How 3-D TV Works

3-D Ready Televisions

The Mitsubishi Laservue HDTV has the standard 3-D port -- you can use active 3-D glasses with this TV.
The Mitsubishi Laservue HDTV has the standard 3-D port -- you can use active 3-D glasses with this TV.
Courtesy Mitsubishi TV

You can't use a standard television and expect active glasses to work. You must have some way to synchronize the alternating images on the screen with the LCD lenses in the glasses. That's where the stereoscopic sync signal connector comes in. It's a standardized connector with three pins that plugs in to a special port on a 3-D-ready television or monitor. The other end of the cable plugs into an IR emitter. The emitter sends signals to your active 3-D glasses. This is what synchronizes the LCD lenses with the action on the screen.

The connector operates using transistor-transistor logic (TTL). One pin on the connector carries low-voltage electricity. A second pin acts as a ground wire. The third pin carries the stereo sync signal.

There are two different types of 3-D active glasses and they aren't compatible with one another. They are the E-D and ELSA style of 3-D glasses. While emitters for both styles work with the stereoscopic sync signal standard, E-D glasses will only work with an E-D emitter. While a pair of ELSA glasses can synchronize with an E-D emitter, the glasses won't perform properly. For example, when the E-D emitter sends a signal for the left lens to be transparent, the ELSA glasses will make the left lens opaque and cause the right lens to be clear.

Even if you have a 3-D-ready television, an emitter and a pair of active glasses, not everything on your television will appear to be three dimensional. Content providers must optimize the signal for 3-D first. While it's possible to modify existing footage into 3-D content, some providers prefer to create video with 3-D in mind beforehand. Currently, the easiest way to view 3-D content is to connect a computer to your 3-D-ready television using an HDMI cable, and then stream the 3-D content from your computer to your television. In the future, we'll probably see more DVD players capable of sending 3-D signals to televisions and perhaps even incorporate 3-D transmissions into cable and satellite services.