According to the suit, as reported by Reuters, Gibson alleges that the series infringes on a patent for technology that simulates a concert performance via pre-recorded audio and a musical instrument.

Gibson notified Activision of the infringement in a letter on January 7, stating that Activision needed to obtain a license from Gibson .

In response, Activision claimed that Guitar Hero does not violate Gibson's patent, and that the three-year delay between the debut of Guitar Hero and Gibson's allegation has granted the company an implied license.

Interestingly, Gibson previously granted Activision the license to use Gibson instruments in the games and as a model for the series' guitar-shaped controllers.

"Gibson is a good partner, and we have a great deal of respect for them," said Activision general counsel George Rose. "We disagree with the applicability of their patent and would like a legal determination on this."

In related news, media conglomerate Viacom withdrew its Guitar Hero-related lawsuit against Activision yesterday, reports Variety.

Viacom, which purchased Guitar Hero creator Harmonix Music Systems in 2006 while Activision purchased the Guitar Hero brand name itself, had charged Activision with neglecting royalty payments over the technology used in Guitar Hero III: Legends of Rock, which was developed by Activision subsidiary Neversoft.

Viacom alleged that Activision had neglected some $14.5 million in royalty payments. The companies are expected to settle out of court.