Not all touchscreen phones are created equal

Touchscreen phones are among the hottest phones out now, with the iPhone 3G, the Google Android G1, HTC’s Touch Diamond and the BlackBerry Storm leading the pack.

But after some comparison shopping it becomes clear that not all touchscreens are created equal. Some won’t work if you have gloves on and some are slow to respond.

Other models have a nearly perfect interface between your finger and the phone; menus flow smoothly with a flick and gestures zoom and pan complex Web pages. That’s why it’s definitely wise to try before you buy if you’re considering a touchscreen phone.

Touchscreens perform differently from phone to phone because various technologies — for both hardware and software — are at work.

LG LG's Dare uses a resistive touchscreen.

Resistive touchscreens
The most common type of touchscreen, featured on the LG Dare, Samsung Instinct, HTC Touch Diamond and many other phones, uses “resistive” technology.

Resistive screens are comprised of several layers. The top layer, usually a clear polyester film, is flexible. When a finger presses down, the top layer comes in contact with a lower glass layer. The voltage is measured and the location of the press is computed.

Resistive screens are “the workhorse of touchscreen technologies,” said Andrew Hsu, strategic and technical marketing manager at Synaptics, a company that specializes in touchscreen technologies.

“Resistive touchscreens have, during the last two decades, delivered on the promise of sturdy, reliable and economical touch-based user interaction on a variety of applications,” he said.

Input is possible with fingers, both bare and gloved, as well as with a stylus. In Asia, where a character alphabet is used, a stylus and handwriting recognition are necessary, so resistive screens are hugely popular there.

The downsides to resistive screens include less-than-perfect transparency, scratch-prone surfaces and components that wear out and break over time.

In most Western countries, resistive technology is falling out of favor with touchscreen fans.

Capacitive touchscreens
Apple’s iPhone, the G1 and BlackBerry Storm all use the more sophisticated “capacitive” technology.

Capacitive touchscreens work well with crystal-clear glass as the touch surface. A circuit board sensor beneath the glass registers changes in electrical capacitance, or charge, when activated by a finger’s electrical charge.

The Android-powered G1 and BlackBerry Storm both use Synaptics’ ClearPad capacitive technology.

“No pressure is necessary to activate the capacitive sensor,” said Hsu. “A gentle stroke or glide along the surface of a capacitive pad is all that is required. There are no moving parts to wear out over time, and with a rated life of over 1 million uses, Synaptics ClearPad and TouchPad will probably outlast your device.”

The differences between using a phone with capacitive and resistive screens can be striking: the iPhone’s bright, bold display makes the LG Dare or Samsung Instinct seem dim in comparison.

Apple’s slick multi-touch gestures, such as pinching and spreading two fingers to zoom and reduce on-screen objects, are only possible on a capacitive screen.

Limiting capacitive touchscreen appeal, especially in Asia, is the need for a special capacitive stylus. Also, a bare finger is required for operation since the body’s electricity is blocked by gloves.

In a recent report, ABI Research noted that Asia’s need for screens “that support handwriting recognition input with a stylus” is the main reason why capacitive touchscreen phones will “not be the wave of the future for most mobile phones.”

And any phone with a glass screen, including the iPhone and BlackBerry Storm, requires extra care. Web discussion forums are jammed with customers' tales of iPhone screens shattered after being dropped.

Hardware technology is only part of what makes touchscreen phones work. The software, from the operating system to the user interface, is every bit as critical for usability.

“Touch-based technology is becoming an increasingly visible and integral component, but touch innovation is no longer about just adding a touchscreen to a device,” said Peter Recchi, HTC’s director of product management.

“Today, true touch is about the deep integration of touchscreens with intuitive touch interfaces. This is what makes touch special and natural.”

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