A New Spin on the Computer Mouse

How Logitech engineered a high-speed scroll wheel that lets users whiz through long documents with the flick of a finger

7 min read

Erico Guizzo is IEEE Spectrum's Digital Innovation Director.

How many engineers does it take to design a computer mouse?

At Logitech, the leader in the global mouse market, it took more than 30 electrical, mechanical, computer, and industrial engineers working for two years to create the company’s MX Revolution, which hit stores on 24 August. The company calls the engineering project the largest in its history.

The new mouse, priced at US $99, has a curvy gray-and-black body and is cordless, optical, and decked with plenty of buttons, but the same can be said of other high-end mice. What sets it apart is its high-speed ”inertial” scroll wheel.

While most mice have a plastic or rubber scroll wheel that weighs a gram or two, the MX Revolution has a 14-gram chrome-plated brass wheel. Turn it slowly and you’ll scroll one line at a time, the wheel’s internal ratchets clicking under your fingertip, just like in a conventional mouse. But give the wheel a good spin and the result is entirely different: a tiny electric motor retracts the ratchet mechanism and the wheel revolves freely for up to seven seconds. A single flick of your finger sends you whizzing through 50 pages in a Word document.

You can also set the mouse to switch between the ”clicky” and smooth modes according to the program you’re using. In Internet Explorer, say, the wheel rolls freely. Switch to PowerPoint and the ratchets reengage, giving you back the more precise scrolling, so you can move through one slide at a time.

”The new inertial wheel—I really think they’re on to something,” says Andy Cockburn, a human-computer interaction expert at the University of Canterbury, in Christchurch, New Zealand, who has tried the new mouse. ”It’s a tiny incremental development, but to me it’s absolutely delightful. If I had thought about it, I’d be pretty happy with myself.”

Logitech, whose revenue reached $1.8 billion in fiscal 2006, says that the new scrolling capability is more than just a cute trick. The ”Revolution” in the name may be pure PR gimmick, but the company showed it’s possible to innovate in a category that hasn’t changed much since Douglas Engelbart and his colleagues invented the mouse in the late 1960s. ”Improving scrolling was high on users’ wish lists,” says Erik Charlton, a senior marketing manager at Logitech and one of the executives behind the MX Revolution. In a recent study the company showed that a user’s mouse-wheeling can add up to 8 meters in a single workday. It would be even more if users didn’t rely on the page-up and page-down keys or the scroll bar when navigating through long text documents, spreadsheets, and Web pages.

Building a Better Mouse

To develop the MX Revolution, Swiss-based Logitech International launched a global effort involving teams in five countries. The marketing people worked at Logitech’s U.S. headquarters in Fremont, Calif., the mechanical engineers in Ireland, the electrical engineers in Switzerland, the tool-and-die makers in Taiwan, and the manufacturers in China.

With two years to go from concept to commercialization and no room for delays, Logitech realized that it need to revamp its traditional way of cranking out new designs. Because the MX Revolution would need many more components than any other mouse and because the engineering teams were scattered in so many places, the project required ”a systems engineering type of approach,” Charlton says.

Systems engineering is normally used to manage hugely complex projects like the development of a jetliner. It is a methodology that basically ties together all parts of a project, making sure that design changes are properly propagated through all subsystems and that problems in one subsystem don’t bring down the whole project.

So rather than marching through design to engineering to manufacturing, Logitech managed all three jobs at once, a parallel process that required everyone to work together intensely to discuss their progress and resolve difficulties.

For the aesthetic and ergonomics work, Logitech turned to an old collaborator, Design Partners, in Bray, Ireland, just south of Dublin. The assignment: create more than just another next-generation model. ”We wanted to electrify the user experience,” says Peter Sheehan, a director at Design Partners.

Sheehan and his team sought inspiration from myriad sources, including comprehensive ergonomics data and studies on consumers’ emotional responses to certain products. After much brainstorming, the work became more hands-on, with the designers carving models out of light foam and fiberboard. ”We made literally buckets of them,” Sheehan says. ”They are little pieces of sculpture which can tell you a whole lot.”

Logitech and Design Partners then settled on the mouse’s look and feel and also on its capabilities. At this stage, they had a vision, not a blueprint. They wanted ”silk-smooth precision scrolling,” but they didn’t yet know how to achieve it.

To turn the vision into something literally palpable, Logitech called on Denis O’Keeffe, a senior mechanical engineering manager based at the company’s design center outside Cork City, Ireland. He led the team responsible for the mouse’s key parts—its outer shell and inner mechanisms.

An affable, detail-oriented guy, O’Keeffe had reacted to many previous designs by saying, ”You know we can’t make this!” This time wasn’t different. The idea of a scrolling mechanism that could spin smoothly and at the same time maintain its precision seemed particularly challenging.

The engineers held countless brainstorming sessions, trying to come up with new ways of scrolling. They created numerous prototypes using everything from gearboxes to flywheels. One engineer even harvested his son’s toy motorbike and embedded its motorized wheel into a mouse. (It didn’t work so well.)

