Flexible
Displays
Nandhaan Verma
E&EC, 12105044
PEC University of Technology
Chandigarh, India
nandhaan_hawkman@yahoo.com
I] ABSTRACT
A flexible display is a display which is flexible in nature;
differentiable from the more prevalent traditional flat
screen displays used in most electronics devices. In the
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. [1]
II] INTRODUCTION
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 Samsung’s vice president of
investor relations, Robert Yi, confirmed the
company’s intentions of applying the technology in
handsets and added “… we are looking to introduce
the flexible displays sometime in 2012, hopefully the
earlier part." But however in January 2012 Samsung
acquired Liquavista, a company with expertise in
manufacturing flexible displays, and announced plans
to begin mass production by 2012. During Samsung's
CES 2013 keynote presentation, two prototype
mobile devices that incorporated the flexible
AMOLED display technology were shown to the
public.
On 8 October 2013, the Samsung Galaxy Round was
unveiled as the world's first mobile phone with
flexible display. Featuring a 5.7" touch screen display
made of flexible material, the phone (and the screen)
was curved in shape but the phone itself was solid,
thus not allowing its body or the screen to be
bendable. The Samsung Galaxy Round was 7.9mm
thick and weighed 154 grams. The smartphone ran on
Android 4.3 Jelly Bean operating system and was
sold for $1000 upon release.
However it was not only samsung that announced the
release of a flexible phone. Other major cellular
companies like sony, LG, blackberry etc. also
challenged samsung in the field of producing the first
bendable phone. Small companies like toucho, O2 etc
also joined in the race. Now the wait is for which
company will actually be able to produce the first
flexible touch phone at a feasible value. [1]
III] MANUFACTURING AND PROTOTYPES
Flexible displays using electronic paper technology
commonly use Electrophoretic or Electrowetting
technologies. However, each type of flexible
electronic paper varies in specification due to
different implementation techniques by different
companies. The two designs suggested by two of the
companies are mentioned below. The very first one
was the made by the coalition of the Arizona State
University and HP’s flexible display department. It
was known as the HP and ASU’s e-paper.
6) Solar Powered
The flexible electronic paper display technology codeveloped 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. This
prototype was shown in the University in the year
2008 in a press conference. The following were the
specifications of the prototype: 1) Flexible
Well however this was not the end. LG too self
invited itself in this range and came out with another
prototype of an e-paper with the specifications as
follows:
2) Unbreakable
10) Unbreakable [2]
7) Unbreakable
1) A 6-inch diagonal display size
2) 1024*764 resolution
3) 4:3 aspect ratio
4) TFT based electronic display
5) Allows bending at a range of 40 degrees from the
centre of the screen.
6) 0.7 mm thickness
8) 14 grams weight
9) Could be dropped from a height of 1.5 metres
above the ground with no resultant damage.
3) It could be rolled half a dozen times
IV] ENGINEERING CHALLENGES
Not long after the AU Optronics, a Taiwanese
electronics manufacturing company came out with
another prototype. 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. This prototype offered the following
specifications:
1) A 6- inch diagonal display size
2) High radius of curvature with the maximum limit
of 100 mm.
3) 9:1 high contrast ratio
The basic technology behind the flat displays in
today's phones and tablets is a sandwich of different
material layers. An OLED screen, for example,
typically starts with a glass substrate, on top of which
a circuit containing thin-film transistors and a
capacitor, then the light-emitting OLED layers and,
finally, a transparent, protective layer on top. "A flat
panel display screen is a very complicated product,"
says Nick Colaneri, director of Arizona State
University's Flexible Display Center. Trying to
transform these rigid surfaces into bendable devices
only deepens the complexity. "The support system in
every flat panel display is a piece of glass, and to
make a flexible display, the first thing you have to do
is get rid of the glass."
4) Reflectance of 33%
5) 16 Gray levels
Colaneri says this essentially requires revising the
way companies have built these electronics for years.
