Microsoft was sued on Thursday by Vringo Subsidiary I/P Engine. The company alleges Microsoft has been infringing patents that allow Internet search engines to most effectively place advertisements.

The patent infringement lawsuit was filed in the Southern District of New York. The lawsuit alleges infringement of U.S. Patent Nos. 6,314,420 and 6,775,664, entitled "Collaborative/Adaptive Search Engine" and "Information Filter System and Method for Integrated Content-Based and Collaborative/Adaptive Feedback Queries," respectively.

Microsoft uses the technology in systems that generate advertisements and associated links for users of the world's largest software company's search engine, Bing, the lawsuit said.

According to the complaint, I/P Engine is seeking a judgment declaring that Microsoft has and continues to infringe the patents-in-suit, and an award past and future compensatory damages amounting to no less than reasonable royalties, prejudgment interest and any other damages based on any form of recoverable economic injury.

Last November, I/P Engine had been awarded approximately $30 million in damages after it found that Google and AOL had infringed the same patents that are at issue in the Microsoft suit.

Vringo, Inc. is engaged in the development and monetization of mobile technologies and intellectual property. The company's intellectual property portfolio consists of over 500 patents and patent applications covering telecom infrastructure, internet search, and mobile technologies. The patents and patent applications have been developed internally, and acquired from third parties.