Microsoft's Many Multitouch Mice

Last week Apple released the Magic Mouse, a new computer mouse with a "multitouch" interface that responds to movement of fingertips across its surface in addition to conventional click-and-drag actions. Archrival Microsoft isn't ready to launch a competing product just yet, but the company does have plans for its own multitouch mice. Earlier this month, researchers presented five prototypes at the User Interface Software and Technology in Victoria, British Columbia, and their work won the symposium's best paper award.

With a multitouch mouse, a user can, for example, browse through a virtual stack of digital photos by flicking a finger across the mouse's surface, rotate an image by stroking the mouse, or zoom in on a picture by drawing an arrowhead with a fingertip.

"If the [traditional] mouse pointer is your virtual fingertip, we're giving you a virtual hand," says Dan Rosenfeld, a researcher with Microsoft's Applied Sciences Group in Redmond, WA. There are multitouch surfaces for tabletops, computer monitors, and cellphone screens, he says, but aside from Apple's new device, "there's really nothing addressing the kind of tasks that lots of people do all day long, sitting in front of a desk at a computer."

The first mouse outlined in the Microsoft research paper consists of a piece of clear acrylic lit with infrared light along its edge, where it attaches to a palm rest. Fingertips on the acrylic scatter the light, and an infrared camera captures the light patterns to track the movement of the fingers. The technique, known as frustrated total internal reflection (FTIR), has been used for other multitouch systems before, but this is the first design that also integrates the classic features of a mouse such as an optical sensor underneath and clickable buttons.

Another prototype, the dome-shaped Orb Mouse, also uses an infrared camera and light, but it reflects the light out of its center to make its entire hemisphere touch-sensitive. The dome also acts as a giant click button.

SideMouse, in contrast, positions the palm of the user's hand on top and projects infrared light out of its side to track the user's fingers as they move along the table next to the mouse.

The Cap Mouse abandons the infrared scheme altogether, instead tracking finger movements with a grid of capacitive sensors on its surface. Unlike the mice that rely on infrared technology, Cap Mouse isn't affected by ambient lighting, consumes less power, and offers a less detailed account of finger movements.