Field-Emission Displays Get a Second Wind
Will resurgent research and development make FEDs a flat-panel phoenix, or will developers get burned again?
1 October 2003--The field-emission display, known as the FED, was the darling of the flat-panel display industry in the 1990s. Replacing the single, large hot cathode of a cathode-ray tube (CRT) with tiny cold-cathode emitters, hundreds or even thousands of such cone-shaped ”microtips” for every display pixel, the FED promised to bring CRT-like performance to a flat-panel arena that was hungry for better visual quality. But it wasn't too long before the promise fizzled and FEDs looked like just another over-hyped might-have-been technology.
Just as it seemed that FED pixels were flickering their last, though, some of the very same companies that got burned last time around began reviving their R&D efforts and promising prototypes. Engineers from these companies and others claim that a second generation of technology embodies fixes to the many flaws that killed its predecessor while delivering both visual quality and the potential for very low manufacturing costs that are similar to those for CRTs.
Companies are prototyping both large and small format displays, tapping a variety of materials, emitter structures, and overall architectures. Most avoid the complex semiconductor-like lithographic processes needed to make the first generation of FEDs, opting instead for simple manufacturing techniques that promise both low cost and easy scale up to large sizes.
But, as industry observers point out, we've heard such promises before.
Death of a technology
According to inside sources, first-generation FED developers failed to understand the difficulties involved in bridging CRT principles over to a flat-panel structure. Many variations were tried out, but the bottom line, according to Barry Young, vice president at flat-panel display market research firm DisplaySearch (Austin, Texas), was that all were plagued by lifetime issues--the displays just didn't last. The main culprits were particles and gases trapped in the FED during manufacture and released when electrons struck various internal display elements, undermining the internal vacuum and poisoning the pixels.
The majority of the first FED developers took a wrongheaded approach, says Tom Holzel. Now an independent product-positioning consultant, Holzel has been involved with the FED efforts of both Raytheon Co. (Lexington, Mass.) and PixTech Inc. (Rousset, France), as well as with second-generation FED company Printable Field Emitters Ltd. (Chilton, Oxfordshire, UK). Most, he said, looked at problems from a semiconductor rather than a CRT point of view.
Motorola Inc. (Schaumburg, Ill.), for one, conducted an ambitious FED program in the 1990s. Kicking off a small FED research project early in the decade, the company subsequently bought a license from PixTech, which held the basic FED patents developed at LETI (Laboratoire d'Electronique de Technologie et d'Information, in Grenoble), a research laboratory of France's national energy commission. In 1995, Motorola established an FPD division and, in early 1998, it completed a 25 500 square-meter pilot production facility and demonstrated its first FEDs. By mid-1999, however, the company started scaling back its FED activity, effectively gutting it in mid-2000. (PixTech, the only company to ever ship production FEDs, shut its doors in mid-2002 for want of funding.)
”Motorola underestimated the complexity of developing a new display technology,” says a former member of the company's FED effort who requested anonymity. What's more, its business model appears now to have been flawed. Says DisplaySearch's Young: ”With the required lithographic processes [for the cathode emitters], the net result was that the equipment and factories were going to be every bit as expensive as for LCDs [liquid-crystal displays]”--which, together with plasma units, are FEDs' main competition.
Rising from the ashes?
A second generation of FEDs is now stirring up as much excitement as the first, but whether its advocates' claims are hype or deliverable promise has yet to be seen
A large amount of R&D on FEDs is being conducted today by such companies as Delta Optoelectronics, Fujitsu, Hitachi, LG Philips, Mitsubishi, Motorola, Pioneer, Samsung, Stanley Electric, and a number of start-ups, much of it focused on nanotubes. To help fuel the second-generation FED quest, Holzel noted that the Japanese and Taiwanese governments are both funding national FED programs, ”with an emphasis on [carbon nanotubes] for large TVs.”
Kim Allen, director of technology and strategic research at another flat-panel display market research firm, iSuppli/Stanford Resources (El Segundo, Calif.), notes that the potentially wide-ranging application of carbon nanotubes is making related FED research more fundable. In addition to nanotubes, the emitter technologies being developed for next-generation FEDs include variations on the traditional Spindt microtip FEDs, which were originally developed at SRI International (Menlo Park, Calif.), and a variety of styles of planar emitters.
All the FED wannabes, of course, claim to sidestep the difficulties of the first generation. The technologies used by Canon Co. (Tokyo) and Great Britain's Printable Field Emitters, for example, as well as nanotubes developed by the Display Lab at Samsung Advanced Institute of Technology (Seoul, South Korea), rely primarily on low-cost printing techniques. Matsushita Electric Industrial Co. (Osaka, Japan), on the other hand, fabricates displays using a primarily electrochemical process that includes very little of the complex photolithographic processes used for first-generation displays. And Printable Field Emitters claims its FEDs are immune to the contamination problems that plagued the first devices. All the contenders promise the eventual capability of manufacturing large displays at low cost. Promise is not proof, however; nor is the laboratory the real world, and it will be some time before the second-generation FED story unfolds.
For the moment, the one product containing nanotube FEDs is a large single-pixel display module from ISE Electronics Corp. and Noritake Itron Corp. (both in Ueno, Japan), which is meant for huge public infotainment systems in stadium and similar venues.
Two companies reportedly have FED lines in place: Sony Corp. (Tokyo), which holds manufacturing rights to the technology of former development partner Candescent Technologies Corp. (a company in Los Gatos, Calif., that shut down manufacturing operations in 2001), and Futaba Corp. (Mobara City, Japan), which started sampling monochrome FEDs in early 1997 but never fielded production displays.
Having been burned with first-generation FEDs, display analysts are generally cautious about the prospects for the next round. Alfred Poor, a flat-panel display analyst and consultant based in Perkasie, Pa., sees the resurgent interest in FEDs as ”a pleasant surprise.” According to DisplaySearch's Young, the market for large flat-panel TVs will grow rapidly in the next few years, but if LCD and plasma are the technologies available, units will cost US $1000 or more. In contrast, he says, equivalent FED TVs could be priced at $500, ”or even less, but there are still a fair number of problems to be worked out.”