Finally they hit on the idea of a metal wheel heavy enough to spin like a flywheel yet sensitive enough to scroll line by line. O’Keeffe tried the thing for a few days and then went back to his old mouse, only to realize that their inertial creation was ”fantastic.” ”It really solves the problem of scrolling through long documents,” he says.

To make the mouse engage and disengage the ratchets, the group concluded that the most efficient system in terms of energy requirements, size, and performance was an electric motor. The first prototype worked fine, but it ”was about the size of a desk,” Charlton says. It was clear it wouldn’t be easy to cram sensors, battery, circuit boards, wheel, ratchet mechanism and motor into a mere mouse. O’Keeffe’s team eventually managed to miniaturize the design. Their solution consists of a dc motor the size of an almond. Its axis rotates a cam 275 degrees, pushing a tiny shaft that in turn pushes a little steel ball against the ratcheted wheel hub. Switching from one mode to another takes just 35 milliseconds. In the free-spinning mode, the wheel often reaches 2000 revolutions per minute. ”Some of our engineers got it up to 3500 rpm,” O’Keeffe says.

In addition to the free-wheeling, Logitech added a bunch of other functions to the MX Revolution. To launch a Google search, just highlight some text and push a small rectangular button on top of the mouse. To switch between applications, use your thumb to roll a second scroll wheel Logitech embedded on the left side of the mouse.

The new mouse is ”a pretty compact design,” says Richard L. Owens, a mouse enthusiast from Provo, Utah, who maintains a Web page on mouse technology. He dismantled his MX Revolution to inspect its guts as soon as he got hold of one. ”It’s got quite a few different buttons in different places. Interesting that they can design it at all to fit this stuff.”

In fact, O’Keeffe says, ”the biggest challenge was just the scale of integrating everything together,” adding that ”the size of your hand is fixed, and every year we are packing more and more functionality, pushing the boundaries another little bit.”

If you count all mechanical and electronic components, the mouse has more than 400 parts, and integrating them all required great care. Again, Logitech drew on the systems engineering discipline, borrowing a technique called failure modes and effects analysis, or FMEA, used to assess a project’s riskier parts.

The point was to focus on the most critical subsystems and find out what would happen to the project if unexpected problems in those systems cropped up. The company then turned to CAD drawings, computer simulations, and three-dimensional models created in rapid-prototyping machines to make sure those critical subsystems would work just as expected.

The completed mouse still had to pass a series of tests. ”Our lab is almost like an interrogation center for mice,” O’Keeffe says. His team dropped units onto a steel plate, submitted the devices to extremes of -40 to +70 °C, and even zapped them with electrostatic discharges.

With the design approved by the marketing, mechanical engineering, electrical engineering, and manufacturing teams, the MX Revolution rolled into production, at a rate of one new unit every ten seconds.

Beating a Path to Their Door?

Most people may take their mice for granted, but for users like gamers and artists these devices are more than just boxes with buttons. Some know by heart their mice’s coefficient of friction and maximum acceleration, while others enjoy ”mouse modding”—modifying mice to change their appearance or enhance their tracking and scrolling performance.

Logitech, which has manufactured more than 700 million mice, has long been catering to that crowd. The MX Revolution confirms the company’s strategy of designing products aimed at ”power” mouse users as one way of staying ahead of Microsoft, which is No. 2 in the world mouse market.

”From a business standpoint, it represents Logitech continuing to push up the premium price that it can charge for its products,” says Ross Rubin, director of industry analysis with market consultancy The NPD Group, in Port Washington, N.Y.

But are there people willing to pay $99 for a mouse? ”Certainly,” he says, adding that though the MX Revolution probably won’t be one of Logitech’s top sellers, as a high-end product it can still generate a lot of revenue.

Logitech has also created a cheaper version aimed at notebook users, who are often on the road. The VX Revolution, priced at $80, has the same inertial wheel but users have to engage or disengage the ratchets manually by using a switch on the bottom of the mouse.

There isn’t much question that the MX and VX Revolution will sell, but whether they can substantially improve scrolling and save users a good deal of time during their daily activities is an open question.

Cockburn, of the University of Canterbury, says that with users relying so heavily on the scroll wheel, ”any improvement in scrolling has a big payoff.” He says that since he got the MX Revolution he hasn’t used the scroll bar once while working in Word.

But Cockburn found some glitches, as well. He says that when using the wheel in Adobe Reader to visualize PDF files ”it just basically doesn’t work.” He says that when spinning the wheel rapidly, the pages of the PDF file don’t scroll accordingly.

Ted Selker, a professor at MIT’s Media Lab and an expert in user interfaces, says that inertia ”might feel good, but you have to figure out why you’re putting it in there.”

”When you can’t stop things on a dime, that isn’t control—that’s the opposite of control,” he says. Selker hasn’t done experiments to test the new mouse but he might in the future. That’s the only way, he says, to tell whether the mouse can boost performance and for whom it will make the most difference.

He adds, however, that he likes the idea of the high-speed scroll wheel as ”something to play with.” ”Playfulness is good,” he says. In fact, he hopes that Logitech will give users full control of the mouse’s motorized ratchet system, so they can tinker with it. ”I’d love to have a computer mouse that would give me massages.”

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