Understanding 3D TV Technology

Understanding 3D TVs

For those who are less acquainted with home theater offerings in general, we can imagine how perplexing it is to experience the bevy of 3D televisions out there. Whatever happened to the days when TVs were all alike? Why are there different types of glasses accompanying these 3D screens? Can this TV work with other brands' AV equipment? If you find yourself asking similar questions along the way, then this guide is for you. Let us begin by providing you with a little insight on the two major 3D technology before we touch on the various pros and cons of owning a 3D set.  

Stereoscopic televisions stirred up quite a buzz when it first arrived here two years ago. Although the majority of TV makers such as Samsung and Sony still endorse the active-shutter types today, recent alternatives like LG's passive FPR solution has invariably injected greater confusion amongst consumers. (Image source: SlashGear)

The Active 3D Faction

Essentially, a large majority of so-called active 3D televisions utilize the alternate-frame sequencing methodology. In other words, the TV's onscreen images are transmitted to the viewer in alternate sequences. For example, a dedicate frame is designated for the left eye, while the subsequent frame is meant for the right eye. For this to work, active-shutter glasses are required to be worn by the user. These lenses are filled with liquid crystals which turn dark when a voltage is applied. For instance, the left lens is darkened when the right picture frame reaches the right eye, and vice versa for the left eye. These glasses also contain a receiver, which works in tandem with the TV's emitter to coordinate the shuttering lenses with the alternating frames. Each lens shutters on and off at about 50 or 60 times a second, which also explains why an active 3D TV needs to have a minimum of 120Hz (2 x 60Hz) refresh rate. Sony, Samsung and Panasonic are some of the main players in this group.

Along with advancements made in Edge LED technology, contemporary 3D TVs are now slimmer than before. Shown here is Samsung's flagship Series 8 LED Smart TV model which dons a sleek depth of only 29.7mm. And yes, it does 3D as well.   

Active-shutter glasses have been downsized and streamlined over recent times too. Like Samsung's SSG-3700CR, which embodies a lighter and more fashionable profile. Glasses such as these are also rechargeable via USB as well, which makes them more practical than older models depending on flat-cell batteries.

A pictorial representation on the dynamics of active-shutter glasses. A Full-HD frame is transmitted to each eye in alternate sequences at 60 frames per second. This is rapid "shutter" speed possible due to the high-frame rate of modern LCD, LED and plasma televisions. (Image source: www.taor4.com)


Possible replacement for active shutter glasses? Are you game enough to try these? Enjoy!  

The Passive 3D Camp

Unveiled this year, LG's passive Cinema 3D series is undoubtedly the biggest competitor to the active 3D TV troops since its inception. Based on its FPR (Film Patterned Retarder) technology, LG's latest suite of Cinema 3D televisions involve a special circular polarizing film applied unto the panel, designed to transmit simultaneous left and right eye images to the viewer. A pair of polarized lenses then filters the images accordingly. While this process may sound similar to their active-shutter rival, both technologies are actually quite different in the way a 3D picture is transmitted to the viewer.

LG was one of the forerunners in the active-shutter camp when they joined the ranks of Samsung and Sony with their INFINIA series in 2010. This year, the Koreans changed their tune by introducing a line-up of passive 3D screen instead, otherwise known as their Cinema 3D series.

Instead of transmitting one frame for each eye, a single frame is shared between both eyes. In other words, interlaced within each frame are left and right eye fields.This effectively halves the resolution for each eye as well, and also results in a "CRT effect" when viewed up close due to the visible horizontal lines. So how do the Cinema 3D televisions create a stereoscopic effect? To put it simply, each of these left and right eye fields actually consists of segmented odd and even "scans" respectively (see diagram below). The job of the polarized glasses, on the other hand, is to filter these scans such that the left eye only sees the left lines, and vice versa for the right eye. The brain then combines both fields to form a stereoscopic image.

Here's a pictorial representation of LG's Film Pattered Retarder  technology. A new firmware released by LG now revs up the TV's refresh rate from 2 to 4 fields for every 1/200th of a second. Effectively, this enhancement supposedly delivers a full HD 3D frame to each eye at 50Hz. (Image source: flatpanelhd.com)   

Interlaced fields also result in visible horizontal lines or the "CRT effect" when the TV's display is viewed up close. This minor bugbear becomes less evident when the viewing distance is increased.