementation of OLED flexible displays saw considerable growth in the last few years.
- 6-inch diagonal display size
- 480x360 4k resolution
- 4:3 aspect ratio
- OLED display technology with a TFT back plane
In May 2011, Human Media Lab at Queen's University in Canada introduced PaperPhone, the first flexible smartphone, in partnership with the Arizona State University Flexible Display Center. PaperPhone used 5 bend sensors to implement navigation of the user interface through bend gestures of corners and sides of the display. In January 2013, the Human Media Lab introduced the first flexible tablet PC, PaperTab, in collaboration with Plastic Logic and Intel Labs, at CES. PaperTab is a multi-display environment in which each display represents a window, app or computer document. Displays are tracked in 3D to allow multidisplay operations, such as collate to enlarge the display space, or pointing with one display onto another to pull open a document file. In April 2013 in Paris, the Human Media Lab, in collaboration with Plastic Logic, unveiled the world's first actuated flexible smartphone prototype, MorePhone. MorePhone actuates its body to notify users upon receiving a phone call or message.
Nokia introduced the Kinetic concept phone at Nokia World 2011 in London. The flexible OLED display allows users to interact with the phone by twisting, bending, squeezing and folding in different manners across both the vertical and horizontal planes. The technology journalist website Engadget described interactions such as "[when] bend the screen towards yourself, [the device] acts as a selection function, or zooms in on any pictures you're viewing." Nokia envisioned this type of device to be available to consumers in "as little as three years", and claimed to already possess "the technology to produce it."
At CES 2013, Samsung showcased the two handsets which incorporates AMOLED flexible display technology during its keynote presentation, the Youm and an unnamed Windows Phone 8 prototype device. The Youm possessed a static implementation of flexible AMOLED display technology, as its screen has a set curvature along one of its edges. The benefit of the curvature allows users "to read text messages, stock tickers, and other notifications from the side of the device even if [the user] have a case covering the screen." The unnamed Windows Phone 8 prototype device was composed of a solid base from that extends a flexible AMOLED display. The AMOLED display itself bends and was described as "virtually unbreakable even when dropped" according to Samsung representatives. Brian Berkeley, the senior vice president of Samsung Display, believes that this flexible form factor "will really begin to change how people interact with their devices, opening up new lifestyle possibilities ... [and] allow our partners to create a whole new ecosystem of devices." The Youm's form factor was ultimately utilized on the Galaxy Note Edge, and future Samsung Galaxy S series devices.
Curved OLED TVs
LG Electronics and Samsung Electronics both introduced curved OLED televisions with a curved display at CES 2013 hours apart from each other. Both companies recognized their respective curved OLED prototype television as a first-of-its-kind due to its flexed OLED display. The technology journalist website The Verge noted the subtle curve on 55" Samsung OLED TV allowed it to have a "more panoramic, more immersive viewing experience, and actually improves viewing angles from the side." The experience was also shared viewing the curved 55" LG OLED TV. The LG set is also 3D capable, in addition to the curvature.
|Model||Diagonal (in)||Radius of curvature (mm)*|
*Lower is more sharply curved
- Genuth, Iddo (15 October 2007). "The Future of Electronic Paper". The Future of Things. Retrieved 12 February 2013.
- "Gyricon LLC and the World of Electronic Paper". Xerox PARC. 9 December 2003. Retrieved 12 February 2013.
- Hamilton, Brian (15 December 2005). "Xerox erases electronic paper subsidiary, Gyricon LLC, in Scio Twp". Ann Arbor Business Review. Archived from the original on 1 May 2006. Retrieved 12 February 2013.
- "ASU, Army Open New Flexible Display Center". Arizona State University. 2005. Retrieved 12 February 2013.
- Perton, Marc (9 February 2005). "Arizona State opens flexible-display center". Engadget. Retrieved 12 February 2013.
- Hamilton, Brian (8 December 2008). "HP and ASU demo bendable, unbreakable electronic displays". Engadget. Retrieved 12 February 2013.
- Melanson, Donald (20 March 2010). "HP flexible display unfurled on video". Engadget. Retrieved 12 February 2013.
- "Army continues Flexible Display Center support". ASU Now: Access, Excellence, Impact. 29 January 2009. Retrieved 30 July 2018.
