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Flexible Displays and E-paper
Maxim Dolgobrod
Advanced Display and Image Technologies
Contents
• What are flexible displays
• Current status
• Development roadmap
• Challenges
• Market
• Main technologies
• Application
• Future
• Conclusion
What is a flexible display?
Flexible displays are essentially very thin display screens that can be
printed onto flexible or stretchable material and then attached to other
surfaces or produced in a variety of shapes.
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Flexible display
• Ultimate flexible display is a combination of TFT-LCD and OLED
techniques— with advances developed in various fields such as processing,
component, and materials.
• Display might not be flexible in its application
• Core materials:
– semiconductor material
– insulation material
– electrode material
– substrate
Substrate
• substrate is critical to flexible displays
development
• different types of materials are under
investigation, including glass, plastic, polymer
films, and metallic foils
• must be readily bendable and rollable
• must accommodate different types of display
technologies at high levels of brightness,
contrast ratios, and resolution
• must offer low power dissipation
• should be able to provide full-color capability to
enhance their market acceptability
Current status
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There is a considerable research
Most of technologies are still in development and available in form of
prototypes
The display panel itself is only a small part of the battle. All the ancillary
electronics, the power, transistors and circuitry are all things today that are
not yet fully flexible at large scales.
Industry interest and competition is fierce
The Flexible Display Center, at Arizona State University: flexible displays
ready for test trials in approximately 3 years.
Currently E Ink one of most popular technologies available for commercial
use
Flexible displays roadmap
Source: Displaybank, 'Flexible Display Technology and Market (2007~2017)' report
Challenges
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From traditional rigid substrates to flexible substrate
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Satisfy the requirements of both substrate and deposited electronics
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Handle the high processing temperatures encountered when making
rigid displays
Laminate adhesives that can perform reliably at high temperatures
without being affected by stresses
Achieving large quantity supply with comparative low cost
Flexible displays market - demand forecasts
Source: Displaybank, 'Flexible Display Technology and Market (2007~2017)' report
History
1970
Electronic paper first developed at Xerox's Palo Alto Research Center
1990
Printing of OLED on flexible substrate discovered
2000
World's first flexible display using electronic ink from E Ink Corporation
2002
Philips finds way to 'paint' LCD screens
2007
First production-ready flexible display manufacturing method developed
by FlexiDis, a European-Commission funded technology project
2008
Hewlett-Packard and Arizona State University introduce a prototype of
a paper-like, flexible computer display made almost entirely of plastic
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Main flexible display technologies
Flexible LCDs
FOLED, Flexible AMOLED
E-paper: Electrophoretic, Cholesteric LCDs,
Electrowetting Displays (EWD), Electrochromic Displays
Interferometric Modulator Technology
Flexible LCDs
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Many display experts believe LCDs are most likely to succeed
in large-scale, cost-effective flexible displays
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Samsung prototyped 5-in. diagonal LCD panel that uses amorphous
silicon TFTs.
Fujitsu has shown monochrome and color cholesteric LCD, flexible, 3.8in. diagonal panel.
Pixel-isolated LCDs for enhancing a flexible LCD's mechanical stability
Flexible LCDs
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FOLED
• Organic light emitting device (OLED) built on a flexible base material, such
as clear plastic film or reflective metal foil, instead of the usual glass base.
• Developed by Universal Display Coporation
• Started in 1990s after discovery by research partner at Princeton University
that small-molecule OLEDs could be built on flexible substrates
FOLED
Source: Universal Display Corporation
FOLED developed by Universal Display Corporation.
Passive matrix display: 0.175 mm thick sheet of plastic, resolution of 80 dpi; 64 levels
of grey scale; can show full motion video.
Credit: Image courtesy of Universal Display Corporation.
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FOLED
Pros
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Brighter than LCDs
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Wider viewing angles and faster
response times
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Don't need a backlighting source
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Thinner and lighter weight
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Cons
More durable, safer and impact
resistant
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Flexible
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Cost-effective
Require a strong barrier against
moisture
Limited lifetime particularly for the blue
color
t
Vaio with flexible OLED screen
(Credit: Scott Ard/CNET)
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The Sony Reader and Walkman redone with flexible OLED technology.
(Credit: Scott Ard/CNET)
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Flexible AMOLED
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enables a lighter and thinner display
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high refresh rate
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rugged and not prone to breakage
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consume significantly less power
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large area displays can be made cheaply
because of the low temperature process used
and their possible roll-to-roll manufacturing.
