Active vs. Passive 3D TV

What is the difference between active 3D and passive 3D?

In the world of 3D TV, the two main types of viewing technology are active 3D and passive 3D. Both systems rely on a kind of optical illusion to create a sense of depth within an image, but the means by which this illusion is generated differ. Active 3D requires the accompanying 3D glasses to be electrically charged in order to perceive the depth effect, whereas passive 3D doesn't require powered glasses. The glasses used in passive 3D systems are very similar to the ones you would get if you went to see a 3D movie in the theater.

Beyond 3D TV Glasses: The Differences Between Active and Passive Systems

Active 3D TV systems use a complex technology to generate depth on a two-dimensional plane. Simply put, active 3D glasses work by electronically blocking out your view of the screen in one eye, then the other eye, at a pace so rapid that your brain cannot perceive it. Alternating from the left eye to the right eye, the electronic "shuttering" makes the image you're perceiving appear to be three-dimensional, but it requires that the television has a refresh rate of at least 60 frames per second.

Passive 3D TV systems, on the other hand, have filters in the lenses which polarize the image. These filters also work using left-eye, right-eye principles which allow each eye to see only a certain part of the image. The overall effect gives depth to the picture, and can make certain elements seem to "jump off" the screen.

Passive systems are far more common, as they are less expensive than active systems. Active 3D glasses are heavy and costly, whereas passive 3D glasses are inexpensive and lightweight. However, active 3D systems generate images with superior depth and resolution.

No-Glasses 3D TV?

While 3D TV that does not require glasses is a while away from being ready for the consumer market, it is in development, and it is making strides. The technology behind glasses-free 3D TV is built on the directional emanation of light coming from the TV screen. By directing light at varying angles, the viewer is able to perceive added depth that is not possible with a conventional 2D television. However, you'll have to wait a while for no-glasses 3D TV -- not only is it not yet ready for launch, but it is also expected to be very expensive when it finally does reach the market.

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