Improving Flexibility

The first affordable, flexible electronic display was recently unveiled by Hewlett-Packard and the Flexible Display Center (FDC) at Arizona State University. This new paper-like computer display is made predominately of plastic, which makes the device portable and more energy efficient than most conventional computer displays. Creation of the high-resolution flexible display marks a milestone for both HP and the FDC: The opportunity to manufacture mass-market products.

“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, while providing a lower-cost process,” says Carl Taussig, director of the Information Surfaces Lab at HP Labs.

Taussig says the self-aligned imprint lithography (SAIL) technology represents a more sustainable, environmentally sensitive approach to producing electronic displays.

Flexible electronic display technology is creating new solutions in the global high-tech industry, including a new generation of portable devices, such as e-books and e-readers. E-readers could have a significant influence on a variety of markets. For instance, they can be used by doctors in hospitals for storing and retrieving patients’ medical records, and engineers can use them as digital manuals, replacing heavy, expensive and space-consuming paper manuals.

E-readers also have the advantage of being interactive. Searching for a word in a book or a manual is quite complicated without an index, and even with a good index it can be hard. An e-reader can easily search text documents, and some e-readers also allow adding notes using a touch screen, which further extends their usefulness.

Vinita Jakhanwal, principal analyst for small and medium displays at iSuppli, expects the flexible display market to grow from $80 million in 2007 to $2.8 billion by 2013. Jakhanwal adds that the Flexible Display Center at ASU is a key participant in helping to develop the technology and manufacturing ecosystem to support this market.

The new flexible electronic display technology could be applied to electronic paper and signage. Mass production could enable displays to be used in notebook computers, smart phones and other electronic devices at a much lower cost than conventional display devices. Another major advantage is that these flexible displays use only 10 percent of the materials required by current display production, saving the environment and creating lighter devices for our pockets.

The process of manufacturing the display starts with FDC producing stacks of semiconductor materials and metals on flexible Teonex, a polyethylene-naphthalate (PEN) substrate. Using the patented SAIL process, HP patterns the substrates and consequently incorporates E Ink’s Vizplex imaging film to create an actively addressed flexible display on plastic. The Vizplex is a bi-stable electrophoretic imaging film, which allows images to be continuously displayed even when no voltage is applied. This considerably lessens the power consumed by the display, which in turn reduces electrical costs and provides for much longer battery life for portable devices.

The SAIL process was invented by HP Labs and was paramount to the displays’ success. The “self-aligned” element in this method is derived from patterning information, which is imprinted on the substrate in such a way that precise alignment is preserved, regardless of process-induced distortion. SAIL technology helps foster the manufacturing of thin film transistor arrays on a flexible plastic material in a low-cost, roll-to-roll manufacturing process. This allows for a more commercially continuous production, rather than batch sheet-to-sheet production.