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at the proof-of-concept stage for conformable
and rollable displays
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Samsung is the leading developer of AMOLED
displays
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2009 world’s first flexible AMOLED display with
a 6.5” screen announced
LCD vs Flexible AMOLED
Winner!
Electronic paper, e-paper
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A display technology designed to mimic the appearance of ordinary ink on paper
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Also known as Electrophoretic Paper Display or EPD
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Capable of holding text and images indefinitely without drawing electricity, while
allowing the image to be changed later
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More comfortable to read than conventional displays due to stable image
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Considered an eco-friendly technology due to low power consumption
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More than a dozen companies have announced work on active e-paper programs
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Colour prototypes exist, but their commercialistaion has yet to be started
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EPD only recently took off as "the" modern textual and still image display technology
E-paper: key features
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Flexible and durable
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Impact resistant
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Long lifetime: It can be updated up to 1 million times
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Image retain without power
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Reflects light like ordinary paper
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Extremely thin
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High contrast
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Wide view angle: almost 180 degree
E-paper
• First developed in 1970s by Xerox inspired by the idea of a paperless office
• Fujitsu, E Ink and others introduced the EPD in film (active matrix display),
flexible form, Seiko launched the first e-paper wristwatch in 2005
• In November 2007 the EPD finally hits the market with Amazon launching
Kindle, Sony its e-reader, Bookeen launched the Cybook and iRex its iLiad.
• In March 2009 Fujitsu begins consumer sales of world’s first color e-paper
mobile terminal FLEPia
Electronic paper
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Comprises two different parts:
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electronic ink, "frontplane”
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electronics required to generate the pattern of text and images on the e-ink page, the
"backplane".
E-paper: production aspects
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The production structure of electronic paper is fairly complex.
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In many cases this manufacturing is contracted out.
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Backplane is manufactured by another group of firms.
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Additional group of firms—consumer product firms—who design and market the
product into which the e-paper display fits
For example, the e-readers marketed under the Sony brand have incorporated
e-paper technology from E Ink and backplane technology from Polymer Vision.
E-paper: frontplanes
•Electrophoretic Technology
•Electrochromic Technology
•E Ink
•Acreo
•SiPix
•Aveso
•Bridgestone
•Ntera
•Cholesteric LCD Technology
•Fujitsu
•Hitachi
•Kent Display
•Kodak
•Nemoptic
•ZBD Display
•Electrowetting Technology
•Liquivista
•Electrofluidic Technology
•Gamma Dynamics
•Siemens
•Interferometric Modulator Technology
•Qualcomm
•Photonic Crystal Technology
•Opalux
•REED Technology
•Zikon
•Bistable LCDs
E-paper: backplanes
• HP
• NEC
• Plastic Logic
• Polymer Vision
• Prime View International
• Ricoh
• Samsung
• Seiko Epson
Gyricon
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first electronic paper
greek for ”rotating image”
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based on electrocapillarity : movement of coloured liquids against a white background
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consists of polyethylene spheres between 75 and 106 micrometres across embedded
in a transparent silicone sheet, with each sphere suspended in a bubble of oil so that
they can rotate freely. Each coloured sphere is white on one side and black on the
other.
Xerox closed its Gyricon operation in December 2005 for financial reasons, but is still
licensing technology to other companies
Further developed by other companies
at the FPD 2008 exhibition, Japanese company Soken has demonstrated a wall with
electronic wall-paper using this technology
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E Ink
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E Ink is a specific proprietary type of electronic paper
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Also know as electrophoretic frontplane technology
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Manufactured by E Ink Corporation, founded in 1997 based on research
started at the MIT Media Lab
Currently mostly available commercially in grayscale
Commonly used in mobile devices such as e-Readers and to a lesser extent
mobile phones and watches
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Material is processed into a film for integration into electronic displays
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Main use for an text-based rendering
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E Ink
Microcapsules, ~ 100 microns in diameter
E Ink with color filters
E Ink
Cons
Pros
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paper-like high contrast
appearance
twice the contrast of a LCD
panel
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ultra-low power consumption
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thin, light form
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unrestricted size
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slow response time, not suitable for
motion picture
not possible to implement
sophisticated interactive
applications due to response time
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ghosting
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costly
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iLiad e-reader
in sunlight
Citizen's flexible digital wall
clock
 21-inches x by 52-inches
 battery lasts 20 h more than
traditional digital clock
 costs $4000+
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Cholesteric liquid crystal displays (ChLCD)
• Developed by companies IBM, Philips, HP and Fujitsu,
which have demonstrated actual devices
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Cholesteric liquid crystal
– same crystals as in LCDs
– a type of liquid crystal with a helical structure
– by applying a current crystals change from a vertical
to a horizontal position.