Samsung and others have already begun to tackle the
problem. The Samsung prototypes rely on a new kind
of OLED technology in which the rigid glass
substrates are replaced by flexible plastic. Yet relying
on OLEDs also creates additional challenges. OLEDs
are hypersensitive to oxygen and water, which is not
an ideal feature for a consumer product. "They need
to be hermetically sealed," he explains, "and figuring
out a low-cost hermetic seal is a huge problem."
Of course, OLED displays are not the only option.
The basic electrophoretic technology behind E-Inkpowered devices, for example, has always been
flexible. The catch is that this approach will not
achieve the speed or color fidelity of an OLED
display, and the electrodes that turn each of the
millions of microcapsules either black or white have
typically been made using a rigid substrate. Now,
however, E Ink has developed a plastic-based thin
film transistor that can be laminated to its
microcapsule display technology.
Relying on plastic substrates might require some
unfortunate trade-offs. Due to ever-increasing
performance needs, display manufacturers may soon
be shifting from amorphous silicon, the material of
choice for transistors, toward amorphous oxide
semiconductors (AOS) or indium gallium zinc oxide
(IGZO) semiconductors
The switch is due, in part, to the fact that thin-film
transistors that use AOS will be better equipped to
meet the performance needs of tomorrow's devices.
The problem is that AOS transistors run best at
higher temperatures. To be compatible with a flexible
plastic substrate, which is more susceptible to
melting than glass, the process temperature needs to
drop, and that translates into lesser performance. [3]
V]
CURRENT
APPLICATIONS
AND
FUTURE
OLED
Currently, OLEDs are used in small-screen devices
such as cell phones, PDAs and digital cameras. In
September 2004, Sony Corporation announced that it
was beginning mass production of OLED screens for
its CLIE PEG-VZ90 model of personal-entertainment
handhelds. Kodak was the first to release a digital
camera with an OLED display in March 2003, the
EasyShare LS633
Several companies have already built prototype
computer monitors and large-screen TVs that use
OLED technology. In May 2005, Samsung
Electronics announced that it had developed a
prototype 40-inch, OLED-based, ultra-slim TV, the
first of its size. And in October 2007, Sony
announced that it would be the first to market with an
OLED television. The XEL-1 was made available in
December 2007 for customers in Japan. It lists for
200,000 Yen -- or about $1,700 U.S.
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 multidisplay 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.
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. Nokia
envisioned that soon it will make this kind of phone
available to all its users in a period of a couple of
years.
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 LG model of the
television is also 3D compatible. Samsung and LG
too promised that soon after the challenges are
overcome, mass production of these kinds of
televisions will begin and all their users could enjoy
their flexible television experience.
primarily black, for the majority of images it will
consume 60–80% of the power of an LCD.
Research and development in the field of OLEDs is
proceeding rapidly and may lead to future
applications in heads-up displays, automotive
dashboards, billboard-type displays, home and office
lighting and flexible displays. Because OLEDs
refresh faster than LCDs , almost 1,000 times faster,
a device with an OLED display could change
information almost in real time. Video images could
be much more realistic and constantly updated. The
newspaper of the future might be an OLED display
that refreshes with breaking news and like a regular
newspaper, you could fold it up when you're done
reading it and stick it in your backpack or briefcase.
OLEDs are easier to produce than LCDs because
they are essentially made of plastics. They can be
produced into large, thin sheets. It is more difficult to
grow and lay down liquid crystals. [5]
[4]
VI] ADVANTAGES
•
Material properties:
An OLED display is made with plastic and organic
layers. It is thinner lighter and also more flexible than
the rigid crystalline components in a LED or a LCD
display.OLEDs displays are brighter than LEDs
screens which are brighter than LCDs. The
explanation is that LED and LCD require glass for
support, and we know that glass absorbs some light,
and an OLED display do not require glass.An OLED
screen enables a greater viewing angle compared to
LCD, because OLED pixels emit light directly. The
pixel colours appear correct and unshifted, even as
the viewing angle approaches 90° from normal.
