A TV set that renders stereoscopic 3D content using active or passive eyeglass technology. Active 3D TVs use shutter glasses that synchronize with the TV set to open and close each lens at the right time. Passive 3D TVs use less costly polarized glasses that separate the stereo frames by polarization. 3D Sets Hit the Stores in 2010 Active 3D TVs were introduced in the U.S. in the 2010 time frame, and passive polarized LCD-based TVs emerged in 2011. Plasma 3D TVs are all active 3D. For more details, see active 3D, polarized 3D and 3D visualization.