• ChLCD technology could become the dominant e-paper
technology of the next decade.
Cholesteric liquid crystal displays (ChLCD)
Pros
• flexibility and even bendability
• thinness, at approximately 0.8 millimeters
• Lightness
• a bi-stable nature, requiring no power to maintain an image and very little
power to change it
• good brightness, contrast, and resolution;
• vivid color and a decent refresh rate capable of displaying animation and
possibly even video.
Electrowetting display (EWD)
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Developed and patented by Dutch company called Liquavista
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Merges the advantages of LCDs and e-ink displays
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Uses a process called electrowetting, which uses small electrical charges to
move colored oil within each pixel
Electrowetting is a proven process, used for focus mechanisms in cameras
and cellphones
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All the assets of LCD, but with 2x, 3x, 4x the performance
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Fundamentally brighter, more colourful displays
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Simplified LCD-like manufacturing process
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Initially targeted at e-reader markets followed by mobile phones
Electrowetting display (EWD)
EWD
Source: www.displaysearchblog.com
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EWD
Pros
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uses natural forces and simple
materials
frame rate 60 times per second,
enough to run videos
work well in sunlight and viewed
picture gets even crisper
3 to 4 more efficient than LCD
screens because of the higher level
of backlight passing through each
pixel.
large number of grey scales
Cons
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oil response speed
getting enough light to reflect
back off the screen in sunshine
mass-productions aspects
Electrochromic Displays
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Display consists of a layer of electrochromic material sandwiched between two electrode layers.
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Material changes from one colour to another when stimulated by an electric current. The top electrode layer is
made from transparent plastic
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The electrochromic mixture used by Siemens, which enables the screen to work so rapidly, include conductive
polymers such as polyaniline.
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The display is controlled by a printed circuit and can be powered by a very thin printable battery or a
photovoltaic cell.
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The goal is to be able to create the entire device“ the display and its power source – using the same printing
method, so that manufacturing costs would be as low as possible.
mirasol displays - fullcolor e-paper
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Developed by Qualcomm MEMS Technologies, Inc.
Uses a reflective technology, called interferometric modulation (IMOD). The
technology uses microelectromechanical systems (MEMS) technology to
imitate the way butterfly wings shimmer - a process called biomimetics, or
imitating things found in nature.
In December of 2008 the Institute of Industrial Science (IIS) of the University
of Tokyo developed a MEMS display by using roll-to-roll printing technology
Expected to be seen on cell phones, e-book readers and tablets by the end
of 2010
Mirasol low-power MEMS display for e-readers, in a proof-of-concept built by Qualcomm.
Image: Qualcomm MEMS Technologies, Inc.
mirasol displays
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mirasol displays
Pros
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color
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very low power consumption, no backlight
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easy to view in the sunlight
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no delay in screen refreshing due to faster refresh rate
Amazon Kindle
• 6" E Ink electronic paper display
• 600 x 800 pixel resolution at 167 ppi
• 16-level gray scale
• Price: $259
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Fujitsu Flepia
• 8” Color e-paper
• 768 dots x 1,014 dots (XGA)
• Color
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260,000 colors (3 Scans)
4,096 (2 Scans)
64 colors (1 Scan)
• Redraw speed:
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1.8 seconds (1 Scan)
5 seconds (2 Scans)
8 seconds (3 Scans)
• Price: ~ 849 €
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Application areas
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Newspapers
• Interior design
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E-books
• Smart cards
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Digital signage
• Automotive consoles
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Medical
• Mobile
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Toys and games
• Military equipment
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Clothing
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TVs
Future
The Morph concept from Nokia
Image: Nokia
Holy grail of e-paper
Will be embodied as a cylindrical tube, about 1 centimeter in
diameter and 15 to 20 centimeters long, that a person can
comfortably carry in his or her pocket. It will cost less than $100.
Conclusion
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E-paper display technology has now become an integral part of ebook reading
devices.
2010 year of e-paper based devices. CES 2010 had a lot of new e-paper devices
being announced.
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Color e-paper to come in few years, first products possibly in 2011 -2012
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The technology of printed electronics will deliver low-cost production
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Give away e-paper display products by 2015.
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Content availability
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Questions?
Questions?
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Thank you!