3D eyewear is needed to correctly view the two pictures being shown for the left eye and right eye in today’s commercially available 3D HDTVs. The eyewear filters – or separates – those two images so that just one of them shows up in each eye. When you don’t have the glasses on, the picture is blurry because you are seeing both pictures with both eyes.
The eyewear enables your eyes to see the picture with depth, as your brain processes images the same way it would a scene in ‘real life’. Objects that are closer have more depth as you can see the ‘sides’ of the objects more completely. Objects further from you are more ‘flat’ and have less depth. All 3D eyewear is large enough to ‘wrap around’ almost everyone’s regular glasses.
There are basically two different categories of 3D eyewear – passive eyewear and active shutter eyewear. These correspond to whichever the 3DTV you are watching, and are independent of whether the TV is PDP, LCD, LED or projection. See a comparison of the general active and passive TV characteristics.
Passive eyewear is polarized to accurately work with the two views (left and right) which the TV is showing. There is a film layer on the television itself that displays two pictures polarized to match the polarity of the glasses. Thus, the glasses are not much more complicated than your typical pair of sunglasses.
A passive 3D HDTV has a polarizing film applied to the front glass surface. Currently, these cross-polarized (X-Pol) or micro-polarized monitors are mostly sold for professional and public applications, and are quite costly. Their main advantage is that they work with inexpensive polarized 3D glasses.
Active Shutter Eyewear
Active shutter eyewear is more complicated (and more expensive) because they have a larger role in creating the 3D effect. They have a small battery inside which powers the liquid crystal (LC) shutters that make up each lens. These shutters turn on and off at a very high rate of speed, synced with the left and right eye images displayed by the TV.
Manufacturers are introducing more 3D systems using active glasses for several reasons. The parts for an active shutter system are less expensive and do not add a prohibitive cost to the 3D HDTV itself. Some polarizing films also make the basic TV less bright - a critical factor in high-brightness environments.
Learn about 3D without glasses
Read more about active-shutter eyewear