3-D TV Buying Guide

3-D TVs Without Glasses

Those lame glasses that bring your TV's 3-D magic to life aren't so magical; in one survey, about 30 percent of respondents said the glasses were a turn-off for viewers [source: Physorg]. The glasses are unwieldy and breakable, and you might feel downright silly sitting in your living room plastering your face with these spectacles. That's why the idea of glasses-less 3-D TVs is so appealing.

They do exist. They rely on autostereoscopy to produce 3-D images, which is why this technology is sometimes called auto 3-D. There are a couple of technologies in the auto 3-D arena: parallax barrier and lenticular.

In a parallax barrier TV, images are split into alternating vertical columns, and each column is intended for either your right or left eye. Lenses bend the appropriate column toward the correct eye. Your eyes feed all of this visual input to your brain, which helps you perceive what looks like a 3-D picture.

With lenticular technology, tiny plastic lenses (called lenticles) are affixed to a transparent sheet that goes on top of the TV screen. These lenses magnify a portion of the image directly below it, and direct light from the picture at different angles toward your eyes. Each eye picks up a slightly different perspective, and your brain combines the images to complete the 3-D image.

Lenticular and parallax barrier TVs use similar principles to work their magic. They also have the same drawback, which is a very limited sweet spot, the area directly in front of the TV where the 3-D effect is most crisp and pronounced. Manufacturers are working hard to increase the size of the sweet spot so that people will be able to see vivid 3-D images, no matter which angle they're viewing from.

For now, though, auto 3-D TVs are extremely expensive and don't provide the kind of 3-D effects that active shutter and passive TVs create. In a few years, though, this technology may catch up and leave 3-D audiences blissfully glasses-free.