Facebook's Oculus VR is facing a lawsuit alleging that the Rift headset uses a smaller competitor's patented technology.

Techno View IP Inc, a California-based technology licensing firm, sued Facebook and Oculus on Thursday for infringing a 3D imaging patent owned by the VR headset maker ImmersiON-VRelia.

According to the complaint filed in federal court in Delaware, ImmersiON-VRelia agreed to let Techno View litigate the patent on its behalf.

Techno View said Oculus and Facebook infringed a patent held by ImmersiON-VRelia on a method of generating left and right perspectives in a 3D video game.

Last February, a Dallas federal jury found Oculus used copyrighted computer code developed by video game designer John Carmack while employed at ZeniMax.