- Derra, Skip. "ASU, Army Open New Flexible Display Center". ASU.
- "Lectum Displays – FAQ: Are Lectum displays available in color?". Plastic Logic. 7 April 2016.
- Thryft, Ann R. (7 June 2012). "All-Plastic Electronics Power Flexible Color Display". Design News.
- Kozlowski, Michael (4 September 2012). "Plastic Logic Shows Off New 10.7 Color Display Screen". Good e-Reader.
- "Plastic Logic Opens World's First Commercial Plastic Electronics Manufacturing Factory". Reuters. 17 September 2008.
- McGlaun, Shane (5 March 2013). "Plastic Logic unveils 42-inch flexible plastic signage prototype". Slash Gear.
- "SERELEC and Plastic Logic introduce ZED – a low-power outdoor digital signage solution". Plastic Logic. 28 January 2013.
- Lowe, Mike (26 March 2013). "Plastic Logic shows off colour e-paper display smart watch concept: the future of wearable tech?". Pocket-lint Gadget.
- "Bend me, shape me: Flexible phones 'out by 2013'". BBC News. 30 November 2012.
- Holman, D., Vertegaal, R. and Troje, N. (2005). PaperWindows: Interaction Techniques for Digital Paper. In Proceedings of ACM CHI 2005 Conference on Human Factors in Computing Systems. ACM Press, 591–599.
- Holman, David; Vertegaal, Roel (2008). "Organic user interfaces". Communications of the ACM. 51 (6): 48. doi:10.1145/1349026.1349037.
- Lahey, Byron; Girouard, Audrey; Burleson, Winslow and Vertegaal, Roel (May 2011). PaperPhone: Understanding the Use of Bend Gestures in Mobile Devices with Flexible Electronic Paper Displays, Proceedings of the SIGCHI Conference on Human Factors in Computing Systems, Pages 1303–1312.
- Zhao, Hommer (2013) Paper Tab-Revolutionary High Tech Quick Introducing. wellpcb.com
- Gomes, A., Nesbitt, A., and Vertegaal, R. (2013) MorePhone: A Study Of Actuated Shape Deformations for Flexible Thin-Film Smartphone Notifications. In Proceedings of ACM CHI’13 Conference on Human Factors in Computing. ACM Press, 2013, pp. 583–592.
- AUO News Center (20 October 2009). "AUO Unveils Flexible E-Paper Technology". AU Optronics. Retrieved 12 February 2013.
- Savov, Vlad (15 September 2010). "Sony demoes flexible electronic paper display, tickles our fancy". Engadget. Retrieved 12 February 2013.
- Hollister, Sean (28 March 2012). "LG begins mass production of flexible e-paper display". The Verge. Retrieved 12 February 2013.
- Nokia Research Center (February 2008). "The Morph Concept". Nokia. Archived from the original on 8 July 2015. Retrieved 12 February 2013.
- Nokia Press Center (25 February 2008). "Nokia and University of Cambridge launch the Morph – a nanotechnology concept device". Nokia. Retrieved 12 February 2013.
- Davies, Trevor (28 October 2011). "Nokia Kinetic bendy phone is the next big thing". Conversations by Nokia. Retrieved 12 February 2013.
- Nokia Press Center (26 October 2011). "Nokia showcases bold portfolio of new phones, services and accessories at Nokia World". Nokia. Archived from the original on 27 January 2013. Retrieved 12 February 2013.
- Rojas, Peter (8 July 2005). "Sony's new ultrathin rollable display prototype". Engadget. Retrieved 12 February 2013.
- Ricker, Thomas (26 May 2010). "Sony's rollable OLED display can wrap around a pencil, our hearts". Engadget. Retrieved 12 February 2013.
- Murph, Darren (4 November 2010). "Samsung showcases 4.5-inch flexible AMOLED, may actually mass produce this one". Engadget. Retrieved 12 February 2013.
- Ziegler, Chris (9 January 2011). "Samsung shows flexible and transparent displays at CES 2011". Engadget. Retrieved 12 February 2013.
- O'Dell, Jolie (28 October 2011). "Samsung's new phones will have flexible screens". Engadget. Retrieved 12 February 2013.
