Displays to define Net appliances

he first generation of Internet appliances will do quite nicely with passive liquid-crystal displays (LCDs), thank you, but the picture will grow more complicated with coming generations as active-matrix (AM) LCDs get into the game.

Farther out on the horizon, there's more than a handful of alternative display technologies in development that will vie for display slots in appliances. Some of these may succeed, but only if their purported advantages pan out, and only if the enigmatic product category of Internet appliances (IAs) evolves into applications where these advantages have perceived value.

Some IA applications will require excellent video performance, for example, while others will demand the ultimate in color fidelity, and still others will call for minimalist displays with a rock-bottom price.

"The display technology has been arriving to enable good Internet devices," said Joel Pollack, vice president of the display products business unit of Sharp Electronics of the Americas (Camas, Wash.). "Now the infrastructure has to catch up to enable the performance for wireless operation that users will be demanding. This could be one of the most exciting areas for development in the next two years."

The next few years will also define the economics that will drive display choices. Some IAs may be sold for profit while others for a token payment, with the cost of the device subsidized by service revenues. The latter "subscription" model can cut two ways: the service provider may be attracted to the least expensive alternative to more rapidly recoup its costs; or it may be moved to dig deep into its pockets to pitch premium displays to an upscale user base.

Display market watcher Stanford Resources Inc. (San Jose, Calif.) foresees fast growth for IA displays from a dead start in 1999 to about 25 million units in 2006 with an estimated value of $1.25 billion. "We're forecasting mostly passive LCDs because of price constraints," said Paul Semenza, manager of strategic market analysis at Stanford.

"The big caveat is that if AM LCD prices continue to drop as they have been--and we don't think they will-the price/performance factor will push people in that direction," Semenza said. "But right now, with appliances trying to adopt the subscription model, where the hardware wants to be free, that's pushing people toward passive LCDs."

Barry Young, vice president at DisplaySearch (Austin, Texas) noted there's very little price differential at 8.4-inch sizes and above between passive LCDs and AM LCDs "because of the excess capacity for large TFTs." In such a case, other issues besides price come to the fore, such as the superior imaging performance of AM LCDs or the superior power picture of passive LCDs.

"The incumbent and the best game in town from a power and price point of view today is the passive LCD," said Chuck McLaughlin, principal analyst at The McLaughlin Consulting Group (Menlo Park, Calif.), which is just wrapping up a report on low-power displays. He noted though, that the video and color capabilities of the passives are "nothing to write home about."

"It's easy to discount them and say they're going to get swept out of the market by AM LCDs, OLEDs, etc.," McLaughlin said, "but that's not going to happen because of four major technical innovations being implemented in passives today: reflective color; the replacement of backlights by front lights; active addressing; and a whole new family of passive controllers with embedded DRAM and more sophisticated refresh and power-savings mechanisms." In the cell phone arena, he said, "when you add all that together and can get 100 x 100 pixels with 4,000 colors for roughly 3 mW, you've got a winner. Extensions of that will carry forward into larger form factors."

McLaughlin also pointed to the promise of LTPS (low-temperature polysilicon) AM LCDs, notably a "totally remarkable" 3.7-inch, 1/4-VGA display from Sony, which operates off just 20 mW.

David Mentley, senior vice president at Stanford Resources, predicted that the AM LCD should capture "about a 20 percent share in 2006," and by then, he added, "the OLEDs organic light-emitting diodes will be coming in, too."

Challenging the passive
"The AM LCD is the ideal screen for the application," said Matthijf Hutten, product manager for the net displays group of Philips Components (Sunnyvale, Calif.). This group is fielding an IA component called the Netdisplay module, which integrates a display and a system board to deliver what Hutten said provides 80 percent of the hardware necessary for an IA. The nature of the IA's application mix is then defined when the IA maker adds its special hardware and software.

The first iteration of the module contains a 10.4-inch, SVGA (800 x 600-pixel), backlit AM LCD with 18 bits of color and, of course, a touchscreen for user input. The reason passive LCDs won't cut it, Hutten said, is that IAs will be "not only for Internet browsing but also for streaming video, and for that, you need an active-matrix screen. The refresh rate of passive LCDs is too low to do high-performance streaming video," he said.

On the power front, the Netdisplay module can only support "maybe two hours of battery life for the most demanding applications with video streaming," Hutten said. But it's got quite a longer battery life "for Internet browsing because a lot of the time, you're just refreshing the image and not downloading new pages," he said.

Down the road, said Hutten, transflective AM LCDs may be an appropriate follow-on to backlit AM LCDs, drastically reducing power dissipation. He also added that OLEDs "look very interesting, but they have a huge price differential with LCDs. We're looking at them, but not for the first generation."

"Internet appliances come in lots of flavors," said Sharp's Joel Pollack. "Some look a lot like simplified PCs, some look like high-end phones, others are installed in other appliances like refrigerators, others hang on the wall like a picture and have a specific application for displaying digital photos. Distinctly different are handheld Internet appliances that are something like PDAs or smart phones."

The first batch of IAs, Pollack said, "would ideally be outfitted with SVGA screens of 10-inch or larger formats. But if they look like phones, the consumer seems to expect a price somewhat like a high-end phone. To do this with an AM LCD or even a passive LCD challenges the price points that these displays have reached, even in today's price-declining LCD market. As the expectations for Internet move to multimedia," Pollack concluded, "the performance of passive LCDs will not be adequate."

