Microsoft is suing Barnes & Noble over its Nook e-reader, saying the reader's Android operating system infringes on Microsoft patents.
Without actually suing Google itself, Microsoft contends that in developing Android, Google has infringed on Microsoft's patents. Microsoft has also sued Motorola over devices that use Android.
"Together with the patents already asserted in the course of our litigation against Motorola, today?s actions bring to 25 the total number of Microsoft patents in litigation for infringement by Android smartphones, tablets and other devices," Horacio Gutierrez, deputy general counsel, wrote in a Microsoft blog post today.
The lawsuit also names the Nook's manufacturers, Foxconn, International Holdings and Inventec.
Gutierrez said Android features on the Nook violate Microsoft patents that create a tabbed control window, display Web pages while images are downloaded in the background and a way to allow readers to select text on the device.
Microsoft said Amazon.com pays a license fee for its Kindle e-reader.
Update 2:47 p.m.:
Barnes & Noble declined to comment on the lawsuit.
Microsoft filed the case in U.S. District Court in the Western District of Washington state.