You would automatically assume that your TV knows when it is broadcasting a 3D show for it’s stereoscopic viewing pleasure. However, an Italian company, named Sisvel has designed a 3D Switch Device that syncs glasses to the TV.
Totally intrigued, this is how it works. Firstly, It detects if active or passive glasses are being used by the viewer. With active glasses, Sisvel’s device has an capacitive sensor that ‘feels’ the head of the viewer and uses this information to send infrared commands to the TV.
Wearing passive glasses, your TV would have to be equipped with a camera, that looks at the viewers, with it’s special electronics to recognize if they are wearing glasses and can differentiate between ordinary glasses and polarized glasses.