But "highly mobile Internet devices," Pollack said, are a completely different situation. "The format can be smaller to enable easy portability and, as a portable product, it must have very low power consumption and must be legible in all ambients from the darkened room to the outdoors," he said. "If combined with a PDA and a cell phone, the expectations for price may be somewhere at that of a high-end PDA. As it combines the features of several tools, it is more tolerable to pay more in that it could still represent a savings to the user."

Here, said Pollack, transflective active-matrix LCDs with formats between 1/4 VGA (320 x 240 pixels) and VGA (640 x 480 pixels) in a 3- to 4-inch size are appropriate. Because they have no backlight, these LCDs have "dramatically reduced power to ensure lightweight and thin designs." Further, he added, passive LCDs with plastic substrates are a contender in small sizes, with the advantages of "durability and even lighter weight."

Pollack pointed to Sharp's continuous grain silicon (CGS) AM LCD technology as a future enabler for "high-resolution, small diagonal displays with system-on-panel capability that will enable further compression of system requirements into the display for portable Internet applications. Unlike emissive devices such as OLEDs," he said, "these products will not wash out in bright ambients and will be favorable in power consumption, especially when showing a screen filled with Internet data."

Challenge to LCDs
Would-be OLED makers have ambitious plans to cut into LCD territory, claiming a size, weight and power advantage over liquid-crystal displays, combined with superior imaging. The true power picture of organic light-emitting diodes has yet to be established, but the other advantages are not in dispute. The most frequent reason given for returning merchandise purchased online, according to studies, is that the merchandise "didn't look like" the image of the merchandise on a screen. The OLED crowd says they've got an answer.

"Ordering a book is one thing," said Les Polgar, president and general manager of Kodak Display Products (Walnut Creek, Calif.). "You need a title, author, price, publisher, etc. But for anything with any aesthetic attributes-whether a garment, a piece of furniture or a car-people want to know what it looks like." OLEDs, he claimed, can handle "much richer content" than today's LCDs.

Polgar lauded the utility of contemporary cell phones as "marvelous, trusty devices, but I can't imagine spending much time looking at the LCD display with the image quality, viewing angle, color, contrast and brightness where they are today."

McLaughlin believes, however, that OLEDs represent "a classic case of designing to beat what your competition had two years ago. The power picture is better than it is for backlit LCDs but worse than for transflective LCDs," he said. The OLED power specs being touted represent only a modest improvement over backlit LCDs, he said, "and even to get to that point, they measure with only part of the pixels on. If they ever turn the whole thing on and show video, their numbers are right back up to where the backlit LCDs are."

The bottom line, said McLaughlin, is that both passive and AM LCDs "can handle the entire spectrum of portable display needs, so where is there room for OLEDs? Do they have the potential for gorgeous emissive pictures? Yes. But they are being optimistic if they think they'll get a big share of this market. They're more expensive and they'll probably always be more power than reflective LCDs."

According to Tom Martin, worldwide program director for flat panels at IBM Corp. (Raleigh, N.C.), "OLEDs are very good and they're coming, but they're not here yet. By the time they get through the development phase, AM LCDs will have gotten even cheaper."

And, said Stanford Resources' Mentley, "Despite incredible enthusiasm over OLEDs, established technologies offer a known quantity and have numerous reliable suppliers: there's a lot of inertia because the pipeline is flowing. The OLED must overcome the technical challenges of a young technology with less than ten years of development. There never has been a case of a new technology taking over a large part of the market in a few years."

In the long run, though, the promise for OLEDs is great. The very low profile of the displays "immediately frees up several millimeters of space in a device," said Stewart Hough, vice president of business development at Cambridge Display Technology Ltd. (Cambridge, U.K.). "And that works to the system designer's advantage to either make the overall package smaller or let him pack in more features." Further, he said, "Wide angle, video speed and great color saturation makes the OLED an excellent candidate for 3G-type applications."

Other alternatives
Other alternative display technologies besides OLEDs will compete for the IA space in the future, including emissive candidates, such as the ThinCRT field-emission displays (FEDs) of Candescent Technologies Corp. (San Jose, Calif.); reflective candidates such as the electrophoretic displays being developed by E Ink Corp. (Cambridge, Mass.) and the MEMS (microelectromechanical system) displays being developed by Iridigm (San Francisco); plus a variety of microdisplays.

Candescent, which expects to ship production-level 5.3- and 7-inch displays in 2003, will target videocentric applications, according to Mark McDonald, applications engineering manager. "We believe our value is true CRT color, fast response, wide viewing angle and low power," he said.

There's an opportunity for microdisplay-based gear in the portable IA arena, providing a large magnified, projected or virtualized image in minimal space and requiring minuscule power.

"There are the wrist- or pocket-type devices you'd want to look at with a small amount of magnification, maybe 10 or 20 percent to keep costs down," said Gary Jones, president and CEO at eMagin Corp. (Hopewell Junction, N.Y.), a maker of OLED-on-silicon microdisplays. "The next step up is handhelds where you go to 20 or 30 percent magnification and you can have a whole Web page in your pocket. The next step is head-wearable; and a step beyond that adds 3-D stereo capability and head tracking and you can have 20 or 30 pages hanging in all directions on all sides of you there all the time."

According to Anthony Artigliere, vice president of field operations at LCoS (liquid crystal on silicon) microdisplay maker Displaytech Inc. (Longmont, Colo.), "The use model for portable microdisplay-based products is not clearly defined yet," but he can foresee several such models, including the bring-to-the-eye model and the wearable model.

There's yet another compelling advantage of microdisplays, which it shares to a lesser extent with LTPS and other advanced active-matrix technologies on which LCDs, OLEDs and other displays will be built. That's the ability to incorporate much of a system's circuitry into the substrate of the display itself.