http://www.tradingmarkets.com/.site/news/Stock%20News/2064767/
RICOH USES INKJET METHOD TO FABRICATE FINE-RESOLUTION E-PAPER
TOKYO,
Dec 2008 – Ricoh Co.has developed a process using inkjet printing
technology to fabricate an electronic paper that offers fine resolution.
Display
resolution has been a problem with e-paper made using inkjet printing
techniques, but Ricoh has prototyped a 3.2-inch e-paper display that is
0.3mm thick, bendable and has a resolution of 160 pixels per inch. That
resolution stands on par with e-paper made using semiconductor
manufacturing techniques.The advantage of inkjet printing is that
e-paper can be made for half the cost of methods that depend on vacuum
chambers and other expensive equipment.Ricoh hopes to use its
technology to enter the market for e-paper in three to four years with
products for e-books and advertising media.
The e-paper is
fabricated on a bendable plastic base. To trace the pattern for the
transistors and electrodes, ultraviolet light is shined onto a special
resin coated over the plastic base. This resin becomes hydrophilic when
exposed to UV rays, so only at those places will silver adhere to form
electrodes when a silver solution is inkjet-printed onto the base. The
precision placement of the electrodes is what boosts the resolution of
the e-paper.Next, the transistors are fashioned from an organic
semiconductor material, then microscope capsules containing
positive-charged black particles and negative-charged white particles
are spread down for the pixels. By controlling voltage to the
transistors, each pixel can flip between black and white for text and
graphics displays.