- Hollister, Sean (19 January 2011). "Samsung buys Liquavista, dives headfirst into electrowetting displays". Engadget. Retrieved 12 February 2013.
- Keene, Jamie (28 October 2011). "Samsung to launch phones with flexible screens as early as next year". The Verge. Retrieved 12 February 2013.
- Lee, Reuben (10 January 2013). "Samsung shows off flexible display phones at CES keynote". CNET. Archived from the original on 17 February 2013. Retrieved 12 February 2013.
- "Samsung's Galaxy Round is the first phone with a curved display". The Verge. Vox Media. 9 October 2013. Retrieved 21 March 2017.
- "The Galaxy Note Edge: Samsung's first smartphone with a bent display". Engadget. Retrieved 7 January 2015.
- Pierce, David (26 March 2015). "The Galaxy S6 Edge Is Totally Beautiful—And Pointless". Wired. Retrieved 4 April 2015.
- "Samsung's foldable phone is real and opens into a tablet". CNET. Retrieved 13 November 2018.
- White, Jeremy (20 February 2019). "The Samsung Galaxy Fold breathes new life into phones (at a price)". Wired UK. ISSN 1357-0978. Retrieved 20 February 2019.
- "The Flexible Display Center Produces Largest Flexible Color OLED Display Manufactured With Mixed Oxide Thin Film Transistors". Market Wire. 30 May 2012. Retrieved 12 February 2013.
- Streams, Kimber (6 June 2012). "ASU's 7.4-inch full-color flexible OLED display is the world's largest". The Verge. Retrieved 12 February 2013.
- "Xiaomi teases a double folding phone". Foldable News. 23 January 2019. Retrieved 23 January 2019.
- HP Press Center (Spring 2009). "HP and Arizona State University Demo Flexible, Unbreakable Displays". HP. Retrieved 12 February 2013.
- Parish, Joseph (28 October 2011). "AUO makes flexible solar powered epaper". The Verge. Retrieved 12 February 2013.
- Toor, Amar (29 March 2012). "LG unveils flexible plastic e-paper display, aims for European launch next month". Engadget. Retrieved 12 February 2013.
- ASU Press Center (February 2012). "ASU Flexible Display Center Milestones". ASU. Retrieved 12 February 2013.
- "Samsung Highlights Innovations in Mobile Experiences Driven by Components, in CES Keynote". Samsung Electronics. 9 January 2013. Retrieved 12 February 2013.
- D'Orazio, Dante (9 January 2013). "Samsung shows off flexible AMOLED phone prototype (hands-on)". The Verge. Retrieved 12 February 2013.
- Savov, Vlad (1 November 2011). "Nokia Kinetic device demo". The Verge. Retrieved 12 February 2013.
- Smith, Mat (26 October 2011). "Nokia's kinetic future: flexible screens and a twisted interface". Engadget. Retrieved 12 February 2013.
- Lowensohn, Josh (9 January 2013). "Eyes-on: Samsung's Youm flexible-display tech at CES 2013". CNET. Retrieved 12 February 2013.
- Warman, Matt (10 January 2013). "CES 2013: Samsung flexible phone prototype unveiled". London: The Daily Telegraph. Retrieved 12 February 2013.
- Amadeo, Ron (23 February 2015). "T-Mobile shows off the Samsung Galaxy S6 design, curved screen and all". Ars Technica. Retrieved 23 February 2019.
- Reflex; World's First Bendable Smartphone Dubbed As ReFlex; Prototype Revealed By Queen's University's Human Media Lab
- Pierce, David (8 January 2013). "Samsung introduces 'world's first' curved OLED TV". The Verge. Retrieved 12 February 2013.
- Pierce, David (8 January 2013). "Battle of the curved OLED TVs: LG matches Samsung with its own 'world's first'". The Verge. Retrieved 12 February 2013.
- "SAMSUNG Introduces World's First Curved OLED TV at CES 2013". Samsung Electronics. 8 January 2013. Retrieved 12 February 2013.
- "LG SHOWS ITS FIRST OLED TV WITH CURVED SCREEN". LG Electronics. 9 January 2013. Retrieved 12 February 2013.
- 겉과 속이 다른 삼성 curved OLED TV. olednet.co.kr (4 August 2013)