Bloomberg has reported that Konami has filed a lawsuit against MTV/Viacom-owned Rock Band developer Harmonix, claiming that the company violated several of Konami's patents from 2002 and 2003 related to simulated musical instruments, a music-game system and a "musical-rhythm matching game."

Konami, of course, has been a pioneer in the music/rhythm genre in its own right, having launched franchises such as Guitar Freaks, DanceDanceRevolution, Karaoke Revolution and others. Konami also hopes to compete more directly with the likes of Rock Band and Guitar Hero when it launches Rock Revolution later this year.

As for the suit, Konami is demanding cash compensation, plus an order that would block Viacom and Harmonix from using the inventions, said Bloomberg. Viacom told the publication it had not yet received the complaint (filed on July 9 in federal court in Marshall, Texas) and would not comment.

Update: A Harmonix spokesperson told Wired, "Konami's actions are extremely surprising. Unfortunately, successful products such as Rock Band can often become targets for baseless litigation. We have substantial defenses to this claim and intend to vigorously defend it."