3D Television Gyaan

What is it?

A television technology which despite creating two dimensional images like any normal television, creates an illusion of realistic three dimensions with or without the use of special glasses.

Who dunnit?

3D television might be the latest buzzword in consumer electronics these days but 3D concept in itself is a technology which dates back to the beginning of photography!!
In 1844, Scottish inventor David Brewster introduced the Stereoscope, a device that could take photographic pictures in 3D.
Stereoscopic 3D television was demonstrated for the first time on August 10th, 1928 by John Logie Baird.
Major television manufacturers began developing 3D home television technology in 2009.

Technology

Basically 3D TV works by separating the left and right images and presenting them in a way that the brain merges them back together and interprets them as a 3D view of a scene. All of them use the same basic principle: they have to produce two separate, moving images and send one of them to the viewer's left eye and the other to the right. To give the proper illusion of 3D, the left eye's image mustn't be seen by the right eye and vice versa.

There are two basic techniques:

i) Using Glasses

This technique can again be designed to project stereoscopic images in three different ways:-

1. Anaglyphic : It involves wearing passive eyeglasses with one red and one cyan colored lenses, also known as anaglyph glasses. The red lens is a light filter that allows only red light to pass through, while the cyan lens allows any light except red. The point is simply that each eye isn't being allowed to see parts of the image that are being viewed by the other one, so each eye gets a slightly different picture of its own. While simple and inexpensive, this technique produces a relatively poor quality, monochrome picture and often makes viewers feel nauseous.

2. Polarizing : It involves wearing passive polarizing eyeglasses which capture two pictures that are projected from the screen using differently polarized light. The left lens receives only light vibrating in vertical plane while the right lens receives light vibrating in horizontal plane. The main drawback is that the TV set has to be fitted with polarizing filters as well, which bumps the cost up quite considerably.

3. Alternate-frame sequencing : The video signal of the TV stores an image meant for the left eye on its even field, and an image meant for the right eye on its odd field. The TV itself is synchronized with the active shutter glasses via infra-red or RF technology. The shutter glasses contain liquid crystal and a polarizing filter which is automatically applied with a slight current that makes it dark, as if a shutter was drawn (hence the name) upon receiving the synced signal. So at a time, only one eye is seeing one image. By viewing these two images from different orientations, a 3D image is built up by the viewer’s brain. Although the user experience is seamless, smooth and rich, due to the rapid drawing of ‘shutters’, lesser light reaches the eye, thus making the image seem darker than it is.

ii) Without using Glasses

The extra need to wear glasses has compelled manufacturers to devise some smart way of avoiding the same. Commercially termed as ‘Auto 3D’, this process allows for autostereoscopic displays. Examples of autostereoscopic displays include parallax barrier, lenticular, volumetric, electro-holographic, and light field displays. Currently most flat-panel solutions employ ‘lenticular lenses’ or ‘parallax barriers’. Let us discuss these two in detail:-

1.  Lenticular lenses : It uses lenticules, which are tiny cylindrical plastic lenses that bend images either to the left or the right.. These are pasted in an array on a transparent sheet, which is then stuck on the display surface of the LCD screen to deliver a magnified image. However, this technology requires a very specific ‘sweet spot’ for getting the 3D effect, and straying even a bit to either side will make the TV’s images seem distorted. Depending on the number of lenticules and the refresh rate of the screen, there can be multiple ‘sweet spots’.

2. Parallax barrier : It is a fine grating of liquid crystal placed in front of the screen, with slits in it that correspond to certain columns of pixels of the TFT screen. These positions are carved so as to transmit alternating images to each eye of the viewer, who is again sitting in an optimal ‘sweet spot’. When a slight voltage is applied to the parallax barrier, its slits direct light from each image slightly differently to the two eyes creating an illusion of depth and thus a 3D image in the brain.

Applications

3D viewing has always fascinated the world in the form of movies, sports and television broadcasts or 3D gaming.
Audiences first got a glimpse of a 3D movie way back in 1922 with the release of "The Power of Love" and off late with the release of “Avatar” it has got an entire new meaning.
Starting on June 11, 2010 ESPN launched a new channel, ‘ESPN 3D’, dedicated to 3D sports with up to 85 live events a year in 3D. The French Open this year was filmed in 3D (center court only) and broadcast live via ADSL and fiber to Orange subscribers throughout France in a dedicated Orange TV channel. Also 25 matches in the FIFA World Cup 2010 were broadcast in 3D.
Nintendo is implementing the Parallax Barrier 3D technology on their latest portable gaming console, the Nintendo 3DS.
Now with a range of 3D enabled television sets hitting the market, the power of 3D technology is sure to enter our homes and our lifestyles. All major manufacturers like Samsung, LG, Toshiba, Sony, and Panasonic are introducing 3D capabilities mostly in higher-end models. Most of them still use the conventional 3D viewing with active shutter glasses as providing 3D images without glasses to many users simultaneously is still a concern (Read the Philips WOWvx story). Sony and Samsung are releasing home-theater setups that can display 3D movies in full high-def glory using a combo of Blu-ray players, TVs and glasses.
Even though 3D viewing has been around for more than century in one form or another it really is still in its infancy and leaves a big hole in the wallet. We can expect more commercial 3D breakthroughs in the coming years as its popularity is on the rise again.