Tim Green
Associate Director,Visual Communications Technologies, CAP Ventures, USA.
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Currently, a race is on between
companies and between technologies
to replace paper and film by adding
functionality to books, newspapers and signs
while not reducing the “viewability” and ease
of use that these traditional medium offer.
Electronic ink and electronic paper promise to
make a great impact on the bottom line of
writers, retailers, and publishers. In the long
term, the potential of these technologies is
clearly a threat to some paper and film-based
products and processes. The purpose of this
article is to highlight some of the leading
vendors, technologies and applications in the
electronic ink and electronic paper market.
Definition
It may be helpful to include here a basic
explanation of the various technologies. Gyricon’s
(Ann Arbor, MI, USA) electronic article is a product
made of magnetic balls, each measuring one-tenth of
a millimeter that are half-black and half white,
embedded in a thin film. When an electric charge is
applied to the film, the balls rotate so that either the
black or white side is in the “up” position. E Ink’s
(Cambridge, MA, USA) product involves similarly
sized, transparent spheres containing black oil and
dozens of tiny white beads that, through an electric
charge, either float to create a white image or
submerge to appear dark.
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This is much different than LCD display technologies, which operate as a light “valve”, blocking light or allowing it to pass through. An image in an LCD is formed by applying an electric field to alter the chemical properties of each LCC (Liquid Crystal Cell) in the display in order to change a pixel's light absorption properties.
EI/EP vs. LCD
There are advantages and disadvantages to both EI/
EP and LCD technologies. While the leading suppliers
and innovators in these areas are working out the
disadvantages, it is useful to discuss the strengths and
weaknesses of each here.
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The glaring weakness of electronic ink and electronic paper, in their current iterations, is the lack of colour output. Since the two main products both use bi-chromal balls in their displays, they both can only display one colour at a time. Another problem with EI/ EP is that it is such a new product, even though there are some industry heavyweights behind it, that manufacturing capacity is unknown. On the other hand, the strengths of EI/EP are that they require very little power to make them work and they are thin and flexible.
The limitations of LCDs are that they are
expensive and that they require a lot more power (as
opposed to EI/EP) to make them work. However, there
have been recent breakthroughs in LCD technology
that now allow them to effectively produce scalable
colour displays, using graphics and moving images,
so well that they are considered an eventual
replacement for CRTs (cathode ray tubes), which are
the display technology for most computer monitors
and televisions today.
Trends in EI/EP & LCD
Some key product trends are clear:
Higher Screen Resolution - EI/EP and LCD
providers are trying to develop displays that are easier
on the eyes than current paper and screen offerings.Advanced electronic
paper sample resolutions equal
a standard laser printer between 300 and 600 dpi. LCD
technologies are moving a little faster, having
improved LCD screen resolutions beyond typical CRT
capabilities.
Lower Power Requirements - A major benefit of
both EI/EP and LCD technologies are that they require
much less power than CRTs.
Colour - Development of colour EI/EP is an
unrealized goal so far, making this one area where
LCDs hold a real advantage; LCDs are capable of
more than just color displays, they can present scalable
displays that produce full motion video with wide
viewing angles.
Wireless - The makers of electronic ink and electronic
paper are smartly focusing on wireless technology.
The ability to wire-lessly transmit a message to be
displayed on the electronic paper or tablet is an
important part of the adoption of these technologies
for early applications.
Other Display Technologies
As much as EI/EP & LCD suppliers position their
technologies as the display types of the future, there
is a growing threat to these companies from other
display technologies. While Gyricon and E Ink are
working on ways to produce full color displays on a
paper-like substrate, these new technologies can
produce a full color display that is as thin as a dime.
Cambridge Display Technologies, (Cambridge,
England) and Kent Displays, (Kent, OH, USA)
meanwhile, are working on ways to further reduce
power consumption. Some of these new technologies
operate on less voltage than it takes to run a flashlight.
OLED
OLED (organic light-emitting diode) is not what you’d
call a futuristic technology, not because it is not highly
advanced, but because it is already being used. The
most advanced OLED technology comes out of a
collaboration between Sanyo and Kodak.
Unlike traditional LCDs, OLEDs are selfluminous
and do not require backlighting.
This
eliminates the need for bulky and environmentally
undesirable mercury lamps and yields a thinner, more
compact display. OLEDs have a wide viewing angle
(up to 160 degrees), even in bright light. Their low
power consumption (only 2 to 10 volts) provides for
maximum efficiency, and helps minimize heat and
electric interference in electronic devices.
