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Size Matters

When it comes to portable devices, people’s expectations outstrip what they demand from a desktop. “Users using a mobile device are much more sensitive to the time it takes to perform a task than they are when they are sitting at their desk,” says Mike Flom, CEO of Portable Internet in Park Ridge, NJ. Yet the screens and displays of mobile devices remain thoroughly inferior to those of PCs. “I don’t care how many bits per second you’ve got, if I’ve got a [five-centimeter by eight-centimeter] display, there’s only so much I can do with that,” says Eric Schaffer, founder and CEO of Human Factors International, a Fairfield, IA-based software usability consulting firm.

Not only are the screens small, but their resolution remains stubbornly low-only a fraction of that available even on the cheapest computer monitors. As a result, each letter or image needs more screen space to be legible. That limitation plus a miniscule screen adds up to one big frustration.

One solution: larger screens. The extra space might come from a flexible screen that unfolds like a map. Plug it into a pocket computer and you have as much visual real estate as you’d find on a desktop, or at the very least on your cumbersome laptop. Indeed, that development could spell the end of the laptop. “If I had a palm-sized device thatI could fold out to be a full-sized display with a competent processorand one of those fold-up keyboards,” asks Flom, “do I need a laptop anymore?”

Pocket-sized, foldable screens are only a few years away. Both E Ink of Cambridge, MA, and Gyricon Media, a Xerox spinoff in Palo Alto, CA, have been developing thin displays with “electronic ink” technology (see “Electronic Paper Turns the Page,” TR March 2001). Electrostatic charges orient white microscopic particles suspended in tiny spheres. An underlying circuit controls the charge and whether or not the spheres show as white or dark. The companies are also looking into eventually developing flexible color displays.

Although electronic ink is on the technology horizon, it isn’t quite ready for mobile electronics use. The prototypes being developed by E Ink and Gyricon Media provide reflective displays, relying on the environment for illumination. That may be fine outdoors or in a bright room, but not in dim surroundings.

But electronic ink is not the only little big screen solution in the pipeline. Another approach keeps the display small-two centimeters or less in diagonal-but offers good resolution and an effective screen size many times its physical dimension. The solution makes use of magnifying lenses mounted in monocular units or goggles. The magnifiers pump up visuals to the scale seen in conventional full-sized monitors. InViso of Sunnyvale, CA, for example, makes a handheld device that, in conjunction with glasses, offers images 800 pixels across and 600 pixels high-the same resolution as a standard 35.5-centimeter desktop monitor. Large companies are also entering the market, with Sony’s Glasstron and the Eye-Trek from Olympus both giving the viewer an image equivalent to a 132-centimeter screen seen from about two meters away.

Of course, this approach raises the question: why not just cram more pixels into tinier screens for better resolution? The answer has to do with the physics underlying the most common technology used in handheld screens-liquid crystal displays. These displays are a multilayered sandwich of components backlit by a light source. The light must pass through electrode strips to illuminate the pixels on the surface of the screen. Whether a pixel gets illuminated is controlled by a thin-film transistor connected to the electrode strip. A current flowing from the transistor makes the strip opaque; no current lets light through. But as the pixels shrink, they soon become smaller than the transistors, which then block out the light, whether they’re on or off.

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Tagged: Communications

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