Konami has decided to sue Viacom’s Harmonix studio claiming that their hit game, Rock Band, violates patents issued in 2002 and 2003 relating to simulated musical instruments, a music-game system and a "musical-rhythm matching game".

It is demanding cash compensation, plus an order that would block both Viacom and Harmonix from using the inventions. This is interesting as Konami has decided not to sue Activision’s Guitar Hero, which basically is the same as Rock Band, but only with a guitar.

Joystiq is also reporting that Konami created a game titled GuitarFreaks, which is basically the same game as Guitar Hero, for Japanese arcades years ago. It is also going to release a similar game that compares with Guitar Hero and Rock Band called Rock Revolution.