The basic OLED cell structure consists of a stack
of thin organic layers sandwiched between a
transparent anode and a metallic cathode. The organic
layers comprise a hole-injection layer, a hole-transport
layer, an emissive layer and an electron-transport layer.
When an appropriate voltage is applied to the cell,
the injected positive and negative charges recombine
in the emissive layer to produce light. The structure of the organic layers and the choice of anode and
cathode are designed to maximise the recombination
process in the emissive layer, thus maximising the light
output from the OLED device.
GH-PLCDs
Another new display technology comes from Dai-
Nippon Printing (DNP) Company’s Central Research
Institute. DNP’s technology, called Guest Host
Polymer Dispersed Liquid Crystal (GHPDLC)
is sort
of a hybrid between E Ink’s or Gyricon’s technology
and Kent Display’s technology. Dai Nippon’s
Thermal/Electric Rewritable Digital Paper uses a
bistable LCD called Smectic A (SmA) on its rewriteable
paper. Here is how it works:
Smectic A is a bistable LCD, which means that it
holds its state long after the charge or heat is removed.
In DNP’s GHPDLC
rewriteable medium, a special
light absorbing dye is used. The “Guest” dye
molecules are oriented in the medium by the bistable
“Host” liquid molecules to display
and retain images.
To create the critical
GH-PLDC layer, droplets of
SmA liquid crystal are dispersed in a polymer binder.
The light absorption properties of the dye give this
medium the ability to display colour images. When
the alignment of the SmA liquid crystal in the droplet
is changed by adding electrical or thermal energy, the
alignment of the dye is similarly changed.
DNP’s rewriteable medium is produced by coating
the GH-PDLC layer on a conductive layer which is
sandwiched by a substrate and a protective layer.
Images are electrically recorded on this film by
controlling the orientation of the SmA liquid crystals
in the GH-PDLC layer.
The imaging system of DNP’s rewrite-able media
includes a thermal writing device and an electrical
erasing device. The thermal energy changes the
alignment of the SmA liquid crystals in the PDLC
film form a light emissive state to a light blocking
state, resulting in what appears to be a printed image.
The erasing device simply changes the alignment of
the SmA crystals back to the light emissive state which
clears the medium for rewriting.
DNP has successfully applied its technology to
plastic cards where the displayed information changes
frequently. The company has also developed printers
that could use the media with personal computers.
Once printed on, the media can be fed through the
erasing device and reloaded into the printer’s paper
tray. DNP envisions that its rewriteable paper could
be used for displaying “printed” newsletters and news
summaries directly from the Internet.
Magink
One of the newer companies to enter the market is New
York-based Magink. Magink, which is only 3 years old,
has developed a full colour display which it is targeting
at the billboard market. Some may remember Magink as it was formerly known, E-Magin Ltd, which was
one of the first to license Kodak’s OLED technology.
Magink’s technology is based on “electronic ink”,
which is a chemical substance that produces colour
images when digital impulses are sent through it.
Commercialisation
It will be very interesting to see how rapidly some of
these technologies come to market especially given
the licensing agreements
that are now in place. For
example, E-Ink has agreements with Roayl Phillips
and Toppan Printing Company, Gyricon has an
agreement with Array Marketing/Thomson Leeds,
CDT has license agreements with partners such as
Philips, Uniax, Hoechst, DuPont, Seiko, Epson and
Delta Electronics. Kodak has license agreement with
Sanyo, Varitronic, Pioneer, and Samsung. Magink has
agreements in place with Mitsubishi Electric as well
as pilot programs in place with Clear Channel and
Pattison Outdoor.
Conclusions
The increased timeliness, ability to change the message,
and in some cases, the economics of the new display
technologies makes them a compelling answer for
some early adopters today. When the technical
challenges surrounding colour and resolution have
been met and the questions of mass production of these
materials has been answered, devices employing these µ
advanced display technologies may be as common as
cell phones and laptop computers are today.
It is evident from an analysis of the various
technologies that they are on a collision course. All
have targeted graphic displays such as in-store signage
and out-of-home advertising, and consumer electronic
devices as the ultimate destination. In the big picture,
there is unlikely to be a clear cut “winner” among
these display technologies, more likely, the one that
best fits the particular applications and best meets the
needs of specific products will emerge, the “winner”
to be decided on a case-by-case basis.
Footnote:
The explanation of how ONP’s GH-POLC process
works was abstracted from “The Future Print Media
Journal”, from Kent State University, 4/99,
Information on Kodak’s OLEO technology was
abstracted from Kodak’s web site atwww.kodak.com
