Apple Inc.'s iPhone is leading a new wave of gadgets using touch-sensitive screens that react to taps, swishes or flicks of a finger. The improvements promise to be slicker and more intuitive than the rough stomp of finger presses and stylus-pointing required by many of today's devices.
Apple has already been showing off its finger ballet in video ads before the smart phone's launch June 29.
Glide a finger across the screen to activate the device and main menu. Slide your digit up or down to scroll through contacts. Flick to flip through photos. Tap to zoom in on a Web site.
With Apple's marketing machinery, the iPhone is poised to become the poster child for the new breed of touch-screen technology, which relies on changes in electrical currents instead of pressure points.
But the iPhone will have rivals.
Shipments of this advanced strain of touch screens are projected to jump from fewer than 200,000 units in 2006 to more than 21 million units by 2012, with the bulk of the components going to mobile phones, according to a forecast by iSuppli Corp., a market research company.
"This new user interface will be like a tsunami, hitting an entire spectrum of devices," predicted Francis Lee, the chief executive of Synaptics Inc., a maker of touch sensors.
Synaptics' latest technology is in a growing number of cell phones, including LG Electronics Co.'s LG Prada touch-screen phone that launched this year in Europe and South Korea and handles gesture-recognition like the iPhone.
Apple does not comment about its component suppliers, and Mr. Lee declined to comment on whether Synaptics is working with Apple on the iPhone.
Last fall, Nokia Corp.'s research and development unit unveiled online images of a prototype all-touch-screen cell phone called the Aeon, but the company hasn't disclosed any details of its features or market availability.
"Touch screens are going to be more common, period, because rivals will slap them on to compete with Apple," said Michael Gartenberg, an analyst at JupiterResearch.
Even before the iPhone hype kicked into high gear over the past few months, touch screens in general were becoming more popular in cell phones. About 38 million handsets, or about 4 percent of all mobile phones shipped in 2006, had touch-screen features - a figure that will grow to 90 million units by 2012, iSuppli projected.
But most touch-screen phones that shipped last year, including Palm Inc.'s Treo and Motorola Inc.'s ROKR E6, used "resistive touch" technology - the most common technology, said Jennifer Colegrove, a senior analyst of display technologies at iSuppli. It has two layers of glass or plastic and calculates the location of touch when pressure is applied with either a stylus or a finger.
A more advanced type of touch screen, featured on the iPhone and LG Prada, uses "projected capacitive" technology. A mesh of metal wires between two layers of glass registers a touch when the electrical field is broken.
That's why light finger brushes will do the trick. But capacitive sensors don't even need actual physical contact: such touch screens already detect the proximity of a finger from 2 millimeters away, Ms. Colegrove said.
The iPhone is the only cell phone that can handle more than one finger at once, analysts say. That technology, which Apple has patented, allows users to resize a window, for instance, by pinching or expanding two fingers on the display.
"Multitouch" technology is not new but has only recently begun to emerge beyond research labs and product prototypes.