Machine Design

Fastest mouse on the desk

Spreadsheets and word-processing documents are getting larger, some with embedded images and music files, and average PC users keep six applications open on their computers at any one time and switch between them every 50 sec.

They also spin their mouse's scroll wheel about 26 ft every day. To make sure no one's fingers wear out, researchers at Logitech Inc., Fremont, Calif. (, have redesigned the scroll wheel in their MX Revolution mouse.

It used to have a 2.4-gm plastic wheel, but the low-mass wheel didn't spin freely for very long. The new 14-gm metal wheel is wrapped in a rubber grip band and mounted on ultralow-friction bearings. (Tests show a single flick can send the scroll wheel through 9,000 rows in a spreadsheet.) The wheel mount, in turn, sits in an automotive-style suspension that lets the wheel move side to side for sideways scrolling, and still have enough vertical travel for the wheel's pushto-click function. The suspension also counterbalances the wheel's mass, stiffens the housing, and reduces wheel noise.

The mouse detects the currently active application and applies the most appropriate scrolling method. For word processing, for example, a small lowpower motors retract the wheel's ratcheting mechanism to let it free scroll. For browsing through photos, however, the click-toclick mode retains the ratcheting mechanism to let the wheel move precisely line by line. And on some applications, such as spreadsheets, it chooses based on wheel spin. Spin the wheel fast and it goes into free-spin mode; spin it slowly and the wheel goes to click-to-click mode. Users can specify which mode the computer starts up in.

The mouse works with Windows XP or Vista PCs and Macs with OSX 10.2.8 or higher.

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