After three years, Gibson, one of the exclusive partners of Activision's Guitar Hero franchise, claims the game infringes on one of its patents and has notified Activision. In 1999, Gibson filed a patent for technology simulating a live performance using a musical instrument, a 3D headset with stereo speakers, and a pre-recorded concert. Not wanting to sit by idly, Activision has filed a lawsuit asking the U.S. District Court for California to declare Gibson's patent invalid and to bar it from seeking damages.