Race for Color Video E-readersDecember 21, 2009
An alternative way of creating a photonic display is to use self-assembling copolymers that swell in response to chemicals. Yet another approach is based on dielectrophoresis, where Kodak, for example, electrically manipulated particles suspended in a fluid. Of course here the spacing is manipulated whereas in electrophoretic displays the field moves particles to the surface.
At Kodak, David Snoswell developed faster photonic crystal systems in this manner with "sub millisecond switching rates" before the work was terminated and he is now at the University of Cambridge in the UK. He says, "You induce an electric dipole in the particles with an electric field. Like little bar magnets, they all line up." Sadly most devices relying on movement in a fluid such as glycerine tend to be slow, and, at low temperatures, have sticky images and even freeze.
Switching at sub-microsecond times is achieved with fast photonics and that is more than adequate for video with fast photonics, however. With photonic crystals, the problem is far less severe because much smaller distances are involved. In the case of electrophoretic displays, Bridgestone, the Japanese car tire manufacturer has now demonstrated a version with particles that work in air giving video speed. Brightness and other challenges are being tackled before commercialisation.
Although Professor Chigrinov at Hong Kong University of Science and Technology and others are starting to print LCDs on flexible substrates that may be very low in cost and tightly rollable, the Canadians and others claim the better images and faster switching of their approach is superior. By contrast, E-Ink, now a subsidiary of e-reader manufacturer Prime View International in Taiwan, has only announced 50 millisecond switching, the equivalent of 20 frames per second and inadequate for video. But what do they have in the laboratory?
In yet another very different approach, electrowetting enthusiasts Liquavasta, now under new ownership and management, has changed course to prioritise e-reader displays with a target of marketing something in three years. ADT in Germany also makes electrowetting displays. The argument for electrowetting is that it already gives brilliant colors and video speeds and Liquavista appears to be three years from having a color video display for e-readers. It will take more current than today's E-Ink monochrome e-readers. Perhaps it will be bistable: ADT claims to use the technology in a bistable version though it is not prioritising e-readers and its displays are very basic so far.
Certainly there is everything to play for and no clear winner anywhere in sight. The situation is complicated by the many candidates for the color, video e-reader display and the uncertainty about whether such aspects as bistability, transparency and ability to be rolled tightly will be important in the marketplace.
For now, IDTechEx will only hazard that more power will probably be needed for color and video, adding weight in the form of bigger batteries and probably energy harvesting. The next ten years will see color video e-readers creating a higher cost up-market and not displacing today's monochrome bistable e-readers for some time.