Electronic Design
3D TV: Let’s Count The Ways

3D TV: Let’s Count The Ways

If you missed the plethora of 3D HDTV announcements at last month’s International Consumer Electronics Show (CES) in Las Vegas, then you weren’t watching your HDTV. Like it or not, 3D is going to be a big part of presentations, from football games to digital signage with 3D advertising.

There are a number of ways to implement 3D in addition to the real thing or holography. Several techniques can be implemented using flat-screen technology such as LCDs (see the figure).

AUTOSTEREOSCOPIC 3D

Autostereoscopic displays don’t require the viewer to wear any eyewear. The magic is handled at the source using a film that bends the light so each eye views it differently. One way to do this is by implementing a lenticular lens filter film and backlight system (see “3M Film For Viewing 3D Films”).

This approach works best for a single viewer, making it ideal for mobile devices. But companies such as Samsung were demonstrating large LCDs at CES where half a dozen people could view 3D. These displays are primarily designed for digital signage, as quality depends upon the viewer’s position.

ANAGLYPHIC 3D

Anaglyphic 3D uses glasses like the classic red/cyan spectacles that used to be handed out at movie theaters. Images are filtered by color to separate the position of the items being viewed. It works because the brain combines the images from the left and right eye into a single image. A single frame normally combines both images, but it’s possible to alternate images just as other approaches do.

ACTIVE SHUTTER GLASSES

Nvidia’s 3D Vision is an example of an active polarization system designed for gaming. The viewer wears a pair of LCD shutter glasses. Frames for each eye are alternately displayed. An infrared transmitter sends a synchronization signal to the glasses, so one lens is opaque while the other is clear. The brain masks the flickering and merges the images into a 3D image. The viewable frame rate is half the display frame rate.

PASSIVE POLARIZATION

Passive polarization requires a special display covered by a polarized filter where every other line is polarized in a different direction. The polarized glasses allow each eye to see every other line. This cuts the resolution in half, but an HDTV display still looks very good.

Polarized displays are likely to be the mainstay for high-quality HDTV presentations. 3D has been around for quite a while. Samsung DLPs shipped with the feature built in, but there was little 3D content available except for games (see “3D Imaging: You’ve Just Got To See It”). This will change this year as major content providers promise 3D content to match the HDMI 3D standards that now exist.

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