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VOLUME -24 NUMBER 2
Publication Date: 02/1/2009
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HP and Arizona State U. Demo Flexible Paperlike Displays
Palo Alto, CA and Phoenix, AZ — Digital displays that can be rolled, folded like a newspaper, or bent to fit around a building or car are finally poised to make the leap from the lab to production on a mass scale. HP and the Flexible Display Center (FDC) at Arizona State University (ASU) have developed the first prototypes.

These affordable, flexible electronic displays are paper-like computer displays made almost entirely of plastic. This technology enables displays to become easily portable and consumes less power than today's computer displays. Popular applications for the technology could include electronic paper and signage.

The production feat is regarded as a milestone in the industry's efforts to create a mass market for high-resolution flexible displays. Plus, from an environmental standpoint, the displays leapfrog conventional display processes by using up to 90 percent less materials by volume.

Electronic Paper
Flexible screens — sometimes referred to as "electronic paper" — are made by layering stacks of semiconductor materials and metals between pliable plastic sheets. The stacks need to be perfectly aligned and stay that way — a trick that's tough to pull off 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 technique also allows the screens to be manufactured in rolls, rather than individual sheets, making their production cost-effective for the first time. Mass production of such displays could enable a new generation of smartphones, laptops and other mobile electronic devices, as well as the long-dreamed-of electronic newspaper and wall-sized flexible signage.

Mass production of such displays can enable production of notebook computers, smart phones and other electronic devices at much lower costs since the display is one of the most costly components. The Flexible Display Center was established in February 2004 with a 10-year cooperative agreement with the U.S. Army Research Laboratory and $43.7 million in funding for the first five years. The Army's interest in flexible displays is as an enabling technology that can improve performance of its people on the ground by providing instantaneous information to even the most remote of locations. But developing flexible displays has meant reworking them from the ground up. In order to make flexible displays — flexible enough to be body contouring or even folded or rolled up — FDC researchers and their industrial partners have developed new display designs, worked with new materials for the displays and associated electronics, and re-worked existing manufacturing methods.

Glass Ceiling
A major step towards flexible displays is to get the glass out. Today, all conventional displays — from cell phones to desktop computers — are manufactured on thin glass. It's the reason why the displays are so vivid and reliable. It's also the reason why they are rigid and fragile.

Because flexible displays are so different from traditional displays, entirely new methods of manufacture (and modifications to present semiconductor methods) are needed to build them. With the goal to deliver rollable displays, the electronics behind the display must be flexible too so they need to be manufactured on plastic or thin metal foil substrates with new thin film transistor technologies.

The unbreakable displays have been created by the FDC and HP using self-aligned imprint lithography (SAIL) technology invented in HP Labs, HP's central research arm. SAIL is considered "self aligned" because the patterning information is imprinted on the substrate in such a way that perfect alignment is maintained regardless of process-induced distortion.

SAIL technology enables the fabrication of thin film transistor arrays on a flexible plastic material in a low-cost, roll-to-roll manufacturing process. This allows for more cost-effective continuous production, rather than batch sheet-to-sheet production. "The display HP has created with the FDC proves the technology and demonstrates the remarkable innovation we're bringing to the rapidly growing display market," said Carl Taussig, director, Information Surfaces, HP Labs. "In addition to providing a lower-cost process, SAIL technology represents a more sustainable, environmentally sensitive approach to producing electronic displays."

Flex Display Production
The first practical demonstration of the flexible displays was achieved through collaborative efforts between the FDC and HP as well as other FDC partners including DuPont Teijin Films and E Ink. To create this display, the FDC produces stacks of semiconductor materials and metals on flexible Teonex® Polyethylene Naphthalate (PEN) substrates from DuPont Teijin Films.

HP then patterns the substrates using the SAIL process and subsequently integrates E Ink's Vizplex imaging film to produce an actively addressed flexible display on plastic. E Ink's Vizplex bi-stable electrophoretic imaging film enables images to persist without applied voltage, thereby greatly reducing power consumption for viewing text.

"Producing a photolithography-free, flexible active-matrix display is an excellent example of the Flexible Display Center's world-class development and manufacturing infrastructure," said Shawn O'Rourke, director, Engineering, Flexible Display Center at Arizona State University. "It demonstrates how multiple industry partners can collaborate on innovative solutions, including roll-to-roll compatible technology that addresses the rapidly growing market for flexible electronics."

"Flexible electronic displays are playing an increasingly important role in the global high-tech industry, serving as the crucial enabling technology for a new generation of portable devices, including e-readers and similar products designed to combine mobility with compelling user interfaces," said Vinita Jakhanwal, principal analyst, Small and Medium Displays, iSuppli. "We expect the flexible display market to grow from $80 million in 2007 to $2.8 billion by 2013. The Flexible Display Center at Arizona State University is a key participant in helping to develop the technology and manufacturing ecosystem to support this market."

The FDC is a government/industry/academia partnership that's advancing full-color flexible display technology and fostering development of a manufacturing ecosystem to support the rapidly growing market for flexible electronic displays. FDC partners include many of the world's leading providers of advanced display technology, materials and process equipment. The FDC is unique among the U.S. Army's University centers, having been formed through a 10-year cooperative agreement with Arizona State University in 2004. This adaptable agreement has enabled the FDC to create and implement a proven collaborative partnership model with more than 20 engaged industry members, and to successfully deploy world-class wafer-scale R&D and GEN-II display-scale pilot production lines for rapid flexible display technology development and manufacturing supply chain commercialization. More information about FDC is available at
http://www.flexdisplay.asu.edu.  

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