The Flexible-Display Vision

by Chuck Spear

The vision of the flexible flat-panel display (FPD) entered popular consciousness in late 2002 when a prototype roll-up display from Universal Display Corp. was seen by millions on the CBS Evening News, in Time and Newsweek magazines, and elsewhere. The age of the flexible FPD is not yet upon us, but it is the subject of an extraordinarily energetic quest by many companies and institutions worldwide. But what exactly is a "flexible" FPD, and what are the perceived benefits that have so many companies, institutions, and governments sinking large amounts of dollars and time into the quest?

The term "flexible FPD" is being applied to a broad range of capabilities, with different levels of flexibility presenting a diversity of design challenges and potential benefits. In its simplest sense, flexibility refers to the resistance to physical shock that will allow an FPD to take a hit and keep on working, rather than shattering. One step beyond that is the display that can be curved to conform to a non-planar surface when it is integrated into a product – a "bend once" FPD that can endure a certain degree of curvature without failing. Beyond these are the full-fledged flexible FPDs that can actually be rolled up by the user or folded up and slipped into a pocket.

Clearly, "flexibility" encompasses a broad range of requirements and challenges for the displays themselves, as well as for display materials and components such as substrates, conductive coatings, encapsulation, and circuitry. There are candidate technologies being explored all along the flexible-display chain.

The Flexible Challenge

The quest for flexible FPDs is not a new one. Plastic-substrate LCDs tested the market in both the 1980s and 1990s and came up wanting, and the problems that plagued these early efforts still challenge developers today. Moreover, the more ambitious flexible-display development of today is greatly complicating the quest, in some cases requiring new materials, new manufacturing processes, new equipment, and new display designs. Steve Quindlen, President of DuPont Displays, said, "A lot of basic science has to be resolved."

The quest for the flexible display also suffers from its multi-disciplinary nature. Expertise is required in chemistry, physics, optics, and mechanics, for example, as well as in different manufacturing technologies. If there is an upside to this, it is that the quest can draw on existing experience in previously unrelated industries. Printing equipment for plastic consumer packaging, for example, can be modified for printing some or all of an FPD.

With the requirement that so many diverse resources be brought to bear, it is no wonder that the quest for flexibility has become a highly cooperative venture in which strategic development relationships are common. Cooperative ventures are being encouraged not only by the difficulties of the quest, but also by a dismal economic environment in which sharing investment and risk is essential.

A Long and Winding Road

The flexible-FPD quest is likely to be a long one. Flexible displays appear to be on the roadmap of every OLED and electronic-paper company, but they also appear to be on nobody's front burner. "We are only at the beginning of the journey," said Robert Pinnel, Chief Technology Officer of the U.S. Display Consortium.

It is likely that members of the FPD industry will find ways to solve the technical problems of producing flexible displays. But while they are working at it, there is one big unanswered question echoing throughout the community: "What's the killer app?" Display consultant Stewart Hough, formerly of Cambridge Display Technology, acknowledges a desire in the marketplace for "thinner, lighter-weight products," but he notes that "the market paradigm is not fully established and the value proposition is not totally understood, so research continues."

The Market

The identification of key markets is critical. With only a 5-year window to prove itself and gain additional funding, a flexible FPD must attract early adopters of technology to survive. We believe flexible FPDs that create new markets will do that and achieve the critical mass for success, but flexible FPDs for replacement markets should take much longer to diffuse.

All in all, the market for flexible displays and electronics could reach $400–500 million by 2010. The near-term opportunities include radio-frequency identification (RFID) tags, smart cards, and electronic signage, followed by medical devices, flexible keyboards, and various types of wearable products.

However long it takes developers to achieve each piece of the flexible-display vision, the stages on the roadmap seem fairly clear. What is unclear is how long it will take for the roadmap to unfold.

In the near term, flexible FPDs are likely to bring perceived value to common display applications in the form of greater impact resistance, thinner profile, and lower weight. Perhaps the long-awaited smart card with a display readout will finally arrive and the infrastructure necessary to take advantage of it will proliferate. Perhaps flexible displays will find a home in some niche application such as portable, industrial, military, or even educational computers for operating environments where extreme ruggedness is valued. Or perhaps conformal displays will become de rigueur in stylish LCD watches.

Then, a bit down the road, flexible displays could motivate the development of flashy consumer products by designers able to pay for the design freedom to move beyond today's rigid, rectangular displays. The floodgates may then open, with new generations of FPD products flowing with clever new types of designs none of us can yet anticipate. Later still comes the rolling and folding; and, perhaps beyond that, the interactive environments with omnipresent display technology. Meanwhile, flexible-display technology, already being used in the form of thick-film electro-luminescent (EL) backlights, also promises to contribute to general-purpose lighting applications.

The ultimate promise of the flexible FPD is an economic one: If continuous roll-to-roll web processing can replace the batch processing of glass-based displays, extraordinary production economies accrue, as well as the potential for very large displays. That, some visionaries say, could make fabricating a display as easy as printing a newspaper – and almost as inexpensive. •