Immersion is working on an innovation that could help. The company is collaborating with partners to develop "deformable surfaces" that would allow certain areas of the touch screen to rise up, creating key positions you can feel.
"When electric fields are applied to them, they deform -- raise up or sink down. Those surfaces would be on top of the touch-screen display," says Sheehan, so this could help users position their fingers by feel. But don't expect products anytime soon: Sheehan describes the work as part of the company's "long-range vision."
Make that very long-range vision, says Levin. Pacinian has researched different deformable materials, including one called electroactive polymers. Most of the work in developing deformable surfaces, Levin says, is still in university research labs, although several companies, including Microsoft, Apple and Nokia, have filed for patents in this area.
"We have put that aside for the near term, as they still have problems with robustness and reliability, especially across varying temperatures and humidity. It's unclear which of the early concepts will actually work, much less [be] able to be manufactured reliably and cost effectively," Levin says.
Then there's the sticky issue of key travel. On a touch screen, your fingers are pressing on a hard glass or plastic surface. Haptics can simulate key travel to an extent, but the technology today is very limited.
Pacinian's "force sensing" electrostatic surface actuation technology comes into play here as well. The sensor can tell which keys you're pressing and how hard, and apply feedback that may help create a sensation of movement, Levin says.
But Pacinian's technology won't work for an entire virtual keyboard on a touch screen because the pressing sensation as engineered today isn't granular: It gets applied to the entire touch surface rather than to a specific area of it. It can tell the position on which your fingers are pressing, but it can only do force sensing for one position -- one finger -- at a time.
This limitation derives from the fact that most touch-screen displays today use a single sheet of glass as the top layer. Pacinian is researching designs that use a plastic top layer, which allows for multifinger pressure sensitivity. "A flexible surface can have regional sensing and actuation," Levin says. But there's a trade-off: Plastic is less transmissive than glass, so the screen may not be as bright.
Getting to 'good enough'
The virtual keyboard experience, which is not great today, will get much better, the experts say. But will it ever be good enough to replace a traditional keyboard for intensive data entry on a desktop or laptop?
Jennifer Colegrove, an analyst with display market research firm DisplaySearch, thinks it will. "But both hardware and software need to improve to reach that point, and price reductions are needed for adoption," she says. For now, she adds, touch and mechanical keyboards will coexist for use with laptops and other computers.
As for when virutal keyboards might replace mechanical ones, that's likely still years away. "Some notebooks and all-in-one PCs that only use touch-screen keyboards have already been demonstrated, or patents have been applied for them. I expect those to enter the market within 12 months, but high volume is still five or more years away," says Colegrove. She predicts that virtual keyboards will be good enough for touch typists in 10 years.
Other experts aren't so sure that a virtual keyboard can ever replace a good mechanical one -- particularly for touch typists. Ken Bosley, software product manager for Hewlett-Packard's Consumer Desktop Global Business Unit, says HP hasn't seriously considered including haptics in the company's TouchSmart line of capacitive touch-screen PCs.
Both laptops and desktops in the TouchSmart line offer virtual keyboards, and the display on the desktop version tilts to 30 degrees for easier typing. But typing on it is still awkward, and Bosley doesn't think most people use the virtual keyboard since a physical one is readily at hand. He says it's there only because users have come to expect it on touch screens.
He doubts screen-based virtual keyboards will ever replace electromechanical models for desktop PCs and laptops. "The reason I don't like virtual keyboards is that I can't touch type on them," he says.
Andrew Hsu, technology strategist at touch-screen maker Synaptics Inc., also doesn't see virtual keyboards dislodging their physical cousins. "Some of the most difficult problems for haptics are simulations of mechanical devices," he says, and there will continue to be a need for electromechanical keyboards for the foreseeable future.
But, Hsu adds, to try to replicate the experience of a mechanical keyboard on a touch-screen surface is to miss the point. "We could enable more realistic keyboard input if that's what we continue to require five years from now," he says, but why would touch-screen makers want to replicate the usage scenarios and paradigms from the mechanical keyboard era?
Hsu points to gesture-based applications such as Swype, which lets users "type" by sliding a finger across a virtual keyboard. "With a lot of gesture-based interactions, having a mechanical input device like a keyboard becomes almost unnecessary. You can already see a lot of kids adopting it very easily," Hsu says.