TV technology -- LCD vs. LED vs. 3D made simple

If you are not clued-up on the new TV technologies, it can be overwhelming when trying to understand, and choose from, all the choices out there.  Which is best for what you are looking for in a TV?  LCD, LED or 3D?  If only the answer was so simple!  Unfortunately there are many types of each of the above mentioned categories which means a long-winded comparison with many headings and sub-headings is sure to follow, but is that any more helpful than merely reading the specs (that you hardly understand) of different models you are interested in?  Probably not!  So let us try simplifying the comparison of these technologies for those of us who are not technology gurus and purely want some basic, solid advice in our journey in shopping for our perfect TV.

LCD TVs

LCD TVs are television sets that use Liquid Crystal Display technology to produce images.  This energy efficient technology makes use of liquid-crystal-filled cells that are placed between two sheets of glass and a fluorescent backlight.  The light is shone onto thin film transistors that allow varying amounts of light to pass through the liquid-crystal-filled cells.  The liquid crystals are light-sensitive -- the more light they receive, the darker they become.  Images are then displayed on the screen in monochrome or colour by means of the colour filters that receive the light intensity from the liquid crystals.

Pros:

• Thin, light available in large sizes.
• Energy efficient.
• Largely produced and available.

Cons:

• Lower contrast ratio -- less detail in dark areas of picture.

LED TVs

LED TVs are technically a member of the LCD TV family.  The display screen on a LED is a liquid crystal display the same as it is on any other LCD TV.  The main difference between the two lies within the different backlighting techniques which may change the picture quality characteristics dramatically.

Where LCD TVs use some form of fluorescent lighting, LED TVs use Light Emitting Diodes to light the LCD panel.  Just as there are different styles of fluorescent lights in traditional LCD TVs, there are also different styles of LED backlighting.  In some LED TVs there is a panel of LED lights behind the LCD panel.  These LEDs are tri-coloured and can be controlled in banks for an effect called "local dimming".  This allows darker areas of the picture to have the backlighting dimmed behind them resulting in better contrast and black levels.  Other LED TVs are functionally similar to traditional LCD TVs.  In these TVs, the LED lights are surrounding the edge of the panel, allowing for a very slim depth but without the ability to do local dimming.

Pros:

• Thin, light available in large sizes.
• Higher contrast ratio -- good detail in picture.
• Tri-coloured LEDs make for more realistic colours on screen.
• 'Edge-surrounding' LED TVs use less energy than LCD TVs.

Cons:

• Expensive.
• 'Local-dimming' LED TVs use more energy than LCD TVs.

3D TVs

A 3D TV is a television set that employs techniques of 3D presentation.  To understand how we see a 3D image, we must understand that our eyes are two separate lenses that register two differently-angled images of an object which are sent to the brain, put together and made into one three-dimensional picture in your mind.  Making screens display 3D images is based on a similar mechanism, but is divided into two categories -- Stereoscopic TVs (which require special glasses to see 3D images) and Autostereoscopic TVs (which appear 3D without special accessories).

Stereoscopic TVs require the use of either shutter or polarized glasses.  Both kinds of glasses have the same main use -- they use the lenses to show each eye a different image which are then processed by the brain to form one three-dimensional image in your mind.

Autostereoscopic TVs rely on either lenticular lenses or parallax barrier.  Lenticular lenses are tiny cylindrical plastic lenses that are pasted on a transparent sheet, which is then stuck on the display surface of the LCD screen.  These lenses magnify the images on the screen and when looking at the new cylindrical images, each eye sees different 2D images which are combined by the brain to form one 3D image.  Parallax barrier 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 thin film transistor screen.  These deliberately placed slits direct light from each image slightly differently to each eye, again creating a 3D image in the brain.

Pros:

• High refresh rates make for smooth, rich viewing.
• Autostereoscopic TVs allow the parallax barrier to be turned on/off -- 3D and 2D viewing in one.

Cons:

• Picture seems darker due to less light reaching eyes because of glasses.
• Glasses are inconvenient and take away the simplicity of watching TV.
• Autostereoscopic TVs have a viewing ‘sweet spot’ and the picture will be distorted if the viewer sways from this spot.
• Noted health risks; especially in children, pregnant women and the elderly.

So where does this leave you, the consumer, in your decision in buying a television?  This is just a start to the process.  There are obviously more aspects to consider when comparing TV technologies such as; functional considerations, response time, refresh rate, longevity and cost of specific models you are interested in.  But at least now you can begin on your informed expedition!

We at Digital Allsorts would like to help you on your journey.  Visit our website www.digitalallsorts.co.za and explore the TVs we have in store!  If you need more information or help with understanding our different models, give us call and we will help you in making an informed decision!