Mobile Computing

Researchers Add Mouse Movement to Phones and MP3 Players

• By Dian Schaffhauser
• 05/03/10

Researchers at Carnegie Mellon University have figured out how to use the same kind of inexpensive optical sensors found in a computer mouse to turn mobile phones and MP3 players into input devices. Nicknamed the "Minput," the technology acts like a mouse or scroll/click wheel, allowing a user to jiggle, twist, or flick the device or scroll it on a surface to activate operations, such as zooming in on an image, turning up volume, or highlighting specific text shown on a screen.

The Minput was developed by Ph.D. student Chris Harrison and professor Scott Hudson through research at the university's Human-Computer Interaction Institute.

"Minput turns out to be a fairly intuitive way to navigate through menus or photo galleries on a device's display without fumbling with tiny buttons or obscuring a small touchscreen with your fingers," said Harrison. "Because we use a pair of sensors, it can respond to a wide range of gestural commands, much like an iPhone or other multi-touch device."

For a prototype, the two researchers mounted two optical sensors on the back of a wristwatch-sized television with a 1.5-inch-diagonal display. Computer processing is performed off-board by a laptop computer. But Harrison said the Minput sensors and processors could be miniaturized to fit inside small mobile devices.

In beta tests, twisting a Minput-equipped prototype device one way or the other allowed the user to perform zooms, and flicking the device against a surface allowed switching between photos or between photo galleries. But Minput also permits high-precision positioning, which is difficult to perform on a small touchscreen, where characters are often far smaller than fingertips.

Should device makers find the Minput a useful addition to their designs, they won't have to invest in creating new sensor technology, Harrison said. "The hard part was done for us; optical sensors are already fantastically well engineered. And at about a dollar apiece, they wouldn't add much to the cost of a mobile phone or music player," he noted. "We just use these sensors in a new and clever way."

Harrison presented a paper on his invention a conference on human factors in computing systems and has posted a video demonstrating the Minput on his Web site.

The work was supported by grants from the National Science Foundation.