The Nook Color, a target of Microsoft&39's lawsuit.

Microsoft filed suit today against Barnes & Noble as well as the makers of its Android-based e-reader and tablet devices for patent infringement, part of its broader campaign against Google's mobile operating system.

The software giant alleges that its patents cover a range of functions "essential to the user experience." The company specifically cites the way users tab through various screens on the Nook e-reader and the Nook Color tablet, both of which run Android, to find the information they're after, as well as the way they interact with documents and e-books.

"The Android platform infringes a number of Microsoft's patents, and companies manufacturing and shipping Android devices must respect our intellectual property rights," says Horacio Gutierrez, Microsoft's corporate VP and deputy general counsel for intellectual property and licensing, in a press release.

Microsoft says it's tried to no avail to reach licensing agreements with Barnes & Noble and its hardware partners. "Their refusals to take licenses leave us no choice but to bring legal action to defend our innovations and fulfill our responsibility to our customers, partners, and shareholders to safeguard the billions of dollars we invest each year to bring great software products and services to market," Gutierrez says.

The suit was filed with the International Trade Commission and the U.S. District Court of the Western District of Washington. Microsoft also named Foxconn International Holdings and Inventec Corporation as defendants in the case.

Horacio Gutierrez, Microsoft's deputy general counsel for intellectual property and licensing

A Barnes & Noble spokeswomen declined to comment on the suit, saying the company doesn't comment on litigation as a matter of policy. Google, though, fired back. "Sweeping software patent claims like Microsoft's threaten innovation. While we are not a party to this lawsuit, we stand behind the Android platform and the partners who have helped us to develop it," Google spokesman Aaron Zamost said.

Microsoft previously sued Motorola, alleging that several of its Android devices infringe on Microsoft patents. Microsoft would prefer that companies making Android devices follow the lead of its longtime partner HTC, which worked out a deal last year covering its own Android devices.

Despite its many patents, Microsoft rarely sues over infringements. In a blog post, Gutierrez says that this suit is the seventh proactive patent infringement case brought by Microsoft in its 36-year history. "We simply cannot ignore infringement of this scope and scale," Gutierrez writes.

Microsoft, which is losing ground to Android in the marketplace, is pushing hard to take the fight to the courthouse. One tactic: make using Android, which is offered for free to manufacturers, more costly by raising the specter of litigation. Microsoft has claimed over the years that Linux-based products infringe on its patents, which has led to several licensing deals with companies making devices using the technology. And Android is based on the open-source operating system.

As Todd Bishop of GeekWire notes, the patents Microsoft is alleging infringement of are different from the ones cited in the Motorola case. This time, Microsoft is suing over patents such as ones that cover editing electronic documents, and capturing and rendering annotations.

The market for mobile devices is so lucrative that litigation is a key strategy to keep rivals off balance. Last year, Apple sued HTC for infringing on iPhone patents covering the graphical user interface and the underlying design. And Oracle, too, sued Google, alleging it infringed on patents related to Java in Android.

A once loyal partner The size of the market is clearly one reason why Microsoft is willing to take on Barnes & Noble, long a loyal partner and customer for a variety of products and services. A decade ago, Barnes & Noble was one of Microsoft's marquee partners for its Microsoft Reader software, an early entrant into the electronic book market. Back then, Barnes & Noble created an eBook superstore, using the Microsoft technology, for customers who wanted to read books on laptops and the existing hodgepodge of dedicated reading devices that used Microsoft's technology. That business has since shuttered.

Barnes & Noble also partnered with Microsoft on its ill-fated Windows Live Search Cashback program, which paid rebates to customers who found products with Microsoft search engine and purchased them. And Barnes & Noble lent its name to the list of customers touting its business intelligence software back in 2004.

In addition to a permanent injunction barring the defendants from infringing on Microsoft's patents, the company is also seeking compensatory damages "with interest and costs, and in no event less than a reasonable royalty" as well as treble damages for the defendants "willful and deliberate" patent infringements.