Immersion said yesterday that it plans to license its force-feedback technology to handset makers, which will make virtual buttons on mobile phone screens.

Fans of Sony's PlayStation 2 or Microsoft's XBox are already familiar with the tactile reactions they feel in joysticks and steering wheels on their gaming consoles. Now the technology could move to mobile devices.

Built into a PDA or smartphone, a haptic screen doesn't actually flex against a user's finger; instead, a small electric motor behind it delivers a small tap. Combined with an audible 'click' feature, the overall effect helps mimic a mechanical button on a digital screen.

Immersion plans to license the technology to manufacturers of smartphones and PDAs who want to improve the utility of their touchscreens, said Mark Belinsky, vice-president of market strategy at the California company.

The technology is similar to Immersion's VibeTonz System, which mobile phone vendors already use to synchronise ring tones and video games with tactile vibrations.

Samsung uses VibeTonz in its SCH-A930 mobile phone, allowing users to identify callers without taking a muted phone out of their pockets, since the phone vibrates differently for each assigned ringtone, Belinsky said.

Samsung also uses haptic technology to add a sensory dimension to video games. Game makers including Punch Entertainment, SkyZone and Sonic Branding Solutions have signed agreements with Immersion to use VibeTonz technology.

Vibrating songs and games are decent gimmicks for selling phones to kids, but the real payoff will come when vendors use haptic technology in their touchscreens, said Avi Greengart, principal analyst for mobile devices with Current Analysis.

"If you're just trying to make a phone that's more exciting for young people, maybe that's exciting or maybe not," he said. "But when it comes to giving force feedback to a handset, this gives you the physical sensation that you just pushed a button, and that's compelling."

As handsets get thinner and begin to host richer media, their designs feature "all screen and no buttons", Greengart said. The challenge for vendors is how to let users know which button to press, and which button they have just pressed? Tactile feedback is the best answer yet, he said.

Immersion has licensed similar technology for years to manufacturers of video game consoles, medical training simulators and automotive dashboard manufacturers. The company is locked in a trademark infringement lawsuit with Sony, which allegedly uses Immersion's technology in the PlayStation series.