The Daily Flicks: Morphing ink may bring video to newspapers
Peter Weiss
Imagine opening the newspaper and seeing a full-color, video clip of a battle
or sports match. That's the sort of vision that drives developers of electronic
paper. Even though a black-and-white version that can display static images
remains in development, two new approaches offer the prospects of video and
bright color.
Electronic paper is a display technology akin to conventional paper but in
which the words and images can be changed at will (SN: 6/20/98, p. 396: http://www.sciencenews.org/sn_arc98/6_20_98/bob2.htm).
Until now, most developers have rolled out prototypes that rewrite images too
slowly for video.
Among many e-paper schemes is that of E-Ink of Cambridge, Mass. The company
encloses white and black particles inside an array of liquid-filled
microspheres. Electrically controlled spheres collectively serve as a pixel in
an image. A voltage across a microsphere induces the particles to migrate in
opposite directions so that one face of the sphere becomes black and the other
white. Reversing the voltage flips the pixel to the opposite configuration.
In the Sept. 25 Nature, Robert A. Hayes and B. Johan Feenstra of
Philips Research in Eindhoven, the Netherlands, describe a new type of e-paper
pixel. It looks dark when covered by a thin film of colored oil. But when a
voltage sweeps the oil into a corner, a bright white surface appears. Pixels
one-quarter millimeter on a side can switch between dark and light in less than
15 milliseconds?fast enough for standard video signals.
By building a more complicated pixel structure that includes filters and
multiple oil layers, the researchers have made elements of e-paper that can
generate a wide range of colors with exceptional brightness.
Although the display depends on liquid spreading over surfaces, it's stable
against tipping or jarring, notes Hayes. That's because the fluids are held in
place by capillary forces that overpower gravity and other mechanical forces.
Claiming to have already tested the same technology, physicist Joseph M.
Jacobson of the Massachusetts Institute of Technology and a cofounder of E-Ink,
remarks that the Philips technology harbors a serious flaw: The pixels require
continuous power to maintain an image because the oil recoats the pixel surface
as soon as the electricity is shut off. Consequently, batteries might run down
quickly.
The power issue is a real one, Hayes acknowledges, but it's most problematic
for static images, which last for seconds or longer. He says, "We're focusing on
video-speed applications, where we have to [repeatedly and rapidly] refresh the
screen, anyway."
By next spring, Jacobson says, E-Ink will probably unveil its own full-color
e-paper that can change fast enough for video. Unlike the approach that the
Philips' team is taking, the E-Ink technology consumes no power when the image
is static, Jacobson says.
Last week at the International Display Research Conference in Phoenix, a
Canadian research team reported yet another potential way to achieve color video
on e-paper. This one relies on particles that move through a liquid. The
distance the particles need to migrate is only a small percentage of the
distance required in E-Ink's microsphere technology. Shorter distances translate
into faster switching, a key to creating moving images, says team leader Lorne
A. Whitehead of the University of British Columbia in Vancouver.
The video e-paper race is on. Paul S. Drzaic, former director of technology
at E-Ink and now with Alien Technology in Morgan Hill, Calif., says that which
players come out on top will depend on "how well they solve the problems that
always pop up."
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References:
Hayes, R.A., and B.J. Feenstra. 2003. Video-speed electronic
paper based on electrowetting. Nature 425(Sept. 25):383-385. Abstract
available at http://dx.doi.org/10.1038/nature01988.
Mossman, M.A. . . . and L.A. Whitehead. 2003. A high
reflectance, wide viewing angle reflective display using total internal
reflection in microhemispheres. 23rd International Display Research Conference.
Sept. 15-18. Phoenix, Ariz. Abstract available at http://www.sidmembers.org/source/papers/uploadedpapers/idrc2003_P-23.pdf.
Further Readings:
Gorman, J. 2001. New device opens next chapter on e-paper.
Science News 159(April 28):262. Available at http://www.sciencenews.org/20010428/fob5.asp.
Peterson, I. 1999. Electronic ink debuts in store signs.
Science News 155(May 29):347. References and sources available at http://www.sciencenews.org/sn_arc99/5_29_99/note8ref.htm.
______. 1998. Rethinking ink. Science News 153(June
20):396-397. Available at http://www.sciencenews.org/sn_arc98/6_20_98/bob2.htm.
Sources:
Paul Drzaic
Advanced Development Programs
Alien
Technology Corporation
Morgan Hill, CA 95037
B. Johan Feenstra
Philips Research Eindhoven
Prof.
Holstlann 4
5656 AA Eindhoven
The Netherlands
Robert A. Haynes
Philips Research Eindhoven
Prof.
Holstlann 4
5656 AA Eindhoven
The Netherlands
Joseph Jacobson
MIT Media Lab
Building
E15
Cambridge, MA 02139
Lorne A. Whitehead
Department of Physics and
Astronomy
University of British Columbia
Vancouver, BC V6T
1Z1
Canada
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