Because OLED cells generate light themselves, they
do not require backlighting like LCDs. In addition,
they consume less power than LCDs because most of
the power goes to the backlighting. This is especially
important for battery operated devices like smart
phones. OLEDs can also have a faster response time
than standard LCD screens.
•
Power consumption:
While an OLED will consume around 40% of the
power of an LCD displaying an image which is
•
Production:
VII] DRAWBACKS
•
The Current costs:
OLED manufacturers currently require process steps
that make it really expensive. OLEDs can be printed
on any suitable substrate by screen printing,
theoretically making them cheaper to produce than
LCD or plasma displays. However, the fabrication of
the OLED substrate is more expensive than a LCD,
until mass production methods lower cost through
scalability.
•
Lifespan:
It is the biggest technical problem for this
technology. Common blue OLEDs have a lifetime of
about 14 000 hours to half original brightness when it
is used for flat panel displays. This is lower than the
typical lifetime of LCD or LED technology, around
35 000 hours to half brightness. But for the moment,
OLED technology is less efficient than LCD displays
for flat panel displays like TV screens. However,
some experimental OLEDs can work for over 62 000
hours to half brightness. So this problem is going to
be solved.
•
Water damage:
Water can damage the organic materials of the
displays. Therefore, improved sealing processes are
important for practical manufacturing. Water damage
may especially limit the longevity of more flexible
displays.
•
Outdoor performance:
If you want to test your screen outdoor, you will
probably be surprised. The OLED technology is
affected by the light of the sun and it will be harder to
see good images. Moreover, OLED dispalys can be
damaged by prolonged exposure to UV light. This is
usually avoided by installing an UV filter over the
panel but it reduced the flexibility of the display. [5]
VIII] CONCLUSION
Imagine a world where a 42" flat screen television
can be folded and placed in your pocket, where
curved panes of glass allow advertisements to follow
you everywhere, and where a sheet as thin as a page
of paper can be used as a touchscreen device. In fact,
the glass-making company went so far as to release
an entire video showing how these kinds of
technologies will soon be affecting our lives. Word
has it that Sony is working on a portable folding
OLED screen that is less than a millimeter thick, that
LG is actually manufacturing flexible e-paper
displays that are 19 inches across, and that Samsung
has already created several flexible AMOLED
displays that can withstand heat up to 400 degrees.
With all of these companies investing so much into
flexible displays, it's obvious that they see this
technology taking off.
Many people might actually be wondering of what
would happen to the video quality? Will it be have to
made in a separate way than the normal screen
display? But this is not a problem. In fact designing
videos for flexible screens actually opens up a whole
new world of possibilities. For example, if you had a
screen that was bent into the shape of a ball, you
could put a video of a spinning basketball or world
globe inside. Flexible video surfaces would also
make it possible to put moving ads in places that
were once the territory of print. The inside of public
transportation vehicles and domed ceilings could
show video advertisements. Even windows on
buildings could go from displaying the wonders of
the great outdoors to the wonders of a new product.
No matter what, all of these things could mean more
paying jobs for all those involved in making video. [6]
IX] ACKNOWLEDGMENT
I take this opportunity to express my profound
gratitude and deep regards to my guide Mr.
Sukhwinder Singh for his guidance and constant
encouragement throughout. The help and guidance
given by him shall carry me a long way in the
journey of my life.
Lastly, I thank the almighty, my parents for their
blessings and the opportunity to make this review
possible.
X] REFERENCES
[1]http://en.wikipedia.org/wiki/Flexible_display#Samsung
[2] http://goodereader.com/blog/e-paper/samsung-shows-off-4-5inch-flexible-amoled-display
[3]
http://flexiblescreen.wikispaces.com/Advantages+and+Drawbacks
[4] http://electronics.howstuffworks.com/oled6.htm
[5] http://www.videomaker.com/videonews/2011/08/how-the-ageof-flexible-televisions-will-affect-video
[6] http://cacm.acm.org/magazines/2013/6/164606-the-future-isflexible-displays/fulltext
.